679 research outputs found

    Simulations of aging and plastic deformation in polymer glasses

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    We study the effect of physical aging on the mechanical properties of a model polymer glass using molecular dynamics simulations. The creep compliance is determined simultaneously with the structural relaxation under a constant uniaxial load below yield at constant temperature. The model successfully captures universal features found experimentally in polymer glasses, including signatures of mechanical rejuvenation. We analyze microscopic relaxation timescales and show that they exhibit the same aging characteristics as the macroscopic creep compliance. In addition, our model indicates that the entire distribution of relaxation times scales identically with age. Despite large changes in mobility, we observe comparatively little structural change except for a weak logarithmic increase in the degree of short-range order that may be correlated to an observed decrease in aging with increasing load.Comment: 9 pages, 12 figure

    Non-Gaussian fluctuations in stochastic models with absorbing barriers

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    The dynamics of a one-dimensional stochastic model is studied in presence of an absorbing boundary. The distribution of fluctuations is analytically characterized within the generalized van Kampen expansion, accounting for higher order corrections beyond the conventional Gaussian approximation. The theory is shown to successfully capture the non Gaussian traits of the sought distribution returning an excellent agreement with the simulations, for {\it all times} and arbitrarily {\it close} to the absorbing barrier. At large times, a compact analytical solution for the distribution of fluctuations is also obtained, bridging the gap with previous investigations, within the van Kampen picture and without resorting to alternative strategies, as elsewhere hypothesized.Comment: 2 figures, submitted to Phys. Rev. Let

    A clinical pilot study on the effect of the probiotic Lacticaseibacillus rhamnosus TOM 22.8 strain in women with vaginal dysbiosis

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    Lactobacilli with probiotic features play an essential role in maintaining a balanced vaginal microbiota and their administration has been suggested for the treatment and prevention of vaginal dysbiosis. The present study was aimed to in vitro and in vivo investigate the probiotic potential of the Lacticaseibacillus rhamnosus TOM 22.8 strain, isolated from the vaginal ecosystem of a healthy woman. For this purpose, safety and functional properties were in depth evaluated. The strain exhibited a broad spectrum of antagonistic activity against vaginal pathogens; adhesion capacity to both the vaginal VK2/E6E7 and the intestinal Caco-2 cells; anti-inflammatory and antioxidant activities, suggesting its promising probiotic features. In addition, an in vivo pilot-study was planned. Based on both clinical and microbiological parameters, the oral or vaginal strain administration, determined a significant pathogens reduction after 10 days of administration and a maintenance of eubiosis up to 30 days after the end of the treatment. Therefore, the L. rhamnosus TOM 22.8 strain can be proposed as valuable oral and/or vaginal treatment for vaginal dysbiosis

    Post-Quake Small Italian Historical Centres: Urban Resilience between Rhetorics and Reality. The Case Study of Nocera Umbra after the 1997 Umbria-Marche Earthquakes

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    The small and medium Italian historical centres are characterized, among other things, by reconstruction that have occurred over the centuries after earthquakes. While earthquakes determine structural damages, human losses and loss of the functionality of an urban system above all, they may create, at the same time, new opportunities if the urban and socio-economical structures are improved during the reconstruction processes as a whole. These processes and the optimal implementation of planning models within them is not straightforward [1], due to that several issues emerge as a challenge of the reconstruction programmes (decision-making processes, general vision for the entire urban system for instance). According to the literature, although a unique definition has not still been coined, resilience can be defined as the capacity of a system (a city) to withstand and restore after a shocking episode (an earthquake). Mainly in the context of cities [2], some approaches have been framed and experimented by other authors [3, 4, 5]. Starting from a short literature review, focuses on theories and methodological approaches to evaluate urban resilience, this work analyses – through an interdisciplinary approach – the case study of Nocera Umbra twenty years after two devastating earthquakes occurred in 1997. The research represents a first attempt that aims at analysing if the implemented reconstruction strategies have made the urban system more resilient with respect to both the built and the socio-economic environment

    Hereditary Women’s Cancer: Management and Risk-Reducing Surgery

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    Hereditary women’s syndromes due to inherited mutations result in an elevated risk of developing gynecological cancers over the lifetime of affected carriers. The BRCA 1 and 2 mutations, Lynch syndrome (LS), and mutations in rare hereditary syndromes increase this risk and require more effective management of these patients based on surveillance and prophylactic surgery. Patients need counseling regarding risk-reducing surgery (RRS) and the time required to perform it, considering the adverse effects of premenopausal surgery and the hormonal effect on quality of life, bone density, sexual activity, and cardiological and vascular diseases. Risk-reducing salpingo-oophorectomy (RRSO) is the gold standard for BRCA-mutated patients. An open question is that of endometrial cancer (EC) risk in patients with BRCA1/2 mutation to justify prophylactic hysterectomy during RRSO surgical procedures. RRS provides a 90–95% risk reduction for ovarian and breast cancer in women who are mutation carriers, but the role of prophylactic hysterectomy is underinvestigated in this setting of patients. In this review, we evaluate the management of the most common hereditary syndromes and the benefits of risk-reducing surgery, particularly exploring the role of prophylactic hysterectomy

    Hyperthermic intraperitoneal chemotherapy in interval debulking surgery for advanced epithelial ovarian cancer: A single-center, real-life experience.

