1,335 research outputs found

    Super-resolution provided by the arbitrarily strong superlinearity of the blackbody radiation

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    Blackbody radiation is a fundamental phenomenon in nature, and its explanation by Planck marks a cornerstone in the history of Physics. In this theoretical work, we show that the spectral radiance given by Planck's law is strongly superlinear with temperature, with an arbitrarily large local exponent for decreasing wavelengths. From that scaling analysis, we propose a new concept of super-resolved detection and imaging: if a focused beam of energy is scanned over an object that absorbs and linearly converts that energy into heat, a highly nonlinear thermal radiation response is generated, and its point spread function can be made arbitrarily smaller than the excitation beam focus. Based on a few practical scenarios, we propose to extend the notion of super-resolution beyond its current niche in microscopy to various kinds of excitation beams, a wide range of spatial scales, and a broader diversity of target objects

    Caratteristiche sismostratigrafiche di strutture sedimentarie diagnostiche dicorrenti di fondo nell\u2019off-shore del Golfo di Taranto.

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    L\u2019analisi integrata di dati multibeam e sismici ad altissima risoluzione (Chirp Sub-Bottom), acquisiti in un settore del Golfo di Taranto (Mare Ionio), ha permesso di identificare e classificare strutture sedimentarie diagnostiche di correnti di fondo (conturiti), formatesi nel tardo Quaternario. La classificazione proposta \ue8 basata sia su criteri sismo-stratigrafici che sulla comparazione con strutture analoge documentate da precedenti autori nei bacini oceanici [Faugeres et al., 1999 con rif.]. Nell\u2019area in esame sono stati identificati quattro settori (Alto dell\u2019Amendolara, Bacino di Corigliano, Bacino dell\u2019Amendolara ed Alto di Rossano-Cariati) caratterizzati da morfologia, pendenza e profondit\ue0 differente. Le strutture conturitiche sono state riconosciute prevalentemente nei settori NW e SE dell\u2019alto dell\u2019Amendolara, ad una profondit\ue0 compresa tra 130 m e 400 m e le geometrie interne ed esterne mostrano caratteristiche deposizionali ed erosive. Sono state classificate come sheeted drift le strutture sviluppate subparallelamente al profilo batimetrico, infill drift ed elongated drift le strutture caratterizzate da fosse ben sviluppate ed elementi erosivi quali fosse ed abraded surface. Sono stati osservati inoltre osservati sediment waves nel settore SW dell\u2019alto strutturale. Dall\u2019analisi integrata dei nuovi dati con quelli disponibili in letteratura \ue8 possibile ipotizzare che i fattori che hanno maggiormente influenzato tipologia, distribuzione areale e batimetrica dei depositi conturitici e degli elementi erosivi sono: a) morfologia del fondo marino; b) caratteristiche dei sedimenti (es. tessitura); c) variazione della velocit\ue0 della \u201cLevantine Intermediate Water come conseguenza delle d) variazioni eustatiche. Sono stati inoltre applicati in cascata i modelli bidimensionali CMS- Wave [Lin et al, 2006] per la propagazione dello spettro d\u2019onda, e CMS- Flow [Buttolph et al, 2006] per la circolazione interna, prendendo in considerazione i dati meteo marini forniti dall\u2019ECMWF nel punto di coordinate 39,5\ub0N, 17\ub0E, in modo da valutare le condizioni idrodinamiche in prossimit\ue0 del paraggio in esame. L\u2019integrazione dei dati indicati geologici/geofisici e dei risultati del codice di calcolo numerico ha permesso di ipotizzare un modello di circolazione della corrente \u201cLevantine Intermediate Water\u201d e valutare l\u2019influenza delle morfostrutture sulla circolazione delle acque profonde durante l\u2019ultima fase di abbassamento e stazionamento basso del livello del mare. Bibliografia Buttolph, A.,D., Reed, C.W., Kraus N., Wamsley, T.V., Ono, N., Larson, M.,Camenen, B., Hanson, H. Zundel, A.K., (2006). Two-Dimensional Depth-Averaged Circulation Model CMS-M2D: Version 3.0, Report 2, Sediment Transport and Morphology Change. ERDC/CHL TR-06-9 Vicksburg, MS: U.S. Army Engineer Research and Development Center. Lin, L., H. Mase, F. Yamada, and Z. Demirbilek. (2006). Wave-action balance equation diffraction (WABED) model: Tests of wave diffraction and reflection at inlets. Coastal and Hydraulics Engineering Technical Note ERDC/CHL CHETN-III-73. Vicksburg, MS: U.S. Army Engineer Research and Development Center. Faug\ue8res, J.C., Stow, D.A.V., Imbert, P., Viana, A.R. (1999). Seismic feature diagnostic of contourite drifts. Marine Geology 162, pp. 1-38

