Examination of cardio-respiratory coupling preservation and its predictive role in response to resynchronization therapy in patients with heart failure

njihove promene izazvane resinhronizacionom terapijom kod bolesnika sa srčanom slabošću (SS) i redukovanom ejekcionom frakcijom leve komore (EFLK). Metode: U istraživanje su uključeni bolesnici sa dilatativnom kardiomiopatijom i indikacijom za resinhronizacionu terapiju srčane slabosti (CRT) i/ili ugradnju implantabilnog kardioverter defibrilatora. Ispitanici su tokom istraživanja bili deljeni u podgrupe u odnosu na karakteristike srčanog ritma, a poređenje je vršeno sa grupom zdravih kontrola. Srčani i respiratorni signali su simultano beleženi tokom 20 minuta, i ispitivani različitim linerarnim i nelinearnim metodama analize vremenskih serija. Kod ispitanika kojima je ugrađen CRT, snimanje signala je ponovljeno nakon godinu dana i analiza promene parametara autonomne funkcije je odvojeno rađena u grupi CRT „rispondera“ i „nerispondera“. Rezultati: U istraživanje je uključeno 156 ispitanika. Kod bolesnika sa SS redukovana je respiratorna sinusna aritmija, kao i bidirekciona interakcija srčanog i respiratornog signala. Bolesnici iz HF-VES grupe su imali najregularniji srčani ritam i najveću sinhronizaciju rada srca i disanja. Identifikovali smo odnos kratkodometnog, α1(RR), i dugodometnog, α2(RR), skalirajućeg eksponenta vremenskog niza RR intervala kao parametar na osnovu kojeg je moguće grupisanje bolesnika sa SS nezavisno od do sada korišćenih karakterisitka bolesnika. Parametar koji je preoperativno odvojio buduće CRT „rispondere“ od „nerispondera“ bio je α2(RR). Tokom praćenja, kompleksnost srčanog i respiratornog ritma je rasla kod CRT „rispondera“, kao i α1(RR) koji je na kontrolnom snimanju imao značajno više vrednosti u odnosu na „nerispondere“. Na kontroli se beleži porast respiratornih skalirajućih eksponenata kod svih bolesnika, sa izuzetkom α1(Resp) kod CRT „nerispondera“. Tokom praćenja, kardiopulmonalna sinhronizacija je bila očuvana kod CRT „rispondera“. Zaključak: kardio-respiratorne interakcije su narušene kod bolesnika sa SS i redukovanom EFLK, i zavise od prisustva komorskih odnosno pretkomorskih aritmija. Uspeh resinhronizacione terapije je značajno povezan sa njihovom stabilnošćuAim: Examine cardio-respiratory interactions, cardiac and respiratory rhythm, and their changes caused by cardiac resynchronization therapy (CRT) in patients with heart failure (HF) and reduced left ventricular ejection fraction (LVEF). Methods: We included patients with dilated cardiomyopathy and an indication for CRT and/or implantable cardioverter defibrillator implantation. During the study, patients were divided into subgroups according to heart rhythm characteristics, and compared with a group of healthy controls. Cardiac and respiratory signals were simultaneously recorded during 20 minutes, and examined by different linear and nonlinear methods of time series analysis. In subjects with implanted CRT, signal recording was repeated after one year, and the analysis of changes in autonomic function parameters was performed separately in the group of CRT responders and non-responders. Results: We included 156 patients. In HF patients, respiratory sinus arrhythmia and bidirectional causal interactions between the respiratory and cardiac signals were reduced. Patients from the HF-VES group had the most regular heart rhythm and the greatest synchronization of cardiac and respiratory function. We identified the ratio of short-term, α1(RR), and long-term, α2(RR), scaling exponent of RR interval series as a parameter capable to differentiate HF patients regardless of previously used patient characteristics. The parameter that preoperatively separated future CRT "responders" from "non-responders" was α2(RR). During follow-up, the complexity of cardiac and respiratory rhythm increased in CRT responders, as well as α1(RR), which had significantly higher values at the control recording compared to non-responders. Control measurements showed an increase in respiratory scaling exponents in all patients, with the exception of α1(Resp) in CRT non-responders. During follow-up, cardiopulmonary synchronization was preserved in CRT responders. Conclusion: Cardio-respiratory coupling is altered in HF patients with reduced LVEF and depends on the presence of atrial and ventricular arrhythmias. CRT success is related to cardio-respiratory coupling stability

Free planar vibration of structures composed of rigid bodies and elastic beam segments

