301 research outputs found

    Relaxation of classical many-body hamiltonians in one dimension

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    The relaxation of Fourier modes of hamiltonian chains close to equilibrium is studied in the framework of a simple mode-coupling theory. Explicit estimates of the dependence of relevant time scales on the energy density (or temperature) and on the wavenumber of the initial excitation are given. They are in agreement with previous numerical findings on the approach to equilibrium and turn out to be also useful in the qualitative interpretation of them. The theory is compared with molecular dynamics results in the case of the quartic Fermi-Pasta-Ulam potential.Comment: 9 pag. 6 figs. To appear in Phys.Rev.

    Analysis of efficiency and profitability of franchise services

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    The present study analyses the relative efficiency of franchise services and characterises the best companies, confirming the relationship between efficiency and profit. These companies are from the trade and other services sector , the main group of service-providing companies in the Spanish economy. The methodology calls for first comparing the relative efficiency of franchisers and ownership enterprises. Second, the focus turns to the most efficient franchise services, using a super-efficiency model to rank them. The paper then goes on to cover the analysis of the main characteristics of the best franchise enterprises, the number of own establishments in a franchise business and the profitability of the company. This paper presents arguments as to why companies from the trade and other services sector are included. The main conclusion is that, whilst the number of establishments is irrelevant in achieving greater efficiency, many of the most efficient enterprises have high returns.García Martin, CJ.; Medal Bartual, A.; Peris-Ortiz, M. (2014). Analysis of efficiency and profitability of franchise services. Service Industries Journal. 34(9):796-810. doi:10.1080/02642069.2014.905921S79681034

    Initial Experience with Radical Prostatectomy Following Holmium Laser Enucleation of the Prostate

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    BACKGROUND: Although an increasing number of prostate cancer (PCa) patients received holmium laser enucleation of the prostate (HoLEP) previously for benign prostatic obstruction (BPO), there is still no evidence regarding the outcomes of radical prostatectomy (RP) in this setting. OBJECTIVE: To assess functional and oncological results of RP in PCa patients who received HoLEP for BPO previously in a contemporary multi-institutional cohort. DESIGN, SETTING, AND PARTICIPANTS: A total of 95 patients who underwent RP between 2011 and 2019 and had a history of HoLEP were identified in two institutions. Functional as well as oncological follow-up was prospectively assessed and retrospectively analyzed. INTERVENTION: RP following HoLEP compared with RP without previous transurethral surgery. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Patients with complete follow-up data were matched with individuals with no history of BPO surgery using propensity score matching. Complications were assessed using the Clavien-Dindo scale. RESULTS AND LIMITATIONS: The median follow-up was 50.5 mo. We found no significant impact of previous HoLEP on positive surgical margin rate (14.0% [HoLEP] vs 18.8% [no HoLEP], p =  0.06) and biochemical recurrence-free survival (hazard ratio 0.74, 95% confidence interval [CI] 0.32-1.70, p =  0.4). Patients with a history of HoLEP had increased 1-yr urinary incontinence rates after RP. After adjusting for confounders, no significant impact of previous HoLEP was found (odds ratio [OR] 0.87, 95% CI 0.74-1.01; p = 0.07). Previous HoLEP did not hamper 1-yr erectile function recovery (OR 1.22, 95% CI 1.05-1.43; p =  0.01). Limitations include retrospective design and small sample size. CONCLUSIONS: RP after previous HoLEP is surgically feasible, with low complication rates and no negative impact on biochemical recurrence-free survival. However, in a multivariable analysis, we observed significantly worse 1-yr continence rates in patients after previous HoLEP. PATIENT SUMMARY: In the current study, we assessed the oncological and functional outcomes of radical prostatectomy in patients who underwent holmium laser enucleation of the prostate (HoLEP) previously due to prostatic bladder outlet obstruction. A history of HoLEP did not hamper oncological results, 1-yr continence, and erectile function recovery

    Biomarkers to personalize treatment with 177Lu-PSMA-617 in men with metastatic castration-resistant prostate cancer - a state of the art review

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    Radioligand therapy with Lutetium-177 (177Lu)-Prostate-specific membrane antigen (PSMA) has shown to prolong survival in metastatic castration resistant prostate cancer (mCRPC). One of the major challenges for clinicians in the future is to select those patients who would benefit most from this therapy to position it in the treatment landscape of mCRPC. This, in turn, will lead to the delivery of personalized therapies. In this narrative review article we summarize recent studies investigating both predictive and prognostic clinical, imaging-based, and molecular biomarkers to predict treatment response to 177Lu-PSMA-617 radioligand therapy with the aim of identifying men who should be considered for this approach. Of note, the evidence on the role of biomarkers currently relies on small retrospective trials and their validation in larger prospective cohorts is necessary before these results can be translated in the clinical practice

