2,877 research outputs found

    Torsion free groups with indecomposable holonomy group I

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    We study the torsion free generalized crystallographic groups with the indecomposable holonomy group which is isomorphic to either a cyclic group of order ps{p^s} or a direct product of two cyclic groups of order p{p}.Comment: 22 pages, AMS-Te

    The two-component giant radio halo in the galaxy cluster Abell 2142

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    We report on a spectral study at radio frequencies of the giant radio halo in A2142 (z=0.0909), which we performed to explore its nature and origin. A2142 is not a major merger and the presence of a giant radio halo is somewhat surprising. We performed deep radio observations with the GMRT at 608 MHz, 322 MHz, and 234 MHz and with the VLA in the 1-2 GHz band. We obtained high-quality images at all frequencies in a wide range of resolutions. The radio halo is well detected at all frequencies and extends out to the most distant cold front in A2142. We studied the spectral index in two regions: the central part of the halo and a second region in the direction of the most distant south-eastern cold front, selected to follow the bright part of the halo and X-ray emission. We complemented our observations with a preliminary LOFAR image at 118 MHz and with the re-analysis of archival VLA data at 1.4 GHz. The two components of the radio halo show different observational properties. The central brightest part has higher surface brightess and a spectrum whose steepness is similar to those of the known radio halos, i.e. α118 MHz1.78 GHz=1.33±0.08\alpha^{\rm 1.78~GHz}_{\rm 118~MHz}=1.33\pm 0.08. The ridge, which fades into the larger scale emission, is broader in size and has considerably lower surface brightess and a moderately steeper spectrum, i.e. α118 MHz1.78 GHz1.5\alpha^{\rm 1.78~GHz}_{\rm 118~MHz}\sim 1.5. We propose that the brightest part of the radio halo is powered by the central sloshing in A2142, similar to what has been suggested for mini-halos, or by secondary electrons generated by hadronic collisions in the ICM. On the other hand, the steeper ridge may probe particle re-acceleration by turbulence generated either by stirring the gas and magnetic fields on a larger scale or by less energetic mechanisms, such as continuous infall of galaxy groups or an off-axis merger.Comment: 18 pages, 10 figures, 4 tables - A&A, accepte

    Urban policies and planning approaches for a safer and climate friendlier mobility in cities: Strategies, initiatives and some analysis

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    How can urban policies and planning approaches help in achieving a safer mobility and carbon reduction in the transport sector? The attention of planners and policy makers towards the promotion of sustainability and reduction of environmental impacts has grown in recent years. This paper investigates the role that Urban Planning plays in the long term towards a safer and climate friendlier mobility, highlighting the need for integrated approaches gathering spatial planning and mobility management. After a review of several urban policies and planning strategies, initiatives, and approaches, mainly based on the urban scale, the paper presents an urban regeneration case study leading to an increase of pedestrian accessibility at the neighborhood level. This can be seen as a support tool to foster sustainable, safe, and climate friendly mobility in cities. The results of the performed analysis show a dependency of accessibility from two different factors: the distribution of services and the capillarity of the soft mobility network, which can contribute to creating a more walkable space

    Tympanic cholesterol granuloma and exclusive endoscopic approach

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    Objective: Background: Case Report: Conclusions: Unusual or unexpected effect of treatment Cholesterol granuloma is a histological entity containing cholesterol crystals surrounded by foreign-body giant cells and chronic inflammation. Tympanic cholesterol granuloma is a rare disease, while petrous bone cholesterol granuloma is more common. Surgery consists of elective management in most cases of CGs. There are several types of surgery described to treat cholesterol granuloma; however, a case treated by primary endoscopic ear surgery has not yet been described. The aim of this case report is to present the endoscopic characteristics of cholesterol granulomas and show how endoscopic ear surgery is possible in isolated and selected cases with this pathology. We report the case of a 65-year-old patient affected by a cholesterol granuloma of the middle ear, with progressive hearing impairment and fullness of the left ear. The granuloma was diagnosed via medical imaging using magnetic resonance imaging, which identified the typical high signal intensity in T1-and T2-weighted images. In this case, cholesterol granuloma was limited to the epitympanic and mesotympanic regions. For small cholesterol granulomas confined to the middle ear, a canal wall-up or wall-down tympanoplasty plus ventilation tube insertion are usually performed. In this case, primary endoscopic surgery was performed under general anaesthesia to remove the presumed cholesterol granuloma. It was completely removed by this approach, without facial nerve injuries or postoperative complications. The patient had no disease recurrence at clinical and radiological investigation at 1-year follow-up. An exclusive endoscopic approach to remove cholesterol granuloma is feasible. However, it should only be performed in selected cases

    Evaluation of a clinical tool for early etiology identification in status epilepticus.

