A space-time discretization of a nonlinear peridynamic model on a 2D lamina

Peridynamics is a nonlocal theory for dynamic fracture analysis consisting in a second order in time partial integro-differential equation. In this paper, we consider a nonlinear model of peridynamics in a two-dimensional spatial domain. We implement a spectral method for the space discretization based on the Fourier expansion of the solution while we consider the Newmark-$\beta$ method for the time marching. This computational approach takes advantages from the convolutional form of the peridynamic operator and from the use of the discrete Fourier transform. We show a convergence result for the fully discrete approximation and study the stability of the method applied to the linear peridynamic model. Finally, we perform several numerical tests and comparisons to validate our results and provide simulations implementing a volume penalization technique to avoid the limitation of periodic boundary conditions due to the spectral approach

Computation of Eigenvalues for Nonlocal Models by Spectral Methods

The purpose of this work is to study spectral methods to approximate the eigenvalues of nonlocal integral operators. Indeed, even if the spatial domain is an interval, it is very challenging to obtain closed analytical expressions for the eigenpairs of peridynamic operators. Our approach is based on the weak formulation of eigenvalue problem and we consider as orthogonal basis to compute the eigenvalues a set of Fourier trigonometric or Chebyshev polynomials. We show the order of convergence for eigenvalues and eigenfunctions in $L^2$-norm, and finally, we perform some numerical simulations to compare the two proposed methods

Numerical Methods for the Nonlocal Wave Equation of the Peridynamics

In this paper we will consider the peridynamic equation of motion which is described by a second order in time partial integro-differential equation. This equation has recently received great attention in several fields of Engineering because seems to provide an effective approach to modeling mechanical systems avoiding spatial discontinuous derivatives and body singularities. In particular, we will consider the linear model of peridynamics in a one-dimensional spatial domain. Here we will review some numerical techniques to solve this equation and propose some new computational methods of higher order in space; moreover we will see how to apply the methods studied for the linear model to the nonlinear one. Also a spectral method for the spatial discretization of the linear problem will be discussed. Several numerical tests will be given in order to validate our results

Covid-19 And Rheumatic Autoimmune Systemic Diseases: Role of Pre-Existing Lung Involvement and Ongoing Treatments

The Covid-19 pandemic may have a deleterious impact on patients with autoimmune systemic diseases (ASD) due to their deep immune-system alterations

Computation of Eigenvalues for Nonlocal Models by Spectral Methods

The purpose of this work is to study spectral methods to approximate the eigenvalues of nonlocal integral operators. Indeed, even if the spatial domain is an interval, it is very chal-lenging to obtain closed analytical expressions for the eigenpairs of peridynamic operators. Our approach is based on the weak formulation of eigenvalue problem and in order to com-pute the eigenvalues we consider an orthogonal basis consisting of a set of Fourier trigono-metric or Chebyshev polynomials. We show the order of convergence for eigenvalues and eigenfunctions in L2-norm, and finally, we perform some numerical simulations to compare the two proposed methods

Palliative treatment of bone metastases with samarium-153 EDTMP at onset of pain

We evaluated the pain response and daily discomfort in patients suffering from a borderline degree of bone pain due to breast or lung cancer bone metastases, who had undergone early palliative radionuclide treatment. The results were compared with those from patients who had received standard analgesic therapy. Twenty-one patients (65.7 +/- A 3 years; 17 women) with metastatic bone cancer underwent samarium-153 (Sm-153) ethylene diamine tetramethylene phosphonate (EDTMP) administration (group A) and 18 patients (64.3 +/- A 8 years; 16 women) continued to receive standard analgesics (group B; control group). The patients kept a daily pain diary assessing both their discomfort and the pain at specific sites by means of a visual analog scale, rating from 0 (no discomfort-no pain) to 10 (worst discomfort-pain). These diaries were reviewed weekly for 2 months and three physicians rated the pain response on a scale from -2 (considerable deterioration) to +2 (considerable improvement). Baseline characteristics were similar in both groups. The reduction of total discomfort and of bone pain in group A was significantly greater compared to group B (p < 0.0001). A significant improvement of clinical conditions was observed in group A, where the physician rate changed from -1 to 1, compared to group B in which the rate changed from -1 to 0. Sm-153 EDTMP therapy can be considered for patients with bone pain from breast and lung cancer in advance, i.e., before the establishment of severe pain syndrome