    Thermal effects on electron-phonon interaction in silicon nanostructures

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    Raman spectra from silicon nanostructures, recorded using excitation laser power density of 1.0 kW/cm^2, is employed here to reveal the dominance of thermal effects at temperatures higher than the room temperature. Room temperature Raman spectrum shows only phonon confinement and Fano effects. Raman spectra recorded at higher temperatures show increase in FWHM and decrease in asymmetry ratio with respect to its room temperature counterpart. Experimental Raman scattering data are analyzed successfully using theoretical Raman line-shape generated by incorporating the temperature dependence of phonon dispersion relation. Experimental and theoretical temperature dependent Raman spectra are in good agreement. Although quantum confinement and Fano effects persists, heating effects start dominating at higher temperatures than room tempaerature.Comment: 9 Pages, 3 Figures and 1 Tabl

    Precision measurements of Linear Scattering Density using Muon Tomography

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    We demonstrate that muon tomography can be used to precisely measure the properties of various materials. The materials which have been considered have been extracted from an experimental blast furnace, including carbon (coke) and iron oxides, for which measurements of the linear scattering density relative to the mass density have been performed with an absolute precision of 10%. We report the procedures that are used in order to obtain such precision, and a discussion is presented to address the expected performance of the technique when applied to heavier materials. The results we obtain do not depend on the specific type of material considered and therefore they can be extended to any application.Comment: 16 pages, 4 figure

    Shear-Mediated Dilation of the Internal Carotid Artery Occurs Independent of Hypercapnia.

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    Evidence for shear stress as a regulator of carotid artery dilation in response to increased arterial carbon dioxide was recently demonstrated in humans during sustained elevations in CO2 (hypercapnia); however, the relative contributions of CO2 and shear stress to this response remains unclear. We examined the hypothesis that, following a 30-second transient increase in arterial CO2 tension and consequent increase in internal carotid artery shear stress, internal carotid artery diameter would increase, indicating shear-mediated dilation, in the absence of concurrent hypercapnia. In 27 healthy participants the partial pressures of end-tidal O2 and CO2, ventilation (pneumotachography), blood pressure (finger-photoplethysmography), heart-rate (electrocardiogram), internal carotid artery flow, diameter and shear stress (high resolution duplex ultrasound) and middle cerebral artery blood velocity (transcranial Doppler) were measured during 4-minute steady state and transient 30-second hypercapnic tests (both +9mmHg CO2). Internal carotid artery dilation was lower in the transient, compared to the steady state hypercapnia (3.3±1.9% vs. 5.3±2.9%, respectively; P<0.03). Increases in internal carotid artery shear stress preceded increases in diameter in both the transient (time: 16.8±13.2s vs. 59.4±60.3s; P<0.01) and steady state (time: 18.2±14.2s vs. 110.3±79.6s; P<0.01) tests. Internal carotid artery dilation was positively correlated with shear rate area under the curve in the transient (r(2)=0.44; P<0.01), but not steady state (r(2)=0.02; P=0.53) trial. Collectively, these results suggest that hypercapnia induces shear-mediated dilation of the internal carotid artery in humans. This study further promotes the application and development of hypercapnia as a clinical strategy for the assessment of cerebrovascular vasodilatory function and health in humans

    Photoelectric Emission from Interstellar Dust: Grain Charging and Gas Heating

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    We model the photoelectric emission from and charging of interstellar dust and obtain photoelectric gas heating efficiencies as a function of grain size and the relevant ambient conditions. Using realistic grain size distributions, we evaluate the net gas heating rate for various interstellar environments, and find less heating for dense regions characterized by R_V=5.5 than for diffuse regions with R_V=3.1. We provide fitting functions which reproduce our numerical results for photoelectric heating and recombination cooling for a wide range of interstellar conditions. In a separate paper we will examine the implications of these results for the thermal structure of the interstellar medium. Finally, we investigate the potential importance of photoelectric heating in H II regions, including the warm ionized medium. We find that photoelectric heating could be comparable to or exceed heating due to photoionization of H for high ratios of the radiation intensity to the gas density. We also find that photoelectric heating by dust can account for the observed variation of temperature with distance from the galactic midplane in the warm ionized medium.Comment: 50 pages, including 18 figures; corrected title and abstract field

