Search

We present the results of the tephrochronology study of a 14.49 m long marine sediment core (TR 17–08) collected in the Edisto Inlet, Ross Sea (Antarctica). The core contains four cryptotephra layers at 55–56, 512–513, 517–518, and 524–525 cm of depth, which have been characterised by a detailed description of the texture, mineral assemblage, and single glass shards major and trace element geochemistry. The age model of the investigated sedimentary sequence, based on radiocarbon dating, indicates that the topmost cryptotephra correlates with the widespread 1254 CE tephra erupted by a historical eruption (696 ± 2 cal yrs BP) of Mount Rittmann, in northern Victoria Land. Deeper cryptotephra layers were derived from previously unknown explosive eruptions of Mount Melbourne volcano and were emplaced between 1615 cal yrs BP and 1677 cal yrs BP, e.g. between the 3rd and 4th centuries CE. This discovery demonstrates that the Mount Melbourne volcanic complex has been highly active in historical times allowing significant progress in the current understanding of regional eruptive history. Moreover, from a tephrochronological point of view, the detected cryptotephra provide new regional isochron markers to facilitate high-precision correlations and help stratigraphically constrain changes in environmental and climatic conditions that are identified by multidisciplinary studies.

A multiproxy study combining paleomagnetic, rock magnetic (magnetic susceptibility; anhysteretic remanent magnetization, ARM; isothermal remanent magnetization, IRM, anisotropy of magnetic susceptibility, AMS) and geochemical (XRF) data was carried out on trench sediments collected in the area of Boca do Rio (Algarve, South Portugal) known to have been stricken by a tsunami wave related to the 1755 Lisbon earthquake. The magnetic mineral assemblage is dominated by multidomain ferrimagnetic grains with a significant contribution (5–9%) of ultra-fine magnetic particles related to the presence of pedogenetic magnetite. The variable amount of this post-depositional magnetite plays a role on the characteristic remanent magnetization (ChRM) of the sediment. The primary magnetization recorded at T1, located farthest from the coast, is representative of the paleosecular variation of the Earth's magnetic field and a comparison of the results with the regional model for the geomagnetic field in Europe (SCHA.DIF.3K) was used to constrain the erosional signature of the tsunami layer. The result indicates that less than eighty years could be missing in the sedimentary column. The eroded sediment (thickness 27–40 cm) was incorporated in the tsunami layer that is characterized by a low magnetic content and a large increase in the Ca content representing allochthonous material. Sedimentological, geochemical, magnetic and AMS data show that the signature of the tsunami layer reflects at least two waves with an erosive capacity that is controlled by the distance from the shore.

The development of ultra-bright extreme ultraviolet (EUV) and X-ray free electron laser (FEL) sources has enabled the extension of wave-mixing approaches into the short wavelength regime. Such a class of experiments relies upon nonlinear interactions among multiple light pulses offering a unique tool for exploring the dynamics of ultrafast processes and correlations between selected excitations at relevant length and time scales adding elemental and site selectivity as well. Besides the availability of a suitable photon source, the implementation of wave mixing methodology requires efforts in developing the instrumental set-up. We have realized at the FERMI FEL two dedicated set-ups to handle multiple FEL beams with preselected parameters in a non-collinear fashion and control their interaction sequence at the target. These unique apparatuses, combined with the exceptional characteristics of the seeded FERMI FEL, have allowed us to make the first steps into this field and further advances are foreseen in the near future.

Trace Metals (TMs: Pb, Zn, Cu, Cr, Cd, and Ni), major elements (Al and Fe) and radionuclides (

Lightweight nested parallelism support for NUMA embedded many-cores is proposed.SW- and HW-accelerated solutions are explored and integrated in OpenMP.Implementation is provided on a real manycore (STMicroelectronics STHORM).We achieve 28 speedup VS flat parallelism on several real embedded applications. Embedded manycore architectures are often organized as fabrics of tightly-coupled shared memory clusters. A hierarchical interconnection system is used with a crossbar-like medium inside each cluster and a network-on-chip (NoC) at the global level which make memory operations nonuniform (NUMA). Due to NUMA, regular applications typically employed in the embedded domain (e.g., image processing, computer vision, etc.) ultimately behave as irregular workloads if a flat memory system is assumed at the program level. Nested parallelism represents a powerful programming abstraction for these architectures, provided that (i) streamlined middleware support is available, whose overhead does not dominate the run-time of fine-grained applications; (ii) a mechanism to control thread binding at the cluster-level is supported. We present a lightweight runtime layer for nested parallelism on cluster-based embedded manycores, integrating our primitives in the OpenMP runtime system, and implementing a new directive to control NUMA-aware nested parallelism mapping. We explore on a set of real application use cases how NUMA makes regular parallel workloads behave as irregular, and how our approach allows to control such effects and achieve up to 28 speedup versus flat parallelism.

