418 research outputs found

    Nonlinear Site Response During the 7 September 1999 Athens, Greece, Earthquake (M\u3csub\u3eW\u3c/sub\u3e 5.6)

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    The largest available strong-motion recording (PGA=0.35g), least affected by topography, structural response and/or soil-structure interaction, is investigated for possible nonlinear site response during the M, 5.9 Athens earthquake of 7 September 1999. Smoothed horizontal-to-vertical spectral ratios (HVSR) are calculated in subsequent overlapping 3.5-s windows, thus covering a wide range of excitation levels. Mean HVSR curves are computed for a so-called “weak-“ and “strong-“ motion range (mean horizontal ground acceleration in window, MGA\u3c=10.2 cm/s/s and \u3e=20.5 cm/s/s). The two curves have similar shape, with the “strong” curve visibly shifted toward lower frequencies relative to the “weak” one; the dominant site resonance occurs at 4.0 Hz (0.25 s) and 4.7 Hz (0.21 s), respectively. Linear correlation analysis shows that the resonance frequency, f0, and MGA are significantly correlated (t=-0.661). We attribute this behaviour to the degradation of the sediment shear modulus (nonlinearity). Our results, combined with indications that sediment sites in the near-fault area were exposed to ground shaking well above PGA=0.35 g during the earthquake of 7 September 1999, imply that these sites exhibited considerable nonlinear response

    Digital technologies towards resource efficiency in the agrifood sector: Key challenges in developing countries

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    Resource efficiency in the agri-food sector is a global urgent issue considering the urbanisation phenomena, the increased nutritional needs, and the emergence of diversified dietary norms. Despite the ongoing progress in digital technologies that could enable resource-efficient operations in the sector, their effectiveness—even in developed countries—remains debateable mainly due to the limited understanding that further impedes their adoption by farmers. Among others, ease of access, training, and engagement with digital technologies appears to be challenging for most stakeholders, especially during the production (farming) stage. Specifically, in developing countries, that often encounter major natural resources challenges, the diverse socio-cultural background of the farmers hinders the adoption of digital technologies to perform highly automated and efficient agricultural operations for ensuring sustainability output. In this regard, we explore publicly available data sources (i.e., institutional reports, databases) to identify key challenges in adopting digital technologies for efficient resource use from a systems-level perspective. Thereafter, we map the determinant factors using the System Dynamics methodology in order to identify areas of interventions to limit natural resources’ appropriation and support agri-food sustainability.This research has received funding from the BBSRC under Reference No. BB/P027970/1, Project Title: “Transforming India’s Green Revolution by Research and Empowerment for Sustainable food Supplies”

    Current trends in surgical treatment of parapneumonic effusions and empyema thoracis

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    Surgical treatment of complicated parapneumonic effusions and empyema thoracis consists of drainage and obliteration of the pleural space. Two scientific Societies have published guidelines concerning management of empyema thoracis in the near past. American College of Chest Physicians (2000) has defined criteria of high-risk for poor outcome. Parapneumonic effusions which met the criteria of high-risk for poor outcome should undergo at least chest tube drainage, that is however unsuccessful in 25-50% of cases. Intrapleural instillation of fibrinolytics, thoracoscopic drainage and thoracotomy were, according to ACCP experts, accepted modalities of management. According to British Thoracic Society guidelines (2003), surgical treatment should be offered after failure of conservative treatment with antibiotics and chest tube drainage. We have nowadays enough evidence that early thoracoscopic drainage reduces hospitalization, chest tube drainage duration and that is successful initial treatment in 90% of cases. Minimally invasive thoracoscopic drainage can effectively drain loculations, inflammatory intrapleural fluid and gel, obliterate the pleural cavity and achieve strategic position of chest drains. Thoracoscopic drainage is unsuccessful management for organizing empyemas, where decortication is the treatment of choice. Early involvement of thoracic surgeons and early thoracoscopic drainage may effectively change the prognosis and outcome of complicated parapneumonic effusions and empyema thoracis

    Current status of surgical treatment for pectus excavatum deformity

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    Pectus excavatum is the commonest anterior chest wall deformity which is the result of overgrowth and elon­gation of costal cartilages that push the normal sternum in. The deformity has serious pshychologic impact and limits the exercise tolerance of the patient, because of displacement of the heart within the left hemithorax. Repair of pectus excavatum is performed by the classical Ravich technique or the minimally invasive Nuss repair. The Ravich operation consists of resection of the deformed cartilages, bending the sternum in its normal position and maintenance of the sternum in the correct position by using a metal bar or a strong synthetic mesh. The Nuss procedure involves the thoracoscopic placement of a pre-formed curved metal bar behind the sternum which rises the sternum to the desired position. The selection of the technique depends on the age of the patient and the degree and symmetry of the deformity. The Nuss technique is suitable for children between 5 and 15 years old who have flexible chest wall and symmetric deformities, while the Ravich procedure is indicated in young adults and asymmetric forms. Indeed, the Nuss technique still undergoes modifications to become safer and simpler and further it needs expertise and special equipment

