Universal turbulence on branes in holography

At a meson melting transition in holographic QCD, a weak turbulence of mesons was found with critical embeddings of probe D-branes in gravity duals. The turbulent mesons have a power-law energy distribution $\varepsilon_n \propto (\omega_n)^\alpha$ where $\omega_n$ is the mass of the $n$-th excited resonance of the meson tower. In this paper, we find that the turbulence power $\alpha$ is universal, irrespective of how the transition is driven, by numerically calculating the power in various static brane setups at criticality. We also find that the power $\alpha$ depends only on the cone dimensions of the probe D-branes.Comment: 28 pages, 16 figures, v2: a reference adde

Magnetic instability in AdS/CFT : Schwinger effect and Euler-Heisenberg Lagrangian of Supersymmetric QCD

To reveal the Schwinger effect for quarks, i.e., pair creation process of quarks and antiquarks, we derive the vacuum decay rate at strong coupling using AdS/CFT correspondence. Magnetic fields, in addition to the electric field responsible for the pair creation, causes prominent effects on the rate, and is important also in experiments such as RHIC/LHC heavy ion collisions. In this paper, through the gravity dual we obtain the full Euler-Heisenberg Lagrangian of N=2 supersymmetric QCD and study the Schwinger mechanism with not only a constant electric field but also a constant magnetic field as external fields. We determine the quark mass and temperature dependence of the Lagrangian. In sharp contrast with the zero magnetic field case, we find that the imaginary part, and thus the vacuum decay rate, diverges in the massless zero-temperature limit. This may be related to a strong instability of the QCD vacuum in strong magnetic fields. The real part of the Lagrangian serves as a generating function for non-linear electro-magnetic responses, and is found such that the Cotton-Mouton effect vanishes. Interestingly, our results of the Schwinger / Cotton-Mouton effects coincide precisely with those of N=2 supersymmetric QED.Comment: 21 pages. v2:references added, footnotes adde

The reaction of forsterite with hydrogen-its apparent and real temperature dependences

We have studied experimentally the reaction rate between solid forsterite and hydrogen gas, one of the most fundamental reactions in the solar nebula. It was found that the rate-controlling gas species was atomic hydrogen rather than molecular hydrogen, from the linear dependence of the reaction rate on P_H. The temperature dependence of the reaction rate was determined both under constant P_ and under constant P_H conditions. The former, "apparent" activation energy of the reaction was estimated to be 86.5±4.8 (2σ)kcal/mol. The latter, "real" activation energy was estimated to be 32.6±4.8 (2σ)kcal/mol. From this, a general formula that gives the true reaction rate of forsterite with hydrogen was obtained : log_(J_F/g cm^s^)=-32.6(±4.8)×10^3/2.303 RT+log_(P_H/atm)+4.00(±0.07)

Sulfuric acid as a cryofluid and oxygen isotope reservoir of planetesimals

The Sun exhibits a depletion in $^{17,18}$O relative to $^{16}$O by 6 % compared to the Earth and Moon$^{1}$. The origin of such a non-mass-dependent isotope fractionation has been extensively debated since the three-isotope-analysis$^{2}$ became available in 1970's. Self-shielding$^{3,4}$ of CO molecules against UV photons in the solar system's parent molecular cloud has been suggested as a source of the non-mass-dependent effect, in which a $^{17,18}$O-enriched oxygen was trapped by ice and selectively incorporated as water into planet-forming materials$^{5}$. The truth is that the Earth-Moon and other planetary objects deviate positively from the Sun by ~6 % in their isotopic compositions. A stunning exception is the magnetite/sulfide symplectite found in Acfer 094 meteorite, which shows 24 % enrichment in $^{17,18}$O relative to the Sun$^{6}$. Water does not explain the enrichment this high. Here we show that the SO and SO$_2$ molecules in the molecular cloud, ~106 % enriched in $^{17,18}$O relative to the Sun, evolved through the protoplanetary disk and planetesimal stages to become a sulfuric acid, 24 % enriched in $^{17,18}$O. The sulfuric acid provided a cryofluid environment in the planetesimal and by itself reacted with ferric iron to form an amorphous ferric-hydroxysulfate-hydrate, which eventually decomposed into the symplectite by shock. We indicate that the Acfer-094 symplectite and its progenitor, sulfuric acid, is strongly coupled with the material evolution in the solar system since the days of our molecular cloud.Comment: 19 pages, 3 figure

Electromagnetic instability in holographic QCD

Using the AdS/CFT correspondence, we calculate the vacuum decay rate for the Schwinger effect in confining large $N_{c}$ gauge theories. The instability is induced by the quark antiquark pair creation triggered by strong electromagnetic fields. The decay rate is obtained as the imaginary part of the Euler-Heisenberg effective Lagrangian evaluated from the D-brane action with a constant electromagnetic field in holographic QCD models such as the Sakai-Sugimoto model and the deformed Sakai-Sugimoto model. The decay rate is found to increase with the magnetic field parallel to the electric field, while it decreases with the magnetic field perpendicular to the electric field. We discuss generic features of a critical electric field as a function of the magnetic field and the QCD string tension in the Sakai-Sugimoto model.Comment: 19 pages, v2: a reference adde

Diverse features of dust particles and their aggregates inferred from experimental nanoparticles

Nanometre- to micrometre-sized solid dust particles play a vital role in star and planet formations. Despite of their importance, however, our understanding of physical and chemical properties of dust particles is still provisional. We have conducted a condensation experiment of the vapour generated from a solid starting material having nearly cosmic proportions in elements. A laser flash heating and subsequent cooling has produced a diverse type of nanoparticles simultaneously. Here we introduce four types of nanoparticles as potential dust particles in space: amorphous silicate nanoparticles (type S); core/mantle nanoparticles with iron or hydrogenised-iron core and amorphous silicate mantle (type IS); silicon oxycarbide nanoparticles and hydrogenised silicon oxycarbide nanoparticles (type SiOC); and carbon nanoparticles (type C), all produced in a single heating-cooling event. Type IS and SiOC nanoparticles are new for potential astrophysical dust. The nanoparticles are aggregated to a wide variety of structures, from compact, fluffy, and networked. A simultaneous formation of nanoparticles, which are diverse in chemistry, shape, and structure, prompts a re-evaluation of astrophysical dust particlesComment: 9 pages, 3 figure

PROGNOSTIC IMPLICATIONS OF TYPE 2 MYOCARDIAL INFARCTION IN VASOSPASTIC ANGINA: A HIGH-RISK SUBGROUP

summary:The Golomb space ${\mathbb N}_\tau$ is the set ${\mathbb N}$ of positive integers endowed with the topology $\tau$ generated by the base consisting of arithmetic progressions $\{a+ bn: n\ge 0\}$ with coprime $a,b$. We prove that the Golomb space ${\mathbb N}_\tau$ has continuum many continuous self-maps, contains a countable disjoint family of infinite closed connected subsets, the set $\Pi$ of prime numbers is a dense metrizable subspace of ${\mathbb N}_\tau$, and each homeomorphism $h$ of ${\mathbb N}_\tau$ has the following properties: $h(1)=1$, $h(\Pi)=\Pi$, $\Pi_{h(x)}=h(\Pi_x)$, and $h(x^{{\mathbb N}})=h(x)^{\,\mathbb N}$ for all $x\in{\mathbb N}$. Here $x^{\mathbb N}:=\{x^n\colon n\in{\mathbb N}\}$ and $\Pi_x$ denotes the set of prime divisors of $x$