Background: The COVID-19 pandemic (C19P) is causing several detrimental effects on cancer care globally. CT are crucial to obtain high quality literature evidence and “poor accrual” is the most common reason for their early discontinuation (ED). At our best knowledge, no data are available on ED of cancer CT after the beginning of C19P. Methods: ClinicalTrial.gov was queried for terminated (T), withdrawn (W) and suspended (S) CT for the following terms: “cancer”, “neoplasm”, and “tumor”. The search was made for all the CT available from the inception to 26th February 2021, without any restrictions. The following characteristics were extracted: reason for ED, study type (interventional [In] vs observational), sponsored (yes vs not). ED rate was compared between CT discontinued for C19P or not (χ2);p

Soft x-rays were applied to induce graphitization of diamond through a non-thermal solid-to-solid phase transition. This process was observed within poly-crystalline diamond with a time-resolved experiment using ultrashort soft x-ray pulses of duration 52.5 fs and cross correlated by an optical pulse of duration 32.8 fs. This scheme enabled for the first time the measurement of a phase transition on a timescale of ~150 fs. Excellent agreement between experiment and theoretical predictions was found, using a dedicated code that followed the non-equilibrium evolution of the irradiated diamond including all transient electronic and structural changes. These observations confirm that soft x-rays can induce a non-thermal ultrafast solid-to-solid phase transition on a hundred femtosecond timescale., Comment: 27 pages, 17 figures (includes supplementary materials)

Transverse ridges are large topographic anomalies running adjacent to slow-slip oceanic transforms. They form due to different processes, including thermal stresses, hydration-dehydration of peridotites, non-linear viscoelastic rheology of the oceanic crust and vertical tectonic motions of lithospheric slivers induced by changes in ridge/transform geometry, causing transpression and/or transtension along the transform boundary. A prominent transverse ridge on the southern side of the Vema transform (Central Atlantic) rose probably between 12 and 10 Ma along the entire length (approximate to 320 km) of the transform, exposing a relatively undisturbed section of oceanic lithosphere. We used pelagic limestones encrusting serpentinized peridotites sampled from the lower slopes of the uplifted lithospheric section to date this uplift and define mechanisms of its emplacement. Ages were obtained both by micropaleontology (foraminifera and nannofossils) and by Sr-87/Sr-86 isotope ratios. No ages older than 12 Ma were obtained, even in samples recovered at sites with crustal ages (determined by magnetic anomalies) well over 12 Ma; on the other side, ages as young as 5.6-83 Ma were found in clusters of samples collected from the eastern part of the transverse ridge, probably due to mass-wasting episodes that rejuvenated the substratum. These results support the hypothesis that the Vema Transverse Ridge rose between 12 and 10 Ma due to flexural uplift related to transtension along the transform, in line with a general model whereby transverse ridges rise during discrete events as a consequence of changes in ridge-transform geometry. (C) 2017 Elsevier B.V. All rights reserved.

A sequence of tephra layers is studied in a 13.9 m-long deep-sea core (MD01-2474G) from the southern Tyrrhenian Sea. The chronology of the succession is provided by a high-resolution age-depth model based on isotope stratigraphy and AMS radiocarbon dating, which place the succession of events in a time interval spanning the last 70 ka. Based on a precise chronological framework and proximal-distal correlations, the Y-1, Y-6 and Y-7 main marker tephras were identified. Compositional data on fresh micro-pumice or glass shards of selected tephras were correlated with the coeval volcanic activity of Aeolian Arc (Vulcano and Salina), Mt. Etna, Phlegrean Fields Pantelleria and Ischia. The tephra sequence contains a number of deposits documenting recurrent activity on Vulcano Island at ca. 6.9 ka BP (MD3), ca. 16.7 ka BP (MD11), ca. 23.2 ka BP (MD14), ca. 29.6 ka BP (MD15), ca. 36.9 ka BP (MD22) and ca. 42.5 ka BP (MD27). The results presented in this study improve the southern Tyrrhenian Sea tephrostratigraphic framework and provide new insights into chemistry and dispersal area of Aeolian Arc pyroclastic deposits in this sector of the Central Mediterranean.

