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BACKGROUND: Virtual reality (VR) is an effective technique to reduce cost and increase fidelity in training programs. In VR, visual and vestibular cues are often in conflict, which may result in simulator-induced motion sickness. The purpose of this study is to investigate the integration of Galvanic Vestibular Stimulation (GVS) with a VR flight training simulator by assessing flight performance, secondary task performance, simulator sickness and presence.METHODS: There were 20 participants who performed 2 separate VR flight simulation sessions, with and without GVS (control). Flight performance, secondary task performance, and electrogastrogram were measured during VR flight simulation. The standardized simulator sickness and presence questionnaires were administered.RESULTS: Electrogastrogram measures such as dominant power instability coefficient (DPIC) and percentages of bradygastric waves (%B) were lower in the GVS session than the control session in the flight simulation (DPIC: 0.44 vs. 0.54; %B: 21.2% vs. 30.5%) and postflight (DPIC: 0.38 vs. 0.53; %B: 22.8% vs. 31.4%) periods. Flight performance (#hit-gates) was improved in the GVS session compared to the control (GVS: 17, Control: 15.5). Secondary task performance (%hits) was improved with GVS for the Easy task (GVS: 55.5%, Control: 43.1%).DISCUSSION: This study demonstrates the potential of synchronizing GVS with visual stimuli in VR flight training to reduce visual-vestibular sensory conflict to improve fidelity and performance. These results provide initial evidence, but continued research is warranted to further understand the benefits and applications of GVS in VR simulator training.Pradhan GN, Galvan-Garza RC, Perez AM, Stepanek J, Cevette MJ. Visual vestibular conflict mitigation in virtual reality using galvanic vestibular stimulation. Aerosp Med Hum Perform. 2022; 93(5):406–414.

INTRODUCTION: For over 50 yr, investigators have studied the physiological adaptations of the human system during short- and long-duration spaceflight exposures. Much of the knowledge gained in developing health countermeasures for astronauts onboard the International Space Station demonstrate terrestrial applications. To date, a systematic process for translating these space applications to terrestrial human health has yet to be defined.METHODS: In the summer of 2017, a team of 38 international scientists launched the Bellagio ll Summit Initiative. The goals of the Summit were: 1) To identify space medicine findings and countermeasures with highest probability for future terrestrial applications; and 2) To develop a roadmap for translation of these countermeasures to future terrestrial application. The team reviewed public domain literature, NASA databases, and evidence books within the framework of the five-stage National Institutes of Health (NIH) translation science model, and the NASA two-stage translation model. Teams then analyzed and discussed interdisciplinary findings to determine the most significant evidence-based countermeasures sufficiently developed for terrestrial application.RESULTS: Teams identified published human spaceflight research and applied translational science models to define mature products for terrestrial clinical practice.CONCLUSIONS: The Bellagio ll Summit identified a snapshot of space medicine research and mature science with the highest probability of translation and developed a Roadmap of terrestrial application from space medicine-derived countermeasures. These evidence-based findings can provide guidance regarding the terrestrial applications of best practices, countermeasures, and clinical protocols currently used in spaceflight.Sides MB, Johnston SL III, Sirek A, Lee PH, Blue RS, Antonsen EL, Basner M, Douglas GL, Epstein A, Flynn-Evans EE, Gallagher MB, Hayes J, Lee SMC, Lockley SW, Monseur B, Nelson NG, Sargsyan A, Smith SM, Stenger MB, Stepanek J, Zwart SR; Bellagio II Team. Bellagio II report: terrestrial applications of space medicine research. Aerosp Med Hum Perform. 2021; 92(8):650669.

DEMO fusion power reactor features multiple different grade heat sources, like the first wall and blanket, divertor, and vacuum vessel. The way of using these sources and their compatibility with the power conversion cycle will affect the efficiency of electricity production. A significant complication is a pulse operation of the fusion reactor unless the noninductive generation of the plasma electric current is developed. In this case, an energy storage application is necessary for conventional electricity production. This article is focused on the supercritical CO2 power conversion Brayton cycle and on optimization of selected S-CO2 layouts with the integrated energy storage. The purpose is to compare the efficiency of selected cycle layouts and to find the highest efficiency layout with the multiple different grade heat sources and energy storage.

Tuned mass damper is a device, which can be highly useful when dealing with excessive vibration and is widely used in many engineering fields. However, its proper design and optimization is a complicated task. This study uses mode superposition method to speed up the evaluation of dynamic response. The speed of response calculation allows for a quick calculation of frequency response function and numerical optimization of tuned mass dampers. This optimization method is demonstrated on a numerical example of a cable stayed footbridge. The example compares a simplified and widely used design method of tuned mass damper with numerical optimization.

