196,495 research outputs found
Diagnostic and management strategies of aspergillus endophthalmitis: current insights
No full textFungal endophthalmitis is subsequent to endogenous or exogenous infection and represents an important complication of ocular surgery which may lead to significant visual loss and blindness. The prognosis is poor because of delayed diagnosis and limited availability of effective antifungal drugs with good ocular penetration. Furthermore, the critical issue in diagnosing fungal infection of the eye is microbiological identification of the etiologic agent in clinical samples. Aspergillus is among the most frequent isolated organisms in fungal endophthalmitis. Early diagnosis is essential to prevent severe complications and blindness. Treatments include local, systemic and surgical therapeutic strategies. The purpose of the present review is the analysis of the current procedures adopted to promptly diagnose and treat Aspergillus endophthalmitis
Source characteristics of the basement rocks from the Sulu and Celebes Basins (Western Pacific): Chemical and isotopic evidence
No full textNew Sr- Nd- and Pb-isotopic and trace element data are presented on basalts from the Sulu and Celebes Basins, and the submerged Cagayan Ridge Arc (Western Pacific), recently sampled during Ocean Drilling Program Leg 124. Drilling has shown that the Sulu Basin developed about 18 Ma ago as a backarc basin, associated with the now submerged Cagayan Ridge Arc, whereas the Celebes Basin was generated about 43 Ma ago, contemporaneous with a general plate reorganisation in the Western Pacific, subsequently developing as an open ocean receiving pelagic sediments until the middle Miocene. In both basins, a late middle Miocene collision phase and the onset of volcanic activity on adjacent arcs in the late Miocene are recorded. Covariations between 87Sr/86Sr and 143Nd/144Nd show that the seafloor basalts from both the Sulu and Celebes Basins are isotopically similar to depleted Indian mid-ocean ridge basalts (MORB), and distinct from East Pacific Rise MORB, defining a single negative correlation. The Cagayan Arc volcanics are different, in that they have distinctly lower ɛNd(T) for a given ɛSr(T), compared to Sulu and Celebes basalts. In the 207Pb/204Pb and 208Pb/204Pb versus 206Pb/204Pb diagrams, the Celebes, Sulu and Cagayan rocks all plot distinctly above the Northern Hemisphere Reference Line, with high Δ7/4 Pb (5.3–9.3) and D8/4 Pb (46.3–68.1) values. They define a single trend of radiogenic lead enrichment from Celebes through Sulu to Cagayan Ridge, within the Indian Ocean MORB data field. The data suggest that the overall chemical and isotopic features of the Sulu, Cagayan and Celebes rocks may be explained by partial melting of a depleted asthenospheric N-MORB-type (“normal”) mantle source with isotopic characteristics similar to those of the Indian Ocean MORB source. This asthenospheric source was slightly heterogeneous, giving rise to the Sr-Nd isotopic differences between the Celebes and Sulu basalts, and the Cagayan Ridge volcanics. In addition, a probably slab-derived component enriched in LILE and LREE is required to generate the elemental characteristics and low Nd(T) of the Cagayan Ridge island arc tholeiitic and calcalkaline lavas, and to contribute to a small extent in the backarc basalts of the Sulu Sea. The results of this study confirm and extend the widespread Indian Ocean MORB signature in the Western Pacific region. This signature could have been inherited by the Indian Ocean mantle itself during the rupture of Gondwanaland, when fragments of this mantle could have migrated towards the present position of the Celebes, Sulu and Cagayan sources
Beam-Column connection for FRP structures
No full textThe use of FRP profiles is appropriate and advantageous for construction of industrial and low-rise residential buildings as well as temporary structures built in emergency situations. But for FRP composite structures to be competitive with structures made of traditional materials, they must be safe, serviceable, durable and economical. Structural safety and serviceability depend on the structural members’, as well as on their joints’ or connections’, strength and stiffness. Currently, the connections in FRP structures are commonly made using bolted connections [1-2], akin to those used in steel structures while, as stipulated in a recent European guideline [3], bonded connections are not allowed for primary load bearing components.
Figure 1. a) Connection tested in [4], b) new connection.
With respect to bonded beam-to-column moment resisting connections, the authors in a recent paper [4] demonstrated that this prohibition appears to be unjustified. An identical pultruded GFRP I-profile was used to form the beam and the column elements. The two elements were connected by epoxy adhesive, and GFRP seat angles, bonded to the column compression flange and the beam tension and compression flanges. In addition, stiffeners were used in the connection region to strengthen the column flange and web. The beam, acting as a cantilever, was loaded by a point load near its free end, which subjected the connection to combined bending and shear. The connection (Figure 1a) failed by debonding within the adhesive, achieving nearly the same percentage of the GFRP profile ultimate moment capacity as in the best performing bolted connections tested by others.
As a follow up to the previous work, in order to further enhance the forgoing connection strength and stiffness, in this study the column and the seating angle bonded to the beam tension face and the column are strapped together using a carbon wrap as depicted in Figure 2b. The new connection is loaded identically to the previously tested connection, and, compared to the companion unwrapped connection, the results of the improved connection show increase in both the ultimate moment resistance and rotational stiffness. This improvement makes adhesive connections an even more appealing choice for practical applications.
