Shell‐shape and morphometric variability in Mytilus galloprovincialis from micro‐tidal environments: responses to different hydrodynamic drivers          下载免费PDF全文

Vanessa Moschino  Monica Bressan  Luigi Cavaleri  Luisa Da Ros 《Marine Ecology》2015,36(4):1440-1453

Tidal conditions differently influence inter‐tidal organisms in terms of general physiological and metabolic responses. In this study we investigated the morphological response in shells of Mytilus galloprovincialis native to different micro‐tidal coastal environments in the Northern Adriatic Sea. Our purpose was to highlight the ecophenotypic variability across tidal levels and to elucidate how tidal currents and waves produced by anthropogenic activities may play a part in modulating shell morphology. Three sampling sites were selected: an open‐sea area 15 km off‐shore and two sites within the lagoon of Venice, the first near one of its three inlets, and the other one in the proximity of Venice city centre. At each sampling site, organisms were seasonally collected at different depths within their vertical zonation, either in the inter‐tidal zone – i.e. at both the highest and lowest tide zonation limits, and subtidally. The mussel shells were analysed by investigation of their morphometric relationships (height/length and width/length ratios) and by elliptic Fourier analysis of the shell contours. Shell thickness and condition index were also evaluated for a better comprehension of energy allocation/partitioning. Estimates based on long‐term measurements, visual observation, wind statistics and wave growth laws allowed an evaluation of the forces acting on shells. At the open‐sea site, the observed phenotypic variability of both shell shape and thickness was clearly related to the tidal vertical zonation. At the two lagoon sites, the currents generated by tidal flow through the inlet and the waves caused by the frequent passage of boats influenced both shell shape and thickness. A trade‐off between protection and growth was apparent along the tide gradient, as emphasized by the differences in the partitioning and allocation of energy between shell and flesh production.  相似文献   

Drought tolerant maize for farmer adaptation to drought in sub-Saharan Africa: Determinants of adoption in eastern and southern Africa   总被引：2，自引：1，他引：1  

Monica Fisher  Tsedeke Abate  Rodney W. Lunduka  Woinishet Asnake  Yoseph Alemayehu  Ruth B. Madulu 《Climatic change》2015,133(2):283-299

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An attempt to test Ambartsumian's idea of the origin of the galaxy . II. location of galaxies within clusters and galaxy position angles     

H. A. Harutynyan  Monica Biernacka  Piotr Flin 《Astrophysics》2010,53(1):42-49

The location of galaxies in 377 rich Abell galaxy clusters is discussed. We compared the distributions of galaxies in the sample containing all galaxies with the sample compiled from the 20 brightest objects. Counts in circular sectors with angle width equal to 30î show isotropy. Only in the case of BM I clusters and the coordinate system related to the cluster major axis did we find anisotropic distributions. We investigated also the distributions of galaxy position angles within clusters exhibiting isotropy. The structure position angles for both samples have been studied as well. They appeared to be different. The difference in location of galaxies in the case of cD clusters, as well as the more elliptical shape and different position angles of samples containing bright galaxies is observed.  相似文献   

Marine debris review for Latin America and the wider Caribbean region: from the 1970s until now, and where do we go from here?   总被引：1，自引：1，他引：0  

Ivar do Sul JA  Costa MF 《Marine pollution bulletin》2007,54(8):1087-1104

The available literature on marine debris from Latin America and the Wider Caribbean Region was collected and linked, reviewing their methodologies and principal results (quantities, composition and spatial-temporal patterns). The study region comprises 52 coastal countries of which only 14 had registers of works on marine debris. A total of 70 works were available and 69 had their full contents accessed. Brazil dominated the available literature with 70% of the documents. Beaches were the most studied environment, and plastics the prevalent form of contamination in the whole region. The exposure of marine biota (species, type of contact, consequences) was highlighted. The studied region, although still little exploited by this sort of research, shows the same contamination patterns observed world-wide. We also contacted 40 researchers in the area, collecting scientific contributions, opinions and suggestions for improvement of this research field. Further advances and new (urgently needed) lines of research are also discussed.  相似文献   

Sulfur Concentration in Geochemical Reference Materials by Solution Inductively Coupled Plasma‐Mass Spectrometry     

Monica E. Erdman  Cin‐Ty A. Lee  Wenbo Yang  Lynn Ingram 《Geostandards and Geoanalytical Research》2014,38(1):51-60

With implications for the origin of ore deposits, redox state of the atmosphere, and effects of volcanic outgassing, understanding the sulfur cycle is vital to our investigation of Earth processes. However, the paucity of sulfur concentration measurements in silicate rocks and the lack of well‐calibrated reference materials with concentrations relevant to the rocks of interest have hindered such investigations. To aid in this endeavour, this study details a new method to determine sulfur concentration via high mass resolution solution inductively coupled plasma‐mass spectrometry (ICP‐MS). The method is based on an aqua regia leach, involving relatively rapid sample preparation and analysis, and uses small test portion masses (< 50 mg). We utilised two independently prepared standard solutions to calibrate the analyses, resulting in 4% accuracy, and applied the method to eight geochemical reference materials. Measurements were reproducible to within ~ 10%. Sulfur concentrations and isotopes of six reference materials were measured additionally by elemental analyser‐combustion‐isotope ratio mass spectrometry to independently evaluate the accuracy of the ICP‐MS method. Reference materials that yielded reproducible measurements identical to published values from other laboratories (JGb‐1, JGb‐2 and MAG‐1) are considered useful materials for the measurement of sulfur. Reference materials that varied between studies but were reproducible for a given test portion perhaps suffer from sample heterogeneity and are not recommended as sulfur reference materials.  相似文献   

