A critical-density closed universe in BransDicke theory     

Sergio del Campo  Norman Cruz 《Monthly notices of the Royal Astronomical Society》2000,317(4):825-830

In a BransDicke (BD) cosmological model, the energy density associated with some scalar field decreases as a ^{2[( o +1/2)/( _o +1)]} with the scalefactor a ( t ) of the universe, giving matter with an equation of state In this model, the universe could be closed but still have a non-relativistic matter density corresponding to its critical value, _o =1. Different cosmological expressions, such as luminosity distance, angular diameter, number count and ratio of the redshift thicknessangular size, are determined in terms of the redshift for this model.  相似文献   

10,000 Years of explosive eruptions of Merapi Volcano, Central Java: archaeological and modern implications     

C. G. Newhall  S. Bronto  B. Alloway  N. G. Banks  I. Bahar  M. A. del Marmol  R. D. Hadisantono  R. T. Holcomb  J. McGeehin  J. N. Miksic  M. Rubin  S. D. Sayudi  R. Sukhyar  S. Andreastuti  R. I. Tilling  R. Torley  D. Trimble  A. D. Wirakusumah 《Journal of Volcanology and Geothermal Research》2000,100(1-4)

Stratigraphy and radiocarbon dating of pyroclastic deposits at Merapi Volcano, Central Java, reveals 10,000 years of explosive eruptions. Highlights include:(1) Construction of an Old Merapi stratovolcano to the height of the present cone or slightly higher. Our oldest age for an explosive eruption is 9630±60 ¹⁴C y B.P.; construction of Old Merapi certainly began earlier.(2) Collapse(s) of Old Merapi that left a somma rim high on its eastern slope and sent one or more debris avalanche(s) down its southern and western flanks. Impoundment of Kali Progo to form an early Lake Borobudur at 3400 ¹⁴C y B.P. hints at a possible early collapse of Merapi. The latest somma-forming collapse occurred 1900 ¹⁴C y B.P. The current cone, New Merapi, began to grow soon thereafter.(3) Several large and many small Buddhist and Hindu temples were constructed in Central Java between 732 and 900 A.D. (roughly, 1400–1000 ¹⁴C y B.P.). Explosive Merapi eruptions occurred before, during and after temple construction. Some temples were destroyed and (or) buried soon after their construction, and we suspect that this destruction contributed to an abrupt shift of power and organized society to East Java in 928 A.D. Other temples sites, though, were occupied by “caretakers” for several centuries longer.(4) A partial collapse of New Merapi occurred <1130±50 ¹⁴C y B.P. Eruptions 700–800 ¹⁴C y B.P. (12–14th century A.D.) deposited ash on the floors of (still-occupied?) Candi Sambisari and Candi Kedulan. We speculate but cannot prove that these eruptions were triggered by (the same?) partial collapse of New Merapi, and that the eruptions, in turn, ended “caretaker” occupation at Candi Sambisari and Candi Kedulan. A new or raised Lake Borobudur also existed during part or all of the 12–14th centuries, probably impounded by deposits from Merapi.(5) Relatively benign lava-dome extrusion and dome-collapse pyroclastic flows have dominated activity of the 20th century, but explosive eruptions much larger than any of this century have occurred many times during Merapi's history, most recently during the 19th century.Are the relatively small eruptions of the 20th century a new style of open-vent, less hazardous activity that will persist for the foreseeable future? Or, alternatively, are they merely low-level “background” activity that could be interrupted upon relatively short notice by much larger explosive eruptions? The geologic record suggests the latter, which would place several hundred thousand people at risk. We know of no reliable method to forecast when an explosive eruption will interrupt the present interval of low-level activity. This conclusion has important implications for hazard evaluation.  相似文献   

Granulation structure and information entropy     

F. Berrilli  G. Consolini  A. Florio  D. del Moro  E. Pietropaolo 《Astronomische Nachrichten》2003,324(4):405-405

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On the significance of the climate-dataset time resolution in characterising wind-driven rain and simultaneous wind pressure. Part II: directional analysis     

Pérez-Bella  José M.  Domínguez-Hernández  Javier  Cano-Suñén  Enrique  del Coz-Díaz  Juan J.  Álvarez Rabanal  Felipe P. 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(6):1799-1815

Both semi-empirical methods and CFD simulations use real climate datasets as a basis for determining the building facade exposure to wind-driven rain and simultaneous wind pressure. The time resolution of these datasets and the number of variables considered (commonly rainfall intensity, wind speed and wind direction) determine the required calculation effort and the accuracy of the result. Omitting the wind direction, a former article (Part I of this research) has analysed the effect of this time resolution on two scalar exposure indices obtained by semi-empirical methods: driving rain index (aDRI) and driving-rain wind pressure (DRWP). However, the wind direction during precipitation events also causes significant exposure variations between possible facade orientations. Thus, it is also necessary to clarify the influence of the time resolution of the dataset, on the accuracy of the directional semi-empirical calculation of aDRI and DRWP. To meet this challenge, the article examines 10-min climate records collected between 2001 and 2016 at 6 Spanish locations, uses them to obtain hourly, daily, monthly and annual datasets, and analyses the accuracy of the directional exposure indices associated with each time resolution. The results show that a daily dataset would allow identifying the most exposed orientation with an error less than 45°. However, even the hourly datasets cause errors close to 10% in the exposure values identified on each facade orientation. Finally, adjustment relationships that allow estimating the maximum value of directional exposure from simple scalar indices are obtained.