BACKGROUND: Severe acute hypoxia results in a rapid deterioration of cognitive functioning and thus poses a risk for human operations in high altitude environments. This study aimed at investigating the effects of oxygen system failure during a high-altitude high-opening (HAHO) parachute jump scenario from 30,000 ft (9144 m) on human physiology and cognitive performance using a noncontact eye-tracking task.METHODS: Nine healthy male volunteers (ages 27–48) were recruited from the Norwegian Special Operations Commandos. Eye-tracking data were collected to derive information on cognitive performance in the context of rapid dynamic changes in pressure altitude while performing a modified King-Devick test. The baseline data was collected at 8000 ft (2438 m) while breathing 100% oxygen during decompression. For every test, the corresponding arterial blood gas analysis was performed.RESULTS: The study subjects endured severe hypoxia, which resulted in significant prolongations of fixation time (range: 284.1–245.6 ms) until 23,397 ft (131 m) and fixation size (range: 34.6–32.4 mm) until 25,389 ft (7739 m) as compared to the baseline (217.6 ± 17.8 ms and 27.2 ± 4.5 mm, respectively). The increase in the saccadic movement and decrease in the saccadic velocity was observed until 28,998 ft and 27,360 ft (8839 and 8339 m), respectively.DISCUSSION: This is the first study to investigate cognitive performance from measured oculometric variables during severe hypobaric hypoxia in a simulated high-altitude airdrop mission scenario. The measurement of altered oculometric variables under hypoxic conditions represents a potential avenue to study altered cognitive performance using noncontact sensors that can derive information and serve to provide the individual with a warning from impending incapacitation.Pradhan GN, Ottestad W, Meland A, Kåsin JI, Høiseth LØ, Cevette MJ, Stepanek J. Oculometric feature changes during acute hypoxia in a simulated high-altitude airdrop scenario. Aerosp Med Hum Perform. 2021; 92(12):928–936.

The first part of this article focuses on proposal of the appropriate cooling cycle for the specific fusion reactor. Furthermore, cooling technology of fusion power plant, two supercritical CO2 Brayton cycles and its positive and negative aspects are described. Additionally, comparison of cycles in terms of difficulty and possibilities of using more resources at once are depicted. This work also gives a principal preview of main technical parameters of supercritical CO2 cooling system. The second part describes the optimization of suggested design in order to maximize power of a fusion power plant and new computational software for optimization of the cooling cycles therewith, which would be also useful in the field of nuclear power engineering. The results of this article is comparison of efficiencies, power and other physical parameters of two layouts.

Medical Issues in Civilian Spaceflight As space travel expands to include civilian populations in addition to trained astronauts, physicians and space medicine experts will need to collaborate to a...

Oxygen is viewed in medicine as the sole determinant of tissue oxygenation, though carbon dioxide homeostasis is equally important and clinically often ignored. The aims of this study were as follows: (a) to examine the effects of different acute hypoxic conditions on partial pressure of arterial oxygen (PaO2), arterial oxygen saturation of hemoglobin (SaO2), and regional cerebral saturation of hemoglobin (rSO2); and (b) to evaluate supplemental CO2 as a tool to improve oxygenation in acutely hypoxic individuals. We hypothesized that exposure to gas mixtures with added CO2 would improve oxygenation in hypoxic human subjects. Twenty healthy subjects were exposed to 5‐min intervals of two gas mixtures: hypoxic gas mixture containing 8% oxygen, and a CO2‐enriched mixture containing 8% oxygen plus either 3% or 5% CO2. Ten subjects received the 3% CO2‐enriched mixture, and the remaining 10 subjects received the 5% CO2‐enriched mixture. The order of exposure was randomized. Blood gases, pulse oximetry, end‐tidal CO2, and cerebral oximetry were measured. Compared to the purely hypoxic gas group, PaO2 was increased in the 3% and 5% CO2‐enriched groups by 14.9 and 9.5 mmHg, respectively. Compared to pure hypoxia, SaO2 was increased in the 3% and 5% CO2‐enriched groups by 16.8% and 12.9%, respectively. Both CO2‐enriched gas groups had significantly higher end‐exposure rSO2 and recovered to baseline rSO2 within 1 min, compared to the pure hypoxic gas group, which returned to baseline in 5 min. These results suggest that in acutely hypoxic subjects, CO2 supplementation improves blood oxygen saturation and oxygen tension as well as cerebral oxygenation measures., Compared to pure hypoxia, SaO2 was increased in the 3% and 5% CO2‐enriched groups by 16.8% and 12.9%, respectively. Both CO2‐enriched gas groups had significantly higher end‐exposure rSO2 and recovered to baseline rSO2 within 1 min, compared to the pure hypoxic gas group, which returned to baseline in 5 min. These results suggest that in acutely hypoxic subjects, CO2 supplementation improves blood oxygen saturation and oxygen tension as well as cerebral oxygenation measures.

MV distribution grids are often operated with arc suppression coils compensating dominating reactive fault current component when single-phase ground fault occurs. The paper deals with an active compensation in emulated distribution grid of 10 kV performed by a proposed three-phase active fault compensator, based on power semiconductor converter. It enables a complete fault current compensation without residual components and to address resonance-related problems.

Based on the requirements of F4E organization, an experimental device HELCZA (High Energy Load Czech Assembly) was designed for high heat flux cyclic loading of plasma-facing components of the ITER reactor, primarily for testing of the full-size first wall modules and divertor inner vertical targets. This article presents a design of the HELCZA shielding frame for the divertor inner vertical targets irradiation by the electron beam with a power density of 40 MW/m2. The design includes the choice of the geometric shape of the frame, determines the frame heat load and provides thermohydraulic calculations for the frame cooling, including the determination of pressure losses.

