Models to study gravitational biology of Mammalian reproduction

NASA Technical Reports Server (NTRS)

Tou, Janet; Ronca, April; Grindeland, Richard; Wade, Charles

2002-01-01

Mammalian reproduction evolved within Earth's 1-g gravitational field. As we move closer to the reality of space habitation, there is growing scientific interest in how different gravitational states influence reproduction in mammals. Habitation of space and extended spaceflight missions require prolonged exposure to decreased gravity (hypogravity, i.e., weightlessness). Lift-off and re-entry of the spacecraft are associated with exposure to increased gravity (hypergravity). Existing data suggest that spaceflight is associated with a constellation of changes in reproductive physiology and function. However, limited spaceflight opportunities and confounding effects of various nongravitational factors associated with spaceflight (i.e., radiation, stress) have led to the development of ground-based models for studying the effects of altered gravity on biological systems. Human bed rest and rodent hindlimb unloading paradigms are used to study exposure to hypogravity. Centrifugation is used to study hypergravity. Here, we review the results of spaceflight and ground-based models of altered gravity on reproductive physiology. Studies utilizing ground-based models that simulate hyper- and hypogravity have produced reproductive results similar to those obtained from spaceflight and are contributing new information on biological responses across the gravity continuum, thereby confirming the appropriateness of these models for studying reproductive responses to altered gravity and the underlying mechanisms of these responses. Together, these unique tools are yielding new insights into the gravitational biology of reproduction in mammals.

Cardiovascular and organ responses and adaptation responses to hypogravity in an experimental animal model.

NASA Astrophysics Data System (ADS)

Biondi, R.; Capodicasa, E.; Tassi, C.; Mezzasomal, L.; Benedetti, C.; Valiani, M.; Marconi, P.; Rossi, R.

1995-10-01

The head-down suspension (i.e antiorthostatic hypokinesia) rat is used to simulate weightlessness. However, little is known about cardiovascular and organ adaptation responses which, over a long time, can become pathologically significant. The purpose of this study was therefore to evaluate regional changes in the hematology parameters, Endotheline-1 (ET-1) concentration and urinary excretion of N-acetyl-β-D-glucosaminidase (EC 3.2.1.30) (NAG) in an experimental antiorthostatic rat model. The data indicate significant variations in the plasma ET-1 level in time, in the superior and inferior cava vessel blood of animals maintained for 10 days in hypogravity with respect to controls. These changes do not seem to be due to hemoconcentration. The increase in urinary NAG was observed during the first 24h of experiment, indicating renal stress, probably due to adverse blood flow variations within the organ. We conclude that the plasma ET-1 level changes could be responsible, overall for the blood flow variations in the kidney and renal stress could be the consequence of extended antiorthostatic hypokinesia. The ET-1 behaviour and urinary NAG excretion in rats exposed to antiorthostatic hypokjnetic hydynamia offer possibilities for understanding if these changes might be reversible or when they become pathological. This could give some relevant information about the effects of prolonged hypogravity during the space voyage.

Morphometric analysis of rat muscle fibers following space flight and hypogravity

NASA Technical Reports Server (NTRS)

Chui, L. A.; Castleman, K. R.

1982-01-01

The effect of hypogravity on striate muscles, containing both fast twitch glycolytic and slow twitch oxidative fibers, was studied in rats aboard two Cosmos biosatellites. Results of a computer-assisted image analysis of extensor digitorum muscles from five rats, exposed to 18.5 days of hypogravity and processed for the alkaline ATPase reaction, showed a reduction of the mean fiber diameter (41.32 + or - 0.55 microns), compared to synchronous (46.32 + or - 0.55 microns) and vivarium (49 + or - 0.5 microns) controls. A further experiment studied the ratio of fast to slow twitch fibers in 25 rats exposed to 18.5 days of hypogravity and analyzed at four different periods of recovery following the space flight. Using the previous techniques, the gastrocnemius muscle showed a reduction of the total muscle fiber area in square microns and a reduction in the percentage of slow fibers of flight animals compared to the control animals.

A Case for Hypogravity Studies Aboard ISS

NASA Technical Reports Server (NTRS)

Paloski, William H.

