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https://www.readbyqxmd.com/read/28208391/band-instability-in-near-critical-fluids-subjected-to-vibration-under-weightlessness
#1
T Lyubimova, A Ivantsov, Y Garrabos, C Lecoutre, G Gandikota, D Beysens
Periodical patterns (bands) developing at the interface of two immiscible fluids under vibration parallel to interface are observed under zero-gravity conditions. Fluids are slightly below their liquid-vapor critical point where they behave in a scaled, universal manner. In addition, liquid and vapor densities are close and surface tension is very low. Linear stability analyses and direct numerical simulation show that this instability, although comparable to the frozen wave instability observed in a gravity field, is nonetheless noticeably different when gravity becomes zero...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28098275/the-initial-stages-of-melting-of-graphene-between-4000-k-and-6000-k
#2
Eric Ganz, Ariel B Ganz, Li-Ming Yang, Matthew Dornfeld
Graphene and its analogues have some of the highest predicted melting points of any materials. Previous work estimated the melting temperature for freestanding graphene to be a remarkable 4510 K. However, this work relied on theoretical methods that do not accurately account for the role of bond breaking or complex bonding configurations in the melting process. Furthermore, experiments to verify these high melting points have been challenging. Practical applications of graphene and carbon nanotubes at high temperatures will require a detailed understanding of the behavior of these materials under these conditions...
February 1, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28081223/high-intensity-jump-training-is-tolerated-during-60-days-of-bed-rest-and-is-very-effective-in-preserving-leg-power-and-lean-body-mass-an-overview-of-the-cologne-rsl-study
#3
Andreas Kramer, Jakob Kümmel, Edwin Mulder, Albert Gollhofer, Petra Frings-Meuthen, Markus Gruber
PURPOSE: Space agencies are looking for effective and efficient countermeasures for the degrading effects of weightlessness on the human body. The aim of this study was to assess the effects of a novel jump exercise countermeasure during bed rest on vitals, body mass, body composition, and jump performance. METHODS: 23 male participants (29±6 years, 181±6 cm, 77±7 kg) were confined to a bed rest facility for 90 days: a 15-day ambulatory measurement phase, a 60-day six-degree head-down-tilt bed rest phase (HDT), and a 15-day ambulatory recovery phase...
2017: PloS One
https://www.readbyqxmd.com/read/28061915/prevalence-predictors-and-prevention-of-motion-sickness-in-zero-g-parabolic-flights
#4
John F Golding, Aurore C Paillard, Hervé Normand, Stéphane Besnard, Pierre Denise
INTRODUCTION: Zero-G parabolic flight reproduces the weightlessness of space for short periods. However, motion sickness may affect some fliers. The aim was to assess the extent of this problem and to find possible predictors and modifying factors. METHODS: Airbus zero-G flights consist of 31 parabolas performed in blocks. Each parabola consisted of 20 s of 0 g sandwiched by 20 s of hypergravity of 1.5-1.8 g. The survey covered N = 246 person-flights (193 men, 53 women), ages (M ± SD) 36...
January 1, 2017: Aerospace Medicine and Human Performance
https://www.readbyqxmd.com/read/28039409/internal-jugular-pressure-increases-during-parabolic-flight
#5
David S Martin, Stuart M C Lee, Timothy P Matz, Christian M Westby, Jessica M Scott, Michael B Stenger, Steven H Platts
One hypothesized contributor to vision changes experienced by >75% of International Space Station astronauts is elevated intracranial pressure (ICP). While no definitive data yet exist, elevated ICP might be secondary to the microgravity-induced cephalad fluid shift, resulting in venous congestion (overfilling and distension) and inhibition of cerebrospinal and lymphatic fluid drainage from the skull. The objective of this study was to measure internal jugular venous pressure (IJVP) during normo- and hypo-gravity as an index of venous congestion...