    Misregulated E-Cadherin Expression Associated with an Aggressive Brain Tumor Phenotype

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    BACKGROUND: Cadherins are essential components of the adherens junction complexes that mediate cell-cell adhesion and regulate cell motility. During tissue morphogenesis, changes in cadherin expression (known as cadherin switching) are a common mechanism for altering cell fate. Cadherin switching is also common during epithelial tumor progression, where it is thought to promote tumor invasion and metastasis. E-cadherin is the predominant cadherin expressed in epithelial tissues, but its expression is very limited in normal brain. METHODOLOGY/PRINCIPAL FINDINGS: We identified E-cadherin expression in a retrospective series of glioblastomas exhibiting epithelial or pseudoepithelial differentiation. Unlike in epithelial tissues, E-cadherin expression in gliomas correlated with an unfavorable clinical outcome. Western blotting of two panels of human GBM cell lines propagated either as xenografts in nude mice or grown under conventional cell culture conditions confirmed that E-cadherin expression is rare. However, a small number of xenograft lines did express E-cadherin, its expression correlating with increased invasiveness when the cells were implanted orthotopically in mouse brain. In the conventionally cultured SF767 glioma cell line, E-cadherin expression was localized throughout the plasma membrane rather than being restricted to areas of cell-cell contact. ShRNA knockdown of E-cadherin in these cells resulted in decreased proliferation and migration in vitro. CONCLUSIONS/SIGNIFICANCE: Our data shows an unexpected correlation between the abnormal expression of E-cadherin in a subset of GBM tumor cells and the growth and migration of this aggressive brain tumor subtype

    Nonlinear analysis of biomagnetic signals recorded from uterine myomas

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    OBJECTIVE: To determine if there is any non-linearity in the biomagnetic recordings of uterine myomas and to find any differences that may be present in the mechanisms underlying their signal dynamics. METHODS: Twenty-four women were included in the study. Sixteen of them were characterised with large myomas and 8 with small ones. Uterine artery waveform measurements were evaluated by use of Pulsatility Index (PI) (normal value PI<1.45). RESULTS: Applying nonlinear analysis to the biomagnetic signals of the uterine myomas, we observed a clear saturation value for the group of large ones (mean = 11.35 ± 1.49) and no saturation for the small ones. CONCLUSION: The comparison of the saturation values in the biomagnetic recordings of large and small myomas may be a valuable tool in the evaluation of functional changes in their dynamic behavior

    Effects of a nanoscopic filler on the structure and dynamics of a simulated polymer melt and the relationship to ultra-thin films

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    We perform molecular dynamics simulations of an idealized polymer melt surrounding a nanoscopic filler particle to probe the effects of a filler on the local melt structure and dynamics. We show that the glass transition temperature TgT_g of the melt can be shifted to either higher or lower temperatures by appropriately tuning the interactions between polymer and filler. A gradual change of the polymer dynamics approaching the filler surface causes the change in the glass transition. We also find that while the bulk structure of the polymers changes little, the polymers close to the surface tend to be elongated and flattened, independent of the type of interaction we study. Consequently, the dynamics appear strongly influenced by the interactions, while the melt structure is only altered by the geometric constraints imposed by the presence of the filler. Our findings show a strong similarity to those obtained for ultra-thin polymer films (thickness 100\lesssim 100 nm) suggesting that both ultra-thin films and filled-polymer systems might be understood in the same context

    Transforming urinary stone disease management by artificial intelligence-based methods: A comprehensive review

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    Objective: To provide a comprehensive review on the existing research and evi-dence regarding artificial intelligence (AI) applications in the assessment and management of urinary stone disease.Methods: A comprehensive literature review was performed using PubMed, Scopus, and Google Scholar databases to identify publications about innovative concepts or supporting applica-tions of AI in the improvement of every medical procedure relating to stone disease. The terms "endourology", "artificial intelligence", "machine learning", and "urolithiasis"were used for searching eligible reports, while review articles, articles referring to automated procedures without AI application, and editorial comments were excluded from the final set of publica-tions. The search was conducted from January 2000 to September 2023 and included manu-scripts in the English language.Results: A total of 69 studies were identified. The main subjects were related to the detection of urinary stones, the prediction of the outcome of conservative or operative management, the optimization of operative procedures, and the elucidation of the relation of urinary stone chemistry with various factors.Conclusion: AI represents a useful tool that provides urologists with numerous amenities, which explains the fact that it has gained ground in the pursuit of stone disease management perfection. The effectiveness of diagnosis and therapy can be increased by using it as an alter-native or adjunct to the already existing data. However, little is known concerning the poten-tial of this vast field. Electronic patient records, containing big data, offer AI the opportunity to develop and analyze more precise and efficient diagnostic and treatment algorithms. Never-theless, the existing applications are not generalizable in real-life practice, and high-quality studies are needed to establish the integration of AI in the management of urinary stone dis-ease.CNN ; CNN
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