670 research outputs found

    The effect of Hamming distances on permutation codes for multiuser communication in the power line communications channel

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    We partition permutation sequences into groups to form permutation codes for multiuser communication. Each group becomes a codebook for each user in a multiuser communication system. We present simulation results for the performance of different partitions of permutation codes for multiuser communication, where the codes are to be used in channels with background noise and jamming, such as the Power Line Communications (PLC) channel. With the help of the simulation results, we show that by partitioning codebooks according to distance properties we can affect the performance of the codes. The permutation codes have codewords of length M with symbols taken from an alphabet whose cardinality is M, where M is any integer. Each symbol may be seen as representing one out of the M frequencies in an M-ary Frequency Shift keying modulation scheme, for example. Each user has a codebook of cardinality greater or equal to M and there can be a maximum of M - 1 users communicating at the same time through a multiple access OR channel

    Consensus and contention in the priority setting process: examining the health sector in Uganda.

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    Health priority setting is a critical and contentious issue in low-income countries because of the high burden of disease relative to the limited resource envelope. Many sophisticated quantitative tools and policy frameworks have been developed to promote transparent priority setting processes and allocative efficiency. However, low-income countries frequently lack effective governance systems or implementation capacity, so high-level priorities are not determined through evidence-based decision-making processes. This study uses qualitative research methods to explore how key actors' priorities differ in low-income countries, using Uganda as a case study. Human resources for health, disease prevention and family planning emerge as the common priorities among actors in the health sector (although the last of these is particularly emphasized by international agencies) because of their contribution to the long-term sustainability of health-care provision. Financing health-care services is the most disputed issue. Participants from the Ugandan Ministry of Health preferentially sought to increase net health expenditure and government ownership of the health sector, while non-state actors prioritized improving the efficiency of resource use. Ultimately it is apparent that the power to influence national health outcomes lies with only a handful of decision-makers within key institutions in the health sector, such as the Ministries of Health, the largest bilateral donors and the multilateral development agencies. These power relations reinforce the need for ongoing research into the paradigms and strategic interests of these actors

    A disease-associated gene desert directs macrophage inflammation through ETS2

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    Increasing rates of autoimmune and inflammatory disease present a burgeoning threat to human health1. This is compounded by the limited efficacy of available treatments1 and high failure rates during drug development2, highlighting an urgent need to better understand disease mechanisms. Here we show how functional genomics could address this challenge. By investigating an intergenic haplotype on chr21q22—which has been independently linked to inflammatory bowel disease, ankylosing spondylitis, primary sclerosing cholangitis and Takayasu’s arteritis3–6—we identify that the causal gene, ETS2, is a central regulator of human inflammatory macrophages and delineate the shared disease mechanism that amplifies ETS2 expression. Genes regulated by ETS2 were prominently expressed in diseased tissues and more enriched for inflammatory bowel disease GWAS hits than most previously described pathways. Overexpressing ETS2 in resting macrophages reproduced the inflammatory state observed in chr21q22-associated diseases, with upregulation of multiple drug targets, including TNF and IL-23. Using a database of cellular signatures7, we identified drugs that might modulate this pathway and validated the potent anti-inflammatory activity of one class of small molecules in vitro and ex vivo. Together, this illustrates the power of functional genomics, applied directly in primary human cells, to identify immune-mediated disease mechanisms and potential therapeutic opportunities

    Transient field g factor and mean-life measurements with a rare isotope beam of 126Sn

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    Background: The g factors and lifetimes of the 21+ states in the stable, proton-rich Sn isotopes have been measured, but there is scant information on neutron-rich Sn isotopes. Purpose: Measurement of the g factor and the lifetime of the 21+ state at 1.141 MeV in neutron-rich 126Sn (T1/2=2. 3×105y). Method: Coulomb excitation in inverse kinematics together with the transient field and the Doppler shift attenuation techniques were applied to a radioactive beam of 126Sn at the Holifield Radioactive Ion Beam Facility. Results: g(21+)=-0.25(21) and τ(21+)=1.5(2) ps were obtained. Conclusions: The data are compared to large-scale shell-model and quasiparticle random-phase calculations. Neutrons in the h11/2 and d3/2 orbitals play an important role in the structure of the 21+ state of 126Sn. Challenges, limitations, and implications for such experiments at future rare isotope beam facilities are discussed
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