A radio continuum study of the 'Engraved Hourglass' nebula, MyCn 18     

I. Bains  M. Bryce  M. Calabretta  A. M. Stirling 《Monthly notices of the Royal Astronomical Society》2002,337(2):401-408

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Discovery of a precessing jet nozzle in BL Lacertae     

A. M. Stirling  T. V. Cawthorne  J. A. Stevens  S. G. Jorstad  A. P. Marscher  M. L. Lister  J. L. Gómez  P. S. Smith  I. Agudo  D. C. Gabuzda  E. I. Robson  W. K. Gear 《Monthly notices of the Royal Astronomical Society》2003,341(2):405-422

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Governing epidemics in an age of complexity: Narratives,politics and pathways to sustainability     

Melissa Leach  Ian Scoones  Andrew Stirling 《Global Environmental Change》2010,20(3):369-377

This paper elaborates a ‘pathways approach’ to addressing the governance challenges posed by the dynamics of complex, coupled, multi-scale systems, while incorporating explicit concern for equity, social justice and the wellbeing of poor and marginalised groups. It illustrates the approach in relation to current policy challenges of dealing with epidemics and so-called ‘emerging infectious diseases’ such as avian influenza and haemorrhagic fevers, which involve highly dynamic, cross-scale, often-surprising viral–social–political–ecological interactions. Amidst complexity, we show how different actors in the epidemics field produce particular narratives which frame systems and their dynamics in different ways, promote particular goals and values, and justify particular pathways of disease response. These range from ‘outbreak narratives’ emphasising threat to global populations, to alternative but often marginalised narratives variously emphasising long-term structural, land use and environmental change, local knowledge and livelihood goals. We highlight tendencies – supported by cognitive, institutional and political pressures – for powerful actors and institutions to ‘close down’ around narratives that emphasise stability, underplaying longer term, less controllable dynamics. Arguing that governance approaches need to ‘open up’ to embrace strategies for resilience and robustness in relation to epidemics, we outline what some of the routes towards this might involve, and what the resulting governance models might look like. Key are practices and arrangements that involve flexibility, diversity, adaptation, learning and reflexivity, as well as highlighting and supporting alternative pathways within a progressive politics of sustainability.  相似文献   

The Proximate Composition of the European Bass, Dicentrarchus Labrax (L.) From the Bay of Naples     

Stirling  Hadrian P. 《ICES Journal of Marine Science》1972,34(3):357-364

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Review symposium: our common future: the world commission on environment and development     

David A. M. Lea  Ernst Löffler  Ian Douglas 《The Australian geographer》1989,20(2):195-201

In 1983 the General Assembly of the United Nations called for the setting up of a World Commission on Environment and Development. The Commission's ambitious tasks were described by its Chairman, Gro Harlem Brundtland, Prime Minister of Norway, as: (1) to propose long‐term environmental strategies for achieving sustainable developments by the year 2000 and beyond; (2) to recommend ways concern for the environment could be translated into greater cooperation among developing countries and between countries at different stages of economic and social development; (3) to consider ways and means by which the international community could deal more effectively with environmental concerns; and (4) to help define shared perceptions of long‐term environmental issues and the appropriate efforts needed to deal successfully with problems of protecting and enhancing the environment. The Commission's Report, Our common future,was published in 1987.  相似文献   

Positrons and low energy cosmic rays from supernovae     

Stirling A. Colgate 《Astrophysics and Space Science》1970,8(3):457-462

Burgeret al. (1970) calculated the positron flux from the decay of⁵⁶Co⁵⁶Fe from cosmic rays injected from supernovae. The plasma properties of the ejected matter are determined in the present calculation in order to include the ionization loss of the positrons as the matter expands. It is found that using the matter velocity distribution of previous supernova model calculations that roughly 10% of the positrons escape. The average lifetime in the galaxy due to ionization loss is found to be relatively small, 1.5×10⁵ yr, and with the above injection results in ×3, the observed flux. The same matter velocity distribution is subjected to ionization loss in the galaxy and a steady state low energy, 10E200 MeV, differential flux spectrum is found,J(E)E ^–1.2. This removes the difficulty of the high galactic energy density resulting from a steeper spectrum.  相似文献   

Model for kinetic effects on calcium isotope fractionation (δCa) in inorganic aragonite and cultured planktonic foraminifera     

Nikolaus Gussone  Alexander Heuser  Martin Dietzel  Florian Böhm  David W. Lea  Thomas F. Nägler 《Geochimica et cosmochimica acta》2003,67(7):1375-1382

