Evidence for two types of spatial representations: Hemispheric specialization for categorical and coordinate relations.

Analyses of human object recognition abilities led to the hypothesis that 2 kinds of spatial relation representations are used in human vision. Evidence for the distinction between abstract categorical spatial relation representations and specific coordinate spatial relation representations was provided in 4 experiments. These results indicate that Ss make categorical judgments—on/off, left/right, and above/below—faster when stimuli are initially presented to the left cerebral hemisphere, whereas they make evaluations of distance—in relation to 2 mm, 3 mm, or 1 in. (2.54 cm)—faster when stimuli are initially presented to the right cerebral hemisphere. In addition, there was evidence that categorical representations developed with practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A set of electrophoretic molecular markers for strain typing and population genetic studies of Histoplasma capsulatum

A set of eleven biallelic and three multiallelic molecular markers have been developed to analyze populations of Histoplasma capsulatum. All markers are amplified by polymerase chain reaction (PCR) and can be readily scored using minimal amounts of template DNA. The 11 biallelic loci have polymorphic restriction endonuclease sites or small insertions or deletions which may be assessed by agarose gel electrophoresis. These markers are inherited in an unambiguous manner and are ideal for assessing structure and gene flow within US populations of H. capsulatum, but are monomorphic in non-US populations. Both length and sequence variation are present in the multiallelic loci, which can be scored by direct sequencing, polyacrylamide gel electrophoresis, or single-strand conformation polymorphism (SSCP): As they are hypervariable, the multiallelic loci can be used to type isolates and to assess the level of genetic variation within populations. Preliminary results indicate that the three multiallelic markers presented are sufficient to distinguish isolates at the individual level and are polymorphic in both US and non-US populations. This collection of molecular markers will be a useful tool in population and epidemiology studies of H. capsulatum.     

Correlation between left ventricular hypertrophy and GAA trinucleotide repeat length in Friedreich's ataxia

BACKGROUND: Friedreich's ataxia (FA), the most common inherited ataxia, is associated frequently with cardiac hypertrophy, and death is often cardiac related. Recently, the disease has been associated with a mutation that consists of an unstable expansion of GAA repeats in the first intron of the gene encoding frataxin on chromosome 9. METHODS AND RESULTS: We studied 44 consecutive patients with FA, determined the size of GAA expansions in the frataxin gene, and examined the relation between the genotype and cardiac phenotype assessed by M-mode and two-dimensional echocardiography. All the patients were homozygous for the mutation. The size of the GAA expansion on the smaller allele varied from 270 to 1200. We found a correlation between the size of GAA expansion and the left ventricular wall thickness (r = .51, P < .001) and the left ventricular mass index (r = .45, P = .002). Left ventricular hypertrophy was observed in 81% of patients with a number of GAA repeats above the median value of 770 compared with only 14% in the other group (P = .002). CONCLUSIONS: These data demonstrate that in FA, the severity of left ventricular hypertrophy is related to the number of GAA repeats. These results suggest that abnormalities of the gene encoding frataxin, a protein of unknown function highly expressed in the normal heart, may play an important role in the modulation of cardiac hypertrophy.     

USE OF NEPHELINE SYENITE IN FLOOR-TILE AND WALL-TILE BODIES*

The physical properties of wall-tile bodies and floor-tile bodies are described. The wall-tile bodies are fluxed respectively with nepheline syenite; feldspar; talc and feldspar; talc and syenite; talc, pyrophyllite, and syenite; and talc, pyrophyllite, and feldspar. Floor-tile bodies, developing at lower temperatures, may be formulated with nepheline syenite. The greater refractoriness of American clays used in these bodies, as compared to English clays, is compensated for by the increased fluxing action of nepheline syenite.     

Fourier transform infra-red study of uniaxially-oriented isotactic polystyrene

Fourier transform infra-red measurements have been made of the orientation in isotactic polystyrene as a function of draw ratio. Based on these results, new band assignments are made and orientation functions calculated.     