Marine ecosystem forecasting is an area of active research and rapid development. Promise has been shown for skillful prediction of physical, biogeochemical, and ecological variables on a range of timescales, suggesting potential for forecasts to aid in the management of living marine resources and coastal communities. However, the mechanisms underlying forecast skill in marine ecosystems are often poorly understood, and many forecasts, especially for biological variables, rely on empirical statistical relationships developed from historical observations. Here, we review statistical and dynamical marine ecosystem forecasting methods and highlight examples of their application along U.S. coastlines for seasonal-to-interannual (1–24 month) prediction of properties ranging from coastal sea level to marine top predator distributions. We then describe known mechanisms governing marine ecosystem predictability and how they have been used in forecasts to date. These mechanisms include physical atmospheric and oceanic processes, biogeochemical and ecological responses to physical forcing, and intrinsic characteristics of species themselves. In reviewing the state of the knowledge on forecasting techniques and mechanisms underlying marine ecosystem predictability, we aim to facilitate forecast development and uptake by (i) identifying methods and processes that can be exploited for development of skillful regional forecasts, (ii) informing priorities for forecast development and verification, and (iii) improving understanding of conditional forecast skill (i.e., a priori knowledge of whether a forecast is likely to be skillful). While we focus primarily on coastal marine ecosystems surrounding North America (and the U.S. in particular), we detail forecast methods, physical and biological mechanisms, and priority developments that are globally relevant.

A one-dimensional ecosystem numerical model is used to simulate the ecosystem changes that could have occurred in the open ocean areas of the Eastern Mediterranean Sea during the Climatic Optimum interval (9500-6000 B.P., Mercone et al. [Mercone, D., Thomson, J., Croudace, I.W., Siani, G., Pateme, M., Troelstra, S., 2000. Duration of S1, the most recent sapropel in the eastern Mediterranean Sea, as indicated by accelerator mass spectrometry radiocarbon and geochemical evidence. Paleoceanography 15, 336-347]). In this period the S1 sapropel was deposited. S1 is the most recent sapropel in the succession of organic carbon-rich layers intercalated in normal Neogene sedimentary sequences. Different theories have been invoked in order to explain the deposition of this peculiar layer. Our simulations seem to indicate that the modified thermohaline circulation, supplying oxygen only in the first 500 m of the water column, is responsible for the sapropel deposition when higher productivity is allowed in the euphotic zone. The model shows the importance in this process of bacteria that consume oxygen by decomposing the Particulate Organic Matter (POM) produced in the upper water column. The sinking velocity of POM partially regulates the timescale of the occurrence of anoxia at the bottom and in the whole water column, allowing the relatively rapid onset of sapropel deposition. (c) 2005 Elsevier B.V. All rights reserved.

El Nino-Southern Oscillation (ENSO) is recognized as one of the potentially predictable drivers of California Current System (CCS) variability. In this study, we analyze a 67-year coarse-resolution ( ∼ 1°) simulation using the ocean model CESM-POP2-BEC forced by NCEP/NCAR reanalysis winds to develop a model composite of the physical–biological response of the CCS during ENSO events. The model results are also compared with available observations. The composite anomalies for sea surface temperature (SST), pycnocline depth, 0m-100m vertically averaged chlorophyll, 0m-100m vertically averaged zooplankton, 25m-100m vertically averaged nitrate, and oxygen at 200m depth exhibit large-scale coherent relationships between physics and the ecosystem, including reduced nutrient and plankton concentrations during El Nino, and increased nutrient and plankton concentrations during La Nina. However, the anomalous model response in temperature, chlorophyll, and zooplankton is generally much weaker than observed and includes a 1–2 month delay compared to observations. We also highlight the asymmetry in the model CCS response, where composite model La Nina events are stronger and more significant than model El Nino events, which is a feature previously identified in observations of CCS SST as well as in tropical Pacific Nino-4 SST where atmospheric teleconnections associated with ENSO are forced. These physical–biological composites provide a view of some of the limitations to the potentially predictable impacts of ENSO teleconnections on the CCS within the modeling framework of CESM-POP2-BEC.

