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https://www.readbyqxmd.com/read/28649624/spaceflight-induced-neuroplasticity-in-humans-as-measured-by-mri-what-do-we-know-so-far
#1
Angelique Van Ombergen, Steven Laureys, Stefan Sunaert, Elena Tomilovskaya, Paul M Parizel, Floris L Wuyts
Space travel poses an enormous challenge on the human body; microgravity, ionizing radiation, absence of circadian rhythm, confinement and isolation are just some of the features associated with it. Obviously, all of the latter can have an impact on human physiology and even induce detrimental changes. Some organ systems have been studied thoroughly under space conditions, however, not much is known on the functional and morphological effects of spaceflight on the human central nervous system. Previous studies have already shown that central nervous system changes occur during and after spaceflight in the form of neurovestibular problems, alterations in cognitive function and sensory perception, cephalic fluid shifts and psychological disturbances...
2017: NPJ Microgravity
https://www.readbyqxmd.com/read/28646228/coronal-mass-ejections-are-not-coherent-magnetohydrodynamic-structures
#2
M J Owens, M Lockwood, L A Barnard
Coronal mass ejections (CMEs) are episodic eruptions of solar plasma and magnetic flux that travel out through the solar system, driving extreme space weather. Interpretation of CME observations and their interaction with the solar wind typically assumes CMEs are coherent, almost solid-like objects. We show that supersonic radial propagation of CMEs away from the Sun results in geometric expansion of CME plasma parcels at a speed faster than the local wave speed. Thus information cannot propagate across the CME...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28640618/dynamic-roughness-ratio-based-framework-for-modeling-mixed-mode-of-droplet-evaporation
#3
Madhu Ranjan Gunjan, Rishi Raj
The spatio-temporal evolution of an evaporating sessile droplet and its effect on lifetime is crucial to various disciplines of science and technology. While experimental investigations suggest three distinct modes through which a droplet evaporates, namely, the constant contact radius (CCR), the constant contact angle (CCA), and the mixed, only the CCR and the CCA modes have been modeled reasonably. Here we use experiments with water droplets on flat and micropillared silicon substrates to characterize the mixed mode...
June 22, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28626276/standing-and-travelling-waves-in-a-spherical-brain-model-the-nunez-model-revisited
#4
S Visser, R Nicks, O Faugeras, S Coombes
The Nunez model for the generation of electroencephalogram (EEG) signals is naturally described as a neural field model on a sphere with space-dependent delays. For simplicity, dynamical realisations of this model either as a damped wave equation or an integro-differential equation, have typically been studied in idealised one dimensional or planar settings. Here we revisit the original Nunez model to specifically address the role of spherical topology on spatio-temporal pattern generation. We do this using a mixture of Turing instability analysis, symmetric bifurcation theory, centre manifold reduction and direct simulations with a bespoke numerical scheme...
June 15, 2017: Physica D. Nonlinear Phenomena
https://www.readbyqxmd.com/read/28624709/contracted-time-and-expanded-space-the-impact-of-circumnavigation-on-judgements-of-space-and-time
#5
Iva K Brunec, Amir-Homayoun Javadi, Fiona E L Zisch, Hugo J Spiers
The ability to estimate distance and time to spatial goals is fundamental for survival. In cases where a region of space must be navigated around to reach a location (circumnavigation), the distance along the path is greater than the straight-line Euclidean distance. To explore how such circumnavigation impacts on estimates of distance and time, we tested participants on their ability to estimate travel time and Euclidean distance to learned destinations in a virtual town. Estimates for approximately linear routes were compared with estimates for routes requiring circumnavigation...
June 15, 2017: Cognition
https://www.readbyqxmd.com/read/28619408/children-crossing-streets-the-cognitive-task-of-pedestrians-across-nations
#6
David C Schwebel
BACKGROUND: About 100,000 children die worldwide in pedestrian crashes, more than 90% of whom live in low- and middle-income countries (LMICs). However, most existing research on children's ability to cross the street is conducted in high-income countries (HICs). OBJECTIVE: The present study discusses 4 ways pedestrian behavior in LMICs differs from that in HICs, influencing both children's ability to cross streets safely and adult efforts to train children in pedestrian safety...
