Bistatic noise radar: Demonstration of correlation noise suppression

In this study, spatial separation of the radar transmitter and receiver units is considered, as a means of reducing the masking effect in noise radars. A bistatic radar system is constructed, with emphasis on a lightweight transmitter unit that can be mounted on a commercial Unmanned Aerial Vehicle (UAV). The system uses pseudo-random noise, generated digitally at the receiver and transmitter units. Correlation losses, due to non-linearities in the transmitter and receiver units, are measured to 0.1\ua0dB. This study shows that by separating the transmitter and receiver unit the masking effect is significantly reduced, compared to a monostatic setup. This reduction is enough for the system to detect a slow flying UAV. Thus, bistatic separation should be considered as a practical tool to reduce the masking effect. By processing clutter with an extended CLEAN algorithm, the correlation noise floor is further suppressed

Implementation of a coherent real-time noise radar system

The utilisation of continuous random waveforms for radar, that is, noise radar, has been extensively studied as a candidate for low probability of intercept operation. However, compared with the more traditional pulse-Doppler radar, noise radar systems are significantly more complicated to implement, which is likely why few systems exist. If noise radar systems are to see the light of day, system design, implementation, limitations etc., must be investigated. Therefore, the authors examine and detail the implementation of a real-time noise radar system on a field programmable gate array. The system is capable of operating with 100% duty cycle, 200\ua0MHz bandwidth, and 268\ua0ms integration time while processing a range of about 8.5\ua0km. Additionally, the system can perform real-time moving target compensation to reduce cell migration. System performance is primarily limited by the memory bandwidth of the off-chip dynamic random access memory

Factors Associated with Undiagnosed Obstructuve Sleep Apnea in Hypertensive Primary Care Patients

Objective. In hypertensive primary care patients below 65 years of age, (i) to describe the occurrence of undiagnosed obstructive sleep apnoea (OSA), and (ii) to identify the determinants of moderate/severe OSA. Design. Cross-sectional. Setting. Four primary care health centres in Sweden. Patients. 411 consecutive patients (52% women), mean age 57.9 years (SD 5.9 years), with diagnosed and treated hypertension (BP \u3e140/90). Main outcome measures. Occurrence of OSA as measured by the apnoea hypopnoea index (AHI). Results. Mild (AHI 5–14.9/h) and moderate/severe (AHI \u3e 15/h) OSA were seen among 29% and 30% of the patients, respectively. Comparing those without OSA with those with mild or moderate/severe OSA, no differences were found in blood pressure, pharmacological treatment (anti-hypertensive, anti-depressive, and hypnotics), sleep, insomnia symptoms, daytime sleepiness, or depressive symptoms. Obesity (BMI \u3e 30 kg/m2) was seen in 30% and 68% of the patients with mild and moderate/severe OSA, respectively. Male gender, BMI \u3e 30 kg/m2, snoring, witnessed apnoeas, and sleep duration \u3e8 hours were determinants of obstructive sleep apnoea. Conclusion. Previously undiagnosed OSA is common among patients with hypertension in primary care. Obesity, snoring, witnessed apnoeas, long sleep duration, and male gender were the best predictors of OSA, even in the absence of daytime sleepiness and depressive symptoms

Factors associated with undiagnosed obstructive sleep apnoea in hypertensive primary care patients

Objective. In hypertensive primary care patients below 65 years of age, ( i ) to describe the occurrence of undiagnosed obstructive sleep apnoea ( OSA ), and ( ii ) to identify the determinants of moderate/severe OSA. Design. Cross-sectional. Setting. Four primary care health centres in Sweden. Patients. 411 consecutive patients ( 52% women ), mean age 57.9 years ( SD 5.9 years ), with diagnosed and treated hypertension ( BP >140/90 ). Main outcome measures. Occurrence of OSA as measured by the apnoea hypopnoea index ( AHI ). Results. Mild ( AHI 5–14.9/h ) and moderate/severe ( AHI > 15/h ) OSA were seen among 29% and 30% of the patients, respectively. Comparing those without OSA with those with mild or moderate/severe OSA, no differences were found in blood pressure, pharmacological treatment ( anti-hypertensive, anti-depressive, and hypnotics ), sleep, insomnia symptoms, daytime sleepiness, or depressive symptoms. Obesity ( BMI > 30 kg/m2 ) was seen in 30% and 68% of the patients with mild and moderate/severe OSA, respectively. Male gender, BMI > 30 kg/m2, snoring, witnessed apnoeas, and sleep duration >8 hours were determinants of obstructive sleep apnoea. Conclusion. Previously undiagnosed OSA is common among patients with hypertension in primary care. Obesity, snoring, witnessed apnoeas, long sleep duration, and male gender were the best predictors of OSA, even in the absence of daytime sleepiness and depressive symptoms

