278 research outputs found

    New results on the stability of quasi-static paths of a single particle system with Coulomb friction and persistent contact

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    In this paper we announce some new mathematical results on the stability of quasi-static paths of a single particle linearly elastic system with Coulomb friction and persistent normal contact with a flat obstacle.A quasi-static path is said to be stable at some value of the load parameter if, for some finite interval of the load parameter thereafter, the dynamic solutions behave continuously with respect to the size of the initial perturbations (as in Lyapunov stability) and to the smallness of the rate of application of the external forces, Δ\varepsilon (as in singular perturbation problems). In this paper we prove sufficient conditions for stability of quasi-static paths of a single particle linearly elastic system with Coulomb friction and persistent normal contact with a flat obstacle. The present system has the additional difficulty of its non-smoothness: the friction law is a multivalued operator and the dynamic evolutions of this system may have discontinuous accelerations

    Massnahmen zur PrĂ€vention und FrĂŒherkennung des Urothelkarzinoms der Harnblase

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    Das Urothelkarzinom der Harnblase gehört zu den 10 hĂ€ufigsten Krebserkrankungen weltweit. Die Verteilung der Risikofaktoren, Möglichkeiten der FrĂŒherkennung, Diagnostik und Therapie variieren je nach Region stark. Die Behandlungsform und InvasivitĂ€t der Therapie sowie auch deren Prognose sind stark abhĂ€ngig vom initialen Tumorstadium. Die wichtigsten Risikofaktoren fĂŒr die Entstehung eines Urothelkarzinoms der Harnblase umfassen das Rauchen und die berufliche Exposition zu aromatischen Aminen oder chlorierten sowie polyzyklisch-aromatischen Kohlenwasserstoffen in der Industrie. Die Bestrebungen der Arbeitsmedizin im Verlauf der letzten Jahrzehnte haben zu einer deutlichen Risikoreduktion von exponierten Arbeitnehmenden gefĂŒhrt. Die BemĂŒhungen in der Anbindung von Patienten an Rauchentwöhnungsprogramme mĂŒssen hingegen noch weiter intensiviert werden. Nur gerade ein Drittel der Raucher mit Diagnose eines Urothelkarzinoms der Harnblase schaffen es, im weiteren Verlauf den Rauchabusus komplett zu sistieren. Ein Screening wird aufgrund der vergleichsweise niedrigen Inzidenz und der kurzen Vorlaufzeit der Erkrankung nicht empfohlen. Hingegen sollten Patienten mit dem Symptom einer schmerzlosen MakrohĂ€maturie in jedem Fall auf das Vorliegen eines Karzinoms im unteren oder oberen Urogenitaltrakt abgeklĂ€rt werden. FĂŒr die DurchfĂŒhrung einer grĂŒndlichen Diagnostik ist die Zuweisung an einen Urologen sinnvoll. = Le carcinome urothĂ©lial de la vessie fait partie des 10 cancers les plus frĂ©quents Ă  l’échelle mondiale. La distribution des facteurs de risque, les possibilitĂ©s de dĂ©pistage prĂ©coce, de diagnostic et de thĂ©rapie varient fortement d’une rĂ©gion Ă  l’autre. La forme de traitement et l’invasivitĂ© de la thĂ©rapie ainsi que le pronostic dĂ©pendent beaucoup du stade initial de la tumeur. Les principaux facteurs de risque prĂ©disposant Ă  un carcinome urothĂ©lial de la vessie comprennent le tabagisme et l’exposition professionnelle aux amines aromatiques ou aux hydrocarbures aromatiques chlorĂ©s et polycycliques dans le cadre de l’industrie. Les efforts de la mĂ©decine du travail au cours des derniĂšres dĂ©cennies ont permis une nette rĂ©duction du risque chez le personnel exposĂ©. D’autre part, les efforts pour intĂ©grer les patients Ă  des programmes de sevrage tabagique doivent ĂȘtre intensifiĂ©s encore davantage. Seulement un tiers des fumeurs avec un diagnostic de carcinome urothĂ©lial de la vessie parvient Ă  se sevrer entiĂšrement du tabac. En raison de l’incidence relativement faible de la maladie et de la courte durĂ©e de son stade prĂ©curseur, un dĂ©pistage de masse n’est pas recommandĂ©. En revanche, les patients prĂ©sentant le symptĂŽme d’une macrohĂ©maturie indolore doivent en tout cas ĂȘtre examinĂ©s quant Ă  la prĂ©sence d’un carcinome urothĂ©lial du tractus gĂ©nito-urinaire infĂ©rieur ou supĂ©rieur. Pour des investigations approfondies, il est judicieux d’adresser les patients Ă  un urologue

