Selection by color and form in vision.

Whether attention to a local part of a visual display can prevent access to semantic information in form matching tasks with objects was studied. A first picture containing a line segment (the reference) was followed by 2 lateral objects also containing a line segment (a target and a distractor). Participants matched the line segments according to either their orientation or color. Effects of semantic information were assessed by manipulating the semantic relations among the pictures surrounding the reference, target, and distractor. Semantic information affected performance in the orientation matching task, but not in the color matching task. Results suggest the existence of separate selection mechanisms in vision. Selection of local colors for response purposes can be based on inhibition of the form pathway (eliminating semantic effects on matching). Selection within the form pathway can involve a bias toward global shape (the picture). Once attention is allocated to global shape, associated semantic representations are activated and semantic effects on matching emerge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Photo-oxidation in an O2 atmosphere: A powerful tool to elucidate the mechanism of UV-visible light oxidation of polymers - Application to the photodegradation of MDMO-PPV

This article describes a new approach to improve the analysis of the chemical modifications that result from the degradation of polymers under UV-visible light exposure in the presence of oxygen. The tool which is used consists of an irradiation chamber whose atmosphere is composed of ¹⁸O₂. The ¹⁸O₂ pressure inside the chamber and the hygrometry can be adjusted. In this study, particular attention was paid to the photo-oxidation of poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV). Using infrared spectroscopy, irradiation under the oxygen 18 atmosphere allowed discrimination between compounds formed via fixation of oxygen from the atmosphere and those formed by reorganisation of the matrix. In addition, irradiation of MDMO-PPV in an ¹⁸O₂ wet atmosphere allowed for detection of the presence of phenyl formate and aromatic ketone functions. This permitted validating the mechanism of photo-oxidation previously proposed. Additionally, with regard to blends made with MDMO-PPV and methano-fullerene[6,6]-phenyl C₆₁-butyric acid methyl ester ([60] PCBM), it was demonstrated that this technique facilitates the identification of the photo-oxidation products formed.     

Optical pulse sequence transmission through single-mode fibers:interference signal analysis

The transmission of a pulse sequence through a single-mode fiber is considered under first- and second-order dispersion. An expression is given for the output power signal envelope in terms of the Fourier transform of a spectral function. The output envelope is composed of two terms: a linear one which is a distorted replica of the information sequence, and a nonlinear interference term. The latter is expressed in a more meaningful way and analyzed. The results allow a characterization and a classification of the interference pulses in terms of physically intuitive parameters     

Phase reconstruction from reflectivity in fiber Bragg gratings

We propose a method for phase, time delay, and impulse response reconstruction from the spectral power reflectance or reflectivity in fiber Bragg gratings (FBGs). This method is based on causality and stability conditions and uses the Hilbert and Wiener-Lee transforms. In order to obtain a complete study of the algorithm, we have applied it to uniform and nonuniform fiber Bragg gratings. Finally, we get a complete characterization of a experimental uniform fiber Bragg grating, from the measured reflectivity, by means of the phase reconstruction algorithm. Results show a good agreement between exact and reconstructed functions     

Attention to orientation, size, luminance, and color: Attentional failure within the form domain.

Whether Ss can attend to physical dimensions of objects without access to semantic information about them was examined. Ss decided which of 2 laterally presented pictures, a target and a distractor, had the same orientation (Exp 1), size (Exp 2), luminance (Exp 3), or color (Exp 4) as a reference picture. In each experiment, the matching stimuli were either physically identical, semantically related, or semantically unrelated. The reference stimulus and the distractor were either semantically related or unrelated. When matching was based on orientation or on size, performance was facilitated when the matching stimuli were semantically related, and it was disrupted when the distractor was semantically related to the reference stimulus. Semantic effects were eliminated when matching was based on luminance or color. The results are discussed in terms of physiological data, form and surface information, and global and local processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

New Peptide-Conjugated Chlorin-Type Photosensitizer Targeting Neuropilin-1 for Anti-Vascular Targeted Photodynamic Therapy

