Reaction-Diffusion Modeling ERK- and STAT-Interaction Dynamics

<p/> <p>The modeling of the dynamics of interaction between ERK and STAT signaling pathways in the cell needs to establish the biochemical diagram of the corresponding proteins interactions as well as the corresponding reaction-diffusion scheme. Starting from the verbal description available in the literature of the cross talk between the two pathways, a simple diagram of interaction between ERK and STAT5a proteins is chosen to write corresponding kinetic equations. The dynamics of interaction is modeled in a form of two-dimensional nonlinear dynamical system for ERK&#8212;and STAT5a &#8212;protein concentrations. Then the spatial modeling of the interaction is accomplished by introducing an appropriate diffusion-reaction scheme. The obtained system of partial differential equations is analyzed and it is argued that the possibility of Turing bifurcation is presented by loss of stability of the homogeneous steady state and forms dissipative structures in the ERK and STAT interaction process. In these terms, a possible scaffolding effect in the protein interaction is related to the process of stabilization and destabilization of the dissipative structures (pattern formation) inherent to the model of ERK and STAT cross talk.</p

Study of the changes in respiratory function in self-contained underwater breathing apparatus divers

Background: The objective was to investigate the respiratory function of professional divers by conducting spirometry and to compare the data obtained with those of non-divers. Materials and methods: This study involved 52 military divers who carried out dives at small and medium depths using a self-contained underwater breathing apparatus (SCUBA) with open-circuit regulators attached to a mouthpiece. The control group consisted of 48 persons from deck commands with similar physiological characteristics and lifestyle that were not divers and had never been under increased pressure.  Results: It was found that, compared with non-divers, the spirometry parameters of the divers are charac- terised by higher values of forced vital capacity (FVC) of the lungs (p = 0.02), but significantly lower values of the mid-expiratory flow (MEF) parameters: MEF25 (p = 0.06), MEF50 (p = 0.04), and MEF75 (p = 0.01), as well as for the ratio of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FEV1/FVC; p = 0.001) and MEF25–75/FVC ratio (p &lt; 0.001).  Conclusions: Hyperoxia, gas decompression bubbles, hypothermia, mouth-breathing dry, cold, compressed air, and other factors accompanying the diving activity are capable of initiating damage to the airways, which is reflected in characteristic changes in spirometry. The pattern of these changes is consistent with small airway obstruction and they could be related mostly to diving activities.

Qualitative Modelling of Quasi-homogeneous Effects in ERK and STAT Interaction Dynamics

On the basis of qualitative analysis of author's model published in previous paper, the stability and temporal behaviour of quasi-homogeneous distributions of ERK-protein concentrations are analyzed in terms of corresponding reaction-diffusion problem. The stable quasi-homogeneous distributions are treated as a dynamical basis of pathway compartmentalization. It is also shown, that a crowding effect exists in the form of loss of pathway stability. An experimentally verifiable issue for possible existence of protein scaffolding mechanism is derived on the basis of its qualitative correspondence with the pattern formation and molecular crowding effects inherent to the considered model. Moreover, it is demonstrated, that the predicted ERK and STAT pathway instability can be interpreted as traveling wave propagation of molecular concentration drop and jump from the nucleus membrane to the cell one and vice versa

Eustachian tube function test as a predictor of middle ear barotrauma

Background: Most of the cases of middle ear barotrauma in divers are due to the impassability of the Eustachian tube. The aim of our study is to compare the results of tympanometry and Valsalva part of Eustachian Tube Function test (ЕТF-test) with the ability of divers to compensate for the change in ambient pressure in a hyperbaric chamber. Material and methods: The study included 35 professional divers undergoing annual medical examination. For all subjects is measured first intratympanal pressure at rest, then after the maneuver of Valsalva with impedancemeter. Then a barofunction test (BFT) was performed to assess the diving fitness and the passability of the Eustachian tubes. It consists of divers compressing and decompressing in a hyperbaric chamber to a pressure of 2.2 ATA for 1 minute. Based on results from previous studies we are using a 20 DaPa cutoff point on the ETF test to predict Eustachian tube passability and a successful barofunction test. Results: In the current study 24 divers have ETF test results higher than 20 DaPa. 3 divers have ETF test values lower than 20 DaPa in both ears, but none of them displayed difficulties in the BFT. 8 divers have ETF values lower than 20 DaPa in one ear and higher than 20 DaPa in the other. 7 of the last group displayed difficulties with the BFT in the ear with poor ETF result. Conclusions: We consider that the ETF test can be used to assess diving fitness as a screening method before performing a BFT, as values above 20 DaPa guarantee Eustachian tube function sufficient for diving activities. Values of 20 DaPa and less are not a definite predictor of the BFT results. The results of the ETF test can also be used in the usual work of an otorhinolaryngologist to evaluate Eustachian function in cases of unilateral disease of middle ear

