Data Fusion Methods for Indoor Positioning Systems Based on Channel State Information Fingerprinting.

Indoor signals are susceptible to NLOS propagation effects, multipath effects, and a dynamic environment, posing more challenges than outdoor signals despite decades of advancements in location services. In modern Wi-Fi networks that support both MIMO and OFDM techniques, Channel State Information (CSI) is now used as an enhanced wireless channel metric replacing the Wi-Fi received signal strength (RSS) fingerprinting method. The indoor multipath effects, however, make it less robust and stable. This study proposes a positive knowledge transfer-based heterogeneous data fusion method for representing the different scenarios of temporal variations in CSI-based fingerprint measurements generated in a complex indoor environment targeting indoor parking lots, while reducing the training calibration overhead. Extensive experiments were performed with real-world scenarios of the indoor parking phenomenon. Results revealed that the proposed algorithm proved to be an efficient algorithm with consistent positioning accuracy across all potential variations. In addition to improving indoor parking location accuracy, the proposed algorithm provides computationally robust and efficient location estimates in dynamic environments. A Cramer-Rao lower bound (CRLB) analysis was also used to estimate the lower bound of the parking lot location error variance under various temporal variation scenarios. Based on analytical derivations, we prove that the lower bound of the variance of the location estimator depends on the (i) angle of the base stations, (ii) number of base stations, (iii) distance between the target and the base station, djr (iv) correlation of the measurements, ρrjai and (v) signal propagation parameters σC and γ.

Heterogeneous Transfer Learning for Wi-Fi Indoor Positioning Based Hybrid Feature Selection.

This paper presents the application of heterogeneous transfer learning (HetTL) methods which consider hybrid feature selection to reduce the training calibration effort and the noise generated by fingerprint duplicates obtained from multiple Wi-Fi access points. The Cramer-Rao Lower Bound analysis (CRLB) was also applied to evaluate and estimate a lower limit for the variance of a parameter estimator used to analyze positioning performance. We developed two novel algorithms for feature selection in fingerprint-based indoor positioning problems (IPP) to enhance positioning performance in the target domain with the HetTL. The algorithms comprised two scenarios: (i) a principal component analysis-based approach (PCA-based) and (ii) a hybrid approach that takes both PCA and correlation effect analysis into account (hybrid scenario). Accordingly, a new feature vector was constructed by retaining only the most significant predictors, and the most efficient feature dimensions were also determined by using a hybrid-based approach. Experimental results showed that the hybrid-based proposed algorithm has the minimum mean absolute error. The CRLB analysis also showed that the number of Wi-Fi access points could affect the lower bound location estimation error; however, identifying the most significant predictors is an effective approach to improve positioning performance.

OHetTLAL: An Online Transfer Learning Method for Fingerprint-Based Indoor Positioning.

In an indoor positioning system (IPS), transfer learning (TL) methods are commonly used to predict the location of mobile devices under the assumption that all training instances of the target domain are given in advance. However, this assumption has been criticized for its shortcomings in dealing with the problem of signal distribution variations, especially in a dynamic indoor environment. The reasons are: collecting a sufficient number of training instances is costly, the training instances may arrive online, the feature spaces of the target and source domains may be different, and negative knowledge may be transferred in the case of a redundant source domain. In this work, we proposed an online heterogeneous transfer learning (OHetTLAL) algorithm for IPS-based RSS fingerprinting to improve the positioning performance in the target domain by fusing both source and target domain knowledge. The source domain was refined based on the target domain to avoid negative knowledge transfer. The co-occurrence measure of the feature spaces (Cmip) was used to derive the homogeneous new feature spaces, and the features with higher weight values were selected for training the classifier because they could positively affect the location prediction of the target. Thus, the objective function was minimized over the new feature spaces. Extensive experiments were conducted on two real-world scenarios of datasets, and the predictive power of the different modeling techniques were evaluated for predicting the location of a mobile device. The results have revealed that the proposed algorithm outperforms the state-of-the-art methods for fingerprint-based indoor positioning and is found robust to changing environments. Moreover, the proposed algorithm is not only resilient to fluctuating environments but also mitigates the model's overfitting problem.