Pullout Response of Uniaxial Geogrid in Tire Shred–Sand Mixtures     

Umashankar Balunaini  Sungmin Yoon  Monica Prezzi  Rodrigo Salgado 《Geotechnical and Geological Engineering》2014,32(2):505-523

Use of tire shred–soil mixtures as backfill materials in mechanically stabilized earth walls has several advantages over other backfill materials: (1) good drainage, (2) high shear strength, and (3) low compacted unit weight. This paper presents the results of laboratory pullout tests performed on uniaxial geogrid embedded in tire shred–sand mixtures. The effects of tire shred size, tire shred–sand mixing ratio and confining pressure on the interaction between the geogrid and tire shred–sand mixtures are evaluated. Three sizes of tire shreds are considered: tire chips (with 9.5 mm nominal size), tire shreds 50-to-100 mm long and tire shreds 100-to-200 mm in length, with mixing ratios of 0, 12, 25 and 100 % of tire shreds in the mixtures (by weight). Based on compaction testing of a number of mixtures, the optimal mixing proportion of tire shreds and sand was found to lie between 25/75 and 30/70 (by weight of tire shred and sand); this is equivalent to approximately 40/60 and 50/50, respectively, by volume of tire shreds and sand. The pullout resistance of a geogrid embedded in tire shred–sand mixtures is significantly higher than that of the same geogrid embedded in tire shreds only. The size of the tire shreds has negligible effect on the pullout resistance of a geogrid embedded in mixtures prepared with either low (12/88 mix) or high (100/0 mix) tire shred content. However, when the 25/75 mixture is used, greater geogrid pullout resistance was obtained for the geogrid embedded in tire chip–sand mixtures than in tire shred–sand mixtures.  相似文献   

Here, there and everywhere. Small plastic fragments and pellets on beaches of Fernando de Noronha (Equatorial Western Atlantic)     

Juliana A. Ivar do Sul  Ângela Spengler  Monica F. Costa 《Marine pollution bulletin》2009,58(8):1236-1238

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The XMM-Newton Bright Serendipitous Survey: First Extragalactic Results     

Tommaso Maccacaro  Roberto Della Ceca  Valentina Braito  Alessandro Caccianiga  Paola Severgnini  Anna Wolter 《Astrophysics and Space Science》2004,294(1-2):89-94

We present here some initial results from the ongoing XMM-Newton bright serendipitous survey. The survey is aimed at selecting and spectroscopically identifying a large and statistically representative sample of bright (f _x ≳ 7× 10⁻¹⁴ c.g.s) serendipitous X-ray sources in the 0.5–4.5 keV energy band (BSS) and a complementary (smaller) sample in the 4.5–7.5 keV energy band (HBSS). The work is partly based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributors directly founded by ESA member states and the USA(NASA) and on observations collected at TNG. The TNG telescope is operated on the island of La Palma by the Centro Galileo Galilei of the INAF in the Spanish Observatorio del Roque de Los Muchachos of the Instituto de Astrofísica de Canarias. On behalf of the XMM-Newton Survey Science Center.  相似文献   

The collapse of primordial stars: importance of radiation     

Francesco Haardt  Emanuele Ripamonti  Monica Colpi  Andrea Ferrara 《Astrophysics and Space Science》2002,281(1-2):479-482

We simulate the collapse of a primordial protostellar cloud by means of a 1D hydrodynamics code accounting for chemical evolution, radiative transfer and radiation pressure. We find that the role of radiation pressure is negligible throughout the whole simulations, i.e. Until shortly after the formation of a central hydrostatic core. We also estimate the luminosity and the spectrum of such collapsing clouds. The luminosity is initially due to a number of H₂ lines and is of the order of 10^33-34 erg s^-1. It then grows to values ≳10³⁶ erg s^-1 by the time the core forms, and results from both HH lines and continuum radiation. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

Laboratory tests with interferometric optical fibre sensors to monitor shallow landslides triggered by rainfalls     

Longoni  Laura  Ivanov  Vladislav  Ferrario  Maddalena  Brunero  Marco  Papini  Monica  Arosio  Diego 《Landslides》2022,19(3):761-772

Optical fibre–based sensors have now established their place in the field of geohazard monitoring due to their sensitivity to strain and temperature changes. Progressive development in the technology leads to the availability of novel, accurate and durable sensors at a relatively limited cost. This creates room for original monitoring applications that have been, so far, impeded by the shortcomings of conventional monitoring tools. In this work, we explore the applicability of an interferometric optical fibre sensor as a vibration sensing tool at laboratory scale. We tested the ability of the sensor to identify precursors of instability in a downscaled model of a rainfall-induced landslide composed of granular material. We carried out four experimental tests which involved different sensor deployments and soil mixtures. The recorded signals were processed by means of a time–frequency analysis and we identified two frequency-domain parameters—the spectral centroid and band power—that could provide information on the development of instability. Their ratio yielded a unique parameter through which a precursory stage could be outlined by defining a threshold value based on the data collected at the beginning of the experiment. In our lab tests, precursors of instability were detected 2–3 min before a crack was observed at the surface. This may upscale to a lead time of about 20–30 min or more in the field, classifying our monitoring approach in between an alarm and a warning system. The work presented here can be considered a first promising step towards an innovative monitoring system and shows the potential of optical fibre sensing as a shallow landslide monitoring technique, encouraging further testing, especially in real-case studies.

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