    Index lesion contouring on prostate MRI for targeted MRI/US fusion biopsy - Evaluation of mismatch between radiologists and urologists

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    PURPOSE: Mistargeting of focal lesions due to inaccurate segmentations can lead to false-negative findings on MRI-guided targeted biopsies. The purpose of this retrospective study was to examine inter-reader agreement of prostate index lesion segmentations from actual biopsy data between urologists and radiologists. METHOD: Consecutive patients undergoing transperineal MRI-targeted prostate biopsy for PI-RADS 3-5 lesions between January 2020 and December 2021 were included. Agreement between segmentations on T2w-images between urologists and radiologists was assessed with Dice similarity coefficient (DSC) and 95 % Hausdorff distance (95 % HD). Differences in similarity scores were compared using Wilcoxon test. Differences depending on lesion features (size, zonal location, PI-RADS scores, lesion distinctness) were tested with Mann-Whitney U test. Correlation with prostate signal-intensity homogeneity score (PSHS) and lesion size was tested with Spearman's rank correlation. RESULTS: Ninety-three patients (mean age 64.9 ± 7.1y, median serum PSA 6.5 [4.33-10.00]) were included. Mean similarity scores were statistically significantly lower between urologists and radiologists compared to radiologists only (DSC 0.41 ± 0.24 vs. 0.59 ± 0.23, p < 0.01; 95 %HD 6.38 ± 5.45 mm vs. 4.47 ± 4.12 mm, p < 0.01). There was a moderate and strong positive correlation between DSC scores and lesion size for segmentations from urologists and radiologists (ρ = 0.331, p = 0.002) and radiologists only (ρ = 0.501, p < 0.001). Similarity scores were worse in lesions ≀ 10 mm while other lesion features did not significantly influence similarity scores. CONCLUSION: There is significant mismatch of prostate index lesion segmentations between urologists and radiologists. Segmentation agreement positively correlates with lesion size. PI-RADS scores, zonal location, lesion distinctness, and PSHS show no significant impact on segmentation agreement. These findings could underpin benefits of perilesional biopsies

    Ordinal Prototype-Based Classifiers

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    The identification of prototypical patterns is one of the major goals in the classification of microarray data. Prototype-based classifiers are of special interest in this context, since they allow a direct biological interpretation. In this work we present prototype-based classifiers that rely on ordinal-scaled data. Advantage of these ordinal-scaled signatures is their invariance to a wide range of data transformations. Standard prototype-based classifiers can be modified to this type of data by utilizing rank-distances and rank-aggregation procedures. In this study, we compare the proposed methods with standard classifiers. They are examined in experiments with and without feature selection on a panel of publicly available microarray datasets. We show that the proposed techniques result in the construction of different signatures that improve classification performance

    Improved Prostate-Specific Membrane Antigen (PSMA) Stimulation Using a Super Additive Effect of Dutasteride and Lovastatin In Vitro

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    Prostate-specific membrane antigen (PSMA)-based imaging improved the detection of primary, recurrent and metastatic prostate cancer. However, in certain patients, a low PSMA surface expression can be a limitation for this promising diagnostic tool. Pharmacological induction of PSMA might be useful to further improve the detection rate of PSMA-based imaging. To achieve this, we tested dutasteride (Duta)-generally used for treatment of benign prostatic enlargement-and lovastatin (Lova)-a compound used to reduce blood lipid concentrations. We aimed to compare the individual effects of Duta and Lova on cell proliferation as well as PSMA expression. In addition, we tested if a combination treatment using lower concentrations of Duta and Lova can further induce PSMA expression. Our results show that a treatment with ≀1 ÎŒM Duta and ≄1 ÎŒM Lova lead to a significant upregulation of whole and cell surface PSMA expression in LNCaP, C4-2 and VCaP cells. Lower concentrations of Duta and Lova in combination (0.5 ÎŒM Duta + 0.5 ÎŒM Lova or 0.5 ÎŒM Duta + 1 ÎŒM Lova) were further capable of enhancing PSMA protein expression compared to a single compound treatment using higher concentrations in all tested cell lines (LNCaP, C4-2 and VCaP)

