5,472 research outputs found

    Feasibility of friction stir welding using a hemispherical tool tilted towards the retreating side

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    The use of a hemispherical tool tilted towards the retreating side for friction stir welding 6061-T6 aluminum alloy is investigated. Joints with smooth surfaces and without internal voids are obtained. Under the same welding and rotational speeds, adapting the tilt angle makes it possible to weld various thicknesses up to 3.5 mm. Plunge depth and tilt angle are demonstrated to be key geometrical parameters driving material flow when using the hemispherical tool. Microstructural features in the weld are equiaxed and refined grains below 5 µm in the stirred zone and narrow thermo-mechanical affected zones. The through-thickness thermomechanical gradient developing beneath the hemispherical tool leads to different extents of dynamic recrystallization and recovery in the stirred zone. The tool orientation towards the retreating side and the division of the tool-workpiece interaction in continuous and intermittent contact leads to an asymmetrical thermal field around the stirred zone. Hence, the new derivative friction stir welding solution allows the welding of multiple aluminum alloy blank thicknesses using the same tool

    Conceptual design of 20 T hybrid accelerator dipole magnets

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    International audienceHybrid magnets are currently under consideration as an economically viable option towards 20 T dipole magnets for next generation of particle accelerators. In these magnets, High Temperature Superconducting (HTS) materials are used in the high field part of the coil with so-called insert coils, and Low Temperature Superconductors (LTS) like Nb3Sn and Nb-Ti superconductors are used in the lower field region with so-called outsert coils. The attractiveness of the hybrid option lays on the fact that, on the one hand, the 20 T field level is beyond the Nb3Sn practical limits of 15-16 T for accelerator magnets and can be achieved only via HTS materials; on the other hand, the high cost of HTS superconductors compared to LTS superconductors makes it advantageous exploring a hybrid approach, where the HTS portion of the coil is minimized. We present in this paper an overview of different design options aimed at generating 20 T field in a 50 mm clear aperture. The coil layouts investigated include the Cos-theta design (CT), with its variations to reduce the conductor peak stress, namely the Canted Cos-theta design (CCT) and the Stress Management Cos-theta design (SMCT), and, in addition, the Block-type design (BL) including a form of stress management and the Common-Coil design (CC). Results from a magnetic and mechanical analysis are discussed, with particular focus on the comparison between the different options regarding quantity of superconducting material, field quality, conductor peak stress, and quench protection

    Seven Years of Culture Collection of Neisseria gonorrhoeae: Antimicrobial Resistance and Molecular Epidemiology

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    The emergence of Neisseria gonorrhoeae isolates displaying resistance to antimicrobials, in particular to ceftriaxone monotherapy or ceftriaxone plus azithromycin, represents a global public health concern. This study aimed to analyze the trend of antimicrobial resistance in a 7-year isolate collection retrospective analysis in Italy. Molecular typing on a subsample of gonococci was also included. A total of 1,810 culture-positive gonorrhea cases, collected from 2013 to 2019, were investigated by antimicrobial susceptibility, using gradient diffusion method, and by the N. gonorrhoeae multiantigen sequence typing (NG-MAST). The majority of infections occurred among men with urogenital infections and 57.9% of male patients were men who have sex with men. Overall, the cefixime resistance remained stable during the time. An increase of azithromycin resistance was observed until 2018 (26.5%) with a slight decrease in the last year. In 2019, gonococci showing azithromycin minimum inhibitory concentration above the EUCAST epidemiological cutoff value (ECOFF) accounted for 9.9%. Ciprofloxacin resistance and penicillinase-producing N. gonorrhoeae (PPNG) percentages increased reaching 79.1% and 18.7% in 2019, respectively. The most common sequence types identified were 5,441, 1,407, 6,360, and 5,624. The predominant genogroup (G) was the 1,407; moreover, a new genogroup G13070 was also detected. A variation in the antimicrobial resistance rates and high genetic variability were observed in this study. The main phenotypic and genotypic characteristics of N. gonorrhoeae isolates were described to monitor the spread of drug-resistant gonorrhea

    Laparoscopic entry techniques: which should you prefer?

