Topics. Pingos of Tuk     

Tony Waltham 《Geology Today》2003,19(6):212-215

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Gas Flows and Star Formation in the Ringed Galaxy NGC 4736     

Tony Wong  Leo Blitz 《Astrophysics and Space Science》2001,276(2-4):659-666

We present high-resolution (∼5″) BIMA CO observations of the ringed galaxy NGC 4736, along with previously published VLA HI data (Braun, 1995). Strong CO emission is detected from the star-forming ring at r=45″ and in the central region, where a molecular bar is apparent. The azimuthally averaged gas surface density is still much less than the Toomre critical density within r=60″, despite the starburst conditions in the ring (gas depletion time ≲1Gyr). Both CO and HI velocity fields show strong departures from a circular rotating disc model. The velocity residuals are consistent with inflowing gas near the ends of the central bar, outflowing gas between the bar and the ring, and inflowing gas outside the ring. We propose that the high star formation efficiency in the ring results from gas being driven out towards the OLR of the bar and in towards the ILR of the larger oval distortion. However, the strong signature of inflow outside the ring is probably due in part to gas motion in elliptical orbits. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Using Points of Presence to Measure Accessibility to the Commercial Internet   总被引：1，自引：0，他引：1  

Tony H. Grubesic  Morton E. O'Kelly 《The Professional geographer》2002,54(2):259-278

As the Internet continues to grow, questions of accessibility and infrastructure equity persist. In the increasingly competitive telecommunications industry, profit-seeking firms continue to upgrade infrastructure in select market areas creating an uneven spatial distribution of access opportunities. This article utilizes a longitudinal database of Internet infrastructure development, highlighting fiber-optic backbone points of presence (POP) established by commercial Internet service providers to examine city accessibility to the commercial Internet. Results indicate that many larger metropolitan areas maintain dominant shares of telecom infrastructure, but several midsized metros are emerging as important centers for telecommunication interconnection.  相似文献   

Resources— something in reserve?     

Tony Loftas 《Marine Policy》1979,3(1):2

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A fundamental dispute: A discussion of “On some fundamentals of igneous petrology” by Bruce D. Marsh,Contributions to Mineralogy and Petrology (2013) 166: 665–690     

Rais Latypov  Tony Morse  Brian Robins  Richard Wilson  Grant Cawthorn  Christian Tegner  Marian Holness  Charles Lesher  Steve Barnes  Brian O’Driscoll  Ilya Veksler  Michael Higgins  Allan Wilson  Olivier Namur  Sofya Chistyakova  Richard Naslund  Peter Thy 《Contributions to Mineralogy and Petrology》2015,169(2):1-10

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Fisheries: Hope or despair?   总被引：1，自引：0，他引：1  

Tony J. Pitcher  William W.L. Cheung 《Marine pollution bulletin》2013

Recent work suggesting that fisheries depletions have turned the corner is misplaced because analysis was based largely on fisheries from better-managed developed-world fisheries. Some indicators of status show improvements in the minority of fisheries subjected to formal assessment. Other indicators, such as trophic level and catch time series, have been controversial. Nevertheless, several deeper analyses of the status of the majority of world fisheries confirm the previous dismal picture: serious depletions are the norm world-wide, management quality is poor, catch per effort is still declining. The performance of stock assessment itself may stand challenged by random environmental shifts and by the need to accommodate ecosystem-level effects. The global picture for further fisheries species extinctions, the degradation of ecosystem food webs and seafood security is indeed alarming. Moreover, marine ecosystems and their embedded fisheries are challenged in parallel by climate change, acidification, metabolic disruptors and other pollutants. Attempts to remedy the situation need to be urgent, focused, innovative and global.  相似文献   

Environmental recovery in Sydney Harbour,Nova Scotia: Evidence of natural and anthropogenic sediment capping     