2014-01-01

Future human space exploration missions being contemplated by NASA and other spacefaring nations include some that would require long stays upon bodies having gravity levels much lower than that of Earth. While we have been able to quantify the physiological effects of sustained exposure to microgravity during various spaceflight programs over the past half-century, there has been no opportunity to study the physiological adaptations to gravity levels between zero-g and one-g. We know now that the microgravity environment of spaceflight drives adaptive responses of the bone, muscle, cardiovascular, and sensorimotor systems, causing bone demineralization, muscle atrophy, reduced aerobic capacity, motion sickness, and malcoordination. All of these outcomes can affect crew health and performance, particularly after return to a one-g environment. An important question for physicians, scientists, and mission designers planning human exploration missions to Mars (3/8 g), the Moon (1/6 g), or asteroids (likely negligible g) is: What protection can be expected from gravitational levels between zero-g and one-g? Will crewmembers deconditioned by six months of microgravity exposure on their way to Mars experience continued deconditioning on the Martian surface? Or, will the 3/8 g be sufficient to arrest or even reverse these adaptive changes? The implications for countermeasure deployment, habitat accommodations, and mission design warrant further investigation into the physiological responses to hypogravity. It is not possible to fully simulate hypogravity exposure on Earth for other than transient episodes (e.g., parabolic flight). However, it would be possible to do so in low Earth orbit (LEO) using the centrifugal forces produced in a live-aboard centrifuge. As we're not likely to launch a rotating human spacecraft into LEO anytime in the near future, we could take advantage of rodent subjects aboard the ISS if we had a centrifuge that could accommodate the rodent subjects for extended periods (weeks to months) at various hypogravity levels. Experiments aboard such a centrifuge could provide important insight into human exploration questions and simultaneously answer fundamental questions in gravitational physiology.

Cardiovascular responses to hypogravic environments

NASA Technical Reports Server (NTRS)

Sandler, H.

1983-01-01

The cardiovascular deconditioning observed during and after space flight is characterized in a review of human space and simulation studies and animal simulations. The various simulation techniques (horizontal bed rest, head-down tilt, and water immersion in man, and immobilization of animals) are examined, and sample results are presented in graphs. Countermeasures such as exercise regimens, fluid replacement, drugs, venous pooling, G-suits, oscillating beds, electrostimulation of muscles, lower-body negative pressure, body-surface cooling, and hypoxia are reviewed and found to be generally ineffective or unreliable. The need for future space experimentation in both humans and animals is indicated.

Issues on human acceleration tolerance after long-duration space flights

NASA Technical Reports Server (NTRS)

Kumar, K. Vasantha; Norfleet, William T.

1992-01-01

This report reviewed the literature on human tolerance to acceleration at 1 G and changes in tolerance after exposure to hypogravic fields. It was found that human tolerance decreased after exposure to hypokinetic and hypogravic fields, but the magnitude of such reduction ranged from 0 to 30 percent for plateau G forces and 30 to 70 percent for time tolerance on sustained G forces. A logistic regression model of the probability of individuals with 25 percent reduction in +Gz tolerance after 1 to 41 days of hypogravic exposures was constructed. The estimated values from the model showed a good correlation with the observed data. A brief review of the need for in-flight centrifuge during long-duration missions was also presented. Review of the available data showed that the use of countermeasures (such as anti-G suits, periodic acceleration, and exercise) reduced the decrement in acceleration tolerance after long-duration space flights. Areas of further research include quantification of the effect of countermeasures on tolerance, and methods to augment tolerance during and after exposures to hypogravic fields. Such data are essential for planning long-duration human missions.

Simulated hypogravity and synaptogenesis in culture

NASA Technical Reports Server (NTRS)

Gruener, R.

1985-01-01

A study on the effects of simulated microgravity on spinal neurons and myocytes cultured from X. laevis, is performed. Horizontal clinorotation at 1-10 rpm lasted from 16-36 hours, a sufficient time for cells to proceed through ontogenetic maturation. Late appearance of striations, retarded consumpton of yolk platelets and fewer and thinner neurites indicate subnormal expression of cell functions. Furthermore, these cells do not respond normally to environmental cues like trophic substances or surface contact. The observed delay in cell maturation is consistent with a hypothesis that cellular graviperception may effect the centriole and cytoskeleton.

Our experience in the evaluation of the thermal comfort during the space flight and in the simulated space environment

NASA Astrophysics Data System (ADS)

Novák, Ludvik

The paper presents the results of the mathematical modelling the effects of hypogravity on the heat output by the spontaneous convection. The theoretical considerations were completed by the experiments "HEAT EXCHANGE 1" performed on the biosatellite "KOSMOS 936". In the second experiment "HEAT EXCHANGE 2" acomplished on the board of the space laboratory "SALYUT 6" was studied the effect of the microgravity on the thermal state of a man during the space flight. Direct measurement in weightlessness prowed the capacity of the developed electric dynamic katathermometer to check directly the effect of the microgravity on the heat output by the spontaneous convection. The role of the heat partition impairment's in man as by the microgravity, so by the inadequate forced convection are clearly expressed in changes of the skin temperature and the subjective feeling of the cosmonaut's thermal comfort. The experimental extension of the elaborated methods for the flexible adjustment of the thermal environment to the actual physiological needs of man and suggestions for the further investigation are outlined.

Metabolism and biochemistry in hypogravity

NASA Technical Reports Server (NTRS)

Leach, Carolyn S.

