Optimization of carbon nanotube synthesis from porous anodic Al-Fe-Al templates

A parametric study of carbon nanotube (CNT) synthesis from catalytically active porous anodic Al-Fe-Al multilayer templates was conducted with respect to pore aspect ratio, Fe layer thickness, CNT synthesis temperature, and pre-anodization thermal annealing. Performance metrics included CNT catalytic activity and the pore wall integrity at the Al-Fe-Al interface. The observed CNT density was a strong function of pore diameter, synthesis temperature and pre-anodization annealing of the catalyst film. Vertical pore wall integrity at the Al-Fe-Al interface was optimized by selection of pre-anodization annealing conditions, with interfacial void formation observed in the absence of this technique. Based on CNT growth rates, an activation energy of 0.52 eV was observed for CNT synthesis for all film structures, regardless of pore aspect ratio. The optimization of templated CNT synthesis is expected to assist in the development of high-density vertically oriented CNT-based devices.     

The trithorax group gene moira encodes a brahma-associated putative chromatin-remodeling factor in Drosophila melanogaster

The genes of the trithorax group (trxG) in Drosophila melanogaster are required to maintain the pattern of homeotic gene expression that is established early in embryogenesis by the transient expression of the segmentation genes. The precise role of each of the diverse trxG members and the functional relationships among them are not well understood. Here, we report on the isolation of the trxG gene moira (mor) and its molecular characterization. mor encodes a fruit fly homolog of the human and yeast chromatin-remodeling factors BAF170, BAF155, and SWI3. mor is widely expressed throughout development, and its 170-kDa protein product is present in many embryonic tissues. In vitro, MOR can bind to itself and it interacts with Brahma (BRM), an SWI2-SNF2 homolog, with which it is associated in embryonic nuclear extracts. The leucine zipper motif of MOR is likely to participate in self-oligomerization; the equally conserved SANT domain, for which no function is known, may be required for optimal binding to BRM. MOR thus joins BRM and Snf5-related 1 (SNR1), two known Drosophila SWI-SNF subunits that act as positive regulators of the homeotic genes. These observations provide a molecular explanation for the phenotypic and genetic relationships among several of the trxG genes by suggesting that they encode evolutionarily conserved components of a chromatin-remodeling complex.     

A behaviour instantiation agent architecture

This paper presents a novel agent architecture, the VM-architecture, that chooses its actions via a behaviour instantiation mechanism inspired by Maes?s behaviour networks. The VM-architecture enables an agent, VMattie, built upon it, actively to gather information from humans using email in natural language, to compose announcements of next week?s seminars and to mail them each week to a list that she keeps updated. VMattie does all this without the supervision of a human. Implemented and tested in a UNIX environment, the system?s performance surpassed the authors? fondest hopes.     

The social construction of housing management

Although housing management as an occupational role has existed for over a century it has never received an adequate definition, and its scope and emphasis have varied over time. This paper locates housing management within the debates on the nature of the professions and bureaucracy, and suggests that these analyses are inadequate. It is proposed that a more fruitful approach in understanding the nature of housing management is derived from a consideration of its ‘social construction’. In support of this interpretation material from qualitative empirical research with practitioners is presented and analysed. Key respondents were identified as people working at the boundaries of housing management, such as in a caring or support role, since it was felt that the perceptions of such boundaries were important in defining the limits and limitations of housing management. In conclusion it is suggested that this is a critical moment for housing management in terms of achieving a more rigorous definition of its activities, and of seeking to resolve the conflict between the pressures to organise around commercial objectives and to provide a welfare service. Meanwhile there remains a somewhat paradoxical situation in that whilst the lack of consistent practice within housing management weakens its claims to occupational strength and legitimacy, these same inconsistencies permit individual practitioners the flexibility to offer a more responsive service to those in need.     

On the stability of adaptive pole-placement controllers with asaturating actuator

The authors examine how existing pole-placement algorithms work in the case of a saturating input. The stability of such algorithms and the modifications needed to make them work in the case of saturation are examined. The net result is that the analysis of G.C. Goodwin and K.S. Sin (1984) can be slightly modified to prove the stability of adaptive pole-placement, but only for the case where the plant is stable. It is shown that, for unstable plants, it is possible to push the plant into a state from which it cannot be returned to the origin (with a saturating input). Thus, it is fairly easy to generate examples of instability in the adaptive control system that would not exist with unbounded control authority     

A unified systolic array for adaptive beamforming

We present a new algorithm and systolic array for adaptive beamforming. Our approach improves on McWhirter's pioneering work in two respects. First, our algorithm uses only orthogonal transformations and thus should have better numerical properties. Second, the algorithm can be implemented on one single p × p triangular array of programmable processors that offers a throughput of one residual element per cycle.