December 2016: Physiological Reports
https://www.readbyqxmd.com/read/28027021/whole-body-movements-in-long-term-weightlessness-hierarchies-of-the-controlled-variables-are-gravity-dependent
#6
Claudia Casellato, Alessandra Pedrocchi, Giancarlo Ferrigno
Switching between contexts affects the mechanisms underlying motion planning, in particular it may entail reranking the variables to be controlled in defining the motor solutions. Three astronauts performed multiple sessions of whole-body pointing, in normogravity before launch, in prolonged weightlessness onboard the International Space Station, and after return. The effect of gravity context on kinematic and dynamic components was evaluated. Hand trajectory was gravity independent; center-of-mass excursion was highly variable within and between subjects...
December 27, 2016: Journal of Motor Behavior
https://www.readbyqxmd.com/read/28013406/simulated-microgravity-affects-some-biological-characteristics-of-lactobacillus-acidophilus
#7
Dongyan Shao, Linbo Yao, Muhammad Shahid Riaz, Jing Zhu, Junling Shi, Mingliang Jin, Qingsheng Huang, Hui Yang
The effects of weightlessness on enteric microorganisms have been extensively studied, but have mainly been focused on pathogens. As a major component of the microbiome of the human intestinal tract, probiotics are important to keep the host healthy. Accordingly, understanding their changes under weightlessness conditions has substantial value. This study was carried out to investigate the characteristics of Lactobacillus acidophilus, a typical probiotic for humans, under simulated microgravity (SMG) conditions...
December 24, 2016: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/27941928/dual-matter-wave-inertial-sensors-in-weightlessness
#8
Brynle Barrett, Laura Antoni-Micollier, Laure Chichet, Baptiste Battelier, Thomas Lévèque, Arnaud Landragin, Philippe Bouyer
Quantum technology based on cold-atom interferometers is showing great promise for fields such as inertial sensing and fundamental physics. However, the finite free-fall time of the atoms limits the precision achievable on Earth, while in space interrogation times of many seconds will lead to unprecedented sensitivity. Here we realize simultaneous (87)Rb-(39)K interferometers capable of operating in the weightless environment produced during parabolic flight. Large vibration levels (10(-2) g Hz(-1/2)), variations in acceleration (0-1...
December 12, 2016: Nature Communications
https://www.readbyqxmd.com/read/27920669/the-neurovestibular-challenges-of-astronauts-and-balance-patients-some-past-countermeasures-and-two-alternative-approaches-to-elicitation-assessment-and-mitigation
#9
REVIEW
Ben D Lawson, Angus H Rupert, Braden J McGrath
Astronauts and vestibular patients face analogous challenges to orientation function due to adaptive exogenous (weightlessness-induced) or endogenous (pathology-induced) alterations in the processing of acceleration stimuli. Given some neurovestibular similarities between these challenges, both affected groups may benefit from shared research approaches and adaptation measurement/improvement strategies. This article reviews various past strategies and introduces two plausible ground-based approaches, the first of which is a method for eliciting and assessing vestibular adaptation-induced imbalance...
2016: Frontiers in Systems Neuroscience
https://www.readbyqxmd.com/read/27883068/-cerebellar-contribution-to-visuo-attentional-alpha-rhythm-insights-from-weightlessness
#10
A M Cebolla, M Petieau, B Dan, L Balazs, J McIntyre, G Cheron
Human brain adaptation in weightlessness follows the necessity to reshape the dynamic integration of the neural information acquired in the new environment. This basic aspect was here studied by the electroencephalogram (EEG) dynamics where oscillatory modulations were measured during a visuo-attentional state preceding a visuo-motor docking task. Astronauts in microgravity conducted the experiment in free-floating aboard the International Space Station, before the space flight and afterwards. We observed stronger power decrease (~ERD: event related desynchronization) of the ~10 Hz oscillation from the occipital-parietal (alpha ERD) to the central areas (mu ERD)...
November 24, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27861601/the-development-of-drosophila-melanogaster-under-different-duration-space-flight-and-subsequent-adaptation-to-earth-gravity
#11
Irina V Ogneva, Stepan N Belyakin, Svetlana V Sarantseva
In prospective human exploration of outer space, the need to preserve a species over several generations under changed gravity conditions may arise. This paper demonstrates our results in the creation of the third generation of fruit fly Drosophila melanogaster (third-stage larvae) during the 44.5-day space flight (Foton-M4 satellite (2014, Russia)), then the fourth generation on Earth and the fifth generation again in conditions of the 12-day space flight (2014, in the Russian Segment of the ISS). The species preserves fertility despite a number of changes in the level of expression and content of cytoskeletal proteins, which are the key components of the cleavage spindle and the contractile ring of cells...