An infra-red study of model compounds of poly(tetramethylene terephthalate)

An infra-red spectroscopic investigation of the poly(tetramethylene terephthalate) model compounds butyl-dibenzoate: C₆H₅COO(CH₂)₄OCOC₆H₅ (i), 1,4-bis-butyl terephthalate: HO(CH₂)₄-OCO₆H₄COO(CH₂)₄-OH (ii), α-butyl-ω-butoxyterephthalaoyl-di-(tetramethylene terephthalate): H(CH₂)₄(OCOC₆H₄COO-(CH₂)₄-)₃-OH (iii), and α-butyl-ω-butoxyterephthalaoyl-tetra-(tetra-methylene terephthalate): HO(CH₂)₄-(OCOC₆H₄COO(CH₂)₄-)₅-OH (iv) is presented. The synthesis of (i) is also described. Spectroscopic evidence indicates that the crystal conformations of the aliphatic segments in (i) and (ii) closely resemble the extended all trans beta form of PTMT. Oligomers (iii) and (iv), however, are found to be more similar to the crumpled alpha crystal phase of PTMT.     

Nature of PMMA dissolution process by mixtures of acetonitrile/alcohol (poor solvent/nonsolvent) monitored by FTIR-imaging

The dissolution process of poly(methyl methacrylate), PMMA, in mixtures of the binary systems: acetonitrile/alcohol (methanol, ethanol and 1-propanol), individually poor and nonsolvents respectively for the polymer, was studied at 25 °C using FTIR imaging spectroscopy. To investigate this cosolvency phenomenon and the kinetics of the dissolution process, the spatial resolution and sensitivity of FTIR imaging were used. It has been found that the PMMA dissolution rate anomalously increases almost in a parabolic way independently of the solvent system used in this study. These results were interpreted assuming that the dissolution of a polymer by a mixture of solvents is governed by a complex dependence of the solvent molecules size and their thermodynamic characteristics. The kinetics of the PMMA dissolution by AcN/alcohol solvent mixtures were interpreted using conventional Arrhenius behavior in which the activation energy has a simple dependence on the thermodynamic quality and the molecular weight of the solvent mixture.     

Cellule pour etudes electrochimiques sous pression; application a l''etude de la force electromotrice de la pile Cu(Hg)/CuSO4/Hg2SO4/Hg

For a study of the possible electrochemical processes occurring in the formation of polymetallic marine nodules, a vessel has been adjusted for electrochemical studies which allows to attain a pressure of about 500 atm. In order to test this cell, we have been studying the influence of pressure on the electromotive force of the cell

and we have determined an experimental pressure coefficient (?E/?p)_T,ni = 1,04.10^?5 volt.atm^?1.     

Study of the Interfacial Reaction of Styrene/Maleic Anhydride Copolymerand (Amine)-Terminated Butadiene-Acrylonitrile Copolymer Using FTIR Imaging Techniques

The interfacial reaction between styrene/maleic anhydride copolymer (SMA) and amine-terminated butadiene-acrylonitrile copolymer (ATBA) was observed using Fourier transform infrared (FTIR) imaging spectroscopy. The anhydride and amine reacted to form an imide. Each component was detected using a characteristic wavenumber, which was 1601 cm -1 for SMA, 2237 cm -1 for ATBA, and 1701 cm -1 for the imide. FTIR images were taken as the reaction proceeded at 150, 160, 170, and 180°C. At low temperatures (150 and 160°C), diffusion-controlled kinetics were observed since interdiffusion between the reactants did not appear in the images. On the other hand, both the diffusion front and the reaction front are observed in the images at high reaction temperatures (170 and 180°C), which indicates that the kinetics became reaction-controlled rather than diffusion-controlled. Absorbance profiles were extracted from the images and used for the calculation of the extent of reaction. The data were analyzed using the Frederickson and Milner theory based on the assumption of diffusion-controlled kinetics, and this theory fit the low reaction temperature data.