Fragile Existence

Because their disruption to government and business operations can be offset or mitigated through alternate means; that is, none of these scenarios threatens the existence of governments and businesses.

Fragile Existence

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A number of recent studies in the literature have reported the existence of unusual temperature dependence of the shear viscosity for a variety of glass-forming liquids that cannot be described with a single fragility index. Rather, these liquids display an apparent fragile-to-strong transition (FST) with lowering of temperature that was suggested to be indicative of a structural transition. In the present work we critique the accuracy of the high-temperature oscillation viscometry technique that was used almost exclusively for viscosity measurements of these liquids above their liquidus temperature. Viscosity measurements are carried out on binary Ge-Se chalcogenide liquids in their supercooled and stable states using conventional capillary and parallel-plate rheometry techniques and are compared with the oscillation viscometry data in the literature. Such comparisons conclusively demonstrate that the latter measurement technique often underestimates the viscosity by nearly an order of magnitude, especially at high temperatures. These results, when taken together, indicate that the observation of FST in glass-forming liquids is likely an artifact of the inaccuracy of the oscillation viscometry technique. Moreover, these results cast serious doubt on the reliability of the high-temperature oscillation viscometry data for metals and alloys that are prevalent in the literature.

We study the fragile-to-strong (F-S) transition of metallic glass-forming liquids (MGFLs) by measuring the thermal response during annealing and dynamic heating of La55Al25Ni5Cu15 glass ribbons fabricated at different cooling rates. We find that the glasses fabricated in the intermediate regime of cooling rates (15-25 m/s) exhibit an anomalous crystallization behavior upon reheating as compared to the glasses formed at other cooling rates. This anomalous crystallization behavior implies the existence of a thermodynamic F-S transition, could be used as an alternative method for detecting the F-S transition in MGFLs, and sheds light on the structure origin of the F-S transition. This work also contributes to obtaining a general thermodynamic picture of the F-S transition in supercooled liquids.

A preliminary scanning electron microscopical observation on the most common human chromosomal fragile site 3p14 of the peripheral lymphocytes was reported. It was shown that chromatid break or gap at 3p14 observed under SEM may be a sign of under-packing of DNA filaments and the possibility of various packing-patterns might be in existence. The result of the present work might be of significance in the understanding of natures of breaking or gap of chromatid and may be of help to the study of the mechanisms of chromosomal fragile site formation.

Simeon Herskovitz argued that the agency failed to consider the social, economic and cultural effects that would result from limiting grazing in a region where poverty is high and the fragile existence of the rural communities there depends on access to surrounding lands. 041b061a72