This document presents a new complete standalone system for a recognition of sleep apnea using signals from the pressure sensors placed under the mattress. The developed hardware part of the system is tuned to filter and to amplify the signal. Its software part performs more accurate signal filtering and identification of apnea events. The overall achieved accuracy of the recognition of apnea occurrence is 91%, with the average measured recognition delay of about 15 seconds, which confirms the suitability of the proposed method for future employment. The main aim of the presented approach is the support of the healthcare system with the cost-efficient tool for recognition of sleep apnea in the home environment.

The ballistocardiography is a technique that measures the heart rate from the mechanical vibrations of the body due to the heart movement. In this work a novel noninvasive device placed under the mattress of a bed estimates the heart rate using the ballistocardiography. Different algorithms for heart rate estimation have been developed.

Methods based exclusively on heart rate hardly allow to differentiate between physical activity, stress, relaxation, and rest, that is why an additional sensor like activity/movement sensor added for detection and classification. The response of the heart to physical activity, stress, relaxation, and no activity can be very similar. In this study, we can observe the influence of induced stress and analyze which metrics could be considered for its detection. The changes in the Root Mean Square of the Successive Differences provide us with information about physiological changes. A set of measurements collecting the RR intervals was taken. The intervals are used as a parameter to distinguish four different stages. Parameters like skin conductivity or skin temperature were not used because the main aim is to maintain a minimum number of sensors and devices and thereby to increase the wearability in the future.

We propose a framework for designing observers possessing global convergence properties and desired asymptotic behaviors for the state estimation of nonlinear systems. The proposed scheme consists in combining two given continuous-time observers: One, denoted as global, ensures (approximate) convergence of the estimation error for any initial condition ranging in some prescribed set, while the other, denoted as local, guarantees a desired local behavior. We make assumptions on the properties of these two observers, and not on their structures, and then explain how to unite them as a single scheme using hybrid techniques. Two case studies are provided to demonstrate the applicability of the framework. Finally, a numerical example is presented.

We study the design of state observers for nonlinear networked control systems (NCSs) affected by disturbances and measurement noise, via an emulation-like approach. That is, given an observer designed with a specific stability property in the absence of communication constraints, we implement it over a network, and we provide sufficient conditions on the latter to preserve the stability property of the observer. In particular, we provide a bound on the maximum allowable transmission interval (MATI) that guarantees an input-to-state stability (ISS) property for the corresponding estimation error system. The stability analysis is trajectory-based, utilizes small-gain arguments, and exploits a persistently exciting property of the scheduling protocols. This property is key in our analysis and allows us to obtain significantly larger MATI bounds in comparison to the ones found in the literature. Our results hold for a general class of NCSs; however, we show that these results are also applicable to NCSs implemented over a specific physical network called WirelessHART (WH). The latter is mainly characterized by its multihop structure, slotted communication cycles, and the possibility to simultaneously transmit over different frequencies. We show that our results can be further improved by taking into account the intrinsic structure of the WH–NCS model. That is, we explicitly exploit the model structure in our analysis to obtain an even tighter MATI bound that guarantees the same ISS property for the estimation error system. Finally, to illustrate our results, we present analysis and numerical simulations for a class of Lipschitz nonlinear systems and high-gain observers.

Introduction: A Holter blood pressure monitoring is a basic method for the diagnosis and evaluation of hypertension therapy. Hypertension in children and adolescents is defined as an increase of systolic/diastolic pressure, which is equal, or above 95th percentile blood pressure for sex, age, and height. Aim: The aim of this study is to analyze the etiology of arterial hypertension (AH) in the pediatric population. Methods: Research had descriptive and retrospective character. During the period from March 2006 to April 2020, 1527 registered continuous Holters of blood pressure were analyzed. Data were taken from the medical documentation of patients that were hospitalized on Pediatric Clinic (register of continuous Holter of blood pressure). Results: Out of the total number of registered and analyzed patients 833 were male (54.5%) with dominant age 15–19 years of life 774 (50.6%), school-age children 660 (43.2%), preschool children 93 (6.1%). We had 902 (59%) first registrations and 626 (41%) control registrations. AH was verified in 52 patients (387 records of continuous Holter of blood pressure were performed to them). Primary AH was verified in 27 patients and secondary AH in 25 patients. Forty patients (76.9%) were treated with monotherapy while combined therapy was used in 12 (23.1%) of cases. Renal cause was in 28% patients, endocrine in 24%, cardiovascular in 24%, neurological in 16%, and rheumatic in 8% of patients with secondary AH. Conclusion: Continuous Holter of blood pressure represents useful diagnostic method and method of control of high blood pressure in children and adolescents. It should be routine method in everyday pediatric clinical practice especially in pediatric cardiology.

Contemporary wireless networks dramatically enhance data rates and latency to become a key enabler of massive communication among various low-cost devices of limited computational power, standardized by the Long-Term Evolution (LTE) downscaled derivations LTE-M or narrowband Internet of Things (NB IoT), in particular. Specifically, assessment of the physical-layer transmission performance is important for higher-layer protocols determining the extent of the potential error recovery escalation upwards the protocol stack. Thereby, it is needed that the end-points of low processing capacity most efficiently estimate the residual bit error rate (BER) solely determined by the main orthogonal frequency-division multiplexing (OFDM) impairment–carrier frequency offset (CFO), specifically in small cells, where the signal-to-noise ratio is large enough, as well as the OFDM symbol cyclic prefix, preventing inter-symbol interference. However, in contrast to earlier analytical models with computationally demanding estimation of BER from the phase deviation caused by CFO, in this paper, after identifying the optimal sample instant in a power delay profile, we abstract the CFO by equivalent time dispersion (i.e., by additional spreading of the power delay profile that would produce the same BER degradation as the CFO). The proposed BER estimation is verified by means of the industry-standard LTE software simulator.

