2,076 research outputs found

    Lower pliocene barnacle facies of western liguria (NW Italy): A peek into a warm past and a glimpse of our incoming future

    Get PDF
    The lower Pliocene deposits of Pairola (Liguria, Italy) display the otherwise rare occurrence of rock-forming amounts of barnacles (mostly belonging to the extinct Euromediterranean species Concavus concavus). Three main facies are recognised in the investigated succession: a barnacle-dominated facies, which formed along a shallow (<15 m deep) nearshore environment, a foraminifera-dominated facies from relatively deeper waters (40-100 m), and an intermediate facies forming at the boundary of the other two. These facies and their relationships suggest deposition in a flooded valley – a kind of setting that was common in the Mediterranean after the Messinian Salinity Crisis. Differing from other rias, the Pairola basin was exposed to strong waves, resulting in conditions favourable to barnacles. Sedimentological and stratigraphic observations indicate that the Pairola succession formed within a timespan covering both cold and warm phases. This is relevant because the sub-tropical foraminifer Amphistegina is ubiquitous throughout the succession. Amphistegina occurs in the Pliocene and lower Pleistocene (Gelasian) of Northern Italy, but not in the remainder of the Pleistocene, not even its warm portions. This genus is currently recolonizing the Mediterranean and is projected to reach the northern coast of the basin soon, foretelling that Anthropocene temperatures are going to overcome those of the late Pleistocene warm periods and reach those of the Pliocene

    Lateral cephalometric analysis of asymptomatic volunteers and symptomatic patients with and without bilateral temporomandibular joint disk displacement

    Get PDF
    Few studies of dentofacial and orthodontic structural relationships relative to temporomandibular joint (TMJ) dysfunction have been reported. We undertook this investigation to determine any correlation of orthodontic and dentofacial characteristics with TMJ bilateral disc displacement. The population of patients was selected from a TMJ clinic where a control group of asymptomatic volunteers had been previously established and standardized. Differences in skeletal structural features were determined among three study groups: (1) asymptomatic volunteers with no TMJ disk displacement, (2) symptomatic patients with no TMJ disc displacement, and (3) symptomatic patients with bilateral TMJ disk displacement. Thirty-two asymptomatic volunteers without disk displacement (25 female, 7 male) were compared with the same number each of symptomatic patients without TMJ disk displacement and symptomatic patients with bilateral TMJ disk displacement. All subjects had undergone a standardized clinical examination, bilateral TMJ magnetic resonance imaging, and lateral cephalometric radiographic analysis. The groups were matched according to sex, TMJ status, age, and Angle classification of malocclusion. Seventeen lateral cephalometric radiographic cranial base, maxillomandibular, and vertical dimension variables were evaluated and compared among the study groups. The mean angle of SNB, or the intersection of the sella-nasion plane and the nasion–point B line (indicating mandibular retrognathism relative to cranial base), of the symptomatic patients-with-displacement group was significantly smaller than that in the asymptomatic volunteers and symptomatic patients without bilateral disk displacement (p \u3c 0.05). Female subjects showed smaller linear measurements of mandibular length, lower facial height, and total anterior facial height than male subjects in all three groups (p \u3c 0.05). The mean angle of ANB, or the intersection of the nasion–point A and nasion–point B planes (indicating retrognathism of mandible relative to maxilla), was significantly greater in female than in male subjects, in all groups (p \u3c 0.05). Symptomatic patients with bilateral disk displacement had a retropositioned mandible, indicated by a smaller mean SNB angle compared with that in asymptomatic volunteers and symptomatic patients with no disk displacement on either side. Lateral cephalometric radiographic assessment may improve predictability of TMJ disk displacement in orthodontic patients but is not diagnostic; nor does the assessment explain any cause-and-effect relationship. (Am J Orthod Dentofacial Orthop 1998;114:248-55.

    Statistical Reliability Estimation of Microprocessor-Based Systems

    Get PDF
    What is the probability that the execution state of a given microprocessor running a given application is correct, in a certain working environment with a given soft-error rate? Trying to answer this question using fault injection can be very expensive and time consuming. This paper proposes the baseline for a new methodology, based on microprocessor error probability profiling, that aims at estimating fault injection results without the need of a typical fault injection setup. The proposed methodology is based on two main ideas: a one-time fault-injection analysis of the microprocessor architecture to characterize the probability of successful execution of each of its instructions in presence of a soft-error, and a static and very fast analysis of the control and data flow of the target software application to compute its probability of success. The presented work goes beyond the dependability evaluation problem; it also has the potential to become the backbone for new tools able to help engineers to choose the best hardware and software architecture to structurally maximize the probability of a correct execution of the target softwar

    A new chelonibiid from the Miocene of Zanzibar (Eastern Africa) sheds light on the evolution of shell architecture in turtle and whale barnacles (Cirripedia: Coronuloidea)

