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BER performance study for optical OFDM of optical camera communication

In this article, different forms of optical orthogonal frequency division multiplexing (OFDM) were observed which were suitable for optical camera communication (OCC) systems. This research aims to establish the bit error rate (BER) versus signal-to-noise ratio (SNR) of the OCC system. This research will focus on OCC systems and the design that produces the noise of the clipping but will gain SNR as a whole if an optimum clipping factor is chosen. The BER versus SNR analysis was investigated for the different clipping factors 0.7, 1.4, and 2.6. The BER performance of the asymmetrically clipped optical OFDM (ACO-OFDM) was also compared with the direct current optical OFDM (DCO-OFDM) to show the suitable effectiveness of the proposed approach. ACO-OFDM was considered to be better due to lower bit loading, but DCO-OFDM was efficient for higher SNR values. This was because the DC bias used was inefficient in terms of optical capacity, while ACO-OFDM used only half of the subcarriers to transmit the information. Moreover, ACO-OFDM two-dimensional half-subcarriers of mapping rule would introduce the clipping noise to its unused 2D subcarriers, although further data can be provided by the 2D DCO-OFDM mapping rule

Necessity of analgesics prescription after tooth extraction

Introduction. For patients and surgeons, pain and discomfort associated with dento-alveolar surgery can be a frightening prospect. This study was aimed to check whether prescription of analgesics is necessary or not after simple extraction of the mandibular third molars. Material and methods. Seventy-six dental outpatients undergoing uncomplicated extraction of both mandibular third molars teeth served as subjects. After extraction on the first side, patients received either naproxen sodium 550 mg orally or a placebo. The order of the drugs was reversed during extraction on side two. The postoperative pain was scored with a six-point category rating scala. The obtained data were analyzed with Mann-Whitney U-test. Results. The sum of the pain intensity for hours 2 through 8 was less for the group that received sodium naproxen. For hours 8-24, the sum of the pain intensity was less for the placebo group but this difference was not statistically different. Conclusion. This study shows that uncomplicated tooth extraction did not cause a significant postoperative pain and there was no need to prescribe analgesics for such cases