503 research outputs found
DEATH BY VOLUNTARY CESSATION OF THERAPY BY NON-TERMINALLY ILL CYSTIC FIBROSIS PATIENTS - INTERNATIONAL SURVEY OF CLINICIANS
Background: Little is known about non-terminally ill cystic fibrosis (CF) patients who die by voluntary cessation of therapy. The current study was undertaken to provide an international snapshot of this problem. Methods: An online survey was distributed to the medical directors of the CF Centres affiliated with the US Cystic Fibrosis Foundation and Cystic Fibrosis Australia (with the inclusion of New Zealand); the same letter was sent to every clinician member of the European Cystic Fibrosis Society.
Results: More than 200 patients were reported as being in the situation described above. Data analysis was eligible in 102 patients (4 children, 25 adolescents and 73 adults). 92% were capable of judgement. Time-consuming and low immediate-impact therapies, such as respiratory physiotherapy, were most frequently discontinued first. Resignation was the main reported reason, followed by reactive depression and lack of familial support. 69% received palliative care and 72% died in the six months following refusal.
Conclusions: Death of non-terminally ill CF patients due to voluntary cessation of therapy exists. This challenging situation should be discussed in multi-disciplinary teams so that the most appropriate attitude, suited to the individual situation, is defined
Simulation of engagement control in automotive dry-clutch and temperature field analysis through finite element model
The tribological contact under sliding condition in the clutch facing surfaces during the engagement manoeuvre is strongly affected by heat transfer occurring in the system. The frictional forces acting on the contact surfaces produce mechanical energy losses which are converted in heat with ensuing temperature increase. Reports about the temperature rise after repeated clutch engagements prove the occurrence
of interface temperature peaks as high as 300 °C. Unfortunately, only few papers address their focus towards experiments and their outcomes about the influence of temperature and the other operating parameters on the frictional behaviour of the clutch facing materials.
In this paper, the Authors mainly explored the frictional behaviour modification for thermal level higher than 250–300 °C, whose effect is a sharp decline of the friction coefficient related to the decomposition of the phenol resin of the facings. Moreover, this phenomenon induces not expected transition from dry friction to mixed dry-lubricated friction which explains the reasons of the friction coefficient drop. The
temperature affects also the cushion spring load-deflection characteristic and the ensuing transmitted clutch torque. Thus, an original frictional map has been implemented in a control algorithm to estimate the heat flux during vehicle launch and up-shift manoeuvres. The results of the longitudinal vehicle dynamics has been used in a FEA to predict the temperature field during repeated clutch engagement on
the contact surfaces. The simulation results prove that during each engagement the interface temperature increases of 30–35 °C. This means that after only few repeated clutch engagements the temperature field could reach values near the critical point of 300 °C. In such a way, this paper aims at providing useful references to control engineers in order to improve the dry-clutch transmissions performances
Dry clutch for automated manual transmissions. Structural analysis and control strategies
2012 - 2013The goal of this thesis is the study of the automotive push-type dry clutches
used in the Automatic Manual Transmissions (AMTs) and in the Dual
Clutch Transmissions (DCTs) in order to improve their performances dur-
ing the engagements phases. The push-type clutch is very widespread in the
automotive sector because it allows many advantages in terms of cost, relia-
bility, isolation of vibrations to the driveline, reduced axial size and stability
to the facings wear [1]. Instead, the main advantages of an AMT, respect
to the Automatic Transmissions (ATs), are improvements in terms of safety,
reliability, and driving performances together with the reduction of the fuel
consumption and pollutant emissions [2]. For these reasons by mixing the
advantages of the push-type clutch with the advantages of the AMT it is
possible to attain very high performance [3, 4]. On the other hand, the
most important drawback of the AMT is the power interruption (the so
called "torque gap") during the gear shifts events. To solve this problem in
the last decade the DCTs have been introduced. In fact, by applying the
engine torque to one clutch just as the engine torque is being disconnected
from the other one [5] the torque transmission is allowed also during the
gear shift phases.
In this light, the work developed for this Thesis aimed at providing useful
information both to the clutch designers and to control algorithm designers
in order to enhance the performances, and consequently, the market di usion
mof the AMT and DCT transmissions.
