Search results for "PEG"

Terrain data compression using wavelet-tiled pyramids for online 3D terrain visualization

2013

Last years have witnessed the widespread use of online terrain visualization applications. However, the significant improvements achieved in sensing technologies have allowed an increasing size of the terrain databases. These increasing sizes represent a serious drawback when terrain data must be transmitted and rendered at interactive rates. In this paper, we propose a novel wavelet-tiled pyramid for compressing terrain data that replaces the traditional multiresolution pyramid usually used in wavelet compression schemes. The new wavelet-tiled pyramid modifies the wavelet analysis and synthesis processes, allowing an efficient transmission and reconstruction of terrain data in those applic…

Perceptually weighted optical flow for motion-based segmentation in MPEG-4 paradigm

2000

In the MPEG-4 paradigm, the sequence must be described in terms of meaningful objects. This meaningful, high-level representation should emerge from low-level primitives such as optical flow and prediction error which are the basic elements of previous-generation video coders. The accuracy of the high-level models strongly depends on the robustness of the primitives used. It is shown how perceptual weighting in optical flow computation gives rise to better motion estimates which consistently improve motion-based segmentation compared to equivalent unweighted motion estimates.

A Digital Watermarking Algorithm Based on Quantization of the DCT: Application on Medical Imaging

2013

International audience; The objective of this paper is to elaborate a new watermarking algorithm applied to the medical imaging. This algorithm must be invisible, robust and has a rate, relatively high, integrating data. The proposed method uses the standard JPEG compression for the integration of medical data. The insertion block is inserted just after the quantization phase. To control identification and eventually the correction (if possible) of the inserted data, we use a series of turbocodes to recover the inserted data, after application of several attacks. The simulation studies are applied on MRI medicals images.

Valutazione dell’assetto emoreologico in condizioni basali e dopo prova da sforzo cardio-polmonare in atleti che praticano attività sportiva con dive…

2011

Biologically-induced transition of bio-silica sol to mesoscopic gelatinous flocs: a biomimetic approach to a controlled fabrication of bio-silica str…

2012

Siliceous sponges form their skeletal elements, the spicules, enzymatically via the sponge-specific enzyme silicatein. The enzymatic product of silicatein in vitro is a bio-silica polymer that is not processed/hardened by phase separation. In the present study we applied a two-phase system to investigate the transition of bio-silica, formed by silicatein, from the lucid state to the opaque/turbid state. We report for the first time that the polyether polyethylene glycol [PEG] causes a rapid transition of the lucid bio-silica to the opaque/turbid state. For the experiments the recombinant silicatein from the demosponge Suberites domuncula had been used. This process is rapid (1 h) and procee…

Oscillatory dynamics of the Belousov-Zhabotinsky system in the presence of a self-assembling nonionic polymer. Role of the reactants concentration.

2010

In the present study, the role played by the reactants concentration on the nonlinear response of a Belousov–Zhabotinsky (BZ) system to the addition of a self-assembling non-ionic polymer, poly(ethylene glycol) (PEG), has been assessed. The oscillatory parameters are influenced to an extent that significantly depends on the concentration of both the polymer and the Belousov–Zhabotinsky components. The effects obtained were attributed to the reaction among some of the BZ key species and the backbone and the alcoholic functional groups of the polymer, both in its monomeric and aggregated forms. Support to the proposed perturbation mechanism has been provided by performing numerical simulation…

Improvement of solubility and biocompatibility of MnO based nanoparticles in aqueous solutions

2011

ABSTRACTMnO nanoparticles were surface modified using two different multifunctional polymers. By introducing a PEG group, the long term stability, MRI applicability and sterile filtration could be greatly improved. Furthermore, PEGylated MnO NPs were less toxic compared to non-PEGylated NPs. The results suggest that these nanoparticles are suitable for in vivo applications.

Polymer−Surfactant Interactions. A Quantitative Approach to the Enthalpy of Transfer of Poly(Ethylene Glycol)s from Water to the Aqueous Sodium Perfl…

2000

The enthalpy of transfer (ΔHt) of nonionic polymers at a fixed concentration from water to aqueous substrate solutions as a function of the substrate concentration (fSmS) was determined. The substrates studied are sodium perfluorobutanoate to sodium perfluorooctanoate, and the polymers are poly(ethyleneglycol)s with molecular weights of 400 and 35 000. For the PEG 400-sodium perfluoroheptanoate−water systems, measurements were also performed at some polymer compositions. As a general feature, the enthalpy of transfer steeply changes with fSmS, reaching a maximum beyond which it decreases, tending to level off. A qualitative analysis of the enthalpy data assigned the steep increase of ΔHt to…

From Biocompatible to Biodegradable: Poly(Ethylene Glycol)s with Predetermined Breaking Points

2013

Poly(ethylene glycol) (PEG) is the gold standard polymer for biomedical applications. PEG is known for its biocompatibility and antifouling properties and is widely used for bioconjugation. However, like other synthetic polymers in the field, PEG is not biodegradable, limiting its use for parenteral formulations and protein conjugation to a molecular weight range with a specific upper limit (commonly 40–60 kDa) to avoid polyether accumulation in human tissue. For these biomedical applications, but also for other purposes such as cleavable hydrogels and templates for porous membranes, several routes for the insertion of in-chain biocleavable moieties, such as acetals or disulfides, into PEG …

1983

Poly(ethylene glycol)s grated onto suitably functionalized, crosslinked polystyrenes were introduced as a new class of multidetachably immobilized hydrophilic macromolecular supports for the synthesis of peptides. This new polymeric carrier system facilitates both the homogeneous solvation of the reaction site and the insolubilization of the substrate, which are prerequisites for an efficient multistep synthesis using polymeric supports. In these support systems, a strongly solvated hydrophilic linear chain molecule, poly(ethylene glycol) (PEG)1 , is attached to an insoluble, crosslinked polystyrene through suitable anchoring linkages. At the free chain end of this supported PEG, amino acid…