Tony R. Walker  Devin MacAskill  Peter Weaver 《Marine pollution bulletin》2013

Contaminants were assessed in Sydney Harbour during baseline and three years of remediation of a former coking and steel facility. Concentrations of PAHs; PCBs; and lead measured in surface sediments indicate overall spatial distribution patterns of historical contaminants remains unchanged, although at much lower concentrations than previously reported due to natural sediment recovery. Recovery rates were in broad agreement with predicted concentrations; or in some cases lower, despite remediation at the Sydney Tar Ponds (STP) site. Contaminants showed little temporal variability, except for detection of significant increases in PAH concentrations during onset of remediation compared to baseline which represented a short term interruption in the overall long term natural recovery of sediments in Sydney Harbour. Recovery (via “capping”) was enhanced following recent harbour dredging activities where less contaminated outer harbour sediments were discharged into a confined disposal facility (CDF) required for a new container in the inner harbour.  相似文献   

Characterization of the atmosphere above a site for millimeter wave astronomy     

Francesco Tony Nasir  Franco Buffa  Gian Luigi Deiana 《Experimental Astronomy》2011,29(3):207-225

The Sardinia Radio Telescope (SRT) is a challeging scientific project managed by the National Institute for Astrophysics (INAF), it is being developed at 30 km North of the city of Cagliari, Italy. The goal of the SRT project is to build a general purpose, fully steerable, 64 m diameter radio telescope, capable of operating with high efficiency in the centimeter and millimeter frequency range (0.3–100 GHz). In portions of this frequency range, especially towards the high end, astronomical observations can be heavily deteriorated by non-optimal atmospheric conditions, especially by water vapor content. The water molecule permanent electric dipole in fact, leads to pressure broadened rotational transitions around the 22.23 GHz spectral line. Furthermore, water vapor’s continuum absorption and emission may influence higher frequency observations too. To a lower degree, cloud liquid black body radiation can also affect centimeter and millimeter observations. In addition to this, inhomogeneities in water vapor distributions can cause signal phase errors which introduce a great amount of uncertainty to VLBI mode observations. The Astronomical Observatory of Cagliari (OA-CA) has obtained historical timeseries of radiosonde profiles conducted at the airport of Cagliari. Through the radiosonde measurements and an appropriate radiative transfer model, we have performed a statistical analysis of the SRT site’s atmosphere which accounts for atmospheric opacity at different frequencies, integrated water vapor (IWV), integrated liquid water (ILW) and cloud cover distributions during the year. This will help to investigate in which period of the year astronomical observations at different frequencies should be performed preferably. The results show that, at the SRT site, K-band astronomical observations are possible all year round, the median opacity at 22.23 GHz is 0.10 Np in the winter (Dec-Jan-Feb) and 0.16 Np in the summer (Jun-Jul-Aug). Integrated water vapor during winter months ranges, on average, between 7 and 15 mm. Cloud cover is usually not present for more than 36% of the time during the year. The atmospheric opacity study indicates that observations at higher frequencies (50–100 GHz) may be performed usefully: the median opacity at 100 GHz is usually below or equal to 0.2 Np in the period that ranges from January to April.  相似文献   

Hard times in Apia? Urban landlessness and the church in Samoa     

Alec Thornton  Tony Binns  Maria Talaitupu Kerslake 《Singapore journal of tropical geography》2013,34(3):357-372

This paper presents findings from a study about the relationships between social change and settlement change in Samoa, where a form of landlessness is emerging in low income areas of the main town, Apia. It examines changing reciprocal kinship arrangements with respect to customary rural village plantation land and changes in both individual and household relationships with the church. Although these relationships are typically closely bound in Pacific island societies, recent field‐based research has revealed the expansion of landless urban settlements with households that are alienated from rural village‐based kin and, by extension, customary land.  相似文献   

Very low-grade metamorphism of Rheno-Hercynian allochthons (Variscides, Germany): facts and tectonic consequences     

Michael Patrick Doublier  Sébastien Potel  Wolfgang Franke  Tony Roache 《International Journal of Earth Sciences》2012,101(5):1229-1252

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