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

Experimental evidence for abiotic formation of low-temperature proto-dolomite facilitated by clay minerals

The origin of sedimentary dolomite is a subject of long-standing enigma that still awaits resolution. Previous studies have shown that room temperature synthesis of abiotic dolomite is rarely achieved and primary (proto-)dolomite precipitation is closely associated with microbial activities. In this study, we demonstrate through laboratory carbonation experiments that highly negative-charged clay minerals (as indicated by the values of zetal potential) such as illite and montmorillonite can aid the precipitation of abiotic proto-dolomite under ambient conditions, whereas nearly-neutral charged kaolinite exerts negligible influence on such process. In comparison to montmorillonite, illite has higher surface-charge density, thus is more effective in catalyzing proto-dolomite precipitation. Furthermore, the signal of proto-dolomite in carbonate neoformations is enhanced with increasing concentrations of illite or montmorillonite. On the basis of these results, we suggest that clay minerals catalyze dolomite formation perhaps via electrostatic binding of Mg2+ and Ca2+ ions and simultaneous desolvation of these strongly hydrated cations, a crucial step for dolomite crystallization. The resulting proto-dolomites display the morphologies, textures, and structures similar to those of biogenic dolomite reported before, which are considered precursors of ordered sedimentary dolomite. Therefore, our results offer a possible route to authigenic dolomite found in sedimentary environments

Catalytic effect of microbially-derived carboxylic acids on the precipitation of Mg-calcite and disordered dolomite: Implications for sedimentary dolomite formation

The genesis of dolomite is a contentious issue partly due to the difficulty in its synthesis at ambient temperature. Certain types of microorganisms have been demonstrated to be effective in promoting the precipitation of disordered dolomite, an important precursor of sedimentary ordered dolomite. In contrast to a growing body of research on the catalytic role of microbial exopolymers in the crystallization of disordered dolomite, the role of other microbial exudates (e.g., carboxylic acids) remains unknown. To fill in this knowledge gap, precipitation experiments, mimicking the carbonation process within microbial mats, were conducted in saline solutions containing 0-30 mM succinic acid or citric acid, which are commonly produced by microbes. The starting salinities of experiment solutions were set to 35‰ and 70‰, in order to evaluate the effect of solution salinity on dolomite formation. Our results showed that both succinic acid and citric acid enhanced the incorporation of Mg2+ into growing Ca-Mg carbonates. Solution salinity also played a positive role in enhancing Mg signature in Ca-Mg carbonates. Disordered dolomite with 40.92 mol% MgCO3 was detected under the conditions of 30 mM succinic acid and 70‰ salinity, whereas in other reactors with succinic acid, Mg-calcites formed. Citric acid was more effective in loading Mg2+ into Ca-Mg carbonates compared with succinic acid, as evidenced by the predominant occurrence of disordered dolomite with MgCO3 content ranging from 40.91 mol% to 46.75 mol% in most conditions tested. The results of this study have implications for the formation mechanism of sedimentary dolomite

Supersymmetry and R-symmetry breaking in models with non-canonical Kahler potential

We analyze several aspects of R-symmetry and supersymmetry breaking in generalized O'Raifeartaigh models with non-canonical Kahler potential. Some conditions on the Kahler potential are derived in order for the non-supersymmetric vacua to be degenerate. We calculate the Coleman-Weinberg (CW) effective potential for general quiral non-linear sigma models and then study the 1-loop quantum corrections to the pseudo-moduli space. For R-symmetric models, the quadratic dependence of the CW potential with the ultraviolet cutoff scale disappears. We also show that the conditions for R-symmetry breaking are independent of this scale and remain unchanged with respect to those of canonical models. This is, R-symmetry can be broken when generic R-charge assignments to the fields are made, while it remains unbroken when only fields with R-charge 0 and 2 are present. We further show that these models can keep the runaway behavior of their canonical counterparts and also new runaway directions can be induced. Due to the runaway directions, the non-supersymmetric vacua is metastable.Comment: 19 pages, revised version with minor changes, references added, published in JHE

The catalytic role of planktonic aerobic heterotrophic bacteria in protodolomite formation: Results from Lake Jibuhulangtu Nuur, Inner Mongolia, China

