46 research outputs found

    Woltjer-Taylor State Without Taylor's Conjecture - Plasma Relaxation at all Wavelengths

    Full text link
    In astrophysical and laboratory plasmas, it has been discovered that plasmas relax towards the well-known Woltjer-Taylor state specified by ∇ x B = αB for a constant α . To explain how such a relaxed state is reached, Taylor developed his famous relaxation theory based on the conjecture that the relaxation is dominated by short wavelength fluctuations. However, there is no conclusive experimental and numerical evidence to support Taylor's conjecture. A new theory is developed, which predicts that the system will evolve towards the Woltjer-Taylor state for an arbitrary fluctuation spectrum

    Bilateral stenting methods for hilar biliary obstructions

    Get PDF
    OBJECTIVE: There is no consensus regarding the most appropriate methods (i.e., the side-by-side versus the stent-in-stent technique) for placing bilateral stents for malignant hilar biliary obstructions. We aimed to perform a quantitative review of the published data regarding the clinical efficacy of the side-by-side and stentinstent bilateral drainage techniques for hilar biliary obstructions. METHODS: A comprehensive search of several databases was conducted and a fixed-effects or random-effects model was used to pool the data from all of the study end-points. RESULTS: Four clinical trials were identified. A comparison of the side-by-side and stent-in-stent groups revealed no significant differences with respect to the rates of successful placement, successful drainage, early complications, late complications and stent occlusions. There were also no significant inter-group differences in stent patency and patient survival and no publication bias was observed. CONCLUSIONS: The performance of the side-by-side technique appears to be similar to that of the stent-instent technique for bilateral drainage in patients with malignant hilar biliary obstructions

    Involvement of the exocrine pancreas during covid-19 infection and possible pathogenetic hypothesis: a concise review

    Get PDF
    The gastrointestinal system may be affected by COVID-19 infection with an incidence variable from 3% up to 79%. Several works show that the pancreas, both in its exocrine and endocrine function, can be affected by this viral infection, although this organ has been poorly analyzed in this current epidemic context. This mini-review aims to provide a summary of available studies on exocrine pancreas involvement during COVID-19 infection. A search through MEDLINE/PubMed was conducted on the topic in hand. With regard to exocrine function, some studies highlight the presence of an associated hyperenzymemia (hyperamylasemia, hyperlipasemia), while others describe isolated and rare cases of acute pancreatitis. More attention should be paid to pancreatic impairment in subjects with COVID-19, as this may prove to be one of the elements aggravating its clinical course. Indeed, acute pancreatitis, especially when presenting in severe forms with hyperstimulation of the pro-inflammatory response, may represent a crucial factor in the progression of COVID-19, entailing both an increase in hospitalization days and in mortality rate

    SARS-CoV-2 vaccines: What we know, what we can do to improve them and what we could learn from other well-known viruses

    Get PDF
    : In recent weeks, the rate of SARS-CoV-2 infections has been progressively increasing all over the globe, even in countries where vaccination programs have been strongly implemented. In these regions in 2021, a reduction in the number of hospitalizations and deaths compared to 2020 was observed. This decrease is certainly associated with the introduction of vaccination measures. The process of the development of effective vaccines represents an important challenge. Overall, the breakthrough infections occurring in vaccinated subjects are in most cases less severe than those observed in unvaccinated individuals. This review examines the factors affecting the immunogenicity of vaccines against SARS-CoV-2 and the possible role of nutrients in modulating the response of distinct immune cells to the vaccination
    corecore