2,082 research outputs found
Dynamic response of structures to thunderstorm outflows: Response spectrum technique vs time-domain analysis
Thunderstorms are transient events. Design wind velocity and wind-induced damage are often related to them. Despite this, research on thunderstorm loading of structures is still fragmentary and uncertain due to their complexity, short duration and small size. These issues make it difficult to set physically realistic and simple models as well as to gather real data. This favoured the implementation of refined methods based on limited measurements. The European Projects \u201cWind and Ports\u201d and \u201cWind, Ports and Sea\u201d realised an extensive monitoring network from which many thunderstorm outflow records were extracted. They were analysed to inspect their characteristics and to formulate methods coherent with measurements. Firstly, the response spectrum technique conceived for earthquakes was extended to thunderstorms. Then, a hybrid simulation strategy was proposed and time-domain integrations of the structural response were applied. This paper provides a joint calibration and advancement of these two methods, leading to results that substantially agree, especially faced with their conceptual and operative diversities. This confirms the potential of the response spectrum technique to become a suitable tool for calculating the thunderstorm loading of structures and the efficiency of hybrid simulations and time-domain analyses to investigate, with a limited computational burden, advanced structural issues
Structural response to non-stationary thunderstorm out-flows: multi-variate vs equivalent mono-variate simulation
The European Projects \u201cWind and Ports\u201d and \u201cWind, Ports and Sea\u201d gave rise to an extensive wind monitoring network in the High Tyrrhenian Sea area, from which many records of thunderstorm outflows were extracted. Initially, they were analysed to inspect their statistical properties. Later on, a hybrid multi-variate strategy for simulating the non-stationary wind field of the thunderstorm outflows was formulated and implemented to determine the time-domain response of structures. This paper shows the conceptual and numeric simplifications involved by embedding the equivalent wind spectrum technique, a method developed in a stationary framework, within the above non-stationary
formulation. It leads to generate a multi-variate non-stationary wind field through the simulation of a mono-variate stationary process, without any relevant loss of precision
Multicomponent dispersion of hydrocarbons at sea: Source term evaluation and hydrodynamic simulation of the spill
The evaluation of the ecological consequences of spill accidents including factors such as persistence, and long-term exposure became more stringent following some notable events and still represents an up-to-date research issue. This study focuses on the possibility of proper source identification of a multi component sea spill and is motivated by actual findings of small quantities of floating and/or stranded waxy material in some areas of Liguria and Tuscany, in early summer 2017. The paper presents a thorough hydrodynamic simulation, carried out with an oil-spill Lagrangian particle model to study the trajectories of the different released material and determine its probable source. A short-cut mathematical simulation of the step-by-step process of formation by on-board activities and subsequent water interaction is proposed so as to highlight the limitations and the potential applicability of the method, also in light of setting-up early warning systems to prevent stranding of the oil slick in sensitive coast environments
Optimization of Graphene-Based Materials Outperforming Host Epoxy Matrices
The degree of graphite exfoliation and edge-carboxylated layers can be controlled and balanced to design lightweight materials characterized by both low electrical percolation thresholds (EPT) and improved mechanical properties. So far, this challenging task has been undoubtedly very hard to achieve.
The results presented in this paper highlight the effect of exfoliation degree and the role of edge-carboxylated graphite layers to give self-assembled structures embedded in the polymeric matrix. Graphene layers inside the matrix may serve as building blocks of complex systems that could outperform the host matrix. Improvements in electrical percolation and mechanical performance have been obtained by a synergic effect due to finely balancing the degree of exfoliation and the chemistry of graphene edges which favors the interfacial interaction between polymer and carbon layers.