Prevalence, causes and outcomes of war-related civilian injuries in Ethiopia's war-torn Tigray region: a community-based descriptive study.

OBJECTIVE: War and armed conflicts are the major causes of mortality, morbidity and disability. This study was aimed at assessing the prevalence of injury, cause and its outcome among civilians during the war in Tigray, Northern Ethiopia. RESULTS: A community based cross sectional study was conducted to collect data from a total of 4,381 sample households. Descriptive analysis was applied and the data are presented using frequencies, percentages, tables and statements. Of the study participants, 6.9% (95% CI: 6.2%, 7.6%) of civilians encountered any kind of war-related physical injury. About Two-third (95% CI: 59%, 73%) of the physical injuries were caused by bullet followed by heavy artillery shelling (proportion = 23%; 95% CI: 17%, 29%). Painfully, about 44% (95% CI: 37%, 50%) faced death following injuries and the other 56.2% (95% CI: 50%, 62.5%) either survived or encountered disability. Post war rehabilitation for the disabled is recommended to enable them live healthy, dignified, independent and productive citizens.

Magnitude of Overweight and Obesity and Associated Factors Among Public and Private Secondary School Adolescent Students in Mekelle City, Tigray Region, Ethiopia, 2019: Comparative Cross-Sectional Study.

BACKGROUND: Overweight and obesity emerged as one of the most serious public health concerns in adolescents. Overweight and obesity are problems of not only high income but also low-middle income countries. Therefore, this study aimed to assess the magnitude and associated factors of overweight and obesity among public and private secondary school adolescents in Mekelle city, Tigray, Ethiopia, 2019. MATERIALS AND METHODS: A school-based comparative cross-sectional study was conducted in Mekelle city, from April to May 2019. A multi-stage sampling technique was used to select 858 participants. Chi-square test was checked before bivariate logistic regression analyses. All variables at a p-value <0.25 in bivariate logistic regression were entered into a multivariable logistic regression to determine the association between a set of independent variables with the dependent variable. Finally, statistical significance was declared at a p-value <0.05. RESULTS: The magnitude of overweight and obesity in private and public schools were 11.8% and 3.9%, respectively. Consuming dinner not daily [AOR=5.3:95% CI=1.93-14.6] and working moderate-intensity sports at least 10 minutes/day continuously [AOR=0.19:95% CI=0.04-0.9] were associated factors of overweight and obesity in public school adolescent students. Being female [AOR=2.03:95% CI=1.08-3.8], time taken from home to public physical activities ≤15 minutes [AOR=3.6:95% CI=1.13-11.51], using transport from school to home [AOR=2.2:95% CI=1.06-4.18] and good knowledgeable adolescents [AOR=0.5:95% CI=0.27-0.9] were associated factors of overweight and obesity in private schools. CONCLUSION: The magnitude of overweight and obesity was higher among private schools. Consuming dinner not daily and working moderate-intensity sports at least 10 minutes/day continuously were the associated factors for the occurrence of overweight and obesity in public school adolescent students. Being female, time taken from home to public physical activity facilities ≤15 minutes, using transport from school to home, and nutritional knowledge status of adolescents were associated factors for overweight and obesity in private school adolescent students.

Ankle and Foot Pain and Associated Factors Among Nurses at Ayder Comprehensive Specialized Hospital, Mekelle, Ethiopia: Cross-Sectional Study.