Development and psychometric evaluation of the Motivation to Use CPAP Scale (MUC-S) using factorial structure and Rasch analysis among patients with obstructive sleep apnea before CPAP treatment is initiated

Background Continuous positive airway treatment (CPAP) is first-line treatment for obstructive sleep apnea (OSA), but adherence tends to be low. A clinical tool focusing on motivation to use CPAP is missing. The purpose was to develop a brief questionnaire to assess motivation to use CPAP that is psychometrically robust and suitable for use in clinical practice. Methods A convenience sample including 193 treatment naive patients with OSA (67% men; mean age = 59.7 years, SD 11.5) from two CPAP clinics was used. Clinical assessments and full night polygraphy were performed. Questionnaires administered before CPAP treatment included the newly developed Motivation to Use CPAP Scale (MUC-S), Minimal Insomnia Symptoms Scale (MISS), Epworth Sleepiness Scale (ESS), and Attitude towards CPAP treatment Inventory (ACTI). The validity and reliability of the MUC-S were investigated using Rasch and exploratory factor analysis models. Measurement invariance, dimensionality and differential item functioning (i.e., across gender groups, excessive daytime sleepiness (ESS), insomnia (MISS) and attitude towards CPAP (ACTI) groups) were assessed. Results The results supported a two-factor solution (autonomous motivation, 6 items, factor loadings between 0.61 and 0.85 and controlled motivation, 3 items, factor loadings between 0.79 and 0.88) explaining 60% of the total variance. The internal consistency was good with Cronbach’s alpha of 0.88 and 0.86 for the two factors. No differential item functioning was found. A latent class analysis yielded three profiles of patients with high (n = 111), moderate (n = 60) and low (n = 22) motivation. Patients with high motivation were older, had higher daytime sleepiness scores, more insomnia symptoms and a more positive attitude towards CPAP. Conclusions The MUC-S seems to be a valid tool with robust psychometric properties suitable for use at CPAP clinics. Future studies should focus on how motivation changes over time and if MUC-S can predict objective long-term CPAP adherence

Longitudinal Relationships between Nomophobia, Addictive Use of Social Media, and Insomnia in Adolescents

Abstract: (1) Background: Temporal relationships between nomophobia (anxiety related to ‘no mobile phone phobia’), addictive use of social media, and insomnia are understudied. The present study aimed to use a longitudinal design to investigate temporal relationships between nomophobia, addictive use of social media, and insomnia among Iranian adolescents; (2) Methods: A total of 1098 adolescents (600 males; 54.6%; age range = 13 to 19) were recruited from 40 randomly selected classes in Qazvin, Iran. They completed baseline assessments. The same cohort was invited to complete three follow-up assessments one month apart. Among the 1098 adolescents, 812 (400 males; 49.3%; age range = 13 to 18) completed the baseline and three follow-up assessments. In each assessment, the participants completed three questionnaires, including the Nomophobia Questionnaire (NMP-Q), Bergen Social Media Addiction Scale (BSMAS), and Insomnia Severity Index (ISI); (3) Results: Multilevel linear mixed-effects regression analyses showed that participants demonstrated increased insomnia longitudinally over 3 months (B = 0.12 and 0.19; p = 0.003 and <0.001). Insomnia was associated with nomophobia (B = 0.20; p < 0.001) and addictive use of social media (B = 0.49; p < 0.001). Nomophobia and addictive use of social media interacted with time in associations with insomnia as demonstrated by significant interaction terms (B = 0.05; p < 0.001 for nomophobia; B = 0.13; p < 0.001 for addictive use of social media); (4) Conclusions: Both nomophobia and addictive use of social media are potential risk factors for adolescent insomnia. The temporal relationship between the three factors suggests that parents, policymakers, and healthcare providers may target reducing nomophobia and addictive use of social media to improve adolescents’ sleep