The Palermo and Augusta urban/industrial areas (Sicily) are examples of contaminated coastal environments with a relatively high influx of unregulated industrial and domestic effluents. Three sediment box-cores were collected offshore of these urban/industrial areas in water depths of 60-150 m during two cruises (summers 2003/2004), dated by (210)Pb and (137)Cs, and analysed for total mercury concentration and total polycyclic aromatic hydrocarbon (PAH) concentration. Benthic foraminiferal assemblages were also examined (in terms of their distribution and morphology) to assess the potential use of benthic foraminifera as bioindicators of pollutant input and environmental change in these Mediterranean shelf environments. The Hg and PAHs vs depth profiles show a clear increase in concentration with decreasing depth. Most of the sediments are highly enriched in mercury and show concentrations more than 20 times the background mercury value estimated for sediments from the Sicily Strait. The Hg and PAH concentrations appear to be potentially hazardous, grossly exceeding national and international regulatory guidelines. A reduction in abundance of benthic foraminifera, increasing percentages of tests with various morphological deformities, and the dominance of opportunistic species in more recent sediments can be correlated to anthropogenic impact.

Calcareous nannoplankton, diatoms and organic-walled dinoflagellate cysts from seven eastern Mediterranean sediment cores were investigated to clarify the climatic and paleoceanographic conditions that influenced the deposition of sapropel S5 during Marine Isotopic Stage 5e. Warming of surface waters during S5 deposition is indicated by the high abundance of the calcareous nannofossil "small" Gephyrocapsa group, the presence of the dinoflagellate species Spiniferites mirabilis, Spiniferites pachydermus, Lingulodinium machaerophorum and Polysphaeridium zoharyi, and the tropical-subtropical diatom Pseudosolenia calearavis, Chaetoceros resting spores, Rhizosolenids and Thalassionema group. Increased productivity accompanied S5 deposition as evidenced by a general decrease in abundance of calcareous nannofossil superficial species and a coeval increase of dinocysts and diatoms. The productivity increase is further supported by an increase of the deep dwelling calcareous nannofossil species Florisphaera profunda. Stratification of near-surface waters is recorded by the presence of the dinocyst species L. machaerophorum and P zoharyi together with the co-occurrence of the diatom Chaetoceros resting-spore group, Thalassionema frauenfieldii, and Thalassionema nitzschioides var. parva, which reflect transport of neritic waters off-shore, and by the presence of some freshwater and transport-related diatom taxa (Cyclotella, Diatomella and Diploneis). Gradual shoaling of the nutricline and a gradual weakening of water stratification at the end of S5 deposition is indicated by an increase in the deep dwelling calcareous nannoplankton species Gladiolithus flabellatus, which suggests a less-deep niche compared to the deeper dwelling F profunda. Time transgressive variations in the distribution of the calcareous nannofossil Emiliana huxleyi and changes in the abundances of Gephyrocapsa oceanica, small Gephyrocapsa, G. flabellatus, and of the dinocysts R zoharyi and L. machaerophorum lead to paleocirculation considerations, as they always reflect the main current path. Moreover, the occurrence of upwelling-related diatom and dinocyst taxa, such as Chaetoceros resting spores and S. pachydermus, suggests the presence of a former gyre structure south of Crete that was active during S5 time. (c) 2005 Elsevier B.V. All rights reserved. Accession Number: WOS:000238018900003

Detailed analyses of modern and fossil benthic foraminiferal assemblages collected in the central Adriatic Sea are used as tools to reconstruct the environmental changes that occurred between the Last Deglaciation and the Present (last 14 Kyrs); in particular we focus on the timing and formation of the mud-belt. The modern benthic foraminiferal assemblages display a parallel zonation to the Italian coast controlled by the interaction between food/oxygen availability and water depth. Cluster analysis of 4 sediment cores separates the fossil foraminiferal assemblages in 6 groups: Cluster A is dominated by three Ammonia species; Cluster B consists of Ammonia papillosa, Nonionella turgida, Elphidium advenum and Elphidium decipiens; Cluster C is composed of two taxa, Hyalinea balthica and Trifarina angulosa; Cluster D is dominated by 5 species, Cibicides lobatulus, Buccella granulata, Reussella spinulosa, Textularia agglutinans and Elphidium crispum; Cluster E contains Bulimina spp., Gavelinopsis praegeri, Bolivina spp., Cassidulina neocarinata and Asterigerinata mamilla; and Cluster F is dominated by Bulimina marginata, Valvulineria bradyana, Globocassidulina subglobosa and Melonis padanum. The cluster analysis and contemporary distribution patterns of these taxa are used together with ecological preferences of the most frequent species to reconstruct the spatial and temporal distribution of the different biofacies in the past. This reveals information about Holocene palaeoenvironmental changes that are related to water depth fluctuations and the installment of the coast-parallel mud-belt. The benthic assemblage records the transition from a infralitoral environment (Biofacies I) to deeper marine condition (Biofacies III). After that the sea level reached about the modern level (Biofacies IV) the benthic foraminiferal community evidences the development of the mud-belt and the subsequent transformation of the ecological niches linked to the trophic evolution of the environment.

