6,318 research outputs found

    Tardos fingerprinting is better than we thought

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    We review the fingerprinting scheme by Tardos and show that it has a much better performance than suggested by the proofs in Tardos' original paper. In particular, the length of the codewords can be significantly reduced. First we generalize the proofs of the false positive and false negative error probabilities with the following modifications: (1) we replace Tardos' hard-coded numbers by variables and (2) we allow for independently chosen false positive and false negative error rates. It turns out that all the collusion-resistance properties can still be proven when the code length is reduced by a factor of more than 2. Second, we study the statistical properties of the fingerprinting scheme, in particular the average and variance of the accusations. We identify which colluder strategy forces the content owner to employ the longest code. Using a gaussian approximation for the probability density functions of the accusations, we show that the required false negative and false positive error rate can be achieved with codes that are a factor 2 shorter than required for rigid proofs. Combining the results of these two approaches, we show that the Tardos scheme can be used with a code length approximately 5 times shorter than in the original construction.Comment: Modified presentation of result

    Determination of the accumulator plants in Kucukcekmece Lake (Istanbul)

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    Soils are polluted by actions like using commercial fertilizers, pesticides, soil regulators and hormones to increase the amount and quality of agricultural production, discharge of soil and liquid wastes, performing wastewater sludge applications, using polluted waters in agricultural irrigation, atmospheric precipitations and radioactive sprays. It is an important environmental problem to reform and clean the soils polluted with heavy metals. Phytoremediation is a measure which uses several plants to remove the pollutants from water and soil to reduce, completely extract, control or immobilize them. The plants used for this reason are referred to as the accumulators. Metal accumulation can occur in several different families like small annual grass to perennial bushes and trees. For remediation or cleaning of the soils polluted with heavy metals, the ideal plant species are the ones which can produce high amounts of biomass, and can accumulate and tolerate the pollutants. In this study, the Cd and Zn contents obtained from Kucukcekmece Lake border were monitored on monthly basis and it was aimed at determining the plant species with accumulation ability. The plants chosen for this activity were Labiatae galatica, Compositae cardueae, Cypereace carex, and Phragmites australis. Compositae cardueae was the most efficient species in terms of mean heavy metal intake performance.Key words: Heavy metals, accumulators, phytoremediation, soil pollution, Cd, Zn

    Near-field Hybrid Beamforming for Terahertz-band Integrated Sensing and Communications

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    Terahertz (THz) band communications and integrated sensing and communications (ISAC) are two main facets of the sixth generation wireless networks. In order to compensate the severe attenuation, the THz wireless systems employ large arrays, wherein the near-field beam-squint severely degrades the beamforming accuracy. Contrary to prior works that examine only either narrowband ISAC beamforming or far-field models, we introduce an alternating optimization technique for hybrid beamforming design in near-field THz-ISAC scenario. We also propose an efficient approach to compensate near-field beam-squint via baseband beamformers. Via numerical simulations, we show that the proposed approach achieves satisfactory spectral efficiency performance while accurately estimating the near-field beamformers and mitigating the beam-squint without additional hardware components.Comment: Accepted Paper in 2023 IEEE Global Communications Conference (GLOBECOM), Kuala Lumpur, Malaysia, 202

    Regression based polynomial chaos expansion for crop phenology estimation coupled with polsar imagery

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    Crop phenology monitoring using Synthetic Aperture Radar(SAR) data is gaining popularity within the remote sensing community due to SAR’s all weather and large coverage imaging capability. This paper introduces a polynomial chaos expansion (PCE) based regression algorithm to retrieve BBCH scale of crops, which identifies the phenology of crops in a standardized system. The impact and applicability of the proposed methodology is successfully illustrated using the TerraSAR-X dual-pol imagery that was acquired over the cultivation period of paddy-rice fields located in Turkey. To assess the applicability of the methodology, root mean square and correlation analysis were performed under different amount of training data and number of inputs

    Recent graft materials in experimental study stage used in the treatment of nasal septum perforation: a review

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    Various conservative approaches are being used for the treatment of nasal septum perforations (NSPs); however, for permanent results, it is essential to use surgical methods. For this purpose, many various surgical methods have been tried, but a satisfactory method has not yet been determined. In order to eliminate the commonly encountered failure of surgical methods, new graft materials combined with flaps have been tried recently and successful results have been reported.In this review, we examined the scientific literature using Medline, PubMed, and Google by using the keywords "nasal septum perforation", "animal study", and "graft". According to the results obtained, we compiled graft materials that have been used in experimental stage related to this subject and reported to have achieved successful results, especially when combined with flaps. These materials seem promising for the successful closure of the hard-to-treat NSPs

    Sedation and Analgesia in Intensive Care: A Comparison of Fentanyl and Remifentanil

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    Optimal sedation and analgesia are of key importance in intensive care. The aim of this study was to assess the quality of sedoanalgesia and outcome parameters in regimens containing midazolam and either fentanyl or remifentanil. A prospective, randomized, open-label, controlled trial was carried out in the ICU unit of a large teaching hospital in Istanbul over a 9-month period. Thirty-four patients were randomly allocated to receive either a remifentanil-midazolam regimen (R group, n = 17) or a fentanyl-midazolam regimen (F group, n = 17). A strong correlation between Riker Sedation-Agitation Scale (SAS) and Ramsey Scale (RS) measurements was observed. Comparatively, remifentanil provided significantly more potent and rapid analgesia based on Behavioral-Physiological Scale (BPS) measurements and a statistically nonsignificantly shorter time to discharge. On the other hand, remifentanil also caused a significantly sharper fall in heart rate within the first six hours of treatment
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