Photodynamic therapy (PDT) is a cancer treatment modality that requires three components, namely light, dioxygen and a photosensitizing agent. After light excitation, the photosensitizer (PS) in its excited state transfers its energy to oxygen, which leads to photooxidation reactions. In order to improve the selectivity of the treatment, research has focused on the design of PS covalently attached to a tumor-targeting moiety. In this paper, we describe the synthesis and the physico-chemical and photophysical properties of six new peptide-conjugated photosensitizers designed for targeting the neuropilin-1 (NRP-1) receptor. We chose a TPC (5-(4-carboxyphenyl)-10,15, 20-triphenyl chlorine as photosensitizer, coupled via three different spacers (aminohexanoic acid, 1-amino-3,6-dioxaoctanoic acid, and 1-amino-9-aza-3,6,12,15-tetraoxa-10-on-heptadecanoic acid) to two different peptides (DKPPR and TKPRR). The affinity towards the NRP-1 receptor of the conjugated chlorins was evaluated along with in vitro and in vivo stability levels. The tissue concentration of the TPC-conjugates in animal model shows good distribution, especially for the DKPPR conjugates. The novel peptide–PS conjugates proposed in this study were proven to have potential to be further developed as future NRP-1 targeting photodynamic therapy agent.     

Digitally reconstructing Van Gogh's Field with Irises near Arles part 3: Determining the original colors

In earlier articles, we determined the spatial distributions and concentrations of all pigments used by Van Gogh in his painting Field with Irises near Arles. The colors of some pigments are expected to have changed over time, especially those of chrome yellow, cochineal, and eosin lake. For all pigments in this painting, we made physical paint reconstructions by following historical sources on raw materials and production processes, and we determined their optical properties. We combined this with pigment concentration maps to reconstruct the original colors of the painting digitally. When substituting the reconstruction paints into the calculations, we found that technical‐scientific data was not sufficient to resolve several issues. In those cases, discussions within the broad interdisciplinary team allowed us to make informed decisions. These issues refer to the representation of the sky area, and the original contributions of the red lake pigments to local colors. The digitally reconstructed colors of the painting show that due to discoloring of red lake pigments, the irises in the field have changed from a warm purple to purplish blue, and many pink spots in the field have turned to white. The range of yellows in the field has decreased and partly turned to dark brown. The digital reconstruction gives a better understanding of the color scheme used by Van Gogh when compared to remarks the artist made in letters when describing this painting. Also, the original color composition is seen to be aligned with color theories on which Van Gogh based his work.     

Tape Casting of Al2O3/ZrO2 Laminated Composites

Fracture toughness of ZrO₂-toughened alumina could he increased by macroscopic interfaces, such as those existing in laminated composites. In this work, tape casting was used to produce A/A or A/B laminates, where A and B can be Al₂O₃, Al₂O₃/5 vol% ZrO₂, and Al₂O₃/l0 vol% ZrO₂. An increase of toughness is observed, even in the Al₂O₃/Al₂O₃ laminates.     

Physisorption of hydrogen in single-walled carbon nanotubes

The interaction of hydrogen with single-walled carbon nanotubes (SWNTs) was analysed. A SWNT sample was exposed to D₂ or H₂ at a pressure of 2 MPa for 1 h at 298 or 873 K. The desorption spectra were measured by thermal desorption spectroscopy (TDS). A main reversible desorption site was observed throughout the range 77 to 320 K. The activation energy of this peak at about 90 K was calculated assuming first-order desorption. This corresponds to physisorption on the surface of the SWNTs (19.2±1.2 kJ/mol). A desorption peak was also found for multi-walled carbon nanotubes (MWNTs), and also for graphite samples. The hydrogen desorption spectrum showed other small shoulders, but only for the SWNT sample. They are assumed to originate from hydrogen physisorbed at sites on the internal surface of the tubes and on various other forms of carbon in the sample. The nanosized metallic particles (Co:Ni) used for nanotube growth did not play any role in the physisorption of molecular hydrogen on the SWNT sample. Therefore, it is concluded that the desorption of hydrogen from nanotubes is related to the specific surface area of the sample.