    Stress Urinary Incontinence: An Unsolved Clinical Challenge

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    Stress urinary incontinence is still a frequent problem for women and men, which leads to pronounced impairment of the quality of life and withdrawal from the social environment. Modern diagnostics and therapy improved the situation for individuals affected. But there are still limits, including the correct diagnosis of incontinence and its pathophysiology, as well as the therapeutic algorithms. In most cases, patients are treated with a first-line regimen of drugs, possibly in combination with specific exercises and electrophysiological stimulation. When conservative options are exhausted, minimally invasive surgical therapies are indicated. However, standard surgeries, especially the application of implants, do not pursue any causal therapy. Non-absorbable meshes and ligaments have fallen into disrepute due to complications. In numerous countries, classic techniques such as colposuspension have been revived to avoid implants. Except for tapes in the treatment of stress urinary incontinence in women, the literature on randomized controlled studies is insufficient. This review provides an update on pharmacological and surgical treatment options for stress urinary incontinence; it highlights limitations and formulates wishes for the future from a clinical perspective

    Contrast media kinetics in multiparametric magnetic resonance imaging before radical prostatectomy predicts the probability of postoperative incontinence.

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    PURPOSE To evaluate the role of preoperative multiparametric magnetic resonance imaging (MRI) as predictor of post-prostatectomy incontinence (PPI). METHODS We analyzed patients who underwent robot-assisted radical prostatectomy for localized prostate cancer at our institution between July 2015 and April 2017. In these patients, we measured the perfusion quality of the pelvic floor with contrast media kinetics in the preoperative MRI of the prostate and compared the levator ani muscle (region of interest) to the surrounding pelvic muscle structures (reference). Prospectively collected questionnaires regarding urinary incontinence were then evaluated 1 year postoperatively. Outcomes were dichotomized into "continent" (ICIQ-Score = 0-5) and "incontinent" (ICIQ-Score ≄ 6). In each patient, we determined the perfusion ratio of the levator ani muscle divided by the surrounding pelvic muscle structures and compared them among the groups. RESULTS Forty-two patients were included in the study (n = 22 in "continent", n = 20 in "incontinent" group). The median perfusion ratio from the continent group was significantly higher compared to the incontinent group (1.61 vs. 1.15; 95% CI 0.09-0.81, p = 0.015). The median perfusion ratio in "excellent" (ICIQ-Score = 0) was significantly higher than in "poor" (ICIQ-Score ≄ 11) outcomes (1.48 vs. 0.94; 95% CI 0.04-1.03, p = 0.036). Further, a higher perfusion ratio was negatively correlated with ICIQ-Score (r = - 0.33; 95% CI - 0.58 to 0.03; p = 0.031). CONCLUSIONS Our data demonstrate a promising new strategy to predict PPI through the perfusion quality of pelvic muscle structures with contrast media kinetics. This may facilitate preoperative patient consulting and decision-making

    The European Forest and Agriculture Optimisation Model -- EUFASOM

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    Land use is a key factor to social wellbeing and has become a major component in political negotiations. This paper describes the mathematical structure of the European Forest and Agricultural Sector Optimization Model. The model represents simultaneously observed resource and technological heterogeneity, global commodity markets, and multiple environmental qualities. Land scarcity and land competition between traditional agriculture, forests, nature reserves, pastures, and bioenergy plantations is explicitly captured. Environmental change, technological progress, and policies can be investigated in parallel. The model is well-suited to estimate competitive economic potentials of land based mitigation, leakage, and synergies and trade-offs between multiple environmental objectives.Land Use Change Optimization, Resource Scarcity, Market Competition, Welfare Maximization, Bottom-up Partial Equilibrium Analysis, Agricultural Externality Mitigation, Forest Dynamics, Global Change Adaptation, Environmental Policy Simulation, Integrated Assessment, Mathematical Programming, GAMS

    Long-Term Oncological Efficacy of Retroperitoneoscopic Radical Nephrectomy of Localized Renal Cell Cancer pT1-3 (≀12 cm)

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    Investigation of oncological efficacy in retroperitoneoscopic radical nephrectomy (RRN) of patients with localized renal cell carcinoma (RCC). Consecutive patients undergoing RRN for localized stage pT1-3 RCC in 2 tertiary care centers in Switzerland were evaluated. Excellent long-term oncological efficacy was found. Our long-term follow-up validates the survival outcome from comparable literature after conventional open or laparoscopic radical nephrectomy
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