Ovaj rad predstavlja analizu slobodnih vibracija struktura sastavljenih od krutih tela međusobno spojenih sa elastičnim gredama. Pretpostavlja se da se centri masa krutih tela ne nalaze na neutralnoj osi nedeformisanog elastičnog grednog segmenta kao i da kruta tela vrše ravno kretanje u istoj ravni i da se njihovi centri masa nalaze u toj istoj ravni. Za određivanje frekvencija sistema, modifikacija klasične 'CTMM' metode je upotrebljena. Elastični gredni segmenti se tretiraju kao Ojler-Bernulijeve grede. Prikazan je numerički primer.This article presents free vibration analysis of structures composed of rigid bodies connected with elastic beam segments. It is assumed that the mass centers of rigid bodies are not located on the neutral axes of undeformed elastic beam segments as well as rigid bodies perform planar motion in the same plane and their mass centers are located in that plane. For determination of natural frequencies of the system, modification of the conventional continuous-mass transfer matrix method has been performed. The elastic beam segments are treated as Euler-Bernoulli beams. Numerical example is presented

Noncommutative Electrodynamics from SO(2,3)⋆SO(2,3)_\star Model of Noncommutative Gravity

In our previous work we have constructed a model of noncommutative (NC) gravity based on $SO(2,3)_\star$ gauge symmetry. In this paper we extend the model by adding matter fields: fermions and a $U(1)$ gauge field. Using the enveloping algebra approach and the Seiberg-Witten map we construct actions for these matter fields and expand the actions up to first order in the noncommutativity (deformation) parameter. Unlike in the case of pure NC gravity, first non-vanishing NC corrections are linear in the noncommutativity parameter. In the flat space-time limit we obtain a non-standard NC Electrodynamics. Finally, we discuss effects of noncommutativity on relativistic Landau levels of an electron in a constant background magnetic field and in addition we calculate the induced NC magnetic dipole moment of the electron.Comment: 21 pages, no figure

Nelinearna statička metoda postupnog guranja - pushover analiza AB okvira sa zidanom ispunom

U radu je ukratko opisana problematika proračuna AB okvira sa zidanom ispunom primenom nelinearne statičke metode(pushover analiza). Prikazani su različiti načini modeliranja zidane ispune. Izvršena je pushover analiza AB okvira (P+5) sa zidanom ispunom. Prvo je izvršeno dimenzionisanje AB okvira prema Evrokodu. Nakon toga je sprovedena pushover analiza AB okvira primenom programskog paketa SAP2000. Razmatran je model AB okvira bez ispune i model gde je ispuna modelirana pomoću zamenjujućih dijagonala. Na kraju je data uporedna analiza rezultata iz ova dva modela.In this paper, procedures used for static nonlinear analysis (pushover analysis) of RC frames with masonry infill are presented. Also, different ways how to model masonry infill are described. On the example of RC frames with five stories, the application of pushover analysis is presented. As a first step, RC frame is designed according to Eurocodes. After that, pushover analysis is conducted using somputer program SAP2000. Two computer models are considered. One of RC frame without masonry infill, and other where masonry infill is modeled using diagonal struts. As conclusion, a comparative study of results obtained from previosly described computer models of RC frame is given

Investigation of intersubband transitions in wide bandgap oxide quantum well structures for optoelectronic device applications

There has been a surge of interest in recent years for the advancement of wide bandgap oxides such as zinc oxide (ZnO), magnesium oxide (MgO), gallium oxide (Ga2O3), etc. [1,2]. These materials have gained significant attention due to their distinctive characteristics and properties which are promising for the development of high-performance optoelectronic devices for applications in the domains of sensing, communications, and imaging. More specifically, Ga2O3 has wide bandgap energy of approximately 4.8 to 4.9 electron volts (eV), thus exhibiting exceptional transparency to ultraviolet (UV) radiation while displaying opaqueness to visible light [3]. On a parallel note, ZnO shows exemplary optical and electrical properties, including a high exciton binding energy and substantial oscillator strength [4]. Of particular significance is the exploration of intersubband transitions within multiple quantum well (MQW) structures, which offers a promising path for efficient light absorption and emission in the mid-infrared to terahertz spectral range. In this contribution we will numerically simulate the absorption spectra of the wide bandgap oxide MQW structures, adapting the approach for treating the light-matter interaction suitable when the depolarization field is the dominant many-body contribution, and discuss the potential applications in optoelectronic devices, specifically mid-infrared detectors, quantum cascade lasers, and modulators.IX International School and Conference on Photonics : PHOTONICA2023 : book of abstracts; August 28 - September 1, 2023; Belgrad

