Maskless Preparation of Spatially-Resolved Plasmonic Nanoparticles on Polydimethylsiloxane via In Situ Fluoride-Assisted Synthesis

Here, a fluoride-assisted route for the controlled in-situ synthesis of metal nanoparticles (NPs) (i.e., AgNPs, AuNPs) on polydimethylsiloxane (PDMS) is reported. The size and coverage of the NPs on the PDMS surface are modulated with time and over space during the synthetic process, leveraging the improved yield (10×) and faster kinetics (100×) of NP formation in the presence of F⁻ ions, compared to fluoride-free approaches. This enables the maskless preparation of both linear and step gradients and patterns of NPs in 1D and 2D on the PDMS surface. As an application in flexible plasmonics/photonics, continuous and step-wise spatial modulations of the plasmonic features of PDMS slabs with 1D and 2D AgNP gradients on the surface are demonstrated. An excellent spatially resolved tuning of key optical parameters, namely, optical density from zero to 5 and extinction ratio up to 100 dB, is achieved with AgNP gradients prepared in AgF solution for 12 minutes; the performance are comparable to those of commercial dielectric/interference filters. When used as a rejection filter in optical fluorescence microscopy, the AgNP-PDMS slabs are able to reject the excitation laser at 405 nm and retain the green fluorescence of microbeads (100 µm) used as test cases.     

Logarithmic wavelength demultiplexers

A general approach for a full 1 /spl times/ N demultiplexer using a tree of filter stages is proposed. The device architecture is compact, requiring at least N - 1 filter stages, and flexible, as each filter stage can be arbitrarily designed, with the only constraint of the half-band power property. The filters can be realized using any optical filtering techniques as thin-film interference, Bragg gratings, or planar delay-line circuits. The performances of the proposed architecture are illustrated with respect to different lattice-form finite impulse response (FIR) and infinite impulse response (IIR) filter stages, showing that the demultiplexer inherently presents low crosstalk and flat passband. A design example of a 1 /spl times/ 4 demultiplexer consisting of three all-pass (AP) filters is compared with a generalized Mach-Zehnder interferometer (MZI) with four AP filters in its arms, showing that the two approaches achieve similar results.     

QoS assessment of 3G video-phone calls by tracing watermarking exploiting the new colour space `YST?

Tracing watermarking has been recently proposed as a technique to provide a blind measure of the quality of service of the communication link, focusing on multimedia communication scenarios. 3G communication scenarios, where each customer transmits both voice and MPEG-4 video sequences in real time, have been considered. Typical video-phone call consists of close shots of speakers, framing their face in the foreground. For such particular application, a novel colour space (YST) is adopted to minimise the perceptual distortions on face coding introduced by watermarking. In the YST space, the luminance component (Y) is the same as in conventional YUV space, whereas the vectors S and T lie within the chrominance (UV) plane. The S (skin) component is a linear combination of U and V obtained as the 'average' chrominance estimated from an assorted set human faces to achieve a reasonable generalisation. The third component, T, is defined as orthogonal to the YS plane. The results show the benefits obtained in digital watermarking by the new representation against the conventional approach. In fact, the sensitivity of the YST representation outperforms the conventional one in terms of objective (mean square error, peak signal-to-noise ratio) and subjective (video-quality metrics) indicators.     

Hidden Markov modeling using a dominant state sequence with application to speech recognition

Approximate maximum likelihood (ML) hidden Markov modeling using the most likely state sequence (MLSS) is examined and compared with the exact ML approach that considers all possible state sequences. It is shown that for any hidden Markov model (HMM), the difference between the approximate and the exact normalized likelihood functions cannot exceed the logarithm of the number of states divided by the dimension of the output vectors (frame length), which is negligible for typically used values of vector dimension (128–256) and number of states (2–30). Furthermore, for Gaussian HMMs and a given observation sequence, the MLSS is typically the sequence of nearest neighbor states in the Itakura-Saito sense, and the posterior probability of any state sequence which departs from the MLSS in a single time instant decays exponentially with the frame length. Hence, for a sufficiently large frame length the exact and approximate ML approaches provide similar model estimates and likelihood values. The results and their implications on speech recognition are demonstrated in a set of experiments.     

What do we learn from binding features? Evidence for multilevel feature integration.

