The emplacement of Variscan HT metamorphic rocks linked to the interaction between Gondwana and Laurussia: structural constraints in NE Sardinia (Italy)     

Franco Marco Elter  Matteo Padovano  Rita Katharina Kraus 《地学学报》2010,22(5):369-377

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Cycles of humid‐dry climate conditions around the P/E boundary: new stable isotope data from terrestrial organic matter in Vasterival section (NW France)     

Jean‐Yves Storme  Christian Dupuis  Johann Schnyder  Florence Quesnel  Sylvain Garel  Alina I. Iakovleva  Paola Iacumin  Antonietta Di Matteo  Mathieu Sebilo  Johan Yans 《地学学报》2012,24(2):114-122

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Co-evolution of coarse grain structuring and bed roughness in response to episodic sediment supply in an experimental aggrading channel     

Marwan A. Hassan  Matteo Saletti  Chendi Zhang  Carles Ferrer-Boix  Joel P.L. Johnson  Tobias Müller  Claudia von Flotow 《地球表面变化过程与地形》2020,45(4):948-961

We use flume experiments to better understand how gravel-bed channels maintain bed surface stability in response to pulses of sediment supply. Bed elevations and surface imagery at high spatial resolutions were used to quantify the co-evolution of surface grain-size distribution (GSD), bed roughness statistics, and bed surface structures (clusters, cells and transverse features). Using a new semi-automated method, we identified individual stone structures over a 2 m × 1 m area throughout the experiments. After an initial coarsening, surface GSD and armouring ratio remained nearly stable as sediment pulses caused net bed aggradation. In contrast, individual grain structures continued to form, increase or decrease in size, and disappear throughout the experiments. The response of the bed to sediment pulses depended on the history of surface roughness evolution and bed surface structure development, as these factors changed much more in response to supply perturbations earlier in the experiments compared to later, even as the bed continued to aggrade. We interpret that the dynamic production and destruction of bed surface structures can act as a ‘buffer’ to sediment supply pulses, maintaining a stable bed surface during aggradation with minimal change in grain size or armouring. © 2019 John Wiley & Sons, Ltd.  相似文献   

Width variations control the development of grain structuring in steep step-pool dominated streams: insight from flume experiments     

Matteo Saletti  Marwan A. Hassan 《地球表面变化过程与地形》2020,45(6):1430-1440

We report results from flume experiments designed to study the effect of width variations on the formation and stability of steps in steep streams. To physically model channel width changes we inserted multiple trapezoidal elements in the flume. Two competing effects are in play: a fluidic effect, suggesting that steps are more likely to form in wide areas because of deposition enhanced by lower shear stress, and a granular effect, suggesting that steps are more likely to form in narrow areas because of particle jamming. Our experiments show that width variations enhance the formation of steps. Although steps can form in every location, those in narrow/narrowing areas are more common, more stable and they occupy a larger portion of the channel width. These results stress the importance of particle interactions in coarse-bedded streams and help river engineers by providing a new element to consider when designing step-pool sequences in river restoration projects. © 2020 John Wiley & Sons, Ltd.  相似文献   

Strong observational constraints on advection-dominated accretion in the cores of elliptical galaxies     

T. Di Matteo †  A. C. Fabian  M. J. Rees  C. L. Carilli  R. J. Ivison 《Monthly notices of the Royal Astronomical Society》1999,305(3):492-504

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Multilevel models for analyzing people’s daily movement behavior   总被引：1，自引：0，他引：1  

Matteo Bottai  Nicola Salvati  Nicola Orsini 《Journal of Geographical Systems》2006,8(1):97-108

A survey on the daily movement behavior of the people residing in the territory of the Municipality of Pisa, Italy, was carried out in October 2002. This work is aimed at modeling the distance covered and the number of trips taken in a day as functions of several individual characteristics. In order to take the potential intra-family and intra-area correlation of the observations into account, multilevel models are estimated. We use two and three level hierarchical linear and Poisson models to estimate the number of daily trips taken by an individual. Likelihood ratio tests indicate the movement behavior in 1 day is more alike for individuals within a family than for individuals from different families.  相似文献   

Size,shape and spatial arrangement of mega‐scale glacial lineations from a large and diverse dataset          下载免费PDF全文

Matteo Spagnolo  Chris D. Clark  Jeremy C. Ely  Chris R. Stokes  John B. Anderson  Karin Andreassen  Alastair G. C. Graham  Edward C. King 《地球表面变化过程与地形》2014,39(11):1432-1448

