Search

Wide band gap (WBG) semiconductors, such as gallium nitride (GaN), have become popular among switching power modules. In pursuing power conversion efficiency, power module’s high-speed and high-power operation leads to electromagnetic (EM) noise in a very wide frequency range, potentially interfering with nearby wireless communications [e.g., long-term evolution (LTE)]. This letter analyzes the source of EM noise from the power modules using GaN transistors in half-bridge circuits. EM noise was clearly observed in the proximity of power modules and attributed to two primary sources in the frequency range of interest up to 6 GHz: 1) the periodical switching operation of GaN transistors in the output stage and 2) the logic operation of complementary metal–oxide–semiconductor digital circuits to control gate drivers, in the lower and upper side of frequencies, respectively. Measurements analyzed the EM noise characteristics at different probing locations over the assembly of two GaN power modules as well as in different operating conditions by strategically supplying source signals. The influence of EM noise on LTE receiver performance is evaluated with wireless system-level simulation and related to the degradation of its minimum receivable input power.

Crithidia mellificae (C. mellificae) and Lotmaria passim (L. passim) are trypanosomatids that infect Apis mellifera. We analyzed the prevalence of C. mellificae and L. passim in six regions of Japan from 2018 to 2019. The detection rate of C. mellificae was 0.0% in all regions, whereas L. passim was detected in 16.7%-66.7% of the honeybees. L. passim was detected at a significantly lower rate in the Cyugoku-Shikoku region than in other regions. Furthermore, phylogenetic analysis of the internal transcribed spacer 1 (ITS1) locus of related species was performed. All the samples in this study could be assigned to the L. passim clade. This study reveals that L. passim infection is predominantly prevalent in Japan. Further epidemiological surveys are needed to clarify the prevalence of C. mellificae infection in honeybees in Japan.

[Purpose] The objective of this study was to provide cerebral stroke patients with virtual reality videos of gait occurring at a faster speed than their actual measured gait speed and ascertain the effect on generating errors of gait. [Participants and Methods] The participants were 12 stroke patients. They were given a 2-minute virtual reality presentation of gait occurring at a speed faster than their actual measured comfortable walking speed. Immediately following the presentation, their 10-m walking speed was measured again to observe the immediate effect of the intervention, after which the time required to walk at maximum gait speed was measured. Stride length, cadence, and walking speed before and after the intervention were compared. In addition, heard an immersive feeling. [Results] At a comfortable walking speed, the cadence improved significantly post-intervention. Walking speed and stride length also tended to increase. At the maximum walking speed, there were no significant differences in any parameter. There was no problem with the immersive feeling. [Conclusion] After watching virtual reality videos of gait at a speed faster than the patients' actual gait speed, their walking speed tended to increase in comfortable walking. It was speculated that this technique could be applied to walking training, depending on the device.

Unmanned aerial vehicles (UAVs) have been penetrated into various markets. The control through cellular communication channels becomes of significant importance to ensure safely flying above densely populated areas. UAV s may suffer from electromagnetic interference (EMI) problems where their airframe is densely packed in a compact chassis with multiple electronic modules for power, control, and wireless communications. This paper describes the experiments on Electromagnetic (EM) emission within a compact (hobby or home) drone and the potentiality of EMI among the control and wireless modules once integrated in the same chassis. The EM waves were measured between 500 MHz and 6 GHz, with a folded long-hexagon antenna at 200 mm away from the drone in an anechoic box. It was observed that the drone emanated the EM waves up to -151 dBm/Hz in 800 MHz band. The influence on cellular communication performance was evaluated with a wireless communication system level simulator, showing the degradation by at most 15 dB in the minimum sensitivity if a receiver module exists in the same aircraft.

The spread of undesired radio waves and the development of semiconductor switching devices causes serious noise interference in wireless communication systems. We introduce a system to evaluate the noise interference caused by such switching devices with high resolution. Our evaluation system consists of two parts: a high-resolution noise measurement system and an evaluation of wireless communication performance by system level simulations. The integrated power of undesired radio waves is measured within a 5-MHz bandwidth and can be detected even at an ultra-low power level of −177 dBm/Hz. The lower detection limit of the undesired radio waves is enough to evaluate the impact on wireless communication performance. We evaluated undesired radio waves from a wireless power transfer (WPT) system for charging electric vehicles. In our simulation, at the 840-MHz band, we observed an undesired radio waves level of −143 dBm/Hz near the WPT system that degraded the long-term evolution (LTE) sensitivity to −74 dBm/5 MHz.