Psychometric aspects of obstructive sleep apnea syndrome

Introduction: Obstructive sleep apnea (OSA) is a common chronic disorder consisting of episodes with impaired breathing due to obstruction of the upper airways. Treatment with Continuous Positive Airway Pressure (CPAP) is a potentially effective treatment, but adherence is low. Several potential factors affecting adherence, e.g., subjective sleepiness and personality, are only quantifiable through questionnaires. Better knowledge about psychometric properties of such questionnaires might improve future research on CPAP adherence and thus lead to better treatment options. Aim: Study I: To describe the devlopment and initial testing of the Side Effects of CPAP treatment Inventory (SECI) questionnaire. Study II: To describe the prevalence of Type D personality in OSAS patients with CPAP treatment longer than 6 months and the association with self-reported side effects and adherence. Study III: To study whether any of the items in the Epworth Sleepiness Scale (ESS) exhibit differential item functioning and, if so, to which degree. Study IV: To examine the evolution of CPAP side effects over time; and prospectively assess correlations between early CPAP side effects and treatment adherence. Patients and Methods: In study I, SECI items were based on a literature review, an expert panel and interviews with patients. It was then mailed to 329 CPAP-treated OSAS patients. Based on this, a principal component analysis was performed, and SECI results were compared between adherent and non-adherent patients. In study II, the population consisted of 247 OSAS patients with ongoing CPAP treatment. The DS14 was used to assess the prevalence of type D personality, and SECI and adherence data from medical records were used to correlate Type D personality to side effects and adherence. In study III, the population consisted of pooled data from 1,167 subjects who had completed the ESS in five other studies. Ordinal regression and Rasch analysis were used to assess the existence of differential item functioning for age and gender. The cutoff for age was 65 years in the Rasch analysis. In study IV, SECI was sent to 186 subjects with newly diagnosed OSAS three times during the first year on CPAP. SECI results were followed over time within subjects, and were correlated to treatment dropout during the first year and machine usage time after 6 months. Results: SECI provides a valid and reliable instrument to measure side effects, and non-adherent patients have higher scores (i.e., were more bothered by side effects) than adherent patients (study I). Type D personality was prevalent in approximately 30 % of CPAP treated OSAS patients, and was associated to poorer objective and subjective adherence as well as more side effects (study II). Differential item functioning was present in items 3, 4 and 8 for age in both DIF analyses, and to gender in item 8 the Rasch analysis (study III). Dry mouth and increased number of awakenings were consistently associated to poorer adherence in CPAP treated patients. Side effects both emerged and resolved over time (study IV). Conclusions: Differences in previous research regarding side effects and CPAP adherence might be explained by differences in how side effects and adherence are defined. While some side effects are related to adherence, others are not. Side effects are furthermore not stable over time, and might be related to personality. ESS scores are also related to CPAP adherence according to previous research, but might be affected by other factors than sleepiness, such as age and possibly gender

Psychometric aspects of obstructive sleep apnea syndrome

Introduction: Obstructive sleep apnea (OSA) is a common chronic disorder consisting of episodes with impaired breathing due to obstruction of the upper airways. Treatment with Continuous Positive Airway Pressure (CPAP) is a potentially effective treatment, but adherence is low. Several potential factors affecting adherence, e.g., subjective sleepiness and personality, are only quantifiable through questionnaires. Better knowledge about psychometric properties of such questionnaires might improve future research on CPAP adherence and thus lead to better treatment options. Aim: Study I: To describe the devlopment and initial testing of the Side Effects of CPAP treatment Inventory (SECI) questionnaire. Study II: To describe the prevalence of Type D personality in OSAS patients with CPAP treatment longer than 6 months and the association with self-reported side effects and adherence. Study III: To study whether any of the items in the Epworth Sleepiness Scale (ESS) exhibit differential item functioning and, if so, to which degree. Study IV: To examine the evolution of CPAP side effects over time; and prospectively assess correlations between early CPAP side effects and treatment adherence. Patients and Methods: In study I, SECI items were based on a literature review, an expert panel and interviews with patients. It was then mailed to 329 CPAP-treated OSAS patients. Based on this, a principal component analysis was performed, and SECI results were compared between adherent and non-adherent patients. In study II, the population consisted of 247 OSAS patients with ongoing CPAP treatment. The DS14 was used to assess the prevalence of type D personality, and SECI and adherence data from medical records were used to correlate Type D personality to side effects and adherence. In study III, the population consisted of pooled data from 1,167 subjects who had completed the ESS in five other studies. Ordinal regression and Rasch analysis were used to assess the existence of differential item functioning for age and gender. The cutoff for age was 65 years in the Rasch analysis. In study IV, SECI was sent to 186 subjects with newly diagnosed OSAS three times during the first year on CPAP. SECI results were followed over time within subjects, and were correlated to treatment dropout during the first year and machine usage time after 6 months. Results: SECI provides a valid and reliable instrument to measure side effects, and non-adherent patients have higher scores (i.e., were more bothered by side effects) than adherent patients (study I). Type D personality was prevalent in approximately 30 % of CPAP treated OSAS patients, and was associated to poorer objective and subjective adherence as well as more side effects (study II). Differential item functioning was present in items 3, 4 and 8 for age in both DIF analyses, and to gender in item 8 the Rasch analysis (study III). Dry mouth and increased number of awakenings were consistently associated to poorer adherence in CPAP treated patients. Side effects both emerged and resolved over time (study IV). Conclusions: Differences in previous research regarding side effects and CPAP adherence might be explained by differences in how side effects and adherence are defined. While some side effects are related to adherence, others are not. Side effects are furthermore not stable over time, and might be related to personality. ESS scores are also related to CPAP adherence according to previous research, but might be affected by other factors than sleepiness, such as age and possibly gender

Definitions of events.....................................................................................................................................................7

Papers I and II are reproduced with permission from Wile