We have investigated the scattering mechanisms limiting the low-temperature electron mobility in unintentionally doped In 0.75 Al 0.25 As/In 0.75 Ga 0.25 As metamorphic quantum wells grown on GaAs (0 0 1) substrates. We found that the mobility is limited by background impurity scattering for densities lower than 2.0×10 11 cm −2 , and by the combination of this mechanism and alloy disorder scattering for higher densities. From such analysis we estimate an alloy disorder scattering potential of about 0.5±0.1 eV. Moreover we show that when a strained InAs layer is located in the centre of the In 0.75 Ga 0.25 As well, the alloy disorder scattering can be reduced, yielding mobilities up to 320 000 cm 2 /Vs at a carrier concentration of 3.1×10 11 cm −2 .

Integrated high resolution data from calcareous plankton assemblages (foraminifera and nannofossils) together with geochemical and mineralogical investigations have been collected at the on-land Montalbano Jonico section (southern Italy) in order to reconstruct the paleoenvironmental changes through Marine Isotope Stages (MIS) 23–37. Time-series analysis on Globigerina bulloides and Cassidulina carinata δ18O records and on selected calcareous plankton proxies mainly revealed the occurrence of precession and obliquity forcing. The deposition of sapropel layers, which are interbedded in the Montalbano Jonico section, was driven by water column stratification (insolation cycle i-104) and enhanced sea surface water productivity (insolation cycle i-112, i-102 and i-86). Different paleoenvironmental conditions mark the sedimentary evolution of the section. From 1240 to 1082 ka (MIS 37–MIS 32), high percentage abundances of warm and oligotrophic planktonic foraminifera and calcareous nannofossil taxa indicate the establishment of oligotrophic and stratified surface water conditions. A key paleoenvironmental change occurred during MIS 31 (from about 1080 to 1065 ka), which was a very warm interglacial characterized by an increase of tropical–subtropical (Globigerinoides ruber group and Globigerinoides trilobus) and low salinity (Braarudosphaera bigelowii) sea surface water taxa. During this interval, more humid climate conditions coupled with changes in local paleomorphology may have triggered a higher and unusual freshwater input and the creation of a new entry point for sediment supply into the basin from a different drainage area. From about 1065 to 1010 ka (MIS 30–MIS 29), a cool and dry climate prevailed in the circum-Mediterranean area during a time of precession maxima. This favored lowered sea surface temperatures and an increase of polar-water Neogloboquadrina pachyderma left coiling. There are also indications of a reduction of the terrigenous input from the new source area. From 1010 ka upward (MIS 28–MIS 23), the higher abundances of Globigerina bulloides, Turborotalita quinqueloba and Calciosolenia spp. indicate enhanced productivity conditions probably related to high turbidity of sea surface waters triggered by a more conspicuous sediment input from land. Analysis of the long-term trends in the multiproxy patterns suggests that the major paleoenvironmental changes occurred as a consequence of the combined effect of orbitally-controlled global climate and regional processes.