Modeling of intersubband transitions in ZnO/ZnMgO Coupled QuantumWells

In recent years ZnO has become a popular semiconductor withmany potential applications in infra-red and THz optical devices owing to awide direct bandgap (3.4 eV) in combination with relatively high exciton binding energy (60 meV) [1]-[2]. In this work, we model the electronic structure of coupled oxide-semiconductor quantum wells by numerically solving the system of coupled Schrödinger-Poisson equations self-consistently (Fig. 1).We compare the obtained results with the recent experimental data[3] and analyze howthe variation of the layers’thicknesses affects the energy states. In addition, we examine the influence of doping to assess the differences between single well and two wells’cases, for the purpose ofdesigning more complex multi-well optical system in the future.VIII International School and Conference on Photonics & HEMMAGINERO workshop : program and the book of abstracts; August 23-27, 2019; Belgrad

Numerical modeling of new oxide-based heterostructures for use in QCL devices

Semiconductor devices operating in the terahertz (THz) and near/mid infrared (IR) parts of the optical spectrum have been continuously explored and improved during the previous two decades [1-3]. Multiple new material platforms are being experimentally and theoretically investigated as candidates for room temperature operation of THz devices. One of the materials under recent consideration is ZnO due to its wide direct bandgap and high exciton binding energy. In this contribution we illustrate the use of a modified version of the Newton-Raphson method to numerically and self-consistently solve a system of SchrödingerPoisson equations for a structure consisting of coupled ZnObased quantum wells. The results obtained are compared with the experimental data available in the literature, after which the Additionally, the impact of the external electric field applied to the structure is assessed in order to determine the doping profile and well/barrier thicknesses that would be most promising for quantum cascade laser applications. Finally, we evaluate the absorption due to intersubband transitions between the bound states.XV Photonics Workshop : book of abstracts; March 13-16, 2022; Kopaoni

CARVEDILOL POPULATION PHARMACOKINETIC ANALYSIS – APPLIED VALIDATION PROCEDURE

Carvedilol is a nonselective beta blocker/alpha-1 blocker, which is used for treatment of essential hypertension, chronic stable angina, unstable angina and ischemic left ventricular dysfunction. The aim of this study was to describe carvedilol population pharmacokinetic (PK) analysis as well as the validation of analytical procedure, which is an important step regarding this approach. In contemporary clinical practice, population PK analysis is often more important than standard PK approach in setting a mathematical model that describes the PK parameters. Also, it includes the variables that have particular importance in the drugs pharmacokinetics such as sex, body mass, dosage, pharmaceutical form, pathophysiological state, disease associated with the organism or the presence of a specific polymorphism in the isoenzyme important for biotransformation of the drug. One of the most frequently used approach in population PK analysis is the Nonlinear Modeling of Mixed Effects - NONMEM modeling. Analytical methods used in the data collection period is of great importance for the implementation of a population PK analysis of carvedilol in order to obtain reliable data that can be useful in clinical practice. High performance liquid chromatography (HPLC) analysis of carvedilol is used to confirm the identity of a drug and provide quantitative results and also to monitor the efficacy of the therapy. Analytical procedures used in other studies could not be fully implemented in our research as it was necessary to perform certain modification and validation of the method with the aim of using the obtained results for the purpose of a population pharmacokinetic analysis. Validation process is a logical terminal phase of analytical procedure development that provides applicability of the procedure itself. The goal of validation is to ensure consistency of the method and accuracy of results or to confirm the selection of analytical method for a given sample and drug. This study confirmed the importance of using valid analytical procedure for the purpose of carvedilol population pharmacokinetic analysis. Identification of demographic, pathophysiological and other factors that may influence the population carvedilol PK parameters gives the physician the possibility of a more comprehensive overview of the patient and better optimization of the therapeutical regimen

Environmental and Community Stability of a Mountain Destination: An Analysis of Residents’ Perception

This study aims to explore the use of the social-ecological system (SES) in tourism of a mountain area. Authors examined residents’ perceptions of tourism impacts on four SES aspects: ecosystems, local knowledge, people and technology and property rights institutions. The aim is to find area that will be a “common ground” for community and area that can be a source of conflict and will require additional work to solve the differences. Second objective was to examine residents’ perception towards future local development tourism policies (winter tourism, seasonality and environment and culture) and how those policies can affect natural, socio-economic and cultural aspects of mountain area. Residents’ perceptions of sustainable tourism development potential, perceivedtourismimpacts,analysisofcommunityattachmentandemploymentsectorofstakeholder were involved in this study. The authors applied the Q-methodology, as one SES-allied approach, in a small mountain community of Kopaonik, the Republic of Serbia. The results revealed that residents’ agreement/disagreement is connected with two aspects: ecosystem and property rights andthatecosystemcanbesignificantlyinfluencedbyallthreedevelopmentpolicies. Findingssuggest that development of future natural conservation plans and new cultural attractions can have positive effects on all parts of social-ecological system. Some practical implications of those findings for tourism planning and development are also discussed