2016: PloS One
https://www.readbyqxmd.com/read/27787439/damage-control-surgery-in-weightlessness-a-comparative-study-of-simulated-torso-hemorrhage-control-comparing-terrestrial-and-weightless-conditions
#12
Andrew W Kirkpatrick, Jessica Lynn McKee, Homer Tien, Anthony J LaPorta, Kit Lavell, Tim Leslie, David R King, Paul B McBeth, Susan Brien, Derek J Roberts, Reginald Franciose, Jonathan Wong, Vivian McAlistair, Danielle Bouchard, Chad G Ball
BACKGROUND: Torso bleeding remains the most preventable cause of post-traumatic death worldwide. Remote damage control resuscitation (RDCR) endeavours to rescue the most catastrophically injured, but has not focused on prehospital surgical torso hemorrhage control (HC). We examined the logistics and metrics of intraperitoneal packing in weightlessness in Parabolic flight (0g) compared to terrestrial gravity (1g) as an extreme example of surgical RDCR. METHODS: A surgical simulator was customized with high-fidelity intraperitoneal anatomy, a "blood" pump and flowmeter...
February 2017: Journal of Trauma and Acute Care Surgery
https://www.readbyqxmd.com/read/27623796/intramuscular-injection-of-mechano-growth-factor-e-domain-peptide-regulated-expression-of-memory-related-sod-mir-134-and-mir-125b-3p-in-rat-hippocampus-under-simulated-weightlessness
#13
Hailong Chen, Ke Lv, Zhongquan Dai, Guohua Ji, Tingmei Wang, Yanli Wang, Yongliang Zhang, Guanghan Kan, Yinghui Li, Lina Qu
OBJECTIVE: To investigate the expression of memory-related antioxidant genes and miRNAs under simulated weightlessness and the regulation of mechano growth factor (MGF) E domain, the peptide preventing nerve damage. RESULTS: Igf-iea and mgf mRNA levels, expression of antioxidant genes sod1 and sod2 and levels of miR-134 and miR-125b-3p increased in rat hippocampus after 14 days tail suspension to simulate weightlessness which was inhibited with intramuscular injection of E domain peptide...
December 2016: Biotechnology Letters
https://www.readbyqxmd.com/read/27581365/impact-of-simulated-microgravity-on-cytoskeleton-and-viscoelastic-properties-of-endothelial-cell
#14
M Janmaleki, M Pachenari, S M Seyedpour, R Shahghadami, A Sanati-Nezhad
This study focused on the effects of simulated microgravity (s-μg) on mechanical properties, major cytoskeleton biopolymers, and morphology of endothelial cells (ECs). The structural and functional integrity of ECs are vital to regulate vascular homeostasis and prevent atherosclerosis. Furthermore, these highly gravity sensitive cells play a key role in pathogenesis of many diseases. In this research, impacts of s-μg on mechanical behavior of human umbilical vein endothelial cells were investigated by utilizing a three-dimensional random positioning machine (3D-RPM)...
2016: Scientific Reports
https://www.readbyqxmd.com/read/27546500/systems-specificity-in-responsiveness-to-intermittent-artificial-gravity-during-simulated-microgravity-in-rats
#15
Li-Fan Zhang, Shu Zhang
It has been shown that the minimum gravity exposure requirements vary greatly among different physiological systems. A preliminary comparison between two extremes, vessels vs. bones, shows that not only the mechanostat at the tissue level differs greatly, but also the bone loss during weightlessness may also involve calcium deposition-resorption changes. It seems that the surprising efficacy of intermittent artificial gravity (IAG) is due to the vascular tissues possessing a strong resilience or "memory" function toward restoring their original pre-stress and tensegrity state at the 1 G environment...
