On soil-structure interaction in large non-slender partially buried structures

This paper addresses the seismic analysis of a deeply embedded non-slender structure hosting the pumping unit of a reservoir. The dynamic response in this type of problems is usually studied under the assumption of a perfectly rigid structure using a sub-structuring procedure (three-step solution) proposed specifically for this hypothesis. Such an approach enables a relatively simple assessment of the importance of some key factors influencing the structural response. In this work, the problem is also solved in a single step using a direct approach in which the structure and surrounding soil are modelled as a coupled system with its actual geometry and flexibility. Results indicate that, quite surprisingly, there are significant differences among prediction using both methods. Furthermore, neglecting the flexibility of the structure leads to a significant underestimation of the spectral accelerations at certain points of the structure

Dynamic Winkler Modulus for Axially Loaded End-Bearing Piles

The problem of dynamic pile-soil interaction and its modeling through the concept of a Dynamic Winkler Foundation are revisited. It is shown that depth-dependent Winkler springs and dashpots, obtained by dividing the complex-valued soil shear tractions and the corresponding displacements along the pile, may faithfully describe pile-soil interaction, contrary to common perception that the Winkler model is always approximate. A theoretical wave model is then derived for analyzing the response of axially loaded endbearing piles embedded in a homogeneous viscoelastic soil medium. Closed-form solutions are obtained for: (i) the displacement field in the soil and along the pile; (ii) the impedance coefficients (stiffness and damping) at the pile head; (iii) the depth-dependent Winkler moduli along the pile; (iv) the average, depth-independent, Winkler moduli to match the impedance coefficient at the pile head. Results are presented in terms of dimensionless graphs and charts that highlight the salient features of the problem. The predictions of the model compare favorably with established solutions from the literature, while new results are presented

Acute febrile illness is associated with Rickettsia spp infection in dogs

BACKGROUND: Rickettsia conorii is transmitted by Rhipicephalus sanguineus ticks and causes Mediterranean Spotted Fever (MSF) in humans. Although dogs are considered the natural host of the vector, the clinical and epidemiological significance of R. conorii infection in dogs remains unclear. The aim of this prospective study was to investigate whether Rickettsia infection causes febrile illness in dogs living in areas endemic for human MSF. METHODS: Dogs from southern Italy with acute fever (n = 99) were compared with case–control dogs with normal body temperatures (n = 72). Serology and real-time PCR were performed for Rickettsia spp., Ehrlichia canis, Anaplasma phagocytophilum/A. platys and Leishmania infantum. Conventional PCR was performed for Babesia spp. and Hepatozoon spp. Acute and convalescent antibodies to R. conorii, E. canis and A. phagocytophilum were determined. RESULTS: The seroprevalence rates at first visit for R. conorii, E. canis, A. phagocytophilum and L. infantum were 44.8%, 48.5%, 37.8% and 17.6%, respectively. The seroconversion rates for R. conorii, E. canis and A. phagocytophilum were 20.7%, 14.3% and 8.8%, respectively. The molecular positive rates at first visit for Rickettsia spp., E. canis, A. phagocytophilum, A. platys, L. infantum, Babesia spp. and Hepatozoon spp. were 1.8%, 4.1%, 0%, 2.3%, 11.1%, 2.3% and 0.6%, respectively. Positive PCR for E. canis (7%), Rickettsia spp. (3%), Babesia spp. (4.0%) and Hepatozoon spp. (1.0%) were found only in febrile dogs. The DNA sequences obtained from Rickettsia and Babesia PCRs positive samples were 100% identical to the R. conorii and Babesia vogeli sequences in GenBank®, respectively. Febrile illness was statistically associated with acute and convalescent positive R. conorii antibodies, seroconversion to R. conorii, E. canis positive PCR, and positivity to any tick pathogen PCRs. Fourteen febrile dogs (31.8%) were diagnosed with Rickettsia spp. infection based on seroconversion and/or PCR while only six afebrile dogs (12.5%) seroconverted (P = 0.0248). The most common clinical findings of dogs with Rickettsia infection diagnosed by seroconversion and/or PCR were fever, myalgia, lameness, elevation of C-reactive protein, thrombocytopenia and hypoalbuminemia. CONCLUSIONS: This study demonstrates acute febrile illness associated with Rickettsia infection in dogs living in endemic areas of human MSF based on seroconversion alone or in combination with PCR

Placental syncytiotrophoblast constitutes a major barrier to vertical transmission of Listeria monocytogenes.

Listeria monocytogenes is an important cause of maternal-fetal infections and serves as a model organism to study these important but poorly understood events. L. monocytogenes can infect non-phagocytic cells by two means: direct invasion and cell-to-cell spread. The relative contribution of each method to placental infection is controversial, as is the anatomical site of invasion. Here, we report for the first time the use of first trimester placental organ cultures to quantitatively analyze L. monocytogenes infection of the human placenta. Contrary to previous reports, we found that the syncytiotrophoblast, which constitutes most of the placental surface and is bathed in maternal blood, was highly resistant to L. monocytogenes infection by either internalin-mediated invasion or cell-to-cell spread. Instead, extravillous cytotrophoblasts-which anchor the placenta in the decidua (uterine lining) and abundantly express E-cadherin-served as the primary portal of entry for L. monocytogenes from both extracellular and intracellular compartments. Subsequent bacterial dissemination to the villous stroma, where fetal capillaries are found, was hampered by further cellular and histological barriers. Our study suggests the placenta has evolved multiple mechanisms to resist pathogen infection, especially from maternal blood. These findings provide a novel explanation why almost all placental pathogens have intracellular life cycles: they may need maternal cells to reach the decidua and infect the placenta

