1,901 research outputs found

    Disfavored Constitution, Passive Virtues? Linking State Constitutional Fiscal Limitations and Permissive Taxpayer Standing Doctrines

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    This Article contrasts the permissive state taxpayer standing doctrines in place in most states with the restrictive federal and state taxpayer standing rules applied in federal court. It proposes a new theory to explain this disparity, arguing that ubiquitous state constitutional fiscal restrictions, which specifically limit a state government’s ability to tax, spend, and borrow, are a primary impetus in the creation and development of liberal state taxpayer standing doctrines. The Article evaluates this novel hypothesis through an empirical-historical survey of the early state taxpayer standing decisions in every permissive jurisdiction and finds that these provisions are indeed involved in most cases and in most states. It concludes by discussing the implications of these results

    The RMS Survey: Resolving kinematic distance ambiguities towards a sample of compact HII regions using HI absorption

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    We present high-resolution HI data obtained using the Australia Telescope Compact Array to resolve the near/far distance ambiguities towards a sample of compact HII regions from the Red MSX Source (RMS) survey. The high resolution data are complemented with lower resolution archival HI data extracted from the Southern and VLA Galactic Plane surveys. We resolve the distance ambiguity for nearly all of the 105 sources where the continuum was strong enough to allow analysis of the HI absorption line structure. This represents another step in the determination of distances to the total RMS sample, which with over 1,000 massive young stellar objects and compact HII regions, is the largest and most complete sample of its kind. The full sample will allow the distribution of massive star formation in the Galaxy to be examined.Comment: Accepted by MNRAS. This paper consists of 15 pages and contains 10 figures and 5 table

    The RMS Survey: 6 cm continuum VLA observations towards candidate massive YSOs in the northern hemisphere

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    (Abridged) Context: The Red MSX Source (RMS) survey is an ongoing multi-wavelength observational programme designed to return a large, well-selected sample of massive young stellar objects (MYSOs). We have identified \sim2000 MYSO candidates located throughout the Galaxy by comparing the colours of MSX and 2MASS point sources to those of known MYSOs. Aims: To identify the populations of UCHII regions and PNe within the sample and examine their Galactic distribution. Method: We have conducted high resolution radio continuum observations at 6 cm towards 659 MYSO candidates in the northern hemisphere (10\degr< l < 250\degr) using the VLA. In addition to these targeted observations we present archival data towards a further 315 RMS sources extracted from a previous VLA survey of the inner Galaxy. Results: We find radio emission towards 272 (\sim27% of the observed sample). Using results from other parts of our multi-wavelength survey we separate these RMS-radio associations into two distinct types of objects, classifying 51 as PNe and a further 208 as either compact or UC HII regions. Using this well selected sample of HII regions we estimate their Galactic scale height to be 0.6\degr. Conclusions: Using radio continuum and archival data we have identified 79 PNe and 391 HII regions within the northern RMS catalogue. We estimate the total fraction of contamination by PNe in the RMS sample is of order 10%. The sample of HII regions is probably the best representation to date of the Galactic population of HII regions as a whole.Comment: Accepted for publication in Astronomy and Astrophysics. 15 pages, 9 figures and 5 tables. Full versions of Tables 3, 4 and 5 and Figs. 2, 4 and 7 will only be available via CDS or the RMS website at http:/www.ast.leeds.ac.uk/cgi-bin/RMS/RMS_VLA_IMAGES.cg

    Characterisation of the Mopra Radio Telescope at 16--50 GHz

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    We present the results of a programme of scanning and mapping observations of astronomical masers and Jupiter designed to characterise the performance of the Mopra Radio Telescope at frequencies between 16-50 GHz using the 12-mm and 7-mm receivers. We use these observations to determine the telescope beam size, beam shape and overall telescope beam efficiency as a function of frequency. We find that the beam size is well fit by λ\lambda/DD over the frequency range with a correlation coefficient of ~90%. We determine the telescope main beam efficiencies are between ~48-64% for the 12-mm receiver and reasonably flat at ~50% for the 7-mm receiver. Beam maps of strong H2_2O (22 GHz) and SiO masers (43 GHz) provide a means to examine the radial beam pattern of the telescope. At both frequencies the radial beam pattern reveals the presence of three components, a central `core', which is well fit by a Gaussian and constitutes the telescopes main beam, and inner and outer error beams. At both frequencies the inner and outer error beams extend out to approximately 2 and 3.4 times the full-width half maximum of the main beam respectively. Sources with angular sizes a factor of two or more larger than the telescope main beam will couple to the main and error beams, and therefore the power contributed by the error beams needs to be considered. From measurements of the radial beam power pattern we estimate the amount of power contained in the inner and outer error beams is of order one-fifth at 22 GHz rising slightly to one-third at 43 GHz.Comment: Accepted for publication in PAS

    Characterizing fully principal congruence representable distributive lattices

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    Motivated by a recent paper of G. Gr\"atzer, a finite distributive lattice DD is said to be fully principal congruence representable if for every subset QQ of DD containing 00, 11, and the set J(D)J(D) of nonzero join-irreducible elements of DD, there exists a finite lattice LL and an isomorphism from the congruence lattice of LL onto DD such that QQ corresponds to the set of principal congruences of LL under this isomorphism. Based on earlier results of G. Gr\"atzer, H. Lakser, and the present author, we prove that a finite distributive lattice DD is fully principal congruence representable if and only if it is planar and it has at most one join-reducible coatom. Furthermore, even the automorphism group of LL can arbitrarily be stipulated in this case. Also, we generalize a recent result of G. Gr\"atzer on principal congruence representable subsets of a distributive lattice whose top element is join-irreducible by proving that the automorphism group of the lattice we construct can be arbitrary.Comment: 20 pages, 8 figure