    Cidofovir for BK Virus-Associated Hemorrhagic Cystitis: A Retrospective Study

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    Background.BK virus-associated hemorrhagic cystitis (BKV-HC) is a severe complication after allogeneic hematopoietic stem cell transplantation (HSCT), but antiviral treatment for this condition has not been evaluated. Methods.We conducted a retrospective survey on the safety and outcome of cidofovir treatment for patients with BKV-HC in centers affiliated with the European Group for Blood and Marrow Transplantation. Results.From 1 April 2004 to 31 December 2007, 62 patients received a diagnosis of BKV-HC after a median interval of 35 days after HSCT (range, 3-577 days). Fifty-seven patients (92%) received intravenous cidofovir, whereas 5 patients received cidofovir intravesically. Complete response (CR) was recorded in 38 (67%) of 57 patients with HC treated with intravenous cidofovir, whereas partial response (PR) was documented in 7 patients (12%). CR was documented in 3 patients and PR in 1 patient with HC treated with intravesical cidofovir. A reduction of 1-3 logs in BKV load was documented in 8 of the 10 patients achieving CR. Mild-to-moderate toxic effects were recorded in 18 of 57 patients who received intravenous cidofovir administration. In a multivariate analysis, the factors significantly associated with response to cidofovir were the stem cell source (P=.01) and the use of total body irradiation (P=.03). After a median follow-up of 287 days, overall survival and total treatment-related mortality rates were 63% and 40% for patients achieving CR, compared with 14% and 72% for patients with PR or no response to cidofovir, respectively (P<.001 and P=.001, respectively). Conclusions.Cidofovir may be a potentially effective therapy for BKV-HC, but evidence supporting its use requires randomized controlled trial

    Coastal boulder production controlled by columnar joints of ignimbrite and extreme waves: insights from the high-energy coast of Pantelleria Island (Sicily Channel, Mediterranean Sea)

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    We examined the relationship between coastal boulder production and the volcanic rock features on the high-energy rocky coast of Pantelleria Island (Sicily Channel, Mediterranean Sea). We used geological data for 125 boulders and 21 rupture surfaces, integrated with fracture analysis, radiocarbon dating, numerical hydrodynamic analysis, and hindcast numerical model for wave characterization. The boulder field consists of isolated and grouped blocks detected along the shore platform and on the cliff top of Punta Sidere (northwestern coast of Pantelleria). Boulder production occurred through two mechanisms: (1) boulders were quarried from the platform edge of the low coast and cliff top as suggested by the same lithology of boulders and outcropping rocks, and by the similar shape of the boulders and rupture surfaces carved out into the rocky platform; (2) waves eroded the cliff foot, forming a notch, and boulders detached from cliff face and fell down to the shore platform. The morphometric analysis of the characteristics of boulders and outcropping rocks demonstrates that the columnar fractures controlled the boulders' polygonal surfaces and size. Whereas, the thickness of horizontal planes within the ignimbrite controlled the boulders' thickness. The numerical hydrodynamic analysis indicates that the quarrying, transport and deposition of boulders were mainly the result of storm waves up to 8&nbsp;m high. The storm events occurred at different times, even recently, as suggested by two radiocarbon dating of biogenic encrustations collected from the boulders' surface and the presence of wood and plastic embedded within the boulder deposits

    Hemiptera records from Lake Spechtensee and from Southern Styria (Austria)

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    Hemiptera records gained in July 2015 in course of the 7th European Hemiptera Congress in Styria are presented. In total, 144 Auchenorrhyncha, 143 Heteroptera, 13 Psylloidea and 2 Aphididae species were collected. Ribautodelphax imitans (Delphacidae), Eurhadina saageri (Cicadellidae), Notonecta maculata (Notonectidae), Notonecta meridionalis (Notonectidae) and Polymerus cognatus (Miridae) are new records for Styria
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