Fractional Spectral Moments for Digital Simulation of Multivariate Wind Velocity Fields

In this paper, a method for the digital simulation of wind velocity fields by Fractional Spectral Moment function is proposed. It is shown that by constructing a digital filter whose coefficients are the fractional spectral moments, it is possible to simulate samples of the target process as superposition of Riesz fractional derivatives of a Gaussian white noise processes. The key of this simulation technique is the generalized Taylor expansion proposed by the authors. The method is extended to multivariate processes and practical issues on the implementation of the method are reported.Comment: 12 pages, 2 figure

Infliximab to treat Crohn's disease: an update

Abstract: Crohn’s disease (CD) is a chronic inflammatory disease of the gastrointestinal tract characterized by recurring flares followed by periods of inactive disease and remission. The etiology is unknown, although the common opinion is that the disease arises from a disordered immune response to the gut contents in genetically predisposed individuals. Infliximab (IFX), a chimeric immunoglobulin G1 monoclonal antibody to tumor necrosis factor, has dramatically changed the approach to managing patients with CD and improving their treatment, by achieving treatment goals, such as mucosal healing, and decreasing the need for hospitalizations and surgeries. This review provides an update on existing evidence for the use of IFX in CD, taking into account the safety profile in clinical practice and special situations such as pregnancy. Antitumor necrosis factor therapy has been evaluated as an induction and maintenance therapy in CD in several randomized controlled trials and meta-analyses, showing efficacy in both clinical settings. Early use of biologics may improve patient outcomes in active CD. However, a widespread use of a “top-down” approach in all CD patients cannot be recommended. Clinical factors at diagnosis may predict poor outcome in CD, and should be taken into account when determining the initial therapeutic approach. Keywords: Crohn’s disease, infliximab, adul

Systematic review: macrophage activation syndrome in inflammatory bowel disease

BACKGROUND: Recently, there have been increasingly frequent reports on the occurrence of macrophage activation syndrome (MAS) in patients with inflammatory bowel disease (IBD). Clinically, MAS is characterized mainly by fever, hepatosplenomegaly, cytopenia, and elevated circulating ferritin and CD25. Mortality, even if diagnosed rapidly, is high. AIM: To identify all reports on MAS in IBD and to establish data on triggering agents, immunosuppression leading to MAS, and mortality. METHODS: A language unrestricted search on Pubmed and Scopus relating to the past 30 years was carried out by matching the following search-terms: h(a)emophagocytic lymphohistiocytosis OR h(a)emophagocytic lymphohistiocytic syndrome OR macrophage activation syndrome OR opportunistic infections OR cytomegalovirus OR Epstein-Barr virus AND Crohn's disease OR ulcerative colitis OR inflammatory bowel disease(s). RESULTS: Fifty cases were identified with an overall mortality of 30%. Virus-related MAS associated with cytomegalovirus or Epstein-Barr virus infections represents the main type of MAS, but in isolated cases bacterial infections precipitated the syndrome. In four cases (8%), a lymphoma was present at the time of MAS diagnosis or developed shortly thereafter. Thiopurine monotherapy was given before MAS onset in 56% of the patients, whereas multiple immunosuppression, including biologics, was administered to 24%. CONCLUSIONS: In IBD patients, the syndrome appears to be triggered by infections, but genetic susceptibility may contribute to its development. Since immunosuppressive therapy represents the backbone of therapeutic interventions in IBD, with the risk of new, or the reactivation of latent infections, even more frequent cases of macrophage activation syndrome may be expected

Heart failure and anti tumor necrosis factor-alpha in systemic chronic inflammatory diseases.

Tumor necrosis factor alpha (TNF-alpha) antagonists have emerged as an effective therapy for patients with diseases as Crohn's disease, rheumatoid arthritis, and other chronic systemic inflammatory diseases. In the last years, there has been a growing interest in the role that inflammatory cytokines, which sustain the pathogenesis of these diseases, plays in regulating cardiac structure and function, particularly in the progression of chronic heart failure. In fact there is an increase of anti-TNF alpha levels in advanced heart failure but the treatment with anti-TNF alpha has been shown to worsen the prognosis of heart failure in randomized controlled trials. Patients with rheumatoid arthritis have an increased risk for cardiovascular disease and anti-TNF alpha therapy seems to be beneficial on the risk of cardiovascular disease. In Crohn's disease the increased risk of cardiovascular disease is controversial and therefore it is impossible to demonstrate an effect in reduction of the risk; however, heart failure in patients treated with anti-TNF alpha, despite in a small proportion, has been observed. On the basis of this observation, anti-TNF alpha therapy is contraindicated in patients with Crohn's disease and III-IV New York Heart Association heart failure class