1991-01-01

The headward shift of body fluid and increase in stress-related hormones that occur in hypogravity bring about a number of changes in metabolism and biochemistry of the human body. Such alterations may have important effects on health during flight and during a recovery period after return to earth. Body fluid and electrolytes are lost, and blood levels of several hormones that control metabolism are altered during space flight. Increased serum calcium may lead to an increased risk of renal stone formation during flight, and altered drug metabolism could influence the efficacy of therapeutic agents. Orthostatic intolerance and an increased risk of fracturing weakened bones are concerns at landing. It is important to understand biochemistry and metabolism in hypogravity so that clinically important developments can be anticipated and prevented or ameliorated.

Life Sciences Research and Development Opportunities During Suborbital Space Flight

NASA Technical Reports Server (NTRS)

Davis, Jeffrey R.

2010-01-01

Suborbital space platforms provide a unique opportunity for Space Life Sciences in the next few years. The opportunities include: physiological characterization of the first few minutes of space flight; evaluation of a wide-variety of medical conditions during periods of hyper and hypo-gravity through physiological monitoring; and evaluation of new biomedical and environmental health technologies under hyper and hypo-gravity conditions

Simulating certain aspects of hypogravity - Effects on bone maturation in the nonweight bearing skeleton

NASA Technical Reports Server (NTRS)

Simmons, D. J.; Grazman, B.; Russell, J. E.; Walker, W. V.; Bikle, D. D.; Morey, E. R.

1983-01-01

For a determination of how the nonweight-bearing skeletons, i.e., lower jaws, of 41-day and 1-year old rats would respond to 10 or 14 days of partial skeletal unloading by elevating the hindquarters (PULEH), an experimental system to simulate the fluid shifts and unloading of portions of the skeleton which occur during spaceflight was developed. In comparison with the bone matrix mineralization recorded in the mandibles of rats flown in the Soviet 18.5 day Cosmos-1129 mission, the PULEH studies failed to produce spaceflight-like maturation defects.

Effects of diet and exposure to hindlimb suspension on estrous cycling in Sprague-Dawley rats

NASA Technical Reports Server (NTRS)

Tou, Janet C L.; Grindeland, Richard E.; Wade, Charles E.

2004-01-01

Various factors can disrupt the female reproductive cycle resulting in subfertility. The primary objective of this study was to determine whether physiological changes associated with exposure to hypogravity disrupt reproductive cycles. The hindlimb suspension (HLS) model was used to simulate the major physiological effects of hypogravity in female Sprague-Dawley rats. Also, to determine whether diet may influence reproductive results, rats were fed purified American Institute of Nutrition (AIN)-93G or chow diet. Rats (n = 9-11/group) subjected to HLS had lengthened estrous cycles due to prolonged diestrus, indicating hypoestrogenism. Interestingly, HLS rats fed AIN-93G but not chow diet had significantly reduced time spent in estrus and decreased plasma estradiol. Attenuation of hypoestrogenism in the chow-fed rats suggested that diet provided an exogenous source of estrogen. The mechanism involved in the disruption of estrous cycling remains to be determined. HLS increased urinary corticosterone (CORT) levels during the initial 4 days of HLS, suggesting that physiological responses to acute stress may be a potential mechanism in the disruption of estrous cycles. Higher basal urinary CORT was observed in rats fed chow vs. AIN-93G diet. HLS resulted in increased urinary CORT. However, two-way ANOVA indicated a significant HLS effect (P < 0.001) but no effect of HLS x diet effect on urinary CORT levels, suggesting that estrogenic activity associated with the chow diet did not enhance the stress response. The results of this study indicate that HLS, diet, and the combination of HLS and diet influence estrous cycling. This has important implications for future reproductive success in the hypogravity environment of space.

Hypogravity-induced atrophy of rat soleus and extensor digitorum longus muscles

NASA Technical Reports Server (NTRS)

Riley, D. A.; Ellis, S.; Slocum, G. R.; Satyanarayana, T.; Bain, J. L.; Sedlak, F. R.

1987-01-01

Prolonged exposure of humans to hypogravity causes weakening of their skeletal muscles. This problem was studied in rats exposed to hypogravity for 7 days aboard Spacelab 3. Hindlimb muscles were harvested 12-16 hours postflight for histochemical, biochemical, and ultrastructural analyses. The majority of the soleus and extensor digitorum longus fibers exhibited simple cell shrinkage. However, approximately 1% of the fibers in flight soleus muscles appeared necrotic. Flight muscle fibers showed increased glycogen, lower subsarcolemmal staining for mitochondrial enzymes, and fewer subsarcolemmal mitochondria. During atrophy, myofibrils were eroded by multiple focal losses of myofilaments; lysosomal autophagy was not evident. Tripeptidylaminopeptidase and calcium-activated protease activities of flight soleus fibers were significantly increased, implying a role in myofibril breakdown. Simple fiber atrophy appears to account for muscle weakening during spaceflight, but fiber necrosis is also a contributing factor.

