Does black-hole entropy make sense?

Bekenstein and Hawking saved the second law of thermodynamics near a black hole by assigning to the hole an entropyS _h proportional to the area of its event horizon. It is tempting to assume thatS _h possesses all the features commonly associated with the physical entropy. Kundt has shown, however, thatS _h violates several reasonable physical expectations. We review his criticism, augmenting it as follows: (a)S _h is a badly behaved state function requiring knowledge of the hole's future history; and (b) close analogs of event horizons in other space-times do not possess an “entropy.” We also discuss these questions: (c) IsS _h suitable for all regions of a black-hole space-time? And (b) shouldS _h be attributed to the exterior of a white hole? One can retainS _h for the interior (respectively, exterior) of a black (respectively, white) hole, but we reject this as contrary to the information-theoretic derivation of horizon entropy given by Bekenstein. The total entropy defined by Kundt (all ordinary entropy on space-section cutting through the hole, no horizon term) and that of Bekenstein-Hawking (ordinary entropy outside horizon plus horizon term) appear to be complementary concepts with separate domains of validity. In the most natural choice, an observer inside a black hole will use Kundt's entropy, and one remaining outside that of Bekenstein-Hawking.     

A field study to assess the effects of wearing hearing protectors on the perception of warning sounds in an industrial environment

A field study has been performed which assessed the effectiveness of two warning sounds under realistic factory conditions. The thirty subjects were press operators who were involved in their regular work activities during the course of the experiment. The noise levels at their work stations were in the range 85 to 95 dB(A). The warning sound, plus four other irrelevant sounds, each at one of five different intensities, were presented via a loudspeaker in random order and at random time intervals (mean inter-stimulus interval, 30 s; range, 10 to 50 s). The influence of the factors hearing level and age of the subjects and use of hearing protection were investigated.The results showed significant differences between the intentional and incidental warning sounds investigated. Whilst the perception of the intentional horn warning sound was unaffected by the hearing sensitivity of the subjects and the wearing of hearing protectors, these two factors had a significant effect on the perception, as a warning, of the clinking sound of metal components. Subjects classified as having a substantial hearing loss perceived, on average, 18 percent fewer clinking sounds than those subjects with normal hearing or a mild hearing loss and, when wearing hearing protectors, the subjects overall perceived, on average, 9 percent fewer clinks. It is of note that the results of the field study differ from those of earlier laboratory-based experiments in finding that the distinctive intentional warning sound was not entirely reliable as a warning, even at levels substantially above its masked threshold, and in observing more than double the adverse effect of wearing hearing protection.     

Bonding studies of compounds of boron and the group IV elements : X. Photoelectron spectra of compounds Me4M (MC,Si, Ge,Sn, or Pb) and the lack of participation of M d-orbitals

The question of d-orbital participation by the central metal M in molecules containing second and higher row elements is critically examined in relation to the photoelectron spectra of the Group IV compounds Me₄M. It is shown that the splitting between the two strictly symmetry-determined CH levels 1t₁ and 1e drops monotonically from 1.3₅ eV in neopentane to approximately zeor in tetramethyl-plumbane, as is consistent with the decreasing through-space interactions in the (CH₃)₄ tetrahedron. Within the limits of the spectroscopic resolution, d-orbital participation is therefore discounted, as this would tend to increase the separation between these two levels on going down the series.     

A study of the action of wild fires on remote forests

A stochastic model is developed to describe interaction of fires and vegetation in remote forest regions to demonstrate that, given certain circumstances, fires have a dominant effect on the long term, as well as the short term, forest structure. The model describes interactions peculiar to rainforest regions of Tasmania, Australia, but can be adapted to any situation where a similar dependence of vegetation on fires exists.     

Edge plane sites on highly ordered pyrolytic graphite as templates for making palladium nanowires via electrochemical decoration

An approach for the fabrication of metal nanowires is presented. Palladium wires with diameters less than 50 nm were produced by electrochemical decoration of step edge sites on the surface of highly ordered pyrolytic graphite via the following three steps. First an electrochemical activation step was used to oxidize the edge plane sites on highly ordered pyrolytic graphite surfaces in 0.5 M Na(2)SO(4). Second, a potential cycling step in a 1 mM PdCl(2) solution in 0.1 M H(2)SO(4) was used to form palladium oxide (s) and/or complexes of Pd on the step edges. Third, Pd nanowires were formed by electroreduction after transfer of the graphite to 0.1 M H(2)SO(4). The resulting wires showed a high degree of uniformity. A merit of this approach is that it allowed metal nanowires to be fabricated without the simultaneous formation of nanoparticles on the basal plane terraces, in contrast to other studies of this type. The mesoscopic palladium wires are shown to be useful for the electrochemical sensing of hydrazine.