The game Gls(κ) is played on a complete Boolean algebra B, by two players. White and Black, in κ-many moves (where κ is an infinite cardinal). At the beginning White chooses a non-zero element p ∈ B. In the α-th move White chooses pα ∈ (0.p)p and Black responds choosing iα ∈ {0.1}. White wins the play iff $\bigwedge _{\beta \in \kappa}\bigvee _{\alpha \geq \beta }p_{\alpha}^{i\alpha}=0$ , where $p_{\alpha}^{0}=p_{\alpha}$ and $p_{\alpha}^{1}=p\ p_{\alpha}$ . The corresponding game theoretic properties of c.B.a.'s are (...) investigated. So. Black has a winning strategy (w.s) if κ ≥ π(B) or if B contains a κ -closed dense subset. On the other hand, if White has a w.s., then κ ∈ [h₂(B). π(B)). The existence of w.s. is characterized in a combinatorial way and in terms of forcing. In particular, if 2κ = κ ∈ Reg and forcing by B preserves the regularity of κ, then White has a w.s. iff the power 2κ is collapsed to κ in some extension. It is shown that, under the GCH, for each set S ⊆ Reg there is a c.B.a. B such that White (respectively. Black) has a w.s. for each infinite cardinal κ ∈ S (resp. κ ∉ S). Also it is shown consistent that for each κ ∈ Reg there is a c.B.a. on which the game Gls(κ) is undetermined. (shrink)

In this article, I explore how the twin forces of imperial and entomological power allowed Britain to shape locust research and control across Africa, the Middle East and South Asia from the 1920s to the early 1950s. Imperial power came from the size of the formal and informal empire, and alliances with other colonial powers to tackle a common threat to agriculture and trade. Entomological authority came primarily from the work of Boris Uvarov and his small team of museum and (...) fieldworkers based at the Imperial Bureau of Entomology (IBE), later the Imperial Institute of Entomology (IIE). I begin by discussing how Uvarov's phase theory of the origin of swarming changed the prospects for the control of locust plagues. The imperial gaze and networks of the IBE and IIE were suited to a problem that was transnational and transcontinental. In the 1930s, Britain was drawn into plans for international cooperation on locust organizations that met the needs of science, to give better sharing of knowledge, and the needs for science, to secure the resources for research and control. However, such organizations were only created during the Second World War, when new plagues threatened military operations, as I show in relation to the measures taken to control the red locust and desert locust. In the final section, I follow the fate of the wartime cooperation in initiatives to establish permanent control organizations. It is a story of the decline of British political power in locust affairs as the United Nations Food and Agriculture Organization and regional agencies took over. My account of British locust research and control reveals a neglected aspect of histories of entomology and imperial/colonial science, especially their international relations and the continuing importance of metropolitan research centres. (shrink)

We study the response of a uniformly accelerated model particle detector in a spacetime with compact spatial sections. The basic thermal character of the response re-emerges, in spite of the fact that the spacetime does not possess event horizons. Our model also permits a study of detector response to twisted field states.

The fine structure constant α ≡ e2/ c ≈ 1/137 is one of the fundamental parameters of the standard model of particle physics. There is a long history of attempts to derive the measured value of α from an underlying theory, or exhibit it in the form of a compact mathematical expression [2–4, 6, 8, 14–16]. The most significant advance in this endeavour was made by Dirac, who showed that if magnetic monopoles exist, with magnetic charge μ, then..

The massless Thirring model of a self-interacting ferinion field in a curved two-dimensional background spacetime is considered. The exact operator solution for the fields and the equation for the two-point function are given and used to examine the radiation emitted by a two-dimensional black hole. The radiation is found to be thermal in nature, confirming general predictions to this effect. We compute the particle spectrum of the Thirring fermions at finite temperature in Minkowski space and point out errors in a (...) previous attempt at this calculation. Finally we calculate the vacuum expectation value of the stress tensor in an arbitrary two-dimensional spacetime by exploiting the connection between the thermal Hawking radiation from a black hole and the value of the so-called conformal trace anomaly. The latter is also computed quite independently, using dimensional regularization, from general considerations of the renormalization group. (shrink)

of a logarithmic time dependence of the fine structure constant is apparently within the limits discussed if there is a corresponding logarithmic time dependence of the strong coupling constant also. Moreover the recent discover> of naturally occurring ' Pu places the Gamow hypothesis of e' r much nearer the allov'able limits than had previously been supposed.