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    Background: Despite a debate spanning two decades, no consensus has been achieved about the safest laparoscopic entry technique. Objectives: To update the evidence about the safety of the main different laparoscopic entry techniques. Search strategy: Six electronic databases were searched from inception to February 2021. Selection criteria: All randomized controlled trials (RCTs) comparing different laparoscopic entry techniques were included. Data collection and analysis: Entry-related complications and total time for entry were compared among the different methods of entry calculating pooled odds ratios (ORs) and mean differences, with 95% confidence intervals (CIs); P < 0.05 was considered significant. Main results: In total, 25 RCTs (6950 patients) were included. Complications considered were vascular, visceral and omental injury, failed entry, extraperitoneal insufflation, bleeding and infection at the trocar site bleeding, and incisional hernia. Compared to direct trocar, the OR for Veress needle was significantly higher for omental injury (OR 3.65, P < 0.001), for failed entry (OR 4.19, P < 0.001), and for extraperitoneal insufflation (OR 5.29, P < 0.001). Compared to the open method, the OR for Veress needle was significantly higher for omental injury (OR 4.93, P = 0.001), for failed entry (OR 2.99, P < 0.001), for extraperitoneal insufflation (OR 4.77; P = 0.04), and for incisional hernia. Compared to the open method, the OR for direct trocar was significantly lower for visceral injury (OR 0.17, P = 0.002) and for trocar site infection (OR 0.27, P = 0.001). Conclusions: The direct trocar method may be preferred over Veress needle and open methods as a laparoscopic entry technique since it appears associated to a lower risk of complications

    Transizioni

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    Questo quarto volume del Centro “Ricerche di Gnoseologia e Metafisica”, sin dall’immagine di copertina, raffigurante la giovane Europa sul dorso del toro, manifesta il proprio tema portante, che dà il titolo all’opera: Transizioni. La violenza del ratto, pur innegabile e inarrestabile, avviene lentamente e gradualmente: così siamo appunto noi nel divenire e, a fortiori, nel contingente, in una condizione di “transizione”, una condizione liminale dai bordi costantemente sfumati in cui la sfida è affrontare questa “traduzione” (sia in senso fisico-etimologico, che metaforico) con tutto ciò che essa implica e con tutti i suoi aspetti chiaroscurali (un po’ crepuscolari, un po’ aurorali). Una “transizione” di cui l’essere umano è massimamente capace, nonché protagonista, in quanto assomma al mutare quella capacità astrattiva e quell’autocoscienza che gli consentono di domandarsi “chi sono io?” (un “chi” che si trasforma in un “dove” metafisico ed esistenziale nel tableau dell’essere) e, nello slittamento tra il non-più-del-passato e il non-ancora-del-futuro, di gestire questa metamorfosi senza perdere se stesso e il mondo, trasformando il mutare in “performare”, ovvero muoversi tra e con le forme e mantenere il “filo narrativo” dell’esistenza. Plasmandosi e plasmando, “agendo-nel-farsi-della-realtà” e della storia (e non solo retrospettivamente), l’essere umano pone le condizioni di possibilità di una filosofia dell’azione e della liberazione propriamente detta. Questa è la cornice tematica in cui si collocano i molteplici interventi del volume, cui hanno contribuito tanto i membri e le/i collaboratrici/tori del Centro RGM, quanto alcune/i studiose/i di fama internazionale che hanno partecipato alle attività e iniziative di quest’ultimo.This fourth volume of the "Research of Gnoseology and Metaphysics" Centre, since the cover image, depicting young Europe on the back of the bull, manifests its main theme, which gives the work its title: Transitions. The violence of the rape, although undeniable and unstoppable, occurs slowly and gradually: this is precisely how we are in the process of becoming and, a fortiori, in the contingent, in a condition of "transition", a liminal condition in which the challenge is to face this "translation" (both in a physical-etymological and metaphorical sense) with all that it implies and with all its crepuscular and auroral aspects. A "transition" of which the human being is fully capable, as well as protagonist, as it adds to the change that abstractive capacity and self-awareness that allow him to ask himself "who am I?" (a “who” that transforms into a metaphysical and existential “where” in the tableau of being) and, in the slippage between the no longer-of-the-past and the not-yet-of-the-future, to manage this metamorphosis without losing himself and the world, transforming changing into "performing", that is, moving between and with forms and maintaining the "narrative thread" of existence. By shaping and molding, "acting-in-the-making-of-reality" and history (and not only retrospectively), the human being sets the conditions of possibility for a philosophy of action and liberation properly speaking. This is the thematic framework in which the multiple interventions of the volume are placed, to which the members and collaborators of the RGM Center contributed, as well as some internationally renowned scholars who participated in the activities and initiatives of the latter

    Non-Trivial Dynamics in the FizHugh–Rinzel Model and Non-Homogeneous Oscillatory-Excitable Reaction-Diffusions Systems

