4,044 research outputs found

    Cybersecurity Planning for Artificial Intelligent Systems in Space

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    CubeSats continue to proliferate and are an excellent low-cost method of remote sensing. A key piece of intelligent systems is sensory input, data storage, and data communications. With the continued miniaturization of technology, CubeSats will increase their sensory inputs with future miniaturization and enhance their robustness for autonomous operations if data and communications are secure. These futures inspire an intelligent system solution to on-orbit communications. This paper explores a dual-microprocessor approach to improve hardware cybersecurity of intelligent systems, with a view toward intensional intelligence as a means of adjudicating access to sensitive data onboard the CubeSat. With enhanced cybersecurity, Artificial Intelligent Systems (AIS) will add vital utility to otherwise vulnerable, autonomous systems. Using Systems Models-Based Thinking, we shed light on our plan to apply artificial intelligent system concepts to advance CubeSat technology. Managing technology for AIS reduces some of the uncertainties and risks associated with the space environment

    Design, Analysis and Fabrication of Secondary Structural Components for the Habitat Demonstration Unit-Deep Space Habitat

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    In support of NASA s Habitat Demonstration Unit - Deep Space Habitat Prototype, a number of evolved structural sections were designed, fabricated, analyzed and installed in the 5 meter diameter prototype. The hardware consisted of three principal structural sections, and included the development of novel fastener insert concepts. The articles developed consisted of: 1) 1/8th of the primary flooring section, 2) an inner radius floor beam support which interfaced with, and supported (1), 3) two upper hatch section prototypes, and 4) novel insert designs for mechanical fastener attachments. Advanced manufacturing approaches were utilized in the fabrication of the components. The structural components were developed using current commercial aircraft constructions as a baseline (for both the flooring components and their associated mechanical fastener inserts). The structural sections utilized honeycomb sandwich panels. The core section consisted of 1/8th inch cell size Nomex, at 9 lbs/cu ft, and which was 0.66 inches thick. The facesheets had 3 plys each, with a thickness of 0.010 inches per ply, made from woven E-glass with epoxy reinforcement. Analysis activities consisted of both analytical models, as well as initial closed form calculations. Testing was conducted to help verify analysis model inputs, as well as to facilitate correlation between testing and analysis. Test activities consisted of both 4 point bending tests as well as compressive core crush sequences. This paper presents an overview of this activity, and discusses issues encountered during the various phases of the applied research effort, and its relevance to future space based habitats

    Female Mucopolysaccharidosis IIIA Mice Exhibit Hyperactivity and a Reduced Sense of Danger in the Open Field Test

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    Reliable behavioural tests in animal models of neurodegenerative diseases allow us to study the natural history of disease and evaluate the efficacy of novel therapies. Mucopolysaccharidosis IIIA (MPS IIIA or Sanfilippo A), is a severe, neurodegenerative lysosomal storage disorder caused by a deficiency in the heparan sulphate catabolising enzyme, sulfamidase. Undegraded heparan sulphate accumulates, resulting in lysosomal enlargement and cellular dysfunction. Patients suffer a progressive loss of motor and cognitive function with severe behavioural manifestations and premature death. There is currently no treatment. A spontaneously occurring mouse model of the disease has been described, that has approximately 3% of normal enzyme activity levels. Behavioural phenotyping of the MPS IIIA mouse has been previously reported, but the results are conflicting and variable, even after full backcrossing to the C57BL/6 background. Therefore we have independently backcrossed the MPS IIIA model onto the C57BL/6J background and evaluated the behaviour of male and female MPS IIIA mice at 4, 6 and 8 months of age using the open field test, elevated plus maze, inverted screen and horizontal bar crossing at the same circadian time point. Using a 60 minute open field, we have demonstrated that female MPS IIIA mice are hyperactive, have a longer path length, display rapid exploratory behaviour and spend less time immobile than WT mice. Female MPS IIIA mice also display a reduced sense of danger and spend more time in the centre of the open field. There were no significant differences found between male WT and MPS IIIA mice and no differences in neuromuscular strength were seen with either sex. The altered natural history of behaviour that we observe in the MPS IIIA mouse will allow more accurate evaluation of novel therapeutics for MPS IIIA and potentially other neurodegenerative disorders

