303 research outputs found
Flowing to four dimensions
We analyze the properties of a model with four-dimensional brane-localized
Higgs type potential of a six dimensional scalar field satisfying the Dirichlet
boundary condition on the boundary of a transverse two-dimensional compact
space. The regularization of the localized couplings generates classical
renormalization group running. A tachyonic mass parameter grows in the
infrared, in analogy with the QCD gauge coupling in four dimensions. We find a
phase transition at a critical value of the bare mass parameter such that the
running mass parameter becomes large in the infrared precisely at the
compactification scale. Below the critical coupling, the theory is in symmetric
phase, whereas above it spontaneous symmetry breaking occurs. Close to the
phase transition point there is a very light mode in the spectrum. The massive
Kaluza-Klein spectrum at the critical coupling becomes independent of the UV
cutoff.Comment: 22 pages, LaTe
Problems with Using Evolutionary Theory in Philosophy
Does science move toward truths? Are present scientific theories (approximately) true? Should we invoke truths to explain the success of science? Do our cognitive faculties track truths? Some philosophers say yes, while others say no, to these questions. Interestingly, both groups use the same scientific theory, viz., evolutionary theory, to defend their positions. I argue that it begs the question for the former group to do so because their positive answers imply that evolutionary theory is warranted, whereas it is self-defeating for the latter group to do so because their negative answers imply that evolutionary theory is unwarranted
Finite temperature behaviour of the ISS-uplifted KKLT model
We study the static phase structure of the ISS-KKLT model for moduli
stabilisation and uplifting to a zero cosmological constant. Since the
supersymmetry breaking sector and the moduli sector are only gravitationally
coupled, we expect negligible quantum effects of the modulus upon the ISS
sector, and the other way around. Under this assumption, we show that the ISS
fields end up in the metastable vacua. The reason is not only that it is
thermally favoured (second order phase transition) compared to the phase
transition towards the supersymmetric vacua, but rather that the metastable
vacua form before the supersymmetric ones. This nice feature is exclusively due
to the presence of the KKLT sector. We also show that supergravity effects are
negligible around the origin of the field space. Finally, we turn to the
modulus sector and show that there is no destabilisation effect coming from the
ISS sector.Comment: 23 pages, 3 figures, mistake corrected, one plot updated, physical
conclusions unchange
Desperate housewives: An analysis of the characterisations of female gamblers portrayed in gambling movies in Hong Kong
This article examines portrayals of female gamblers in recent Hong Kong movies. The authors report that the depiction of female gamblers is very different from that of male gamblers in the movies made in the same period. Whereas the male gamblers are pitching a lonely and desperate battle against the evil opponent, the female gamblers portrayed in the movies are housewives or small-time players who gamble only for their personal gain. A general negative overtone in portrayals of female gamblers was interpreted as a reflection of the traditional view that discourages women from gambling. The shift of gambling themes in the Hong Kong movies has been identified to reflect the most salient concerns among Hong Kong residents. Such changes are attributed to particular social and cultural changes in the community
The Relationship Between Belief and Credence
Sometimes epistemologists theorize about belief, a tripartite attitude on which one can believe, withhold belief, or disbelieve a proposition. In other cases, epistemologists theorize about credence, a fine-grained attitude that represents one’s subjective probability or confidence level toward a proposition. How do these two attitudes relate to each other? This article explores the relationship between belief and credence in two categories: descriptive and normative. It then explains the broader significance of the belief-credence connection and concludes with general lessons from the debate thus far
Evidence for early life in Earth’s oldest hydrothermal vent precipitates
Although it is not known when or where life on Earth began, some of the earliest habitable environments may have been submarine-hydrothermal vents. Here we describe putative fossilized microorganisms that are at least 3,770 million and possibly 4,280 million years old in ferruginous sedimentary rocks, interpreted as seafloor-hydrothermal vent-related precipitates, from the Nuvvuagittuq belt in Quebec, Canada. These structures occur as micrometre-scale haematite tubes and filaments with morphologies and mineral assemblages similar to those of filamentous microorganisms from modern hydrothermal vent precipitates and analogous microfossils in younger rocks. The Nuvvuagittuq rocks contain isotopically light carbon in carbonate and carbonaceous material, which occurs as graphitic inclusions in diagenetic carbonate rosettes, apatite blades intergrown among carbonate rosettes and magnetite–haematite granules, and is associated with carbonate in direct contact with the putative microfossils. Collectively, these observations are consistent with an oxidized biomass and provide evidence for biological activity in submarine-hydrothermal environments more than 3,770 million years ago
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Needs and opportunities in mineral evolution research
Progress in understanding mineral evolution, Earth’s changing near-surface mineralogy through time, depends on the availability of detailed information on mineral localities of known ages and geologic settings. A comprehensive database including this information, employing the mindat.org web site as a platform, is now being implemented. This resource will incorporate software to correlate a range of mineral occurrences and properties vs. time, and it will thus facilitate studies of the chang- ing diversity, distribution, associations, and characteristics of individual minerals as well as mineral groups. The Mineral Evolution Database thus holds the prospect of revealing mineralogical records of important geophysical, geochemical, and biological events in Earth history.Organismic and Evolutionary Biolog
Metabolically diverse primordial microbial communities in Earth’s oldest seafloor-hydrothermal jasper
The oldest putative fossils occur as hematite filaments and tubes in jasper-carbonate banded iron formations from the 4280- to 3750-Ma Nuvvuagittuq Supracrustal Belt, Québec. If biological in origin, these filaments might have affinities with modern descendants; however, if abiotic, they could indicate complex prebiotic forms on early Earth. Here, we report images of centimeter-size, autochthonous hematite filaments that are pectinate-branching, parallel-aligned, undulated, and containing Fe2+-oxides. These microstructures are considered microfossils because of their mineral associations and resemblance to younger microfossils, modern Fe-bacteria from hydrothermal environments, and the experimental products of heated Fe-oxidizing bacteria. Additional clusters of irregular hematite ellipsoids could reflect abiotic processes of silicification, producing similar structures and thus yielding an uncertain origin. Millimeter-sized chalcopyrite grains within the jasper-carbonate rocks have 34S- and 33S-enrichments consistent with microbial S-disproportionation and an O2-poor atmosphere. Collectively, the observations suggest a diverse microbial ecosystem on the primordial Earth that may be common on other planetary bodies, including Mars
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