5,951 research outputs found

    Neuroanatomy of the Killer Whale (Orcinus orca) From Magnetic Resonance Images

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    This article presents the first series of MRI-based anatomically labeled sectioned images of the brain of the killer whale (Orcinus orca). Magnetic resonance images of the brain of an adult killer whale were acquired in the coronal and axial planes. The gross morphology of the killer whale brain is comparable in some respects to that of other odontocete brains, including the unusual spatial arrangement of midbrain structures. There are also intriguing differences. Cerebral hemispheres appear extremely convoluted and, in contrast to smaller cetacean species, the killer whale brain possesses an exceptional degree of cortical elaboration in the insular cortex, temporal operculum, and the cortical limbic lobe. The functional and evolutionary implications of these features are discussed

    Calculation of the crystal-melt interfacial free energy of succinonitrile from molecular simulation

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    This is the publisher's version, also available electronically from http://scitation.aip.org/content/aip/journal/jcp/124/4/10.1063/1.2149859

    Supercooled-liquid and plastic-crystalline state in succinonitrile-glutaronitrile mixtures

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    We report a thorough characterization of the glassy phases of mixtures of succinonitrile and glutaronitrile via dielectric spectroscopy and differential scanning calorimetry. This system is revealed to be one of the rare examples where both glassy states of matter, a structurally disordered supercooled liquid and an orientationally disordered plastic crystal, can be prepared in the same material. Both disordered states can be easily supercooled, finally arriving at a structural-glass or a glassy-crystal state. Detailed investigations using broadband dielectric spectroscopy enable a comparison of the glassy dynamics in both phases. Just as previously demonstrated for supercooled-liquid and plastic-crystalline ethanol, our experiments reveal very similar relaxational behavior and glass temperatures of both disordered states. Thus the prominent role of orientational degrees of freedom in the glass transition, suggested on the basis of the findings for ethanol, is fully corroborated by the present work. Moreover, the fragilities of both phases are determined and compared for different mixtures. The findings can be well understood within an energy-landscape based explanation of fragility.Comment: 8 pages, 7 figure

    Realization of logically labeled effective pure states for bulk quantum computation

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    We report the first use of "logical labeling" to perform a quantum computation with a room-temperature bulk system. This method entails the selection of a subsystem which behaves as if it were at zero temperature - except for a decrease in signal strength - conditioned upon the state of the remaining system. No averaging over differently prepared molecules is required. In order to test this concept, we execute a quantum search algorithm in a subspace of two nuclear spins, labeled by a third spin, using solution nuclear magnetic resonance (NMR), and employing a novel choice of reference frame to uncouple nuclei.Comment: PRL 83, 3085 (1999). Small changes made to improve readability and remove ambiguitie

    Temperature development of glassy alpha-relaxation dynamics determined by broadband dielectric spectroscopy

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    We present the temperature dependence of alpha-relaxation times of 13 glass formers determined from broadband dielectric spectroscopy, also including data from aging measurements. The data sets partly cover relaxation-time ranges of up to 16 decades enabling a critical test of the validity of model predictions. For this purpose, the data are provided for electronic download. Here we employ these results to test the applicability of the Vogel-Fulcher-Tammann equation and a recently proposed new approach that was demonstrated to provide superior fits of a vast collection of viscosity data.Comment: 6 pages, 5 figures, final version with minor revisions according to referee demands. The relaxation time data published in the present work can be downloaded at http://link.aps.org/supplemental/10.1103/PhysRevE.81.05150

    Random Sequential Adsorption: From Continuum to Lattice and Pre-Patterned Substrates

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    The random sequential adsorption (RSA) model has served as a paradigm for diverse phenomena in physical chemistry, as well as in other areas such as biology, ecology, and sociology. In the present work, we survey aspects of the RSA model with emphasis on the approach to and properties of jammed states obtained for large times in continuum deposition versus that on lattice substrates, and on pre-patterned surfaces. The latter model has been of recent interest in the context of efforts to use pre-patterning as a tool to improve selfassembly in micro- and nanoscale surface structure engineering

    Relaxation dynamics and ionic conductivity in a fragile plastic crystal

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    We report a thorough characterization of the dielectric relaxation behavior and the ionic conductivity in the plastic-crystalline mixture of 60% succinonitrile and 40% glutaronitrile. The plastic phase can be easily supercooled and the relaxational behavior is investigated by broadband dielectric spectroscopy in the liquid, plastic crystalline, and glassy crystal phases. The very pronounced alpha-relaxation found in the spectra is characterized in detail. From the temperature dependence of the alpha-relaxation time, a fragility parameter of 62 was determined making this material one of the most fragile plastic-crystalline glass formers. A well-pronounced secondary and faint indications for a third relaxation process were found, the latter most likely being of Johari-Goldstein type. In addition, relatively strong conductivity contributions were detected in the spectra exhibiting the typical features of ionic charge transport.Comment: 8 pages, 7 figure
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