Scaling properties in the production range of shear dominated flows

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

Characterization and development of different methods to extend shelf life of fresh cut fruit. Case study: novel controlled release system by layer-by-layer assembly

The research project aimed at the investigation of different methods for the storage of fresh-cut fruit. This case study relates to the proposal of an innovative controlled release system to improve the shelf life of ready-to-eat fruit. The methods applied during three research years included the application of active molecules from natural substances, some widely used in commerce and other tested for the first time; first analyzed in vitro and then applied in vivo. The under consideration methods concerned dipping, coating and the layer-by-layer assembly. The analysis carried out on the fruit have monitored pomological traits performances (soluble solids content, titratable acidity, pH, color, flesh firmness), the chemical profile (polyphenoloxidase, carotenoids) and microbial growth

On the Solved Turbulent Scales in Turbulent Plume Fires

Plume fires are characterized by a turbulent nature with a large number of different scales. LES is often used to solve the largest structures and to model the smallest ones. Grid size and time steps become decisive to place the limit between resolved and modelled turbulence. Significant information on this limit and its placement can be obtained with spectral analyses of the specific turbulent kinetic energy. While frequency analysis is relatively easy, an analysis in the wavenumber domain is more challenging. The IWC method, typically used in structures and acoustics, is used here for this purpose. IWC method allows to obtain wavenumber spectra with a better resolution than those obtained with a direct approach. Furthermore, in this paper the IWC method is also used in its reverse form to obtain frequency spectra. Although rather dense grids have been chosen, the number of nodes along the plume and their spacing is not such as to guarantee detailed wavenumber spectra with the direct approach and consequently with the reverse IWC. On the contrary, the IWC method provides wavenumber spectra in agreement with those obtained directly, but of much higher quality

Sull'identità delle Sante (XII secolo) nella navata maior del Duomo di Piacenza: una valutazione iconografica e contestuale

Il contributo prende in esame l'iconografia di cinque rilievi scolpiti posizionati come chiavi d'arco sopra le arcate longitudinali del duomo di Piacenza (parete sinistra). Attraverso l'apporto di alcuni tituli e di confronti iconografici viene riconosciuta per la prima volta la personificazione dell' Ecclesia, seguita da santa Giustina, la Theotokos, le martiri Candida e Paolina. Poste di fronte a Cristo, David e tre Profeti, sull'altra parete della navata grande, instaurano con questi un rapporto dialettico, definendo cos\uec un "quadro contestuale"

Image Forgery Localization via Fine-Grained Analysis of CFA Artifacts

In this paper, a forensic tool able to discriminate between original and forged regions in an image captured by a digital camera is presented. We make the assumption that the image is acquired using a Color Filter Array, and that tampering removes the artifacts due to the demosaicking algorithm. The proposed method is based on a new feature measuring the presence of demosaicking artifacts at a local level, and on a new statistical model allowing to derive the tampering probability of each 2 × 2 image block without requiring to know a priori the position of the forged region. Experimental results on different cameras equipped with different demosaicking algorithms demonstrate both the validity of the theoretical model and the effectiveness of our schem

Reverse engineering of double compressed images in the presence of contrast enhancement

Abstract-A comparison between two forensic techniques for the reverse engineering of a chain composed by a double JPEG compression interleaved by a linear contrast enhancement is presented here. The first approach is based on the well known peak-to-valley behavior of the histogram of double-quantized DCT coefficients, while the second approach is based on the distribution of the first digit of DCT coefficients. These methods have been extended to the study of the considered processing chain, for both the chain detection and the estimation of its parameters. More specifically, the proposed approaches provide an estimation of the quality factor of the previous JPEG compression and the amount of linear contrast enhancement

Nutritional Status, Breastfeeding, and Evolution of Infants with Acute Viral Bronchiolitis

Acute viral bronchiolitis is a common respiratory infectious disease of infancy. A prospective study was carried out with 175 infants aged up to six months to evaluate their nutritional and breastfeeding status as possible risk factors for unfavourable evolution of previously-healthy infants from a care hospital. Immunofluorescence test for virus and anthropometric assessment were performed. Outcomes were length of oxygen-use, length of hospital stay, and type of hospital unit needed. Seventy-three percent of the infants were well-nourished, 6% undernourished, 8.6% at a nutritional risk, 10.9% overweight, and 1.7% obese. Eighty-one percent of the undernourished and nutritionally at-risk infants and 72% of the well-nourished, overweight, and obese infants did not receive exclusive breastfeeding. The median length of hospital stay was four days and of oxygen-use was 60 hours. The nutritional status did not affect the clinical course of previously-healthy infants with acute viral brochiolitis. The duration of exclusive breastfeeding, but not type of breastfeeding, was inversely related to the length of oxygen-use and the length of hospital stay. Shorter exclusive breastfeeding was observed in infants who were assigned to a paediatric ward or to an intensive care unit. In conclusion, longer duration of breastfeeding was associated with better clinical outcomes

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

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