1,610 research outputs found

    Intermittency and scaling laws for wall bounded turbulence

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    Well defined scaling laws clearly appear in wall bounded turbulence, even very close to the wall, where a distinct violation of the refined Kolmogorov similarity hypothesis (RKSH) occurs together with the simultaneous persistence of scaling laws. A new form of RKSH for the wall region is here proposed in terms of the structure functions of order two which, in physical terms, confirms the prevailing role of the momentum transfer towards the wall in the near wall dynamics.Comment: 10 pages, 5 figure

    Scaling properties in the production range of shear dominated flows

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    Recent developments in turbulence are focused on the effect of large scale anisotropy on the small scale statistics of velocity increments. According to Kolmogorov, isotropy is recovered in the large Reynolds number limit as the scale is reduced and, in the so-called inertial range, universal features -namely the scaling exponents of structure functions - emerge clearly. However this picture is violated in a number of cases, typically in the high shear region of wall bounded flows. The common opinion ascribes this effect to the contamination of the inertial range by the larger anisotropic scales, i.e. the residual anisotropy is assumed as a weak perturbation of an otherwise isotropic dynamics. In this case, given the rotational invariance of the Navier-Stokes equations, the isotropic component of the structure functions keeps the same exponents of isotropic turbulence. This kind of reasoning fails when the anisotropic effects are strong as in the production range of shear dominated flows. This regime is analyzed here by means of both numerical and experimental data for a homogeneous shear flow. A well defined scaling behavior is found to exist, with exponents which differ substantially from those of classical isotropic turbulence. Contrary to what predicted by the perturbation approach, such a deep alteration concerns the isotropic sector itself. The general validity of these results is discussed in the context of turbulence near solid walls, where more appropriate closure models for the coarse grained Navier-Stokes equations would be advisable.Comment: 4 pages, 4 figure

    Increased activity of cell surface peptidases in HeLa cells undergoing UV-induced apoptosis is not mediated by caspase 3

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    We have previously shown that in HeLa cells treated with a variety of agents there is an increase in cell surface peptidase (CSP) activity in those cells undergoing apoptosis. The increase in CSP activity observed in UVB-irradiated cells undergoing apoptosis was unaffected when the cultures were treated with the aminopeptidase inhibitor bestatin, and matrix metalloprotease inhibitor BB3103, but greatly enhanced when treated with the caspase 3 inhibitor-DEVD, and reduced in the presence of the poly(ADP-ribose) polymerase (PARP) inhibitor-3-aminobenzamide (3AB). Neither 3AB nor DEVD had an effect on the gross morphology of the apoptotic cells observed under electron microscopy, nor did they have an effect on phosphatidylserine eversion on the cell membrane, or that of PARP cleavage. All the agents except for DEVD had no effect on the level of caspase 3 activity in the cells. The results suggest that other caspases may cleave PARP in these cells. Both 3AB and DEVD treatment reduced the level of actin cleavage seen in the apoptotic cells. The increase in CSP activity observed in cells undergoing UVB-induced apoptosis appears to involve PARP but not caspase 3

    Knee stability, athletic performance and sport-specific tasks in non-professional soccer players after ACL reconstruction: comparing trans-tibial and antero-medial portal techniques.

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    Background: a wrong position of bone tunnels, in particular on the femur, is one of the most frequent causes of a failed anterior cruciate ligament (ACL) reconstruct ion. Several studies demonstrated that drilling the femoral tunnel through the antero-medial portal (AMP) allows a more anatomical placement on the lateral femoral condyle and higher knee stability, compared to trans-tibial (TT) technique. The aim of this study was to retrospectively evaluate two groups of soccer players operated on for ACL reconstruction according to either one of these two techniques. Methods: two groups of non-professional soccer players operated on for a single bundle ACL reconstruction with hamstrings autograft using either a TT (20 patients) or an AMP (23 patients) technique were retrospectively evaluated with KT- 1000 arthrometer, manual pivot shift test, isokinetic test, the incremental treadmill-running test, athletic and sport specific tasks, and knee scores (IKDC, Lysholm and KOOS). Results: the AMP group showed better results at pivot shift test and KOOS, but lower flexion angles at single leg squat test. There were no differences in all the other considered outcomes. Conclusions: the better rotational stability of the knee achieved in AMP group did not lead to significantly better clinical and functional results in our patients. Level of evidence III. Treatment study: Case-control study

    QualitĂ  pomologica e sensoriale di 10 varietĂ  di mango (Mangifera indica L.) coltivate in Sicilia