Long QT syndrome (LQTS) is a rare (1:2500–1:10,000) inherited disorder characterized by the onset of arrhythmogenic syncope, polymorphic ventricular tachycardia, and sudden cardiac death. The aim of this article was to describe an unexpected success with an unusual therapeutic modality of a patient diagnosed with LQTS syndrome (suspected Romano–Ward syndrome) during an 8-year period. A 59-year-old female patient was admitted to the hospital due to chest pain and nausea, and after diagnostic and therapeutical approach, a permanent dual-chamber rate-modulated (DDDR) pacemaker was implanted instead of the implantable cardioverter defibrillator (ICD). During the 8-year period, the patient remained stable, without rhythm disorder. Romano–Ward syndrome as a congenital LQTS carries a high risk of sudden cardiac death and presents an indication for ICD. In this patient, for objective reasons, this could not be performed. Implantation of a DDDR with an appropriate pharmacological therapy, including propranolol, in this case, proved to be a successful therapeutic modality.

Introduction: The head-up tilt table test is noninvasive diagnostic procedure, which is used in the diagnosis of syncope. Syncope presents a benign short-term disorder of cerebral circulation with the sudden loss of consciousness and muscle tone. Aim: The aim is to present not only the role and importance of orthostatic tests in the daily clinical practice of pediatric cardiology, neuropediatrics but also pediatrics in general. Patients and Methods: This study has retrospective descriptive character and included the period from April 1997 to June 2020, during which the registration and analysis of orthostatic stability tests (head-up/tilt table test, tilt table test) was performed. Medical documentation of outpatient and hospitalized patients on the Paediatric Clinic of Clinical Center University of Sarajevo (Register of Tilt Table Test) was used. Results: During this period, 1029 tests were registered and analyzed. Modification test (head-up) was performed in 132 (12.8%) patients, and since 2008, classic tilt table test was performed in 897 (87.1%) patients. Patients were 6.5–19 years old, with a predominance of female patients 611 (59.4%). There were 519 (50.4%) patients who were 15–19 years old and 510 (49.6%) patients who were under 15 years of age. Indications were syncope or suspected syncope in 671 (65.2%) patients, cardiovascular etiology (arrhythmias, chest pain, congenital heart defects [CHDs], surgically corrected CHDs, hypotension, and hypertension) in 195 (19%) patients, neuropediatric pathology (epilepsia, suspected epilepsia, headache, vertigo) in 101 (9.8%) patients, and other indications in 62 (6.03%) patients. From the total number of tests, 862 were first tests (83.4%) and 167 were control tests (16.3%). The positive test was found in 538 (52.3%) patients, most often vasovagal syncope (473 patients or 87.9%). Conclusion: Tilt table test is a reliable diagnostic tool in examining the etiology of syncope, primarily vasovagal, and is an extremely important method primarily in cardiopediatric and neuropediatric daily diagnostics.

Abstract In this investigation, we have synthesized YbxY1-xF3 solid solutions by fluorination of yttrium and ytterbium sesquioxides with ammonium hydrogen difluoride. According to the XRD analysis, all synthesized YbxY1-xF3 samples have an orthorhombic crystal structure belonging to the β-YF3 structural type. The refinement of crystal structure was done by the Rietveld method within the Pnma space group using the TCH pseudo-Voigt function. The anisotropic peak broadening was analyzed, and the average apparent crystallite size is about 50 nm with a small anisotropy of shape, while the significant microstrain that is highly anisotropic is present in all samples. The temperature-dependent magnetic susceptibility was analyzed by applying the model of a free ion perturbed by the crystal field. We have obtained the effective magnetic quantum numbers Mieff of four Kramer's doublets of Yb3+ ion along with the entire crystal field splitting of the 2F7/2 manifold of Yb3+ in YF3. The acquired maximum energy splitting of the ground level is about 150 K in our most diluted samples. The field-dependent isothermal magnetization measurements were carried out at various temperatures and analyzed by classical Langevin function. Results obtained from magnetic measurements show that all YbxY1-xF3 (x ≠ 0) solid solutions exhibit pure paramagnetic behavior in the whole temperature range from 2 to 300 K, with a predominant antiferromagnetic exchange interactions.

Increasing changes in the market have caused companies to turn largely to lowering all unnecessary costs in order to be competitive. Competitiveness is a concept that is being explored progressively. This paper offered a way to measure enterprise competitiveness. Competitiveness testing was conducted on companies in the field of food industry in Bosnia and Herzegovina (B&H). A systematic sample was used. The collected data were analysed by factor analysis. Out of a total of 8 dimensions used, the factor analysis performed a reduction of these dimensions and led to the final 6 dimensions that determine the competitiveness of companies in the field of food industry in B&H. The obtained results showed that these dimensions stand out from others and represent the competitiveness of the company. These dimensions are: cost competition, price competition, product and business process innovation, customer satisfaction, delivery reliability and organisational learning. This research will help managers of companies in the food industry in B&H to improve market competitiveness. The methodology used in this paper will help other companies to improve competitiveness and achieve better results in the market.