Linguaggio e apprendimento linguistico. Metodi e strumenti tecnologici

Negli ultimi decenni, il legame tra la linguistica applicata e le scienze tecnologiche dell’informazione e della comunicazione (TIC) è divenuto più forte e articolato. Entrambe le discipline si intersecano contribuendo l’una al potenziamento dell’altra, in un rapporto reciproco e fecondo. La stretta connessione tra le TIC e la linguistica applicata si realizza nella ricerca, nelle pratiche comunicative e nella didattica, ambiti che scansionano l’organizzazione interna del volume. I lavori presentati in questo volume mirano a rispondere a quesiti di sicuro interesse scientifico, ivi inclusi: Quali sono i processi di apprendimento della pronuncia in L2? Qual è la struttura del discorso mediato dal computer? Quali sono le regolarità pragmatiche della comunicazione nei messaggi di posta elettronica? Quali sono le caratteristiche delle nuove forme di interazione nelle reti sociali virtuali? Come devono essere strutturati i dizionari online per apprendenti di L2? Come si può costruire un ambiente di apprendimento collaborativo tramite l’impiego di social network? Il volume è di sicuro interesse per la ricerca e per la didattica linguistica. Il ricercatore vi troverà una pluralità di prospettive di analisi che si ascrivono agli ambiti di ricerca di linguistica applicata. Il docente di lingua troverà spunti per innovare l’insegnamento linguistico assegnando alle tecnologie un posto di rilievo al passo con i tempi e con gli interessi dei giovani studenti

Dual Functionalized Liposomes for Selective Delivery of Poorly Soluble Drugs to Inflamed Brain Regions

Dual functionalized liposomes were developed to cross the blood–brain barrier (BBB) and to release their cargo in a pathological matrix metalloproteinase (MMP)-rich microenvironment. Liposomes were surface-functionalized with a modified peptide deriving from the receptor-binding domain of apolipoprotein E (mApoE), known to promote cargo delivery to the brain across the BBB in vitro and in vivo; and with an MMP-sensitive moiety for an MMP-triggered drug release. Different MMP-sensitive peptides were functionalized at both ends with hydrophobic stearate tails to yield MMP-sensitive lipopeptides (MSLPs), which were assembled into mApoE liposomes. The resulting bi-functional liposomes (i) displayed a −5 cm/min; (iii) when exposed to functional MMP2 or 9, efficiently released an encapsulated fluorescein dye; (iv) showed high biocompatibility when tested in neuronal cultures; and (v) when loaded with glibenclamide, a drug candidate with poor aqueous solubility, reduced the release of proinflammatory cytokines from activated microglial cells

Prevalence and death rate of COVID-19 in systemic autoimmune diseases in the first three pandemic waves. Relationship to disease subgroups and ongoing therapies

Objective: Autoimmune systemic diseases (ASD) represent a predisposing condition to COVID-19. Our prospective, observational multicenter telephone survey study aimed to investigate the prevalence, prognostic factors, and outcomes of COVID-19 in Italian ASD patients. Methods: The study included 3,918 ASD pts (815 M, 3103 F; mean age 59 +/- 12SD years) consecutively recruited between March 2020 and May 2021 at the 36 referral centers of COVID-19 and ASD Italian Study Group. The possible development of COVID-19 was recorded by means of a telephone survey using a standardized symptom assessment questionnaire. Results: ASD patients showed a significantly higher prevalence of COVID-19 (8.37% vs. 6.49%; p<0.0001) but a death rate statistically comparable to the Italian general population (3.65% vs. 2.95%). Among the 328 ASD patients developing COVID-19, 17% needed hospitalization, while mild-moderate manifestations were observed in 83% of cases. Moreover, 12/57 hospitalized patients died due to severe interstitial pneumonia and/or cardiovascular events; systemic sclerosis (SSc) patients showed a significantly higher COVID-19-related death rate compared to the general population (6.29% vs. 2.95%; p=0.018). Major adverse prognostic factors to develop COVID-19 were: older age, male gender, SSc, pre-existing ASD-related interstitial lung involvement, and long-term steroid treatment. Of note, patients treated with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) showed a significantly lower prevalence of COVID-19 compared to those without (3.58% vs. 46.99%; p=0.000), as well as the SSc patients treated with low dose aspirin (with 5.57% vs. without 27.84%; p=0.000). Conclusion: During the first three pandemic waves, ASD patients showed a death rate comparable to the general population despite the significantly higher prevalence of COVID-19. A significantly increased COVID-19-related mortality was recorded in only SSc patients' subgroup, possibly favored by preexisting lung fibrosis. Moreover, ongoing long-term treatment with csDMARDs in ASD might usefully contribute to the generally positive outcomes of this frail patients' population