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    Il mango (Mangifera indica L.) è una pianta arborea originaria della regione Indo-Burmese, che appartiene botanicamente alla famiglia delle Anacardiaceae, principalmente coltivata nei paesi a clima tropicale e subtropicale ed oggi, complice il cambiamento climatico, diffusa anche nel bacino del mediterraneo. In Italia il mango viene coltivato solo in Sicilia dove areali della costiera tirrenica hanno fatto registrare produzioni di pregio e una crescente diffusione di nuove cultivar provenienti dai luoghi di origine. Limiti vegetazionali piuttosto stretti, soprattutto in termini di minime termiche stagionali, hanno, in passato, causato l’insuccesso di numerosi nuovi impianti basati sull’introduzione di varietà inedite negli areali a clima mediterraneo-subtropicale come in Sicilia. Per evitare il verificarsi di tali situazioni occorre, quindi, valutare con attenzione il comportamento vegeto-produttivo delle nuove introduzioni varietali. Il presente lavoro ha avuto come obiettivo quello di valutare l’adattamento di 10 cultivar di mango mettendo in relazione gli stadi fenologici con gli andamenti termici stagionali utilizzando la scala BBCH (Biologische Bundesantalt, Bundessortenamt und Chemische Industrie) e valutando la qualità fisico-chimica dei frutti. Per ciascun frutto delle 10 varietà in esame sono state analizzate le seguenti caratteristiche: peso del frutto, diametro trasversale del frutto, diametro longitudinale del frutto, consistenza della polpa, peso della polpa, peso della buccia, peso del seme, diametro trasversale del seme, diametro longitudinale del seme. Del succo di ogni frutto sono stati analizzati il contenuto in solidi solubili e l’acidità titolabile. Le prove sono state svolte presso l’azienda Cupitur sita in Caronia Marina, provincia di Messina. Le cv prese in esame sono state: Glenn, Osteen, Maya, Nam Dok Mai, Irwin, Calypso, Valencia Pride, Keitt, Kent e Tommt Atkyns. La correlazione tra stadi fenologici e temperatura nonché il confronto con i risultati ottenuti in ambienti vocati indicano che, seppur con alcuni limiti legati all’inverno, le aree della costa tirrenica della Sicilia, dove queste varietà sono state coltivate, risultano un ambiente climaticamente idoneo per il corretto evolversi delle fasi vegetative e produttive e l’ottenimento di frutti dalle interessanti qualità organolettiche. Tuttavia, l’analisi dei dati di questo ultimo anno ha evidenziato alcune problematiche in grado di influenzare negativamente lo sviluppo delle piante. Temperature al di sotto dei valori critici, infatti, ci obbligano all’uso di frangivento, per ridurre il rischio di esposizione a venti freddi, e al ricorso ad apprestamenti protettivi delle singole piante nei primi anni dell’impianto. Dalle analisi pomologiche risulta un’ampia variabilità delle caratteristiche fisico-chimiche in grado di offrire una ampia scelta commerciale. L’introduzione di queste nuove cultivar in Sicilia consentirebbe un ampliamento del calendario di maturazione da agosto fino a novembre, limitando il ricorso all’importazione, ma va ulteriormente approfondito in relazione ai fattori sopra esposti

    The allometric partition of whole body protein in lean fraction of growing pigs using information from three different datasets

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    The hypothesis that a single allometric relationship relating carcass lean protein (CLP) to whole body protein (WBP) can allow accurate estimates of CLP on pigs of different populations, sex and nutritional history, was tested. Three datasets of different origins were used. Data were representative of 548 pigs, castrated males and females, of 8 pig populations, serially slaughtered over ample empty body weight (EBW) ranges (from 22 to 217 kg). WBP and CLP ranged, respectively, from 2 to 28 and from 1 to 16 kg. The pooled data were run and the following relationship was found: CLP=0.497*WBP1.021 (CV=0.062; rsd=0.501 kg). The residuals were subjected to ANOVA to test the effects due to dataset, pig population within dataset and sex; significant differences between datasets mean residuals (+0.095, SE=0.041; -0.258, SE=0.094; -0.116, SE=0.055 kg, P<0.001) were observed. No differences due to sex and pig populations were found. The average residuals were low and only in few cases they differed from zero. Conclusions: CLP can be accurately predicted from WBP; the coefficients of this function are mainly influenced by the procedures of slaughtering, dissection, sampling and analysis

    A vision-based fully automated approach to robust image cropping detection

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    The definition of valid and robust methodologies for assessing the authenticity of digital information is nowadays critical to contrast social manipulation through the media. A key research topic in multimedia forensics is the development of methods for detecting tampered content in large image collections without any human intervention. This paper introduces AMARCORD (Automatic Manhattan-scene AsymmetRically CrOpped imageRy Detector), a fully automated detector for exposing evidences of asymmetrical image cropping on Manhattan-World scenes. The proposed solution estimates and exploits the camera principal point, i.e., a physical feature extracted directly from the image content that is quite insensitive to image processing operations, such as compression and resizing, typical of social media platforms. Robust computer vision techniques are employed throughout, so as to cope with large sources of noise in the data and improve detection performance. The method leverages a novel metric based on robust statistics, and is also capable to decide autonomously whether the image at hand is tractable or not. The results of an extensive experimental evaluation covering several cropping scenarios demonstrate the effectiveness and robustness of our approac
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