    Lentiviral Vector Mediated Haematopoietic Stem Cell Gene Therapy For Mucopolysaccharidosis Type IIIA

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    Mucopolysaccharidosis type III (Sanfilippo) is comprised of four phenotypically similar lysosomal storage disorders (MPS IIIA-D) caused by the deficiency of enzymes that catabolise heparan sulphate (HS). Progressive accumulation of HS results in abnormal behaviour, progressive cognitive and motor impairment and death in mid-teens. There are currently no treatments for MPS III. To assess the effect of novel therapeutics in the mouse models of MPS III it is necessary to examine the effect on primary storage of HS, secondary storage and behaviour. The reported behaviour of MPS IIIA and B mice is conflicting therefore we developed a one-hour open field test, performed at the same time of day during a period of hyperactivity observed in a previous circadian rhythm study of MPS IIIB mice. At 8 months of age MPS IIIB mice were hyperactive, with increased rapid exploratory behaviour and a reduction in immobility time. The MPS IIIA mice presented with the same behavioural phenotype as the MPS IIIB mice and were significantly hyperactive at 4 and 6 months of age and also displayed a reduced sense of danger. The hyperactivity and reduced sense of danger observed in the mice is consistent with the patient phenotype. Whilst haematopoietic stem cell transplant (HSCT) is the standard therapy used to treat the similar HS storage disorder MPS I Hurler, it is ineffectual in MPS IIIA. We hypothesise that HSCT failure in MPS IIIA is due to insufficient enzyme production in the brain by donor-derived microglial cells. By increasing expression of N-sulphoglucosamine sulphohydrolase (SGSH) we may be able to treat MPS IIIA. Therefore we compared the effect of HSCT using normal haematopoietic stem cells (WT-HSCT) to lentiviral overexpression of SGSH in normal cells (LV-WT-HSCT) or MPS IIIA cells (LV-IIIA-HSCT) in MPS IIIA mice, using the behavioural tests developed.SGSH activity in the brain of MPS IIIA recipients was not significantly increased by WT-HSCT, but was significantly increased by LV-IIIA-HSCT and LV-WT-HSCT. HS was significantly reduced by all transplants but the best treatment was LV-WT-HSCT. Neuroinflammation, indicated by the number of microglia in the brain, was significantly reduced by all treatments but remains significantly elevated. GM2 gangliosides were significantly reduced by WT-HSCT and LV-WT-HSCT and were no longer significantly elevated, but LV-IIIA-HSCT had no significant effect. Critically LV-WT-HSCT corrected the behaviour at 4 and 6 months of age whilst the other treatments had no significant effect. LV-WT-HSCT and WT-HSCT reduced GM2 gangliosides and neuroinflammation equally but only LV-WT-HSCT corrected behaviour and primary HS storage, suggesting they are the important factors in MPS IIIA pathology.LV-WT-HSCT corrects the neurological phenotype in MPS IIIA mice and is a clinically viable approach to treat MPS IIIA and other neuropathic lysosomal storage disorders

    Stable Mode Sorting by Two-Dimensional Parity of Photonic Transverse Spatial States

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    We describe a mode sorter for two-dimensional parity of transverse spatial states of light based on an out-of-plane Sagnac interferometer. Both Hermite-Gauss (HG) and Laguerre-Gauss (LG) modes can be guided into one of two output ports according to the two-dimensional parity of the mode in question. Our interferometer sorts HG_nm input modes depending upon whether they have even or odd order n+m; it equivalently sorts LG modes depending upon whether they have an even or odd value of their orbital angular momentum. It functions efficiently at the single-photon level, and therefore can be used to sort single-photon states. Due to the inherent phase stability of this type of interferometer as compared to those of the Mach-Zehnder type, it provides a promising tool for the manipulation and filtering of higher order transverse spatial modes for the purposes of quantum information processing. For example, several similar Sagnacs cascaded together may allow, for the first time, a stable measurement of the orbital angular momentum of a true single-photon state. Furthermore, as an alternative to well-known holographic techniques, one can use the Sagnac in conjunction with a multi-mode fiber as a spatial mode filter, which can be used to produce spatial-mode entangled Bell states and heralded single photons in arbitrary first-order (n+m=1) spatial states, covering the entire Poincare sphere of first-order transverse modes.Comment: 11 pages, 12 figures, 2 appendice

