Polarization entangled state measurement on a chip

The emerging strategy to overcome the limitations of bulk quantum optics consists of taking advantage of the robustness and compactness achievable by the integrated waveguide technology. Here we report the realization of a directional coupler, fabricated by femtosecond laser waveguide writing, acting as an integrated beam splitter able to support polarization encoded qubits. This maskless and single step technique allows to realize circular transverse waveguide profiles able to support the propagation of Gaussian modes with any polarization state. Using this device, we demonstrate the quantum interference with polarization entangled states and singlet state projection.Comment: Revtex, 5+2 pages (with supplementary information), 4+1 figure

Design of Farthest-Point Masks for Image Halftoning

In an earlier paper, we briefly presented a new halftoning algorithm called farthest-point halftoning. In the present paper, this method is analyzed in detail, and a novel dispersion measure is defined to improve the simplicity and flexibility of the result. This new stochastic screen algorithm is loosely based on Kang's dispersed-dot ordered dither halftone array construction technique used as part of his microcluster halftoning method. Our new halftoning algorithm uses pixelwise measures of dispersion based on one proposed by Kang which is here modified to be more effective. In addition, our method exploits the concept of farthest-point sampling (FPS), introduced as a progressive irregular sampling method by Eldar et al. but uses a more efficient implementation of FPS in the construction of the dot profiles. The technique we propose is compared to other state-of-the-art dither-based halftoning methods in both qualitative and quantitative manners

The regions of the sequence most exposed to the solvent within the amyloidogenic state of a protein initiate the aggregation process.

Formation of misfolded aggregates is an essential part of what proteins can do. The process of protein aggregation is central to many human diseases and any aggregating event needs to be prevented within a cell and in protein design. In order to aggregate, a protein needs to unfold its native state, at least partially. The conformational state that is prone to aggregate is difficult to study, due to its aggregating potential and heterogeneous nature. Here, we use a systematic approach of limited proteolysis, in combination with electrospray ionisation mass spectrometry, to investigate the regions that are most flexible and solvent-exposed within the native, ligand-bound and amyloidogenic states of muscle acylphosphatase (AcP), a protein previously shown to form amyloid fibrils in the presence of trifluoroethanol. Seven proteases with different degrees of specificity have been used for this purpose. Following exposure to the aggregating conditions, a number of sites along the sequence of AcP become susceptible to proteolytic digestion. The pattern of proteolytic cleavages obtained under these conditions is considerably different from that of the native and ligand-bound conformations and includes a portion within the N-terminal tail of the protein (residues 6-7), the region of the sequence 18-23 and the position 94 near the C terminus. There is a significant overlap between the regions of the sequence found to be solvent-exposed from the present study and those previously identified to be critical in the rate-determining steps of aggregation from protein engineering approaches. This indicates that a considerable degree of solvent exposure is a feature of the portions of a protein that initiate the process of aggregation

Nonlinear kernel based feature maps for blur-sensitive unsharp masking of JPEG images

In this paper, a method for estimating the blur regions of an image is first proposed, resorting to a mixture of linear and nonlinear convolutional kernels. The blur map obtained is then utilized to enhance images such that the enhancement strength is an inverse function of the amount of measured blur. The blur map can also be used for tasks such as attention-based object classification, low light image enhancement, and more. A CNN architecture is trained with nonlinear upsampling layers using a standard blur detection benchmark dataset, with the help of blur target maps. Further, it is proposed to use the same architecture to build maps of areas affected by the typical JPEG artifacts, ringing and blockiness. The blur map and the artifact map pair permit to build an activation map for the enhancement of a (possibly JPEG compressed) image. Extensive experiments on standard test images verify the quality of the maps obtained using the algorithm and their effectiveness in locally controlling the enhancement, for superior perceptual quality. Last but not least, the computation time for generating these maps is much lower than the one of other comparable algorithms

Context-Based Defading of Archive Photographs

We present an algorithm for the enhancement of contrast in digitized archive photographic prints. It aims at producing an adaptive enhancement based on the local context of each pixel and is able to operate without direct user's intervention. A relation between the variation of contrast at different resolutions and the local Lipschitz regularity of the image is exploited. In this way, each pixel is defaded according to its nature: noise, edge, or smooth region. This strategy provides for an algorithm that drastically reduces typical, annoying artifacts like halo effects and noise amplification

Optical sensing in microchip capillary electrophoresis by femtosecond laser written waveguides

Capillary electrophoresis separation in an on-chip integrated microfluidic channel is typically monitored with bulky, bench-top optical excitation/detection instrumentation. Optical waveguides allow confinement and transport of light in the chip directing it to a small volume of the microfluidic channel and collecting the emitted/transmitted radiation. However, the fabrication of optical waveguides or more complex photonic components integrated with the microfluidic channels is not a straightforward process, since it requires a localized increase of the refractive index of the substrate.\ud Recently, a novel technique has emerged for the direct writing of waveguides and photonic circuits in transparent glass substrates by focused femtosecond laser pulses.\ud In this work we demonstrate the integration of femtosecond laser written optical waveguides into a commercial microfluidic chip. We fabricate high quality waveguides intersecting the microchannels at arbitrary positions and use them to optically address with high spatial selectivity their content. In particular, we apply our technique to integrate optical detection in microchip capillary electrophoresis. Waveguides are inscribed at the end of the separation channel in order to optically excite the different plugs reaching that point; fluorescence from the labelled biomolecules crossing the waveguide output is efficiently collected at a 90° angle by a high numerical aperture optical fiber. The sensitivity of the integrated optical detection system was first evaluated filling the chip with a dye solution, obtaining a minimum detectable concentration of 40 pM. \ud After dynamic coating of the microchannels with an EPDMA polymer we demonstrate electrophoresis of an oligonucleotide plug with concentration down to 1 nM and wavelength-selective monitoring of on-chip separation of three fluorescent dyes. Work is in progress on separation and detection of fluorescent-labeled DNA fragments, targeting specific, diagnostically relevant regions of a template DNA, for application to the detection of chromosome aberrations

Methyl trans geranate and farnesoate as markers for Gewürztraminer grape skins and related distillates

Methyl ester of trans geranic and farnesoic acids, farnesol and two alpha-farnesene isomers are remarkable compounds in skins of mature grapes as well as in marc distillates of Traminer variety. Considerations about their level in both products of other floral varieties, like Yellow and Rose Muscats and Müller-Thurgau, as well as about their relationships with the main skin monoterpenols and other compounds, including two unidentified stereoisomeric sesquiterpenes present only in distillates, were discussed. Finally, results of PCA data treatments as for the distillates are show