Microgravity and Hypogravity Compatible Methods for the Destruction of Solid Wastes by Magnetically Assisted Gasification

NASA Technical Reports Server (NTRS)

Atwater, James E.; Akse, James R.; Wheeler, Richard R., Jr.; Jovanovic, Goran N.; Pinto-Espinoza, Joaquin; Reed, Brian; Sornchamni, Thana

2003-01-01

This report summarizes a three-year collaborative effort between researchers at UMPQUA Research Company (URC) and the Chemical Engineering Department at Oregon State University (OSU). The Magnetically Assisted Gasification (MAG) concept was originally conceived as a microgravity and hypogravity compatible means for the decomposition of solid waste materials generated aboard spacecraft, lunar and planetary habitations, and for the recovery of potentially valuable resources. While a number of methods such as supercritical water oxidation (SCW0), fluidized bed incineration, pyrolysis , composting and related biological processes have been demonstrated for the decomposition of solid wastes, none of these methods are particularly well- suited for employment under microgravity or hypogravity conditions. For example, fluidized bed incineration relies upon a balance between drag forces which the flowing gas stream exerts upon the fluidization particles and the opposing force of gravity. In the absence of gravity, conventional fluidization cannot take place. Hypogravity operation can also be problematic for conventional fluidized bed reactors, because the various factors which govern fluidization phenomena do not all scale linearly with gravity. For this reason it may be difficult to design and test fluidized bed reactors in lg, which are intended to operate under different gravitational conditions. However, fluidization can be achieved in microgravity (and hypogravity) if a suitable replacement force to counteract the forces between fluid and particles can be found. Possible alternatives include: centripetal force, electric fields, or magnetic fields. Of these, magnetic forces created by the action of magnetic fields and magnetic field gradients upon ferromagnetic media offer the most practical approach. The goal of this URC-OSU collaborative effort was to develop magnetic hardware and methods to control the degree of fluidization (or conversely consolidation) of granular ferromagnetic media and to employ these innovations in sequential filtration and fluidized bed processes for the segregation and decomposition of solid waste materials, and for the concentration and collection of inorganic residue (ash). This required the development of numerous enabling technologies and tools.

Growth and development of cultured carrot cells and embryos under spaceflight conditions

NASA Technical Reports Server (NTRS)

Krikorian, A. D.; Dutcher, F. R.; Quinn, C. E.; Steward, F. C.

1981-01-01

Morphogenetically competent proembryonic cells and well-developed somatic embryos of carrot at two levels of organization were exposed for 18.5 days to a hypogravity environment aboard the Soviet Biosatellite Cosmos 1129. It was confirmed that cultured totipotent cells of carrot can give rise to embryos with well-developed roots and minimally developed shoots. It was also shown that the space hypogravity environment could support the further growth of already-organized, later somatic embryonic stages and give rise to fully developed embryo-plantlets with roots and shoots.

Modeling human perception of orientation in altered gravity

PubMed Central

Clark, Torin K.; Newman, Michael C.; Oman, Charles M.; Merfeld, Daniel M.; Young, Laurence R.

2015-01-01

Altered gravity environments, such as those experienced by astronauts, impact spatial orientation perception, and can lead to spatial disorientation and sensorimotor impairment. To more fully understand and quantify the impact of altered gravity on orientation perception, several mathematical models have been proposed. The utricular shear, tangent, and the idiotropic vector models aim to predict static perception of tilt in hyper-gravity. Predictions from these prior models are compared to the available data, but are found to systematically err from the perceptions experimentally observed. Alternatively, we propose a modified utricular shear model for static tilt perception in hyper-gravity. Previous dynamic models of vestibular function and orientation perception are limited to 1 G. Specifically, they fail to predict the characteristic overestimation of roll tilt observed in hyper-gravity environments. To address this, we have proposed a modification to a previous observer-type canal-otolith interaction model based upon the hypothesis that the central nervous system (CNS) treats otolith stimulation in the utricular plane differently than stimulation out of the utricular plane. Here we evaluate our modified utricular shear and modified observer models in four altered gravity motion paradigms: (a) static roll tilt in hyper-gravity, (b) static pitch tilt in hyper-gravity, (c) static roll tilt in hypo-gravity, and (d) static pitch tilt in hypo-gravity. The modified models match available data in each of the conditions considered. Our static modified utricular shear model and dynamic modified observer model may be used to help quantitatively predict astronaut perception of orientation in altered gravity environments. PMID:25999822

A novel variable-gravity simulation method: potential for astronaut training.