Mega‐scale glacial lineations (MSGLs) are a characteristic landform on ice stream beds. Solving the puzzle of their formation is key to understanding how ice interacts with its bed and how this, in turn, influences the dynamics of ice streams. However, a comprehensive and detailed characterization of this landform's size, shape and spatial arrangement, which might serve to test and refine formational theories, is largely lacking. This paper presents a detailed morphometric analysis and comparison of 4043 MSGLs from eight palaeo‐ice stream settings: three offshore (Norway and Antarctica), four onshore (Canada), and one from under a modern ice stream in West Antarctica. The length of MSGLs is lower than previously suggested (mode 1000–2000 m; median 2892 m), and they initiate and terminate at various locations on an ice stream bed. Their spatial arrangement reveals a pattern that is characterized by an exceptional parallel conformity (80% of all mapped MSGLs have an azimuth within 5° from the mean values), and a fairly constant lateral spacing (mode 200–300 m; median 330 m), which we interpret as an indication that MSGLs are a spatially self‐organized phenomenon. Results show that size, shape and spatial arrangement of MSGLs are consistent both within and also generally between different ice stream beds. We suggest this results from a common mechanism of formation, which is largely insensitive to local factors. Although the elongation of MSGLs (mode 6–8; median 12.2) is typically higher than features described as drumlins, these values and those of their width (mode 100–200 m; median 268 m) overlap, which suggests the two landforms are part of a morphological continuum and may share a similar origin. We compare their morphometry with explicit predictions made by the groove‐ploughing and rilling instability theories of MSGL formation. Although the latter was most compatible, neither is fully supported by observations. © 2014 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd.  相似文献   

On the importance of high-redshift intergalactic voids     

Matteo Viel  Jörg M. Colberg  T.-S. Kim 《Monthly notices of the Royal Astronomical Society》2008,386(3):1285-1293

We investigate the properties of 1D flux 'voids' (connected regions in the flux distribution above the mean-flux level) by comparing hydrodynamical simulations of large cosmological volumes with a set of observed high-resolution spectra at z ∼ 2. After addressing the effects of box size and resolution, we study how the void distribution changes when the most significant cosmological and astrophysical parameters are varied. We find that the void distribution in the flux is in excellent agreement with predictions of the standard Λcold dark matter (ΛCDM) cosmology, which also fits other flux statistics remarkably well. We then model the relation between flux voids and the corresponding 1D gas-density field along the line of sight and make a preliminary attempt to connect the 1D properties of the gas-density field to the 3D dark matter distribution at the same redshift. This provides a framework that allows statistical interpretations of the void population at high redshift using observed quasar spectra, and eventually it will enable linking the void properties of the high-redshift universe with those at lower redshifts, which are better known.  相似文献   

Effects of quasar feedback in galaxy groups     

Suman Bhattacharya  Tiziana Di Matteo  Arthur Kosowsky 《Monthly notices of the Royal Astronomical Society》2008,389(1):34-44

We study the effect of quasar feedback on distributions of baryons in galaxy groups using high-resolution numerical simulations. We use the entropy-conserving gadget code that includes gas cooling and star formation, modified to include a physically based model of quasar feedback. For a sample of 10 galaxy group-sized dark matter haloes with masses in the range of  1–5 × 10¹³ M_⊙  h ⁻¹  , star formation is suppressed by more than 50 per cent in the inner regions due to the additional pressure support by quasar feedback, while gas is driven from the inner region towards the outer region of the haloes. As a result, the average gas density is 50 per cent lower in the inner region and 10 per cent higher in the outer region in the simulation, compared to a similar simulation with no quasar feedback. Gas pressure is also higher in the outer region, while temperature and entropy are enhanced in the inner region. The total group gas fraction in the two simulations generally differs by less than 10 per cent. We also find a small change of the total thermal Sunyaev–Zeldovich distortion, leading to 10 per cent changes in the microwave angular power spectrum at angular scales below 2 arcmin.  相似文献   

Earthquake early warning feasibility in the Campania region (southern Italy) and demonstration system for public school buildings     

Antonio Emolo  Matteo Picozzi  Gaetano Festa  Claudio Martino  Simona Colombelli  Alessandro Caruso  Luca Elia  Aldo Zollo  Piero Brondi  Nicola Miranda 《Bulletin of Earthquake Engineering》2016,14(9):2513-2529

We present the results of a feasibility study of an earthquake early warning system (EEWS) for the Campania region (southern Italy) using schools as specific targets. The study considered the seismogenic zones as sources of potential earthquakes for the area, the Italian accelerometric network as the recording network for seismic event occurrence, and the performances of the software platform PRESTo ^Plus for data analysis and processing. We analyze the distribution of lead-times for all possible threatening seismic sources for each municipality in the region under study by extracting the lead-time value corresponding to the 5th, 10th and 25th percentiles of the distributions. We discuss the results for the 5th percentile in order to analyze the worst-case scenario: in the case of a single site, the lead-time is expected to be larger than this value in the 95 % of the cases. Since the population distribution in Campania is uneven and most of the people live nearby the coast, whilst the most destructive earthquakes occur along the Apennine chain, we can conclude that an efficient EEWS can allow most of the schools in the area to undertake some mitigating actions. The testing of the EEWS was carried out in the high school ITIS ‘E. Majorana’, located at Somma Vesuviana, about 80 km from the seismogenic Irpinia region. For this purpose, the Sentinel, an actuator made up of low-cost hardware (i.e., Arduino^®), was developed in close cooperation with students and teachers of the school to receive alert messages from the PRESTo ^Plus platform and warn the school users in case of a seismic event. The EEWS and the Sentinel were successfully tested during some blind drills performed during normal school activities.  相似文献