1,750 research outputs found

    Superstring Relics, Supersymmetric Fragmentation and UHECR

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    Superstring theory predicts the existence of relic metastable particles whose average lifetime is longer than the age of the universe and which could, in principle, be good dark matter candidates. At the same time, these states would be responsible for the Ultra High Energy Cosmic Rays (UHECR) events which will be searched for by various experimental collaborations in the near future. We describe a possible phenomenological path which could be followed in order to search for new physics in their detection.Comment: 7 pages 4 Figs. Plenary Talk presented by Claudio Coriano' at the 1st Intl. Conf. on String Phenomenology, Oxford, UK, July 6-11, 200

    Nuclear re-interaction effects in quasi-elastic neutrino nucleus scattering

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    The quasi-elastic neutrino-nucleus cross section has been calculated by using a Fermi gas model corrected to consider the re-scattering between the emitted nucleon and the rest nucleus. As an example of the relevance of this effect we show results for the muon production cross section on 16O target.Comment: 7 pages, 4 Postscript figures, Contribution to NuInt01 Workshop, KEK, Tsukuba, Japa

    Identification of Showers with Cores Outside the ARGO-YBJ Detector

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    In any EAS array, the rejection of events with shower cores outside the detector boundaries is of great importance. A large difference between the true and the reconstructed shower core positions may lead to a systematic miscalculation of some shower characteristics. Moreover, an accurate determination of the shower core position for selected internal events is important to reconstruct the primary direction using conical fits to the shower front, improving the detector angular resolution, or to performe an efficient gamma/hadron discrimination. In this paper we present a procedure able to identify and reject showers with cores outside the ARGO-YBJ carpet boundaries. A comparison of the results for gamma and proton induced showers is reported.Comment: 4 pages, to be published in the Proceedings of the 28th International Cosmic Ray Conference (Tsukuba, Japan 2003

    Expected sensitivity of ARGO-YBJ to detect point gamma-ray sources

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    ARGO-YBJ is a full coverage air shower detector currently under construction at the Yangbajing Laboratory (4300 m a.s.l., Tibet, China). First data obtained with a subset of the apparatus will be available in summer 2003 while the full detector operation is expected in 2005. One of the main aims of ARGO-YBJ is the observation of gamma-ray sources, at an energy threshold of a few hundreds GeV. In this paper we present the expected sensitivity to detect point gamma ray sources, with particular attention to the Crab Nebula. According to our simulations a Crab-like signal could be detected in one year of operation with a statistical significance of 10 standard deviations, without any gamma/hadron discrimination.Comment: 4 pages, 2 Postscript figure

    Lagrangian matheuristics for the Quadratic Multiple Knapsack Problem

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    The Quadratic Multiple Knapsack Problem (QMKP) is a challenging combinatorial optimization problem combining the well-known Quadratic Knapsack Problem with the Multiple Knapsack Problem. After a long stream of research devoted to metaheuristic approaches for large-scale instances, only recently some authors started to study the mathematical properties of the QMKP and proposed exact solution methods for benchmark instances of smaller size. In this paper, we propose the first matheuristic approach for solving the QMKP approximately. The proposed method exploits the strength of a Lagrangian relaxation for the natural quadratic formulation of the QMKP to derive heuristic solutions. Postoptimization local search procedures are embedded in the final framework. Experimental studies show that the resulting deterministic matheuristic approach consistently delivers solutions of very good quality in short computing times

    Next-Generation Sequencing for Clinical Management of Multiple Myeloma : Ready for Prime Time?

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    Personalized treatment is an attractive strategy that promises increased efficacy with reduced side effects in cancer. The feasibility of such an approach has been greatly boosted by next-generation sequencing (NGS) techniques, which can return detailed information on the genome and on the transcriptome of each patient's tumor, thus highlighting biomarkers of response or druggable targets that may differ from case to case. However, while the number of cancers sequenced is growing exponentially, much fewer cases are amenable to a molecularly-guided treatment outside of clinical trials to date. In multiple myeloma, genomic analysis shows a variety of gene mutations, aneuploidies, segmental copy-number changes, translocations that are extremely heterogeneous, and more numerous than other hematological malignancies. Currently, in routine clinical practice we employ reduced FISH panels that only capture three high-risk features as part of the R-ISS. On the contrary, recent advances have suggested that extending genomic analysis to the full spectrum of recurrent mutations and structural abnormalities in multiple myeloma may have biological and clinical implications. Furthermore, increased efficacy of novel treatments can now produce deeper responses, and standard methods do not have enough sensitivity to stratify patients in complete biochemical remission. Consequently, NGS techniques have been developed to monitor the size of the clone to a sensitivity of up to a cell in a million after treatment. However, even these techniques are not within reach of standard laboratories. In this review we will recapitulate recent advances in multiple myeloma genomics, with special focus on the ones that may have immediate translational impact. We will analyze the benefits and pitfalls of NGS-based diagnostics, highlighting crucial aspects that will need to be taken into account before this can be implemented in most laboratories. We will make the point that a new era in myeloma diagnostics and minimal residual disease monitoring is close and conventional genetic testing will not be able to return the required information. This will mandate that even in routine practice NGS should soon be adopted owing to a higher informative potential with increasing clinical benefits

    Early agriculture at the crossroads of China and Southeast Asia: Archaeobotanical evidence and radiocarbon dates from Baiyangcun, Yunnan

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    We report archaeobotanical results from systematic flotation at what is presently the earliest Neolithic site with hard evidence for crop cultivation in the Southwestern Chinese province of Yunnan, at the site of Baiyangcun. Direct AMS dates on rice and millet seeds, included together in a Bayesian model, suggests that sedentary agricultural occupation began ca. 2650 BCE, with cultivation of already domesticated rice (Oryza sativa), broomcorn millet (Panicum miliaceum), and foxtail millet (Setaria italica). Soybean (Glycine cf. max) was also present and presumably cultivated, although it still resembles its wild progenitor in terms of seed size. Additional possible cultivars include melon (Cucumis melo) and an unknown Vigna pulse, while wild gathered resources include fruits and nuts, including hawthorn (Crateagus) and aquatic foxnut (Euryale ferox). Weed flora suggests at least some rice was cultivated in wet (flooded or irrigated fields), while dryland weeds may derive from millet fields. This subsistence system persisted throughout the site's occupation, up to ca. 2050 BCE. These data provide secure evidence for the spread of Chinese Neolithic crops to Yunnan, and provide new evidence for reconstructing possible sources of cereal agriculture in mainland Southeast Asia
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