Magnetic composite sheets of ferrite powders suppressed the undesired RF electromagnetic noise emission in a flip-chip semiconductor IC chip package. Their effects were evaluated by the measurements with Si demonstrators and the improvements on wireless communication performance were simulated at the wireless system level. The effectiveness was found to be dependent on the composites -- BaZn-Y hexagonal ferrites exhibited noise suppression by 7dB, which corresponded to the wireless performance improvements by 8dB in the 800 MHz band when the long term evolution (LTE) wireless system is assumed.

NiCuZn spinel ferrite particles were sintered into 50 μm-thick plate and mounted in between IC die and its interposer to explore their suitability as electromagnetic noise suppressor up to 10 GHz. A 50 μm thick Y-Type hexaferrite plate with density of 5.2 g/cm3 exhibits the figure-of-merit, Ploss/Pin, as high as 0.27 at 7 GHz. The test ferrite plate was embedded in between IC chip and interposer using a newly developed pre-assembly technique. This was enough to suppress on-chip conduction noise and corresponding near field emission by 4-17 dB in wireless communication channels.

Near-field undesired radio waves are measured for electronic systems of interest that involve semiconductor switching circuits, and recorded in a noise database for evaluation of wireless interference at different locations or even in later developments of wireless terminals. Undesired radio waves are restored from the database as if a wireless terminal is placed nearby noise emitting systems, and analyzed with regard to their interference to wireless communication channels by using fully behavioral or hardware-in-the-loop simulation of wireless systems. A wireless power transfer (WPT) system for contactless charging of the batteries on electric vehicles (EVs) utilizes high-speed switching transistors for power converters/inverters as well as for digital controllers with switching logic circuits. The near field undesired radio waves recorded on-site at an anechoic chamber exhibit clear impacts on the data throughput of long-term evolution (LTE) wireless channel in off-site wireless system simulation with playback from the noise database.

Background Recently, endoscopic submucosal dissection (ESD) has been used as a less invasive treatment for superficial esophageal cancer. Additional treatment is often required after non-curative resection to prevent local recurrence and lymph node metastasis. Here, we present the outcomes of various additional treatments for patients with superficial esophageal cancer who underwent ESD. Methods Between 2006 and 2017, we performed ESD in 179 patients (210 lesions) with superficial esophageal cancer and 44 cases resulted in the non-curative resection diagnosed by the pathological examination. Among them, 29 patients received additional treatment, whereas 15 patients with no additional treatment were followed up. Additional treatment included esophagectomy (8 patients), chemoradiotherapy (15 patients), ablation using argon plasma coagulation (4 patients), and chemotherapy alone (2 patients). We examined the clinicopathological characteristics and prognosis of patients in the additional esophagectomy group (S group) and chemoradiotherapy group (CRT group). Results Twenty-three patients with pT1a-MM, pT1b, lymphatic invasion, venous invasion, and positive resection margins (both horizontal and vertical) were divided into two treatment groups. Clinicopathological characteristics of patients in the S and CRT groups were not significantly different. Pathological findings after additional esophagectomy showed one residual tumor and one lymph node metastasis. There were no recurrences in the two groups. There was no statistically significant difference in the 5-year overall survival rate between the S group (87.5%) and the CRT group (93.3%). One patient from the S group died due to respiratory pneumonia, and one patient died due to radiation pneumonia. However, five out of the 15 (33.3%) patients who were followed up with no additional treatment developed recurrence. The 5-year overall survival rate was 40.4%, which was not significantly different from that in the additional treatment group. However, the 5-year relapse-free survival rate (30%) was significantly different from that in the additional treatment group (P > 0.05). Conclusion Additional treatment is essential after non-curative endoscopic submucosal resection for esophageal cancer. Additional esophagectomy and chemoradiotherapy were both safe and effective in this cohort. Disclosure All authors have declared no conflicts of interest.

We report the case of a 28-year-old woman with type B chronic aortic dissection extending from a ductus diverticulum aneurysm. The patient was successfully treated by interposition of a Hemashield 26-mm woven Dacron graft with a left posterolateral thoracotomy approach. Circulatory arrest through profound hypothermia and short retrograde cerebral circulation were employed during proximal anastomosis of the graft.

