6,677 research outputs found

    Phase shifts of synchronized oscillators and the systolic/diastolic blood pressure relation

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    We study the phase-synchronization properties of systolic and diastolic arterial pressure in healthy subjects. We find that delays in the oscillatory components of the time series depend on the frequency bands that are considered, in particular we find a change of sign in the phase shift going from the Very Low Frequency band to the High Frequency band. This behavior should reflect a collective behavior of a system of nonlinear interacting elementary oscillators. We prove that some models describing such systems, e.g. the Winfree and the Kuramoto models offer a clue to this phenomenon. For these theoretical models there is a linear relationship between phase shifts and the difference of natural frequencies of oscillators and a change of sign in the phase shift naturally emerges.Comment: 8 figures, 9 page

    Ultrafast Electrochemical Self-Doping of Anodic Titanium Dioxide Nanotubes for Enhanced Electroanalytical and Photocatalytic Performance

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    This study explores an ultrarapid electrochemical self-doping procedure applied to anodic titanium dioxide (TiO2) nanotube arrays in an alkaline solution to boost their performance for electroanalytical and photocatalytic applications. The electrochemical self-doping process (i.e., the creation of surface Ti3+ states by applying a negative potential) is recently emerging as a simpler and cleaner way to improve the electronic properties of TiO2 compared to traditional chemical and high-temperature doping strategies. Here, self-doping was carried out through varying voltages and treatment times to identify the most performing materials without compromising their structural stability. Interestingly, cyclic voltammetry characterization revealed that undoped TiO2 shows negligible activity, whereas all self-doped materials demonstrate their suitability as electrode materials: an outstandingly short 10 s self-doping treatment leads to the highest electrochemical activity. The electrochemical detection of hydrogen peroxide was assessed as well, demonstrating a good sensitivity and a linear detection range of 3–200 µM. Additionally, the self-doped TiO2 nanotubes exhibited an enhanced photocatalytic activity compared to the untreated substrate: the degradation potential of methylene blue under UV light exposure increased by 25% in comparison to undoped materials. Overall, this study highlights the potential of ultrafast electrochemical self-doping to unleash and improve TiO2 nanotubes performances for electroanalytical and photocatalytic applications

    Expanded Endoscopic Approach for Anterior Skull Base Tumors: Experience of a Multidisciplinary Skull Base Team

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    Abstract: The aim of this study is to describe the experience of a multidisciplinary skull base team with transnasal endoscopic surgery for anterior cranial base tumors. A retrospective chart review was conducted on patients who underwent an exclusive expanded transnasal approach to the anterior skull base in the period from December 2014 to November 2015. Data on patient demographics, tumor characteristics, surgical information, imaging, and postoperative complications were collected and analyzed. From a total of 120 patients with skull base diseases managed by the skull base team, 36 were admitted to this study. The overall complication rate in this series was 16.7%, gross total resection was achieved in 32 cases (88.9%) and postoperative CSF leakage occurred in 5 cases (13.9%). Our preliminary results confirm that an exclusive endoscopic transnasal approach to the anterior cranial base

    Cost-effectiveness of intravitreal therapy with both anti-VEGF and Dexamethasone implant in patients with Diabetic Macular Edema

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    Purpose: The aim of this study was to evaluate the cost-effectiveness of intravitreal therapy (IVT) with both anti-VEGF and Dexamethasone implant in patients with Diabetic Macular Edema (DME) during two years’ follow-up. Methods: A retrospective review of 191 patients (382 eyes) with type I and II diabetes and DME was performed. Pre-IVT and final best correct visual acuity (BCVA), central macular thickness (CMT), intraocular pressure (IOP), number and type of IVT,number of examinations, and fluorescein angiography were assessed. Based on surgery procedure other than IVT, patients were divided into 5 groups. To avoid bias, we analysed only patients who had undergone cataract surgery before (group 1) or during enrolment (group 2). Results: 41 eyes from Group 1 and 48 eyes from group 2 were evaluated. Median BCVA ranged between 20/80 and 20/63 Snellen (P = 0.008) in Group 1 and from 20/63 to 20/40 Snellen (P = 0.0035) in Group 2, while improvement up to 1 Snellen line was observed in 58.5 and 68.75% of eyes in Group 1 and 2, respectively.In terms of median CMT, a statistically reduction (P = 0.0007) was found in Group 2 (-85 μm), whereas no statistical differences were found in Group 1. The two groups showed no statistically significant difference in median IOP. The estimated cost per eye was €7803 in Group 1 and €8988 Group 2, whereas the mean cost per patient was €15190 and €16580 in Group 1 and 2, respectively. Analysis between groups did not show any statistical difference in the considered parameters. Conclusions: In this study, despite the high treatment cost, vision improvement in DME patients undergoing IVT was disappointing. Our results emphasise the need for a better understanding of the cost-effectiveness of DME treatmen

    Small bowel transplantation for diffuse intestinal angiomatosis

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    Intestinal angiomatosis is a very rare phenomenon producing lower gastrointestinal bleeding. Its most frequent causes are diverticula, congenital arteriovenous malformation, acquired angiodysplasia, ischemia, inflammation, ulceration, benign or malignant tumours and iatrogenic injury. In this paper, the case of a 48-year-old white man is reported
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