18,055 research outputs found

    The Value of Design-led Innovation in Chinese SMEs

    Get PDF
    Organised by: Cranfield UniversityThis paper focuses on understanding the role and use of design-led innovation in Chinese SMEs. The insights were gained by undertaking a pilot study, based on an applied developmental research approach involving participatory workshops, quantitative and qualitative positioning activities, in depth case studies and an individual pilot project undertaken with SMEs in the Pearl River Delta [PRD] over an 18 month period. It will discuss the findings, highlighting key areas of uncertainty that SMEs experience when attempting to make the transition from OEM to OBM, and how the findings have contributed to the development of a new design-led innovation framework.Mori Seiki – The Machine Tool Compan

    Strengthening Data Security: an Holistic Approach

    Get PDF
    In the light of heightened concern around data security, this paper highlights some of the measures that can be used to develop and strengthen security in data archiving. The paper includes discussion of the different approaches that can be taken towards the construction of firm and resilient data and information security policies within the social science data archiving communities. While international standards can provide theoretical guidelines for the construction of such a policy, procedures need to be informed by more practical considerations. Attention is drawn to the necessity of following a holistic approach to data security, which includes the education of data creators in the reduction of disclosure risk, the integration of robust and appropriate data processing, handling and management procedures, the value of emerging technological solutions, the training of data users in data security, and the importance of management control, as well as the need to be informed by emerging government security and digital preservation standards

    The impact of spatial fluctuations in the ultra-violet background on intergalactic carbon and silicon

    Get PDF
    Spatial inhomogeneities in the spectral shape of the ultra-violet background (UVB) at the tail-end of HeII reionisation are thought to be the primary cause of the large fluctuations observed in the HeII to HI Ly-a forest optical depth ratio, tau_HeII/tau_HI, at z~2-3. These spectral hardness fluctuations will also influence the ionisation balance of intergalactic metals; we extract realistic quasar absorption spectra from a large hydrodynamical simulation to examine their impact on intergalactic SiIV and CIV absorbers. Using a variety of toy UVB models, we find that while the predicted spatial inhomogeneities in spectral hardness have a significant impact on tau_HeII/tau_HI, the longer mean free path for photons with frequencies above and below the HeII ionisation edge means these fluctuations have less effect on the SiIV and CIV ionisation balance. Furthermore, UVB models which produce the largest fluctuations in specific intensity at the HeII ionisation edge also have the softest ionising spectra, and thus result in photo-ionisation rates which are too low to produce significant fluctuations in the observed tau_SiIV/tau_CIV. Instead, we find spatial variations in the IGM metallicity will dominate any scatter in tau_SiIV/tau_CIV. Our results suggest that observational evidence for homogeneity in the observed tau_SiIV/tau_CIV distribution does not rule out the possibility of significant fluctuations in the UVB spectral shape at z~2-3. On the other hand, the scatter in metallicity inferred from observations of intergalactic CIV and SiIV absorption at z~2-3 using spatially uniform ionisation corrections is likely intrinsic, and therefore provides a valuable constraint on intergalactic metal enrichment scenarios at these redshifts.Comment: 13 pages, 7 figures, accepted to MNRA

    On the rapid demise of Lyman-alpha emitters at z>7 due to the increasing incidence of optically thick absorption systems

    Get PDF
    A variety of independent observational studies have now reported a significant decline in the fraction of Lyman-break galaxies which exhibit Ly-a emission over the redshift interval z=6-7. In combination with the strong damping wing extending redward of Ly-a in the spectrum of the bright z=7.085 quasar ULAS 1120+0641, this has strengthened suggestions that the hydrogen in the intergalactic medium (IGM) is still substantially neutral at z~7. Current theoretical models imply HI fractions as large as 40-90 per cent may be required to explain these data assuming there is no intrinsic evolution in the Ly-a emitter population. We propose that such large neutral fractions are not necessary. Based on a hydrodynamical simulation which reproduces the absorption spectra of high-redshift (z~6-7) quasars, we demonstrate that the opacity of the intervening IGM redward of rest-frame Ly-a can rise rapidly in average regions of the Universe simply because of the increasing incidence of absorption systems which are optically thick to Lyman continuum photons as the tail-end of reionisation is approached. Our simulations suggest these data do not require a large change in the IGM neutral fraction by several tens of per cent from z=6-7, but may instead be indicative of the rapid decrease in the typical mean free path for ionising photons expected during the final stages of reionisation.Comment: 11 pages, 6 figures, accepted to MNRA

    A study of methods to predict and measure the transmission of sound through the walls of light aircraft

    Get PDF
    The objectives are: measurement of dynamic properties of acoustical foams and incorporation of these properties in models governing three-dimensional wave propagation in foams; tests to measure sound transmission paths in the HP137 Jetstream 3; and formulation of a finite element energy model. In addition, the effort to develop a numerical/empirical noise source identification technique was completed. The investigation of a design optimization technique for active noise control was also completed. Monthly progress reports which detail the progress made toward each of the objectives are summarized