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    Background: An improvement in survival without increasing perioperative morbidity in patients with advanced epithelial ovarian cancer treated with hyperthermic intraperitoneal chemotherapy (HIPEC) after interval debulking surgery (IDS) has been recently demonstrated in a randomized controlled trial. This study was aimed at assessing the feasibility and perioperative outcomes of the use of HIPEC after IDS at a referral cancer center. Methods: Over the study period, 149 IDSs were performed. Patients who had at least International Federation of Gynecology and Obstetrics stage III disease, with <2.5 mm of residual disease (RD) at the end of surgery and were not participating in clinical trials received HIPEC. Moreover, specific exclusion criteria were considered. These patients were compared with 51 patients with similar clinical characteristics at the same institution and within the same timeframe who did not receive HIPEC. Results: No differences in patient or disease characteristics with the exception of the type of neoadjuvant chemotherapy (P =.002) were found between the 2 groups. As for surgical characteristics, significant differences were found in RD after IDS (P =.007) and in the duration of surgery (P <.001), whereas the bowel resection and diversion rates (P =.583 and P =.213, respectively) and the postoperative intensive care unit and hospital stays (P =.567 and P =.727, respectively) were comparable. The times to start adjuvant chemotherapy were also similar (P =.998). Equally, the rates of any grade of both intraoperative complications (P =.189) and early postoperative complications (P =.238) were superimposable. Conclusions: In the authors' experience, the addition of HIPEC to IDS is feasible in 35% for the population. This value might increase with changes in the inclusion/exclusion criteria. HIPEC does not increase perioperative complications and does not affect a patient's recovery or time to start adjuvant chemotherapy. HIPEC should be offered to select patients listed for IDS

    Assessment of Salvage Surgery in Persistent Cervical Cancer after Definitive Radiochemotherapy: A Systematic Review

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    Background and Objectives: The standard treatment approach in locally advanced cervical cancer (LACC) is exclusive concurrent chemoradiation therapy (RTCT). The risk of local residual disease after six months from RTCT is about 20–30%. It is directly related to relapse risk and poor survival, such as in patients with recurrent cervical cancer. This systematic review aims to describe studies investigating salvage surgery’s role in persistent/recurrent disease in LACC patients who underwent definitive RTCT. Materials and Methods: Studies were eligible for inclusion when patients had LACC with radiologically suspected or histologically confirmed residual disease after definitive RTCT, diagnosed with post-treatment radiological workup or biopsy. Information on complications after salvage surgery and survival outcomes had to be reported. The methodological quality of the articles was independently assessed by two researchers with the Newcastle–Ottawa scale. Following the recommendations in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, we systematically searched the PubMed, Scopus, Cochrane, Medline, and Medscape databases in May 2022. We applied no language or geographical restrictions but considered only English studies. We included studies containing data about postoperative complications and survival outcomes. Results: Eleven studies fulfilled the inclusion criteria and all were retrospective observational studies. A total of 601 patients were analyzed concerning the salvage surgery in LACC patients for persistent/recurrent disease after RTCT treatment. Overall, 369 (61.4%) and 232 (38.6%) patients underwent a salvage hysterectomy (extrafascial or radical) and pelvic exenteration (anterior, posterior, or total), respectively. Four hundred and thirty-nine (73%) patients had histologically confirmed the residual disease in the salvage surgical specimen, and 109 patients had positive margins (overall range 0–43% of the patients). The risk of severe (grade ≥ 3) postoperative complications after salvage surgery is 29.8% (range 5–57.5%). After a median follow-up of 38 months, the overall RR was about 32% with an overall death rate of 40% after hysterectomy or pelvic exenteration with or without lymphadenectomy. Conclusions: There is heterogeneity between the studies both in their design and results, therefore the effect of salvage surgery on survival and recurrence cannot be adequately estimated. Future homogeneous studies with an appropriately selected population are needed to analyze the safety and efficacy of salvage hysterectomy or pelvic exenteration in patients with residual tumors after definitive RTCT
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