1,766 research outputs found

    A Mean-field Approach for an Intercarrier Interference Canceller for OFDM

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    The similarity of the mathematical description of random-field spin systems to orthogonal frequency-division multiplexing (OFDM) scheme for wireless communication is exploited in an intercarrier-interference (ICI) canceller used in the demodulation of OFDM. The translational symmetry in the Fourier domain generically concentrates the major contribution of ICI from each subcarrier in the subcarrier's neighborhood. This observation in conjunction with mean field approach leads to a development of an ICI canceller whose necessary cost of computation scales linearly with respect to the number of subcarriers. It is also shown that the dynamics of the mean-field canceller are well captured by a discrete map of a single macroscopic variable, without taking the spatial and time correlations of estimated variables into account.Comment: 7pages, 3figure

    Marking a new holy community: God’s neighbors and the ascendancy of a new religious hegemony in Israel

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    Meni Ya'ish's 2012 film God's Neighbors marks a significant cultural moment in the legitimation of Jewish religiosity in Israel and records an important moment in the country's metamorphosis in recent years, marking a change from a secular, liberal society to a more fundamentalist religious one. The film demonstrates this change in three interrelated ways. First, by combining Jewish religiosity with a powerful and aggressive Israeli Mizrahi masculine identity, the film re-legitimizes Jewish religiosity, presents it as attractive and sexy, and declares it as the new Israeli hegemony. Second, by abstaining from killing members of a rival Arab gang, the film symbolically minimizes the conflict between Jews and Arabs and advances the importance of mythical Jewish time over Zionist historical time. Finally, by ending happily with a union between Avi and his girl Miri, the film provides a neat closure that offers an alluringly simple hasidic-like tale to Jewish life in Israel today. As such, the film marks the decline of Israeli Statism and the rise of alternative redemptive narratives in Israel that are primarily religious

    Physiological-genetic dissection of drought resistance in wild emmer wheat

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    Beeping a Maximal Independent Set

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    We consider the problem of computing a maximal independent set (MIS) in an extremely harsh broadcast model that relies only on carrier sensing. The model consists of an anonymous broadcast network in which nodes have no knowledge about the topology of the network or even an upper bound on its size. Furthermore, it is assumed that an adversary chooses at which time slot each node wakes up. At each time slot a node can either beep, that is, emit a signal, or be silent. At a particular time slot, beeping nodes receive no feedback, while silent nodes can only differentiate between none of its neighbors beeping, or at least one of its neighbors beeping. We start by proving a lower bound that shows that in this model, it is not possible to locally converge to an MIS in sub-polynomial time. We then study four different relaxations of the model which allow us to circumvent the lower bound and find an MIS in polylogarithmic time. First, we show that if a polynomial upper bound on the network size is known, it is possible to find an MIS in O(log^3 n) time. Second, if we assume sleeping nodes are awoken by neighboring beeps, then we can also find an MIS in O(log^3 n) time. Third, if in addition to this wakeup assumption we allow sender-side collision detection, that is, beeping nodes can distinguish whether at least one neighboring node is beeping concurrently or not, we can find an MIS in O(log^2 n) time. Finally, if instead we endow nodes with synchronous clocks, it is also possible to find an MIS in O(log^2 n) time.Comment: arXiv admin note: substantial text overlap with arXiv:1108.192

    A two-dimensional representation of four-dimensional gravitational waves

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    The Einstein equation in D dimensions, if restricted to the class of space-times possessing n = D - 2 commuting hypersurface-orthogonal Killing vectors, can be equivalently written as metric-dilaton gravity in 2 dimensions with n scalar fields. For n = 2, this results reduces to the known reduction of certain 4-dimensional metrics which include gravitational waves. Here, we give such a representation which leads to a new proof of the Birkhoff theorem for plane-symmetric space--times, and which leads to an explanation, in which sense two (spin zero-) scalar fields in 2 dimensions may incorporate the (spin two-) gravitational waves in 4 dimensions. (This result should not be mixed up with well--known analogous statements where, however, the 4-dimensional space-time is supposed to be spherically symmetric, and then, of course, the equivalent 2-dimensional picture cannot mimic any gravitational waves.) Finally, remarks on hidden symmetries in 2 dimensions are made.Comment: 12 pages, LaTeX, no figures, Int. J. Mod. Phys. D in prin
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