328 research outputs found

    The Method of Images in Cosmology

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    31 pages, 18 figures31 pages, 18 figuresWe apply the method of images to the exact initial data for cosmological models that contain a number of regularly arranged discrete masses. This allows us to join cosmological regions together by throats, and to construct wormholes in the initial data. These wormholes allow for the removal of the asymptotically flat "flange" regions that would otherwise exist on the far side of black holes. The method of images also provides us with a way to investigate the definition of mass is cosmology, and the cosmological consequences of the gravitational interaction energies between massive objects. We find evidence that the interaction energies within clusters of massive objects do indeed appear to contribute to the total energy budget in the cosmological regions of the space-time

    The role of atopy in otitis media with effusion among primary school children: audiological investigation

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    Objective of this study is to value the role of atopy in otitis media with effusion (OME) in children attending primary school in Western Sicily focusing on the audiological characteristics among atopic and non atopic subjects suffering from OME. 310 children (5-6 years old) were screened by skin tests and divided into atopics (G1) and non atopics (G2). The samples were evaluated for OME by pneumatic otoscopy, tympanogram and acoustic reflex tests. The parameters considered were: documented persistent middle ear effusion by otoscopic examination for a minimum of 3 months; presence of B or C tympanogram; absence of ipsilateral acoustic reflex and a conductive hearing loss greater than 25 dB at any one of the frequencies from 250 Hz through 4 kHz. 56 children (18.06%) resulted atopics while 254 were non atopics. OME was identified in 24 atopic children and in 16 non atopic children for a total number of 40 children; the overall prevalence rate was 12.9% (42.85% for G1 and 6.30% for G2). OME was bilateral in 28 children (70%), with a significative difference between G1 (79.17%) and G2 (56.25%). The prevalence of B tympanogram was 70.59%, corresponding to 79.07% for G1 and 56% for G2. The mean air conduction pure tone was respectively 31.97 dB for G1 and 29.8 dB for G2. The prevalence value of OME in atopics children, also supported by the higher predominance of bilaterality, B tympanogram and hearing loss among this group, could suggest the important role of allergy in the pathogenesis of OME

    Cavernous haemangioma of the external auditory canal: clinical case and review of the literature

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    Although benign vascular lesions are frequent in the head and the neck region, clinical evidence of cavernous haemangioma of the external auditory canal is extremely rare; when present, the lesion invades the middle ear space. Herein, a rare case of a soft mass filling the external auditory canal, not involving the tympanic membrane, in a symptomatic 59-year-old male is described. Clinical and audiological characteristics, imaging studies and surgical treatment with histological evaluation are reported, which led to a diagnosis of a cavernous haemangioma. This is only the seventh case described in the literature, to date, not involving the tympanic membrane and the middle ear space. In addition, a review has been made of the relevant literature with respect to epidemiology, presentation, evaluation, pathology, and management options for haemangiomas arising in the external auditory canal

    Reduction of multidrug-resistant (Mdr) bacterial infections during the covid-19 pandemic: a retrospective study

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    Multidrug-resistant (MDR) organisms are emerging as some of the main healthcare prob-lems worldwide. During the COVID-19 pandemic, several Infection Prevention and Control (IPC) measures have been adopted to reduce nosocomial microorganism transmission. We performed a case‚Äďcontrol study to identify if the incidence of MDR bacterial infections while using pandemic-related preventive measures is lower than in previous years. From 2017 to 2020, we monitored hospital discharges over a four-month period (P #) (1 March to 30 June) in St. Andrea Hospital, Rome. In total, we reported 1617 discharges. Pearson‚Äôs chi-squared test was used to identify significant differences. A value of p ‚ȧ 0.05 was considered statistically significant. A significant reduction in the incidence of total MDR bacterial infections was observed during the pandemic compared to in prepandemic years (p < 0.05). We also found a significantly higher incidence of MDR bacterial infections in COVID-19 departments compared with other medical departments (29% and 19%, respectively), with extended-spectrum ő≤-lactamase Klebsiella pneumoniae as the pathogens presenting the highest increase. This study demonstrates that maintaining a high level of preventive measures could help tackle an important health problem such as that of the spread of MDR bacteria

    Leg ulcer and osteomyelitis due to methicillin-susceptible Staphylococcus aureus infection after fracture repair treatment: a case highlighting the potential role of prostaglandin E‚āĀ vasodilator

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    Prostaglandins appear to reduce biofilm formation and chronicization of infections, and stimulate a rapid and effective clearance of infecting micro-organisms. We report a case of recovery from methicillin-susceptible Staphylococcus aureus (MSSA) osteomyelitis after multidisciplinary management with antibiotics, anti-thrombotics and prostaglandin E1 (PGE1) vasodilator, in a patient with tibial plateau fracture repaired with internal fixation devices. A 47-year-old HIV-negative male with chronic ulcer on the proximal third of the left leg was admitted to the Orthopaedic Unit of the Orestano Clinic in Palermo, Italy, for suspected osteomyelitis. A biopsy of the skin ulcer and blood cultures were performed and resulted positive for MSSA. Labelled leukocyte scintigraphy confirmed osteomyelitis. No clinical improvement was observed after combined antibiotic treatment with rifampicin plus trimethoprim-sulfamethoxazole. The patient underwent a 4-day therapeutic cycle: PGE1 (alprostadil 60 mg/day IV) combined with nadroparin calcium plus gentamicin, followed by treatment with aminaftone plus sulodexide plus levofloxacin. At discharge, the patient's painful symptoms had completely resolved and the ulcer had cicatrized; recovery from osteomyelitis was confirmed by scintigraphy. This treatment protocol including PGE1 may result in a significant improvement in quality of life and functional status of patients with a reduction in direct and indirect costs and economic benefit for the National Health Service

    On the Possibility of Quantum Gravity Effects at Astrophysical Scales

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    The nonperturbative renormalization group flow of Quantum Einstein Gravity (QEG) is reviewed. It is argued that at large distances there could be strong renormalization effects, including a scale dependence of Newton's constant, which mimic the presence of dark matter at galactic and cosmological scales.Comment: LaTeX, 18 pages, 4 figures. Invited contribution to the Int. J. Mod. Phys. D special issue on dark matter and dark energ

    Persistent black holes in bouncing cosmologies

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    In this paper we explore the idea that black holes can persist in a universe that collapses to a big crunch and then bounces into a new phase of expansion. We use a scalar field to model the matter content of such a universe {near the time} of the bounce, and look for solutions that represent a network of black holes within a dynamical cosmology. We find exact solutions to Einstein's constraint equations that provide the geometry of space at the minimum of expansion and that can be used as initial data for the evolution of hyperspherical cosmologies. These solutions illustrate that there exist models in which multiple distinct black holes can persist through a bounce, and allow for concrete computations of quantities such as the black hole filling factor. We then consider solutions in flat cosmologies, as well as in higher-dimensional spaces (with up to nine spatial dimensions). We derive conditions for the black holes to remain distinct (i.e. avoid merging) and hence persist into the new expansion phase. Some potentially interesting consequences of these models are also discussed.Comment: 37 pages, 16 figure
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