Nowadays, the technology of fusion power reactors faces various engineering obstacles. One of the most discussed topics is the pulse and dwell period of the fusion power reactor, which may be the most challenging for material engineering, electrical power grid, energy storage systems, etc. The main goal of this research is to calculate the optimized parameters for power cycles to gain the highest efficiency. This article also describes the optimization method of a possible supercritical CO 2 power conversion cycle in DEMO. For comparison, there were chosen two Brayton power cycle layouts using S-CO 2 . The calculation focuses on the optimization due to the difference between the gained electrical power for these two periods, which lowers the oscillations in the power output. Besides, the approach of calculation via upgraded software for the power conversion cycles optimization is described. The optimization of this specific DEMO design points to the simple Brayton cycle as a better choice due to simplicity, higher flexibility and slightly higher gross efficiency.

One of the fundamental issues of the pulse fusion power plants is the appropriate storage of thermal energy during the burn phase and idle phase to ensure the steady-state thermal and flow conditions of the coolant through the turbine. Accumulation of power into the solid heat accumulator is one of the feasible solutions, which, together with its controlled bypass, would allow to achieve steady-state coolant parameters during the burn and idle phases. This paper presents a prototypal model of the solid energy storage. The model is based on the CFD parametric calculations that determine the thermal and flow characteristics of the storage depending on its charge status.

The main goal of this study is to propose a comprehensive view of the benefits of using various working media and thermal cycle layouts for efficient conversion of thermal energy from the helium-cooled DEMO reactor for electricity production. A four-source boundary condition proposed by Bubelis (2018) [1] is used in the power cycle optimization process. Selected power cycle layouts are optimized through a specialized computational optimization code to achieve maximum net power output with variable blanket helium outlet temperature in the range from 380 up to 520 °C. The selected working media are water-steam, supercritical CO2, and helium. The Rankine cycle layout is based on the layout proposed by Rovira (2019) [7] and optimized in the full range of blanket outlet temperature. Investigated S-CO2 cycles are simple Brayton cycle, re-compression cycle, and pre-compression cycle. In the case of the indirect helium cycle, the only reasonable layouts are the simple Brayton cycle and the pre-compression cycle. Study results compare suitability of using the water-steam, S-CO2, and helium cycles for different outlet temperatures of the source as well as a view of their complexity in terms of size and number of components. Presented results show, that the Rankine cycle is the most effective solution from thermodynamics point of view, but S-CO2 cycles can compete with it in size, complexity, cost, and operational flexibility.

High-altitude ascent induces left (LV) and right (RV) ventricular adaptations secondary to hypoxia-related hemodynamic and myocardial alterations. Since cardiopulmonary decrements observed with aging (e.g., decreased LV compliance and increased pulmonary vascular resistance) may limit cardiac plasticity, this study examined myocardial adaptability throughout an 11 day sojourn to 5893 m in young and older-aged trekkers.Echocardiography was performed on 14 young (8 men; 32 ± 5 years) and 13 older-aged (8 men; 59 ± 5 years) subjects on non-trekking days (Day 0: 880 m; Day 3: 3100 m; Day 8: 4800 m; Day 12/post-climb: 880 m). RV systolic pressure (mmHg) was systematically higher in older-aged subjects (p 0.01) with similar progressive increases observed during ascent for young and older subjects, respectively (Day 0: 18 ± 1 vs 20 ± 2; Day 3: 25 ± 2 vs 29 ± 3; Day 8: 30 ± 2 vs 35 ± 2). Estimates of LV filling pressure (E/E') were systematically higher in older subjects (p 0.01) with similar progressive decreases observed during ascent for young and older-aged subjects, respectively (Day 0: 5.6 ± 0.3 vs 6.7 ± 0.5; Day 3: 5.1 ± 0.2 vs 6.1 ± 0.3; Day 8: 4.7 ± 0.3 vs 5.4 ± 0.3). Overall, RV end-diastolic and end-systolic area increased at altitude (p 0.01), while LV end-diastolic and end-systolic volume decreased (p 0.01). However, all RV and LV morphological measures were similar on Day 3 and Day 8 (p 0.05), and returned to baseline post-climb (p 0.05). Excluding mild LV dilatation in some older-aged trekkers on Day 8/Day 12 (p 0.01), altitude-induced morphological and functional adaptations were similar for all trekkers (p 0.05).Altitude-induced myocardial adaptations are chamber specific, secondary to RV and LV hemodynamic alterations. Despite progressive hemodynamic alterations during ascent, morphological and functional cardiac perturbations plateaued, suggesting rapid myocardial adaptation which was mostly comparable in young and older-aged individuals.