PubMed

Sussingham, J C; Cocks, F H

1995-11-01

Zero gravity conditions for astronaut training have traditionally used neutral buoyancy tanks, and with such tanks hypogravity conditions are produced by the use of supplemental weights. This technique does not allow for the influence of water viscosity on any reduced gravity exercise regime. With a water-foam fluid produced by using a microbubble air flow together with surface active agents to prevent bubble agglomeration, it has been found possible to simulate a range of gravity conditions without the need for supplemental weights and additionally with a substantial reduction in the resulting fluid viscosity. This new technique appears to have application in improving the simulation environment for astronaut training under the reduced gravity conditions to be found on the moon or on Mars, and may have terrestrial applications in patient rehabilitation and exercise as well.

The behavior of renal-regulating hormones during hypogravic stress

NASA Technical Reports Server (NTRS)

Leonard, J. I.

1985-01-01

The regulation of fluid and electrolyte behavior during space flight is believed to be under control, in large part, of a group of hormones which have their major effects on renal excretion. The hormones studied include renin-angitensin, aldosterone, and antidiuretic hormone (ADH). The regulatory systems of these renal-regulating hormones as they act individually and in concert with each other are analyzed. The analysis is based on simulations of the mathematical model of Guyton. A generalized theory is described which accounts for both short-term and long-term behavior of this set of hormones.

Cardiovascular responses to repetitive exposure to hyper- and hypogravity states produced by parabolic flight.

PubMed

Mukai, C N; Lathers, C M; Charles, J B; Bennett, B S

1994-05-01

Physiologic changes to repetitive hyper- and hypogravity stresses occurring during eight to ten parabolas on NASA's KC-135 aircraft were studied. Hemodynamic responses in 11 subjects in 4 different postures (supine, standing, sitting, and semisupine Space Shuttle launch position) were determined using noninvasive impedance cardiography. Five seconds of heart rate, cardiac index, thoracic fluid index, stroke index, ejection velocity index, and ventricular ejection time data were averaged during four different gravity (g) states: 1.3g (before parabola onset); 1.9g (parabola entry); 0g (parabola peak); and 1.7g (parabola exit) for each subject. The standing position was associated with the largest changes in the cardiovascular response to hypo- and hypergravity. The thoracic fluid index did not indicate a headward redistribution during transition from a simulated launch position to weightlessness. Analysis of the eight to ten parabolas revealed that, in general, values obtained at 1.8g differed from 1.6g, 0g differed from 1.6 and 1.3g, and 1.6g differed from 1.3g. The factors of gravity, thoracic fluid index, and cardiac index exhibited significant differences that were most likely to occur between parabola 1 versus parabolas 6, 7, and 8, and parabola 2 versus parabolas 4 through 8. Only the parameter of thoracic fluid index exhibited significance for parabolas 3 versus parabolas 6 and 7.

Cardiovascular responses to repetitive exposure to hyper- and hypogravity states produced by parabolic flight

NASA Technical Reports Server (NTRS)

Mukai, C. N.; Lathers, C. M.; Charles, J. B.; Bennett, B. S.

1994-01-01

Physiologic changes to repetitive hyper- and hypogravity stresses occurring during eight to ten parabolas on NASA's KC-135 aircraft were studied. Hemodynamic responses in 11 subjects in 4 different postures (supine, standing, sitting, and semisupine Space Shuttle launch position) were determined using noninvasive impedance cardiography. Five seconds of heart rate, cardiac index, thoracic fluid index, stroke index, ejection velocity index, and ventricular ejection time data were averaged during four different gravity (g) states: 1.3g (before parabola onset); 1.9g (parabola entry); 0g (parabola peak); and 1.7g (parabola exit) for each subject. The standing position was associated with the largest changes in the cardiovascular response to hypo- and hypergravity. The thoracic fluid index did not indicate a headward redistribution during transition from a simulated launch position to weightlessness. Analysis of the eight to ten parabolas revealed that, in general, values obtained at 1.8g differed from 1.6g, 0g differed from 1.6 and 1.3g, and 1.6g differed from 1.3g. The factors of gravity, thoracic fluid index, and cardiac index exhibited significant differences that were most likely to occur between parabola 1 versus parabolas 6, 7, and 8, and parabola 2 versus parabolas 4 through 8. Only the parameter of thoracic fluid index exhibited significance for parabolas 3 versus parabolas 6 and 7.

Computer simulations of postural change, water immersion and bedrest - An integrative approach for understanding the spaceflight response

NASA Technical Reports Server (NTRS)

Leonard, J. I.; Leach, C. S.; Rummel, J. A.

1982-01-01

Mathematical modeling techniques were used to simulate the fluid electrolyte (F-E) responses during gravity unloading. It is shown that the response to weightlessness can best be understood by separately examining the acute (hours to days) and chronic (days to weeks) phases, and assuming the presence of normal, although complex, feedback regulatory processes. Headward shifts of fluid are shown to be primarily responsible for acute body losses of extracellular F-E. Losses of body water are closely related to the volume of fluid shifts from the legs. A diuresis is predicted within the first several hours of hypogravity, and this may be obscured by a reduced F-E intake; on Skylab, early F-E losses occurred primarily by deficit intake.

