Probing the physics of interacting galaxies     

Harriet Cullen  Paul Alexander  Marcel Clemens 《Astrophysics and Space Science》2003,284(2):503-506

The morphological and velocity structures in the gaseous (HI and CO) and stellar components of two interacting systems are examined. Both Arp 140 and Arp 104 reveal extended tidal tails in the HI. The Hα and FIR fluxes of Arp 140 yield similar SFR of ∼ 0.8 M_⊙ yr^-1. In contrast the Hα flux of Arp 104 yields a SFR of ∼ 0.05 M_⊙ yr^-1, ∼ 20 times smaller than that obtained from the FIR flux. Spectra were used to examine the changing velocity of atomic and molecular gas in NGC 5218 (Arp 104). The atomic and molecular gas were found to be dynamically similar with comparable velocities and velocity widths across the galaxy; consistent with the two phases responding similarly to the interaction, or enhanced HI to CO conversion in the centre of the galaxy. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Thermodynamic characterization of the partitioning of iron between soluble and colloidal species in the Atlantic Ocean   总被引：2，自引：1，他引：2  

Jay T. Cullen  Bridget A. Bergquist  James W. Moffett 《Marine Chemistry》2006,98(2-4):295-303

Recent electrochemical measurements have shown that iron (Fe) speciation in seawater is dominated by complexation with strong organic ligands throughout the water column and have provided important thermodynamic information about these compounds. Independent work has shown that iron exists in both soluble and colloidal fractions in the Atlantic Ocean. Here we have combined these approaches in samples collected from a variety of regimes within the Atlantic Ocean. We measured the partitioning of Fe between soluble (< 0.02 μm) and colloidal (0.02 to 0.4 μm) size classes and characterized the concentrations and conditional stability constants of Fe ligands within these size classes. Results suggest that equilibrium partitioning of Fe between soluble and colloidal ligands is partially responsible for the distribution of Fe between soluble and colloidal size classes. However, a significant fraction of the colloidal Fe was inert to ligand exchange as soluble Fe concentrations were generally lower than values predicted by a simple equilibrium partitioning model.In surface waters, strong ligands with conditional stability constants of 10¹³ relative to total inorganic Fe appeared to dominate speciation in both the soluble and colloidal fractions. In deep waters these ligands were absent, and instead we found ligands with stability constants 12–15 fold smaller that were predominantly in the soluble pool. Nevertheless, significant levels of colloidal Fe were found in these samples, which we inferred must be inert to coordination exchange.  相似文献   

Impact of the North Atlantic Oscillation on Middle Eastern Climate and Streamflow   总被引：6，自引：0，他引：6  

Heidi M. Cullen  Alexey Kaplan  Phillip A. Arkin  Peter B. deMenocal 《Climatic change》2002,55(3):315-338

Interannual to decadal variations in Middle Eastern temperature, precipitationand streamflow reflect the far-field influence of the North Atlantic Oscillation (NAO), a dominant mode of Atlantic sector climate variability. Using a new sea surface temperature (SST) based index of the NAO and availablestreamflow data from five Middle Eastern rivers, we show that the first principal component of December through March streamflow variability reflects changes in the NAO. However, Middle East rivers have two primary flooding periods.The first is rainfall-driven runoff from December through March, regulated on interannual to decadal timescales by the NAO as reflected in local precipitation and temperature.The second period, from April through June, reflects spring snowmelt and contributes in excess of 50% of annual runoff.This period, known locally as the khamsin, displays no significantNAO connections and a less direct relationship with local climatic factors, suggesting that streamflow variability during this period reflects land-cover change, possibly related to agriculture and hydropower generation, and snowmelt.  相似文献   

Confronting climate change: Critical issues for New Zealand     

Nicolas J. Cullen 《New Zealand geographer》2007,63(3):227-228

  相似文献   

Economic and subsistence values of the standing stocks of seagrass fisheries: Potential benefits of no-fishing marine protected area management     

Richard K.F. Unsworth  Leanne C. Cullen  Jules N. Pretty  David J. Smith  James J. Bell 《Ocean & Coastal Management》2010,53(5-6):218-224

  相似文献   

Galaxy–galaxy weak lensing in the Sloan Digital Sky Survey: intrinsic alignments and shear calibration errors     

Christopher M. Hirata  Rachel Mandelbaum  Uro&#; Seljak  Jacek Guzik  Nikhil Padmanabhan  Cullen Blake  Jonathan Brinkmann  Tamas Budávari  rew Connolly  Istvan Csabai  Ryan Scranton  Alexander S. Szalay 《Monthly notices of the Royal Astronomical Society》2004,353(2):529-549

  相似文献   

Trace element distribution during the reproductive cycle of female and male spiny and Pacific scallops, with implications for biomonitoring   总被引：1，自引：0，他引：1  