Four experiments were conducted to investigate the relationship between the binding of visual features (as measured by their aftereffects on subsequent binding) and the learning of feature-conjunction probabilities. Both binding and learning effects were obtained, but they did not interact. Interestingly, (shape-color) binding effects disappeared with increasing practice, presumably because of the fact that only 1 of the features involved was relevant to the task. However, this instability was only observed for arbitrary, not highly overlearned combinations of simple geometric features and not for real objects (colored pictures of a banana and strawberry), where binding effects were strong and resistant to practice. These findings suggest that learning has no direct impact on the strength or resistance of bindings or on speed with which features are bound; however, learning does affect the amount of attention particular feature dimensions attract, which again can influence which features are considered in binding. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Fast Inverse Motion Compensation Algorithms for MPEG and for Partial DCT Information

In prior work, we developed a fast inverse motion compensation method that can be implemented directly on the DCT domain representation derived from the compressed bitstreams conforming to MPEG, H.261, and H.263 standards. That work was restricted to compressed-domain representations wherein the motion-vectors have integer pel accuracy. Here, we extend this work to fractional-pel accurate motion-vectors. We also extend the prior work to speed up the inverse motion compensation process in the DCT domain by explicitly exploiting the sparseness of the DCT domain representation. Using partial DCT information, we show that the DCT domain method has substantially lower operation count than the conventional spatial domain approach which requires decompression followed by inverse motion-compensation.     

Immunocytochemical evaluation of protein kinase C translocation to the inner nuclear matrix in 3T3 mouse fibroblasts after IGF-I treatment

The complex pathway which links the agonist-cell membrane receptor binding to the response at the genome level involves, among other elements, protein kinase C (PKC). Agonists acting at the cell membrane can affect an autonomous nuclear polyphosphoinositide signaling system inducing an activation of nuclear phosphoinositidase activity and a subsequent translocation of PKC to the nuclear region. The fine localization of PKC has been investigated by means of electron microscopy quantitative immunogold labeling in 3T3 mouse fibroblasts, mitogenically stimulated by IGF-I. The enzyme, which in untreated cells is present in the cytoplasm, except for the organelles, and in the nucleoplasm, after IGF-I treatment is reduced in the cytoplasm and almost doubled in the nucleus. The PKC isoform translocated to the nucleus is the alpha isozyme, which is found not only associated with the nuclear envelope but mainly with the interchromatin domains. By using in situ matrix preparations, PKC appears to be retained at the nuclear matrix level, both at the nuclear lamina and at the inner nuclear matrix, suggesting a direct involvement in the phosphorylation of nuclear proteins which are responsible for the regulation of DNA replication.     

High dose intravenous immune globulins and plasma exchange in Guillain-Barré Syndrome

We report the effects of treatment with plasma-exchange (PE) and intravenous immune globulins (IVIg) in 36 out of 50 patients with Guillain-Barré syndrome (GBS) recruited by an incidence study in the Emilia-Romagna region of Italy. Comparison of the patients treated with PE and IVIg showed no significant differences in terms of effectiveness in improving the clinical course of GBS: at one month, respectively 11.1% and 25% had recovered, and 55.5% and 58.3% had improved by at least one grade. These results are in agreement with those of the Dutch GBS trial. No relapses were observed in either group. Moreover, our results showed no difference in clinical outcome at 1 and 3 months between the patients receiving only one therapy and those receiving two; a second cycle of therapy did not seem to improve the clinical course of the disease significantly. We conclude that PE and IVIg are both safe and effective therapies for GBS.     

Identifying a putative common binding site shared by substance P receptor and an anti-substance P monoclonal antibody

Substance P G-protein coupled receptor and the antigen recognitionsite of a monoclonal antibody raised against substance P sharea stretch of five contiguous identical amino acids. This observationprompted us to build an atomic model of both the receptor andthe antibody and to analyse their common features. In particular,we report here that a pocket of similar size and compositionis present in both proteins, strongly suggesting a similarityin the mode of binding of both macromolecules to substance P.From the analysis of our models, the available data on the modeof binding of the antibody to substance P and recent data onsubstance P receptor mutants, we concluded that the pocket isvery likely to be involved in binding of the C-terminal 'messagesequence' of the tachykinin. This allowed us to suggest specificsite-directed mutants of the receptor which should shed somelight on the mechanism of peptide recognition by G-protein coupledreceptors.