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Summary A wide‐range direct digital frequency synthesizer (DDS) is considered an essential component that is used in measuring electrochemical impedance spectroscopy (EIS). Since it depends on exciting the electrochemical sensor by a pure sine wave, total harmonic distortion (THD) is considered a challenging specification for an accurate EIS measurement. This paper introduces a complete system and circuit designs of a wide range DDS with a comprehensive system model using MATLAB environment. In addition, it presents the usage of a reconfigurable digital‐to‐analog converter (DAC) on the circuit level that is used either as a 4‐bit delta‐sigma ( ΔΣ$$ \Delta \Sigma $$) DAC or an 8‐bit binary‐weighted DAC for both low‐ and high‐frequency ranges, respectively. The designed DDS generates an output frequency range from 762.933 Hz to 10 MHz using a physical 8‐bit DAC. The circuits are simulated using 0.18 μm CMOS technology. The designed DDS system achieves THD less than 0.05% with superior free dynamic range (SFDR) 66 dBc for low‐frequency range and 0.08% with SFDR 62 dBc for high‐frequency range. The DDS circuits occupy an area of 400  × 800 μm. The whole system consumes a 2.5 mW power consumption from a 1.8 V supply. [ABSTRACT FROM AUTHOR]

This paper aims at introducing an insight into the nature of cultural conflict as depicted in Chinua Achebe's "Things Fall Apart." This study shows how the African black culture represented by Ibo tribe comes into disagreement with the white one imposed by the British imperialism. The greatness of Achebe lies in the vivid description of place which is Nigeria and people who are the native Africans and how he was able to show the inner conflict that took place inside the major characters, like Okonkwo, in their pursuit of mere existence within a declining culture in the face of a tyrannical white one. The conflict has two aspects; an internal which can be traced within the same culture among its members and sometimes inside a specific character, on the other hand an external conflict took place between two cultures the African and the British one. The pursuit of mere existence is the dominant theme within this novel. It may be argued that Okonkwo's pursuit of existence represents the African culture itself in its endeavor for survival in the face of a domineering British one. Despite the fact that Okonkwo dies at the end, but it is quite evident that the African culture continued its struggle for existence in the hearts and minds of the new generation. All search for existence whether on individual level or cultural level.

With the emergence of one of this century's deadliest pandemics, coronavirus disease (COVID-19) has an enormous effect globally with a quick spread worldwide. This made the World Health Organization announce it as a pandemic. COVID-19 has pushed countries to follow new behaviors such as social distancing, hand washing, and remote work and to shut down organizations, businesses, and airports. At the same time, white hats are doing their best to accommodate the pandemic. However, while white hats are protecting people, black hats are taking advantage of the situation, which creates a cybersecurity pandemic on the other hand. This paper discusses the cybersecurity issues at this period due to finding information or finding another related research that had not been discussed before. This paper presents the cybersecurity attacks during the COVID-19 epidemic time. A lot of information has been collected from the World Health Organization (WHO), trusted organizations, news sources, official governmental reports, and available research articles. This paper then classifies the cybersecurity attacks and threats at the period of COVID-19 and provides recommendations and countermeasures for each type. This paper surveys the cybersecurity attacks and their countermeasures and reports the ongoing cybersecurity attacks and threats at this period of time. Moreover, it is also a step towards analyzing the efficiency of the country's infrastructure as well as hackers and criminals' social behavior at the time of the pandemic., Author(s): Rabie A. Ramadan (corresponding author) [1,2]; Bassam W. Aboshosha [3]; Jalawi Sulaiman Alshudukhi [1]; Abdullah J. Alzahrani [1]; Ayman El-Sayed [4]; Mohamed M. Dessouky [4,5] 1. Introduction Humanity has [...]