In view of the recent results of lattice QCD simulation in the P11 partial wave that has found no clear signal for the three-quark Roper state we investigate a different mechanism for the formation of the Roper resonance in a coupled channel approach including the πN, πDelta, and σN channels. We fix the pion-baryon vertices in the underlying quark model while the s-wave sigma-baryon interaction is introduced phenomenologically with the coupling strength, the mass, and the width of the σ meson as free parameters. The Laurent- Pietarinen expansion is used to extract the information about the S-matrix pole. The Lippmann-Schwinger equation for the K matrix with a separable kernel is solved to all orders. For sufficiently strong σNN coupling the kernel becomes singular and a quasibound state emerges at around 1.4 GeV, dominated by the σN component and reflecting itself in a pole of the S matrix. The alternative mechanism involving a (1s)22s quark resonant state is added to the model and the interplay of the dynamically generated state and the three-quark resonant state is studied. It turns out that for the mass of the three-quark resonant state above 1.6 GeV the mass of the resonance is determined solely by the dynamically generated state, nonetheless, the inclusion of the three- quark resonant state is imperative to reproduce the experimental width and the modulus of the resonance pole.

Generally, the probability density function (PDF) of orthogonal frequency division multiplexing (OFDM) signal amplitudes follow the Rayleigh distribution, thus, it is difficult to correctly predict the existence of impulsive noise (IN) in powerline communication (PLC) systems. Compressing and expanding the amplitudes of some of these OFDM signals, usually referred to as companding, is a peak-to-average power ratio reduction technique that distorts the amplitudes of OFDM signals towards a uniform distribution. We suggest its application in PLC systems, such as IEEE 1901 powerline standard (which uses OFDM) to reduce the impacts of IN. This is because the PLC channel picks up impulsive interference that the conventional OFDM driver cannot combat. We explore, therefore, five widely used companding schemes that convert the OFDM signal amplitude distribution to uniform distribution to avail the mitigation of IN in PLC system receivers by blanking, clipping and their hybrid (clipping-blanking). We also apply nonlinear optimization search to find the optimal mitigation thresholds and results show significant improvement in the output signal-to-noise ratio (SNR) for all companding transforms considered of up to 4 dB SNR gain. It follows that the conventional PDF leads to false IN detection, which diminishes the output SNR when any of the above three nonlinear memoryless mitigation schemes is applied.

In view of the recent results of lattice QCD simulation in the P11 partial wave that has found no clear signal for the three-quark Roper state we investigate a different mechanism for the formation of the Roper resonance in a coupled channel approach including the πN , π∆ and σN channels. We fix the pion-baryon vertices in the underlying quark model while the s-wave sigma-baryon interaction is introduced phenomenologically with the coupling strength, the mass and the width of the σ meson as free parameters. The Laurent-Pietarinen expansion is used to extract the information about the S-matrix pole. The Lippmann-Schwinger equation for the K matrix with a separable kernel is solved to all orders. For sufficiently strong σNN coupling the kernel becomes singular and a quasi-bound state emerges at around 1.4 GeV, dominated by the σN component and reflecting itself in a pole of the S-matrix. The alternative mechanism involving a (1s)2s quark resonant state is added to the model and the interplay of the dynamically generated state and the three-quark resonant state is studied. It turns out that for the mass of the three-quark resonant state above 1.6 GeV the mass of the resonance is determined solely by the dynamically generated state, nonetheless, the inclusion of the three-quark resonant state is imperative to reproduce the experimental width and the modulus of the resonance pole.

Ampullary cancer is a rare neoplasm of the pancreaticobiliary tract. Most of the ampullary neoplasms require surgical resection. Cephalic pancreaticoduodenectomy (CPD) has been performed laparoscopically at high-volume institutions worldwide. In this paper, we present a 63-year-old patient with painless jaundice, subjected to proximal endoscopy and biopsy of the lesion located in the papilla of Vater, which resulted in a diagnosis of the adenocarcinoma of the papilla of Vater. We performed laparoscopic CPD with appropriate lymphadenectomy. To the best of our knowledge, this complex and technically challenging surgical procedure is the first of this kind in our country and the region.