103 research outputs found

    Robust isogeometric preconditioners for the Stokes system based on the Fast Diagonalization method

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    In this paper we propose a new class of preconditioners for the isogeometric discretization of the Stokes system. Their application involves the solution of a Sylvester-like equation, which can be done efficiently thanks to the Fast Diagonalization method. These preconditioners are robust with respect to both the spline degree and mesh size. By incorporating information on the geometry parametrization and equation coefficients, we maintain efficiency on non-trivial computational domains and for variable kinematic viscosity. In our numerical tests we compare to a standard approach, showing that the overall iterative solver based on our preconditioners is significantly faster.Comment: 31 pages, 4 figure

    Space-time least-squares isogeometric method and efficient solver for parabolic problems

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    In this paper, we propose a space-time least-squares isogeometric method to solve parabolic evolution problems, well suited for high-degree smooth splines in the space-time domain. We focus on the linear solver and its computational efficiency: thanks to the proposed formulation and to the tensor-product construction of space-time splines, we can design a preconditioner whose application requires the solution of a Sylvester-like equation, which is performed efficiently by the fast diagonalization method. The preconditioner is robust w.r.t. spline degree and mesh size. The computational time required for its application, for a serial execution, is almost proportional to the number of degrees-of-freedom and independent of the polynomial degree. The proposed approach is also well-suited for parallelization.Comment: 29 pages, 8 figure

    A low-rank isogeometric solver based on Tucker tensors

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    We propose an isogeometric solver for Poisson problems that combines i) low-rank tensor techniques to approximate the unknown solution and the system matrix, as a sum of a few terms having Kronecker product structure, ii) a Truncated Preconditioned Conjugate Gradient solver to keep the rank of the iterates low, and iii) a novel low-rank preconditioner, based on the Fast Diagonalization method where the eigenvector multiplication is approximated by the Fast Fourier Transform. Although the proposed strategy is written in arbitrary dimension, we focus on the three-dimensional case and adopt the Tucker format for low-rank tensor representation, which is well suited in low dimension. We show in numerical tests that this choice guarantees significant memory saving compared to the full tensor representation. We also extend and test the proposed strategy to linear elasticity problems.Comment: 27 pages, 8 figure

    The Effect of Using Secang (Caesalpinia secang Linn) Infusion on the Organoleptic Quality of Chicken Sausage

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    This study aims to determine the effect of using Secang infusion (Caesalpinia secang Linn) on the organoleptic quality of chicken sausages and determine the optimal level of adding Secang infusion on the organoleptic quality of chicken sausages. This research was carried out in 30 days at the Laboratory of the Faculty of Animal Husbandry, University of Jambi. This study used a randomized block design (RBD) which consisted of 4 treatments and 30 replications (panelists). The concentration of Secang infusion used was 0%, 5%, 10%, and 15%. The variables observed in this study were the value of organoleptic quality, which included color, aroma, taste, texture, and elasticity. The data obtained were analyzed by analysis of variance (ANOVA). If it had a significant effect, it continued with Duncan's test. The results showed that the use of Secang infusion on chicken sausage had a very significant effect (P<0.01) on color but had no effect (P>0.05) on aroma, taste, texture, and elasticity. The higher the concentration of  Secang infusion, the more preferred the sausage color will be. It can be concluded that the processing of chicken sausage with the addition of Secang infusion at 10% and 15% level produced the preferred color of the panelist's preference level compared to the 0% and 5% levels. Still, the addition of Secang in the processing of chicken sausage did not make a difference to the level of preference for aroma, taste, texture, and suppleness

    Nonpegylated liposomal doxorubicin combination regimen in patients with diffuse large B-cell lymphoma and cardiac comorbidity. Results of the HEART01 phase II trial conducted by the Fondazione Italiana Linfomi

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    The purpose of this phase 2, multicenter study was to determine the activity and safety of nonpegylated liposomal doxorubicin as part of "R-COMP" combination in patients with diffuse large B-cell lymphoma and coexisting cardiac disorders. The study was conducted using a Bayesian continuing assessment method using complete remission rate and rate of cardiac events as study endpoints. Between November 2009 and October 2011, 50 evaluable patients were enrolled (median age, 76\ua0years). Median baseline left ventricular ejection fraction (LVEF) was 60%. Ischemic cardiopathy was the most frequent preexisting cardiac disorder (35%), followed by atrial fibrillation (15%), left ventricular hypertrophy (13%), and baseline LVEF <50% (12%). Based on the intent to treat analysis, overall response rate was 72%, including 28 patients in complete remission (complete remission rate, 56%), and 8 in partial remission (16%). At the end of treatment, grades 3 to 4 cardiac events were observed in 6 patients. No significant modifications from baseline values of LVEF were observed during treatment and follow-up. Nonpegylated liposomal doxorubicin instead of doxorubicin in the R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) regimen is a feasible option for patients with diffuse large B-cell lymphoma presenting with concomitant cardiac disorders

    Histological verification of positive positron emission tomography findings in the follow-up of patients with mediastinal lymphoma.