Itoi T, Sofuni A, Itokawa F, et al. Initial experience with a prototype peroral direct cholangioscope to perform intra-ductal lithotripsy (with video). Gastrointest Endosc 2011;73:841-3. . Larghi A, Waxman I. Endoscopic direct cholangioscopy by using an ultraslim upper endoscope: a feasibility study. Gastrointest Endosc 2006;63: 853-7. . Moon JH, Ko BM, Choi HJ, et al. Intraductal balloon guided direct peroral cholangioscopy using an ultra-slim upper endoscope. Gastrointest Endosc 2009;70:297-302. . Tsou YK, Lin CH, Tang JH, et al. Direct peroral cholangioscopy using an ultraslim endoscope and overtube balloon-assisted technique: a case series. Endoscopy 2010;42:681-4. . Waxman I, Dillon T, Chmura K, et al. Feasibility of a novel system for intraductal balloon-anchored direct peroral cholangioscopy and endotherapy with an ultraslim endoscope (with videos). Gastrointest Endosc 2010;72:1052-6.

We previously reported that liposomalized 5′-O-dipalmitoylphosphatidyl 2′-C-cyano-2′-deoxy-1-β-D-arabino-pentofuranosylcytosine (DPP-CNDAC), a hydrophobized derivative of the novel antitumor nucleoside CNDAC, is quite useful for cancer therapy. On the other hand, for anti-neovascular therapy, we recently isolated peptides homing to angiogenic vessels from a phage-displayed random peptide library, and observed that peptide-modified liposomal adriamycin strongly suppressed tumor growth, perhaps through damaging angiogenic endothelial cells. In the present study, we modified DPP-CNDAC-liposomes with one of the angiogenic homing peptides, APRPG, and examined their antitumor activity. Three doses of APRPG-modified DPP-CNDAC-liposomes (15 mg/kg as CNDAC) strongly inhibited tumor growth compared with the same number of doses of unmodified DPP-CNDAC-liposomes. The life span was increased 31.8%, with one completely cured mouse out of the six mice treated. Since the accumulation of liposomes in the tumor tissue was not so much different between APRPG-liposomes and non-modified liposomes, the enhanced therapeutic efficacy may be explained as the alteration of targets, i.e. APRPG-modified DPP-CNDAC-liposomes caused tumor growth suppression through damage of angiogenic endothelial cells. Anti-neovascular therapy promises no drug resistance, and should be effective against essentially any kind of solid tumor; and thus the present results demonstrate another benefit of the therapy, namely, high efficacy of cancer treatment.

Cancer chemotherapy targeted to angiogenic vessels is expected to cause indirect tumor regression through the damage of the neovasculature without the induction of drug resistance. To develop a tool for neovasculature-specific drug delivery, we isolated novel peptides homing to angiogenic vessels formed by a dorsal air sac method from a phage-displayed peptide library. Three distinct phage clones that markedly accumulated in murine tumor xenografts presented PRPGAPLAGSWPGTS-, DRWRPALPVVLFPLH- or ASSSYPLIHWRPWAR-peptide respectively. After the determination of the epitope sequences of these peptides, we modified liposomes with epitope penta-peptides. Liposome modified with APRPG-peptide showed high accumulation in murine tumor xenografts, and APRPG-modified liposome encapsulating adriamycin effectively suppressed experimental tumor growth. Finally, specific binding of APRPG-modified liposome to human umbilical endothelial cells, and that of PRP-containing peptide to angiogenic vessels in human tumors, i.e., islet cell tumor and glioblastoma, were demonstrated. The present study indicates the usefulness of APRPG-peptide as a tool for anti-neovascular therapy, a novel modality of cancer treatment.

The recombinase activation genes, RAG-1 and RAG-2, are expressed together in immature T or B lymphocytes and possess activity to induce V(D)J rearrangement in T cell receptor (TCR) and Ig genes. In vertebrates, only Ig and TCR molecules are reported to have recombination in their development using multiple V, D, J component gene segments. Thus, expression of RAG genes are localized only in lymphoid organs and sites of extrathymic T cell differentiation. In this study, we have used RAG-1 and RAG-2 genes as markers of possible genetic recombination in developing murine preimplantation embryos, using the highly sensitive reverse transcriptase polymerase chain reaction (RT-PCR) technique and in situ hybridization. From 40 preimplantation embryos of various developmental stages we extracted RNA, reverse-transcribed it into cDNA and used it in RT-PCR studies. A PCR of 35 cycles disclosed expression of RAG-1 but not RAG-2 in morulae and blastocysts. Southern blot hybridization using a specific synthetic oligonucleotide probe for RAG-1 and RT-PCR with another primer pair identified RAG-1 expression in developing embryos. In situ hybridization using a cooled CCD camera also revealed localization of RAG-1 mRNA in blastocysts. We propose possible genetic recombination during late preimplantation murine embryogenesis which may contribute to the loss of totipotency and differentiation of inner cell mass and trophoectoderm.