    Natural media workshop

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    This workshop will examine what our current imaging and sensing technologies do to our perception. We will examine, using practical examples, the potential to develop more 'Natural Media’ and technologies by broadening the focus of attention to the whole visual, auditory, tactile and sensual field. The aim is to re-incorporate peripheral awareness into our experience using these multiple sense inputs

    The Herschel perspective on nearby galaxies

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    This thesis presents an investigation of local galaxies using new data from the Herschel Space Observatory. Herschel observes the entire far-infrared peak of galaxies, at higher sensitivities and angular resolution than previously possible, and can observe large samples of galaxies or areas of sky. I developed data reduction routines to optimise the data processing of SPIRE extragalactic fields, and found the best methods of flux extraction for galaxies and for fitting of spectral energy distributions. For all the objects I investigated, a single-temperature modified blackbody was a good fit to the global fluxes between 100–500 μm. Within an individual galaxy (i.e., M31, NGC4501 and NGC4567/8) the dust temperature varies between 15–30K. In M31 the dust emissivity index varies between 1.2–2.5 suggesting a change in the physical properties of the grains. The dust and gas are highly correlated in M31, with the gas-to-dust ratio varying from ∼20 in the centre to ∼200 at 18 kpc as expected from the metallicity gradient of the galaxy. By averaging the radial profiles of the late-type objects in the Herschel Reference Survey (HRS), I have shown that dust emission can be traced to at least twice the optical radius (R25) of the galaxy. Within the HRS, dust is detected in 24% of Ellipticals and 62% of S0s and has a mean temperature of 23.9 ± 0.8K for early-type galaxies, warmer than that found for other Herschel studies of late-type galaxies. The mean dust mass for the entire detected early-type sample is logMd = 6.1 ± 0.1M⊙ with a mean dust-to-stellar-mass ratio of log(Md/M∗) = −4.3 ± 0.1, a factor of ∼50 lower dust-to-stellar-mass ratio than for the spiral galaxies in the HRS. The wide range in the dust-to-stellar-mass ratio for ETGs and the lack of a correlation between dust mass and optical luminosity suggest that much of the dust in the ETGs detected by Herschel has been acquired as the result of interactions, although these are unlikely to have had a major effect on the stellar masses of the ETGs

    Information Privacy in a Globally Networked Society: Implications for IS Research

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    This paper presents an extended discussion of issues associated with the role of information privacy in IS research. This discussion was initiated in conjunction with a panel session at ICIS 2002. Following the conference, each of the panelists reworked and extended their position statements, and provided a commentary on the position statements of the other panelists. The paper is framed with head and tail pieces written by the panel chair. The result is a (unique and provocative) blend of opinion and commentary on a topic that is of importance to IS research in the globally networked society in which we all live. IS researchers will find research questions, research conundrums, and research advice in equal measure

    Integrated Photonic Sensing

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    Loss is a critical roadblock to achieving photonic quantum-enhanced technologies. We explore a modular platform for implementing integrated photonics experiments and consider the effects of loss at different stages of these experiments, including state preparation, manipulation and measurement. We frame our discussion mainly in the context of quantum sensing and focus particularly on the use of loss-tolerant Holland-Burnett states for optical phase estimation. In particular, we discuss spontaneous four-wave mixing in standard birefringent fibre as a source of pure, heralded single photons and present methods of optimising such sources. We also outline a route to programmable circuits which allow the control of photonic interactions even in the presence of fabrication imperfections and describe a ratiometric characterisation method for beam splitters which allows the characterisation of complex circuits without the need for full process tomography. Finally, we present a framework for performing state tomography on heralded states using lossy measurement devices. This is motivated by a calculation of the effects of fabrication imperfections on precision measurement using Holland-Burnett states.Comment: 19 pages, 7 figure
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