6,441 research outputs found

    Gamale Kham phonology revisited, with Devanagari-based orthography and lexicon

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    The purpose of this article is twofold. Firstly, it is a revision of certain aspects of the phonological analysis of Gamāle Khām by Wilde (2011), a lesser known Central Himalayish language spoken in midwestern Nepal. Secondly it attempts to reduce Gamāle Khām phonology to writing. The preliminary orthography suggested in this article uses the Devanāgarī script, and is supported by an interlinearised text, and a lexicon comprising approximately 1,400 headwords which have also been transcribed with IPA, and glossed in Nepali and English

    A Monthly Cycle in Food Expenditure and Intake by Participants in the U.S. Food Stamp Program

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    This paper uses nationally representative data to describe monthly cycles in food expenditure and food intake by food stamp recipients. Food expenditure peaks sharply in the first 3 days after food stamps are received. The corresponding cycle in food intake differs for various categories of food stamp recipients. Food stamp recipients who also receive AFDC appear to maintain steady food intake across the whole month, while AFDC nonrecipients experience a significant drop in intake at the end of the month. Children appear to maintain steady food intake, while adults appear to experience a significant drop. Households that conduct major grocery shopping trips more frequently than once per month maintain steady food intake, while households that shop less frequently experience a significant drop. The food stamp cycle has implications for two areas of research: the measurement of hunger and food insecurity in the United States and the measurement of the impact of the U.S. Food Stamp Program. Intramonthly patterns in food expenditure and food intake have potential implications for policy decisions about the frequency of food stamp benefit delivery, the evaluation of new electronic benefit transfer systems that are replacing traditional food stamp coupons, and nutrition education efforts.

    Late Wenlock (middle Silurian) bio-events: Caused by volatile boloid impact/s

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    Late Wenlockian (late mid-Silurian) life is characterized by three significant changes or bioevents: sudden development of massive carbonate reefs after a long interval of limited reef growth; sudden mass mortality among colonial zooplankton, graptolites; and origination of land plants with vascular tissue (Cooksonia). Both marine bioevents are short in duration and occur essentially simultaneously at the end of the Wenlock without any recorded major climatic change from the general global warm climate. These three disparate biologic events may be linked to sudden environmental change that could have resulted from sudden infusion of a massive amount of ammonia into the tropical ocean. Impact of a boloid or swarm of extraterrestrial bodies containing substantial quantities of a volatile (ammonia) component could provide such an infusion. Major carbonate precipitation (formation), as seen in the reefs as well as, to a more limited extent, in certain brachiopods, would be favored by increased pH resulting from addition of a massive quantity of ammonia into the upper ocean. Because of the buffer capacity of the ocean and dilution effects, the pH would have returned soon to equilibrium. Major proliferation of massive reefs ceased at the same time. Addition of ammonia as fertilizer to terrestrial environments in the tropics would have created optimum environmental conditions for development of land plants with vascular, nutrient-conductive tissue. Fertilization of terrestrial environments thus seemingly preceded development of vascular tissue by a short time interval. Although no direct evidence of impact of a volatile boloid may be found, the bioevent evidence is suggestive that such an impact in the oceans could have taken place. Indeed, in the case of an ammonia boloid, evidence, such as that of the Late Wenlockian bioevents may be the only available data for impact of such a boloid

    Unconstrained Capacities of Quantum Key Distribution and Entanglement Distillation for Pure-Loss Bosonic Broadcast Channels

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    We consider quantum key distribution (QKD) and entanglement distribution using a single-sender multiple-receiver pure-loss bosonic broadcast channel. We determine the unconstrained capacity region for the distillation of bipartite entanglement and secret key between the sender and each receiver, whenever they are allowed arbitrary public classical communication. A practical implication of our result is that the capacity region demonstrated drastically improves upon rates achievable using a naive time-sharing strategy, which has been employed in previously demonstrated network QKD systems. We show a simple example of the broadcast QKD protocol overcoming the limit of the point-to-point strategy. Our result is thus an important step toward opening a new framework of network channel-based quantum communication technology.Comment: 9 pages, 5 figure

    R\'enyi generalizations of quantum information measures

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    Quantum information measures such as the entropy and the mutual information find applications in physics, e.g., as correlation measures. Generalizing such measures based on the R\'enyi entropies is expected to enhance their scope in applications. We prescribe R\'enyi generalizations for any quantum information measure which consists of a linear combination of von Neumann entropies with coefficients chosen from the set {-1,0,1}. As examples, we describe R\'enyi generalizations of the conditional quantum mutual information, some quantum multipartite information measures, and the topological entanglement entropy. Among these, we discuss the various properties of the R\'enyi conditional quantum mutual information and sketch some potential applications. We conjecture that the proposed R\'enyi conditional quantum mutual informations are monotone increasing in the R\'enyi parameter, and we have proofs of this conjecture for some special cases.Comment: 9 pages, related to and extends the results from arXiv:1403.610

    Unconstrained distillation capacities of a pure-loss bosonic broadcast channel

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    Bosonic channels are important in practice as they form a simple model for free-space or fiber-optic communication. Here we consider a single-sender two-receiver pure-loss bosonic broadcast channel and determine the unconstrained capacity region for the distillation of bipartite entanglement and secret key between the sender and each receiver, whenever they are allowed arbitrary public classical communication. We show how the state merging protocol leads to achievable rates in this setting, giving an inner bound on the capacity region. We also evaluate an outer bound on the region by using the relative entropy of entanglement and a `reduction by teleportation' technique. The outer bounds match the inner bounds in the infinite-energy limit, thereby establishing the unconstrained capacity region for such channels. Our result could provide a useful benchmark for implementing a broadcasting of entanglement and secret key through such channels. An important open question relevant to practice is to determine the capacity region in both this setting and the single-sender single-receiver case when there is an energy constraint on the transmitter.Comment: v2: 6 pages, 3 figures, introduction revised, appendix added where the result is extended to the 1-to-m pure-loss bosonic broadcast channel. v3: minor revision, typo error correcte

    Bounds on entanglement distillation and secret key agreement for quantum broadcast channels

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    The squashed entanglement of a quantum channel is an additive function of quantum channels, which finds application as an upper bound on the rate at which secret key and entanglement can be generated when using a quantum channel a large number of times in addition to unlimited classical communication. This quantity has led to an upper bound of log((1+η)/(1η))\log((1+\eta)/(1-\eta)) on the capacity of a pure-loss bosonic channel for such a task, where η\eta is the average fraction of photons that make it from the input to the output of the channel. The purpose of the present paper is to extend these results beyond the single-sender single-receiver setting to the more general case of a single sender and multiple receivers (a quantum broadcast channel). We employ multipartite generalizations of the squashed entanglement to constrain the rates at which secret key and entanglement can be generated between any subset of the users of such a channel, along the way developing several new properties of these measures. We apply our results to the case of a pure-loss broadcast channel with one sender and two receivers.Comment: 35 pages, 1 figure, accepted for publication in IEEE Transactions on Information Theor
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