169,798 research outputs found
Global wave parametrices on globally hyperbolic spacetimes
No full textIn a recent work the first named author, Levitin and Vassiliev have constructed the wave propagator on a closed Riemannian manifold M as a single oscillatory integral global both in space and in time with a distinguished complex-valued phase function. In this paper, first we give a natural reinterpretation of the underlying algorithmic construction in the language of ultrastatic Lorentzian manifolds. Subsequently we show that the construction carries over to the case of static backgrounds thanks to a suitable reduction to the ultrastatic scenario. Finally we prove that the overall procedure can be generalised to any globally hyperbolic spacetime with compact Cauchy surfaces. As an application, we discuss how, from our procedure, one can recover the local Hadamard expansion which plays a key role in all applications in quantum field theory on curved backgrounds
Hadamard States for Quantum Abelian Duality
No full textAbelian duality is realized naturally by combining differential cohomology and locally covariant quantum field theory. This leads to a (Formula presented.)-algebra of observables, which encompasses the simultaneous discretization of both magnetic and electric fluxes. We discuss the assignment of physically well-behaved states on this algebra and the properties of the associated GNS triple. We show that the algebra of observables factorizes as a suitable tensor product of three (Formula presented.)-algebras: the first factor encodes dynamical information, while the other two capture topological data corresponding to electric and magnetic fluxes. On the former factor and in the case of ultra-static globally hyperbolic spacetimes with compact Cauchy surfaces, we exhibit a state whose two-point correlation function has the same singular structure of a Hadamard state. Specifying suitable counterparts also on the topological factors, we obtain a state for the full theory, ultimately implementing Abelian duality transformations as Hilbert space isomorphisms
Noncontact tonometry in children
No full textA hand-held noncontact tonometer (Pulsair, Keeler Ltd., UK) was tested in 42 children, from 5 months to 12 years of age. At least 1 intraocular pressure (IOP) reading was obtained in all of the 84 eyes studied, whereas with a Goldman applanation tonometer measurements could be obtained in only 26 eyes (14 subjects). Time required for examination with the Pulsair was quite variable and related to age (p less than 0.0001). Compliance in children was reported as "good" in the majority of cases; it was also age-related (p less than 0.005). Although its reliability could not be definitely evaluated, the results of this study indicate that this instrument may be a valuable choice for screening and follow-up purposes in childhood
Conservative management of congenital nasolacrimal duct obstruction
No full textFifty-nine children 1 to 24 months of age with congenital nasolacrimal duct obstruction (CNDO) were treated with local hydrostatic massage and antibiotic eye drops. Children 1 to 12 months of age showed a cure rate of 93.3%; only two of them underwent nasolacrimal probing. Children 13 to 24 months of age had a cure rate of 79.3%, and six underwent probing. The initial probings were successful in both age groups. Fifty-one children (86.4%) were thus spared nasolacrimal probing
Promoting biological phosphorus removal in a full scale pre-denitrification wastewater treatment plant
No full textA survey conducted in Italy revealed that less than 0.5% out of a sample of over 2,000 municipal wastewater treatment plants is equipped with an enhanced biological phosphorus removal process. Conditions promoting biological phosphorus removal have been investigated by monitoring three real plants equipped with, respectively: (A) simultaneous chemical precipitation; (B) enhanced biological removal powered by chemical precipitation; (C) tertiary chemical precipitation with evidence of phosphate accumulating bacteria. An anaerobic compartment revealed essential for the growth of these microorganisms, the readily degradable organic concentration in the influent playing a minor role. Mapping dissolved oxygen and oxidation-reduction potential in different compartments of plant (C) was carried out to understand the reasons why phosphate accumulating bacteria were found even in the absence of anaerobic reactor. Finally, the possibility to exploit the biological phosphorus removal in plant (C), by adjusting the aeration conditions, was explored and an economic analysis showed this to be a preferable approach with respect to the chemical removal of phosphorus
More about the random uncertainty of photometric determination of hemolysis index on the Abbott Alinity c platform
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Il riutilizzo delle vinacce in filiera corta conviene
No full textLo studio, effettuato nelle annate 2008-2009 sul territorio della Franciacorta, ha voluto stimare quale sia il processo migliore, sia in termini economici che ambientali, del riutilizzo delle vinacce. Le alternative utilizzate sono la distillazione, il compostaggio, la digestione anaerobica, la combustione e la pirogasificazione. Le tecniche più interessanti ed efficienti sono risultate: la distillazione perchè molto conveniente, in quanto a fine processo il prodotto conserva un buon potenziale; il compostaggio, risultato invece un metodo poco costoso e di particolare valenza ambientale e la digestione anaerobica, indicata per la produzione di biogas con un’efficienza del 67%, quest’ultima tecnica esige però l’utilizzo di grandi masse
Speech Audio Splicing Detection and Localization Exploiting Reverberation Cues
No full textManipulating speech audio recordings through splicing is a task within everyone's reach. Indeed, it is very easy to collect through social media multiple audio recordings from well-known public figures (e.g., actors, politicians, etc.). These can be cut into smaller excerpts that can be concatenated in order to generate new audio content. As a fake speech from a famous person can be used for fake news spreading and negatively impact on the society, the ability of detecting whether a speech recording has been manipulated is a task of great interest in the forensics community. In this work, we focus on speech audio splicing detection and localization. We leverage the idea that distinct recordings may be acquired in different environments, which are typically characterized by distinctive reverberation cues. Exploiting this property, our method estimates inconsistencies in the reverberation time throughout a speech recording. If reverberation inconsistencies are detected, the audio track is tagged as manipulated and the splicing point time instant is estimated
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