The rock varnish in the Messak Settafet (Fezzan,Libyan Sahara), age,archaeological context,and paleo-environmental implication     

Mauro Cremaschi 《Geoarchaeology》1996,11(5):393-421

The manganese-rich rock varnish from the Messak Settafet plateau is a relict feature that developed at the end of the Holocene humid cycle, before the onset of the present-day hyperarid conditions. The Messak Settafet varnish consists of three microlayers of different composition and micromorphological features. The innermost microlayer is composed of illuvial clay. The second, middle microlayer is the classic manganese-rich rock varnish. The outermost microlayer is composed of unaltered aeolian dust. Each microlayer formed under different climatic conditions, and the microstratigraphy records a climatic evolution from a wet environment towards progressive desertification. The relationship between desert varnish, rock engravings, and radiocarbon-dated archaeological evidence and the comparison with the Holocene climatic evolution as from cave deposits suggest that most of the varnish developed since the end of the VI millennium B.P. under a semiarid climate characterized by steppe-type vegetation, up to the onset of desert conditions, during the IV millennium B.P. © 1996 John Wiley & Sons, Inc.  相似文献   

Time variant analysis of geomagnetic signals describes the volcanic activity of Mt. Etna between early 2000 and late 2002     

Maurizio Fedi  Lorenzo Cascone  Ciro Del Negro  Mauro La Manna 《Earth and Planetary Science Letters》2008,269(1-2):155-163

Volcanomagnetic anomalies have been mostly observed during strong eruptions. Our aim is to improve the geomagnetic data analysis to evidence the anomalies occurring in a larger time span, especially in the phases preceding the eruptive events. We developed a time variant statistical approach and applied it to the 2000–2002 Etna geomagnetic temporal series. It is based on an algorithm that statistically predicts the geomagnetic field at the station on the volcanic edifice by that recorded at the remote one. In such a way a number of significant changes in the time series (called statistical innovations), marking the local magnetic field change, were detected. The distribution of such statistical innovations accurately describes the Etna volcanic evolution: we note a progressive increase of the innovation occurrence as the eruptive cycles were approaching and only few and weak innovations at times between the various eruptive cycles. The significance of this analysis is further confirmed by the close agreement among the mean square prediction error, strain release and the volcanic activity behavior. On the contrary, the geomagnetic field at a single station or its difference at two stations do not have any clear correlation with other measured physical quantities. The complex pattern of the prediction error was also investigated by a multifractal analysis. We found that the Holder regularity increases with the intensification of the volcanic activity, implying that innovations tend to be less sporadic and correlated during the major volcanic phases.  相似文献   

Implementation and testing of passive control devices based on shape memory alloys     

Mauro Dolce  Donatello Cardone  Roberto Marnetto 《地震工程与结构动力学》2000,29(7):945-968

Two families of passive seismic control devices exploiting the peculiar properties of shape memory alloy (SMA) kernel components have been implemented and tested within the MANSIDE project (Memory Alloys for New Seismic Isolation and Energy Dissipation Devices). They are special braces for framed structures and isolation devices for buildings and bridges. Their most important feature is their extreme versatility, i.e. the possibility to obtain a wide range of cyclic behaviour — from supplemental and fully re‐centring to highly dissipating — by simply varying the number and/or the characteristics of the SMA components. Other remarkable properties are their extraordinary fatigue resistance under large strain cycles and their great durability and reliability in the long run. In this paper, the working mechanisms of the SMA based devices are outlined and the experimental tests carried out to verify the above‐mentioned properties are extensively described. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

A search for the submillimetre counterparts to Lyman break galaxies     

Scott C. Chapman  †  Douglas Scott  Charles C. Steidel  Colin Borys  Mark Halpern  Simon L. Morris  Kurt L. Adelberger  Mark Dickinson  Mauro Giavalisco  Max Pettini 《Monthly notices of the Royal Astronomical Society》2000,319(1):318-330

We have carried out targeted submillimetre observations as part of a programme to explore the connection between the rest-frame ultraviolet and far-infrared properties of star-forming galaxies at high redshift, which is currently poorly understood. On the one hand, the Lyman break technique is very effective at selecting     galaxies. On the other, 'blank-field' imaging in the submillimetre seems to turn up sources routinely, amongst which some are star-forming galaxies at similar redshifts. Already much work has been done searching for optical identifications of objects detected using the SCUBA instrument. Here we have taken the opposite approach, performing submillimetre photometry for a sample of Lyman break galaxies, the ultraviolet properties of which imply high star formation rates. The total signal from our Lyman break sample is undetected in the submillimetre, at an rms level of ∼0.5 mJy, which implies that the population of Lyman break galaxies does not constitute a large part of the recently detected blank-field submillimetre sources. However, our one detection suggests that with reasonable SCUBA integrations we might expect to detect those few Lyman break galaxies that are far-infrared brightest.  相似文献   

Stratigraphic constraints for explosive activity in the past 100 ka at Etna Volcano, Italy     

Mauro Coltelli  Paola Del Carlo  Luigina Vezzoli 《International Journal of Earth Sciences》2000,89(3):665-677

The pyroclastic deposits of Etna have been correlated over the whole volcanic edifice for the first time, allowing the construction of a continuous record of tephra-producing events, which extends from approximately 100 ka to the Present. In this interval, five main periods of explosive activity have been identified: (a) ~100-ka strombolian to subplinian activity; (b) 80- to 100-ka plinian benmoreitic activity; (c) 16- to 80-ka strombolian to subplinian from basaltic to mugearitic activity; (d) 15.5- to 15-ka plinian benmoreitic activity accompanying the caldera-forming eruptions of the Ellittico Volcano; and (e) the most recent 13-ka basaltic explosive activity of strombolian and subplinian type of the present edifice that also includes the 122-B.C. plinian eruption. This study results in a semi-quantitative and in some cases quantitative definition of the intensity and chronology of the explosive activity at Etna. Moreover, this work gives a new significance to the volcanic hazards of Etna, a volcano generally considered to be the site of gentle effusive eruptions.  相似文献   