Cooling system is one of the most important part of the power plants and cooling systems based on S-CO2 (Supercritical Carbon Dioxide) coolant seems nowadays perspective alternative to Helium and Rankine steam power cycles. Due to many advantages of S-CO2, these cooling systems are researched on many institutions and the results confirm that it should be successful for the future cooling systems design. One of the main objectives is comparison of the possible cooling mediums of DEMO2 (Demonstration power plant 2) with focusing on different power cycles with S-CO2. The First part of this article targets on comparison of three main coolants: steam, helium and S-CO2. The second part of this article focuses on the new software called CCOCS (Cooling Cycles Optimization Computational Software) which was developed on CTU in Prague. This software works on deeper optimization of the power cycles with various coolants and initial conditions. The third part describes advanced S-CO2 power cycles and enlarges past research, which was based on optimization of S-CO2 Brayton Simple power cycle and S-CO2 Re-compression power cycle both with recuperation and their usage in fusion and Fission energy engineering. It is possible to heighten thermodynamic efficiency of power cycle by changing the layout of the power cycle and the main objective of this paper is to compare four advanced layouts, describe the results of the optimization of these cycles and outline advantages and disadvantages of chosen optimized layouts.

This paper deals with the verification of the maximum current rating of MOSFET transistors in a discrete package TO-247AC. The main motivation for this analysis was the redesign of AC power drive chain for electric go kart with three phase power converter of the output nominal power 10kW, a supply voltage 48V and minimal switching frequency 50kHz. The inverter must be able to operate with short-term current overload up to 450A. A parallel combination of three power transistors is used to design the basic power switch. The HEXFET Power MOSFET transistor (IRFP4468PdF in a discrete case TO-247AC) was chosen as a basic structural element. We used DC analysis to verify the properties and limits of the discrete case TO-247AC. The maximum rated current through the MOSFET transistor was determined with respect to the maximum chip temperature and enclosure limitation. In order to accurately verify the measuring results of transistor temperature, a thermo-camera was used (the color is used to define the emissivity of measured object with reference e = 0,9). Temperature was also measured by a thermometer PT100 sensor and estimated from the forward voltage on freewheeling diode.

This paper deals with heatsink design and verification of IGBT-based full-bridge converter of rated power 150 kVA. The converter is designed for air cooling-based installation of total power 1.35 MVA operating in medium-voltage power system. In order to exactly determine the cooling ability of the designed system, dc current analysis has been applied to IGBT modules connected in series.

This paper deals with optimal electron beam heat distribution on the HELCZA experiment while calculating flatness of the heat input distribution and distribution of surface temperature for various samples. A new dedicated computer program has been developed for balancing the heat flux in the construction materials of the sample. The first boundary condition for this calculation were distribution functions describing the process of heat input from the electron beam. The beam power distribution is described via a beam shape Gaussian function and a screening pattern on the irradiated surface. The second boundary condition was cooling of the material by the refrigerant cooling ducts. While the heat input from the electron beam is relatively flat, the distribution of subsurface cooling channels and the design of individual elements of the sample leads to significant surface temperature distortions in the sample material. Depending on the method of scanning and relative beam position, a complex problem of heat conduction had to be solved numerically. The newly developed computer program solves the above problem and balances the given system of equations of heat conduction and it can then describe in detail the nature of the surface temperature of the sample as well as temperatures below its surface. The outputs are temperature profiles during heating, a comprehensive view of the temperature distribution in the sample and temperature profiles in selected areas below the surface of the sample. Due to good thermal conductivity of structural metal materials, low heat capacity and a sufficiently long time of irradiation the task was treated as stationary. As part of the solution the sample surfaces scanning pattern by electron beam was optimized.

Effective use of fusion energy goes hand in hand with effective energy recovery of the generated heat. One of the most promising working medium suitable for this purpose is supercritical carbon dioxide (S-CO2) due to its thermal properties. Six S-CO2 cycle layouts were optimized for the effective use of the heat generated in the DEMO fusion reactor. The main investigated parameter is the outlet temperature from the blanket and the first wall. The temperature range is 350–550 °C. The second parameter is the compressor intake temperature at two temperature levels 25 and 31 °C. The analysis of thermodynamic cycles was performed using new custom-built high-performance computing software. The parametric study of each layout shows the suitability of the given cycle for heat recovery and its sensitivity to the main heat source temperature.

In this paper, we focus on the application of oculometric patterns extracted from raw eye movements during a mental workload task to assess changes in cognitive performance in healthy youth athletes over the course of a typical sport season. Oculometric features pertaining to fixations and saccades were measured on 116 athletes in pre- and post-season testing. Participants were between 7 and 14 years of age at pre-season testing. Due to varied developmental rates, there were large interindividual performance differences during a mental workload task consisting of reading numbers. Based on different reading speeds, we classified three profiles (slow, moderate, and fast) and established their corresponding baselines for oculometric data. Within each profile, we describe changes in oculomotor function based on changes in cognitive performance during the season. To visualize these changes in multidimensional oculometric data, we also present a multidimensional visualization tool named DiViTo (diagnostic visualization tool). These experimental, computational informatics and visualization methodologies may serve to utilize oculometric information to detect changes in cognitive performance due to mild or severe cognitive impairment such as concussion/mild traumatic brain injury, as well as possibly other disorders such as attention deficit hyperactivity disorders, learning/reading disabilities, impairment of alertness, and neurocognitive function.

