Learning to Recognize Patterns: Changes in the Visual Field with Familiarity

Two studies were conducted to investigate changes which take place in the visual information processing of novel stimuli as they become familiar. Japanese writing characters (Hiragana and Kanji) which were unfamiliar to two native English speaking subjects were presented using a moving window technique to restrict their visual fields. Study time for visual recognition was recorded across repeated sessions, and with varying visual field restrictions. The critical visual field was defined as the size of the visual field beyond which further increases did not improve the speed of recognition performance. In the first study, when the Hiragana patterns were novel, subjects needed to see about half of the entire pattern simultaneously to maintain optimal performance. However, the critical visual field size decreased as familiarity with the patterns increased. These results were replicated in the second study with more complex Kanji characters. In addition, the critical field size decreased as pattern complexity decreased. We propose a three component model of pattern perception. In the first stage a representation of the stimulus must be constructed by the subject, and restricting of the visual field interferes dramatically with this component when stimuli are unfamiliar. With increased familiarity, subjects become able to reconstruct a previous representation from very small, unique segments of the pattern, analogous to the informativeness areas hypothesized by Loftus and Mackworth [J. Exp. Psychol., 4 (1978) 565].Inquiries or requests for reprints may be directed to any of the authors. Authors’ current addresses are: James M. Bebko, Department of Psychology, York University, 4700 Keele Street, North York, Ontario, Canada M3J 1P3; Keiji Uchikawa, Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226 Japan; Shinya Saida, Biosignaling Department, National Institute of Bioscience and Human-Technology, 1-1 Higashi, Tsukuba, Ibaraki 305 Japan; Mitsuo Ikeda, Department of Architecture, Kyoto University, Sakyo-ku, Kyoto 606 Japan.This research was conducted while the first author was supported by a Government of Japan Monbusho Research Fellowship at Tokyo Institute of Technology.     

Weight filtration of the limit mixed Hodge structure at infinity for tame polynomials

We give three new proofs of a theorem of C. Sabbah asserting that the weight filtration of the limit mixed Hodge structure at infinity of cohomologically tame polynomials coincides with the monodromy filtration up to a certain shift depending on the unipotent or non-unipotent monodromy part.     

Electrical probing of endothelial cell behaviour on a fibronectin/polystyrene/thiol/gold electrode by Faradaic electrochemical impedance spectroscopy (EIS)

The electrochemical impedance spectroscopy (EIS) technique has been shown to be an effective tool for monitoring endothelial cell behaviour on a multilayer functionalised gold electrode. Polystyrene, a reproducible model substrate, is deposited as a thin layer on a thiol functionalised gold electrode. Fibronectin, a protein promoting endothelial cell adhesion, is then adsorbed on the polystyrene surface. The different steps of this multilayer assembly are characterized by Faradaic impedance. The charge transfer resistance and the capacitance for the total layer are modified at each step according to the electrical properties of each layer. This gives the endothelial cells' electrical state in terms of its resistive and capacitive properties. In this study, the endothelial cell layer presents a specific charge transfer resistance equal to 1.55 kOmega cm(2) with no large defects in the cell layer, and a specific capacitance equal to few microF cm(-2) explained by the existence of pseudopods. These electrical properties are correlated to the endothelial cell viability, adhesion and cytoskeleton organization.     

Chemical compounds from Phoenician juniper berries (Juniperus phoenicea)

Natural chemical compounds are a widely researched topic worldwide because of their potential activity against cerebrovascular diseases. Chemicals from Juniperus phoenicea berries are reported in this study. Lipids (11%) from seeds are mainly unsaturated (86%). Minerals are also quantified like Na (63.8?mg per 100?g?DW) or K (373.9?mg per 100?g?DW). Total reduced sugars are ca 192.6?mg?g(-1)?DW. Polyphenols and flavonoids from berries are highly present with an average of 1764?±?174.3?mg gallic acid per 100?g?DW and 890?±?47.6?mg rutin per 100?g?DW, respectively. Mean free radical scavenging activities, determined by DPPH and ABTS, are 1337?±?126.2?mM TEAC per 100?g?DW and 1105.7?±?95.9?mM TEAC per 100?g?DW, respectively. All findings improve the possible presence of biologically active fractions in phytocomplex that could be used as such and/or extracted for the formulation of supplements and/or ingredients for the pharmaceutical industry.     

Bernstein–Sato polynomials of hyperplane arrangements

We show that the Bernstein–Sato polynomial (that is, the b-function) of a hyperplane arrangement with a reduced equation is calculable by combining a generalization of Malgrange’s formula with the theory of Aomoto complexes due to Esnault, Schechtman, Terao, Varchenko, and Viehweg in certain cases. We prove in general that the roots are greater than \(-2\) and the multiplicity of the root \(-1\) is equal to the (effective) dimension of the ambient space. We also give an estimate of the multiplicities of the roots in terms of the multiplicities of the arrangement at the dense edges, and provide a method to calculate the Bernstein–Sato polynomial at least in the case of 3 variables with degree at most 7 and generic multiplicities at most 3. Using our argument, we can terminate the proof of a conjecture of Denef and Loeser on the relation between the topological zeta function and the Bernstein–Sato polynomial of a reduced hyperplane arrangement in the 3 variable case.