5,000 research outputs found

    Convolutional coded dual header pulse interval modulation for line of sight photonic wireless links.

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    The analysis and simulation for convolutional coded dual header pulse interval modulation (CC-DH-PIM) scheme using a rate ½ convolutional code with the constraint length of 3 is presented. Decoding is implemented using the Viterbi algorithm with a hard decision. Mathematical analysis for the slot error rate (SER) upper bounds is presented and results are compared with the simulated data for a number of different modulation techniques. The authors show that the coded DH-PIM outperforms the pulse position modulation (PPM) scheme and offers >4 dB code gain at the SER of 10?4 compared to the standard DH-PIM. Results presented show that the CC-DH-PIM with a higher constraint length of 7 offers a code gain of 2 dB at SER of 10?5 compared to the CC-DH-PIM with a constraint length of 3. However, in CC-DH-PIM the improvement in the error performance is achieved at the cost of reduced transmission throughput compared to the standard DH-PIM

    MIF: Mood Improving/Inhibiting Factor?

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    Although major depressive disorder imposes a serious public health burden and affects nearly one in six individuals in developed countries over their lifetimes, there is still no consensus on its pathophysiology. Inflammation and cytokines have emerged as a promising new avenue in depression research, and, in particular, macrophage migration inhibitory factor (MIF) has been shown to be significant in depression physiology. In this review we summarize current research on MIF and depression. We highlight the arguments for MIF as a pro- and antidepressant species and discuss the potential implications for therapeutics

    Nigeria The Next Generation Report

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    The Next Generation Task Force was convened to explore Nigeria's future at a time of rapid demographic, social, and economic change. Over the next 20 years, Nigeria will experience huge growth in the number of young adults in its society. If these young people are healthy, well educated, and find productive employment, they could boost the country's economy and reinvigorate it culturally and politically. If not, they could be a force for instability and social unrest. The Task Force report is intended to catalyse a broader debate on Nigeria's future – and especially the needs of its young people. The next generation is beginning to find its voice. If Nigeria can harness its ideas and energy, then its future will surely be bright.Nigeria, demography, growth

    Game based cyber security training: are serious games suitable for cyber security training?

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    Security research and training is attracting a lot of investment and interest from governments and the private sector. Most efforts have focused on physical security, while cyber security or digital security has been given less importance. With recent high-profile attacks it has become clear that training in cyber security is needed. Serious Games have the capability to be effective tools for public engagement and behavioural change and role play games, are already used by security professionals. Thus cyber security seems especially well-suited to Serious Games. This paper investigates whether games can be effective cyber security training tools. The study is conducted by means of a structured literature review supplemented with a general web search. While there are early positive indications there is not yet enough evidence to draw any definite conclusions. There is a clear gap in target audience with almost all products and studies targeting the general public and very little attention given to IT professionals and managers. The products and studies also mostly work over a short period, while it is known that short-term interventions are not particularly effective at affecting behavioural change

    TailX: Scheduling Heterogeneous Multiget Queries to Improve Tail Latencies in Key-Value Stores

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    International audienceUsers of interactive services such as e-commerce platforms have high expectations for the performance and responsiveness of these services. Tail latency, denoting the worst service times, contributes greatly to user dissatisfaction and should be minimized. Maintaining low tail latency for interactive services is challenging because a request is not complete until all its operations are completed. The challenge is to identify bottleneck operations and schedule them on uncoordinated backend servers with minimal overhead, when the duration of these operations are heterogeneous and unpredictable. In this paper, we focus on improving the latency of multiget operations in cloud data stores. We present TailX, a task-aware multiget scheduling algorithm that improves tail latencies under heterogeneous workloads. TailX schedules operations according to an estimation of the size of the corresponding data, and allows itself to procrastinate some operations to give way to higher priority ones. We implement TailX in Cassandra, a widely used key-value store. The result is an improved overall performance of the cloud data stores for a wide variety of heterogeneous workloads. Specifically, our experiments under heterogeneous YCSB workloads show that TailX outperforms state-of-the-art solutions and reduces tail latencies by up to 70% and median latencies by up to 75%

    Swift J164449.3+573451 event: generation in the collapsing star cluster?

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    We discuss the multiband energy release in a model of a collapsing galactic nucleus, and we try to interpret the unique super-long cosmic gamma-ray event Swift J164449.3+573451 (GRB 110328A by early classification) in this scenario. Neutron stars and stellar-mass black holes can form evolutionary a compact self-gravitating subsystem in the galactic center. Collisions and merges of these stellar remnants during an avalanche contraction and collapse of the cluster core can produce powerful events in different bands due to several mechanisms. Collisions of neutron stars and stellar-mass black holes can generate gamma-ray bursts (GRBs) similar to the ordinary models of short GRB origin. The bright peaks during the first two days may also be a consequence of multiple matter supply (due to matter release in the collisions) and accretion onto the forming supermassive black hole. Numerous smaller peaks and later quasi-steady radiation can arise from gravitational lensing, late accretion of gas onto the supermassive black hole, and from particle acceleration by shock waves. Even if this model will not reproduce exactly all the Swift J164449.3+573451 properties in future observations, such collapses of galactic nuclei can be available for detection in other events.Comment: 7 pages, replaced by the final versio