Nørum U  Lai VW  Cullen WR 《Marine pollution bulletin》2005,50(2):175-184

Trace element concentrations and contents in gills, gonad, kidneys, mantle, muscle and remainder during the reproductive cycle of female and male spiny and Pacific scallops, from the Strait of Georgia, BC, Canada, were quantified by using ICPMS. The elements investigated were chromium, manganese, iron, cobalt, nickel, selenium, molybdenum, cadmium, tin and mercury. For all ten elements, the tissue distribution was to some extent influenced by species, sex and reproductive status. The implications of the present study in relation to the design of biomonitoring programmes are: (1) care should be taken to ensure an equal/constant sex composition when making interannual comparisons of pooled samples. Preferably the sexes should be monitored separately. (2) the practice of obtaining pooled samples in the interspawn phase is applicable only to monitoring long-term trends in contaminant levels, while the reproductive status should be heeded when studying short-term changes. (3) the present study confirms that direct temporal or spatial comparisons of absolute accumulated element concentrations are only valid intraspecifically.  相似文献   

Partnering between a geography department and a community initiative to provide a wind resource assessment for the Blueskin Bay region,Otago, New Zealand     

Nicolas Cullen  Alice Bowden  Rachel Spronken‐Smith 《New Zealand geographer》2012,68(1):49-61

This paper explores the partnership between a community group and a geography department to assess the wind energy potential of the Blueskin Bay region in southern New Zealand. The partnership has provided opportunities for research and is of strategic importance. Year‐long wind observations and numerical modelling have revealed that the hills surrounding Blueskin Bay show potential for wind energy generation. Despite challenges for both parties, the university–community partnership has allowed a successful research platform to be established.  相似文献   

On the long-term context of the 1997–2009 ‘Big Dry’ in South-Eastern Australia: insights from a 206-year multi-proxy rainfall reconstruction     

Joëlle Gergis  Ailie Jane Eyre Gallant  Karl Braganza  David John Karoly  Kathryn Allen  Louise Cullen  Rosanne D’Arrigo  Ian Goodwin  Pauline Grierson  Shayne McGregor 《Climatic change》2012,111(3-4):923-944

This study presents the first multi-proxy reconstruction of rainfall variability from the mid-latitude region of south-eastern Australia (SEA). A skilful rainfall reconstruction for the 1783–1988 period was possible using twelve annually-resolved palaeoclimate records from the Australasian region. An innovative Monte Carlo calibration and verification technique is introduced to provide the robust uncertainty estimates needed for reliable climate reconstructions. Our ensemble median reconstruction captures 33% of inter-annual and 72% of decadal variations in instrumental SEA rainfall observations. We investigate the stability of regional SEA rainfall with large-scale circulation associated with El Niño–Southern Oscillation (ENSO) and the Inter-decadal Pacific Oscillation (IPO) over the past 206 years. We find evidence for a robust relationship with high SEA rainfall, ENSO and the IPO over the 1840–1988 period. These relationships break down in the late 18th–early 19th century, coinciding with a known period of equatorial Pacific Sea Surface Temperature (SST) cooling during one of the most severe periods of the Little Ice Age. In comparison to a markedly wetter late 18th/early 19th century containing 75% of sustained wet years, 70% of all reconstructed sustained dry years in SEA occur during the 20th century. In the context of the rainfall estimates introduced here, there is a 97.1% probability that the decadal rainfall anomaly recorded during the 1998–2008 ‘Big Dry’ is the worst experienced since the first European settlement of Australia.  相似文献   

Magnitude–frequency relationships of debris flows and debris avalanches in relation to slope relief     

Oldrich Hungr  Scott McDougall  Mike Wise  Michael Cullen 《Geomorphology》2008,96(3-4):355

Probability of occurrence, hazard intensity and encounter probability are key parameters in the quantitative risk analysis (QRA) of landslides. All are strongly dependent on magnitude of the landslides. As a result, magnitude–frequency analysis should be a part of QRA. Deriving representative magnitude–frequency relationships for debris avalanches and debris flows, however, is difficult. One key problem is illustrated with the example of a unique database from the coastal region of British Columbia, Canada, which was compiled entirely from detailed ground investigations. The magnitude of debris avalanches and debris flows is not an independent statistical quantity, but a function of the scale of a given slope, as characterized by the slope length. Thus, attempting to derive probability and magnitude for a given location or sub-region from a regionally-derived magnitude–frequency curve may lead to incorrect predictions. The same problem is pertinent to the application of the same approach to any type of landslide in which the largest combined dimension of the source volume (including entrainment) is of the same order as the length of the slope. It is recommended that greater emphasis be placed on site-specific geological observations, at the expense of generalized statistics.  相似文献