    The RMS Survey: Distribution and properties of a sample of massive young stars

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    The Red MSX Source (RMS) survey has identified a large sample of massive young stellar objects (MYSOs) and ultra compact (UC) HII regions from a sample of ~2000 MSX and 2MASS colour selected sources. Using a recent catalogue of molecular clouds derived from the Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey (GRS), and by applying a Galactic scaleheight cut off of 120 pc, we solve the distance ambiguity for RMS sources located within 18\degr 54\degr. These two steps yield kinematic distances to 291 sources out of a possible 326 located within the GRS longitude range. Combining distances and integrated fluxes derived from spectral energy distributions, we estimate luminosities to these sources and find that > 90% are indicative of the presence of a massive star. We find the completeness limit of our sample is ~10^4 Lsun, which corresponds to a zero age main sequence (ZAMS) star with a mass of ~12 Msun. Selecting only these sources, we construct a complete sample of 196 sources. Comparing the properties of the sample of young massive stars with the general population, we find the RMS-clouds are generally larger, more massive, and more turbulent. We examine the distribution of this sub-sample with respect to the location of the spiral arms and the Galactic bar and find them to be spatially correlated. We identify three significant peaks in the source surface density at Galactocentric radii of approximately 4, 6 and 8 kpc, which correspond to the proposed positions of the Scutum, Sagittarius and Perseus spiral arms, respectively. Fitting a scale height to the data we obtain an average value of ~29+-0.5 pc, which agrees well with other reported values in the literature, however, we note a dependence of the scale height on galactocentric radius with it increases from 30 pc to 45 pc between 2.5 and 8.5 kpc.Comment: Accepted for publication by MNRAS. Paper consists of 15 pages including 12 figures and four tables. Full versions of Tables 2 and 3 will only be available online. The resolution of Figure 9 has been reduced - a full resolution version of the paper can be download from here: http://www.ast.leeds.ac.uk/cgi-bin/RMS/RMS_PUBLICATIONS.cg

    The Slope of the Near Infrared Extinction Law

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    We determine the slope of the near infrared extinction power law (Aλλα_{\lambda} \propto \lambda^{-\alpha}) for 8 regions of the Galaxy between l27\sim27^{\circ} and 100\sim100^{\circ}. UKIDSS Galactic Plane Survey data are compared, in colour-colour space, with Galactic population synthesis model data reddened using a series of power laws and convolved through the UKIDSS filter profiles. Monte Carlo simulations allow us to determine the best fit value of α\alpha and evaluate the uncertainty. All values are consistent with each other giving an average extinction power law of α\alpha=2.140.05+0.04^{+0.04}_{-0.05}. This is much steeper than most laws previously derived in the literature from colour excess ratios, which are typically between 1.6 and 1.8. We show that this discrepancy is due to an inappropriate choice of filter wavelength in conversion from colour excess ratios to α\alpha and that effective rather than isophotal wavelengths are more appropriate. In addition, curved reddening tracks, which depend on spectral type and filter system, should be used instead of straight vectors.Comment: Accepted by MNRAS: 11/08/09. 13 pages, 10 figures, 2 table

    Probing discs around massive young stellar objects with CO first overtone emission

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    We present high resolution (R~50,000) spectroastrometry over the CO 1st overtone bandhead of a sample of seven intermediate/massive young stellar objects. These are primarily drawn from the red MSX source (RMS) survey, a systematic search for young massive stars which has returned a large, well selected sample of such objects. The mean luminosity of the sample is approximately 5 times 10^4 L_\odot, indicating the objects typically have a mass of ~15 solar masses. We fit the observed bandhead profiles with a model of a circumstellar disc, and find good agreement between the models and observations for all but one object. We compare the high angular precision (0.2-0.8 mas) spectroastrometric data to the spatial distribution of the emitting material in the best-fitting models. No spatial signatures of discs are detected, which is entirely consistent with the properties of the best-fitting models. Therefore, the observations suggest that the CO bandhead emission of massive young stellar objects originates in small-scale disks, in agreement with previous work. This provides further evidence that massive stars form via disc accretion, as suggested by recent simulations.Comment: Accepted for publication in MNRA

    The implications of sustainable development for airport duty-free business models

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    © HENRY STEWART PUBLICATIONS. This paper considers how the challenges underpinning sustainable development are likely to impact on duty-and tax-free retailing in airports and, by implication, in the entire aviation industry. The paper defines the role of retail as a vital source of airport revenues, before considering the carbon consequences of the sector’s incumbent business models. It finds that products taken onto aircraft increase aircraft weight and fuel burn and are a primary source of carbon emissions for duty-free retailers. The implications for the sector are discussed, and the potential for implementing more sustainable business models is presented. Here it is identified that the specific logistical, economic, and political constraints of operating in the airport make alternative business models difficult, if not impossible to implement. The specialisations that have helped this sector to flourish are constraining their ability to adapt to the climate challenge
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