3,098 research outputs found

    Revealing the Condensate and Non-Condensate Distributions in the Inhomogeneous Bose-Hubbard Model

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    We calculate the condensate fraction and the condensate and non-condensate spatial and momentum distribution of the Bose-Hubbard model in a trap. From our results, it is evident that using approximate distributions can lead to erroneous experimental estimates of the condensate. Strong interactions cause the condensate to develop pedestal-like structures around the central peak that can be mistaken as non-condensate atoms. Near the transition temperature, the peak itself can include a significant non-condensate component. Using distributions generated from QMC simulations, experiments can map their measurements for higher accuracy in identifying phase transitions and temperature.Comment: 5 pages, 3 figures, 1 tabl

    Cross laminated plywood construction of a free-form roof

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    The paper discusses the design, fabrication and assembly of a free-form roof structure constructed using a hybrid method of cross-laminating structural plywood. The research outlined the roof's design, fabrication and engineering workflow within an integrated fabrication environment led by the architect in collaboration with the engineer. Such workflow constructed resilience in the design and manufacturing process. The digital fabrication of the structure was developed in a single parametric model informed through 3 sets of physical prototypes. By incorporating as-built site information through digital scans, the assembly process was enhanced with feedback to ensure precision in manufacturing, thereby demonstrating care in construction through digital technology

    Optical nanolithography using a scanning near-field probe with an integrated light source

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    An ultracompact near-field optical probe is described that is based on a single, integrated assembly consisting of a gallium nitride (GaN) light-emitting diode (LED), a microlens, and a cantilever assembly containing a hollow pyramidal probe with a subwavelength aperture at its apex. The LED emits ultraviolet light and may be used as a light source for near-field photolithographic exposure. Using this simple device compatible with many commercial atomic force microscope systems, it is possible to form nanostructures in photoresist with a resolution of 35 nm, corresponding to λ/10. © 2008 American Institute of Physics

    Aircraft digital flight control technical review

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    The Aircraft Digital Flight Control Technical Review was initiated by two pilot induced oscillation (PIO) incidents in the spring and summer of 1992. Maj. Gen. Franklin (PEO) wondered why the Air Force development process for digital flight control systems was not preventing PIO problems. Consequently, a technical review team was formed to examine the development process and determine why PIO problems continued to occur. The team was also to identify the 'best practices' used in the various programs. The charter of the team was to focus on the PIO problem, assess the current development process, and document the 'best practices.' The team reviewed all major USAF aircraft programs with digital flight controls, specifically, the F-15E, F-16C/D, F-22, F-111, C-17, and B-2. The team interviewed contractor, System Program Office (SPO), and Combined Test Force (CTF) personnel on these programs. The team also went to NAS Patuxent River to interview USN personnel about the F/A-18 program. The team also reviewed experimental USAF and NASA systems with digital flight control systems: X-29, X-31, F-15 STOL and Maneuver Technology Demonstrator (SMTD), and the Variable In-Flight Stability Test Aircraft (VISTA). The team also discussed the problem with other experts in the field including Ralph Smith and personnel from Calspan. The major conclusions and recommendations from the review are presented

    Suspended tensegrity:the anthropomorphic machine

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    The paper presents a suspended tensegrity "cloud" structure as an interactive art installation with computer vision. Actuated by 12 pneumatic rubber muscles, the research discusses the design, engineering and fabrication challenges of a dynamic tensegrity "cloud". Through material testing and physical prototyping processes, the design workflow enables a cross-disciplinary approach to the problems with feedback and an iterative static analysis approach. The project demonstrates a cross-disciplinary design collaboration between artists, architects, engineers, and the fabricator towards refinement in the engineering of dynamic structures. Using a pneumatic actuation system combined with tensegrity structures, the project demonstrated a method to develop active, controlled, deployable and form-changing envelopes and structures on a larger scale

    Developing a typology of the roles public contributors undertake to establish legitimacy: A longitudinal case study of patient and public involvement in a health network