The thesis is organized as follows. Chapter 2 is an introductory section on
the historical evolution of the clutches and of the automotive transmissions
systems. Chapter 3 deals with the transmissibility torque model by consid-
ering the main factors which a ect the elastic components of a push-type
clutch and the friction coe cient. In the Chapter 4 application of control
algorithms both for a two DoFs driveline model and for a ve DoFs model are introduced. Finally, the Chapter 5 underlines the concluding remarks. [edited by author]XII n.s
technical and economic analysis of pumps as turbines pats used in an italian water distribution network wdn for electrical energy production
Abstract The use of renewable resources is fundamental for achieving the emissions reduction targets. Small-scale hydropower is a viable solution that has only partially been exploited so far for producing electrical energy in rural/remote zones and for recovering energy where there is availability of pressure gradients and flow rates, like in Water Distribution Networks (WDNs) or in other industrial processes. In this paper, Pumps-as-Turbines (PaTs) are studied as a potential energy recovery and pressure regulation device, considering the case study of the Egna municipality WDN, a city located in the North of Italy. An innovative analytical approach is used for selecting PaTs, depending on WDN operating data, and for forecasting the machine performance under varying operating conditions. A MATLAB® Simulink model is developed for simulating two different set-ups configurations and installation of PaTs. Finally, an economic analysis is performed by evaluating the potential energy recovery and the PayBack Periods (PBPs)
Electric Motor and Dry Clutch Control in Launch Manoeuvres of Mild-Hybrid Vehicles Based on AMT/DCT Transmissions
Mild-Hybrid Electric Vehicles (mild-HEVs) earned market share over the last years an as effective roadmap to limit air pollution in big cities. In addition to this role, hybrid propulsion can be used to avoid dry clutch overheating in mild-HEVs equipped with automated manual transmissions. Indeed, high thermal level could result in serious damaging of dry clutch linings with very fast decay of expected lifespan affecting vehicle reliability. This paper shows results of vehicle launch simulations to highlight how the propulsion due to electric motor can effectively reduce clutch thermal stress during the slipping phase
Probucol treatment is associated with an ABCA1-independent mechanism of cholesterol efflux to lipid poor apolipoproteins from foam cell macrophages
Objective
Probucol is a cholesterol-lowering agent whose ability to prevent atherosclerosis is currently under study. Herein, we investigate the putative mechanism of probucol by observation of changes in cellular cholesterol efflux and lipid droplet morphology in macrophages.
Results
The inhibitory activity of probucol was assessed in non-foam or foam cell macrophages expressing ABCA1 generated by treatment with fetal calf serum (FCS) alone or in combination with acetylated LDL, respectively. Probucol inhibited cholesterol efflux to apolipoprotein A-I (apoA-I) by 31.5±0.1% in THP-1 non-foam cells and by 18.5±0.2% in foam cells. In probucol-treated non-foam THP-1 cells, nascent high-density lipoprotein (nHDL) particles with a diameter < 7 nm were generated, while in probucol-treated THP-1 foam cells nHDL particles of > 7 nm in diameter containing cholesterol were produced. Foam cells also displayed a significant accumulation of free cholesterol at the plasma membrane, as measured by percent cholestenone formed. Intracellularly, there was a significant decrease in lipid droplet number and an increase in size in probucol-treated THP-1 foam cells when compared to non-treated cells.