    MODULATION OF CALCIUM CHANNELS IN ARTERIAL SMOOTH-MUSCLE CELLS BY DIHYDROPYRIDINE ENANTIOMERS

    Get PDF
    The actions of the optical enantiomers of BAY K 8644 and Sandoz 202,791 were studied on barium inward currents recorded using the whole-cell configuration of the patch clamp technique from enzymatically isolated smooth muscle cells from the rabbit ear artery. The enantiomers were applied by bath perfusion or rapidly by a concentration jump technique, which enabled the study of drug action under equilibrium and nonequilibrium conditions. A larger effect of agonists was seen on peak inward current in 110 mM Ba when small rather than large depolarizations were applied. The midpoint voltage of the steady-state inactivation curve of IBa was -12.8 +/- 1.9 mV (n = 4) in the absence of drug, -16.4 +/- 2.5 mV (n = 4) in 1 microM (+)202,791, and -31.4 +/- 0.4 mV (n = 4) in 1 microM (-)202,791. The rate of onset of action of the agonist and antagonist enantiomers of BAY K 8644 and Sandoz 202,791 was studied by rapid application during 20-ms depolarizing steps from different holding potentials to +30 mV at 1 or 0.2 Hz. The drugs were applied as concentration jumps between two single pulses of a pulse train. The rates of onset of drug action on peak IBa during a 1-Hz pulse train were concentration dependent over the range of 100 nM-3 microM for both (+) and (-)202,791. The rate of onset of inhibition of peak current by antagonist enantiomers was not significantly influenced by the test pulse frequency. At a holding potential of -60 mV, the onset rate of the increase in peak IBa on application of 1 microM of agonist enantiomers (+)202,791 or (-)BAY K 8644 during a train of pulses occurred with mean time constants of 2.1 +/- 0.7 s (n = 7) and 2.3 +/- 0.2 s (n = 4), respectively. The onset of current increase on application of 1 microM (+)202,791 during a single voltage clamp step to 20 mV was faster, with a mean time constant of 380 +/- 80 ms (n = 3)

    Galaxy-Scale Strong Lensing Tests of Gravity and Geometric Cosmology: Constraints and Systematic Limitations

    Full text link
    Galaxy-scale strong gravitational lenses with measured stellar velocity dispersions allow a test of the weak-field metric on kiloparsec scales and a geometric measurement of the cosmological distance-redshift relation, provided that the mass-dynamical structure of the lensing galaxies can be independently constrained to a sufficient degree. We combine data on 53 galaxy-scale strong lenses from the Sloan Lens ACS Survey with a well-motivated fiducial set of lens-galaxy parameters to find (1) a constraint on the post-Newtonian parameter gamma = 1.01 +/- 0.05 and (2) a determination of Omega_Lambda = 0.75 +/- 0.17 under the assumption of a flat universe. These constraints assume that the underlying observations and priors are free of systematic error. We evaluate the sensitivity of these results to systematic uncertainties in (1) total mass-profile shape, (2) velocity anisotropy, (3) light-profile shape, and (4) stellar velocity dispersion. Based on these sensitivities, we conclude that while such strong-lens samples can in principle provide an important tool for testing general relativity and cosmology, they are unlikely to yield precision measurements of gamma and Omega_Lambda unless the properties of the lensing galaxies are independently constrained with substantially greater accuracy than at present.Comment: 8 pages, 5 figures; Accepted to Ap

    The nature and evolution of the highly ionized near-zones in the absorption spectra of z~6 quasars

    Get PDF
    We use state-of-the-art hydrodynamical simulations combined with a 1D radiative transfer code to assess the extent to which the highly ionized regions observed close to z~6 quasars, which we refer to as near-zones, can constrain the ionization state of the surrounding IGM. We find the appearance in Lya absorption of a quasar HII ionization front expanding into a neutral IGM can be very similar to a classical proximity zone, produced by the enhancement in ionizing flux close to a quasar embedded in a highly ionized IGM. The observed sizes of these highly ionized near-zones and their redshift evolution can be reproduced for a wide range of IGM neutral hydrogen fractions for plausible values of the luminosity and lifetime of the quasars. The observed near-zone sizes at the highest observed redshifts are equally consistent with a significantly neutral and a highly ionized surrounding IGM. Stronger constraints on the IGM neutral hydrogen fraction can be obtained by considering the relative size of the near-zones in the Lya and Lyb regions of a quasar spectrum. A large sample of high quality quasar absorption spectra with accurate determinations of near-zone sizes and their redshift evolution in both the Lya and Lyb regions should confirm or exclude the possibility that the Universe is predominantly neutral at the highest observed redshifts. The width of the discrete absorption features in these near-zones will contain important additional information on the ionization state and the previous thermal history of the IGM at these redshifts.Comment: 25 pages, 11 figures, accepted for publication in MNRA
    corecore