Dolomite nucleation and subsequent crystallization are kinetically-controlled processes. Modern dolomite-forming environments provide clues to the trigger factors that facilitate dolomite formation under Earth surface conditions. It has been documented that certain types of benthic microorganisms promoted the precipitation of protodolomite from sediment pore waters. As protodolomite is thought to be a possible precursor of sedimentary ordered dolomite, microbial mediation has thus been suggested as one interpretation of the occurrence of dolomite in modern sediments. To date, however, it is still unclear whether planktonic microorganisms could directly initiate protodolomite crystallization in the upper water column of present dolomite depositing environments. In this study, we report on the occurrence of authigenic protodolomite in the upmost sediments of a high-sulfate, Chinese inland saline lake (Lake Jibuhulangtu Nuur). This lake was therefore considered to be a natural laboratory to test the catalytic effect of planktonic aerobic heterotrophic bacteria on protodolomite formation. Laboratory mineralization experiments were conducted in a liquid medium that mimicked the ion concentrations and pH condition of lake surface water. The incubation experiments showed that aragonite formed in the abiotic systems, while protodolomite predominantly occurred in the bioreactors using either an enrichment culture or pure isolates of aerobic heterotrophic and halophilic bacteria from lake water. The resulting microbially-induced protodolomite crystals displayed spherical morphology and had MgCO3 composition ranging from 42.7 mol% to 47.1 mol%. These protodolomite spherulites were formed by aggregation of randomly-distributed nano-crystals. Compared to synthetic abiotic protodolomite, microbially-induced protodolomite contained considerable amounts of organic matter, which might occur as intracrystalline inclusion or was located between nano-crystals of protodolomite spherulite. Our results support the emerging view that dissolved sulfate is not an inhibitor for the formation of low-temperature (proto-)dolomite. The presence of organic matter intimately associated with dolomite crystals may serve as a hallmark indicative of a biotically induced origin for some types of dolomite

Precipitation of protodolomite facilitated by sulfate-reducing bacteria: The role of capsule extracellular polymeric substances

The origin of dolomite has long puzzled geologists. It has recently been documented that sulfate-reducing bacteria (SRB) are capable of catalyzing the formation of protodolomite, a previously proposed precursor of ordered sedimentary dolomite. However, the catalytic mechanism of SRB remains incompletely understood. This experimental study is aimed at probing the effect of capsule extracellular polymeric substances (capsule EPS) from SRB on the crystallization of protodolomite in vivo. The capsule EPS tested herein was isolated from a protodolomite-mediating SRB, Desulfotomaculum ruminis, and added into a solution wherein the degree of oversaturation was close to the growth medium of D. ruminis at stationary phase. The solid products were characterized with X-ray diffraction (XRD), Raman spectroscopy and, scanning and transmission electron microscopy (SEM and TEM). Our results indicated that aragonite emerged in the reactors without capsule EPS, while Ca-Mg carbonates (Mg-calcite and protodolomite) were produced in the systems amended with capsule EPS. The incorporation amount of Mg2+ in Ca-Mg carbonates was enhanced with the increasing concentration of capsule EPS. The predominant occurrence of protodolomite was found in the reactor with 140 mg/L capsule EPS. These resulting protodolomites were spherical in shape, and composed of numerous nano-particles. The catalytic influence of capsule EPS on the precipitation of protodolomite might be attributed to their strong Mg2+ binding capacity, potentially diminishing Mg-hydration, which is a potent inhibitor of protodolomite crystallization. The results of Fourier transformation infrared (FT-IR) spectra showed that Mg2+ was bonded with carboxyl and hydroxyl groups on capsule EPS. This inferred adsorption capacity of capsule EPS was also supported by new calculations of complexation chemistry between Mg-H2O complex and organic compounds present in capsule EPS

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

Can the evolution of music be analyzed in a quantitative manner?

We propose a methodology to study music development by applying multivariate statistics on composers characteristics. Seven representative composers were considered in terms of eight main musical features. Grades were assigned to each characteristic and their correlations were analyzed. A bootstrap method was applied to simulate hundreds of artificial composers influenced by the seven representatives chosen. Afterwards we quantify non-numeric relations like dialectics, opposition and innovation. Composers differences on style and technique were represented as geometrical distances in the feature space, making it possible to quantify, for example, how much Bach and Stockhausen differ from other composers or how much Beethoven influenced Brahms. In addition, we compared the results with a prior investigation on philosophy. Opposition, strong on philosophy, was not remarkable on music. Supporting an observation already considered by music theorists, strong influences were identified between composers by the quantification of dialectics, implying inheritance and suggesting a stronger master-disciple evolution when compared to the philosophy analysis.Comment: 8 pages, 6 figures, added references for sections 1 and 4.C, better mathematical description on section 2. New values and interpretation, now considering a bootstrap metho

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