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The Taipan galaxy survey (hereafter simply ‘Taipan’) is a multi-object spectroscopic survey starting in 2017 that will cover 2π steradians over the southern sky (δ ≲ 10°, |b| ≳ 10°), and obtain optical spectra for about two million galaxies out to z < 0.4. Taipan will use the newly refurbished 1.2-m UK Schmidt Telescope at Siding Spring Observatory with the new TAIPAN instrument, which includes an innovative ‘Starbugs’ positioning system capable of rapidly and simultaneously deploying up to 150 spectroscopic fibres (and up to 300 with a proposed upgrade) over the 6° diameter focal plane, and a purpose-built spectrograph operating in the range from 370 to 870 nm with resolving power R ≳ 2000. The main scientific goals of Taipan are (i) to measure the distance scale of the Universe (primarily governed by the local expansion rate, H0) to 1% precision, and the growth rate of structure to 5%; (ii) to make the most extensive map yet constructed of the total mass distribution and motions in the local Universe, using peculiar velocities based on improved Fundamental Plane distances, which will enable sensitive tests of gravitational physics; and (iii) to deliver a legacy sample of low-redshift galaxies as a unique laboratory for studying galaxy evolution as a function of dark matter halo and stellar mass and environment. The final survey, which will be completed within 5 yrs, will consist of a complete magnitude-limited sample (i ⩽ 17) of about 1.2 × 106 galaxies supplemented by an extension to higher redshifts and fainter magnitudes (i ⩽ 18.1) of a luminous red galaxy sample of about 0.8 × 106 galaxies. Observations and data processing will be carried out remotely and in a fully automated way, using a purpose-built automated ‘virtual observer’ software and an automated data reduction pipeline. The Taipan survey is deliberately designed to maximise its legacy value by complementing and enhancing current and planned surveys of the southern sky at wavelengths from the optical to the radio; it will become the primary redshift and optical spectroscopic reference catalogue for the local extragalactic Universe in the southern sky for the coming decade.
We study the fluid–structure interaction (FSI) of a compliant panel with developing Blasius boundary-layer flow. The linearised Navier–Stokes equations in velocity–vorticity form are solved using a Helmholtz decomposition coupled with the dynamics of a plate-spring compliant panel couched in finite-difference form. The FSI system is written as an eigenvalue problem and the various flow- and wall-based instabilities are analysed. It is shown that global temporal instability can occur through the interaction of travelling wave flutter (TWF) with a structural mode or as a resonance between Tollmien–Schlichting wave (TSW) instability and discrete structural modes of the compliant panel. The former is independent of compliant panel length and upstream inflow disturbances while the specific behaviour arising from the latter phenomenon is dependent upon the frequency of a disturbance introduced upstream of the compliant panel. The inclusion of axial displacements in the wall model does not lead to any further global instabilities. The dependence of instability-onset Reynolds numbers with structural stiffness and damping for the global modes is quantified. It is also shown that the TWF-based global instability is stabilised as the boundary layer progresses downstream while the TSW-based global instability exhibits discrete resonance-type behaviour as Reynolds number increases. At sufficiently high Reynolds numbers, a globally unstable divergence instability is identified when the wavelength of its wall-based mode is longer than that of the least stable TSW mode. Finally, a non-modal analysis reveals a high level of transient growth when the flow interacts with a compliant panel which has structural properties capable of reducing TSW growth but which is prone to global instability through wall-based modes.
While early work successfully modelled the stellar population of elliptical galaxies as old, single-age, metal-rich systems, there is evidence that a small amount of recent (i.e. a few Gyrs ago) star formation has occurred in some nearby ellipticals (O'Connell, 1980; Rose, 1985; Pickles, 1985; Bica, 1988). Elliptical galaxies reside in environments ranging from the dense cores of rich clusters to isolated field regions. It has long been suggested that the global properties of ellipticals depend on environment. For example, McClure and Van den Bergh (1968) noted apparent differences in the 380-450nm colours between a set of cluster ellipticals and three from the field. Recent work has tended to support the view that the properties of ellipticals depend on environment (e.g. de Carvalho and Djorgovski, 1992). The most likely cause of these differences is the presence of a small amount of recent star formation in the field ellipticals. This environmental dependency may have important consequences for the use of ellipticals as distance indicators.
