Cyber sickness in low-immersive, semi-immersive, and fully immersive virtual reality.

It is known that virtual reality (VR) experience may cause cyber sickness. One aspect of VR is an immersion or otherwise sense of presence, the sense of feeling oneself in a virtual world. In this paper an experiment which was conducted in order to find the link between level of immersion and cyber sickness felt by participants is presented.

Factors controlling the intracellular concentration of calcium and the spontaneous activity of the ureter.

The role of the electrogenic Na(+)-Ca(2+)-exchange mechanism in regulating the spike activity of the ureter was studied. The ureter cells were shown to be capable of generating action potentials (AP) in sodium-free Krebs solution. The time during which the spikes are generated is in exponential dependence on the concentration of calcium ions in the medium, [Ca2+]o within 2.

[K+-dependent enzyme activity of H+-ATPase in the E. coli membrane].

It was shown that DCCD-sensitive ATPase activity of isolated membranes and preparations of F1F0 only from anaerobically grown E. coli depended on K+ activity. F1F0 include two additional proteins which correspond to the Trk system.

[Electrochemical potential difference for H+-ions as a regulator of redox profile of membrane during ATP-dependent ion transport in E. coli].

The importance of delta mu H+ for transport of K+ via K(+)-ionophore and H(+)-K(+)-pump was studied. It was shown that the operation of the pump was decelerated by oxidant ferrycyanide, whereas sulfhydryl reagent dithiothreitol (DTT) drastically accelerated ATP driven ion exchange. Introduction of protonophore CCCP into the medium completely blocked the pump operation.

[Relation between H2 production and energy-dependent metabolism of H+ and K+ ions in E.coli].

Anaerobically grown E. coli escape H2 into the medium during the operation of H(+)-K(+)-pump exchanging 2H+ from a cell for one K+ of the medium. Anaerobic cells grown in the nitrate medium as well as the aerobically grown bacteria possessed neither 2H+/K+ exchange system, nor the ability for H2 production.

[The role of Ca2+ ions in a phage infection of Corynebacterium glutamicum].

It was shown that neither uncouplers of oxidative phosphorylation, nor lack of Ca2+ ions affected the normal MC-2 phage absorption on Corynebacterium glutamicum cells, while the phage development was repressed under these conditions. Simultaneous measurement of Ca2+, K+ and H+ ion flows, as well as measurement of membrane potential showed that the addition of the phage into the experimental medium led to significant depolarization of the membrane from -160 mV to -100 mV due to the penetration of Ca2+ ions into the cells followed by K+ and H+ efflux. The (Ca2+) to (K+ + H+) ratio was shown to be 1 : 1.

[The role of Na+/Ca2+ exchange in the generation of delayed electrical activity of smooth muscle cells].

It was shown that electrogenic 3Na+/Ca2+ antiport evoked depolarization of the membranes and Ca2+ ions influx through Ca2+ activated channels which lead to the appearance of stable self-oscillation of the membrane potential (MP), as well as Na+ and Ca2+ ions intracellular concentrations.

[The role of sodium ions of the medium on the generation of spike activity in the ureter].

In sodium-free Krebs solution ureter cells are able to generate action potentials. Logarithm of time, during which spikes are generated, is in proportion to the concentration of calcium ions in the surrounding medium in interval from 2.5 to 15 mmol/l.

Formation of an ion transport supercomplex in Escherichia coli. An experimental model of direct transduction of energy.

Hydrogen gas production was observed to occur during ATP-driven H+/K+ exchange in anaerobically grown E. coli. Neither process was found in aerobically grown cells or anaerobic cells grown on nitrate medium or when the osmotic pressure was decreased or K+ removed, or finally when DCCD, arsenate or CCCP was applied.

[Regulation of the phases of slow-wave ureteral activity by sodium and calcium ions].

The ionic nature of each of the two slow wave depolarization phases of cat's ureter pacemaker during i.a. perfusion of kidneys, was studied.

[N,N'-dicyclohexylcarbodiimide-sensitive K+-dependent ATPase activity in Escherichia coli].

ATPase activity sensitive to N,N'-dicyclohexylcarbodiimide and dependent on K+ content in medium is observed only in anaerobically grown Escherichia coli and as the analysis of mutants with defects in different subunits of (F0F1) H+-ATPase and in potassium transport shows only under the structural integrity of both F0F1 and K+-ionophore (the Trk system). The obtained results confirm the data on the H+/K+-exchange and indicate that the F0F1 and Trk systems in anaerobically grown bacteria unite into the same membrane supercomplex inside which the direct energy transfer occurs without a mediation of delta-mu H+.