The effect of hypogravity and hypergravity on cells of the immune system

NASA Technical Reports Server (NTRS)

Cogoli, A.

1993-01-01

This article reviews the gravity effects discovered in T lymphocytes and other cells of the immune system. The strong depression of mitogenic activation first observed in an experiment conducted in Spacelab 1 in 1983 triggered several other investigations in space and on the ground in the clinostat and in the centrifuge in the past 10 years. During this period, great progress was made in our knowledge of the complex mechanism of T cell activation as well as the technology to analyze the lymphokines produced during stimulation. Nevertheless, several aspects of the steps leading to activation are not yet clear. Studies in hypogravity and hypergravity may contribute to answering some of the questions. A recent investigation in the U.S. Spacelab SLS-1, based on a new technology in which leukocytes are attached to microcarrier beads, showed that the strong inhibition of activation in microgravity is due to a malfunction of monocytes acting as accessory cells. In fact, interleukin-1 production is nearly nil in resuspended monocytes, whereas T cell activation is doubled in attached cells. In hypergravity, but not at 1g, concanavalin A bound to erythrocytes activates B lymphocytes in addition to T cells. The activation of Jurkat cells is also severely impaired in space. These recent results have raised new questions that have to be answered in experiments to be conducted in space and on Earth in this decade. The experimental system, based on the mitogenic activation of T lymphocytes and accessory cells attached to microcarriers, offers an optimum model for studying basic biological mechanisms of the cell to assess the immunological fitness of humans in space and to test the feasibility of bioprocesses in space as well as on Earth.

Evaluation of biological models using Spacelab

NASA Technical Reports Server (NTRS)

Tollinger, D.; Williams, B. A.

1980-01-01

Biological models of hypogravity effects are described, including the cardiovascular-fluid shift, musculoskeletal, embryological and space sickness models. These models predict such effects as loss of extracellular fluid and electrolytes, decrease in red blood cell mass, and the loss of muscle and bone mass in weight-bearing portions of the body. Experimentation in Spacelab by the use of implanted electromagnetic flow probes, by fertilizing frog eggs in hypogravity and fixing the eggs at various stages of early development and by assessing the role of the vestibulocular reflex arc in space sickness is suggested. It is concluded that the use of small animals eliminates the uncertainties caused by corrective or preventive measures employed with human subjects.

Responses of amino acids in hindlimb muscles to recovery from hypogravity and unloading by tail-cast suspension

NASA Technical Reports Server (NTRS)

Tischler, M. E.; Henriksen, E. J.; Jacob, S.; Cook, P. H.

1985-01-01

Amino acids were assayed in muscles from rats exposed to 7 days of hypogravity and 12 h of gravity (F) or 6 days of suspension with (R) or without (H) 12 h of loading. In these groups, lower aspartate was common only to the soleus (SOL) relative to control muscles, the smallest difference being in group R. This difference in aspartate for F and H, but not for R, correlated with lower malate suggesting diminution of citric acid cycle intermediates. The R SOL value was increased over the H SOL. Therefore desite 12 h of loading, the F SOL was more comparable to the H SOL. The role of stress in preventing recovery of the F SOL was apparent from the ratios of glutamine/glutamate. Synthesis of glutamine is enhanced by glucocorticoids and is reflected by an increased ratio. In 5 of the 6 F muscles studied, this ratio was greater than in controls. In contrast, the ratio in all R muscles was similar to controls and showed recovery from the values in H muscles. Hence the post-flight treatment of F rats may have produced additional stress. Despite this stress, in some respects the SOL responses to hypogravity were similar to its responses to unloding by suspension.

Hypogravity Research and Educational Parabolic Flight Activities Conducted in Barcelona: a new Hub of Innovation in Europe

NASA Astrophysics Data System (ADS)

Perez-Poch, Antoni; González, Daniel Ventura; López, David

2016-12-01

We report on different research and educational activities related to parabolic flights conducted in Barcelona since 2008. We use a CAP10B single-engine aerobatic aircraft flying out of Sabadell Airport and operating in visual flight conditions providing up to 8 seconds of hypogravity for each parabola. Aside from biomedical experiments being conducted, different student teams have flown in parabolic flights in the framework of the international contest `Barcelona Zero-G Challenge', and have published their results in relevant symposiums and scientific journals. The platform can certainly be a good testbed for a proof-of-concept before accessing other microgravity platforms, and has proved to be excellent for motivational student campaigns.

