Chiral zero modes of the SU(n) Wess-Zumino-Novikov-Witten model

We define the chiral zero modes' phase space of the G=SU(n) Wess-Zumino-Novikov-Witten model as an (n-1)(n+2)-dimensional manifold M_q equipped with a symplectic form involving a special 2-form - the Wess-Zumino (WZ) term - which depends on the monodromy M. This classical system exhibits a Poisson-Lie symmetry that evolves upon quantization into an U_q(sl_n) symmetry for q a primitive even root of 1. For each constant solution of the classical Yang-Baxter equation we write down explicitly a corresponding WZ term and invert the symplectic form thus computing the Poisson bivector of the system. The resulting Poisson brackets appear as the classical counterpart of the exchange relations of the quantum matrix algebra studied previously. We argue that it is advantageous to equate the determinant D of the zero modes' matrix to a pseudoinvariant under permutations q-polynomial in the SU(n) weights, rather than to adopt the familiar convention D=1.Comment: 30 pages, LaTeX, uses amsfonts; v.2 - small corrections, Appendix and a reference added; v.3 - amended version for J. Phys.

Modelling background charge rearrangements near single-electron transistors as a Poisson process

Background charge rearrangements in metallic single-electron transistors are modelled in two-level tunnelling systems as a Poisson process with a scale parameter as only variable. The model explains the recent observation of asymmetric Coulomb blockade peak spacing distributions in metallic single-electron transistors. From the scale parameter we estimate the average size of the tunnelling systems, their density of states, and the height of their energy barrier. We conclude that the observed background charge rearrangements predominantly take place in the substrate of the single-electron transistor.Comment: 7 pages, 2 eps figures, used epl.cls macro include

Built Form and Culture: Italian Transnational Houses in Australia

Accordingly to Wagner, “Dwellings stand as the concrete expressions of a complex interaction among cultural skills and norms, climatic conditions and the potentialities of natural materials”. This study, beginning with an enquiry into the way trans-national houses are the physical expression of interacting cultural factors, provides a theoretical framework grounded on cross-cultural studies for understanding the way cultural needs have influenced the form of the archetypal post WWII ‘house on a quarter-acre block’ built in Brisbane by Italian migrants. The findings reveal that while the architectural form of the Italian Trans-national houses built in Brisbane is influenced by the need to continue architectural cultural traditions in the host country, the spatial distribution of the artifact was influenced by socio-cultural factors and urban fabric, from both the native and hosting built environment, in the attempt of re-establishing and enhancing the native way of life

Effect of cylinder power and axis changes on vision in astigmatic participants: A comment [letter]

Dear editor We read with interest the article by Sha et al1 in the March 2019 issue. This study evaluated the effects of misalignment axis and undercorrecting cylinder powers on the visual performance of astigmatic people. The aim of this work was mainly to assist eye-care practitioners in reducing the number of toric contact lenses stock-keeping units. The authors analyze the effect of astigmatic undercorrection by 0.25, 0.50 and 0.75 DC, at different amounts of misalignments up to 30°. In this analysis, the effects of cylinder power, cylinder axis and their mutual interaction are analyzed separately. However, it is well known that cylinder power and axis are not independent variables; in fact, astigmatism is a vector magnitude. Several studies2, 4 use vector formalism to quantify the blur strength produced by astigmatism. Even in previous literature, 1 the authors show the power vector components (M, J0, J45) in Table 1, for the different groups in which the sample is divided. ..