[1] L.C. Bank, A.S. Mosallam, G.T. McCoy, Journal of Reinforced Plastics and Composites, 15, 1052 (1994).
[2] S.J. Smith, I.D. Parsons, K.D. Hjelmstad, Journal of Composite for Construction, 3, 20 (1999).
[3] Report EUR 27666 EN, Prospect for new guidance in the design of FRP. JRC Science for Policy Report, 2016.
[4] F. Ascione, M. Lamberti, A.G. Razaqpur, S. Spadea, S., J. Comp. Struct., 160, 1248 (2017)
A Story-telling approach to the introduction of the multiplicative structure at kindergarten
No full textWe present a design study based on a story-telling approach,
to introduce multiplicative thinking at Kindergarten with an algebraic
perspective. Starting from some theoretical assumptions about the use
of narration in Math Education and about the psychological roots of
multiplication, we build a suitable narrative context in order to promote
children’s actions consistent with such roots.We analyse the development
of this path and its management, emphasizing the special role played by
the dialectics between actions upon objects and representations
Pedestrian bridge as clarifying example of FRP-RC/PC design
No full textEmployment of corrosion-resistant reinforcement represents a widely-recognized effective strategy to ensure long-term durability of reinforced concrete (RC) and prestressed concrete (PC) structures. Fiber-reinforced polymer (FRP) composites have proved to be a reliable non-metallic solution, able to ensure both the required mechanical performance and corrosion resistance. FRP-RC infrastructural applications are currently spreading; conversely, FRP-PC bridges are still considered state of the art prototypes. Many are the conceptual and practical challenges accompanying this innovative technology: brittleness of FRP reinforcement, likelihood of tensioncontrolled failure, limitations on the initial pull force, limitations on the sustained load that the member can carry, and service requirements that may control the design. Reports published by ACI committee 440 do not yet address FRP-RC/PC provisions in a consistent way. Discrepancies exist on how ACI 440.1R and ACI 440.4R approach FRP-RC/PC design, having the latter not being updated since the first generation of FRP regulations. This paper deals with the philosophy behind the design of the precast Carbon FRP-PC/Basalt FRP-RC double-tee girders and the auxiliary Basalt FRP-RC/Glass FRP-RC members that constitute the structure of a recently built pedestrian bridge. This study is an attempt to address the challenges still preventing the wide acceptance of CFRP in prestress applications and to unify the design approach for FRP-RC/PC structures. This successful case-study validates the proposed rationale and supports a slight relaxation of the design limits in terms of initial pull force
Source characteristics of the basement rocks from the Sulu and Celebes Basins (Western Pacific): chemical and isotopic evidence
No full textIl monumento della Pace di Piazza Libertà di Udine: materiali, tecniche e risultati del restauro
No full textDesign analysis and experimental behavior of precast concrete double-tee girders prestressed with carbon-fiber-reinforced polymer strands
No full textPost-operative endophthalmitis caused by Acremonium falciforme with orbital and extra-orbital involvement following combined cataract and glaucoma surgery: a case report.
No full textIntroduction: In this report, we describe an unusual case of post-operative Acremonium falciforme endophthalmitis with orbital and extra-orbital involvement following combined cataract and glaucoma surgery. Case presentation: A 68-year-old Caucasian man with glaucoma presented with endophthalmitis characterized by pain, redness and impaired vision in the left eye fifteen days after combined cataract and filtering surgery. He subsequently underwent a pars plana vitrectomy, with vitreous sampling, silicone oil placement and intra-vitreal injection of antibiotics, but only after a second vitrectomy we identified Acremonium falciforme as the causative agent for the endophthalmitis. An antifungal systemic and topical therapy was started, but meanwhile the infection extended to orbital and peri-orbital tissues. Following these procedures, even if the eye went slowly in phthisis, we were able to limit the further extension and circumscribe the orbital and extra-orbital involvement. Conclusion: To our knowledge, this report is the first describe Acremonium falciforme endophthalmitis with orbital and extra-orbital involvement, following anterior segment combined surgery. Ophthalmologists and physicians should be aware of the extension risk of a fungal panophthalmitis, but also to potentially serious side effects related to systemic therapy. © 2014 Cagini et al.; licensee BioMed Central Ltd
A crack growth strategy based on moving mesh method and fracture mechanics
No full textA numerical model based on moving mesh strategy is proposed to simulate the evolution of internal material discontinuities in a continuum medium. The approach combines concepts arising from structural mechanics and moving mesh methodology, which are implemented in a unified framework to predict crack growth on the basis of Fracture Mechanics variables. In particular, moving computational nodes are modified starting from a fixed referential coordinate system on the basis of a crack growth criterion to predict directionality and displacement of the tip front. The use of rezoning mesh methods coupled with a proper advancing crack growth scheme ensures the consistency of mesh motion with small distortions and an unaltered mesh typology. In addition, the moving grid is modified from the initial configuration in such a way that the recourse to re-meshing procedures is strongly reduced. The numerical formulation and its computational implementation show how the proposed approach can be easily embedded in classical finite element software. Finally, numerical examples in the presence of internal material discontinuities and comparisons with existing data obtained by advanced numerical approaches and experimental data are proposed to check the validity of the formulation.</p
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