BACKGROUND: Ankle-foot pain is a significant public health problem in nurse professionals and has great burdens to the individuals, healthcare systems, and community at large. However, there is limited evidence on the prevalence of ankle-foot pain and its associated factors among nurses in Ethiopia. Thus, the finding of this study will help to address health problems resulting from ankle-foot pain among nurses. PURPOSE: The aim of this study was to determine the prevalence and associated factors of ankle-s-foot pain among nurse working in Ayder Comprehensive Specialized Hospital, Tigray, Ethiopia. PATIENTS AND METHODS: An institutional-based cross-sectional study was conducted on a total of 366 nurses, and a simple random sampling technique was used to recruit study participants. Data were collected by using a self-administered adapted standardized Nordic questionnaire. Descriptive statistics and a bivariate logistic regression model were done to identify factors associated with ankle-foot pain. Those variables with a P-value less than 0.05 with 95% CI in multivariate model were taken as statistically significant. Finally, AOR with 95% confidence interval at a P-value of <0.05 was reported. RESULTS: The prevalence of self-reported ankle-foot pain among nurses was 43.7% (95% CI=38.5-49.1). Older age (AOR=7.669, 95% CI=2.316-25.390), low shoe comfort (AOR=4.215, 95% CI=2.031-8.745), multiple foot conditions (AOR=6.102 95% CI=1.959-19.008), working night shifts (AOR=2.047, 95% CI=1.098-3.816), high physical demand (AOR=3.487, 95% CI=1.988-6.116), and nurses working in the intensive care unit (AOR=2.402, 95% CI=1.219-4.732) showed a statistically significant association with ankle-foot pain. CONCLUSION: This study indicated that the prevalence of ankle-foot pain is commonly reported among nurses working in Ayder Comprehensive Specialized Hospital. Therefore, awareness and prevention of ankle and foot pain in nurses should be prioritized to reducing risk factors. Nurses should give attention to comfortable footwear, and further longitudinal research is recommended.

Assessment of partograph utilization and associated factors among obstetric care givers at public health institutions in central zone, Tigray, Ethiopia.

OBJECTIVES: Partograph is one of the best effective obstetric tools used to monitoring labor and prevent prolonged or obstructed labor which accounts for about 22% of maternal deaths in Ethiopia. This study was aimed to assess partograph utilization and associated factors among obstetric care givers. Facility based cross sectional study was used in the randomly selected health facilities. Total 220 obstetric care givers were selected using simple random sampling technique. Data were entered and analyzed using SPSS version 22.0. Bivariate and multivariate logistic regression analysis was used to identify the associations of each explanatory variable with the outcome variable. Finally, odds ratio with its 95% confidence interval and p-value of 0.05 was used to identify significant variables. RESULT: Out of 198 obstetric care providers, 73.3% used partograph to monitor progress of labor. Those who were diploma holders (AOR = 3.8, CI = 2.2-6.2), receiving basic emergency obstetrics and new born care training (AOR = 5.6, CI 1.1-28.5), age between 20 and 29 years-old (AOR = 0.1, CI = 0.01-0.50), and male health care providers (AOR = 0.37, CI = 0.44-0.95) were factors significantly associated with partograph utilization. Partograph utilization in this study was below the WHO recommendation. Especial emphasizes and interventions should be given to increase partograph utilization.

Factors associated with uptake of post-abortion family planning in Shire town, Tigray, Ethiopia.

OBJECTIVES: Post-abortion contraceptive service is pivotal for the prevention of unwanted pregnancy and alleviation of its complication. Worldwide half of the pregnancy is unplanned, whereas unwanted pregnancy ends up with abortion. This study assessed post-abortion contraceptive uptake and associated factors among abortion service users at health institution in Shire town, North Ethiopia. Institutional based cross-sectional study was conducted from December 15/2016 to March 15, 2017, in Shire town. Data were collected using systematic random sampling technique. Bivariate and multivariable analyses were done to determine the association of each independent variable with the dependent variable. RESULTS: Overall post-abortion contraceptive utilization in this study was 61.5%. Married [AOR 2.59, 95% CI (1.16, 5.65)], completed College education [AOR 5.69, 95% CI (1.61, 20.11)], previous contraceptive used [AOR 3.62, 95% CI (1.77, 7.40)], counseling of family planning [AOR 3.53 95% CI (1.69, 7.37)], grand multipara [AOR 7.91, 95% CI (1.66, 37.74)] and public health institution [AOR 5.95, 95% CI (3.03, 11.72)] were significantly associated with the post-abortion contraceptive utilization. In this study, post-abortion contraceptive utilization was about two-third. Being married, had been completing a college education, had been receiving family planning counseling, previous contraceptive usage, abortion care service at public health institution, and being grand multiparty were determinants of post-abortion contraceptive utilization.

