Superconducting Gap Structure of YNi2B2C Determined by Thermal Conductivity

In order to determine the superconducting gap structure of the borocarbide superconductor YNi₂B₂C, we have measured the angular variation of the c-axis thermal conductivity _zz in magnetic field rotated within the ab-planes. A clear fourfold symmetry with narrow cusps was observed in the angular variation of _zz . These results provide a strong evidence that the gap function has point nodes which are located along the a- and b-axes of the crystal.     

Gene expression within cell-sized lipid vesicles

Functional protein synthesis was observed in cell-sized lipid vesicles following encapsulation of a gene-expression system. Expression of rsGFP (red-shifted green fluorescent protein) within individual vesicles was observed by fluorescence microscopy. Interestingly, at the early stage of the reaction, the expression efficiency inside the vesicle was remarkably higher than that in the solution outside. The synthesized rsGFP in individual vesicles is safe from attack by proteinase K added to the external aqueous solution. Studies on cell-sized vesicles expressing protein should contribute to a fundamental understanding of certain aspects of living systems and will be useful for practical applications, such as the construction of microreactors.     

Structural phase transitions of methane+ethane mixed-gas hydrate induced by 1,1-dimethylcyclohexane

Methane+ethane+1,1-dimethylcyclohexane+water system was investigated by using Raman spectroscopy and isothermal phase equilibrium measurements under four-phase (gas+aqueous+large guest species+hydrate phases) equilibrium conditions at 288.15 K. The results suggest that three kinds of hydrate structures emerge at 288.15 K in the methane+ethane+1,1-dimethylcyclohexane+water system. The hydrate structure for this system changed from structure-H to structure-I via structure-II with increase in the mole ratio of ethane to methane.     

Effects of level of processing and rehearsal on frequency judgments.

Studied the effects of attention during encoding and rehearsal after initial encoding on frequency estimates in 3 experiments. Exp I found that varying the level of processing affected the linear increase in frequency estimates as a function of actual frequency, but varying processing after encoding with remember or forget cues had the greatest effects on the intercept of the function relating judged to actual frequency. Deeper levels of processing improved performance in a frequency discrimination task, whereas remember and forget cues had small effects on performance. In Exp II, materials that are easy to rehearse were compared with materials that are difficult to rehearse. Results were interpreted as evidence against a covert rehearsal explanation of slope effects in frequency estimation tasks because materials that are difficult to rehearse produced larger interactions between remember vs forget cues and frequency than materials that are easier to rehearse. In Exp III, an arithmetic task that was performed during word encoding affected the slope of the function relating judged to actual frequency, but the same task performed immediately after word presentation had no effect on frequency estimates. It is concluded that frequency is not stored automatically because attention during the initial stages of encoding affects it; however, attention devoted to processing after initial encoding does not affect the rate with which subjective frequency increases with repetitions. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Factors Influencing the Adhesion of Microorganisms to Surfaces

Starvation, growth phase, and carbon source influenced bacterial cell surface hydrophobicity. Both the number and kind of microorganisms that colonized metal surfaces depended on the type of metal and the presence of an imposed electrical potential. No significant differences in attachment and growth of a pure culture were observed when metal surfaces were dipped in an exogenous energy source. The chemical composition of naturally occurring adsorbed organic films on metal surfaces was shown to be independent of surface composition and polarization.     

Naming and locating the tops of rotated pictures.

Investigated whether and how pictures are mentally rotated to upright before they can be named. Four experiments were conducted with 12 college students in each, who were given the tasks of naming pictures of common objects with various orientations and locating their tops. In the naming task, Ss required more time the farther the picture was from upright, but the rotation effect was reduced after Ss had named each picture once, indicating that rotation may be required only for unfamiliar stimuli. The top locating task was faster with upright figures, but otherwise-oriented pictures required the same time regardless of orientation. Top-locating was faster than naming, indicating that "topness" may be guessed even in unfamiliar figures, while naming also involves searching one's semantic memory for a name. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Posture Control Model and Balance Test for the Prediction of Relative Postural Stability

A balance testing methodology has been developed based on a posture control model which defines relative stability by the degree to which a transient postural perturbation causes the center-of-pressure on the feet to approach the limits of the base-of-support. To minimize anticipatory adaptations and to ensure subject safety, the balance test uses a small-amplitude continuous random or pseudo-random perturbation. The data are used to identify an input-output model, which is then used to predict large-amplitude transient response. Sixtyfour normal subjects were tested, as well as five patients with vestibular lesions and five elderly subjects with a history of falling. Tests were performed with eyes open (EO) and blindfolded (BF), and the EO/BF ratio was calculated. The results showed highly significant differences between young (20-40) and elderly (61-79) normals, but no differences between males and females. In using the balance test to identify the balance-impaired individuals, the BF and EO/BF data provided higher success rates than the EO data. Depending on the modeling method used, the balance test was able to identify up to three of five vestibular patients and five of five elderly fallers, at a false positive rate of 25 percent in the normal subjects.     

Enhancement of low density lipoprotein binding to both low density lipoprotein receptor-positive and- negative cells by tetracycline antibiotics

Some tetracycline (TC) antibiotics, including TC and anhydrotetracycline, have been found to enhance specific binding of low density lipoprotein (LDL) to both LDL receptor-positive and-negative cells at relatively higher concentrations. When incubated at 37°C, the ability of LDL receptor-negative human fibroblasts to bind ¹²⁵I-LDL was increased from<2 to 45 ng/mg by 170 μM TC. In normal human fibroblasts and Hep G2 cells, ¹²⁵I-LDL binding was elevated 1.4- to 2-fold by 113 μM TC. The ¹²⁵I-LDL binding in the presence of TC was diminished by both heparin and EDTA. The enhancement by TC was not observed when ¹²⁵I-LDL binding was assayed at 4°C. TC enhanced LDL binding to paraformaldehyde-fixed Hep G2 cells, excluding LDL receptor induction in the mechanism. These results demonstrated that TC enhanced cellular LDL binding through a process not involving functional LDL receptors.     

Structural Analysis of the Complex between Penta-EF-Hand ALG-2 Protein and Sec31A Peptide Reveals a Novel Target Recognition Mechanism of ALG-2

ALG-2, a 22-kDa penta-EF-hand protein, is involved in cell death, signal transduction, membrane trafficking, etc., by interacting with various proteins in mammalian cells in a Ca²⁺-dependent manner. Most known ALG-2-interacting proteins contain proline-rich regions in which either PPYPXnYP (type 1 motif) or PXPGF (type 2 motif) is commonly found. Previous X-ray crystal structural analysis of the complex between ALG-2 and an ALIX peptide revealed that the peptide binds to the two hydrophobic pockets. In the present study, we resolved the crystal structure of the complex between ALG-2 and a peptide of Sec31A (outer shell component of coat complex II, COPII; containing the type 2 motif) and found that the peptide binds to the third hydrophobic pocket (Pocket 3). While amino acid substitution of Phe⁸⁵, a Pocket 3 residue, with Ala abrogated the interaction with Sec31A, it did not affect the interaction with ALIX. On the other hand, amino acid substitution of Tyr¹⁸⁰, a Pocket 1 residue, with Ala caused loss of binding to ALIX, but maintained binding to Sec31A. We conclude that ALG-2 recognizes two types of motifs at different hydrophobic surfaces. Furthermore, based on the results of serial mutational analysis of the ALG-2-binding sites in Sec31A, the type 2 motif was newly defined.