GaN HEMT DC I-V Device Model for Accurate RF Rectifier Simulation

Recently, various high-efficiency RF rectifiers have been proposed. In this article, to improve the simulation accuracy of RF active rectifier circuits, a new device model for GaN HEMTs is proposed that improves the reproducibility of ID-VDS characteristics in the third-quadrant region (both drain voltage and drain current are negative). Based on measured characteristic data of an actual GaN HEMT, the device parameters for this model have been decided, and the advantage of the new device model has been confirmed

The immunoreceptor adapter protein DAP12 suppresses B lymphocyte–driven adaptive immune responses

Human and mouse B cells lacking functional DAP12 are hyperresponsive, and DAP12 works with MAIR-II (CD300d) to negatively regulate B cell activity

Ferrimagnetism and Ferroelectricity in Cr-Substituted GaFeO₃ Epitaxial Films

GaFeO₃-type iron oxides are promising multiferroic materials due to the coexistence of a large spontaneous magnetization and polarization near room temperature. However, magnetic substitution, which is a general method to control multiferroic properties, is difficult due to instability of the substituted GaFeO₃. In this study, Ga_0.5Cr_0.5FeO₃ epitaxial thin films are successfully fabricated through epitaxial stabilization. These films exhibit in-plane ferrimagnetism and out-of-plane ferroelectricity simultaneously. X-ray absorption spectroscopy and X-ray magnetic circular dichroism measurements of the Ga_0.5Cr_0.5FeO₃ film reveal that the oxidation states of the Fe and Cr ions are trivalent. In addition, some Fe ions are located at tetrahedral Ga1 sites. Compared to the GaFeO₃ film, the Ga_0.5Cr_0.5FeO₃ film shows a higher magnetic phase transition temperature (240 K), weaker saturation magnetization at 5 K, and a unique temperature dependence of the magnetization behavior. The effects of Cr substitution on the magnetic properties are strongly affected by the sites of the Fe³⁺ (3d⁵) and Cr³⁺ (3d³) ions. Furthermore, room-temperature ferroelectricity in the GaFeO₃ and Ga_0.5Cr_0.5FeO₃ films was demonstrated. Interestingly, the change in the ferroelectric parameters via Cr substitution is very small, which disagrees with the previously proposed polarization switching mechanism. Our findings are key to understanding the genuine polarization switching mechanism of the multiferroic GaFeO₃ system

Large mucinous cystic neoplasm of the pancreas associated with pregnancy

Mucinous cystic neoplasms (MCNs) of the pancreas occur mostly in females and are potentially sex hormone-sensitive. However, a MCN occurring during pregnancy is quite rare. A 30-year-old woman in the tenth week of pregnancy was referred to us because of a rapid increase in left hypochondrial distending pain. On ultrasound, the patient had a large intra-abdominal cystic lesion. She was thereafter diagnosed with missed abortion and a computed tomography scan showed that the lesion was a cystic tumor 18 cm in diameter originating from the pancreatic tail. The patient subsequently underwent tumor resection with distal pancreatectomy, sparing the spleen. Histopathological analysis of the specimen revealed a pancreatic MCN with moderate dysplasia. Immunohistochemically, the tumor was positive for both estrogen and progesterone receptors. To our knowledge, this is the first reported case of pancreatic MCN with moderate dysplasia in association with pregnancy. Our case strongly indicates that pancreatic MCN is female-hormone dependent