Signals and Sysytems

In this paper, i elucidated a convolution integral by exploiting linearity and time invariance properties of LTI system. Next, Fourier and Laplace Transforms are introduced and their important property (which states that transform of convolution is multiplication in both frequency and s domain) is derived. Furthermore, some typical applications using FT and LT are considered

Semiotics is the study of signs. Signs are considered as anything which stands for something else other than itself. Many studies have been done on semiotics. However, studies on semiotics on Nandi culture are scarce. Since the interpretations of signs are limited to the cultural context, there was a need to study semiotics used in Nandi social events. This study therefore sought to analyze the signs used in Nandi social events. The objectives of the study were: first to find out the signs used in Nandi social events; second to explain the meanings of signs used in Nandi social events; finally, to describe the relativity of signs used in Nandi social events. The study was grounded on Charles Sanders Peirce's (1860) semiotic theory which offers a triadic model which consists of the form commonly referred to a sign vehicle, the sense made of the sign, and an object commonly referred to as a referent. This study adopted a descriptive qualitative research design. The study was grounded in Pierce triangle theory. The population comprised Nandi speakers aged between 40 and 60 years living in Megun ward, Kapseret Constituency, Uasin Gishu County. This age range was important because they have more knowledge on the cultural signs and symbols among the Nandi as compared to younger groups who may not be very conversant with the signs and symbols found in Megun Ward, Kapseret Sub-county Uasin Gishu County Kenya. Uasin Gishu County was chosen for its richness in the cultural practices which have been preserved in its original state as compared to Nandi which has become more cosmopolitan with different borders that seem to have influenced some of the signs and symbols used during different ceremonies. The study adopted the purposive sampling in selecting the participants. These participants engaged in semi-structured interviews with the researcher where they discussed their experiences of the use of signs in social events. Participant observation was also done to identify the signs used and how they were interpreted. A pilot test was carried out in Chepyakwai village, Kapseret ward which has similar characteristic to Megun ward. Data obtained was organized, coded and analyzed using qualitative method. The researcher first identified the signs by sorting them out from the data collected. The signs were analyzed using the semiotic theory which is the study of signs. In order to decode the meanings of the different signs found, the study used Pierce triangle theory. This triadic model was used to illustrate the relationship between the sign and what it represents. This relationship between the signifier and the signified was further analyzed to establish the typology of the signs. This was done using Pierce's tripartite classification: symbolic relationship, iconic relationship and indexical relationship. The results of the research show that there are several signs used in Nandi social ceremonies. These signs used in Nandi social events have different meaning. The study classified the various signs into symbols, icons and indexes. The study helps understand how signs impact interlocutors in Kenyan socio-cultural events and as such, helps to lay a foundation for future research in this area. This study also complements the available research conducted in the area of semiotics. The study recommended that language planners must come up with programmes to promote African indigenous languages in order to promote understanding of signs used in public functions and to address issues of miscommunication in intercultural set ups.

Obstructive sleep apnea (OSA) is one of the most widespread respiratory diseases today. Complete or relative breathing cessations due to upper airway subsidence during sleep is OSA. It has confirmed potential influence on Covid-19 hospitalization and mortality, and is strongly associated with major comorbidities of severe Covid-19 infection. Un-diagnosed OSA may also lead to a variety of severe physical and mental side-effects. To score OSA severity, nocturnal sleep monitoring is performed under defined protocols and standards called polysomnography (PSG). This method is time-consuming, expensive, and requiring professional sleep technicians. Automatic home-based detection of OSA is welcome and in great demand. It is a fast and effective way for referring OSA suspects to sleep clinics for further monitoring. On-line OSA detection also can be a part of a closed-loop automatic control of the OSA therapeutic/assistive devices. In this paper, several solutions for online OSA detection are introduced and tested on 155 subjects of three different databases. The best combinational solution uses mutual information (MI) analysis for selecting out of ECG and SpO2-based features. Several methods of supervised and unsupervised machine learning are employed to detect apnoeic episodes. To achieve the best performance, the most successful classifiers in four different ternary combination methods are used. The proposed configurations exploit limited use of biological signals, have online working scheme, and exhibit uniform and acceptable performance (over 85%) in all the employed databases. The benefits have not been gathered all together in the previous published methods.