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As IC technology scales down, interconnect issues are becoming one of the major concerns of gigahertz system-on-chip (SoC) design. Voltage distortion (power supply noise) and delay violations (signal and clock skews) dramatically contribute to signal integrity loss. As a consequence, performance degradation, reliability problems and ultimately, functional error occur. In this paper, we propose a new methodology to enhance SoC signal integrity with respect to power/ground voltage transients, without degrading its performance. The underlying principle of the proposed methodology is to dynamically adapt the clock duty-cycle (CDC) according to the signal propagation delay through the logic whose power supply voltage is being disturbed. The methodology is based on a clock stretching logic (CSL) block, which monitors abnormal power grid activity and increases clock duty-cycle accordingly. Moreover, a model to accurately quantify CDC stretching as a function of VDD/Gnd fluctuations is proposed. Practical experiments based on the implementation of a 32-bit pipeline processor in a FPGA IC were performed and demonstrate the circuit robustness enhancement to power line fluctuations while maintaining at-speed clock rate.

Objectives: Accurate serological assays are urgently needed to support public health responses to Zika virus (ZIKV) infection with its potential to cause foetal damage during pregnancy. Current flavivirus serology for ZIKV infections lacks specificity due to cross-reacting antibodies from closely related other flaviviruses. In this study, we evaluated novel serological tests for accurate ZIKV IgG detection. Methods: Our ELISAs are based on immune complex binding. The high specificity is achieved by the simultaneous incubation of labelled ZIKV antigen and unlabelled flavivirus homolog protein competitors. Two assays were validated with a panel of 406 human samples from PCR-confirmed ZIKV patients collected in Brazil (n = 154), healthy blood donors and other infections from Brazil, Europe, Canada and Colombia (n = 252). Results: The highest specificity (100% [252/252, 95% confidence interval (CI) 98.5-100.0]) was shown by the ZIKV ED3 ICB ELISA using the ED3 antigen of the ZIKV envelope. A similar test using the NS1 antigen (ZIKV NS1 ICB ELISA) was slightly less specific (92.1% [232/252, 95% CI 88.0-95.1]). The commercial Euroimmun ZIKV ELISA had a specificity of only 82.1% (207/252, 95% CI 76.8-86.7). Sensitivity was high (93-100%) from day 12 after onset of symptoms in all three tests. Seroprevalence of ZIKV IgG was analysed in 87 samples from Laos (Asia) confirming that the ED3 ELISA showed specific reactions in other populations. Conclusions: The novel ED3 ICB ELISA will be useful for ZIKV-specific IgG detection for seroepidemiological studies and serological diagnosis for case management in travellers and in countries where other flavivirus infections are co-circulating.

As IC technology scales down, signal integrity issues such as power supply noise and clock skews are becoming one of the major concerns of gigahertz system-on-chip (SoC) design. Considering that one of the most important mechanisms to degrade signal integrity is electromagnetic interference (EMI), this paper analyzes the effectiveness of a clock duty-cycle (CDC) modulation technique to enhance SoC signal integrity with respect to power/ground voltage transients induced by EMI. The technique is based on a clock stretching logic (CSL) block, which monitors abnormal power grid activity and increases CDC accordingly. Practical experiments based on the implementation of a 32-bit soft-core pipeline processor in an FPGA IC were performed and illustrate the circuit robustness enhancement to power line fluctuations while maintaining at-speed clock rate. These experiments were conducted according to the IEC 62.132-2. Normative for measurement of radiated electromagnetic immunity (TEM-cell method).