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    OBJECTIVES: Because early etiologic identification is critical to select appropriate specific status epilepticus (SE) management, we aim to validate a clinical tool we developed that uses history and readily available investigations to guide prompt etiologic assessment. METHODS: This prospective multicenter study included all adult patients treated for SE of all but anoxic causes from four academic centers. The proposed tool is designed as a checklist covering frequent precipitating factors for SE. The study team completed the checklist at the time the patient was identified by electroencephalography (EEG) request. Only information available in the emergency department or at the time of in-hospital SE identification was used. Concordance between the etiology indicated by the tool and the determined etiology at hospital discharge was analyzed, together with interrater agreement. RESULTS: Two hundred twelve patients were included. Concordance between the etiology hypothesis generated using the tool and the finally determined etiology was 88.7% (95% confidence interval (CI) 86.4-89.8) (κ = 0.88). Interrater agreement was 83.3% (95% CI 80.4-96) (κ = 0.81). SIGNIFICANCE: This tool is valid and reliable for identification early the etiology of an SE. Physicians managing patients in SE may benefit from using it to identify promptly the underlying etiology, thus facilitating selection of the appropriate treatment

    Dark matter-baryons separation at the lowest mass scale: the Bullet Group

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    We report on the X-ray observation of a strong lensing selected group, SL2S J08544-0121, with a total mass of 2.4±0.6×10142.4 \pm 0.6 \times 10^{14} M\rm{M_\odot} which revealed a separation of 124±20124\pm20 kpc between the X-ray emitting collisional gas and the collisionless galaxies and dark matter (DM), traced by strong lensing. This source allows to put an order of magnitude estimate to the upper limit to the interaction cross section of DM of 10 cm2^2 g1^{-1}. It is the lowest mass object found to date showing a DM-baryons separation and it reveals that the detection of bullet-like objects is not rare and confined to mergers of massive objects opening the possibility of a statistical detection of DM-baryons separation with future surveys.Comment: 5 pages, 3 figures. Accepted for publication in MNRAS Letters. Typos correcte

    Artificial intelligence weights the importance of factors predicting complete cytoreduction at secondary cytoreductive surgery for recurrent ovarian cancer

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    Objective: Accumulating evidence support that complete cytoreduction (CC) at the time of secondary cytoreductive surgery (SCS) improves survival in patients affected by recurrent ovarian cancer (ROC). Here, we aimed to determine whether artificial intelligence (AI) might be useful in weighting the importance of clinical variables predicting CC and survival. Methods: This is a retrospective study evaluating 194 patients having SCS for ROC. Using artificial neuronal network (ANN) analysis was estimated the importance of different variables, used in predicting CC and survival. ANN simulates a biological neuronal system. Like neurons, ANN acquires knowledge through a learning-phase process and allows weighting the importance of covariates, thus establishing how much a variable influences a multifactor phenomenon. Results: Overall, 82.9% of patients had CC at the time of SCS. Using ANN, we observed that the 3 main factors driving the ability of achieve CC included: disease-free interval (DFI) (importance: 0.231), retroperitoneal recurrence (importance: 0.178), residual disease at primary surgical treatment (importance: 0.138), and International Federation of Gynecology and Obstetrics (FIGO) stage at presentation (importance: 0.088). Looking at connections between different covariates and overall survival (OS), we observed that DFI is the most important variable influencing OS (importance: 0.306). Other important variables included: CC (importance: 0.217), and FIGO stage at presentation (importance: 0.100). Conclusion: According to our results, DFI should be considered as the most important factor predicting both CC and OS. Further studies are needed to estimate the clinical utility of AI in providing help in decision making process

    Citicoline in ophthalmological neurodegenerative disease: A comprehensive review

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    Cytidine 5'-diphosphocholine has been widely studied in systemic neurodegenerative diseases, like Alzheimer's disease, Parkinson's disease, and brain ischemia. The rationale for the use of citicoline in ophthalmological neurodegenerative diseases, including glaucoma, anterior ischemic optic neuropathy, and diabetic retinopathy, is founded on its multifactorial mechanism of action and the involvement in several metabolic pathways, including phospholipid homeostasis, mitochondrial dynamics, as well as cholinergic and dopaminergic transmission, all being involved in the complexity of the visual transmission. This narrative review is aimed at reporting both pre-clinical data regarding the involvement of citicoline in such metabolic pathways (including new insights about its role in the intracellular proteostasis through an interaction with the proteasome) and its effects on clinical psychophysical, electrophysiological, and morphological outcomes following its use in ophthalmological neurodegenerative diseases (including the results of the most recent prospective randomized clinical trials)

    Facial nerve dehiscence and cholesteatoma: a comparison between decades

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    OBJECTIVES: To evaluate the incidence of facial canal dehiscence (FCD) and other intraoperative findings over the last 20 years as well as correlation with the Japanese Otological Society/European Academy of Otology and Neurotology classification in patients with cholesteatoma. MATERIALS and METHODS: A total of 469 patients operated from 1998 to 2018 were selected and divided into 2 groups of 10 years each. RESULTS: Dehiscence was significantly higher in patients with a history of pathology longer than 5 years (22.7%). Higher values were observed in revision surgery, 44.4% in the first period and 41.7% in the second. The tympanic segment was the one most frequently involved, affecting 92% of patients in the first period and 97% of patients in the second. Dehiscence occurred significantly more often in patients with a semicircular canal fistula, 14.8% in the first decade and 8.8% in the second. The incidence of FCD was significantly higher in patients with primary cholesteatoma (especially in those with combined pars tensa-flaccida) than in those with a secondary acquired one, 31.5% vs 7.4% in the first period, 21.1% vs 7.4% in the second, and in those with a stage III disease, 42% in the first period, 33.3% in the second. CONCLUSION: Patients with a shorter history of cholesteatoma as well as those not previously operated had a lower incidence of FCD. The tym-panic tract of the facial nerve remains the most frequent site of dehiscence, while the association between dehiscence and fistula of the semicircular canal remains strong. Patients with combined pars tensa-pars flaccida and stage III cholesteatoma have a higher incidence of FCD
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