March 2017: Annals of Global Health
https://www.readbyqxmd.com/read/28617345/examining-associations-of-environmental-characteristics-with-recreational-cycling-behaviour-by-street-level-strava-data
#7
Yeran Sun, Yunyan Du, Yu Wang, Liyuan Zhuang
Policymakers pay much attention to effectively increasing frequency of people's cycling in the context of developing sustainable and green cities. Investigating associations of environmental characteristics and cycling behaviour could offer implications for changing urban infrastructure aiming at encouraging active travel. However, earlier examinations of associations between environmental characteristics and active travel behaviour are limited by low spatial granularity and coverage of traditional data. Crowdsourced geographic information offers an opportunity to determine the fine-grained travel patterns of people...
June 15, 2017: International Journal of Environmental Research and Public Health
https://www.readbyqxmd.com/read/28616247/planarian-regeneration-in-space-persistent-anatomical-behavioral-and-bacteriological-changes-induced-by-space-travel
#8
Junji Morokuma, Fallon Durant, Katherine B Williams, Joshua M Finkelstein, Douglas J Blackiston, Twyman Clements, David W Reed, Michael Roberts, Mahendra Jain, Kris Kimel, Sunia A Trauger, Benjamin E Wolfe, Michael Levin
Regeneration is regulated not only by chemical signals but also by physical processes, such as bioelectric gradients. How these may change in the absence of the normal gravitational and geomagnetic fields is largely unknown. Planarian flatworms were moved to the International Space Station for 5 weeks, immediately after removing their heads and tails. A control group in spring water remained on Earth. No manipulation of the planaria occurred while they were in orbit, and space-exposed worms were returned to our laboratory for analysis...
April 2017: Regeneration
https://www.readbyqxmd.com/read/28613990/different-sequences-of-fractionated-low-dose-proton-and-single-iron-radiation-induced-divergent-biological-responses-in-the-heart
#9
Sharath P Sasi, Xinhua Yan, Marian Zuriaga-Herrero, Hannah Gee, Juyong Lee, Raman Mehrzad, Jin Song, Jillian Onufrak, James Morgan, Heiko Enderling, Kenneth Walsh, Raj Kishore, David A Goukassian
Deep-space travel presents risks of exposure to ionizing radiation composed of a spectrum of low-fluence protons ((1)H) and high-charge and energy (HZE) iron nuclei (e.g., (56)Fe). When exposed to galactic cosmic rays, each cell in the body may be traversed by (1)H every 3-4 days and HZE nuclei every 3-4 months. The effects of low-dose sequential fractionated (1)H or HZE on the heart are unknown. In this animal model of simulated ionizing radiation, middle-aged (8-9 months old) male C57BL/6NT mice were exposed to radiation as follows: group 1, nonirradiated controls; group 2, three fractionated doses of 17 cGy (1)H every other day ((1)H × 3); group 3, three fractionated doses of 17 cGy (1)H every other day followed by a single low dose of 15 cGy (56)Fe two days after the final (1)H dose ((1)H × 3 + (56)Fe); and group 4, a single low dose of 15 cGy (56)Fe followed (after 2 days) by three fractionated doses of 17 cGy (1)H every other day ((56)Fe + (1)H × 3)...
June 14, 2017: Radiation Research
https://www.readbyqxmd.com/read/28608230/acknowledging-crossing-avoidance-heuristic-violations-when-solving-the-euclidean-travelling-salesperson-problem
#10
Markos Kyritsis, Stephen R Gulliver, Eva Feredoes
If a salesperson aims to visit a number of cities only once before returning home, which route should they take to minimise the total distance/cost? This combinatorial optimization problem is called the travelling salesperson problem (TSP) and has a rapid growth in the number of possible solutions as the number of cities increases. Despite its complexity, when cities and routes are represented in 2D Euclidean space (ETSP), humans solve the problem with relative ease, by applying simple visual heuristics. One of the most important heuristics appears to be the avoidance of path crossings, which will always result in more optimal solutions than tours that contain crossings...