High power ultra-fast charging station for public transport systems becomes integral part of an urban power grid. In some cases the station has to be supplied by existing power grid 3×400VAC. This paper describes charging station based on a cost-effective topology with an output power over 300kW intended for charging electrical busses. Main part is focused on control algorithm proposal. Performance is verified by a simulation of steady-state and transient conditions.

There is a need for a practical objective measure to detect mild changes in cognitive performance as early signs of concussion in youth or other special populations. In this paper, we propose a novel correlation model that establishes the relationship between oculometrics extracted from raw eye movements during a mental workload task and cognitive performance. We assessed differences in cognitive performance in terms of age for youth athletes based on oculometrics pertaining to fixations and saccades. In this cross-sectional study, oculometrics were measured on 440 healthy youth athletes aged 7 to 15 years. Oculometrics pertaining to fixations (fixation time, fixation size, and surface area of fixation) and saccades (total saccadic amplitude, average saccadic amplitude, and saccadic velocity) were measured and compiled into a multivariate oculometric database by age. We discovered that the combined power of fixations and saccades provided the strongest correlation with cognitive performance—a finding that is evident across all ages as well as all levels of mental workload difficulty. Specifically, the combined observations of fixation time, saccadic velocities, and saccadic amplitudes provided us an understanding of cognitive performance during different levels of mental workload difficulty across all age groups. This study is the first step towards establishing normative, multi-dimensional oculometrics for fixations and saccades in young athletes (7 to 15 years) who are at risk for concussion in sports and recreational activities.

High-Altitude High Opening (HAHO) is a military operational procedure in which parachute jumps are performed at high altitude requiring supplemental oxygen, putting personnel at risk of acute hypoxia in the event of oxygen equipment failure. This study was initiated by the Norwegian Army to evaluate potential outcomes during failure of oxygen supply, and to explore physiology during acute severe hypobaric hypoxia. A simulated HAHO without supplemental oxygen was carried out in a hypobaric chamber with decompression to 30,000 ft (9,144 m) and then recompression to ground level with a descent rate of 1,000 ft/min (305 m/min). Nine subjects were studied. Repeated arterial blood gas samples were drawn throughout the entire hypoxic exposure. Additionally, pulse oximetry, cerebral oximetry, and hemodynamic variables were monitored. Desaturation evolved rapidly and the arterial oxygen tensions are among the lowest ever reported in volunteers during acute hypoxia. PaO2 decreased from baseline 18.4 (17.3–19.1) kPa, 138.0 (133.5–143.3) mmHg, to a minimum value of 3.3 (2.9–3.7) kPa, 24.8 (21.6–27.8) mmHg, after 180 (60–210) s, [median (range)], N = 9. Hyperventilation with ensuing hypocapnia was associated with both increased arterial oxygen saturation and cerebral oximetry values, and potentially improved tolerance to severe hypoxia. One subject had a sharp drop in heart rate and cardiac index and lost consciousness 4 min into the hypoxic exposure. A simulated high-altitude airdrop scenario without supplemental oxygen results in extreme hypoxemia and may result in loss of consciousness in some individuals. NEW & NOTEWORTHY This is the first study to investigate physiology and clinical outcome of oxygen system failure in a simulated HAHO scenario. The acquired knowledge is of great value to make valid risk-benefit analyses during HAHO training or operations. The arterial oxygen tensions reported in this hypobaric chamber study are among the lowest ever reported during acute hypoxia.

INTRODUCTION: Visual performance impairment after hypoxia is well recognized in military and civilian aviation. The aims of this study were: 1) to assess oculometric features such as blink metrics, pupillary dynamics, fixations, and saccades as cognitive indicators of early signs of hypoxia; and 2) to analyze the impact of different hypoxic conditions ["hypoxic hypoxia" (HH) and "isocapnic hypoxia" (IH)] on specified oculometrics during mental workloads. METHODS: Oculometric data were collected on 25 subjects under 3 conditions: normoxia, HH (8% O2 + balance N2), and IH (7% O2 + 5% CO2 + balance N2). The mental workload task consisted of reading aloud linear arrays of numbers after exposure to gas mixtures. RESULTS: Blink rates were significantly increased under hypoxic conditions (by +100.7% in HH and by +92.8% in IH compared to normoxia). A faster recovery of blink rate was observed in transitioning from IH (23.6% vs. 76.3%) to normoxia. The percentage change in pupil size fluctuation was increased under HH more than under IH (29% vs. 4.4%). Under HH average fixation time and target area size were significantly higher than under IH. Total saccadic times under hypoxic conditions were significantly increased compared with normoxia. CONCLUSIONS: These results suggest that oculometric changes are indicators of hypoxia, which can be monitored using compact, portable, noninvasive eye-tracking devices in a cockpit analogous environment to detect hypoxia-induced physiological changes in aircrew. Comparative results between HH and IH support the potential role of carbon dioxide in augmenting cerebral perfusion and hence improved tissue oxygen delivery. Language: en