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    International audienceThis article focuses on the qualitative analysis of complex dynamics arising in a few mathematical models in neuroscience context. We first discuss the dynamics arising in the three-dimensional FitzHugh–Rinzel (FHR) model and then illustrate those arising in a class of non-homogeneous FitzHugh–Nagumo (Nh-FHN) reaction-diffusion systems. FHR and Nh-FHN models can be used to generate relevant complex dynamics and wave-propagation phenomena in neuroscience context. Such complex dynamics include canards, mixed-mode oscillations (MMOs), Hopf-bifurcations and their spatially extended counterpart. Our article highlights original methods to characterize these complex dynamics and how they emerge in ordinary differential equations and spatially extended models

    The Day-To-Day Practice of MMR and MSI Assessment in Colorectal Adenocarcinoma: What We Know and What We Still Need to Explore

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    Background: The DNA mismatch repair (MMR) system is a highly preserved protein complex recognizing short insertions, short deletions, and single base mismatches during DNA replication and recombination. MMR protein status is identified using immunohistochemistry. Deficit in one or more MMR proteins, configuring deficient MMR status (dMMR), leads to frameshift mutations particularly clustered in microsatellite repeats. Thus, microsatellite instability (MSI) is the epiphenomenon of dMMR. In colorectal cancer (CRC), MMR/MSI status is a biomarker with prognostic and predictive value of resistance to 5-fluorouracil and response to immune checkpoint inhibitor therapy. Summary: In this Review, we describe the challenges the practicing pathologist may face in relation to the assessment of MMR/MSI status and any open issues which still need to be addressed, focusing on pre-analytic issues, pitfalls in the interpretation, and technical aspects of the different assays. Key Messages: The current methods of detecting dMMR/MSI status have been optimized for CRCs, and whether these techniques can be applied to all tumor and specimen types is still not fully understood. Following the Food and Drug Administration (FDA), tissue/site agnostic drug approval of pembrolizumab for advanced/metastatic MSI tumors, MMR/MSI status in gastrointestinal tract is a common request from the oncologist. In this setting, several issues still need to be addressed, including criteria for sample adequacy

    OPTICAL COHERENCE TOMOGRAPHY EVALUATION IN LOCALLY ADVANCED BASAL CELL CARCINOMA DURING SYSTEMIC TREATMENT

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    Background: Basal cell carcinoma (BCC) is the most common cancer in the Caucasian population, and in Italy its incidence is around 100 cases per 100,000 population. It has a multifactorial pathogenesis, and the most important environmental risk factor is ultraviolet radiation (UV) while constitutive activation of Sonic Hedgehog signaling pathway (via mutations in PTCH1 or SMO genes) instead, is by far the most common genetic aberration associated with these tumors. Basal cell carcinoma often has an indolent biological behavior: it has a predominantly local malignancy, rarely metastasizing (0.05-0.1% of cases). In low-risk or superficial BCC, topical or locally destructive therapy is possible, although surgery remains the treatment of choice. Observation: Locally advanced or metastatic basal cell tumors still represent a therapeutic challenge today. Several therapies are currently available in these clinical setting such as radiotherapy and targeted treatments directed against the Hedgehog pathway. With the introduction of Vismodegib and Sonidegib, two hedgehog pathway inhibitors, a response rate of 67% was observed in locally advanced disease and 38% in metastatic disease. We evaluated Sonidegib effectiveness in patients affected by multiple or locally advanced basal cell carcinoma by using non-invasive diagnostic techniques such as videodermoscopy and optical coherence tomography (OCT). Key message: Systemic agent can represent an useful tool in the management of difficult patients and OCT an excellent and easy to use non-invasive technique for the evaluation of non-melanoma skin cancers

    56. Enhancing navigation benchmarking and perception data generation for row-based crops in simulation

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    Service robotics is recently enhancing precision agriculture enabling many automated processes based on efficient autonomous navigation solutions. However, data generation and infield validation campaigns hinder the progress of large-scale autonomous platforms. Simulated environments and deep visual perception are spreading as successful tools to speed up the development of robust navigation with low-cost RGB-D cameras. In this context, the contribution of this work is twofold: a synthetic dataset to train deep semantic segmentation networks together with a collection of virtual scenarios for a fast evaluation of navigation algorithms. Moreover, an automatic parametric approach is developed to explore different field geometries and features. The simulation framework and the dataset have been evaluated by training a deep segmentation network on different crops and benchmarking the resulting navigation
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