June 12, 2017: Psychological Research
https://www.readbyqxmd.com/read/28590759/effects-of-nozzle-geometry-on-the-fluid-dynamics-of-thin-liquid-films-flowing-down-vertical-strings-in-the-rayleigh-plateau-regime
#11
Abolfazl Sadeghpour, Zezhi Zeng, Y Sungtaek Ju
Thin-liquid films flowing down vertical strings undergo instability, creating wavy film profiles and traveling beads. Previous studies assumed that the liquid film thickness and velocity profiles within the healing length from a nozzle were specified by the Nusselt solution, independent of the nozzle geometry. As a result, the influence of the nozzle diameter on the flow characteristics, such as the liquid bead size, spacing, and traveling speed, was largely overlooked. We report an experimental and numerical simulation study on liquid-film flows in the Rayleigh-Plateau regime while systematically varying the nozzle diameter from 0...
June 15, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28581292/photoinitiated-dynamics-in-amorphous-solid-water-via-nanoimprint-lithography
#12
Christopher Larson, Yuanrui Li, Wei Wu, Hanna Reisler, Curt Wittig
Laser pulses that act on fragile samples often alter them irreversibly, motivating single-pulse data collection. Amorphous solid water (ASW) is a good example. In addition, neither well-defined paths for molecules to travel through ASW nor sufficiently small samples to enable molecular dynamics modeling have been achieved. Combining nanoimprint lithography and photoinitiation overcomes these obstacles. An array of gold nanoparticles absorbs pulsed (10 ns) 532 nm radiation and converts it to heat, and doped ASW films grown at about 100 K are ejected from atop the irradiated nanoparticles into vacuum...
June 21, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28571468/radar-for-tracer-particles
#13
Felix Ott, Stephan Herminghaus, Kai Huang
We introduce a radar system capable of tracking a 5 mm spherical target continuously in three dimensions. The 10 GHz (X-band) radar system has a transmission power of 1 W and operates in the near field of the horn antennae. By comparing the phase shift of the electromagnetic wave traveling through the free space with an IQ-mixer, we obtain the relative movement of the target with respect to the antennae. From the azimuth and inclination angles of the receiving antennae obtained in the calibration, we reconstruct the target trajectory in a three-dimensional Cartesian system...
May 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28528904/spatially-periodic-activation-patterns-of-retrosplenial-cortex-encode-route-sub-spaces-and-distance-traveled
#14
Andrew S Alexander, Douglas A Nitz
Traversal of a complicated route is often facilitated by considering it as a set of related sub-spaces. Such compartmentalization processes could occur within retrosplenial cortex, a structure whose neurons simultaneously encode position within routes and other spatial coordinate systems. Here, retrosplenial cortex neurons were recorded as rats traversed a track having recurrent structure at multiple scales. Consistent with a major role in compartmentalization of complex routes, individual retrosplenial cortex (RSC) neurons exhibited periodic activation patterns that repeated across route segments having the same shape...
June 5, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28528322/very-low-doses-of-heavy-oxygen-ion-radiation-induce-premature-ovarian-failure
#15
Birendra Mishra, Ryan Ripperdan, Laura Ortiz, Ulrike Luderer
Astronauts are exposed to charged particles during space travel, and charged particles are also used for cancer radiotherapy. Premature ovarian failure is a well-known side effect of conventional, low linear energy transfer (LET) cancer radiotherapy, but little is known about the effects of high LET charged particles on the ovary. We hypothesized that lower LET (16.5 keV/µm) oxygen particles would be less damaging to the ovary than we previously found for iron (LET = 179 keV/µm). Adult female mice were irradiated with 0, 5, 30 or 50 cGy oxygen ions or 50 cGy oxygen plus dietary supplementation with the antioxidant alpha lipoic acid (ALA)...