August 25, 2016: Sheng Li Xue Bao: [Acta Physiologica Sinica]
https://www.readbyqxmd.com/read/27535987/to-crash-or-not-to-crash-how-do-hoverflies-cope-with-free-fall-situations-and-weightlessness
#16
Roman Goulard, Jean-Louis Vercher, Stéphane Viollet
Insects' aptitude to perform hovering, automatic landing and tracking tasks involves accurately controlling their head and body roll and pitch movements, but how this attitude control depends on an internal estimation of gravity orientation is still an open question. Gravity perception in flying insects has mainly been studied in terms of grounded animals' tactile orientation responses, but it has not yet been established whether hoverflies use gravity perception cues to detect a nearly weightless state at an early stage...
August 15, 2016: Journal of Experimental Biology
https://www.readbyqxmd.com/read/27516535/human-motor-control-of-landing-from-a-drop-in-simulated-microgravity
#17
Clément N Gambelli, Daniel Theisen, Patrick A Willems, Bénédicte Schepens
Landing on the ground on one's feet implies that the energy gained during the fall be dissipated. The aim of this study is to assess human motor control of landing in different conditions of fall initiation, simulated gravity and sensory neural input. Six participants performed drop-landings using a trap-door system and landings from self-initiated counter-movement jumps in microgravity conditions, simulated in a weightlessness environment by different pull-down forces, of 1-, 0.6-, 0.4- and 0.2 g. External forces applied to the body, orientation of the lower limb segments and muscular activity of 6 lower limb muscles were recorded synchronously...
August 11, 2016: Journal of Applied Physiology
https://www.readbyqxmd.com/read/27467019/apollo-lunar-astronauts-show-higher-cardiovascular-disease-mortality-possible-deep-space-radiation-effects-on-the-vascular-endothelium
#18
Michael D Delp, Jacqueline M Charvat, Charles L Limoli, Ruth K Globus, Payal Ghosh
As multiple spacefaring nations contemplate extended manned missions to Mars and the Moon, health risks could be elevated as travel goes beyond the Earth's protective magnetosphere into the more intense deep space radiation environment. The primary purpose of this study was to determine whether mortality rates due to cardiovascular disease (CVD), cancer, accidents and all other causes of death differ in (1) astronauts who never flew orbital missions in space, (2) astronauts who flew only in low Earth orbit (LEO), and (3) Apollo lunar astronauts, the only humans to have traveled beyond Earth's magnetosphere...
July 28, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27366682/effect-of-long-term-weightlessness-on-retina-and-optic-nerve-in-tail-suspension-rats
#19
Hong-Wei Zhao, Jun Zhao, Lian-Na Hu, Jing-Nan Liang, Yuan-Yuan Shi, Chuang Nie, Chang-Yu Qiu, Xin-Shuai Nan, Yu-Xin Li, Fu-Lin Gao, Yi Liu, Yu Dong, Ling Luo
AIM: To evaluate the effect of long-term weightlessness on retina and optic nerve in tail-suspension (TS) rats. METHODS: A stimulated weightlessness model was established by suspending rats' tail. After 12wk, the ultrastructure and the number of optic nerve axons were observed by transmission electron microscope. The number of survival retinal ganglion cells (RGCs) was calculated by fluorescent gold retrograde labeling. Retina cells apoptosis was detected by TUNEL staining...
2016: International Journal of Ophthalmology
https://www.readbyqxmd.com/read/27352896/influence-of-body-weight-on-bone-mass-architecture-and-turnover
#20
REVIEW
Urszula T Iwaniec, Russell T Turner
Weight-dependent loading of the skeleton plays an important role in establishing and maintaining bone mass and strength. This review focuses on mechanical signaling induced by body weight as an essential mechanism for maintaining bone health. In addition, the skeletal effects of deviation from normal weight are discussed. The magnitude of mechanical strain experienced by bone during normal activities is remarkably similar among vertebrates, regardless of size, supporting the existence of a conserved regulatory mechanism, or mechanostat, that senses mechanical strain...
September 2016: Journal of Endocrinology
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