In particular, for epoxy-based resins including two partially exfoliated graphite samples, differing essentially in the content of carboxylated groups, the percolation threshold reduces from 3 wt% down to 0.3 wt%, as the carboxylated group content increases up to 10 wt%. Edge-carboxylated nanosheets also increase the nanofiller/epoxy matrix interaction, determining a relevant reinforcement in the elastic modulus
Endoscopic sinusectomy: ‘a rose by any other name’. A systematic review of different endoscopic procedures to treat pilonidal disease
Aim Pilonidal sinus or Pilonidal Disease (PD) is a relatively common, benign but challenging condition. Although commonly encountered in practice, its ideal treatment is controversial. One of the most validated treatments is video-assisted surgery. In this context, very similar endoscopic techniques have been published under different names. The aim of this systematic review is to assess the differences among these proposed techniques and their outcomes. Methods The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed during all stages of this systematic review. A systematic search of the English literature was performed on multiple databases from 1 January 2014 to 3 April 2022. The primary outcome measure was the IDEAL framework stage of innovation. The key secondary outcome measures were the adherence to the IDEAL reporting guidelines, the Blencowe framework and the core outcome set (COS) for studies evaluating the introduction and evaluation of novel surgical techniques, the qualitative assessment using appropriate tools, the procedural variations and outcomes of each technique. Results A total of 38 articles were included reporting a very similar technique under eight different acronyms. The number of patients varied from 9 to 250. Mean follow-up ranged from 1 to 60 months. There was only one published study of IDEAL 3. The majority (58%) were IDEAL 2a studies. Reporting of domains in the IDEAL reporting guidelines and Blencowe framework was poor, with most studies not reporting the component steps of procedures or efforts to standardize them. Half of COS domains were markedly underreported. The quality of the evidence was categorized as having a risk of bias from moderate to critical level in all nine comparative non-randomized series. Postoperative complications occurred in 0%-6% of cases, including surgical site infection, poor or failed wound healing bleeding, granuloma, haematoma, and pain requiring intervention. The recurrence rate varied from 0% to 22%. Conclusion The study demonstrates that reporting on technical aspects of interventions for PD is poor, thus warranting a better-quality control of surgical techniques. It is advisable to group all endoscopic procedures under the umbrella term of 'endoscopic sinusectomy', thus embracing the two main principles of this technique, that is, video assistance and PD ablation
Pyrosequencing Unveils Cystic Fibrosis Lung Microbiome Differences Associated with a Severe Lung Function Decline
Chronic airway infection is a hallmark feature of cystic fibrosis (CF) disease. In the present study, sputum samples from CF patients were collected and characterized by 16S rRNA gene-targeted approach, to assess how lung microbiota composition changes following a severe decline in lung function. In particular, we compared the airway microbiota of two groups of patients with CF, i.e. patients with a substantial decline in their lung function (SD) and patients with a stable lung function (S). The two groups showed a different bacterial composition, with SD patients reporting a more heterogeneous community than the S ones. Pseudomonas was the dominant genus in both S and SD patients followed by Staphylococcus and Prevotella. Other than the classical CF pathogens and the most commonly identified non-classical genera in CF, we found the presence of the unusual anaerobic genus Sneathia. Moreover, the oligotyping analysis revealed the presence of other minor genera described in CF, highlighting the polymicrobial nature of CF infection. Finally, the analysis of correlation and anti-correlation networks showed the presence of antagonism and ecological independence between members of Pseudomonas genus and the rest of CF airways microbiota, with S patients showing a more interconnected community in S patients than in SD ones. This population structure suggests a higher resilience of S microbiota with respect to SD, which in turn may hinder the potential adverse impact of aggressive pathogens (e.g. Pseudomonas). In conclusion, our findings shed a new light on CF airway microbiota ecology, improving current knowledge about its composition and polymicrobial interactions in patients with CF
Pulmonary Artery Catheter Monitoring in Patients with Cardiogenic Shock: Time for a Reappraisal?
