Global perspectives in the geography curriculum: reviewing the moral case for geography – By Alex Standish     

Rachel Tallon 《New Zealand geographer》2012,68(1):73-74

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STAGES: the Space Telescope A901/2 Galaxy Evolution Survey     

Meghan E. Gray  Christian Wolf  Marco Barden  Chien Y. Peng  Boris Häußler  Eric F. Bell  Daniel H. McIntosh  Yicheng Guo  John A. R. Caldwell  David Bacon  Michael Balogh  Fabio D. Barazza  Asmus Böhm  Catherine Heymans  Knud Jahnke  Shardha Jogee  Eelco van Kampen  Kyle Lane  Klaus Meisenheimer  Sebastian F. Sánchez  y Taylor  Lutz Wisotzki  Xianzhong Zheng  David A. Green  R. J. Beswick  D. J. Saikia  Rachel Gilmour  Benjamin D. Johnson  Casey Papovich 《Monthly notices of the Royal Astronomical Society》2009,393(4):1275-1301

We present an overview of the Space Telescope A901/2 Galaxy Evolution Survey (STAGES). STAGES is a multiwavelength project designed to probe physical drivers of galaxy evolution across a wide range of environments and luminosity. A complex multicluster system at   z ∼ 0.165  has been the subject of an 80-orbit F606W Hubble Space Telescope (HST) /Advanced Camera for Surveys (ACS) mosaic covering the full     span of the supercluster. Extensive multiwavelength observations with XMM–Newton , GALEX, Spitzer , 2dF, Giant Metrewave Radio Telescope and the 17-band COMBO-17 photometric redshift survey complement the HST imaging. Our survey goals include simultaneously linking galaxy morphology with other observables such as age, star formation rate, nuclear activity and stellar mass. In addition, with the multiwavelength data set and new high-resolution mass maps from gravitational lensing, we are able to disentangle the large-scale structure of the system. By examining all aspects of an environment we will be able to evaluate the relative importance of the dark matter haloes, the local galaxy density and the hot X-ray gas in driving galaxy transformation. This paper describes the HST imaging, data reduction and creation of a master catalogue. We perform the Sérsic fitting on the HST images and conduct associated simulations to quantify completeness. In addition, we present the COMBO-17 photometric redshift catalogue and estimates of stellar masses and star formation rates for this field. We define galaxy and cluster sample selection criteria, which will be the basis for forthcoming science analyses, and present a compilation of notable objects in the field. Finally, we describe the further multiwavelength observations and announce public access to the data and catalogues.  相似文献   

The correlation of star formation quenching with internal galaxy properties and environment     

Taysun Kimm  Rachel S. Somerville  Sukyoung K. Yi  Frank C. van den Bosch  Samir Salim  Fabio Fontanot  Pierluigi Monaco  Houjun Mo  Anna Pasquali  R. M. Rich  Xiaohu Yang 《Monthly notices of the Royal Astronomical Society》2009,394(3):1131-1147

We investigate the correlation of star formation quenching with internal galaxy properties and large-scale environment (halo mass) in empirical data and theoretical models. We make use of the halo-based group catalogue of Yang and collaborators, which is based on the Sloan Digital Sky Survey. Data from the Galaxy evolution explorer are also used to extract the recent star formation rate. In order to investigate the environmental effects, we examine the properties of 'central' and 'satellite' galaxies separately. For central galaxies, we are unable to conclude whether star formation quenching is primarily connected with halo mass or stellar mass, because these two quantities are themselves strongly correlated. For satellite galaxies, a nearly equally strong dependence on halo mass and stellar mass is seen. We make the same comparison for five different semi-analytic models based on three independently developed codes. We find that the models with active galactic nuclei feedback reproduce reasonably well the dependence of the fraction of central red and passive galaxies on halo mass and stellar mass. However, for satellite galaxies, the same models badly overproduce the fraction of red/passive galaxies and do not reproduce the empirical trends with stellar mass or halo mass. This satellite overquenching problem is caused by the too-rapid stripping of the satellites' hot gas haloes, which leads to rapid strangulation of star formation.  相似文献   

Chitin complex for the remediation of mine impacted water: Geochemistry of metal removal and comparison with other common substrates     

Mary Ann Robinson-Lora  Rachel A. Brennan 《Applied Geochemistry》2010

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The 506 nm absorption feature in pyroxene spectra: Nature and implications for spectroscopy-based studies of pyroxene-bearing targets     

Edward A. Cloutis  Rachel L. Klima 《Icarus》2010,207(1):295-313

High-resolution (0.34 nm) reflectance spectra of a suite of terrestrial ortho- and clinopyroxenes were characterized in the 506-nm region. This region exhibits absorption bands attributed to spin-forbidden transitions in Fe²⁺ located in the M2, and possibly M1, crystallographic site(s). The most intense absorption bands (up to 3.8% deep in <45 μm fractions) are present in low Ca-content orthopyroxene spectra. This region exhibits two (spectral Group I) or more (spectral Group II) absorption bands in the 500-515 nm interval. Group I spectra are associated with the lowest Ca-content samples. For orthopyroxenes, the number of constituent absorption bands and band depths vary as a function of Ca content; increasing Ca content results the appearance of more than two absorption bands and a general reduction in band depths, offsetting an expected increase in band depth with increasing Fe²⁺ content; band depths may also be reduced due to the long wavelength wing of ultraviolet region Fe-O charge transfer absorptions. Band depths and shapes in this region are also a function of grain size, with the strongest bands appearing for larger grain sizes - in the 90-250 μm range. The number and position of constituent absorption bands can be used to constrain factors such as cooling rates, as expressed in the formation of Guinier-Preston zones versus coarser-grained augite exsolution lamellae. Band depths in the spectra of fine-grained (<45 μm) clinopyroxenes do not exceed 1% and are generally lowest for spectral type A clinopyroxenes, where most of the Fe²⁺ is present in the M1 crystallographic site. The appearance of the 506 nm band in the spectra of pyroxene-bearing asteroids can be used to constrain pyroxene composition and structure. The results of this study suggest that detailed analysis of absorption features in the 506 nm region is a powerful tool for determining the composition and structure of pyroxenes. The spectral resolution of the VIR-MS spectrometer aboard the Dawn spacecraft - which will examine Asteroid 4 Vesta, a body possessing surficial pyroxenes - will be sufficient to provide some constraints on pyroxene composition.  相似文献   

