Design and analysis for the SPICE parameters of waveform-selective metasurfaces varying with the incident pulse width at a constant oscillation frequency.

In this study, we numerically demonstrate how the response of recently reported circuit-based metasurfaces is characterized by their circuit parameters. These metasurfaces, which include a set of four diodes as a full wave rectifier, are capable of sensing different waves even at the same frequency in response to the incident waveform, or more specifically the pulse width. This study reveals the relationship between the electromagnetic response of such waveform-selective metasurfaces and the SPICE parameters of the diodes used. In particular, we draw conclusions about how the SPICE parameters are related to (1) the high-frequency operation, (2) input power requirement and (3) dynamic range of waveform-selective metasurfaces with supporting simulation results. First, we show that reducing a parasitic capacitive component of the diodes is important for realization of the waveform-selective metasurfaces in a higher frequency regime. Second, we report that the operating power level is closely related to the saturation current and the breakdown voltage of the diodes. Moreover, the operating power range is found to be broadened by introducing an additional resistor into the inside of the diode bridge. Our study is expected to provide design guidelines for circuit-based waveform-selective metasurfaces to select/fabricate optimal diodes and enhance the waveform-selective performance at the target frequency and power level. Our results are usefully exploited to ensure the selectivity based on the pulse duration of the incident wave in a range of potential applications including electromagnetic interference, wireless power transfer, antenna design, wireless communications, and sensing.

History of malignant neoplasia lessens oocyte developmental competence: a case-control study.

OBJECTIVE: We investigated how history of malignant neoplasia affected oocyte developmental competence. METHODS: Fifty-two cycles of assisted reproductive technology (ART) in women with a history of malignant disease (case group) were compared with fifty-two matched cycles of ART in women with no cancer history (control group). Propensity score matching involving age and body mass index was used to select controls. Oocyte developmental competence and rates of pregnancy and livebirth were compared as main outcomes. To investigate whether the cancer itself had affected oocyte developmental competence, this outcome variable was compared between case cycles with and without cancer surgical histories. RESULTS: Numbers of fertilized oocytes (FO), cleaving embryos (CE), and superior CE (SCE) were significantly lower in cases than controls. Rates of fertilization and of development to SCE from retrieved oocytes (RO), FO, or CE also were lower in cases than controls (63, 25, 39, and 43% vs. 72, 36, 50, and 55%, respectively). Cases had significantly lower rates of clinical pregnancy and livebirth per embryo transfer than controls (7.6 and 1.5% vs. 20.4 and 14.0%). Rates of development to SCE from RO, FO, and CE showed no significance for differences between cases with and without cancer operations (22, 37, and 40% vs. 31, 42, and 49%). CONCLUSIONS: A woman's history of malignant neoplasia was associated with decreased oocyte developmental competence, possibly related to patient's background factors predisposing to tumor.