Introduction Simulator sickness causes vestibulo-autonomic responses that increase sympathetic activity and decrease parasympathetic activity. The purpose of the study was to quantify these responses through electrogastrography and cardiac interbeat intervals during flight simulation. Methods There were 29 subjects that were randomly assigned to 2 parallel arms: (1) oculovestibular recoupling, where galvanic vestibular stimulation was synchronous with the visual field; and (2) control. Electrogastrography and interbeat interval data were collected during baseline, simulation, and post-simulation periods. A simulator sickness questionnaire was administered. Results Statistically significant differences were observed in percentage of recording time with the dominant frequency of electrogastrography in normogastric and bradygastric domains between the oculovestibular recoupling and control groups. Normogastria was dominant during simulation in the oculovestibular recoupling group. In the control group, the percentage of recording time with the dominant frequency decreased by 22% in normogastria and increased by 20% in bradygastria. The percentage change of the dominant power instability coefficient from baseline to simulation was 26% in the oculovestibular recoupling group vs. 108% in the control group. The power of high-frequency components for interbeat intervals did not change significantly in the oculovestibular recoupling group and was decreased during simulation in the control group. Discussion Electrogastrography and interbeat intervals are sensitive indices of autonomic changes in subjects undergoing flight simulation. These data demonstrate the potential of oculovestibular recoupling to stabilize gastric activity and cardiac autonomic changes altered during simulator and motion sickness.

Introduction Hypoxic incapacitation continues to be a significant threat to safety and operations at high altitude. Noninvasive neurocognitive performance testing is desirable to identify presymptomatic cognitive impairment, affording operators at altitude a tool to quantify their performance and safety. Methods There were 25 subjects enrolled in this study. Cognitive performance was assessed by using the King-Devick (K-D) test. The performance of the subjects on the K-D test was measured in normoxia followed by hypoxia (8% 02 equivalent to 7101 m) and then again in normoxia. Results K-D test completion time in hypoxia for 3 min was significantly longer than the Baseline Test (54.5 +/- 12.4 s hypoxic vs. 46.3 +/- 10.4 s baseline). Upon returning to normoxia the completion time was significantly shorter than in hypoxia (47.6 +/- 10.6 s post test vs. 54.5 +/- 12.4 s hypoxic). There was no statistically significant difference between baseline test and post test times, indicating that all subjects returned to their normoxic baseline levels. SpO2 decreased from 98 +/- 0.9% to 80 +/- 7.8% after 3 min on hypoxic gas. During the hypoxic K-D test, SpO2 decreased further to 75.8 +/- 8.3%. Conclusions In this study the K-D test has been shown to be an effective neurocognitive test to detect hypoxic impairment at early presymptomatic stages. The K-D test may also be used to afford a reassessment of traditional measures used to determine hypoxic reserve time.

Supercritical carbon dioxide cycles are recently very perspective and they are researched all around the world. CO2 is an interesting medium for applications in many technologies, from nuclear energy through geothermal, solar and waste heat recovery systems. However, S-CO2 cycles have several issues which have to be researched, one of them being the presence of the so called pinch point in the heat exchangers design. Therefore, the Czech Technical University (CTU) conducts research on supercritical carbon dioxide cycles, which are focused on the effect of the gaseous admixtures in S-CO2 on different cycle components. The research is primarily focused on the pinch point shift within heat exchangers caused by gaseous admixtures. Previous work has shown that the pinch point can be removed with the addition of small amounts of another gases. However, it is also important to describe the effect on the performance of the cycles. This is the main topic of this paper. One of the reasons for this research is the positive effects on components are possible. The first part of the study is focused on the development of computational code for calculation of the basic S-CO2 cycles with mixtures. The second part of the study is focused on the calculation of basic cycles for binary mixtures. The calculation will be performed for pure CO2 and some binary mixture. He, CO, O2, N2, Ar will be used for the calculation as the most common admixtures, furthermore H2, CH4 and H2S will be used as well. The last part of the study will be focused on the optimization of individual cycles for different amount of admixtures in CO2. The result of this study will define the optimum ratio of admixtures and description of their effect on cycle efficiency.

We describe a novel, interprofessional educational intervention pilot used to orient new health profession employees through the simulation laboratory. Health profession employees were recruited to engage in a simulation training session that focused on communication, collaboration, and healthcare roles and responsibilities. Learners (N = 11) were divided into two groups with representation from various health disciplines. Each group participated in a simulated patient scenario while the other group actively observed in another classroom. At the end of both sessions, the group reconvened for a debriefing session. Participants were given a survey before and after the training session, to evaluate the content, experience, and value to their practice. The pre- and post-evaluation survey analysis showed improvement in all objectives with a mean (SD) pre-evaluation score of 4.10 (0.40-1.01) and mean (SD) post-evaluation score of 4.73 (0.30-0.81). Results were favourable, and plans to expand this project are under way.

