N=1 Non-Abelian Tensor Multiplet in Four Dimensions

We carry out the N=1 supersymmetrization of a physical non-Abelian tensor with non-trivial consistent couplings in four dimensions. Our system has three multiplets: (i) The usual non-Abelian vector multiplet (VM) (A_\mu{}^I, \lambda^I), (ii) A non-Abelian tensor multiplet (TM) (B_{\mu\nu}{}^I, \chi^I, \varphi^I), and (iii) A compensator vector multiplet (CVM) (C_\mu{}^I, \rho^I). All of these multiplets are in the adjoint representation of a non-Abelian group G. Unlike topological theory, all of our fields are propagating with kinetic terms. The C_\mu{}^I-field plays the role of a Stueckelberg compensator absorbed into the longitudinal component of B_{\mu\nu}{}^I. We give not only the component lagrangian, but also a corresponding superspace reformulation, reconfirming the total consistency of the system. The adjoint representation of the TM and CVM is further generalized to an arbitrary real representation of general SO(N) gauge group. We also couple the globally N=1 supersymmetric system to supergravity, as an additional non-trivial confirmation.Comment: 18 pages, no figur

NMR analysis of the dynamic exchange of the NS2B cofactor between open and closed conformations of the West Nile Virus NS2B-NS3 protease

BACKGROUND The two-component NS2B-NS3 proteases of West Nile and dengue viruses are essential for viral replication and established targets for drug development. In all crystal structures of the proteases to date, the NS2B cofactor is located far from the substrate binding site (open conformation) in the absence of inhibitor and lining the substrate binding site (closed conformation) in the presence of an inhibitor. METHODS In this work, nuclear magnetic resonance (NMR) spectroscopy of isotope and spin-labeled samples of the West Nile virus protease was used to investigate the occurrence of equilibria between open and closed conformations in solution. FINDINGS In solution, the closed form of the West Nile virus protease is the predominant conformation irrespective of the presence or absence of inhibitors. Nonetheless, dissociation of the C-terminal part of the NS2B cofactor from the NS3 protease (open conformation) occurs in both the presence and the absence of inhibitors. Low-molecular-weight inhibitors can shift the conformational exchange equilibria so that over 90% of the West Nile virus protease molecules assume the closed conformation. The West Nile virus protease differs from the dengue virus protease, where the open conformation is the predominant form in the absence of inhibitors. CONCLUSION Partial dissociation of NS2B from NS3 has implications for the way in which the NS3 protease can be positioned with respect to the host cell membrane when NS2B is membrane associated via N- and C-terminal segments present in the polyprotein. In the case of the West Nile virus protease, discovery of low-molecular-weight inhibitors that act by breaking the association of the NS2B cofactor with the NS3 protease is impeded by the natural affinity of the cofactor to the NS3 protease. The same strategy can be more successful in the case of the dengue virus NS2B-NS3 protease.The project was funded by the Australian Research Council (http://www.arc.gov.au), grant DP0877540

Dilaton and Second-Rank Tensor Fields as Supersymmetric Compensators

We formulate a supersymmetric theory in which both a dilaton and a second-rank tensor play roles of compensators. The basic off-shell multiplets are a linear multiplet (B_{\mu\nu}, \chi, \phi) and a vector multiplet (A_\mu, \l; C_{\mu\nu\rho}), where \phi and B_{\m\n} are respectively a dilaton and a second-rank tensor. The third-rank tensor C_{\mu\nu\rho} in the vector multiplet is 'dual' to the conventional D-field with 0 on-shell or 1 off-shell degree of freedom. The dilaton \phi is absorbed into one longitudinal component of A_\mu, making it massive. Initially, B_{\mu\nu} has 1 on-shell or 3 off-shell degrees of freedom, but it is absorbed into the longitudinal components of C_{\mu\nu\rho}. Eventually, C_{\mu\nu\rho} with 0 on-shell or 1 off-shell degree of freedom acquires in total 1 on-shell or 4 off-shell degrees of freedom, turning into a propagating massive field. These basic multiplets are also coupled to chiral multiplets and a supersymmetric Dirac-Born-Infeld action. Some of these results are also reformulated in superspace. The proposed mechanism may well provide a solution to the long-standing puzzle of massless dilatons and second-rank tensors in supersymmetric models inspired by string theory.Comment: 15 pages, no figure