The constitutive K+ pump in Serratia marcescens.

Transport of K+ and H+ in the anaeronically and aerobically grown bacterium Serratia marcescens has been studied. The volumes of one cell of the anaerobically and aerobically grown bacterium were 3.7 X 10(-13) cm3 and 2.

[Characteristics of K+ uptake in S. enteritidis bacteria].

Bacterial Salmonella enteritidis var. Issatchenko in media without exogenic energy source uptakes K+ in one step with Km 2.1 mM and Vmax 0.

[Regulation of spontaneous oscillations in the ureteral membrane potential by using physiologically active compounds].

I. a. perfusion of the Krebs solution of the cat ureter virtually altered characteristics of slow wave activity (SWA) observed with the blood circulation.

[The nature of H+-K+-exchange in anaerobically and aerobically grown S. typhimurium].

H+-K+-exchange via the Trk-like system of K+ accumulation takes place in anaerobically grown S. typhimurium LT-2 with stable ratio of DCC-sensitive ionic fluxes, equal to 2H+ of a cell for one K+ of the medium. This exchange is now observed in the mutant S.

[Interaction of ionic membrane mechanisms in the regulation of slow electrical activity of the smooth muscle cells of the ureter].

The effects of Na-free medium, Na-K pump inhibitors, ATP and Ca++ ion antagonists in calcium channels (verapamil, Mn++) on the slow-wave spontaneous activity of the ureter pace-maker zone were studied under conditions of i. a. perfusion of kidney.

[The character of K+ uptake in anaerobically grown S. typhimurium].

Tre character of K+ uptake in anaerobically grown S. typhimurium LT-2 is studied. In the alkaline media with glucose and moderate K+ activity these bacteria uptake K+ in two steps, the first of which has a high rate of K+ uptake, Km 2.

[Accumulation of K+ in E. coli grown in aerobic conditions].

The character of K+ accumulation in E. coli grown aerobilcally in the salt medium with succinate was studied. K+ uptake via the Trk system has Km 3.

[Interaction of H+ and K+ transport systems in E. coli growing under anaerobic and aerobic conditions].

The interaction of H+-ATPase complex F1 X F0 with the Trk system of K+ accumulation in E. coli grown quasi-anaerobically in pepton media with glucose (anaerobia) and aerobically in the salt medium with succinate (aerobia) treated with cyanide was studied. The ratio of H+ fluxes via F1 X F0 and K+ fluxes via the Trk system is stable and equals 2 in anaerobia and is changed from 0.

[The role of ATPase subunits from E. coli in hydrogen-potassium exchange].

A hypothesis was developed that in membranes of glycolysing bacteria functioned supercomplexes (F1 X F0-TrkA) and (F0-TrkA) which operated as H+-K+-pump exchanging 2H+ for one K+ and as H+-K+-antiport respectively. The mutants with defects in alpha, beta and gamma subunits of ATPase F1 manifested the alteration only in the work of (F1 X F0-TrkA). Defect in epsilon subunit of F1 broke the regulation of pump operation on the part of a cell turgor.

[Reversibility of the proton-potassium pump and synthesis of ATP in E. coli].

E. coli is able to substitute 2H+ from the external medium for one K+ of a cell with the concurrent synthesis of ATP under certain condition. The 2H+/K+ exchange and coupled ATP synthesis are in need of both the essential H+ (around 24 KJ) and the high K+ gradient (10(3) ) directed from a cell to the medium.

[Ion-exchanging ratio and membrane potential in the bacterium S. faecalis].

The membrane potentials (delta psi) in S. faecalis equal to -140 mV were measured by means of TPP+-electrodes. The values of delta psi remain constant under temperature variation from 37 degrees to 18 degrees C.

[Model of proton-potassium transport systems].

Previous experimental results are discussed. It was shown that two H+--K+-exchange systems operate in the E. coli membranes and that they can be stopped by N,N'-dicyclohexylcarbodiimide.

[Systems of H+ K+ ion exchange in E. coli].

Membrane potentials in bacteria E. coli have been estimated by means of electrodes for determination of activity of tetraphenilphosphonium ions in the medium. The strain E.

[Systems of H+-K+-exchange in E. coli. Interplay with ATPase complex F1.F0].

A study has been made of the nature of H+-K+-exchanges in the strain E. coli AN 120 with mutation in gene uncA401 (the defect in Mg++-Ca++-ATPase) and in the strain E. coli AN 382 with mutation in gene uncB (F0 is insensitive to N,N1-dicyclohehylcarbodiimide, DCCD).