This paper describes a prospective design concept of a hard switching input voltage stabilizer for the auxiliary drives converters of dc catenary fed light traction vehicles. Auxiliary drives are mostly dedicated to generate standard power grid that supplies various on-board equipment and charging on-board batteries. The input voltage stabilizer (IVS) is the first input block of auxiliary drives. This block defines the voltage level of the consequent dc/dc isolated converter (IC). The main aim of this paper is to present the reader with the design of a low-cost variant of the voltage stabilizer. The described input voltage stabilizer is designed as a buck (step-down) or boost (step-up) converter, operating with an input catenary voltage range of 400 (VDC) to 950 VDC. The new fast, discrete IGBT H3 transistors and SiC diodes allow switching frequency from 20 kHz to 30 kHz in a hard switching mode with power rated up to 22 kW. DOI: http://dx.doi.org/10.5755/j01.eee.21.6.13752

The value of epicardial adipose tissue (EAT) thickness as determined by echocardiography in cardiovascular risk assessment is not well understood. The aim of this study was to determine the associations between EAT thickness and Framingham risk score, carotid intima media thickness, carotid artery plaque, and computed tomographic coronary calcium score in a primary prevention population.Patients presenting for cardiovascular preventive care (n = 356) who underwent echocardiography as well as carotid artery ultrasound and/or coronary calcium scoring were included.EAT thickness was weakly correlated with Framingham risk score. The prevalence of carotid plaque was significantly greater in those with EAT thickness ≥ 5.0 mm who either had low Framingham risk scores or had body mass indexes ≥ 25 kg/m(2), compared with those with EAT thickness5.0 mm. No significant association between EAT thickness and carotid intima-media thickness or coronary calcium score existed.EAT thickness ≥ 5.0 mm may identify an individual with a higher likelihood of having detectable carotid atherosclerosis.

BACKGROUND: Commercial spaceflight participants on orbital flights typically are older than career astronauts and they often have medical conditions that have not been studied at high g or in microgravity. This is a case report of a 56-yr-old orbital spaceflight participant with essential tremor and frequent premature ventricular contractions that occurred at rates up to 7000 per day. Before training and spaceflight, he was required to complete extensive clinical investigations to demonstrate normal cardiac structures and the absence of cardiac pathology. The evaluation included signal averaged ECG, transthoracic stress echocardiography, exercise tolerance tests, electrophysiological studies, cardiac MRI, electron beam CT, Holter monitoring, and overnight oximetry. While no cardiac pathology was demonstrated, the Russian medical team required that the PVCs be treated prior to training and spaceflight. For the initial flight, a selective beta-1 receptor beta blocker was used and for the second a calcium channel blocker was used in combination with a nonselective beta blocker for tremor control. Analogue environment testing assured that this combination of medications was compatible. CONCLUSION: The spaceflight participant's PVCs were incompletely suppressed with a low-dose selective beta-1 blocker, but were well suppressed by a calcium channel blocker. He tolerated in-flight periodic use of a nonselective beta blocker in combination with a calcium channel blocker. In-flight ECG and blood pressure monitoring results were normal, and an ECG obtained midmission and on landing day showed successful PVC suppression. He did not have any cardiac difficulty with launch, on-orbit operations, entry, or recovery

The arterial pulse has historically been an essential source of information in the clinical assessment of health. With current sphygmomanometric and oscillometric devices, only the peak and trough of the peripheral arterial pulse waveform are clinically used. Several limitations exist with peripheral blood pressure. First, central aortic pressure is a better predictor of cardiovascular outcome than peripheral pressure. Second, peripherally obtained blood pressure does not accurately reflect central pressure because of pressure amplification. Lastly, antihypertensive medications have differing effects on central pressures despite similar reductions in brachial blood pressure. Applanation tonometry can overcome the limitations of peripheral pressure by determining the shape of the aortic waveform from the radial artery. Waveform analysis not only indicates central systolic and diastolic pressure but also determines the influence of pulse wave reflection on the central pressure waveform. It can serve as a useful adjunct to brachial blood pressure measurements in initiating and monitoring hypertensive treatment, in observing the hemodynamic effects of atherosclerotic risk factors, and in predicting cardiovascular outcomes and events. Radial artery applanation tonometry is a noninvasive, reproducible, and affordable technology that can be used in conjunction with peripherally obtained blood pressure to guide patient management. Keywords for the PubMed search were applanation tonometry, radial artery, central pressure, cardiovascular risk, blood pressure, and arterial pulse. Articles published from January 1, 1995, to July 1, 2009, were included in the review if they measured central pressure using radial artery applanation tonometry.

The purpose of this report was to illustrate how thoracic gas compression (TGC) artifact, and differences in air density, may together conflate the interpretation of changes in the forced expiratory flows (FEFs) at high altitude (>2400 m). Twenty‐four adults (10 women; 44 ± 15 year) with normal baseline pulmonary function (>90% predicted) completed a 12‐day sojourn at Mt. Kilimanjaro. Participants were assessed at Moshi (Day 0, 853 m) and at Barafu Camp (Day 9, 4837 m). Typical maximal expiratory flow‐volume (MEFV) curves were obtained in accordance with ATS/ERS guidelines, and were either: (1) left unadjusted; (2) adjusted for TGC by constructing a “maximal perimeter” MEFV curve; or (3) adjusted for both TGC and differences in air density between altitudes. Forced vital capacity (FVC) was lower at Barafu compared with Moshi camp (5.19 ± 1.29 L vs. 5.40 ± 1.45 L, P