Effect of natural convection on oscillating flow in a pipe with cryogenic temperature difference across the ends

The effect of natural convection on the oscillatory flow in an open-ended pipe driven by a timewise sinusoidally varying pressure at one end and subjected to an ambient-to-cryogenic temperature difference across the ends, is numerically studied. Conjugate effects arising out of the interaction of oscillatory flow with heat conduction in the pipe wall are taken into account by considering a finite thickness wall with an insulated exterior surface. Two cases, namely, one with natural convection acting downwards and the other, with natural convection acting upwards, are considered. The full set of compressible flow equations with axissymmetry are solved using a pressure correction algorithm. Parametric studies are conducted with frequencies in the range 5–15 Hz for an end-to-end temperature difference of 200 and 50 K. Results are obtained for the variation of velocity, temperature, Nusselt number and the phase relationship between mass flow rate and temperature. It is found that the Rayleigh number has a minimal effect on the time averaged Nusselt number and phase angle. However, it does influence the local variation of velocity and Nusselt number over one cycle. The natural convection and pressure amplitude have influence on the energy flow through the gas and solid

Implication of Compensator Field and Local Scale Invariance in the Standard Model

We introduce Weyl's scale symmetry into the standard model (SM) as a local symmetry. This necessarily introduces gravitational interactions in addition to the local scale invariance group \tilde U(1) and the SM groups SU(3) X SU(2) X U(1). The only other new ingredients are a new scalar field \sigma and the gauge field for \tilde U(1) we call the Weylon. A noteworthy feature is that the system admits the St\" uckelberg-type compensator. The \sigma couples to the scalar curvature as (-\zeta/2) \sigma^2 R, and is in turn related to a St\" uckelberg-type compensator \varphi by \sigma \equiv M_P e^{-\varphi/M_P} with the Planck mass M_P. The particular gauge \varphi = 0 in the St\" uckelberg formalism corresponds to \sigma = M_P, and the Hilbert action is induced automatically. In this sense, our model presents yet another mechanism for breaking scale invariance at the classical level. We show that our model naturally accommodates the chaotic inflation scenario with no extra field.Comment: This work is to be read in conjunction with our recent comments hep-th/0702080, arXiv:0704.1836 [hep-ph] and arXiv:0712.2487 [hep-ph]. The necessary ingredients for describing chaotic inflation in the SM as entertained by Bezrukov and Shaposhnikov [17] have been provided by our original model [8]. We regret their omission in citing our original model [8

CFD analysis of high frequency miniature pulse tube refrigerators for space applications with thermal non-equilibrium model

High frequency, miniature, pulse tube cryocoolers are extensively used in space applications because of their simplicity. Parametric studies of inertance type pulse tube cooler are performed with different length-to-diameter ratios of the pulse tube with the help of the FLUENT® package. The local thermal non-equilibrium of the gas and the matrix is taken into account for the modeling of porous zones, in addition to the wall thickness of the components. Dynamic characteristics and the actual mechanism of energy transfer in pulse are examined with the help of the pulse tube wall time constant. The heat interaction between pulse tube wall and the oscillating gas, leading to surface heat pumping, is quantified. The axial heat conduction is found to reduce the performance of the pulse tube refrigerator. The thermal non-equilibrium predicts a higher cold heat exchanger temperature compared to thermal equilibrium. The pressure drop through the porous medium has a strong non-linear effect due to the dominating influence of Forchheimer term over that of the linear Darcy term at high operating frequencies. The phase angle relationships among the pressure, temperature and the mass flow rate in the porous zones are also important in determining the performance of pulse tube refrigerator