31 research outputs found
Unsteady stokes flow for a vibrating cantilever under a free-surface
No full textVibration of a thin, rectangular-cross-section beam submerged in a viscous, quiescent fluid undergoing small amplitude oscillations is studied using a Boundary Element (BE) approach in which the free-surface is modeled through a stress-free boundary condition. The Stokes approximation is used where nonlinear convective terms are negligible and the problem is formulated in Fourier and Laplace transform space when appropriate. Results are expressed in terms of nondimensional hydrodynamic force and its components, namely added mass and damping coefficients. Several parametric studies are conducted to evaluate the effects of depth of submergence, frequency and the amplitude of oscillations on the hydrodynamic functions. The results are compared with the classical solution for a vibrating lamina in an infinite fluid as the limit case and with a recent study using Smoothed Particle Hydrodynamics (SPH) analysis in the presence of a freesurface
La valutazione dell'esperienza di tirocinio : una ricerca preliminare nel Corso di Laurea in Fisioterapia
No full textLo scopo di questo studio è quello di analizzare i risultati ottenuti mediante l’analisi dei dati di un questionario
compilato dallo studente rispetto all’esperienza di tirocinio vissuta, con il preciso obiettivo di osservare i dati ottenuti
al fine di migliorare sia il processo di programmazione e pianificazione sia di verificare l’adeguatezza delle
sedi accreditate per l’esperienza clinica, nel rispetto e in coerenza con gli accordi stipulati in fase di convenzione.
Parole chiave: tirocinio professionalizzante, modelli di valutazione e di autovalutazione.
Summary
The purpose of this study is to examine student’s clinical perceptions of training experiences by the evaluation of a
questionnaire, in order to improve the clinical process and the planning of clinical teaching programme and quality.
Key words: professional training, evaluation and self-evaluation model
Position of nuclear medicine techniques in the diagnostic work-up of brain tumors
No full textAlthough any patient with a suspected brain tumor, either primary or metastatic, should be studied with anatomic imaging modalities such as angiography, computerized tomagraphy (CT) or magnetic resonance imaging (MRI), nuclear medicine techniques are available to further characterize some biological features of brain lesions and help in diagnosis and therapy planning. Bloob-brain-barrier disruption can be easily assessed with single-photon emission tomography (SPET), whereas focal metabolic changes can be better demonstrated by positron emission tomography (PET) as specific radiopharmaceuticals are available to detect changes in glucose utilization and aminoacid uptake with this technique. Expression of specific tumoral antigens is the basis of imaging with radioimmunoscintigraphy, a promising technique that can be applied to brain tumor therapy. The major clinical applications of nuclear medicine in the study of brain tumors -- evaluation of the extension of a tumoral mass, differential diagnosis and evaluation of therapy and prognosis -- are discussed
Smoothed Particle Hydrodynamics vs Lattice Boltzmann for the solution of steady and unsteady fluid flows
No full textNumerical simulations of steady and unsteady viscous flows are presented by adopting two different numerical methodologies: the Smoothed Particle Hydrodynamics formulation implemented in the open-source code DualSPHysics and an in-house lattice Boltzmann code based on a concise central-moments scheme. Both methods employ a weakly compressible assumption to simulate incompressible flow, which means the fluid is assumed barotropic and the density and pressure are related through an equation of state. The accuracy of the two approaches is evaluated against well-defined and consolidated benchmark tests. Advantages and disadvantages of the two methodologies are discussed and substantiated by quantitative comparisons that focus on accuracy and efficacy of the two methodologies against other well-established computational methods. Overall, both formulations proposed herein are able to capture the relevant flow physics with a good level of accuracy when compared to other more affirmed techniques. Remarkably, this is observed in spite of the proposed two methods lacking key strategies commonly used in grid-based methods, such as adaptive mesh refinement
Visceral Leishmaniasis Associated with B-Cell Chronic Lymphocytic Leukemia: Report of a Case and Review of the Literature
No full textClinicopathological Bird's-Eye View of Left Atrial Myocardial Fibrosis in 121 Patients with Persistent Atrial Fibrillation: Developing Architecture and Main Cellular Players