    Neuromedin U receptors in GtoPdb v.2023.1

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    Neuromedin U receptors (provisional nomenclature as recommended by NC-IUPHAR [30]) are activated by the endogenous 25 amino acid peptide neuromedin U (neuromedin U-25, NmU-25), a peptide originally isolated from pig spinal cord [92]. In humans, NmU-25 appears to be the sole product of a precursor gene (NMU, P48645) showing a broad tissue distribution, but which is expressed at highest levels in the upper gastrointestinal tract, CNS, bone marrow and fetal liver. Much shorter versions of NmU are found in some species, but not in human, and are derived at least in some instances from the proteolytic cleavage of the longer NmU. Despite species differences in NmU structure, the C-terminal region (particularly the C-terminal pentapeptide) is highly conserved and contains biological activity. Neuromedin S (neuromedin S-33) has also been identified as an endogenous agonist [97]. NmS-33 is, as its name suggests, a 33 amino-acid product of a precursor protein derived from a single gene and contains an amidated C-terminal heptapeptide identical to NmU. NmS-33 appears to activate NMU receptors with equivalent potency to NmU-25

    Neuromedin U receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

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    Neuromedin U receptors (provisional nomenclature as recommended by NC-IUPHAR [29]) are activated by the endogenous 25 amino acid peptide neuromedin U (neuromedin U-25, NmU-25), a peptide originally isolated from pig spinal cord [90]. In humans, NmU-25 appears to be the sole product of a precursor gene (NMU, P48645) showing a broad tissue distribution, but which is expressed at highest levels in the upper gastrointestinal tract, CNS, bone marrow and fetal liver. Much shorter versions of NmU are found in some species, but not in human, and are derived at least in some instances from the proteolytic cleavage of the longer NmU. Despite species differences in NmU structure, the C-terminal region (particularly the C-terminal pentapeptide) is highly conserved and contains biological activity. Neuromedin S (neuromedin S-33) has also been identified as an endogenous agonist [95]. NmS-33 is, as its name suggests, a 33 amino-acid product of a precursor protein derived from a single gene and contains an amidated C-terminal heptapeptide identical to NmU. NmS-33 appears to activate NMU receptors with equivalent potency to NmU-25

    Modelling diverse root density dynamics and deep nitrogen uptake — a simple approach

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    We present a 2-D model for simulation of root density and plant nitrogen (N) uptake for crops grown in agricultural systems, based on a modification of the root density equation originally proposed by Gerwitz and Page in J Appl Ecol 11:773–781, (1974). A root system form parameter was introduced to describe the distribution of root length vertically and horizontally in the soil profile. The form parameter can vary from 0 where root density is evenly distributed through the soil profile, to 8 where practically all roots are found near the surface. The root model has other components describing root features, such as specific root length and plant N uptake kinetics. The same approach is used to distribute root length horizontally, allowing simulation of root growth and plant N uptake in row crops. The rooting depth penetration rate and depth distribution of root density were found to be the most important parameters controlling crop N uptake from deeper soil layers. The validity of the root distribution model was tested with field data for white cabbage, red beet, and leek. The model was able to simulate very different root distributions, but it was not able to simulate increasing root density with depth as seen in the experimental results for white cabbage. The model was able to simulate N depletion in different soil layers in two field studies. One included vegetable crops with very different rooting depths and the other compared effects of spring wheat and winter wheat. In both experiments variation in spring soil N availability and depth distribution was varied by the use of cover crops. This shows the model sensitivity to the form parameter value and the ability of the model to reproduce N depletion in soil layers. This work shows that the relatively simple root model developed, driven by degree days and simulated crop growth, can be used to simulate crop soil N uptake and depletion appropriately in low N input crop production systems, with a requirement of few measured parameters

    The Visual Construction of the Umayyad Caliphate in Al-Andalus through the Great Mosque of Cordoba

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    My first exposure to the epigraphic program of the Great Mosque of Cordoba, published in 2001, came from reading an article on the ideological meaning of the decoration and the Quranic citations inscribed in al-H. akam II’s addition to the building. In that article, I concluded that the Quranic verses found in the mosque were chosen not only for being a universal proclamation of divine power and praise for the Umayyad dynasty, as proposed by Nuha Khoury in 1996, but also because they clearly fitted in with the particular Andalusi, or rather Cordoban, religious, cultural, and political context in the first half of the 10th century. Most of the inscriptions had been read in the 19th century by Amador de los Ríos, but some of them remained uninterpreted. Given that they were an essential part of the ideological message, it seemed appropriate to revisit the critical reading of the epigraphic program and determine its full meaning. Later, I discussed other architectural aspects of the Great Mosque in which the links to the Andalusi and the eastern Umayyad traditions are a key aspect in understanding why these forms were chosen. Damascus, the eastern Umayyad capital, and to a lesser extent Medina and the Abbasid capitals, became the model for the caliphs of Cordoba. This article proposes to revisit the main architectural and decorative features of the caliphal enlargements of the Great Mosque of Cordoba in order to reflect on the meaning and forms of its epigraphic program
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