No abstract

A possible way to extract the value for the y parameter in the radiative pion decay is presented through the study of the decay process r r +e + e + e -v . A particular kinematic configuration is suggested to select those events dominated by the structure-dependent contribution without having to perform the difficult measurement on particle polarizations, but retaining the favored picture from the study of a polarized electron in the radiative pion decay rr-e-Fy. A specific positron spectrum is given for this particular configuration to serve as a tentative way of determining an exact value for y between the existing two possible ones.

Critical curves for the soliton-antisoliton annihilation on the infinitely long Josephson junction under the perturbation of bias current, shunt loss, and surface-impedance loss are 'obtained by means of the perturbation theory presented by McLaughlin and Scott. It is demonstrated that the presence of the surface-impedance loss severely reduces the stability of antipolar Auxons, especially when the shunt loss and bias current are small. The results are compared with experiment, and good agreement is found in most cases.

Neurofibromatosis type 1 (NF1) is a dominant hereditary disease characterized by the mutation of the NF1 gene, affecting 1/3000 individuals worldwide. Most NF1 patients are predisposed to benign peripheral nerve sheath tumors (PNSTs), including cutaneous neurofibromas (CNFs) and plexiform neurofibromas (PNFs). However, 5%-10% of PNFs will ultimately develop into malignant peripheral nerve sheath tumors (MPNSTs), which have a poor prognosis. Early and reliable differentiation of benign and malignant tumors in NF1 patients is of great necessity. Pathological evaluation is the “gold standard” for a definite diagnosis, but the invasive nature of the biopsy procedure restricts it from applying as a screening tool during the decades-long follow-up of these patients. Non-invasive image-based diagnostic methods such as CT and MRI are often considered essential screening tools for multiple types of tumors. For NF1 patients’ lifelong regular follow-ups, these radiological methods are currently used for tumor evaluation. However, no consensus was established on screening the malignant transformation of benign PNSTs. Moreover, novel technologies like radiogenomics and PET-MRI have not been well evaluated and fully adopted for NF1 patients. This review summarizes current studies of different imaging methods for differentiating benign and malignant tumors in NF1. Meanwhile, we discussed the prospects of the usage of new tools such as radiogenomics and PET-MRI to distinguish MPNST from benign PNSTs more precisely. Summarizing these findings will help clarify the directions of future studies in this area and ultimately contribute to the radiology images-based clinical screening of MPNST in NF1 patients and finally improve the overall survival rates of these patients.

We give a quantitative account of radiative pion decays. By the chiral structure of the interaction and the fact of the low mass ratio between an electron and a pion, one can suppress the inner-bremsstrahlung contribution and correspondingly enhance the structure-dependent contribution by looking at decays with the emission of a negative-helicity electron. By this observation, we examine a way of determining the value of the structure-dependent parameter y , giving particular attention to the decay spectra with this electron helicity. We also investigate the effects of a neutrino mass in this process.