Lagrangian subcategories and braided tensor equivalences of twisted quantum doubles of finite groups

We classify Lagrangian subcategories of the representation category of a twisted quantum double of a finite group. In view of results of 0704.0195v2 this gives a complete description of all braided tensor equivalent pairs of twisted quantum doubles of finite groups. We also establish a canonical bijection between Lagrangian subcategories of the representation category of a twisted quantum double of a finite group G and module categories over the category of twisted G-graded vector spaces such that the dual tensor category is pointed. This can be viewed as a quantum version of V. Drinfeld's characterization of homogeneous spaces of a Poisson-Lie group in terms of Lagrangian subalgebras of the double of its Lie bialgebra. As a consequence, we obtain that two group-theoretical fusion categories are weakly Morita equivalent if and only if their centers are equivalent as braided tensor categories.Comment: 26 pages; several comments and references adde

Chemical Abundances of the Typhon Stellar Stream

We present the first high-resolution chemical abundances of seven stars in the recently discovered high-energy stream Typhon. Typhon stars have apocenters >100 kpc, making this the first detailed chemical picture of the Milky Way's very distant stellar halo. Though the sample size is limited, we find that Typhon's chemical abundances are more like a dwarf galaxy than a globular cluster, showing a metallicity dispersion and no presence of multiple stellar populations. Typhon stars display enhanced $\alpha$-element abundances and increasing r-process abundances with increasing metallicity. The high-$\alpha$ abundances suggest a short star formation duration for Typhon, but this is at odds with expectations for the distant Milky Way halo and the presence of delayed r-process enrichment. If the progenitor of Typhon is indeed a new dwarf galaxy, possible scenarios explaining this apparent contradiction include a dynamical interaction that increases Typhon's orbital energy, a burst of enhanced late-time star formation that raises [$\alpha$/Fe], and/or group preprocessing by another dwarf galaxy before infall into the Milky Way. Alternatively, Typhon could be the high-energy tail of a more massive disrupted dwarf galaxy that lost energy through dynamical friction. We cannot clearly identify a known low-energy progenitor of Typhon in the Milky Way, but 70% of high-apocenter stars in cosmological simulations are from high-energy tails of large dwarf galaxies. Typhon's surprising combination of kinematics and chemistry thus underscores the need to fully characterize the dynamical history and detailed abundances of known substructures before identifying the origin of new substructures.Comment: 12 pages, 4 figures, 2 tables, accepted to MNRA

A hybrid adaptive control strategy for a smart prosthetic hand

This paper presents a hybrid of a soft computing technique of adaptive neuro-fuzzy inference system (ANFIS) and a hard computing technique of adaptive control for a two- dimensional movement of a prosthetic hand with a thumb and index finger. In articular, ANFIS is used for inverse kinematics, and the adaptive control is used for linearized dynamics to minimize tracking error. The simulations of this hybrid controller, when compared with the proportional-integral-derivative (PID) controller showed enhanced performance. Work is in progress to extend this methodology to a five-fingered, three-dimensional prosthetic hand.Peer ReviewedPostprint (published version

On the organic carbon maximum on the continental slope of the eastern Arabian Sea

The sedimentary organic carbon maximum on the continental slope off western India is widely believed to be due to the preferential preservation of deposited organic matter at water depths where the intense oxygen minimum intersects the sea floor. This region is considered to constitute one of the modern analogues for the environment of formation of organic-rich sedimentary facies that are common in the geological record. We critically examine the hypothesis that the oxygen minimum in the eastern Arabian Sea is the site of enhanced organic matter accumulation and preservation using analyses of suites of samples with wide geographical coverage along this margin. Organic carbon and nitrogen reach maximum concentrations between 200 and 1600 m depth, whereas the lowest dissolved oxygen contents in the oxygen minimum lie between 200 and 800 m depth. The Corganic/N ratios and the δ13Corganic values show that the organic matter is overwhelmingly marine, and Rock-Eval pyrolysis data demonstrate that the hydrogen indices of the sediments are similar in the sediments accumulating within and outside the oxygen minimum. Thus, the organic carbon maximum extends over a larger depth range than the oxygen minimum (as is also evident on some other slopes), and there is no evidence for preferential preservation of the organic matter within the oxygen minimum. The distribution of organic matter on the western Indian continental margin is controlled by (1) variations in supply (decreasing westward away from the centers of coastal upwelling and also decreasing with increasing water depth), (2) dilution by other sedimentary components, and (3) the texture of the sediments (coarser-grained sediments having lower carbon contents), which is controlled in turn by sediment supply and reworking. The evidence available suggests that the organic carbon maximum on this slope is not related to the position of the oxygen minimum and, consequently, that oxygen minima cannot be used to explain the distribution of organic carbon at intermediate palaeodepths in the geological record

Resolving the Metallicity Distribution of the Stellar Halo with the H3 Survey

The Galactic stellar halo is predicted to have formed at least partially from the tidal disruption of accreted dwarf galaxies. This assembly history should be detectable in the orbital and chemical properties of stars. The H3 Survey is obtaining spectra for 200,000 stars and, when combined with Gaia data, is providing detailed orbital and chemical properties of Galactic halo stars. Unlike previous surveys of the halo, the H3 target selection is based solely on magnitude and Gaia parallax; the survey therefore provides a nearly unbiased view of the entire stellar halo at high latitudes. In this paper we present the distribution of stellar metallicities as a function of Galactocentric distance and orbital properties for a sample of 4232 kinematically selected halo giants to 100 kpc. The stellar halo is relatively metal-rich, = -1.2, and there is no discernible metallicity gradient over the range 6 30 kpc, respectively. The Sagittarius stream dominates the metallicity distribution at 20-40 kpc for stars on prograde orbits. The Gaia-Enceladus merger remnant dominates the metallicity distribution for radial orbits to approximate to 30 kpc. Metal-poor stars with [Fe/H] < -2 are a small population of the halo at all distances and orbital categories. We associate the "in situ" stellar halo with stars displaying thick disk chemistry on halo-like orbits; such stars are confined to vertical bar z vertical bar < 10 kpc. The majority of the stellar halo is resolved into discrete features in chemical-orbital space, suggesting that the bulk of the stellar halo formed from the accretion and tidal disruption of dwarf galaxies. The relatively high metallicity of the halo derived in this work is a consequence of the unbiased selection function of halo stars and, in combination with the recent upward revision of the total stellar halo mass, implies a Galactic halo metallicity that is typical for its mass.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Small Quadrupole Deformation for the Dipole Bands in 112In

High spin states in $^{112}$In were investigated using $^{100}$Mo($^{16}$O, p3n) reaction at 80 MeV. The excited level have been observed up to 5.6 MeV excitation energy and spin $\sim$ 20$\hbar$ with the level scheme showing three dipole bands. The polarization and lifetime measurements were carried out for the dipole bands. Tilted axis cranking model calculations were performed for different quasi-particle configurations of this doubly odd nucleus. Comparison of the calculations of the model with the B(M1) transition strengths of the positive and negative parity bands firmly established their configurations.Comment: 10 pages, 11 figures, 2 table