Chiral Quantization of the WZW SU(n)SU(n) Model

We quantize the $SU(n)$ Wess-Zumino-Witten model in terms of left and right chiral variables choosing an appropriate gauge and we compare our results with the results that have been previously obtained in the algebraic treatment of the problem. The algebra of the chiral vertex operators in the fundamental representation is verified by solving appropriate Knizhnik-Zamolodchikov equations.Comment: 35 pages, latex, no figures, corrections in the chiral decomposition of the vertex operators in the WZW model are introduce

The Herschel Orion protostar survey: spectral energy distributions and fits using a grid of protostellar models

Furlan, E. et. al.We present key results from the Herschel Orion Protostar Survey: spectral energy distributions (SEDs) and model fits of 330 young stellar objects, predominantly protostars, in the Orion molecular clouds. This is the largest sample of protostars studied in a single, nearby star formation complex. With near-infrared photometry from 2MASS, mid and far-infrared data from Spitzer and Herschel, and submillimeter photometry from APEX, our SEDs cover 1.2-870 mu m and sample the peak of the protostellar envelope emission at similar to 100 mu m. Using mid-IR spectral indices and bolometric temperatures, we classify our sample into 92 Class 0 protostars, 125 Class I protostars, 102 flat spectrum sources, and 11 Class II pre-main-sequence stars. We implement a simple protostellar model (including a disk in an infalling envelope with outflow cavities) to generate a grid of 30,400 model SEDs and use it to determine the best-fit model parameters for each protostar. We argue that far-IR data are essential for accurate constraints on protostellar envelope properties. We find that most protostars, and in particular the flat-spectrum sources, are well fit. The median envelope density and median inclination angle decrease from Class 0 to Class I to flat spectrum protostars, despite the broad range in best-fit parameters in each of the three categories. We also discuss degeneracies in our model parameters. Our results confirm that the different protostellar classes generally correspond to an evolutionary sequence with a decreasing envelope infall rate, but the inclination angle also plays a role in the appearance, and thus interpretation, of the SEDs.The work of W.J.F. was supported in part by an appointment to the NASA Postdoctoral Program at Goddard Space Flight Center, administered by Oak Ridge Associated Universities through a contract with NASA. J.J.T. acknowledges support provided by NASA through Hubble Fellowship grant #HST-HF-51300.01-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. J.J.T. acknowledges further support from grant 639.041.439 from the Netherlands Organisation for Scientific Research (NWO). The work of A.M.S. was supported by the Deutsche Forschungsgemeinschaft priority program 1573 ("Physics of the Interstellar Medium"). M.O. acknowledges support from MINECO (Spain) AYA2011-30228-CO3-01 and AYA2014-57369-C3-3-P grants (co-funded with FEDER funds)Peer reviewe

Caspase-independent programmed cell death triggers Ca2PO4 deposition in an in vitro model of nephrocalcinosis

We provide evidence of caspase-independent cell death triggering the calcification process in GDNF-silenced HK-2 cells

Near-Infrared, Adaptive Optics Observations of the T Tauri Multiple-Star System

With high-angular-resolution, near-infrared observations of the young stellar object T Tauri at the end of 2002, we show that, contrary to previous reports, none of the three infrared components of T Tau coincide with the compact radio source that has apparently been ejected recently from the system (Loinard, Rodriguez, and Rodriguez 2003). The compact radio source and one of the three infrared objects, T Tau Sb, have distinct paths that depart from orbital or uniform motion between 1997 and 2000, perhaps indicating that their interaction led to the ejection of the radio source. The path that T Tau Sb took between 1997 and 2003 may indicate that this star is still bound to the presumably more massive southern component, T Tau Sa. The radio source is absent from our near-infrared images and must therefore be fainter than K = 10.2 (if located within 100 mas of T Tau Sb, as the radio data would imply), still consistent with an identity as a low-mass star or substellar object.Comment: 11 pages, 3 figures, submitted to ApJ

Coulomb oscillations in three-layer graphene nanostructures

We present transport measurements on a tunable three-layer graphene single electron transistor (SET). The device consists of an etched three-layer graphene flake with two narrow constrictions separating the island from source and drain contacts. Three lateral graphene gates are used to electrostatically tune the device. An individual three-layer graphene constriction has been investigated separately showing a transport gap near the charge neutrality point. The graphene tunneling barriers show a strongly nonmonotonic coupling as function of gate voltage indicating the presence of localized states in the constrictions. We show Coulomb oscillations and Coulomb diamond measurements proving the functionality of the graphene SET. A charging energy of $\approx 0.6$ meV is extracted.Comment: 10 pages, 6 figure