No full textBackground: Scientific research on atrial fibrosis in atrial fibrillation (AF) has mainly focused on quantitative or molecular features. The purpose of this study was to perform a clinicoarchitectural/structural investigation of fibrosis to provide one key to understanding the electrophysiological/clinical aspects of AF. Methods: We characterized the fibrosis (amount, architecture, cellular components, and ultrastructure) in left atrial biopsies from 121 patients with persistent/long-lasting persistent AF (group 1; 59 males; 60±11 years; 91 mitral disease-related AF, 30 nonmitral disease-related AF) and from 39 patients in sinus rhythm with mitral valve regurgitation (group 2; 32 males; 59±12 years). Ten autopsy hearts served as controls. Results: Qualitatively, the fibrosis exhibited the same characteristics in all cases and displayed particular architectural scenarios (which we arbitrarily subdivided into 4 stages) ranging from isolated foci to confluent sclerotic areas. The percentage of fibrosis was larger and at a more advanced stage in group 1 versus group 2 and, within group 1, in patients with rheumatic disease versus nonrheumatic cases. In patients with AF with mitral disease and no rheumatic disease, the percentage of fibrosis and the fibrosis stages correlated with both left atrial volume index and AF duration. The fibrotic areas mainly consisted of type I collagen with only a minor cellular component (especially fibroblasts/myofibroblasts; average value range 69-150 cells/mm2, depending on the areas in AF biopsies). A few fibrocytes-circulating and bone marrow-derived mesenchymal cells-were also detectable. The fibrosis-entrapped cardiomyocytes showed sarcolemmal damage and connexin 43 redistribution/internalization. Conclusions: Atrial fibrosis is an evolving and inhomogeneous histological/architectural change that progresses through different stages ranging from isolated foci to confluent sclerotic zones which-seemingly-constrain impulse conduction across restricted regions of electrotonically coupled cardiomyocytes. The fibrotic areas mainly consist of type I collagen extracellular matrix and, only to a lesser extent, mesenchymal cells
DualSPHysics: from fluid dynamics to multiphysics problems
No full textDualSPHysics is a weakly compressible smoothed particle hydrodynamics (SPH) Navier–Stokes solver initially conceived to deal with coastal engineering problems, especially those related to wave impact with coastal structures. Since the first release back in 2011, DualSPHysics has shown to be robust and accurate for simulating extreme wave events along with a continuous improvement in efficiency thanks to the exploitation of hardware such as graphics processing units for scientific computing or the coupling with wave propagating models such as SWASH and OceanWave3D. Numerous additional functionalities have also been included in the DualSPHysics package over the last few years which allow the simulation of fluid-driven objects. The use of the discrete element method has allowed the solver to simulate the interaction among different bodies (sliding rocks, for example), which provides a unique tool to analyse debris flows. In addition, the recent coupling with other solvers like Project Chrono or MoorDyn has been a milestone in the development of the solver. Project Chrono allows the simulation of articulated structures with joints, hinges, sliders and springs and MoorDyn allows simulating moored structures. Both functionalities make DualSPHysics especially suited for the simulation of offshore energy harvesting devices. Lately, the present state of maturity of the solver goes beyond single-phase simulations, allowing multi-phase simulations with gas–liquid and a combination of Newtonian and non-Newtonian models expanding further the capabilities and range of applications for the DualSPHysics solver. These advances and functionalities make DualSPHysics an advanced meshless solver with emphasis on free-surface flow modelling
What Do We Have to Know about PD-L1 Expression in Prostate Cancer? A Systematic Literature Review (Part 6): Correlation of PD-L1 Expression with the Status of Mismatch Repair System, BRCA, PTEN, and Other Genes
No full textPembrolizumab (anti-PD-1) is allowed in selected metastatic castration-resistant prostate cancer (PC) patients showing microsatellite instability/mismatch repair system deficiency (MSI-H/dMMR). BRCA1/2 loss-of-function is linked to hereditary PCs and homologous recombination DNA-repair system deficiency: poly-ADP-ribose-polymerase inhibitors can be administered to BRCA-mutated PC patients. Recently, docetaxel-refractory metastatic castration-resistant PC patients with BRCA1/2 or ATM somatic mutations had higher response rates to pembrolizumab. PTEN regulates cell cycle/proliferation/apoptosis through pathways including the AKT/mTOR, which upregulates PD-L1 expression in PC. Our systematic literature review (PRISMA guidelines) investigated the potential correlations between PD-L1 and MMR/MSI/BRCA/PTEN statuses in PC, discussing few other relevant genes. Excluding selection biases, 74/677 (11%) PCs showed dMMR/MSI; 8/67 (12%) of dMMR/MSI cases were PD-L1+. dMMR-PCs included ductal (3%) and acinar (14%) PCs (all cases tested for MSI were acinar-PCs). In total, 15/39 (39%) PCs harbored BRCA1/2 aberrations: limited data are available for PD-L1 expression in these patients. 13/137 (10%) PTEN-PCs were PD-L1+; 10/29 (35%) PD-L1+ PCs showed PTEN negativity. SPOP mutations may increase PD-L1 levels, while the potential correlation between PD-L1 and ERG expression in PC should be clarified. Further research should verify how the efficacy of PD-1 inhibitors in metastatic castration-resistant PCs is related to dMMR/MSI, DNA-damage repair genes defects, or PD-L1 expression