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    Objective To identify how public contributors established their legitimacy in the functioning of a patient and public involvement programme at a health network. Design A longitudinal case study with three embedded units (projects) involving public contributors. Interviews (n=24), observations (n=27) and documentary data collection occurred over 16 months. Setting The West of England Academic Health Science Network (WEAHSN), 1 of 15 regional AHSNs in England. Participants Interviews were conducted with public contributors (n=5) and professionals (n=19) who were staff from the WEAHSN, its member organisations and its partners. Results Public contributors established their legitimacy by using nine distinct roles: (1) lived experience, as a patient or carer; (2) occupational knowledge, offering job-related expertise; (3) occupational skills, offering aptitude developed through employment; (4) patient advocate, promoting the interests of patients; (5) keeper of the public purse, encouraging wise spending; (6) intuitive public, piloting materials suitable for the general public; (7) fresh-eyed reviewer, critiquing materials; (8) critical friend, critiquing progress and proposing new initiatives and (9) boundary spanner, urging professionals to work across organisations. Individual public contributors occupied many, but not all, of the roles. Conclusions Lived experience is only one of nine distinct public contributor roles. The WEAHSN provided a benign context for the study because in a health network public contributors are one of many parties seeking to establish legitimacy through finding valuable roles. The nine roles can be organised into a typology according to whether the basis for legitimacy lies in: the public contributor's knowledge, skills and experience; citizenship through the aspiration to achieve a broad public good; or being an outsider. The typology shows how public contributors can be involved in work where lived experience appears to lack relevance: strategic decision making; research unconnected to particular conditions; or acute service delivery

    The perceived barriers to the inclusion of rainwater harvesting systems by UK house building companies

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    This work investigates the barriers that exist to deter the implementation of rainwater harvesting into new UK housing. A postal questionnaire was sent to a selection of large, medium and small house-builders distributed across the UK. Questions were asked concerning potential barriers to the inclusion of rainwater harvesting in homes separated into five sections; (1) institutional and regulatory gaps, (2) economic and financial constraints, (3) absence of incentives, (4) lack of information and technical knowledge, and (5) house-builder attitudes. The study concludes that although the knowledge of rainwater systems has increased these barriers are deterring house-builders from installing rainwater harvesting systems in new homes. It is further acknowledged that the implementation of rainwater harvesting will continue to be limited whilst these barriers remain and unless resolved, rainwater harvesting's potential to reduce the consumption of potable water in houses will continue to be limited

    Imaging of compartmentalised intracellular nitric oxide, induced during bacterial phagocytosis, using a metalloprotein–gold nanoparticle conjugate

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    Nitric oxide (NO) plays an essential role within the immune system since it is involved in the break-down of infectious agents such as viruses and bacteria. The ability to measure the presence of NO in the intracellular environment would provide a greater understanding of the pathophysiological mechanism of this important molecule. Here we report the detection of NO from the intracellular phagolysosome using a fluorescently tagged metalloprotein–gold nanoparticle conjugate. The metalloprotein cytochrome c, fluorescently tagged with an Alexa Fluor dye, was self-assembled onto gold nanoparticles to produce a NO specific nanobiosensor. Upon binding of NO, the cytochrome c protein changes conformation which induces an increase of fluorescence intensity of the tagged protein proportional to the NO concentration. The nanobiosensor was sensitive to NO in a reversible and selective manner, and exhibited a linear response at NO concentrations between 1 and 300 μM. In RAW264.7γ NO− macrophage cells, the nanobiosensor was used to detect the presence of NO that had been endogenously generated upon stimulation of the cells with interferon-γ and lipopolysaccharide, or spontaneously released following treatment of the cells with a NO donor. Significantly, the nanobiosensor was shown to be taken up by the macrophages within phagolysosomes, i.e., the precise location where the NO, together with other species, destroys bacterial infection. The nanobiosensor measured, for the first time, increasing concentrations of NO produced during combined stimulation and phagocytosis of Escherichia coli bacteria from within localised intracellular phagolysosomes, a key part of the immune system
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