August 2017: Reproduction: the Official Journal of the Society for the Study of Fertility
https://www.readbyqxmd.com/read/28527648/a-case-of-amebiasis-with-negative-serologic-markers-that-caused-intra-abdominal-abscess
#16
Rie Tanaka, Norihiro Furusyo, Rinne Takeda, Sho Yamasaki, Akira Kusaga, Eiichi Ogawa, Masayuki Murata, Ryota Nakanishi, Yoshihiko Maehara
A 23-year-old Japanese woman presented with abdominal distention following fever, diarrhea, and abdominal pain during a stay in Taiwan. Serology for the detection of amebic-antibodies and stool microscopic examination were both negative. A computed tomography scan showed a 13 cm diameter abscess spreading from the lower abdominal wall to the pelvic retroperitoneal space. Needle aspiration of the abscess was done under computed tomography guidance, and microscopy of the aspirated fluid revealed trophozoites of Entamoeba...
May 17, 2017: Journal of Infection and Chemotherapy: Official Journal of the Japan Society of Chemotherapy
https://www.readbyqxmd.com/read/28511081/a-novel-ultrasonic-surface-machining-tool-utilizing-elastic-traveling-waves
#17
Ruinan Ji, Jiamei Jin, Liang Wang, Jianhui Zhang
With the rapid development of modern industrial technology and high performance technology products, ultra-precision machining technology becomes increasingly important. However, joint clearance of kinematic pairs, lack of feeding accuracy and overlarge contact stress still limit the further improvement of ultra-precision machining technology. In this study, a novel surface machining method utilizing structural elastic waves was proposed, and a machining tool using the piezoelectric actuating principle was presented for verifying the proposed method...
September 2017: Ultrasonics
https://www.readbyqxmd.com/read/28505846/traveling-waves-and-worms-in-ac-driven-electroconvection-under-external-multiplicative-noise
#18
Jong-Hoon Huh
In the presence of external multiplicative noise, ac-driven electroconvection (EC) in a nematic liquid crystal is investigated. Noise-induced traveling waves (TWs) including localized ones (worms) are found with a typical, stationary wave. Three kinds of TWs are classified by their dynamic features (e.g., noise-intensity-dependent Hopf frequency and space-time map). Moreover, ac frequency-dependent threshold voltages of EC are examined in high noise intensities causing abnormal charge redistribution of the EC cell, and the roles of ac and noise fields with respect to TWs are elucidated in successive pattern evolutions...
April 2017: Physical Review. E
https://www.readbyqxmd.com/read/28505829/control-of-amplitude-chimeras-by-time-delay-in-oscillator-networks
#19
Aleksandar Gjurchinovski, Eckehard Schöll, Anna Zakharova
We investigate the influence of time-delayed coupling in a ring network of nonlocally coupled Stuart-Landau oscillators upon chimera states, i.e., space-time patterns with coexisting partially coherent and partially incoherent domains. We focus on amplitude chimeras, which exhibit incoherent behavior with respect to the amplitude rather than the phase and are transient patterns, and we show that their lifetime can be significantly enhanced by coupling delay. To characterize their transition to phase-lag synchronization (coherent traveling waves) and other coherent structures, we generalize the Kuramoto order parameter...
April 2017: Physical Review. E
https://www.readbyqxmd.com/read/28505805/hysteresis-in-relative-permeabilities-suffices-for-propagation-of-saturation-overshoot-a-quantitative-comparison-with-experiment
#20
R Steinle, R Hilfer
Traditional Darcy theory for two-phase flow in porous media is shown to predict the propagation of nonmonotone saturation profiles, also known as saturation overshoot. The phenomenon depends sensitively on the constitutive parameters, on initial conditions, and on boundary conditions. Hysteresis in relative permeabilities is needed to observe the effect. Two hysteresis models are discussed and compared. The shape of overshoot solutions can change as a function of time or remain fixed and time independent. Traveling-wave-like overshoot profiles of fixed width exist in experimentally accessible regions of parameter space...
April 2017: Physical Review. E
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