    Multidimensional Facets of Perceived Risk in Mobile Travel Booking

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    Despite the growing prevalence of smartphones in daily life and travel context, travellers still perceive an extent of risk associated with using their smartphone to book travel products. In order to alleviate or reduce perceived risk, it is important to better understand the dimensions of and the factors that contribute to perceived risk. This study analysed 411 responses from an online panel to examine perceived risk in mobile travel booking and identified the following facets: time risk, financial risk, performance risk, privacy/security risk, psychological risk, physical risk, and device risk. Several antecedents of perceived risk were identified. Perceived collection of personal information via smartphones contributes positively, while consumer innovativeness, trust, and visibility contribute negatively to perceived risk. Further, the predictive validity of perceived risk is confirmed as it significantly explains perceived usefulness, attitude, and behavioural intention in mobile travel booking. Implications to manage perceived risk and its antecedents are provided

    Artesunate Impairs Growth in Cisplatin-Resistant Bladder Cancer Cells by Cell Cycle Arrest, Apoptosis and Autophagy Induction

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    Cisplatin, which induces DNA damage, is standard chemotherapy for advanced bladder cancer (BCa). However, efficacy is limited due to resistance development. Since artesunate (ART), a derivative of artemisinin originating from Traditional Chinese Medicine, has been shown to exhibit anti-tumor activity, and to inhibit DNA damage repair, the impact of artesunate on cisplatin-resistant BCa was evaluated. Cisplatin-sensitive (parental) and cisplatin-resistant BCa cells, RT4, RT112, T24, and TCCSup, were treated with ART (1–100 µM). Cell growth, proliferation, and cell cycle phases were investigated, as were apoptosis, necrosis, ferroptosis, autophagy, metabolic activity, and protein expression. Exposure to ART induced a time- and dose-dependent significant inhibition of tumor cell growth and proliferation of parental and cisplatin-resistant BCa cells. This inhibition was accompanied by a G0/G1 phase arrest and modulation of cell cycle regulating proteins. ART induced apoptos is by enhancing DNA damage, especially in the resistant cells. ART did not induce ferroptosis, but led to a disturbance of mitochondrial respiration and ATP generation. This impairment correlated with autophagy accompanied by a decrease in LC3B-I and an increase in LC3B-II. Since ART significantly inhibits proliferative and metabolic aspects of cisplatin-sensitive and cisplatin-resistant BCa cells, it may hold potential in treating advanced and therapy-resistant BCa

    COBRA framework to evaluate e-government services: A citizen-centric perspective

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    E-government services involve many stakeholders who have different objectives that can have an impact on success. Among these stakeholders, citizens are the primary stakeholders of government activities. Accordingly, their satisfaction plays an important role in e-government success. Although several models have been proposed to assess the success of e-government services through measuring users' satisfaction levels, they fail to provide a comprehensive evaluation model. This study provides an insight and critical analysis of the extant literature to identify the most critical factors and their manifested variables for user satisfaction in the provision of e-government services. The various manifested variables are then grouped into a new quantitative analysis framework consisting of four main constructs: cost; benefit; risk and opportunity (COBRA) by analogy to the well-known SWOT qualitative analysis framework. The COBRA measurement scale is developed, tested, refined and validated on a sample group of e-government service users in Turkey. A structured equation model is used to establish relationships among the identified constructs, associated variables and users' satisfaction. The results confirm that COBRA framework is a useful approach for evaluating the success of e-government services from citizens' perspective and it can be generalised to other perspectives and measurement contexts. Crown Copyright © 2014.PIAP-GA-2008-230658) from the European Union Framework Program and another grant (NPRP 09-1023-5-158) from the Qatar National Research Fund (amember of Qatar Foundation

    The scattering of SH waves by a finite crack with a superposition based diffraction technique

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    The problem of diffraction of cylindrical and plane SH waves by a finite crack is revisited -- We construct an approximate solution by the addition of independent diffracted terms -- We start with the derivation of the fundamental case of a semi-infinite crack obtained as a degenerate case of generalized wedge -- This building block is then used to compute the diffraction of the main incident waves -- The interaction between the opposite edges of the crack is then considered one term at a time until a desired tolerance is reached -- We propose a recipe to determine the number of required interactions as a function of frequency -- The solution derived with the superposition technique can be applied at low and high frequencie
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