Cardiogenic shock represents one of the most dramatic scenarios to deal with in intensive cardiology care and is burdened by substantial short-term mortality. An integrated approach, including timely diagnosis and phenotyping, along with a well-established shock team and management protocol, may improve survival. The use of the Swan-Ganz catheter could play a pivotal role in various phases of cardiogenic shock management, encompassing diagnosis and haemodynamic characterisation to treatment selection, titration and weaning. Moreover, it is essential in the evaluation of patients who might be candidates for long-term heart-replacement strategies. This review provides a historical background on the use of the Swan-Ganz catheter in the intensive care unit and an analysis of the available evidence in terms of potential prognostic implications in this setting
Prognostic Factors for Overall Survival In Chronic Myeloid Leukemia Patients: A Multicentric Cohort Study by the Italian CML GIMEMA Network
An observational prospective study was conducted by the CML Italian network to analyze the role of baseline patient characteristics and first line treatments on overall survival and CML-related mortality in 1206 newly diagnosed CML patients, 608 treated with imatinib (IMA) and 598 with 2nd generation tyrosine kinase inhibitors (2GTKI). IMA-treated patients were much older (median age 69 years, IQR 58-77) than the 2GTKI group (52, IQR 41-63) and had more comorbidities. Estimated 4-year overall survival of the entire cohort was 89% (95%CI 85.9-91.4). Overall, 73 patients (6.1%) died: 17 (2.8%) in the 2GTKI vs 56 (9.2%) in the IMA cohort (adjusted HR=0.50; 95% CI=0.26-0.94), but no differences were detected for CML-related mortality (10 (1.7%) vs 11 (1.8%) in the 2GTKIs vs IMA cohort (sHR=1.61; 0.52-4.96). The ELTS score was associated to CML mortality (high risk vs low, HR=9.67; 95%CI 2.94-31.74; p<0.001), while age (per year, HR=1.03; 95%CI 1.00-1.06; p=0.064), CCI (4-5 vs 2, HR=5.22; 95%CI 2.56-10.65; p<0.001), ELTS score (high risk vs low, HR=3.11; 95%CI 1.52-6.35, p=0.002) and 2GTKI vs IMA (HR=0.26; 95%CI 0.10-0.65, p=0.004) were associated to an increased risk of non-related CML mortality. The ELTS score showed a better discriminant ability than the Sokal score in all comparisons
The clinical effectiveness of an integrated multidisciplinary evidence-based program to prevent intraoperative pressure injuries in high-risk children undergoing long-duration surgical procedures: a quality improvement study
The prevention of hospital-acquired pressure injuries (HAPIs) in children undergoing long-duration surgical procedures is of critical importance due to the potential for catastrophic sequelae of these generally preventable injuries for the child and their family. Long-duration surgical procedures in children have the potential to result in high rates of HAPI due to physiological factors and the difficulty or impossibility of repositioning these patients intraoperatively. We developed and implemented a multi-modal, multi-disciplinary translational HAPI prevention quality improvement program at a large European Paediatric University Teaching Hospital. The intervention comprised the establishment of wound prevention teams, modified HAPI risk assessment tools, specific education, and the use of prophylactic dressings and fluidized positioners during long-duration surgical procedures. As part of the evaluation of the effectiveness of the program in reducing intraoperative HAPI, we conducted a prospective cohort study of 200 children undergoing long-duration surgical procedures and compared their outcomes with a matched historical cohort of 200 children who had undergone similar surgery the previous year. The findings demonstrated a reduction in HAPI in the intervention cohort of 80% (p < 0.01) compared to the comparator group when controlling for age, pathology, comorbidity, and surgical duration. We believe that the findings demonstrate that it is possible to significantly decrease HAPI incidence in these highly vulnerable children by using an evidence-based, multi-modal, multidisciplinary HAPI prevention strategy
An approach to prevent frailty in community dwelling older adults: a pilot study performed in Campania region in the framework of the PERSSILAA project
We developed and tested an innovative physical
training method in older adults that embeds the gym
program into everyday life in the most conservative
way possible. Physical training was included in the
activities of local parishes where older women from
Southern Italy spend most of their free time and was
delivered by trained physical therapists with the
support of an ICT tool known as CoCo. 113 older
women (aged 72.0 [69.0-75.0] years) noncompliant
to conventional exercise programs participated to
the study. 57 of them underwent the final
anthropometric assessment and 50 the final physical
tests. In study completers handgrip strength and
physical performance evaluated with the chair-stand,
the two minutes step and the chair-sit and -reach
tests significantly improved. Quality of life as
evaluated with the EuroQol-5dimension (EQ-5D)
questionnaire improved as well. In conclusion, a
training program designed to minimally impact on
life habits of older people is effective in improving
fitness in patients noncompliant to other to physical
exercise programs
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