An instrumented mooring line with sediment traps, current meters and recorders of temperature and conductivity was deployed just south of the Antarctic Polar Front (63° 26′ S, 178° 03′E; water depth 4400 m) from January 9th 1999 to January 10th 2000. Sediment traps at 900 and 3700 m had a single large cup to collect particulate material throughout the 1-year study whereas time-series sediment traps were used to characterize the temporal variability at 1300 and 2400 m. Samples were characterized via several parameters including total mass flux, elemental composition (organic carbon, total nitrogen, biogenic silica, and calcium carbonate), concentration of metals (aluminum, iron, barium, and manganese), 210Pb activity, and foraminifera identification. High vertical fluxes of biogenic particles were observed in both summer 1999 and 2000 as a result of seasonal algal blooms associated with sea ice retreat and water column stratification. During autumn and winter, several high energy events occurred and resulted in advecting resuspended biogenic particles from flat-topped summits of the Pacific Antarctic Ridge. Whereas the distance between seabed and uppermost sediment traps was sufficient to avoid lateral advection processes, resuspension was significant in the lowermost sediment traps accounting for ~ 60 and ~ 90% of the material caught at 2400 and 3700 m, respectively. Although resuspended material showed an elemental composition relatively similar to vertical summer fluxes, samples collected during high energy events contained benthic foraminifera and exhibited significantly higher 210Pb activity indicating a longer residence time in the water column. In addition, during quiescent periods characterized by low mass fluxes, the content of lithogenic particles increased at the expense of phytodetritus indicating the influence of material advected through the benthic nepheloid layer. Organic matter content was particularly high during these periods and showed statistically significant linear correlations with metals suggesting adsorption of organic coatings onto the mineral surface of lithogenic particles.

Two deep-sea cores (ANTA95-157 and ANTA98-1) were collected in the Pacific sector of the Southern Ocean across the present-day position of the Antarctic Polar Front Zone (APFZ) to document paleoenvironmental changes during the last 2.60 Ma. The stratigraphic framework was established using a combination of diatom marker species, Accelerator Mass Spectrometry (AMS) 14 C datings, magnetostratigraphy, and oxygen stable isotopes. The study was based on carbon and nitrogen isotopes of diatom-bound organic matter, dry bulk density, magnetic susceptibility, carbonates and biogenic silica contents. Large continental inputs were recorded during glacial periods and major iceberg melting occurred at 2.45 Ma and during the Middle Pleistocene Revolution (MPR) time interval. Diatom production increased during the Early Pleistocene and remained significant ever since, with the exception of the MPR period and immediately before. Lower glacial diatom productivity linked to higher nitrogen utilization might have characterized the period between Marine Isotope Stages (MISs) 15–13 (0.6 and 0.5 Ma), whereas succeeding glacial stages experienced an increase of diatom productivity promoted by the inflow of nutrient-rich deep waters. The low diatom production observed during interglacial stage 11 could be explained with a southward shift (up to 4°) of the Polar Front (PF) with respect to its present position. Paleoproductivity levels have been confirmed as lower than those measured in other sectors of the Southern Ocean, with reduced differences among glacial and interglacial stages.

In order to determine the factors controlling the distribution of planktonic foraminifera as a proxy for reconstruction of paleoenvironments, we present data on live assemblages collected in the Southern Ocean. Plankton tows and hydrographic measurements were taken in the upper 400 m of the water column at different sites in the Ross Sea (site B) and at the Polar Front of the Pacific Ocean (site O) during austral summers from 1998 to 2003. Based on qualitative micropaleontological observations we discriminated between Neogloboquadrina pachyderma dextral (dex) and N. pachyderma sinistral (sin). In addition for N. pachyderma (sin) we distinguished four morphs: the first one (1) has a thickened test and depressed sutures; the second morph (2) is represented by specimens characterized by a subspheric and heavily encrusted test; the third morph (3) has a thin and lobate walled test; the fourth one (4) represent the juvenile stage of N. pachyderma (sin) and is characterized by a smaller average size. The microfauna collected in the Ross Sea (site B) is characterized by the dominance of N. pachyderma (sin) (morphs 1 and 2), whereas low occurrences of Turborotalia quinqueloba, N. pachyderma (dex) and Neogloboquadrina dutertrei were noted in the first 50 m of the water column. The water column at this station is characterized by a marked and shallow stratification and a marked thermocline during the sampling season. At the ocean station (site O), the assemblage shows increasing diversification: T. quinqueloba , G. bulloides, N. pachyderma (dex) and few specimens of Globigerinita uvula characterize the planktonic microfauna. There is a predominance of non-encrusted morphs and juvenile specimens (3 and 4). At this station the mixed surface layer is deeper than in the Ross Sea (60–70 m), the pycnocline and the thermocline less marked. The depth and the intensity of the Deep Chlorophyll Maximum (DCM) influence foraminiferal distribution: N. pachyderma (sin) shows abundance peaks at or just below the DCM while G. bulloides peaks above the DCM. Coiling direction of N. pachyderma seems to be not controlled exclusively by Sea Surface Temperature (SST): probably the two coiling types are genetically different. Results document that diversity of planktonic foraminifera, number of specimens and variations in test morphology are related to regional differences in water properties (temperature, salinity, and DCM depth).

