Tpa (Poland)

Drilled displacement columns, constructed in the form of unreinforced or reinforced concrete elements, are currently a very commonly used method of improving soft subsoil, creating an alternative to more expensive pile foundations. A frequently used solution for improving soft soils of road or railway embankments is to design a regular pattern of columns of relatively small diameter. Columns along the perimeter of the improved area are reinforced with rigid steel profiles, while the internal ones are made as concrete elements. Column heads are usually covered with a load transfer platform (layer of compacted granular fill) which is additionally reinforced with geosynthetics. The application of soil improvement with displacement columns is not always successful. It is due to the errors and shortcomings occurring at the design stage, including simplifications in modelling, to construction faults, which may include insufficient experience of contractors and/or improper supervision. Referring to the real object that failed, the article provides the results of numerical parametric analyses taking into account the influence of the key design parameters such as: the stiffness of the load transfer layers, the amount and stiffness of the geosynthetic reinforcement as well as the column spacing. The article presents comparisons of numerical results obtained with the finite element analyses for various approaches to geometry modelling (axisymmetric, 2D and 3D). The simulations indicate that the use of the axisymmetric model of a single column in routine design may lead to the deformations exceeding the serviceability limit states.

Designing retaining structures depends on many factors, primarily the function of the retaining structure and soil conditions. It is not easy to choose the right retaining structure due to the great variety of their structural and material solutions. Preliminary numerical analyses in this case can be very useful. This article presents the results of numerical analyses of the behaviour of retaining structures and soil for various structural and material solutions as well as defined soil and water conditions. Six variants of retaining structures were analysed, in which the type of retaining walls, the materials used and the height of the walls were varied. The assessment was done basing on maps of stress and displacement of the retaining structure and soil. An additional factor in the selection of retaining structures are costs, durability and lead time. The finite element method allows the analysis of the behaviour of the structure - soil system. It enables comparison of various construction variants at the design stage and selection of the best solution in given soil and water conditions for the set selection criteria.

High levels of plasma lipids have been recognized as a major risk factor in the development and progression of atherosclerosis, and to influence hemorheological factors that may predispose to thrombotic complications. Lipid-lowering interventions have been associated with a significant reduction of morbidity and mortality. Several mechanisms have been postulated for the observed clinical effect. Serum lipid-regulating therapies may reduce cardiovascular risk not only by altering the arterial wall, improving disturbed endothelial function, atherogenesis and plaque stability, but also through their antithrombogenic effects and influence on blood flow properties associated with hyperlipidemia. In this article, we will review the recent literature and discuss the value of hemorheological-hemostatic findings as surrogate endpoints for clinical trials in dyslipidemic patients.

Advances in stroke therapy have followed diverse paths over the past 2 years. Recent clinical trials have investigated the use of thrombolytic agents, anticoagulants, antiplatelet drugs and neuroprotective agents in acute stroke patients. The positive results of the National Institutes of Neurologic Disease and Stroke tissue plasminogen activator trial have increased interest in the field of acute stroke therapy and initiated significant changes in the management of stroke patients in the medical system. A new antiplatelet drug and a number of trials involving HMG Co-A reductase inhibitors are important advances in the secondary prevention of stroke.

Although cataract surgery for senile cataract is routine and easily performed, the decision to remove the cataract in a patient with a history of uveitis is considerably more complex and usually involves multiple considerations, related not only to the cause of the uveitis but also to the appropriate surgical procedures. The problems confronting the ophthalmologist caring for the patient with uveitis begin with the first visit. Establishing a diagnosis and controlling the inflammation are the critical elements in the treatment of the patient; these two factors will determine the incidence of cataract formation and other complications, the appropriate time for cataract removal, and the surgical strategy, as well as determine the visual outcome long before surgery occurs. Diagnosis, control of inflammation, preoperative management, particularities of the surgical techniques, and postoperative complications in patients with a history of uveitis have been reviewed previously in this section. Our aims in this article are to review the literature on this subject over the past year and to reemphasize the idea of a model of zero tolerance for inflammation to minimize the incidence of cataract and irreversible damage of ocular structures essential to good vision.