The calcium isotope ratios (δ⁴⁴Ca = [(⁴⁴Ca/⁴⁰Ca)_sample/(⁴⁴Ca/⁴⁰Ca)_standard −1] · 1000) of Orbulina universa and of inorganically precipitated aragonite are positively correlated to temperature. The slopes of 0.019 and 0.015‰ °C⁻¹, respectively, are a factor of 13 and 16 times smaller than the previously determined fractionation from a second foraminifera, Globigerinoides sacculifer, having a slope of about 0.24‰ °C⁻¹. The observation that δ⁴⁴Ca is positively correlated to temperature is opposite in sign to the oxygen isotopic fractionation (δ¹⁸O) in calcium carbonate (CaCO₃). These observations are explained by a model which considers that Ca²⁺-ions forming ionic bonds are affected by kinetic fractionation only, whereas covalently bound atoms like oxygen are affected by kinetic and equilibrium fractionation. From thermodynamic consideration of kinetic isotope fractionation, it can be shown that the slope of the enrichment factor α(T) is mass-dependent. However, for O. universa and the inorganic precipitates, the calculated mass of about 520 ± 60 and 640 ± 70 amu (atomic mass units) is not compatible with the expected ion mass for ⁴⁰Ca and ⁴⁴Ca. To reconcile this discrepancy, we propose that Ca diffusion and δ⁴⁴Ca isotope fractionation at liquid/solid transitions involves Ca²⁺-aquocomplexes (Ca[H₂O]_n²⁺ · mH₂O) rather than pure Ca²⁺-ion diffusion. From our measurements we calculate that such a hypothesized Ca²⁺-aquocomplex correlates to a hydration number of up to 25 water molecules (490 amu). For O. universa we propose that their biologically mediated Ca isotope fractionation resembles fractionation during inorganic precipitation of CaCO₃ in seawater. To explain the different Ca isotope fractionation in O. universa and in G. sacculifer, we suggest that the latter species actively dehydrates the Ca²⁺-aquocomplex before calcification takes place. The very different temperature response of Ca isotopes in the two species suggests that the use of δ⁴⁴Ca as a temperature proxy will require careful study of species effects.  相似文献   

Analysis of seismic intensities observed in Israel     

Lea Feldman  Avi Shapira 《Natural Hazards》1994,9(3):287-301

Macroseismic data of earthquakes felt in Israel and also recorded instrumentally are analyzed. The analysis yields the following empirical relations:

相似文献    89. Optimum structures of free levelling traverses      Lubomír Kubáček  Lea Bartalošová  Ján Pecár  Reviewer F. Charamza 《Studia Geophysica et Geodaetica》1978,22(1):1-12 Summary Given a configuration of points of a levelling traverse, it is possible to determine their heights according to various plans by applying various optimization criteria. D-, restricted D-and L-optimum plans for various configurations are generally treated. Of two plans belonging to one and the same configuration we consider the one whose determinant, or trace of the covariance matrix of adjusted heights is minimum, to be optimal.Dedicated to RNDr Jan Pícha, CSc., on his 60th Birthday  相似文献    90. Thinning effects on walnut stem and crown diameter growth and fruiting in the walnut-fruit forests of Kyrgyzstan      Jean-Pierre Sorg  Zora Lea Urech  Davlet Mamadzhanov  Maik Rehnus 《山地科学学报》2016,13(9):1558-1566 The walnut-fruit forests (Juglans regia L.) in southern Kyrgyzstan are considered to be biodiversity hotspots and of considerable economic and ecological importance to local populations. The fruiting ability and stability of these forests are, however, decreasing because of infrequent silvicultural interventions and non-existent natural regeneration. Continuous inventories and walnut harvest measurements were carried out on 18 trial and control plots over the course of 13 year. Results showed that i) thinning had a positive influence on diameter at breast height (dbh) increase, ii) dbh growth and crown area increases are strongly and positively correlated, iii) large crowns enhanced the production of fruits, and iv) temperature conditions had a major influence on the production of fruits. The above-mentioned points are particularly relevant for young plantations but are also valid for relatively old plantations (> 50 years). We conclude that regular thinning substantially improves diameter growth, fruit production and ability of trees to withstand wind and snow damage in both young stands and in older walnut-fruit forests.  相似文献    [首页] « 上一页 [3] [4] [5] [6] [7] [8] 9 [10] [11] [12] 下一页 » 末  页»