Six clusters forming part of the Hydra-Cen Supercluster and its extension on the opposite side of the galactic plane are under study at 21 cm with the Parkes radiotelescope. The infrared Tully-Fisher relation is used to determine the relative distances of the clusters. These clusters exhibit significant and generally positive peculiar velocities ranging from essentially zero for the Hydra cluster to as much as 1000 km/sec for the Pavo and Centaurus clusters. An upper limit of 500 km/sec was previously found in the study of clusters accessible from Arecibo. Data collection is not yet complete, however, and is further subject to unstudied systematic errors due to present reliance on photographic galaxy diameters. Nevertheless, these preliminary results support the notion of a large scale (and presumably gravitationally) disturbed velocity field in the second and third quadrants of the supergalactic plane.
The time-asymptotic linear stability of pulsatile flow in a channel with compliant walls is studied together with the evaluation of modal transient growth within the pulsation period of the basic flow as well as non-modal transient growth. Both one (vertical-displacement) and two (vertical and axial) degrees-of-freedom compliant-wall models are implemented. Two approaches are developed to study the dynamics of the coupled fluid–structure system, the first being a Floquet analysis in which disturbances are decomposed into a product of exponential growth and a sum of harmonics, while the second is a time-stepping technique for the evolution of the fundamental solution (monodromy) matrix. A parametric study of stability in the non-dimensional parameter space, principally defined by Reynolds number (
), Womersley number (
) and amplitude of the applied pressure modulation (
), is then conducted for compliant walls of fixed geometric and material properties. The flow through a rigid channel is shown to be destabilized by pulsation for low
, stabilized due to Stokes-layer effects at intermediate
, while the critical
approaches the steady Poiseuille-flow result at high
, and that these effects are made more pronounced by increasing
. Wall flexibility is shown to be stabilizing throughout the
range but, for the relatively stiff wall used, is more effective at high
. Axial displacements are shown to have negligible effect on the results based upon only vertical deformation of the compliant wall. The effect of structural damping in the compliant-wall dynamics is destabilizing, thereby suggesting that the dominant inflectional (Rayleigh) instability is of the Class A (negative-energy) type. It is shown that very high levels of modal transient growth can occur at low
, and this mechanism could therefore be more important than asymptotic amplification in causing transition to turbulent flow for two-dimensional disturbances. Wall flexibility is shown to ameliorate mildly this phenomenon. As
is increased, modal transient growth becomes progressively less important and the non-modal mechanism can cause similar levels of transient growth. We also show that oblique waves having non-zero transverse wavenumbers are stable to higher values of critical
than their two-dimensional counterparts. Finally, we identify an additional instability branch at high
that corresponds to wall-based travelling-wave flutter. We show that this is stabilized by the inclusion of structural damping, thereby confirming that it is of the Class B (positive-energy) instability type.
The SMAC cluster sample (Hudson et al. 1999), with a depth of ˜ 12000km s-1, has a bulk velocity of ˜ 600 km s-1, with respect to the Cosmic Microwave Background (CMB) frame. Other surveys (Willick 1999, hereafter LP10k; Lauer & Postman 1994, hereafter ACIF) have also yielded large bulk motions on similarly large scales. Taken at face value, these results appear to be in conflict with bulk flows expected from favoured cosmological models. However, at the same time, other surveys (notably Dale et al. 1999, hereafter SC) have found rather small bulk motions on large scales. We have measured bulk flows from the above mentioned surveys plus SNIa (Riess et al. 1995) in a consistent way. The results are given in Table 1. The measurement errors are due to peculiar velocity errors. Note that these are the errors typically quoted. Based on these errors alone, there appears to be conflict between some of the surveys (e.g. SC vs SMAC).
Two classes of elliptical galaxies are now recognised (Kormendy & Bender 1996). Luminous ellipticals rotate slowly (Davies et al. 1983and tend to have boxy isophotes. Ellipticals fainter than L∗ exhibit an increasing tendency to be rotationally supported and to possess a stellar disk component. This dichotomy led Bender, Burstein & Faber (1992) to suggest that the physical variable that controls the ultimate nature of a forming galaxy is the degree of gaseous dissipation that occurs in the final merger it experiences. Low luminosity systems experience more dissipative mergers which generate high rotation, disky end products. As bigger galaxies are formed, the mergers become increasingly stellar, producing the classical slow rotating ellipticals. They termed this the gas/stellar continuum. This global dichotomy is also reflected in the bimodality of core morphologies of the heterogeneous sample of local ellipticals observed with HST. The low luminosity disky galaxies have ‘hard’ cores with a steep slope in the luminosity profile at small radii, whereas the luminous galaxies have ‘soft’ cores with flat profiles at small radii (e.g. Faber et al. 1997).
