609 research outputs found
Justifying the world as an aesthetic phenomenon
This article scrutinises one of the most challenging theses of Nietzsche's Birth of Tragedy, that only as an aesthetic phenomenon can existence and the world be (or appear to be) âjustifiedâ. Through a close examination of the work's frequently masked revaluation of a series of Greek sources of thinking, not least its âinversionâ of both the metaphysics and the aesthetics of Plato's Republic, the article shows how the thesis of aesthetic âjustificationâ is caught up in a tension between Apolline and Dionysian interpretations, the first entailing a quasi-Homeric sense that the Olympians justify human existence by living a transfigured form of it themselves, the second involving a tragic insight into reality as itself the creative work of a âworld-artistâ, the latter allusively associated by Nietzsche with the philosophy of Heraclitus.PostprintPeer reviewe
Normalization of Collisional Decoherence: Squaring the Delta Function, and an Independent Cross-Check
We show that when the Hornberger--Sipe calculation of collisional decoherence
is carried out with the squared delta function a delta of energy instead of a
delta of the absolute value of momentum, following a method introduced by
Di\'osi, the corrected formula for the decoherence rate is simply obtained. The
results of Hornberger and Sipe and of Di\'osi are shown to be in agreement. As
an independent cross-check, we calculate the mean squared coordinate diffusion
of a hard sphere implied by the corrected decoherence master equation, and show
that it agrees precisely with the same quantity as calculated by a classical
Brownian motion analysis.Comment: Tex: 14 pages 7/30/06: revisions to introduction, and references
added 9/29/06: further minor revisions and references adde
Influence Functionals and the Accelerating Detector
The influence functional is derived for a massive scalar field in the ground
state, coupled to a uniformly accelerating DeWitt monopole detector in
dimensional Minkowski space. This confirms the local nature of the Unruh
effect, and provides an exact solution to the problem of the accelerating
detector without invoking a non-standard quantization. A directional detector
is presented which is efficiently decohered by the scalar field vacuum, and
which illustrates an important difference between the quantum mechanics of
inertial and non-inertial frames. From the results of these calculations, some
comments are made regarding the possibility of establishing a quantum
equivalence principle, so that the Hawking effect might be derived from the
Unruh effect.Comment: 32 page
Pair Creation of Black Holes During Inflation
Black holes came into existence together with the universe through the
quantum process of pair creation in the inflationary era. We present the
instantons responsible for this process and calculate the pair creation rate
from the no boundary proposal for the wave function of the universe. We find
that this proposal leads to physically sensible results, which fit in with
other descriptions of pair creation, while the tunnelling proposal makes
unphysical predictions. We then describe how the pair created black holes
evolve during inflation. In the classical solution, they grow with the horizon
scale during the slow roll-down of the inflaton field; this is shown to
correspond to the flux of field energy across the horizon according to the
First Law of black hole mechanics. When quantum effects are taken into account,
however, it is found that most black holes evaporate before the end of
inflation. Finally, we consider the pair creation of magnetically charged black
holes, which cannot evaporate. In standard Einstein-Maxwell theory we find that
their number in the presently observable universe is exponentially small. We
speculate how this conclusion may change if dilatonic theories are applied.Comment: 29 pages, LaTeX, 3 figures, submitted to Phys. Rev. D; minor typos
corrected, missing minus sign in Eq. (3.11) inserte
Copper induces Cu-ATPase ATP7A mRNA in a fish cell line, SAF1
Copper transporting ATPase, ATP7A, is an ATP dependent copper pump present in all vertebrates, critical for the maintenance of intracellular and whole body copper homeostasis. Effects of copper treatment on ATP7A gene expression in fibroblast cells (SAF1) of the sea bream (Sparus aurata) were investigated by qRT-PCR and by a medium density microarray from a closely related species, striped sea bream (Lithognathus mormyrus). To discriminate between the effects of Cu and other metals, SAF1 cells were exposed to sub-toxic levels of Cu, Zn and Cd. Expression of Cu homeostasis genes copper transporter 1 (CTR1), Cu ATPase (ATP7A), Cu chaperone (ATOX1) and metallothionein (MT) together with the oxidative stress markers glutathione reductase (GR) and Cu/Zn superoxide dismutase (CuZn/SOD) were measured 0, 4 and 24 hours post-exposure by qRT-PCR. Microarray was conducted on samples from 4 hours post Cu exposure. Cu, Zn and Cd increased MT and GR mRNA levels, while only Cu increased ATP7A mRNA levels. Microarray results confirmed the effects of Cu on ATP7A and MT and in addition showed changes in the expression of genes involved in protein transport and secretion. Results suggest that ATP7A may be regulated at the transcriptional level directly by Cu and by a mechanism that is different from that exerteted by metals on MT genes
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Judging the difference between attractiveness and health: does exposure to model images influence the judgments made by men and women?
Recent research has shown facial adiposity (apparent weight in the face) to be a significant predictor of both attractiveness and health, thus making it an important determinant of mate selection. Studies looking at the relationship between attractiveness and health have shown that individuals differentiate between the two by preferring a lower weight for attractiveness than for health in female faces. However, these studies have either been correlational studies, or have investigated weight perceived from only the face. These differences have been discussed with regard to sociocultural factors such as pressure from parents, peers and also media, which has been seen to have the highest influence. While exposure to media images has been shown to influence womenâs own body image, no study has yet directly tested the influence of these factors on peopleâs preferred weight in other womenâs bodies. Here we examine how a short exposure to images of models influences menâs and womenâs judgments of the most healthy looking and attractive BMI in Malaysian Chinese womenâs bodies by comparing differences in preferences (for attractiveness and health) between groups exposed to images of models of varying attractiveness and body weight. Results indicated that participants preferred a lower weight for attractiveness than for health. Further, womenâs but not menâs preferred BMI for attractiveness, but not health, was influenced by the type of media images to which they were exposed, suggesting that short term exposure to model images affect womenâs perceptions of attractiveness but not health
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