The Effects of Reduced Tidal Flushing on Mangrove Structure and Function Across a Disturbance Gradient     

Rachel J. Harris  Eric C. Milbrandt  Edwin M. EverhamIII  Brian D. Bovard 《Estuaries and Coasts》2010,33(5):1176-1185

The effects of reduced tidal flushing on post-hurricane mangrove recovery were measured across a gradient of hurricane disturbance (in order of decreasing wind intensity: Captiva, North Sanibel, Central Sanibel, and East Sanibel). Each region consisted of replicate study plots with either reduced tidal exchange (tidally restricted location) or an open tidal connection (tidally unrestricted location). Locations with reduced tidal exchange displayed significantly lower (two-way ANOVA, p ≤ 0.0001) tidal amplitude, decreased seedling densities, and decreased productivity (recruitment, growth, and litter fall) when compared to the tidally unrestricted locations. Results also indicated significant regional variations in measures of mangrove stand structure (seedlings and canopy) and productivity (recruitment, growth, and litter fall) up to 4-years post-hurricane disturbance. These findings suggest that the legacy effects from hurricane disturbance vary with degree of wind intensity, acting both independently and synergistically with the effects of tidal restriction to influence post-hurricane mangrove structure and function.  相似文献   

Problems with radiocarbon dating the Middle to Upper Palaeolithic transition in Italy     

Thomas Higham  Fiona Brock  Marco Peresani  Alberto Broglio  Rachel Wood  Katerina Douka 《Quaternary Science Reviews》2009,28(13-14):1257-1267

Radiocarbon dating of material from Late Pleistocene archaeological sites is challenging. Small amounts of modern ¹⁴C-labelled contamination will significantly affect the reliability of dates from the period, producing erroneous results. Recent developments in sample pre-treatment chemistry have shown that problems in reliable age determination during this period are surmountable. In this paper we provide an example of one such case, from the Middle to Upper Palaeolithic transitional site of the Grotta di Fumane, in northern Italy. We AMS dated two fractions of the same charcoal samples derived from a series of superimposed Mousterian, Aurignacian and Gravettian levels excavated at the site. One fraction was treated using the routine acid–base–acid (ABA) method, the other with the more rigorous acid–base-oxidation/stepped combustion (ABOx–SC) method. The latter method produced consistently older, and almost certainly more reliable, results. The eruption of the known-age Campanian Ignimbrite from the Phlegrean Fields near present-day Naples at 39.3 ka yr BP seals Ulluzzian and Proto Aurignacian levels in the south of Italy. Equivalent cultural levels are present at Fumane and the results obtained with the ABOx–SC methods are consistent with the ages inferred for sites in the south of Italy based on the presence of the Campanian Ignimbrite. New results from a sample found beneath the Campanian Ignimbrite at the Russian site of Kostenki, obtained using both the ABA and ABOx–SC, methods are also presented. They support the conclusion reached at Fumane by demonstrating that, in many cases, the ABOX–SC treatment effectively removes contamination where the ABA treatment does not. The results of the work offer a sobering examination of the problems inherent in the current radiocarbon database relating to the period, and highlight the dangers of an uncritical use of the corpus of ¹⁴C results obtained over the last few decades. Based on our results, we predict that more than 70% of the 53 previously available determinations from Fumane are erroneously young. A way forward is suggested, using these improved chemical preparation methods, applying analytical methods to characterise the material dated, and testing existing site chronologies to establish which previous determinations are liable to be inaccurate.  相似文献   

Fossils explained 32: Sponges 2     

Rachel Wood 《Geology Today》2000,16(6):236-239

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Infant feeding in North East England: contested spaces of reproduction   总被引：1，自引：0，他引：1  

Rachel Pain  Cathy Bailey  & Graham Mowl 《Area》2001,33(3):261-272

Decisions about infant feeding are commonly viewed as an issue of personal choice made in the light of information about the benefits of breastfeeding. A pilot study of first-time parents' decisions and experiences in Newcastle upon Tyne, England, suggests that local cultural contexts, in particular how men and women are seen to be parenting in different spaces, have a profound influence on infant feeding.  相似文献   

Sulfur isotope systematics at the 21°N site,East Pacific Rise     

John F. Kerridge  Rachel M. Haymon  Miriam Kastner 《Earth and Planetary Science Letters》1983

Hydrogen sulfide in hydrothermal vent fluid at the 21°N site is enriched in ³⁴S relative to Mid-Ocean Ridge basalts, probably by addition of H₂S reduced from seawater sulfate by FeO-bearing basalt. Metalliferous sulfides are depleted in ³⁴S relative to the fluid from which they apparently precipitated, the degree of depletion reflecting the microenvironment in which each mineral crystallised and/or kinetic effects. Isotopic compositions of coexisting sulfides in a basal mound are consistent with equilibration at around 445°C, though heating to such a high temperature seems unlikely. Similar sulfides in a black smoker and in a dead chimney are out of isotopic equilibrium at any temperature, apparently reflecting a complex series of replacement mineralisations and post-depositional oxidation, respectively.  相似文献