Cerebrovascular reactivity and cerebral perfusion of rats with acute liver failure: role of L-glutamine and asymmetric dimethylarginine in L-arginine-induced response

Cerebral blood flow (CBF) is impaired in acute liver failure (ALF), however, the complexity of the underlying mechanisms has often led to inconclusive interpretations. Regulation of CBF depends at least partially on variations in the local brain L‐arginine concentration and/or its metabolic rate. In ALF, other factors, like an increased concentration of asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor and elevated level of L‐glutamine, may contribute to CBF alteration. This study demonstrated strong differences in the reactivity of the middle cerebral arteries and their response to extravascular L‐arginine application between vessels isolated from rats with thioacetamide (TAA)‐induced ALF and control animals. Our results also showed the decrease in the cerebral perfusion in TAA rats measured by arterial spin labeling perfusion magnetic resonance. Subsequently, we aimed to investigate the importance of balance between the concentration of ADMA and L‐arginine in the CBF regulation. In vivo, intraperitoneal L‐arginine administration in TAA rats corrected: (i) decrease in cerebral perfusion, (ii) decrease in brain extracellular L‐arginine/ADMA ratio and (iii) increase in brain L‐glutamine concentration. Our study implicates that impaired vascular tone of cerebral arteries is most likely associated with exposure to high ADMA and L‐glutamine levels resulting in limited availability of L‐arginine and might be responsible for reduced cerebral perfusion observed in AL

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

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

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

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

Performance of the galactomannan antigen detection test in the diagnosis of invasive aspergillosis in children with cancer or undergoing haemopoietic stem cell transplantation

AbstractSerum galactomannan (GM) antigen detection is not recommended for defining invasive aspergillosis (IA) in children undergoing aggressive chemotherapy or allogeneic haemopoietic stem cell transplantation (HSCT). The ability of the GM test to identify IA in children was retrospectively evaluated in a cohort of children. Test performance was evaluated on samples that were collected during 195 periods at risk of IA. Proven IA was diagnosed in seven periods, all with positive GM test results (true positives, 4%), and possible IA was diagnosed in 15 periods, all with negative GM test results (false negatives, 8%). The test result was positive with negative microbiological, histological and clinical features in three periods (false positives, 1%), and in 170 periods it was negative with negative microbiological, histological and clinical features (true negatives, 87%). The sensitivity was 0.32 and the specificity was 0.98; the positive predictive value was 0.70 and the negative predictive value was 0.92. The efficiency of the test was 0.91, the positive likelihood ratio was 18.3, and the negative likelihood ratio was 1.4. The probability of missing an IA because of a negative test result was 0.03. Test performance proved to be better during at-risk periods following chemotherapy than in periods following allogeneic HSCT. The GM assay is useful for identifying periods of IA in children undergoing aggressive chemotherapy or allogeneic HSCT

Precision measurements of Linear Scattering Density using Muon Tomography

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

Thermal effects on electron-phonon interaction in silicon nanostructures

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