    Get PDF
    The fossil history of turtle and whale barnacles (Coronuloidea: Chelonibiidae, Platylepadidae, Coronulidae and †Emersoniidae) is fragmentary and has only been investigated in part. Morphological inferences and molecular phylogenetic analyses on extant specimens suggest that the roots of whale barnacles (Coronulidae) are to be found among the chelonibiid turtle barnacles, but the hard-part modifications that enabled early coronuloids to attach to the cetacean skin are still largely to be perceived. Here, we reappraise a fossil chelonibiid specimen from the Miocene of insular Tanzania that was previously referred to the living species Chelonibia caretta. This largely forgotten specimen is here described as the holotype of the new species †Chelonibia zanzibarensis. While similar to C. caretta, †C. zanzibarensis exhibits obvious external longitudinal parietal canals occurring in-between external longitudinal parietal septa that abut outwards to form T-shaped flanges, a character so far regarded as proper of the seemingly more derived Coronulidae and Platylepadidae. Along with these features, the presence of a substrate imprint on the shell exterior indicates that †C. zanzibarensis grasped its host's integument in much the same way as coronulids and platylepadids, albeit without the development of macroscopic parietal buttresses and bolsters. Thin section analyses of the inner parietal architecture of some extant and extinct coronuloids conclusively demonstrate that vestiges of comparable external parietal microstructures are present in some living members of Chelonibiidae. This observation strengthens the unity of Coronuloidea while significantly contributing to our understanding of the evolution of the coronuloid shell structure in adapting to a diverse spectrum of hosts

    Circuit training during physical education classes to prepare cadets for military academies tests: Analysis of an educational project

    Get PDF
    Background: The aim of this study was to test the efficacy of an eight-week physical education program based on circuit training to better improve the overall physical and military-specific performance compared to a conventional physical education program in military high school students. Methods: Sixty-four students were enrolled in this study and randomly assigned to an experimental (EG, circuit training) or a control group (CG, traditional physical education program). Immediately before and after the eight-week training period, participants were tested on strength and endurance performance, circuit training tests, and military tests. Moreover, the acquisition of the educational objectives and the pleasantness of the experimental intervention were tested using a qualitative approach. Results: Despite the higher workload in EG than CG during the training period, the effect of the experimental intervention compared to the control was only possibly to likely positive for a few strength and endurance performances and circuit training tests, respectively. A trivial effect was shown in the military tests. On the contrary, the high percentage of motivation (76%), understanding (78%) and collaboration (86%) showed by the students suggests the achievement of acquisition of the educational objectives and a fair pleasantness of the lessons. Conclusions: A lack of clear and marked effect of the experimental intervention could be ascribed to an insufficient exposure time to the training and a high subjective overall workload encountered in military high school students

    Palaeoenvironmental analysis of the Miocene barnacle facies: case studies from Europe and South America

    Get PDF
    Acorn barnacles are sessile crustaceans common in shallow-water settings, both in modern oceans and in the Miocene geological record. Barnacle-rich facies occur from polar to equatorial latitudes, generally associated with shallow-water, high-energy, hard substrates. The aim of this work is to investigate this type of facies by analysing, from the palaeontological, sedimentological and petrographical points of view, early Miocene examples from Northern Italy, Southern France and South-western Peru. Our results are then compared with the existing information on both modern and fossil barnacle-rich deposits. The studied facies can be divided into two groups. The first one consists of very shallow, nearshore assemblages where barnacles are associated with an abundant hard-substrate biota (e.g., barnamol). The second one includes a barnacle-coralline algae association, here named “barnalgal” (= barnacle / red algal dominated), related to a deeper setting. The same pattern occurs in the distribution of both fossil and recent barnacle facies. The majority of them are related to very shallow, high-energy, hard-substrate, a setting that represents the environmental optimum for the development of barnacle facies, but exceptions do occur. These atypical facies can be identified through a complete analysis of both the skeletal assemblage and the barnacle association, showing that barnacle palaeontology can be a powerful tool for palaeoenvironmental reconstruction

    Synthesis of easily sinterable ceramic electrolytes based on Bi-doped 8YSZ for IT-SOFC applications

    Get PDF
    Ceramic electrolytes formed by Bi (4 mol%)-doped 8YSZ, i.e., Y2O3 (8 mol%)-doped ZrO2, were synthesized by a simple co-precipitation route, using ammonia solution as precipitating agent. The amorphous as-synthesized powders convert into zirconia-based single phase with fluorite structure through a mild calcination step at 500 \ub0C. The calcined powders were sintered at very low temperatures (i.e., 900-1100 \ub0C) achieving in both cases very high values of relative densities (i.e., > 95%); the corresponding microstructures were highly homogeneous and characterized by micrometric grains or sub-micrometric grains for sintering at 1100 \ub0C and 900 \ub0C, respectively. Very interesting electrochemical properties were determined by Electrochemical Impedance Spectroscopy (EIS) in the best samples. In particular, their total ionic conductivity, recorded at 650 \ub0C, are 6.06 7 10-2S/cm and 4.44 7 10-2S/cm for Bi (4 mol%)-doped 8YSZ sintered at 1100 \ub0C and 900 \ub0C, respectively. Therefore, Bi was proved to be an excellent sintering aid dopant for YSZ, highly improving its densification at lower temperatures while increasing its total ionic conductivity

    Surface Induced Order in Liquid Metals and Binary Alloys

    Full text link
    Measurements of the surface x-ray scattering from several pure liquid metals (Hg, Ga, and In) and from three alloys (Ga-Bi, Bi-In, and K-Na) with different heteroatomic chemical interactions in the bulk phase are reviewed. Surface-induced layering is found for each elemental liquid metal. The surface structure of the K-Na alloy resembles that of an elemental liquid metal. Bi-In displays pair formation at the surface. Surface segregation and a wetting film are found for Ga-Bi.Comment: 10 pages, 3 fig, published in Journal of Physics: Condensed Matte
    • 

    corecore