New analytic solutions of the non-relativistic hydrodynamical equations

New solutions are found for the non-relativistic hydrodynamical equations. These solutions describe expanding matter with a Gaussian density profile. In the simplest case, thermal equilibrium is maintained without any interaction, the energy is conserved, and the process is isentropic. More general solutions are also obtained that describe explosions driven by heat production, or contraction of the matter caused by energy loss.Comment: 6 pages, LaTeX. Submitted to Physics Letters B. Shortened from 9 pages, errors corrected in the "More general solutions" sectio

Compressibility of rotating black holes

Interpreting the cosmological constant as a pressure, whose thermodynamically conjugate variable is a volume, modifies the first law of black hole thermodynamics. Properties of the resulting thermodynamic volume are investigated: the compressibility and the speed of sound of the black hole are derived in the case of non-positive cosmological constant. The adiabatic compressibility vanishes for a non-rotating black hole and is maximal in the extremal case --- comparable with, but still less than, that of a cold neutron star. A speed of sound $v_s$ is associated with the adiabatic compressibility, which is is equal to $c$ for a non-rotating black hole and decreases as the angular momentum is increased. An extremal black hole has $v_s^2=0.9 \,c^2$ when the cosmological constant vanishes, and more generally $v_s$ is bounded below by $c/ {\sqrt 2}$.Comment: 8 pages, 1 figure, uses revtex4, references added in v

Calculation of X-Ray Signals from Karolyhazy Hazy Space-Time

Karolyhazy's hazy space-time model, invented for breaking down macroscopic interferences, employs wave-like gravity disturbances. If so, then electric charges would radiate permanently. Here we discuss the observational consequences of the radiation. We find that such radiation is excluded by common experimental situations.Comment: 7 pages, PlainTe

Critique of proposed limit to space--time measurement, based on Wigner's clocks and mirrors

Based on a relation between inertial time intervals and the Riemannian curvature, we show that space--time uncertainty derived by Ng and van Dam implies absurd uncertainties of the Riemannian curvature.Comment: 5 pages, LaTex, field "Author:" correcte

“The dog chase the cat”: Grammaticality judgments by Hungarian-speaking children with language impairment

In a previous study of language production, a group of Hungarian-speaking children with language impairment (LI) committed a larger number of errors than typically developing peers on verb inflections that mark person, number, tense, and definiteness (Lukács et al. 2009b). However, the error forms produced often differed from the correct form by only a single dimension (e.g., person, number, tense, or definiteness) with no single dimension proving consistently problematic. In the present study, we sought to determine whether a similar pattern applied to the children’s understanding of verb inflections, as reflected in a grammaticality judgment task. We compared the performance of 17 Hungarian-speaking children with language impairment (LI) between ages 8;0 and 11;9 with typically developing children between 6;10 and 11;1 years individually matched on receptive vocabulary raw scores (VC) and also to a control group of children matched on chronological age (AC; between 8;1–12;1). We obtained grammaticality judgments for 68 sentences, including 56 ill-formed sentences that contained a single error of person, number, tense, definiteness, or morphophonology. As the AC group performed at ceiling, the analysis focused on comparisons between the LI and VC groups. Besides comparing accuracy scores in the two groups, we tested how well performance could be predicted by a test of grammatical comprehension (TROG) and a measure of nonword repetition ability obtained prior to the administration of the grammaticality judgment task. There were no significant group differences in the accuracy of grammaticality judgments. Both groups recognized well-formed sentences, and agreement errors of number, person or definiteness, significantly more accurately than tense or morphophonological errors. Although there was no difference between performance levels of the LI and the VC groups, we found differences between the two groups in the types of measures that were most closely tied to performance on the grammaticality judgment task. Performance in the LI group was strongly associated with nonword repetition span, while in the VC group, TROG performance was associated with grammaticality judgment performance. These results suggest that the same level and pattern of performance can be supported by different background mechanisms in typical and atypical language development

Kant's philosophy of the aesthetic and the philosophy of praxis

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2012 Association for Economic and Social Analysis.This essay seeks to reconstruct the terms for a more productive engagement with Kant than is typical within contemporary academic cultural Marxism, which sees him as the cornerstone of a bourgeois model of the aesthetic. The essay argues that, in the Critique of Judgment, the aesthetic stands in as a substitute for the missing realm of human praxis. This argument is developed in relation to Kant's concept of reflective judgment that is in turn related to a methodological shift toward inductive and analogical procedures that help Kant overcome the dualisms of the first two Critiques. This reassessment of Kant's aesthetic is further clarified by comparing it with and offering a critique of Terry Eagleton's assessment of the Kantian aesthetic as synonymous with ideology