The dynamical link between mean state biases and dominant timescales of interannual variability is examined using the output from two state-of-the-art coupled model simulations, results from an ocean-only simulation forced with observed surface fields, and various observational data sets. The focus of this study is the relative role of the mean upper ocean density structure vs. anomalous wind forcing in controlling the spectral characteristics of tropical Pacific interannual variability. It is shown that an extensive South Pacific Convergence Zone (SPCZ) creates a potential vorticity (PV) barrier in the Southern Hemisphere similar to the one associated with the Intertropical Convergence Zone (ITCZ) in the Northern Hemisphere in both climate models. The PV barrier in the Southern Hemisphere strongly constrains the mean equatorward flow in the ocean model pycnocline, creating a “choke point” for the mean flow around 10°S. It is then examined whether the PV barrier can also limit the anomalous flow associated with mass recharge/discharge to/from the equatorial thermocline at interannual timescales. If the anomalous flow were impeded by the mean PV structure the meridional extent of the area involved in the mass recharge/discharge process would be narrower, leading to a shorter adjustment (and ENSO) timescale. Comparison of the two climate models, both of which have similarly erroneous PV structures in the southern tropical Pacific, but different interannual timescales, shows that the meridional extent of the anomalous meridional transport is primarily controlled by the latitudinal location of the wind stress curl anomalies, while the mean state bias in the Southern Hemisphere does not seem to have any significant influence.

We describe a previously un-reported vertex-negative potential evoked by high intensity click auditory stimuli in some dogs and cats with suspected cochleo-saccular deafness. Brainstem auditory evoked potential tracings from 24 unilaterally or bilaterally deaf animals, 22 dogs and 2 cats, among which 21 belonged to breeds with high prevalence of suspected or histologically confirmed cochleo-saccular deafness, were studied retrospectively. Values for latency, amplitude and threshold of this potential in dogs were 2.15 ± 0.23 ms, 0.49 ± 0.25 μV, and 91.9 ± 4.7 dB NHL, respectively (mean ± SD). Latency and threshold values in cats were in the mean ± 2 SD range of the dog values. Sensitivity to click stimulus polarity and to click stimulus delivery rate pointed towards a neural potential instead of a receptor potential. The vertex-negative wave observed in these animals shares all characteristics with the N3 potential described in some deaf humans with cochlear deafness, where it is presumed to arise from saccular stimulation. The combined degeneration of cochlea and sacculus usually reported in deaf white dogs and cats suggest that N3 may have a different origin in these species.

Tropical Pacific interannual variability is examined in nine state-of-the-art coupled climate models, and compared with observations and ocean analyses data sets, the primary focus being on the spatial structure and spectral characteristics of El Nino-Southern Oscillation (ENSO). The spatial patterns of interannual sea surface temperature (SST) anomalies from the coupled models are characterized by maximum variations displaced from the coast of South America, and generally extending too far west with respect to observations. Thermocline variability is characterized by dominant modes that are qualitatively similar in all the models, and consistent with the “recharge oscillator” paradigm for ENSO. The meridional scale of the thermocline depth anomalies is generally narrower than observed, a result that can be related to the pattern of zonal wind stress perturbations in the central-western equatorial Pacific. The wind stress response to eastern equatorial Pacific SST anomalies in the models is narrower and displaced further west than observed. The meridional scale of the wind stress can affect the amount of warm water involved in the recharge/discharge of the equatorial thermocline, while the longitudinal location of the wind stress anomalies can influence the advection of the mean zonal temperature gradient by the anomalous zonal currents, a process that may favor the growth and longer duration of ENSO events when the wind stress perturbations are displaced eastwards. Thus, both discrepancies of the wind stress anomaly patterns in the coupled models with respect to observations (narrow meridional extent, and westward displacement along the equator) may be responsible for the ENSO timescale being shorter in the models than in observations. The examination of the leading advective processes in the SST tendency equation indicates that vertical advection of temperature anomalies tends to favor ENSO growth in all the CGCMs, but at a smaller rate than in observations. In some models it can also promote a phase transition. Longer periods tend to be associated with thermocline and advective feedbacks that are in phase with the SST anomalies, while advective tendencies that lead the SST anomalies by a quarter cycle favor ENSO transitions, thus leading to a shorter period.

