Shape Function Effects in B -> X_c l \nu_l

Owing to the fact that m_c^2 ~ m_b \Lambda_QCD, the endpoint region of the charged lepton energy spectrum in the inclusive decay B -> X_c l \nu_l is affected by the Fermi motion of the initial-state b quark bound in the B meson. This effect is described in QCD by shape functions. Including the mass of the final-state quark, we find that a different set of operators as employed in Ref. hep-ph/0205150 is needed for a consistent matching, when incorporating the subleading contributions in B -> X_q l \nu_l for both q = u and q = c. In addition, we modify the usual twist expansion in such a way that it yields a description of the lepton energy spectrum which is not just valid in the endpoint region, but over the entire phase space.Comment: 8 Pages, LaTeX, 2 figures; a few typos corrected and some clarifications added, final journal versio

Open Business Models and Closed-Loop Value Chains: Redefining the Firm-Consumer Relationship

Driven by recent socio-economic developments, manufacturing firms increasingly adapt their business models along two dimensions. Apart from vertically integrating the entire product life cycle, traditionally separated tasks are re-allocated into new forms of horizontal stakeholder collaborations. Incorporating these two dimensions, this article develops a framework of nine business model archetypes that holistically capture the increasing openness of business models towards consumers in the emerging closed-loop value chain. Using illustrative examples, it demonstrates their broad applicability in different industries and derives important managerial implications for firm-consumer relationships, the relevance of consumer communities, new product development activities, and the sustainability of business models

Fingerprints of the Magnetic Polaron in Nonequilibrium Electron Transport through a Quantum Wire Coupled to a Ferromagnetic Spin Chain

We study nonequilibrium quantum transport through a mesoscopic wire coupled via local exchange to a ferromagnetic spin chain. Using the Keldysh formalism in the self-consistent Born approximation, we identify fingerprints of the magnetic polaron state formed by hybridization of electronic and magnon states. Because of its low decoherence rate, we find coherent transport signals. Both elastic and inelastic peaks of the differential conductance are discussed as a function of external magnetic fields, the polarization of the leads and the electronic level spacing of the wire.Comment: 5 pages, 4 figure

Autonomous Calibration of Single Spin Qubit Operations

Fully autonomous precise control of qubits is crucial for quantum information processing, quantum communication, and quantum sensing applications. It requires minimal human intervention on the ability to model, to predict and to anticipate the quantum dynamics [1,2], as well as to precisely control and calibrate single qubit operations. Here, we demonstrate single qubit autonomous calibrations via closed-loop optimisations of electron spin quantum operations in diamond. The operations are examined by quantum state and process tomographic measurements at room temperature, and their performances against systematic errors are iteratively rectified by an optimal pulse engineering algorithm. We achieve an autonomous calibrated fidelity up to 1.00 on a time scale of minutes for a spin population inversion and up to 0.98 on a time scale of hours for a Hadamard gate within the experimental error of 2%. These results manifest a full potential for versatile quantum nanotechnologies.Comment: 9 pages, 5 figure

Clockwise Stellar Disk and the Dark Mass in the Galactic Center

Two disks of young stars have recently been discovered in the Galactic Center. The disks are rotating in the gravitational field of the central black hole at radii r=0.1-0.3 pc and thus open a new opportunity to measure the central mass. We find that the observed motion of stars in the clockwise disk implies M=4.3+/-0.5 million solar masses for the fiducial distance to the Galactic Center R_0=8 kpc and derive the scaling of M with R_0. As a tool for our estimate we use orbital roulette, a recently developed method. The method reconstructs the three-dimensional orbits of the disk stars and checks the randomness of their orbital phases. We also estimate the three-dimensional positions and orbital eccentricities of the clockwise-disk stars.Comment: Comments: 16 pages, 5 figures, ApJ, in pres

Ectoproct and entoproct type material: Reexamination of species from New England and Bermuda named by A. E. Verrill, J. W. Dawson and E. Desor

A. E. Verrill, J. W. Dawson, and E. Desor named 23 species of North American east coast ectoprocts and entoprocts prior to 1902. Chiefly from lack of illustration, the majority of these have been misunderstood in the literature. We have found material leading to a better understanding of 15 of these species in collections of the Peabody Museum of Natural History, Yale University, the U.S. National Museum, and the American Museum of Natural History. The following ectoproct species are described (original names): Amathia goodei Verrill, Bugula cucullata Verrill, Bugula decorata Verrill, Bugula flexilis Verrill, Bugula (Caulibugula) armata Verrill, Bugulella fragilis Verrill, Cellularia turrita Desor, Discopora nitida Verrill, Escharina porosa Verrill, Gemellaria willisii Dawson, Hippoporina verrilli Maturo and Schopf, Hippothoa expansa Dawson, Lepralia americana Verrill, Lepralia plana Dawson, Porellina stellata Verrill. One entoproct, Barentsia timida Verrill, is described. The coefficient of variation was determined for standard dimensional features. Data collected support Cheetham\u27s statistical verification that the most useful dimensional features for taxonomic purposes are ovicell length and width, zooid length, and primary orifice length and width. Length of adventitous avicularia and zooid width are the most variable of the traits measured, particularly in encrusting forms which also have extensive secondary calcification