In the Dublin Journal of 4 April 1769, Thomas Weston, recently arrived from London and ‘versed in the Stucco Art’, announced his proficiency in the ‘Antique Taste’, having worked ‘some Years under the Designs of Mess. Adams, Chambers and Stewart [sic]’. His timing was far from coincidental: less than a month earlier the premium for the design of the Royal Exchange in Dublin, awarded to the English architect Thomas Cooley, had been announced; the competition had generated no less than thirty-three British submissions (or 60% of the total number of competitors). Just as enlightened Irish architectural critics had deemed the employment of an English architect for this particular project as ‘too obvious to be insisted upon’, so it would appear that Weston had identified an opportunity to establish himself in Ireland as an unrivalled exponent of the Neoclassical style. Some weeks later, on 27 April, Weston amended his original advertisement to record that he had ‘served his Apprenticeship to Mr. Rose of London’.
Nutritional requirements for vitamin D during pregnancy have been inadequately described, and there are conflicting data on the impact of gestation on vitamin D status. In the present study, we conducted a longitudinal analysis of total and free (unbound) serum 25-hydroxyvitamin D (25(OH)D), vitamin D-binding protein (DBP) and albumin concentrations in a random sample of thirty women from the Screening for Pregnancy Endpoints Ireland pregnancy cohort study at 15, 20, 24, 28, 32, 36 and 40 weeks of gestation and at 2 months postpartum. Concentrations of serum 25(OH)D, DBP and albumin were determined, and free 25(OH)D was calculated from the concentrations of total 25(OH)D, DBP and albumin. Serum albumin concentration decreased during pregnancy (P< 0·001), with a nadir at 36 weeks (P< 0·005), during which the concentration was approximately 80 % of the postnatal concentration. Serum DBP concentration increased during pregnancy and at 28 weeks of gestation, which was almost double the postnatal level (P< 0·001). Total and free 25(OH)D concentrations decreased (both P< 0·005) as pregnancy progressed, and both were lowest at 36 weeks of gestation. At 15 weeks, 10 and 63 % of the women had serum 25(OH)D concentration < 30 and 50 nmol/l, respectively, which increased to 53 and 80 % at 36 weeks of gestation. The time course of decreasing concentrations of 25(OH)D during gestation among women recruited during May–July, who delivered between October and November, and among those recruited in August–September, who delivered between February and March, was similar. The lower percentage of free 25(OH)D during pregnancy is mainly due to increased DBP.
While recent years have seen rapid growth in the number of galaxy peculiar velocity measurements, disagreements remain about the extent to which the peculiar velocity field - a tracer of the large-scale distribution of mass - agrees with both ΛCDM expectations and with velocity field models derived from redshift surveys. The 6dF Galaxy Survey includes peculiar velocities for nearly 9 000 early-type galaxies (6dFGSv), making it the largest and most homogeneous galaxy peculiar velocity sample to date. We have used the 6dFGS velocity field to determine the amplitude and scale of large-scale cosmic flows in the local universe and test standard cosmological models. We also compare the galaxy density and peculiar velocity fields to establish the distribution of dark and luminous matter and better constrain key cosmological parameters such as the redshift-space distortion parameter.
This article examines hospital provision in Ireland during the early twentieth century. It examines attempts by the newly independent Irish Free State to reform and de-stigmatise medical relief in former workhouse infirmaries. Such reforms were designed to move away from nineteenth century welfare regimes which were underpinned by principles of deterrence. The reform initiated in independent Ireland – the first attempted break-up of the New Poor Law in Great Britain or Ireland – was partly successful. Many of the newly named County and District Hospitals provided solely for medical cases and managed to dissociate such health care provision from the relief of poverty. However, some hospitals continued to act as multifunctional institutions and provided for various categories including the sick, the aged and infirm, ‘unmarried mothers’ and ‘harmless lunatics’. Such institutions often remained associated with the relief of poverty. This article also examines patient fee-payment and outlines how fresh terms of entitlement and means-testing were established. Such developments were even more pronounced in voluntary hospitals where the majority of patients made a financial contribution to their treatment. The article argues that the ability to pay at times determined the type of provision, either voluntary or rate-aided, available to the sick. However, it concludes that the clinical condition of patients often determined whether they entered a more prestigious voluntary hospital or the former workhouse. Although this article concentrates on two Irish case studies, County Kerry and Cork City; it is conceptualised within wider developments with particular reference to the British context.