A simple method for N-M interaction diagrams of circular reinforced concrete cross sections

A novel analytical method is derived for the ultimate capacity interaction diagram (i.e., axial compression, N - bending moment resistance, M) of reinforced concrete (RC) columns with circular cross section. To this aim, the longitudinal rebar arrangement is replaced with a thin steel ring equivalent to the total steel area; moreover, according to modern design approaches, simplified stress–strain relationships for concrete and reinforcing steel are used. Illustrative applications demonstrate that the ultimate capacity computed by the proposed analytical approach agrees well with the results obtained by rigorous methods based on consolidated numerical algorithms. The new solution allows for a rapid, accurate assessment of circular cross section capacity by means of hand calculations; this is especially useful at the conceptual design stage of various structural and geotechnical systems. The method can be easily extended to more general configurations, such as multiple steel rings and composite concrete-steel sections

Practical bone marrow cytology in the dog and cat

Η κυτταρολογική εξέταση του μυελού των οστών (ΜΟ) αποτελεί ένα πρακτικό διαγνωστικό εργαλείο στην ιατρική του σκύλου και της γάτας, που επιτρέπει τη λεπτομερή μορφολογική εκτίμηση κυττάρων και μικροοργανισμών. Οι κυριότερες ενδείξεις για την κυτταρολογική εξέταση του ΜΟ περιλαμβάνουν τη διερεύνηση ασυνήθιστων κλινικών (π.χ. πυρετός, απώλεια σωματικού βάρους), αιματολογικών (π.χ. αναιμία, λευκοκυττάρωση) και βιοχημικών διαταραχών, τη διάγνωση και την κλινική σταδιοποίηση νεοπλασμάτων (π.χ. λέμφωμα, μαστοκύττωμα), τη διάγνωση σημαντικών λοιμωδών νοσημάτων όπως της λεϊσμανίωσης (Leishmania infantum) και της μονοκυτταρικής ερλιχίωσης (Ehrlichia canis) του σκύλου, καθώς και την εκτίμηση της παρακαταθήκης σιδήρου στο ΜΟ του σκύλου. Η παρακέντηση του ΜΟ είναι πολύ ασφαλής και ο απαιτούμενος εξοπλισμός ελάχιστα δαπανηρός, γεγονός που εξηγεί τη μεγαλύτερη συχνότητα με την οποία διενεργείται στην κλινική πράξη σε σχέση με την οστεομυελική βιοψία. Στην ανασκόπηση αυτή περιγράφονται οι τεχνικές λεπτομέρειες για την αξιόπιστη συλλογή ΜΟ και κυρίως τα συνήθη ανατομικά σημεία για τη δειγματοληψία, ο απαιτούμενος εξοπλισμός, η προετοιμασία του ζώου, η τεχνική αναρρόφησης του ΜΟ και η διαδικασία παρασκευής κυτταρολογικών επιχρισμάτων. Ιδιαίτερη έμφαση δίνεται στην περιγραφή του φυσιολογικού κυτταρικού πληθυσμού του ΜΟ στο σκύλο και στη γάτα, καθώς και στην οργανωμένη εξέταση και ερμηνεία των κυτταρολογικών ευρημάτων. Τέλος, παρουσιάζεται επιγραμματικά η σύγχρονη κυτταρολογική διάκριση των νεοπλασμάτων του ΜΟ στο σκύλο και στη γάτα.In companion animal medicine, bone marrow (BM) aspiration cytology is a cost-effective diagnostic tool, which provides excellent morphological detail of cells and infectious agents. The major indications for BM aspiration include unexplained clinical manifestations (e.g., fever, body weight loss), persistent hematological or biochemical abnormalities (e.g., anemia, leukocytosis), diagnosis and/or staging of malignancies (e.g., lymphoma, mast-cell tumor), diagnosis of important infectious diseases such as leishmaniosis (Leishmania infantum) and canine monocytic ehrlichiosis (Ehrlichia canis) and evaluation of canine iron stores. Complications associated with BM aspiration are rare and the equipment and supplies required minimal, hence accounting for the popularity of this procedure in the clinical setting compared to BM core biopsy. This review focuses on the technical details pertaining to the collection of BM aspirate material, including the usual anatomic sites for sampling, the equipment required, the preparation of the animal, the aspiration technique and the BM material processing for good quality slide preparation. The description of the cellular population normally anticipated in the BM of the dog and cat and the systematic approach in evaluating and interpreting the BM cytological findings are also highlighted. In the last part of this review, the current classification guidelines for the canine and feline BM malignancies are briefly outlined

Stability Analysis of a 70m-High Cut at an Ancient Landslide Area in Patras, Greece

A 70m-high slope is currently under construction near the entrance of a cut-and-cover tunnel in the inner loop highway of City of Patras – a seismically active area in Western Greece (PGA = 0.24g). The slope consists of marl layers dipping inwards and exhibiting distinct sets of joints. The landscape provides evidence that the site has been subjected to a major landslide at an unknown time in the past. Geotechnical investigation detected a sheared zone at about 15m below ground surface, and a water table a few meters below the planned toe of the slope. The angle and position of the slope surface together with the estimated position of the sheared zone provide a chair-like potentially unstable volume with convex plan view. In addition to the general stability problem, surface instabilities due to the aforementioned sets of joints create the potential of smaller wedge-type failures near the surface of the slope. Following a detailed geotechnical investigation, nonlinear stress finite-element analyses considering both gravitational and earthquake loads were performed. The analyses encompassed a number of different assumptions about: (a) depth to water table, (b) soil strength and (c) geometry of slope and soil layer interfaces. Results show that adequate safety can be achieved using a combination of piles and passive anchors. The effects of various factors/assumptions on the safety of the slope are discussed