On the devil's tracks: unexpected news from the Foresta ichnosite (Roccamonfina volcano,central Italy)     

Adolfo Panarello  Maria Rita Palombo  Italo Biddittu  Mauro Antonio Di Vito  Gennaro Farinaro  Paolo Mietto 《第四纪科学杂志》2020,35(3):444-456

The Foresta ichnosite is well known for preserving some of the oldest human fossil footprints recorded in Europe so far. This research aims to: i) describe new footprints that are larger than those already reported, some of which form a new trackway that moves in the opposite direction to all the others; ii) announce the discovery of some stone tools also in the surroundings of the Foresta ichnosite. The new results increase the total number of human fossil footprints to at least 81, specify the direction and the number of footprints of Trackway C, and identify three new directions of walking at the site. More compelling and complete estimates of the dimensional range of all ichnological evidence enables us, furthermore, to estimate the number of trackmakers walking on the trampled surface as a minimum of five, one of them likely being an adult male. The general shape of all the recorded footprints suggests that the Foresta trackmakers share some similarities with those at Sima de los Huesos, and belong to the same taxonomical group as the Ceprano skull. All the new evidence enables us to better understand the presence of hominin populations in the Roccamonfina volcano area during the Middle Pleistocene. © 2020 John Wiley & Sons, Ltd.  相似文献   

Predicting new snow density in the Italian Alps: A variability analysis based on 10 years of measurements          下载免费PDF全文

Mauro Valt  Nicolas Guyennon  Franco Salerno  Anna B. Petrangeli  Rosamaria Salvatori  Paola Cianfarra  Emanuele Romano 《水文研究》2018,32(20):3174-3187

Despite its strong impact on the time evolution of the snowpack, current estimation of new snow density (ρ_hn) is usually accomplished either by using local empirical techniques or by assuming a constant snow density. Faced with the lack of an estimation model of ρ_hn valid for a wide spatial scale and supported by a suitable number of observations, this study aims to develop simple monthly linear regression models at scale of the entire Italian Alpine chain based on 12,112 snowfall observations at 122 stations, using only air temperature as predictor. Moreover, the remaining variance is investigated in both time and space, also considering some qualitative features of the snowfall events. The daily ρ_hn measurements present a mean value of 115 kg m^?3 (105 and 159 kg m^?3 for dry and wet conditions, respectively). The mean air temperature of the 24 hr preceding the snowfall event has been found to be the best predictor of the ρ_hn, within 31% of uncertainty. The analysis of associated residues allows supporting the idea that the adoption of a more local approach than the one analysed here is not able to substantially increase the predictive capabilities of the model. In fact, the main factor explaining the remaining variance over the air temperature is the wind, but in a complex orography, as mountain regions are, supplying realistic local wind fields is particularly challenging. Therefore, we conclude that using only the daily mean temperature as predictor is a good choice for estimating daily new snow density at scale of Italian Alpine chain, as well as at more regional scale.  相似文献   

Deciphering post-caldera volcanism: insight into the Vulcanello (Island of Vulcano,Southern Italy) eruptive activity based on geological and petrological constraints   总被引：1，自引：1，他引：0  

Raffaella Fusillo  Federico Di Traglia  Anna Gioncada  Marco Pistolesi  Paul J. Wallace  Mauro Rosi 《Bulletin of Volcanology》2015,77(9):1-23

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Soil erosion processes in subtropical plantations (Diospyros kaki) managed under flood irrigation in Eastern Spain     

Jesús Rodrigo-Comino  Mauro Ponsoda-Carreres  David Salesa  Enric Terol  Yeboah Gyasi-Agyei  Artemi Cerdà 《Singapore journal of tropical geography》2020,41(1):120-135

Persimmons (Diospyros kaki) are trees cultivated under subtropical environmental conditions but are also found in other regions such as the Mediterranean. However, no research has been conducted to investigate soil erosion processes under Mediterranean soil management systems characterized by flood irrigation and/or tillage. The Improved Stock Unearthing Method (ISUM) for assessing long-term soil mobilization was applied to two fields, one under tillage and the other under no-till with herbicide within a 25-year old Mediterranean persimmon plantation. Replicating methods used in vineyard studies, graft unións on persimmon plants were used as passive bio-indicators of soil surface changes in this study. The tilled field showed a total soil mobilization volume of 48.4 m³ on a 408.5 m² plot, representing a total soil loss of 52.6 Mg ha^-1 yr^-1. For the plot (468 m²) managed with no-till and herbicide, the results indicated total soil mobilization of 33.6 m³ which translates to 31.9 Mg ha^-1 yr^-1. It is concluded that flood irrigation is able to modify the runoff pathways and landforms in Mediterranean persimmon plantations, and the flood impact is more extensive when combined with tillage. For the first time, ISUM has been successfully applied to estimate soil erosion in a plantation under flood irrigation.  相似文献   

Preface to special issue on numerical modelling of URM buildings: benchmark project     

Dolce  Mauro  Lagomarsino  Sergio  Varum  Humberto 《Bulletin of Earthquake Engineering》2022,20(4):1897-1900

Bulletin of Earthquake Engineering -  相似文献