A foraminiferal investigation documents the palaeoenvironmental changes across the sapropel units associated with insolation—cycles 90 and 86 in the Early–Middle Pleistocene IM/Fosso 5 Agosto section (Basilicata, southern Italy). Three benthic foraminiferal fossil associations (Associations A, B and C), identified by performing Hierarchical Cluster Analysis on the quantitative data, can be considered diagnostic of the palaeoenvironmental conditions before, during and after the sapropel intervals. They indicate a gradual decrease of bottom water oxygenation prior to the onset of sapropel deposition and a rapid return to stable environmental conditions at the end of the sapropel events. The constant presence of benthic foraminifera throughout the sapropels implies that the bottom environment was not totally anoxic. The high-resolution distributional pattern of planktonic and benthic foraminifera within the sapropel associated with i-cycle 90 documents a surface water cooling with consequent rapid re-oxygenation of bottom waters that subdivides this interval in two phases. Both of them are characterized by an early subphase with warm climate conditions, a decrease of salinity in surficial water layers and dominated by the low oxygen tolerant benthic species Globobulimina affinis. The late subphase shows thermal stratification during summer and a relatively deep and oxygenated mixed layer during winter. In this subphase, the contemporaneous replacement of G. affinis, the bless opportunistic, but more resistant to low oxygen conditionsQ species with Bolivina alata, Bolivina dilatata and Brizalina spathulata, the bless resistant to low oxygen conditionsQ species, indicates the relative oxygen improvement in sediment pore water. The frequent changes detected in the sapropel-associated faunal composition underline the unstable nature of bottom water oxygen content. D 2004 Elsevier B.V. All rights reserved.

The island of Elba has been known since antiquity as the major source of metals, especially iron, for the Etruscan civilisation. Unfortunately, the archaeometallurgic record of the island has been destroyed during our century so the present knowledge of this history is very poor and only historical sources constrain the timing. We present in this article indirect evidence of this activity buried in the sea deep that will shed new light on the archaeometallurgic history of the Western Mediterranean. Magnetic properties of marine sediments collected in the Corsica Channel imply enrichment in ferrimagnetic minerals and trace metals related to anthropic impact. Accelerator mass spectrometry 14C ages suggest that the contamination started about 4000 years ago; we attribute it to emissions of fly-ash from the Etruscan smelting technologies for metal production. These results show that archaeometallurgic activity started on Elba Island in the II Millennium BC, much earlier than previously assumed.

Core M 25/4-12, a long piston core (12.20 m) recovered in the Ionian Sea during cruise M25/4 of the R/V Meteor (summer 1993) at a water depth of 2467 m, shows an almost complete sequence of sapropels (S-1, S-3 to S-10) over the last 330 ka. This paper presents the results of an integrated study based on quantitative biostratigraphic analyses, performed on both calcareous nannofossils and planktonic foraminifera, coupled with the δ18O record. A decrease in Syracosphaera? sp. 1 and an increase in the abundance of the genus Rhabdosphaera and of Helicosphaera carteri, Florisphaera profunda and of the reworked specimens, has been found in the calcareous nannofossil assemblage within the sapropels. The planktonic foraminiferal assemblage of the sapropels is characterized by a peak in the frequency of Globigerinoides ruber (var. alba and rosea) and Neogloboquadrina dutertrei. The δ18O record of Globigerinoides ruber and Globigerina bulloides allows recognition of isotope stages 1 to 9 and shows a negative fluctuation that corresponds to the sapropel layers. These features support the idea of increased productivity coupled to the presence of reduced salinity surface waters that caused the deposition of the sapropels. However, the need for a good understanding of the ecological requirements of modern assemblages is stressed. This is necessary to correctly interpret fossil assemblages. This in turn will allow a better understanding of the palaeoceanographic conditions leading to sapropel deposition.

The planktic foraminiferal distribution identified in 60 cores collected in different basins of the Mediterranean Sea allowed to establish an ecostratigraphical scheme which provides a very important tool for the biochronological subdivision of the uppermost Quaternary. We identified a succession of ten ecozones during the last 23 ka in the Tyrrhenian basin and eight ecozones in the Adriatic Sea during the last 15 ka. The ecozones boundaries have been calibrated by 14C AMS radiometric data and by the stable oxygen isotope record. The chronological framework defined by the successive bioevents shows a very high resolution (millenary scale) and evidences that the changes in the planktic microfauna occurred more or less synchronously throughout the central Mediterranean Sea. Differences due to different oceanographic settings of the basins do not affect the general distributional pattern of planktic foraminifera.