Uplink Multiuser MIMO Detection Scheme with Reduced Computational Complexity

The wireless communication systems with multiple antennas have recently received significant attention due to their higher capacity and better immunity to fading channels as compared to single antenna systems. A fast antenna selection scheme has been introduced for the uplink multiuser multiple-input multiple-output (MIMO) detection to achieve diversity gains, but the computational complexity of the fast antenna selection scheme in multiuser systems is very high due to repetitive pseudo-inversion computations. In this paper, a new uplink multiuser detection scheme is proposed adopting a switch-and-examine combining (SEC) scheme and the Cholesky decomposition to solve the computational complexity problem. K users are considered that each users is equipped with two transmit antennas for Alamouti space-time block code (STBC) over wireless Rayleigh fading channels. Simulation results show that the computational complexity of the proposed scheme is much lower than the systems with exhaustive and fast antenna selection, while the proposed scheme does not experience the degradations of bit error rate (BER) performances

Tensor-to-Scalar Ratio in Eddington-inspired Born-Infeld Inflation

We investigate the scalar perturbation of the inflation model driven by a massive-scalar field in Eddington-inspired Born-Infeld gravity. We focus on the perturbation at the attractor stage in which the first and the second slow-roll conditions are satisfied. The scalar perturbation exhibits the corrections to the chaotic inflation model in general relativity. We find that the tensor-to-scalar ratio becomes smaller than that of the usual chaotic inflation.Comment: 9 pages. revised version to appear in EPJC, with minor typo corrections. arXiv admin note: text overlap with arXiv:1404.608

Light bottom squark and gluino confront electroweak precision measurements

We address the compatibility of a light sbottom (mass 2\sim 5.5 \gev) and a light gluino (mass 12\sim 16 \gev) with electroweak precision measurements. Such light particles have been suggested to explain the observed excess in the $b$ quark production cross section at the Tevatron. The electroweak observables may be affected by the sbottom and gluino through the SUSY-QCD corrections to the $Zbb$ vertex. We examine, in addition to the SUSY-QCD corrections, the electroweak corrections to the gauge boson propagators from the stop which are allowed to be light from the SU(2)$_L$ symmetry. We find that this scenario is strongly disfavored from electroweak precision measurements unless the heavier sbottom mass eigenstate is lighter than 180\gev and the left-right mixing in the stop sector is sufficiently large. This implies that one of the stops should be lighter than about 98\gev.Comment: 4 pages, revtex, 2 figures. Reference added, version to appear in Phys.Rev.Let

The vertical structure of Jupiter's equatorial zonal wind above the cloud deck, derived using mesoscale gravity waves

Data from the Galileo Probe, collected during its descent into Jupiter's atmosphere, is used to obtain a vertical profile of the zonal wind from $\mathbf{\sim 0.5}$ bar (upper troposphere) to $\mathbf{\sim 0.1\, \mu{bar}}$ (lower thermosphere) at the probe entry site. This is accomplished by constructing a map of gravity wave Lomb-Scargle periodograms as a function of altitude. The profile obtained from the map indicates that the wind speed above the visible cloud deck increases with height to $\mathbf{\sim 150}$ m\,s$\mathbf{^{-1}}$ and then levels off at this value over a broad altitude range. The location of the turbopause, as a region of wide wave spectrum, is also identified from the map. In addition, a cross-equatorial oscillation of a jet, which has previously been linked to the quasi-quadrennial oscillation in the stratosphere, is suggested by the profile.Comment: 5 pages, 4 figures. Accepted for publication in GR

Quarkonium production and NRQCD matrix elements

Most recent calculations of quarkonium production are based on the NRQCD factorization formalism. This formalism is reviewed. To make predictions about specific cross section, universal NRQCD matrix elements need to be extracted from experiments. Extractions from different experimental situations are compared, with some emphasis on the extraction from LEP.Comment: 6 pages, 1 figure, talk given at 4th International Conference on Hyperons, Charm and Beauty Hadrons, Valencia, Spain, 27-30 Jun 200

Can Rural Communities Comply with the New Arsenic Standard for Drinking Water?

Our primary concern in this paper is to determine to what extent small communities have difficulty meeting the new stricter 2001 standard for arsenic levels in their drinking water. To do this we survey water users in rural Minnesota communities that had arsenic levels in their water supply exceeding 10 g/L during 2001-2006. Our survey results show that after obtaining complete information concerning the arsenic levels in their drinking water consumers with relatively low levels of arsenic were willing to pay $8-9 annually, while those with high levels of arsenic are willing to pay$15-17 annually. We also found that consumer’s willingness to pay (WTP) didn’t vary by community size. Thus, we conclude that compared to compliance costs ($58-327 per capita annually) small rural communities were likely to find it difficult to cover the cost of compliance through increased water charges. Since many of the communities have to cover these costs of compliance by raising water charges, we ask the basic question: are there better treatment options for these rural communities that will lower the cost to consumers? One option might be to encourage individual householders to use household water treatment devices for communities serving fewer than 500 people. The devices could be made available by the local entity supplying the community’s water possibly at a subsidized rate along with complete information about the arsenic level in the water supply.Community/Rural/Urban Development, Resource /Energy Economics and Policy,

Learning to Translate in Real-time with Neural Machine Translation

Translating in real-time, a.k.a. simultaneous translation, outputs translation words before the input sentence ends, which is a challenging problem for conventional machine translation methods. We propose a neural machine translation (NMT) framework for simultaneous translation in which an agent learns to make decisions on when to translate from the interaction with a pre-trained NMT environment. To trade off quality and delay, we extensively explore various targets for delay and design a method for beam-search applicable in the simultaneous MT setting. Experiments against state-of-the-art baselines on two language pairs demonstrate the efficacy of the proposed framework both quantitatively and qualitatively.Comment: 10 pages, camera read