1,134 research outputs found

    Interstate educational programs: Are we ready?

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    During the past 15 years, Utah State University and other institutions have vigorously investigated the possibility of sharing educational resources across state lines. This concept, while very important to higher education\u27s future, has not been fully realized. The most obvious barriers have been lack of financial resources and working models. This paper outlines models and procedures that could benefit institutions in the development of cooperative degrees

    New high-pressure phase and equation of state of Ce2Zr2O8

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    In this paper we report a new high-pressure rhombohedral phase of Ce2Zr2O8 observed from high-pressure angle-dispersive x-ray diffraction and Raman spectroscopy studies up to nearly 12 GPa. The ambient-pressure cubic phase of Ce2Zr2O8 transforms to a rhombohedral structure beyond 5 GPa with a feeble distortion in the lattice. Pressure evolution of unit-cell volume showed a change in compressibility above 5 GPa. The unit-cell parameters of the high-pressure rhombohedral phase at 12.1 GPa are ah = 14.6791(3) {\AA}, ch = 17.9421(5) {\AA}, V = 3348.1(1) {\AA}3. The structure relation between the parent cubic (P2_13) and rhombohedral (P3_2) phases were obtained by group-subgroup relations. All the Raman modes of the cubic phase showed linear evolution with pressure with the hardest one at 197 cm-1. Some Raman modes of the high-pressure phase have a non-linear evolution with pressure and softening of one low-frequency mode with pressure is found. The compressibility, equation of state, and pressure coefficients of Raman modes of Ce2Zr2O8 are also reported.Comment: 33 pages, 8 figures, 6 table

    Properties of the ferrimagnetic double-perovskite A_{2}FeReO_{6} (A=Ba and Ca)

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    Ceramics of A_{2}FeReO_{6} double-perovskite have been prepared and studied for A=Ba and Ca. Ba_{2}FeReO_{6} has a cubic structure (Fm3m) with aa\approx 8.0854(1) \AA whereas Ca_{2}FeReO_{6} has a distorted monoclinic symmetry with a5.396(1)A˚,b5.522(1)A˚,c7.688(2)A˚a\approx 5.396(1) \AA, b\approx 5.522(1) \AA, c\approx 7.688(2) \AA and β=90.4(P21/n)\beta =90.4^{\circ} (P21/n). The barium compound is metallic from 5 K to 385 K, i.e. no metal-insulator transition has been seen up to 385 K, and the calcium compound is semiconducting from 5 K to 385 K. Magnetization measurements show a ferrimagnetic behavior for both materials, with T_{c}=315 K for Ba_{2}FeReO_{6} and above 385 K for Ca_{2}FeReO_{6}. A specific heat measurement on the barium compound gave an electron density of states at the Fermi level, N(E_{F}) equal to 6.1×1024eV1mole1\times 10^{24} eV^{-1}mole^{-1}. At 5 K, we observed a negative magnetoresistance of 10 % in a magnetic field of 5 T, but only for Ba_{2}FeReO_{6}. Electrical, thermal and magnetic properties are discussed and compared to the analogous compounds Sr_{2}Fe(Mo,Re)O_{6}.Comment: 5 pages REVTeX, 7 figures included, submitted to PR

    Increased susceptibility to repeated freeze-thaw cycles in Escherichia coli following long-term evolution in a benign environment

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    BACKGROUND: In order to study the dynamics of evolutionary change, 12 populations of E. coli B were serially propagated for 20,000 generations in minimal glucose medium at constant 37°C. Correlated changes in various other traits have been previously associated with the improvement in competitive fitness in the selective environment. This study examines whether these evolved lines changed in their ability to tolerate the stresses of prolonged freezing and repeated freeze-thaw cycles during adaptation to a benign environment. RESULTS: All 12 lines that evolved in the benign environment for 20,000 generations are more sensitive to freeze-thaw cycles than their ancestor. The evolved lines have an average mortality rate of 54% per daily cycle, compared to the ancestral rate of 34%. By contrast, there was no significant difference between the evolved lines and their ancestor in mortality during prolonged freezing. There was also some variability among the evolved lines in susceptibility to repeated freeze-thaw cycles. Those lines that had evolved higher competitive fitness in the minimal glucose medium at 37°C also had higher mortality during freeze-thaw cycles. This variability was not associated, however, with differences among lines in DNA repair functionality and mutability. CONCLUSION: The consistency of the evolutionary declines in freeze-thaw tolerance, the correlation between fitness in glucose medium at 37°C and mortality during freeze-thaw cycles, and the absence of greater declines in freeze-thaw survival among the hypermutable lines all indicate a trade-off between performance in minimal glucose medium at 37°C and the capacity to tolerate this stress. Analyses of the mutations that enhance fitness at 37°C may shed light on the physiological basis of this trade-off

    Evolutionary conservation and divergence of the transcriptional regulation of bivalve shell secretion across life history stages

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    Acknowledgements and Funding Information We are grateful to Andrew Gillis for use for paraffin histology and microscopy equipment and enthusiastic support of this work and the Rothera marine team for collecting the adult Laternula elliptica broodstock. This work was supported by UKRI Natural Environment Research Council (NERC) Core Funding to the British Antarctic Survey, a DTG Studentship (Project Reference: NE/J500173/1) and a Junior Research Fellowship to V.A.S. from Wolfson College, University of Cambridge. Review History: https://www.webofscience.com/api/gateway/wos/peer-review/10.1098/rsos.221022/Peer reviewedPublisher PD

    Computationally predicted gene regulatory networks in molluscan biomineralization identify extracellular matrix production and ion transportation pathways

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    Acknowledgements We would like to thank Prof Peter Kille for constructive comments on this work. Funding This work was supported by the Natural Environment Research Council Core Funding to the British Antarctic Survey, a DTG Studentship (Project Reference: NE/J500173/1) to V.A.S. and a Junior Research Fellowship to V.A.S from Wolfson College, University of Cambridge. Conflict of Interest: none declared.Peer reviewedPublisher PD

    Characterisation of the mantle transcriptome and biomineralisation genes in the blunt-gaper clam, Mya truncata

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    Members of the Myidae family are ecologically and economically important, but there is currently very little molecular data on these species. The present study sequenced and assembled the mantle transcriptome of Mya truncata from the North West coast of Scotland and identified candidate biomineralisation genes. RNA-Seq reads were assembled to create 20,106 contigs in a de novo transciptome, 18.81% of which were assigned putative functions using BLAST sequence similarity searching (cuttoff E-value 1E − 10). The most highly expressed genes were compared to the Antarctic clam (Laternula elliptica) and showed that many of the dominant biological functions (muscle contraction, energy production, biomineralisation) in the mantle were conserved. There were however, differences in the constitutive expression of heat shock proteins, which were possibly due to the M. truncata sampling location being at a relatively low latitude, and hence relatively warm, in terms of the global distribution of the species. Phylogenetic analyses of the Tyrosinase proteins from M. truncata showed a gene expansion which was absent in L. elliptica. The tissue distribution expression patterns of putative biomineralisation genes were investigated using quantitative PCR, all genes showed a mantle specific expression pattern supporting their hypothesised role in shell secretion. The present study provides some preliminary insights into how clams from different environments – temperate versus polar – build their shells. In addition, the transcriptome data provides a valuable resource for future comparative studies investigating biomineralisation
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