2,744 research outputs found

    A Strategic Market Game with Seigniorage Costs of Fiat Money

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    A model that includes the cost of producing money is presented and the nature of the inefficient equilibria in the model are examined. It is suggested that if one acknowledges that transactions are a form of production, which requires the consumption resources, then the concept of Pareto optimality is inappropriate for assessing efficiency. Instead it becomes necessary to provide an appropriate comparative analysis of alternative transactions mechanisms in the appropriate context.Strategic market games, Seigniorage costs, Inefficiency

    Detecting heavy charged Higgs bosons at the LHC with triple b-tagging

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    We investigate the charged Higgs boson signal at the LHC using its dominant production and decay modes with triple b-tagging, i.e. tHttˉbbbˉbW+WtH^- \to t\bar tb \to b\bar bb W^+ W^-, followed by leptonic decay of one W and hadronic decay of the other. We consider the continuum background from the associated production of ttˉt\bar t with a b- or a light quark or gluon jet, which can be mis-tagged as b-jet. We reconstruct the top quark masses to identify the 3rd b-jet accompanying the ttˉt\bar t pair, and use its p_T distribution to distinguish the signal from the background. Combining this with the reconstruction of the H±H^\pm mass gives a viable signature over two interesting regions of the parameter space - i.e. tanβ1\tan\beta \sim 1 and mt/mb\sim m_t/m_b.Comment: 10 pages, latex, 4 figure

    Space-Frequency Equalization for Broadband Single Carrier MIMO Systems

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    In this paper, a frequency domain (FD) receiver architecture implemented using estimated channel parameters is derived for broadband single carrier modulations. Co-channel and inter-symbol interferences are compensated by a minimum mean squared error based integrated space-frequency-equalizer (SFE) using the estimated parameters. The integrated SFE in the FD consists of coupled FIR structures, that are jointly optimized by maximizing the desired signal to interference plus noise ratio. We develop analytical expressions and present simulation results for the integrated SFE. Simulation results demonstrate that excellent receiver performance is achieved even for channels with large ISI spans. The proposed SC-SFE outperforms previous layered space frequency (LSF) receivers with imperfect channel knowledge. Further, the parallel receiver architecture yields equal diversity gains to all data streams without the error propagation that is common to most LSF schemes

    Cooperative Relaying with CPFSK and Distributed Space-Time Trellis Codes

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    Cooperative relaying allows single antenna users to achieve diversity and coding gains by utilizing nearby users' transmitting capabilities. We consider a relay system employing constant envelope continuous phase frequency shift keying. Distributed space-time trellis codes are implemented with a novel multiple relay protocol

    Two-user Cooperative Transmission Using Superposition Modulation and Soft Information Combining

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    We propose a cooperative transmission scheme for two users with one common relay using superposition modulation. It uses distributed Turbo codes (DTCs) for each user. The relay always decodes, then interleaves and re-encodes the decoded data. A new packet is formed by combining the re-encoded packets from both users using superposition modulation. This packet is forwarded to the destination with the average receive SNRs of each user. The destination uses the cooperative Turbo decoder of [1] to improve performance. Simulation results show the proposed scheme outperforms XOR based schemes and is simple to implement

    Cooperative Relaying with CPFSK and Distributed Space-Time Trellis Codes

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    Cooperative relaying allows single antenna users to achieve diversity and coding gains by utilizing nearby users' transmitting capabilities. We consider a relay system employing constant envelope continuous phase frequency shift keying. Distributed space-time trellis codes are implemented with a novel multiple relay protocol

    Absence of the cbb3 terminal oxidase reveals an active oxygen-dependent cyclase involved in bacteriochlorophyll biosynthesis in Rhodobacter sphaeroides.

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    The characteristic green color associated with chlorophyll pigments results from the formation of an isocyclic fifth ring on the tetrapyrrole macrocyle during the biosynthesis of these important molecules. This reaction is catalyzed by two unrelated cyclase enzymes employing different chemistries. Oxygenic phototrophs such as plants and cyanobacteria utilize an oxygen-dependent enzyme, the major component of which is a diiron protein named AcsF, while BchE, an oxygen-sensitive [4Fe-4S] cluster protein, dominates in phototrophs inhabiting anoxic environments, such as the purple phototrophic bacterium Rhodobacter sphaeroides We identify a potential acsF in this organism and assay for activity of the encoded protein in a strain lacking bchE under various aeration regimes. Initially, cells lacking bchE did not demonstrate AcsF activity under any condition tested. However, on removal of a gene encoding a subunit of the cbb3-type respiratory terminal oxidase, cells cultured under regimes ranging from oxic to microoxic exhibited cyclase activity, confirming the activity of the oxygen-dependent enzyme in this model organism. Potential reasons for the utilization of an oxygen-dependent enzyme in anoxygenic phototrophs are discussed. IMPORTANCE: The formation of the E ring of (bacterio)chlorophyll pigments is the least well-characterized step in their biosynthesis, remaining enigmatic for over 60 years. Two unrelated enzymes catalyze this cyclization step; O2-dependent and O2-independent forms dominate in oxygenic and anoxygenic phototrophs, respectively. We uncover the activity of an O2-dependent enzyme in the anoxygenic purple phototrophic bacterium Rhodobacter sphaeroides, initially by inactivation of the high affinity terminal respiratory oxidase, cytochrome cbb3 We propose that the O2-dependent form allows for the biosynthesis of a low level of bacteriochlorophyll under oxic conditions, so that a rapid initiation of photosynthetic processes is possible for this bacterium upon a reduction of oxygen tension

    Improved Information Outage Rate in Certain MIMO Systems

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    We propose a simple class of encoding/decoding techniques which can be used to improve the information outage rate of certain multiple-input multiple-output (MIMO) systems. Gains in outage rate can be achieved at low to moderate signal to noise ratios in MIMO systems which have fewer receive antennas than transmit antennas. This performance improvement is due to extra ``virtual'' receive antennas which are created with low complexity signal processing. A simple space-time block code system using virtual receive antennas is also investigated

    Theory of Magnetic Field Induced Spin Density Wave in High Temperature Superconductors

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    The induction of spin density wave (SDW) and charge density wave (CDW) orderings in the mixed state of high TcT_c superconductors (HTS) is investigated by using the self-consistent Bogoliubov-de Gennes equations based upon an effective model Hamiltonian with competing SDW and d-wave superconductivity interactions. For optimized doping sample, the modulation of the induced SDW and its associated CDW is determined by the vortex lattice and their patterns obey the four-fold symmetry. By deceasing doping level, both SDW and CDW show quasi-one dimensional like behavior, and the CDW has a period just half that of the SDW along one direction. From the calculation of the local density of states (LDOS), we found that the majority of the quasi-particles inside the vortex core are localized. All these results are consistent with several recent experiments on HTS

    Fermionic massive modes along cosmic strings

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    The influence on cosmic string dynamics of fermionic massive bound states propagating in the vortex, and getting their mass only from coupling to the string forming Higgs field, is studied. Such massive fermionic currents are numerically found to exist for a wide range of model parameters and seen to modify drastically the usual string dynamics coming from the zero mode currents alone. In particular, by means of a quantization procedure, a new equation of state describing cosmic strings with any kind of fermionic current, massive or massless, is derived and found to involve, at least, one state parameter per trapped fermion species. This equation of state exhibits transitions from subsonic to supersonic regimes while the massive modes are filled.Comment: 27 pages, 15 figures, uses ReVTeX. Shortened version, accepted for publication in Phys. Rev.
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