Conclusions
We report for the first time that probucol is unable to completely inhibit cholesterol efflux in foam cells to the same extent as in non-foam cells. Indeed, functional nHDL is released from foam cells in the presence of probucol. This difference in inhibitory effect could potentially be explained by changes in the plasma membrane pool as well as intracellular cholesterol storage independently of ABCA1
Design of a Programmable and Modular Neuromuscular Electrical Stimulator Integrated into a Wireless Body Sensor Network
Neuromuscular electrical stimulation finds application in several fields, from basic neurophysiology, to motor rehabilitation and cardiovascular conditioning. Despite the progressively increasing interest in this technique, its State-of-the-Art technology is mainly based on monolithic, mostly wired devices, leading to two main issues. First, these devices are often bulky, limiting their usability in applied contexts. Second, the possibility of interfacing these stimulation devices with external systems for the acquisition of electrophysiological and biomechanical variables to control the stimulation output is often limited. The aim of this work is to describe the design and development of an innovative electrical stimulator, specifically developed to contend with these issues. The developed device is composed of wireless modules that can be programmed and easily interfaced with third-party instrumentation. Moreover, benefiting from the system modular architecture, stimulation may be delivered concurrently to different sites while greatly reducing cable encumbrance. The main design choices and experimental tests are documented, evidencing the practical potential of the device in use-case scenarios
Opportunities and Limits of Conventional IVF versus ICSI: It Is Time to Come off the Fence
Conventional IVF (c-IVF) is one of the most practiced assisted reproductive technology (ART) approaches used worldwide. However, in the last years, the number of c-IVF procedures has dropped dramatically in favor of intracytoplasmic sperm injection (ICSI) in cases of non-male-related infertility. In this review, we have outlined advantages and disadvantages associated with c-IVF, highlighting the essential steps governing its success, its limitations, the methodology differences among laboratories and the technical progress. In addition, we have debated recent insights into fundamental questions, including indications regarding maternal age, decreased ovarian reserve, endometriosis, autoimmunity, single oocyte retrieval-cases as well as preimplantation genetic testing cycles. The “overuse” of ICSI procedures in several clinical situations of ART has been critically discussed. These insights will provide a framework for a better understanding of opportunities associated with human c-IVF and for best practice guidelines applicability in the reproductive medicine field
Rituximab-Based Treatment, HCV Replication, and Hepatic Flares
Rituximab, a chimeric mouse-human monoclonal antibody directed to the CD20 antigen expressed on pre-B lymphocytes and mature lymphocytes, causes a profound B-cell depletion. Due to its peculiar characteristics, this drug has been used to treat oncohaematological diseases, B cell-related autoimmune diseases, rheumatoid arthritis, and, more recently, HCV-associated mixed cryoglobulinaemic vasculitis. Rituximab-based treatment, however, may induce an increased replication of several viruses such as hepatitis B virus, cytomegalovirus, varicella-zoster virus, echovirus, and parvovirus B19. Recent data suggest that rituximab-based chemotherapy induces an increase in HCV expression in hepatic cells, which may become a target for a cell-mediated immune reaction after the withdrawal of treatment and the restoration of the immune control. Only a few small studies have investigated the occurrence of HCV reactivation and an associated hepatic flare in patients with oncohaematological diseases receiving R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). These studies suggest that the hepatic flares are frequently asymptomatic, but life-threatening liver failure occurs in nearly 10% of cases
Surveillance of clinical research integrity in medically assisted reproduction: a systematic review of retracted publications
Background and purpose
Retraction is a significant consequence of scientific research, resulting from various factors ranging from unintentional errors to intentional misconduct. Previous reviews on retracted publications in obstetrics and gynecology have identified “article duplication,” “plagiarism,” and “fabricated results” as the main reasons for retraction. However, the extent of retracted articles in the literature on medically assisted reproduction (MAR) remains unclear. This systematic review aimed to assess the number and characteristics of retracted articles in the field of MAR.
Methods
The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed for this study. A comprehensive literature search was conducted on the PubMed database from 1993 to February 2023, limited to English articles and including all 283 terms from the International Glossary on Infertility and Fertility Care. To identify retracted studies, a specific query combining the 283 terms from the glossary with a retraction-related keyword was used. Only studies focused on MAR and involving human subjects were included.
Results
The electronic search yielded a total of 523,067 records in the field of infertility and fertility care. Among these, a total of 2,458 records were identified as retracted. The citation retraction rate was found to be 0.47% (2,458/523,067; 95%CI 0.45–0.49), and the citation retraction rate for randomized controlled trials (RCTs) was 0.20% (93/45,616; 95%CI 0.16–0.25). A total of 39 retracted articles specifically related to MAR were identified. Among these, 41.0% were RCTs (n = 16), 15.4% were reviews (n = 6), and 10.3% were retrospective studies (n = 4) or prospective studies (n = 4). Most of the retractions occurred shortly after publication, with “plagiarism” being the most common reason for retraction, followed by “duplicate publication.”
Discussion
The issue of retraction exists within the field of infertility and fertility care, including MAR. Our findings indicate that scientific misconduct, particularly plagiarism and duplicate publication, are the primary causes of retraction in MAR. Despite finding that the proportion of retracted citations is low, promoting scientific integrity should be a priority. The consequences of article retractions have significant implications for patient care and the scientific community. Hence, it is crucial to prioritize thorough screening of manuscripts before publication to maintain research integrity.
Systematic review registration https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=185769, PROSPERO, identifier: CRD42020185769
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