Towards High Performance Robotic Actuation

The main objective of this thesis is to enable development of high performance actuation for legged, limbed and mobile robots. Due to the fact that such robots need to support their own weight, their actuators need to be light weight, compact and efficient. Furthermore, a dynamics analysis, shows that the actuators' design may have significant impact on a robot's dynamics sensitivity. These consideration motivate improvements in all actuator design aspects. First, the application-specific design of outer rotor motors with concentrated windings is considered. It is shown that an intrinsic design trade-off exists between a motor's copper loss, core loss and mass, which allows development of motors with superior performance for a particular application. The three main application categories of interest are: electric vehicles, drones and robotic joints. Due to their outstanding torque density, high pole count outer rotor motors are analysed in terms of their design and optimization for robotic applications. Motor design scaling modes are also described in order to outline the main challenges in the implementation of high torque motors. Next, the design of gearboxes for robotic actuation is discussed. A novel type of high reduction Bearingless Planetary Gearbox is introduced which allows large range of reduction ratios to be achieved in a compound planetary stage. In this concept, all gear components float in an unconstrained manner as the planet carrier is substituted with a secondary sun gear. The advantages of the Bearingless Planetary Gearbox over current approaches in terms of improved robustness, load distribution, manufacturability, and assembly are outlined. Finally, analysis, design, and prototyping of rotary planar springs for rotary series elastic actuators is described. A mathematical model, based on curved beam theory, that allows rapid design, analysis, and comparison of rotary springs is developed. Mass reduction techniques based on composite arm structures are introduced and internal arm contact modeling is presented. Motivated by strain energy density analysis, an optimization based spring design approach is developed that allows significant increase in the torque and torque density.</p

Dynamics of bound states of dihydrogen at Cu(I) and Cu(II) species coordinated near one and two zeolite framework aluminium atoms: A combined sorption, INS, IR and DFT study

Abstract Ambient conditions sorption isotherms of dihydrogen in a series of various levels of Cu-exchanged ZSM-5 zeolites, with two different Si/Al ratios, namely 11.5 and 25, show the presence of different amount of Cu centres able to strongly bind H2. Although the isosteric heats of adsorption derived from these isotherms are rather similar, of the order of 30 kJ/mol H2, Inelastic Neutron Scattering (INS) of adsorbed dihydrogen and Fourier-Transformed Infra-Red (FTIR) spectroscopy measurements of adsorbed CO and NO reveal that copper is encountered in two oxidation states. At least two types of Cu(I) ions are clearly detected as well as some heterogeneity of the Cu(II) species. The number of these Cu species is different in the two investigated ZSM-5 materials and depends on the Cu exchange level. With the aid of DFT model cluster calculations we find that under different coordination environments, determined by the Al distribution, both mono- and divalent Cu ions could bind H2 with a different strength. Unprecedentedly, we found that Cu-ions compensating two Al atoms, i.e. formally Cu(II) species, relatively far apart from each other, may behave very similarly to the monovalent Cu-species or alternatively viewed – as Cu(I) species that compensate for two framework Al-atoms. Such Cu-species also form stable η2 dihydrogen complexes

Вентрикуларна фибрилација по ендоскопска ретроградна холангиопанкреатографија кај пациент со вграден уред за лево вентрикуларна асистенција – приказ на случај