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    Background and Objectives Follow-ups of patients with mediastinal lymphoma are not accurate if they rely on computed tomography (CT). Positron emission tomography (PET) has been suggested to be useful in several lymphoma settings, such as initial staging, evaluation of residual masses after therapy, and assessment of response early in the course of treatment. The aim of this retrospective study was to verify the reliability of positive PET scans of the mediastinum in following up patients wirh mediastinal lymphoma, using histological findings as a comparison. Design and Methods From January 2002 to July 2005, 151 patients with mediastinal lymphoma (57 with Hodgkin's disease [HD] and 94 with aggressive non-Hodgkin's lymphoma [NHL]) were followed-up after the end of front-line treatment. Patients with a positive PET scan of the mediastinum underwent CT scanning and surgical biopsy. Results In 30 (21 HD and 9 NHL) out of 151 patients (20%) a suspicion of lymphoma relapse was raised based on positive mediastinal PET scanning. Histology confirmed this suspicion in 17 (10 HD and 7 NHL) out of 30 patients (57%), whereas either benign (9 fibrosis, 3 sarcoid-like granulomatosis) or unrelated neoplastic conditions (1 thymoma) were demonstrated in the remaining 13 patients (43%). SUVmax was significantly higher among patients who had signs of relapse (17 true positive cases) than among those who stayed in remission (13 false positive cases), the median values being 5.95 (range, 3.5–26.9) and 2.90 (range, 1.4–3.3), respectively ( p =0.01). Interpretation and Conclusions We suggest that a positive PET scan of the mediastinum of a patient being followed-up for a mediastinal lymphoma should not be considered sufficient for diagnostic purposes in view of its lack of discrimination. Histological confirmation can safely be carried out with various biopsy techniques, the choice of which should be made on the basis of the findings of the clinical and imaging studies of the individual case

    Efficacy and safety of subcutaneous and intravenous rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone in first-line diffuse large B-cell lymphoma: The randomized MabEase study

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    I Intravenous rituximab plus chemotherapy is standard treatment for diffuse large B-cell lymphoma. A subcutaneous formulation of rituximab is expected to simplify and shorten drug preparation and administration, and to reduce treatment burden. MabEase (clinicaltrials.gov Identifier: 01649856) examined efficacy, safety and patient satisfaction with subcutaneous rituximab plus chemotherapy in treatment- naïve patients with diffuse large B-cell lymphoma. Patients were randomized 2:1 to subcutaneous rituximab (intravenous 375 mg/m2 cycle 1; subcutaneous 1,400 mg cycles 2-8) or intravenous rituximab (375 mg/m2 cycles 1-8) plus cyclophosphamide, doxorubicin, vincristine, and prednisone every 14 or 21 days. The primary endpoint was investigatorassessed complete response/unconfirmed complete response. Secondary endpoints included safety, treatment satisfaction (Cancer Treatment Satisfaction Questionnaire and Rituximab Administration Satisfaction Questionnaire), time savings, and survival. Of 576 randomized patients, 572 (378 subcutaneous; 194 intravenous) received treatment. End of induction complete response/unconfirmed complete response rates were 50.6% (subcutaneous) and 42.4% (intravenous). After a median 35 months, median overall, event-free and progression-free survivals were not reached. Grade ≥3 adverse events (subcutaneous 58.3%; intravenous 54.3%) and administration-related adverse events (both groups 21%) were similar between arms. Injection-site reactions were more common with subcutaneous injections (5.7% versus 0%, respectively). Rituximab Administration Satisfaction Questionnaire scores for ‘impact on activities of daily living’, ‘convenience’, and ‘satisfaction’ were improved with subcutaneous versus intravenous injections; Cancer Therapy Satisfaction Questionnaire scores were similar between arms. Median administration time (6 minutes vs. 2.6 to 3.0 hours), chair/bed and overall hospital times were shorter with subcutaneous versus intravenous rituximab. Overall, subcutaneous and intravenous rituximab had similar efficacy and safety, with improved patient satisfaction and time savings
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