Determinants of teenage pregnancy in Degua Tembien District, Tigray, Northern Ethiopia: A community-based case-control study.

BACKGROUND: Approximately 16 million teenagers aged 15-19 years and 2 million teenagers under the age of 15 years give birth annually, with 95% of these births occurring in developing countries. Ethiopia has one of the highest teenage fertility rates in Sub-Saharan Africa; however determinants of teenage pregnancy are not well studied. Therefore, this study aimed to identify determinants of teenage pregnancy among female teenagers in Degua Tembien district, Tigray, Northern Ethiopia, in 2015. METHODS: A community-based case-control study was conducted in Degua' Tembien district from February 01, 2015 to March 15, 2015 with a randomly selected total sample size of 414 females (with a ratio of 1:2 case to control, 138 and 276 respectively). Data were entered in to Epi-Info and analyzed using SPSS software. Multivariable logistic regression was used to assess predictors of the outcome variable; variables with a p-value <0.25 in bivariable analysis were included in the model. Statistically significance was considered at a p-value ≤0.05 in both bivariable and multivariable logistic regression analyses. RESULT: The mean ages (plus or minus standard deviation (±SD)) of cases and controls were 18.47 (0.72) and 17.09 (1.2) years, respectively. After adjustment for other variables, predictors of teenage pregnancy included: lower monthly income below ~$25 and ~$25-50 (adjusted odds ratio (AOR) = 23.96; 95% confidence interval (95%CI) 4.89-117.29 and AOR = 4.91; 95%CI 1.64-14.66, respectively); aged 18-19 years (AOR = 16.75; 95%CI 6.45-43.47); being married (AOR = 15.91; 95%CI 7.43-34.04); not communicating with parents on reproductive health issues (AOR = 6.52; 95%CI 3.12-13.64) and having a history of maternal teenage pregnancy (AOR = 4.14; 95%CI 1.84-9.33). CONCLUSION: The factors associated with teenage pregnancy in our study were lower family monthly income, being married, being in the 18-19 year age group, not communicating with parents on reproductive health issues and having a maternal history of teenage pregnancy. Programs that encourage parent-teenage communication of reproductive health issues, starting from early adolescence, in order to build skills to prevent pregnancy in the late teenage years, are very important. In addition, multi-pronged activities across sectors that encourage delayed marriage and improve health service utilizations for girls are essential.

Timing of first focused antenatal care booking and associated factors among pregnant mothers who attend antenatal care in Central Zone, Tigray, Ethiopia.

OBJECTIVE: Focused antenatal care became the recommended type of antenatal care following the publication of a World Health Organization trial on antenatal care where it was discovered that the traditional antenatal care approach do not necessarily improve pregnancy out-come. This study was aimed to assess timing of first focused antenatal care booking and associated factors among pregnant mothers. Facility based cross sectional study was used in the randomly selected health facilities. Total 239 pregnant women who visited antenatal clinic were selected using simple random sampling technique and data were entered and analyzed using SPSS version 20.0 software. RESULTS: The study shows that only 41% of pregnant mothers booked timely antenatal care and the median duration of pregnancy at the first visit was 5 months. Multivariate logistic regression analysis showed that gravidity and information received on correct time of antenatal care booking from health care provider were significantly associated with timely initiation of antenatal care. Late antenatal care booking remains high in the study area and this indicated that provide information, education and communication to create community awareness is remarkable and implementing community based discussion up to the local level will be crucial.