Future long-duration spaceflights are now being planned to the Moon and Mars as a part of the "Vision for Space Exploration" program initiated by NASA in 2004. This report describes the design reference missions for the International Space Station, Lunar Base, and eventually a Mars Expedition. There is a need to develop more stringent preflight medical screening for crewmembers to minimize risk factors for diseases which cannot be effectively treated in flight. Since funding for space life sciences research and development has been eliminated to fund program development, these missions will be enabled by countermeasures much like those currently in use aboard the International Space Station. Artificial gravity using centrifugation in a rotating spacecraft has been suggested repeatedly as a "universal countermeasure" against deconditioning in microgravity and could be an option if other countermeasures are found to be ineffective. However, the greatest medical unknown in interplanetary flight may be the effects of radiation exposure. In addition, a Mars expedition would lead to a far greater level of isolation and psychological stress than any space mission attempted previously; because of this, psychiatric decompensation remains a risk. Historically, mortality and morbidity related to illness and injury have accounted for more failures and delays in new exploration than have defective transportation systems. The medical care system on a future Mars expedition will need to be autonomous and self-sufficient due to the extremely long separation from definitive medical care. This capability could be expanded by the presence of a physician in the crew and including simple, low-technology surgical capability.

Wir berichten über einen 1971 geborenen Linienpiloten und Milizbordoperateur mit rezidivierender Diarrhoe sowie einem pruriginösen Exanthem an den Extremitäten seit der Adoleszenz. Gastroenterologische Abklärungen ergaben das Vorliegen einer Zöliakie (glutensensitive Enteropathie). Bei den Hautveränderungen handelte es sich um eine Dermatits herpetiformis Duhring, welche nicht selten in Zusammenhang mit der genannten Erkrankung auftritt. Mit Beginn einer glutenfreien Diät verschwanden sowohl die gastroenterologischen wie auch die dermatologischen Symptome vollständig. Der Pilot ist heute beschwerdefrei.

Understanding the quench front propagation during bottom core reflooding is crucial for the effective cooling during the LOCA accident. The results presented in this paper were obtained on an experimental loop with an annular test section. The test section consists of a vertical electrically heated stainless steel tube with outer diameter 9 mm and length of 1.7 m. The heated tube is placed inside a glass tube with the inner diameter 14.5 mm. Water mass flux during the reflooding is in the range from 100 kg.m−2.s−1 up to 140 kg.m−2.s−1 and the initial wall temperature of the stainless steel tube is in the range from 250 °C up to 800 °C. The presented results show the influence of the initial conditions on the quench front propagation and the complexity of the phenomenon.

Background: We aim to provide data on a diabetes technology simulation course (DTSC) that instructs internal medicine residents in the use of continuous subcutaneous insulin infusion (CSII) and continuous glucose monitoring system (CGMS) devices. Methods: The DTSC was implemented during calendar year 2012 and conducted in the institution's simulation center. It consisted of a set of prerequisites, a practicum, and completion of a web-based inpatient CSII-ordering simulation. DTSC participants included only those residents in the outpatient endocrinology rotation. Questionnaires were used to determine whether course objectives were met and to assess the satisfaction of residents with the course. Questionnaires were also administered before and after the endocrine rotation to gauge improvement in familiarity with CSII and CGMS technologies. Results: During the first year, 12 of 12 residents in the outpatient endocrinology rotation completed the DTSC. Residents reported that the course objectives were fully met. The mean satisfaction score with the course ranged from 4.0 to 4.9 (maximum, 5), with most variables rated above 4.5. Self-reported familiarity with the operation of CSII and CGMS devices increased significantly in the postrotation survey compared with that on the prerotation survey (both p < .01). Conclusions: In this pilot program, simulation-based education increased the perceived familiarity of residents with CSII and CGMS technologies. In light of these preliminary findings, the course will continue to be offered, with further data accrual. Future work will involve piloting the DTSC approach among other types of providers, such as residents in other specialties or inpatient nursing staff.

Sequence variation in 2.2 kb of non-coding regions of the chloroplast genome of eight dandelions (Taraxacum: Lactuceae) from Asia and Europe is interpreted in the light of the phylogenetic signal of base substitutions vs. indels (insertions-deletions). The four non-coding regions displayed a total of approximately 30 structural mutations of which 9 are potentially phylogenetically informative. Insertions, deletions, and an inversion were found that involved consecutive stretches of up to 172 bases. When compared to phylogenetic relationships of the chloroplast genomes based on nucleotide substitutions only, many homoplasious indels (33%) were detected that differed considerably in length and did not comprise simple sequence repeats typically associated with replication slippage. Though many indels in the intergenic spacers were associated with direct repeats, frequently, the variable stretches participated in inverted repeat stabilized hairpins. In each intergenic spacer or intron examined, nucleotide stretches ranging from 30 to 60 bp were able to fold into stabilized secondary structures. When these indels were homoplasious, they always ranked among the most stabilized hairpins in the non-coding regions. The association of higher order structures that involve both classes of repeats and parallel structural mutations in hot spot regions of the chloroplast genome can be used to differentiate among mutations that differ in phylogenetic reliability.Key words: Taraxacum, indel, non-coding chloroplast DNA, hairpin, evolution.

Summary legitimacy are determined, all valid names are given types, and type specimens are selected and quoted where available. Comments are confined to the nomenclatural status of the names; for important taxonomic synonyms the accepted names are given, and names considered correct are highlighted.