The hypothesis that life’s rapid appearance on Earth justifies the belief that life is widespread in the universe has been investigated mathematically by Lineweaver and Davis (Astrobiol- ogy 2002;2:293–304). However, a rapid appearance could also be interpreted as evidence for a nonterrestrial origin. I attempt to quantify the relative probabilities for a non-indigenous ver- sus indigenous origin, on the assumption that biogenesis involves one or more highly im- probable steps, using a generalization of Carter’s well-known observer-selection argument. The analysis is (...) specifically applied to a Martian origin of life, with subsequent transfer to Earth within impact ejecta. My main result is that the relatively greater probability of a Mar- tian origin rises sharply as a function of the number of difficult steps involved in biogene- sis. The actual numerical factor depends on what is assumed about conditions on early Mars, but for a wide range of assumptions a Martian origin of life is decisively favored. By con- trast, an extrasolar origin seems unlikely using the same analysis. These results complement those of Lineweaver and Davis. Key Words: Origin of life—Mars—Probability theory— Carter—Transpermia. Astrobiology 3, 673–679. (shrink)

two dimensions, quantum radiation production is incompatible with a conserved and traceless T„,. We therefore resolve an ambiguity in our expression for Tr„, regularized by a geodesic point-separation procedure.

Inconsistencies in the usual interpretation of the absorber theory of radiation are exposed which invalidate an experiment proposed recently by Heron and Pegg. An earlier experiment by Partridge necessarily gave a null result owing to absorption on the far side of the Earth of any advanced radiation which may have been present.

Using a model quantum clock, I evaluate an expression for the time of a nonrelativistic quantum particle to transit a piecewise geodesic path in a background gravitational field with small spacetime curvature (gravity gradient), in the case that the apparatus is in free fall. This calculation complements and extends an earlier one (Davies 2004) in which the apparatus is fixed to the surface of the Earth. The result confirms that, for particle velocities not too low, the quantum and classical transit (...) times coincide, in conformity with the principle of equivalence. I also calculate the quantum corrections to the transit time when the de Broglie wavelengths are long enough to probe the spacetime curvature. The results are compared with the calculation of Chiao and Speliotopoulos (2003), who propose an experiment to measure the foregoing effects. (shrink)

Weak measurements offer new insights into the behavior of quantum systems. Combined with post-selection, quantum mechanics predicts a range of new experimentally testable phenomena. In this paper I consider weak measurements performed on time-dependent pre- and post-selected ensembles, with emphasis on the decay of excited states. The results show that the standard exponential decay law is a limiting case of a more general law that depends on both the time of post-selection and the choice of final state. The generalized law (...) is illustrated for two interesting choices of post-selection. (shrink)

An analogue of Hawking's black hole area theorem is proved for Friedmann-type cosmological models with event horizons. The generalised second law of thermodynamics is investigated in cases where the horizon shrinks.

The author proposes to delineate the basic outlines of an entirely new religio-metaphysical foundation for the religious, moral, and social convictions of modern Western man—an admittedly ambitious undertaking. More specifically, he wishes to nail the lid on the coffin of "the so-called Aristotelian substantialism," by means of an "interpretational synthesis" of the thought of Whitehead and that of Heidegger. Accordingly, he argues for an organismic view of history, according to which the event of the life-death-resurrection of Christ reveals the structure (...) and hence the meaning of history and of being. Man's appropriation of this meaning is characterized in roughly Bultmannian terms, though with somewhat more stress on the role of the Church qua social institution and on the empirically factual character of the crucial events comprising the over-all Christ-event than Bultmann lays. This essay is best regarded as another instance of the current phenomenon most notably instanced by Bishop Robinson's Honest to God and the debate it has initiated.—P. C. M. (shrink)

An instrument to assess 'ethical sensitivity' has been developed. The instrument presents four clinical vignettes and the respondent is asked to list the ethical issues related to each vignette. The responses are classified, post hoc, into the domains of autonomy, beneficence and justice. This instrument was used in 1990 to assess the ethical sensitivity of students in all four medical classes at the University of Toronto. Ethical sensitivity, as measured by this instrument, is not related to age or grade-point average. (...) Sensitivity increases between the 1st and 2nd year and then decreases throughout the rest of undergraduate medical training, such that the 4th-year students identify fewer issues than those entering medical school. Students expressing a career choice of family medicine identify more issues than their peers. Several problems with the use of the instrument and the interpretation of the data were found. Nonetheless, these findings, if reproducible, are important and their meaning needs further discussion. (shrink)