Muscle protein and glycogen responses to recovery from hypogravity and unloading by tail-cast suspension

NASA Technical Reports Server (NTRS)

Henriksen, E. J.; Tischler, M. E.; Jacob, S.; Cook, P. H.

1985-01-01

Previous studies in this laboratory using the tail-bast hindlimb suspension model have shown that there are specific changes in protein and carbohydrate metabolism in the soleus muscle due to unloading. For example, 6 days of unloading caused a 27% decrease in mass and a 60% increase in glycogen content in the soleus muscle, while the extensor digitorum longus muscle was unaffected. Also, fresh tissue tyrosine and its in vitro release from the muscle are increased in the unloaded soleus, indicating that this condition causes a more negative protein balance. With these results in mind, studies to investigate the effect of hypogravity on protein and carbohydrate metabolism in a number of rat hindlimb muscles were carried out.

Muscle protein and glycogen responses to recovery from hypogravity and unloading by tail-cast suspension

NASA Technical Reports Server (NTRS)

Henriksen, E. J.; Tischler, M. E.; Jacob, S.; Cook, P. H.

1985-01-01

Previous studies in this laboratory using the tail-bast hindlimb suspension model have shown that there are specific changes in protein and carbohydrate metabolism in the soleus muscle due to unloading. For example, 6 days of unloading caused a 27 percent decrease in mass and a 60 percent increse in glycogen content in the soleus muscle, while the extensor digitorum longus muscle was unaffected. Also, fresh tissue tyrosine and its in vitro release from the muscle are increased in the unloaded soleus, indicating that this condition causes a more negative protein balance. With these results in mind, studies to investigate the effect of hypogravity on protein and carbohydrate metabolism in a number of rat hindlimb muscles were carried out.

Hypo-gravity and immune system effects

NASA Technical Reports Server (NTRS)

Carter, Paul D.; Barnes, Frank

1990-01-01

Recent studies on the effects of hypo-gravity on astronauts have shown depressed response of the immune system component cells (e.g. T-lymphocytes activity) and associated bone-mass loss due to demineralization. The widespread use of various electrical stimulation techniques in fracture repair and bone growth make use of the inherent piezoelectric and streaming potentials in Ca(2++) depositation. In-vitro and in-vivo experiments were designed to determine if these potentials, absent or greatly reduced in space, could be artificially enhanced to advantageously effect the bone marrow and, consequently, immune system cells. The bone marrow plays an extremely important role in the development and maturation of all blood cells and, specifically, T- and B-lymphocytes. It is our belief that simulated E-fields will enhance this development when 'ambient' physiological fields are absent during spaceflight or extended bedrest. Our investigation began with a look at the component immune system cells and their growth patterns in vitro. The first chamber will induce E-fields by current densities produced from an agar-bridge electrode arrangement. The cells are immersed in a nutrient agar and isolated from the electrodes by an agar bridge to prevent electrolytic contamination. The second chamber induces current densities by mutual induction from a magnetic field produced by a solenoid coil. Cells are isolated in a small radial area to reduce (1/r) effects and for accurate field calculations. We anticipate inducing currents in the nano- and microampere range as indicated by our calculations of physiological fields.

Effects of Hypogravity on Osteoblast Differentiation

NASA Technical Reports Server (NTRS)

Globus, Ruth; Doty, Steven

1997-01-01

Weightbearing is essential for normal skeletal function. Without weightbearing, the rate of bone formation by osteoblasts decreases in the growing rat. Defective formation may account for the decrease in the maturation, strength and mass of bone that is caused by spaceflight. These skeletal defects may be mediated by a combination of physiologic changes triggered by spaceflight, including skeletal unloading, fluid shifts, and stress-induced endocrine factors. The fundamental question of whether the defects in osteoblast function due to weightlessness are mediated by localized skeletal unloading or by systemic physiologic adaptations such as fluid shifts has not been answered. Furthermore, bone-forming activity of osteoblasts during unloading may be affected by paracrine signals from vascular, monocytic, and neural cells that also reside in skeletal tissue. Therefore we proposed to examine whether exposure of cultured rat osteoblasts to spaceflight inhibits cellular differentiation and impairs mineralization when isolated from the influence of both systemic factors and other skeletal cells.

The role of calcium ions in cytological effects of hypogravity

NASA Astrophysics Data System (ADS)

Kordyum, E. L.; Belyavskaya, N. A.; Nedukha, E. M.; Palladina, T. A.; Tarasenko, V. A.

Electron-cytochemical and biochemical methods made it possible to reveal certain differences in ATPase activity stimulation by calcium ions in root apex cells of pea seedlings and moss protonema Funaria hygrometrica grown under stationary and slow clinostatic (2 rev/min) conditions. It was showed that under clinostatic conditions in comparison with the control variant the ATPase activity decreases in plasmalemma. The protein content in the plasmalemma fraction was also twice as low under these conditions. The root apex cells of the pea seedlings grown under spaceflight conditions were found to contain high concentrations of membrane-bound calcium. The data obtained are discussed in relation to problems of possible mechanisms of disturbance in calcium balance and the system of active calcium ion transport through plasmalemma under hypogravity.

