25,502 research outputs found

    Signal Detection for QPSK Based Cognitive Radio Systems using Support Vector Machines

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    Cognitive radio based network enables opportunistic dynamic spectrum access by sensing, adopting and utilizing the unused portion of licensed spectrum bands. Cognitive radio is intelligent enough to adapt the communication parameters of the unused licensed spectrum. Spectrum sensing is one of the most important tasks of the cognitive radio cycle. In this paper, the auto-correlation function kernel based Support Vector Machine (SVM) classifier along with Welch's Periodogram detector is successfully implemented for the detection of four QPSK (Quadrature Phase Shift Keying) based signals propagating through an AWGN (Additive White Gaussian Noise) channel. It is shown that the combination of statistical signal processing and machine learning concepts improve the spectrum sensing process and spectrum sensing is possible even at low Signal to Noise Ratio (SNR) values up to -50 dB

    Chiral transition in a magnetic field and at finite baryon density

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    We consider the quark-meson model with two quark flavors in a constant external magnetic field BB at finite temperature TT and finite baryon chemical potential μB\mu_B. We calculate the full renormalized effective potential to one-loop order in perturbation theory. We study the system in the large-NcN_c limit, where we treat the bosonic modes at tree level. It is shown that the system exhibits dynamical chiral symmetry breaking, i. e. that an arbitrarily weak magnetic field breaks chiral symmetry dynamically, in agreement with earlier calculations using the NJL model. We study the influence on the phase transition of the fermionic vacuum fluctuations. For strong magnetic fields, qB5mπ2|qB|\sim5m_{\pi}^2 and in the chiral limit, the transition is first order in the entire μBT\mu_B-T plane if vacuum fluctuations are not included and second order if they are included. At the physical point, the transition is a crossover for μB=0\mu_B=0 with and without vacuum fluctuations.Comment: 11 pages. 5figs. V2: fixed a few typos and added refs. Submitted to PRD. V3: Added refs and substantial revision of tex

    Entanglement and Bell's inequality violation above room temperature in metal carboxylates

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    In the present work we show that a special family of materials, the metal carboxylates, may have entangled states up to very high temperatures. From magnetic susceptibility measurements, we have estimated the critical temperature below which entanglement exists in the cooper carboxylate \{Cu2_2(O2_2CH)4_4\}\{Cu(O2_2CH)2_2(2-methylpyridine)2_2\}, and we have found this to be above room temperature (Te630T_e \sim 630 K). Furthermore, the results show that the system remains maximally entangled until close to 100\sim 100 K and the Bell's inequality is violated up to nearly room temperature (290\sim 290 K)

    Why Patients Need Protection From the Sun

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    Sunlight has been thought to be beneficial in recent decades, a time in which widespread tanning has become the norm. However, some patients’ quest for the perfect tan may lead them to permanent disfigurement and early death due to the damaging effects of ultraviolet (UV) radiation

    An Update on BRAF Inhibitors and Other New Molecular Targets for the Treatment of Malignant Melanoma of the Skin

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    Malignant melanoma of the skin originates from mutations in melanocytes and can be lethal if unrecognized or untreated in its earlier stages. Deaths from melanoma are increasing in the United States and around the world every year. The available treatments produce low rates of response with modest survival impact. Among potential molecular targets under investigation, which are mostly in the tyrosine kinase pathway, the BRAF (V-raf murine sarcoma viral oncogene homolog B1) gene is the best studied and most frequently reported mutation in melanoma. The molecular targets for melanoma treatment, promising drugs for future melanoma treatment as well as the new molecular entities that are approved are reviewed here. Approved by FDA in 2011, vemurafenib (Zelboraf) is the first personalized targeted therapy for treatment of metastatic melanoma that acts by selectively inhibiting BRAFV600E. This has opened a new avenue for the discovery of targeted drug therapies for melanoma based on the principles of pharmacogenomics

    Chiral symmetry and the axial nucleon to Delta(1232) transition form factors

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    We study the momentum and the quark mass dependence of the axial nucleon to Delta(1232) transition form factors in the framework of non-relativistic chiral effective field theory to leading-one-loop order. The outcome of our analysis provides a theoretical guidance for chiral extrapolations of lattice QCD results with dynamical fermions.Comment: 18 pages, 3 figure
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