Congestive heart failure is a growing global health problem. Left ventricular assist device (LVAD) is a method used to extend the life of patients with congestive heart failure as a definitive treatment or to “bypass” the period until heart transplantation. Ventricular arrhythmias in patients with LVAD are not uncommon. The aim of this paper is to present the case of a patient with an already implanted LVAD and the need for appropriate interdisciplinary medical treatment. Case report: We present the case of a 54-year old patient, A. D., with implanted LVAD - HeartMate 3 due to severe congestive heart failure. The patient was admitted with jaundice at the PHIU Clinic for Gastroenterohepatology with performed endoscopic retrograde cholangiopancreatography (ERCP)) procedure and a stent was placed in the choledochus duct. Immeasurable blood pressure and pulse were recorded in this patient. The ECG was approaching VF (ventricular fibrillation) and it was all asymptomatic by the patient.&nbsp; LVAD mechanical pump leads to continuous blood flow, which means that patients with LVAD not infrequently have no pulse or measurable blood pressure. Also, in patients with LVAD, ECG pulses are with electrical disturbances. VF and ventricular tachycardia (VT) are ventricular arrhythmias that are often seen on ECG in patients with implanted LVAD. Usually these arrhythmias occur with unknown duration and terminate spontaneously. Conclusion: Patients with LVAD are prone to cardiac arrhythmias. The continuous development of medical devices leads to a continuous educational and clinical approach to patients.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Конгестивната срцева слабост е растечки глобален здравствен проблем. Уредот за лево вентрикуларна асистенција (LVAD) се користи за продолжување на животот на пациентите со конгестивна срцева слабост како дефинитивен третман или за премостување на периодот до трансплантација на срце. Вентрикуларните аритмии кај пациентите со LVAD не се невообичаени. Целта на овој труд е да се прикаже случајот на пациент со веќе вграден LVAD и потребата од соодветен интердисциплинарен медицински третман. Приказ на случај: Ви претставуваме случај на 54-годишен пациент, А. Д., со вграден LVAD - HeartMate 3 поради тешка конгестивна срцева слабост. Пациентот е примен со иктерус на ЈЗУ Клиниката за гастроентерохепатологија по што е извршена ендоскопска ретроградна холангиопанкреатографија (ERCP)) и е поставен стент во холедохусниот канал. Кај овој пациент е регистрирано немерлив крвен притисок и пулс. На ЕКГ е регистрирана VF вентрикуларна фибрилација (VF) и сето тоа беше асимптоматски од страна на пациентот. Механичката пумпа на LVAD води до континуиран проток на крв, што значи дека пациентите со LVAD не ретко немаат пулс или мерлив крвен притисок. Исто така, кај пациентите со LVAD, ЕКГ импулсите се со електрични нарушувања. VF и вентрикуларна тахикардија (VT) се вентрикуларни аритмии кои често се гледаат на ЕКГ кај пациентите со имплантиран LVAD. Најчесто овие аритмии се јавуваат со непознато времетраење и спонтано завршуваат. Заклучок: Пациентите со ЛВАД се склони кон срцеви аритмии. Континуираниот развој на медицинските помагала води кон континуиран едукативен и клинички пристап во третманот на пациентите

Laser-Based Techniques for Combustion Diagnostics

Two-photon-induced Degenerate Four-Wave Mixing, DFWM, was applied for the first time to the detection of CO, and NH3 molecules. Measurements were performed in a cell, and in atmospheric-pressure flames. In the cell measurements, the signal dependence on the pressure and on the laser beam intensity was studied. The possibility of simultaneous detection of NH3 and OH was investigated. Carbon monoxide and ammonia were also detected employing two-photon-induced Polarization Spectroscopy, PS. In the measurements performed in a cold gas flow, the signal strength dependence on the laser intensity, and on the polarization of the pump beam, was investigated. In the case of CO, the signal dependence on the number density of CO in the presence of He and N2, was studied. In stable-flame investigations, one dimensional images of the studied species, collected at different heights above the burner, were combined in order to produce two dimensional maps of the species distributions in the flame. Signals from one-, and two-photon polarisation spectroscopy from OH and NH3, were detected simultaneously. The spectrum of the CO molecule was measured at different temperatures. An approach to improve the spatial resolution of the Amplified Stimulated Emission, ASE, was developed. In this approach, two laser beams at different frequencies were crossed in the sample. If the sum of the frequencies of the two laser beams matches a two-photon resonance of the investigated species, only the molecules in the intersection volume will be excited. NH3 molecules and C atoms were studied. The potential of using two-photon LIF for two-dimensional imaging of combustion species was investigated. Applying this technique, NH3, CO, and H, and O atoms were detected spatially resolved. In the case of CO imaging, efforts were made to separate the CO emission from the emission originating from unresonantly excited C2. Detection limits for some of the species are discussed. Although LIF is species specific, several species can be detected simultaneously by utilizing spectral coincidences. Combining one-, and two-photon process, OH, NO, and O were detected simultaneously, as well as OH, NO, and NH3. The temperature dependencies of the involved transitions are discussed. Collisional quenching is the major source of uncertainty in quantitative applications of LIF. A technique for two-dimensional, absolute species concentration measurements, circumventing the problems associated with collisional quenching, was developed. By applying simple mathematics to the ratio of two LIF signals generated from two counterpropagating laser beams, the absolute species concentration could be obtained

Identifying generalized Fitzhugh-Nagumo equation from a numerical solution of Hodgkin-Huxley model

An analytic time series in the form of numerical solution (in an appropriate finite time interval) of the Hodgkin-Huxley current clamped (HHCC) system of four differential equations, well known in the neurophysiology as an exact empirical model of excitation of a giant axon of Loligo, is presented. Then we search for a second-order differential equation of generalized Fitzhugh-Nagumo (GFN) type, having as a solution the given single component (action potential) of the numerical solution. The given time series is used as a basis for reconstructing orders, powers, and coefficients of the polynomial right-hand sides of GFN equation approximately governing the process of action potential. For this purpose, a new geometrical method for determining phase space dimension of the unknown dynamical system (GFN equation) and a specific modification of least squares method for identifying unknown coefficients are developed and applied