We explain a method for computing the bulk viscosity of strongly coupled thermal plasmas dual to supergravity backgrounds supported by one scalar field. Whereas earlier investigations required the computation of the leading dissipative term in the dispersion relation for sound waves, our method requires only the leading frequency dependence of an appropriate Green's function in the low-frequency limit. With a scalar potential chosen to mimic the equation of state of QCD, we observe a slight violation of the lower bound on the ratio of the bulk and shear viscosities conjectured in [1]. R 3,1 ii h / ϕ horizon t,x z z = z Figure 1: A cartoon of the relation between shear viscosity and h 12 graviton absorption, and between bulk viscosity and absorption of a mixture of the h ii graviton and the scalar φ.as explored for example in [11,12]. Earlier works [4 -8, 1] have focused on calculating the leading dissipative term in the dispersion relation for sound waves. We instead appeal directly to a Kubo formula. Our computation comes down to understanding the bulk propagation of some linear superposition of gravitons and scalar perturbations. The strategy, as illustrated in figure 1, is to start with an infinite, static, thermal background, linearize the equations of motion around it, and solve these linearized equations in some appropriate approximation. A large-wavelength, low-frequency approximation is the appropriate one because ζ describes an effect in hydrodynamics, which is to say the infrared approximation to the dynamics. The absorption probability of low-energy quanta is proportional to ζ. This is entirely analogous to the well-known computation of shear viscosity [13], but more technically involved because of the mixing between the scalar and metric perturbations. We can decouple these perturbations through a judicious choice of gauge, namely the gauge where the value of the scalar is used as a radial variable. In this gauge, we need only solve a single ordinary differential equation, given in equation (2.9a). The bulk viscosity to shear viscosity ratio can then be extracted from the solution of (2.9a) by using equation (2.41), which is our main result. In examples, a conjectured bound [1] on the ratio ζ/η of bulk to shear viscosity is observed to be satisfied in most but not all circumstances.The structure of the rest of this paper is as follows. In section 2 we explain our method for computing the bulk viscosity from AdS/CFT. Section 2.1 summarizes the relevant gravitational backgrounds. Section 2.2 shows how to perturb the backgrounds in a rotationally invariant fashion. Section 2.3 reviews the treatment of metric perturbations that control the shear viscosity, explaining in particular how to extract the imaginary part of the retarded Green's function of an off-diagonal component T 12 of the gauge theory stress tensor. Section 2.4 adapts this treatment to the case of bulk viscosity, using equations derived in section 2.2. Section 2.5 detours once again to a review of the shear viscosity computation, showing ho...
ABSTRACT-Although possible usefulness of non-selective monoamine oxidase (MAO) inhibitors for Parkinson's disease therapy has been suggested in the literature, MAO inhibitors whose inhibition is reversible and have dual action to both MAO-A and -B subtypes is not available yet. Subtype selectivity and reversibility of a series of novel MAO inhibitors, 3-(2-aminoethoxy)-1,2-benzisoxazole derivatives, were studied. Several dual MAO inhibitors, which inhibit both MAO-A and -B, were obtained. When administered to mice, their effects were generally reversible. Among the derivatives, RS-1636 and RS-1653 had much longer duration of brain MAO-B inhibition than that of MAO-A. In vitro, the inhibited MAO-A activity by these compounds was partially recovered by buffer change at 4°C, while little MAO-B activity was recovered. Although it is not fully elucidated yet, the reversibility of these inhibitors is probably determined primarily by this dissociation profile. This unique differential reversibility indicates that optimization of the balance of actions can be achieved by differentiating reversibility to each target molecule.Keywords: Monoamine oxidase, Tight-binding inhibitor, Reversibility, Parkinson's disease Monoamine oxidase (MAO, EC 1.4.3.4) inhibitors were discovered by their effect on mood disorders in the 1950s (1, 2), and have been used as antidepressants since then. Two isozymes, MAO-A and MAO-B have been identified (1, 2). MAO-A is selectively inhibited by clorgyline and preferentially deaminates serotonin (5-HT) and noradrenaline (NA). MAO-B is selectively inhibited by l-deprenyl and preferentially deaminates 2-phenylethylamine (PEA) and benzylamine. Recently, marked advances have been made in the understanding of selective binding of substrates with MAO (3, 4). The old generation of MAO inhibitors, such as isocarboxazid, phenelzine and tranylcypromine, inhibit both A and B isozymes irreversibly. Several inhibitors selective to only MAO-A or MAO-B, with both reversible and irreversible characteristics, were developed later. Clorgyline, moclobemide (2), brofaromine (5), toloxatone and RS-8359 (6, 7) are some such MAO-A selective inhibitors that are strong antidepressants. lDeprenyl (selegiline) (8), rasagiline, MDL-72974 and lazabemide (9) are some such selective inhibitors to MAO-B that have a mild anti-Parkinsonian effect. However, potential usefulness of reversible MAO inhibitors that have dual action to both MAO-A and MAO-B (10) have not been verified yet.In this paper, a new family of MAO inhibitors, 3-(2-aminoethoxy)-1,2-benzisoxazole derivatives, is presented. Several reversible MAO inhibitors to both MAO-A and -B were obtained. Among the reversible dual inhibitors, RS-1636 and RS-1653 had much longer duration of MAO-B inhibition than that of MAO-A. The profile of MAO inhibition in vitro was studied to verify the mechanism of this differential reversibility. MATERIALS AND METHODS AnimalsMale C57BL/6 mice (5 -7 week-old, 18 -22 g body weight, from Charles River, Tokyo), which are widely used in rodent m...
4 h s 1 1 m -I n this paper. we propose a circular polarized antenna, which is one-wavelength L-shaped structure with one feed point. l h r proposed antenna is composed of two elements, which have cliglitl! different length. and the feed point is arranged on the coiner point. The length of the two elements i s adjusted and the circular polarization characteristics are calculated by using the inioment mcthod. As a result. we make clear the principle of the proposed antenna that the circular polarization can be obtained 11) iid,jurting design parameters so that the phase difference of r\citation currents on the two elements is in agreement with the included angle between the two elements. Moreover, w'e make an nperiment o n a fabricated slot type model of the proposed antenna and demonstrated its favorable impedance matching characteristic. The L-shaped and simple feeding structure of the proposed antenna is suited to be built i n the corner of front panel of sniail radio equipment for wireless LAN systems. lie?ivords: mfrcnmt, circtclar puliiri:ntion. ivire1es.c LAN
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