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Contourite erosive features caused by the Mediterranean Outflow Water in the Gulf of Cadiz: Quaternary tectonic and oceanographic implications     

M. García  F.J. Hernández-Molina  E. Llave  D.A.V. Stow  R. León  M.C. Fernández-Puga  V. Diaz del Río  L. Somoza 《Marine Geology》2009,257(1-4):24-40

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Geopolitical factors of maritime policies and marine spatial planning: State,regions, and geographical planning scope     

Juan L. Suárez de Vivero  Juan C. Rodríguez Mateos  David Florido del Corral 《Marine Policy》2009

This article sets out to explore the extent to which the maritime policies that have been formulated in recent years are public policies on a par with other State-level policies, or whether the geographical domain where they are applied makes them exceptional. Maritime policy and territorial structure are very closely related, and it can be seen that maritime policies are beginning to shift towards the domain of State internal affairs, necessitating the rethinking of the way powers are distributed between territorial bodies that have the legal power to be involved in the formulation of these policies and some instruments, such as marine spatial planning.  相似文献   

Focusing on artisanal fleets in a new scenario: The case of Andalusia (Spain)     

David Florido del Corral   《Marine Policy》2008,32(6):1004-1012

This paper analyses how artisanal fleets in the South Atlantic Coast of Spain (Andalusia) are transformed at the macro-level by political and economic processes. The article will first describe the web of economic and political dynamics, and it will then outline several socioeconomic and cultural patterns of artisanal fleets, examining strategies that are used to encourage commercial specialisation, technological innovation, capitalisation and productive intensification. The resulting social conflict is also examined. From such a study, this essay intends to promote a theoretical debate concerning the importance of new conceptions of artisanal fishing today, a time when local and global processes are highly interconnected.  相似文献   

The paradox of public participation in fisheries governance. The rising number of actors and the devolution process     

Juan L. Suárez de Vivero  Juan C. Rodríguez Mateos  D. Florido del Corral 《Marine Policy》2008

During the process by which the number of actors was increased manifold as a result of the development of civil society, the fisher community has lost prominence and importance, fading into the wide spectrum of interests with which it is competing to make its voice heard in decision-making bodies and in the media. This results in what could be termed the participation paradox—the greater the number of actors, the smaller the role each plays, and the lesser the importance of traditional sectors. Participation and devolution do not bear a linear relationship; greater devolution does not necessarily result in greater participation, a claim that has contributed to the processes of devolution being overvalued. Governance, as interaction between State, civil society and the market, paradoxically might not strengthen the most traditional of the interest groups.  相似文献   

Interpretation of observations by inversion     

J.C. del Toro Iniesta 《Astronomische Nachrichten》2003,324(4):383-387

The most recent developments in inversion techniques of the radiative transfer equation are critically reviewed and some of their findings are summarized to illustrating their achievements. Two significantly different approaches are currently being used that deserve consideration, each characterized by whether or not the model solar atmospheres are changed iteratively by the algorithm. The comparison between the two may help in finding future inversion techniques that can solve many challenging problems of solar physics that still need to be properly settled. These problems themselves suggest strategies that look more suitable than others.  相似文献   

Origin and evolution of the atmospheres of early Venus,Earth and Mars     

Helmut Lammer  Aubrey L. Zerkle  Stefanie Gebauer  Nicola Tosi  Lena Noack  Manuel Scherf  Elke Pilat-Lohinger  Manuel Güdel  John Lee Grenfell  Mareike Godolt  Athanasia Nikolaou 《Astronomy and Astrophysics Review》2018,26(1):2

We review the origin and evolution of the atmospheres of Earth, Venus and Mars from the time when their accreting bodies were released from the protoplanetary disk a few million years after the origin of the Sun. If the accreting planetary cores reached masses \(\ge 0.5 M_\mathrm{Earth}\) before the gas in the disk disappeared, primordial atmospheres consisting mainly of H\(_2\) form around the young planetary body, contrary to late-stage planet formation, where terrestrial planets accrete material after the nebula phase of the disk. The differences between these two scenarios are explored by investigating non-radiogenic atmospheric noble gas isotope anomalies observed on the three terrestrial planets. The role of the young Sun’s more efficient EUV radiation and of the plasma environment into the escape of early atmospheres is also addressed. We discuss the catastrophic outgassing of volatiles and the formation and cooling of steam atmospheres after the solidification of magma oceans and we describe the geochemical evidence for additional delivery of volatile-rich chondritic materials during the main stages of terrestrial planet formation. The evolution scenario of early Earth is then compared with the atmospheric evolution of planets where no active plate tectonics emerged like on Venus and Mars. We look at the diversity between early Earth, Venus and Mars, which is found to be related to their differing geochemical, geodynamical and geophysical conditions, including plate tectonics, crust and mantle oxidation processes and their involvement in degassing processes of secondary \(\hbox {N}_2\) atmospheres. The buildup of atmospheric \(\hbox {N}_2\), \(\hbox {O}_2\), and the role of greenhouse gases such as \(\hbox {CO}_2\) and \(\hbox {CH}_4\) to counter the Faint Young Sun Paradox (FYSP), when the earliest life forms on Earth originated until the Great Oxidation Event \(\approx \) 2.3 Gyr ago, are addressed. This review concludes with a discussion on the implications of understanding Earth’s geophysical and related atmospheric evolution in relation to the discovery of potential habitable terrestrial exoplanets.  相似文献