Fluid and electrolyte homeostasis during spaceflight: Elucidation of mechanisms in a primate

NASA Technical Reports Server (NTRS)

Churchill, Susanne

1990-01-01

Although it is now well accepted that exposure to the hypogravic environment of space induces a shift of fluid from the lower extremities toward the upper body, the actual physiological responses to this central volume expansion have not been well characterized. Because it is likely that the fluid and electrolyte response to hypogravity plays a critical role in the development of Cardiovascular Deconditioning, elucidation of these mechanisms is of critical importance. The goal of flight experiment 223, scheduled to fly on SLS-2, is the definition of the basic renal, fluid and electrolyte response to spaceflight in four instrumented squirrel monkeys. The studies were those required to support the development of flight hardware and optimal inflight procedures, and to evaluate a ground-based model for weightlessness, lower body positive pressure (LBPP).

[Perinatal model of human transition from hypogravity to the earth's gravity based on the electromyogram nonlinear characteristics].

PubMed

Meĭgal, A Iu; Voroshilov, A S

2009-01-01

Interferential electromyogram (iEMG) was analyzed in healthy newborn infants (n=29) during the first 24 hours of life as a model of transition from hypogravity (intrauterine immersion) to the Earth's gravity (postnatal period). Nonlinear instruments of iEMG analysis (correlation dimension, entropy and fractal dimension) reflected the complexity, chaotic character and predictability of signals from the leg and arm antagonistic muscles. Except for m. gastrocnemius, in all other musles iEMG fractal dimension was shown to grow as the postnatal period extended. Low fractal and correlation dimensions and entropy marked flexor muscles, particularly against low iEMG amplitude suggesting a better congenital programming for the flexors as compared to the extensors. It is concluded that the early ontogenesis model can be practicable in studying the evolution and states of antigravity functions.

Some Pecularities of the Graviresponse in Vaucheria

NASA Technical Reports Server (NTRS)

Gavrilova, O. V.; Rudanova, E. E.; Voloshko, L. N.; Gabova, A. V.

1996-01-01

The growth and position of nuclei in the siphonaceous alga Vaucheria sessilis were investigated under conditions of hypergravity and hypogravity. Under hypergravity conditions, active sporogenesis was observed. The accumulation of nuclei in the apical and branching zone preceeded the sporogenesis. The anti-microtubular agent, colchicine inhibits sporogenesis and the response of Vaucheria to hypergravity. Under hypogravity conditions, the quantity of nuclei increased throughout the whole branch. Colchicine prevents the migration of nuclei from the apical zone to the basal part of the branch. The anti-actin agent phalloidin prevents the formation of an actin network, and phalloidin-poisoned cells lose a cluster of nuclei in the apical zone. However, the gravity dependent response is less pronounced. It is supposed that, in Vaucheria sessilis, the primary stages of the reception and translation of gravitational signals coincide with those for light signals and active division of nuclei in the growth zone is an integral part of the graviresponse.

Response of Ambulatory Human Subjects to Artificial Gravity (Short Radius Centrifugation)

NASA Technical Reports Server (NTRS)

Paloski, William H.; Arya, Maneesh; Newby, Nathaniel; Tucker, Jon-Michael; Jarchow, Thomas; Young, Laurence

2006-01-01

Prolonged exposure to microgravity results in significant adaptive changes, including cardiovascular deconditioning, muscle atrophy, bone loss, and sensorimotor reorganization, that place individuals at risk for performing physical activities after return to a gravitational environment. Planned missions to Mars include unprecedented hypogravity exposures that would likely result in unacceptable risks to crews. Artificial gravity (AG) paradigms may offer multisystem protection from the untoward effects of adaptation to the microgravity of space or the hypogravity of planetary surfaces. While the most effective AG designs would employ a rotating spacecraft, perceived issues may preclude their use. The questions of whether and how intermittent AG produced by a short radius centrifuge (SRC) could be employed have therefore sprung to the forefront of operational research. In preparing for a series of intermittent AG trials in subjects deconditioned by bed rest, we have examined the responses of several healthy, ambulatory subjects to SRC exposures.

Research on the adaptation of skeletal muscle to hypogravity: Past and future directions

NASA Astrophysics Data System (ADS)

Riley, D. A.; Ellis, S.

Our current understanding of hypogravity-induced atrophy of skeletal muscles is based primarily on studies comparing pre- and post-flight properties of muscles. Interpretations are necessarily qualified by the assumption that the stress of reentry and readjustment to terrestrial gravity do not alter the parameters being analyzed. The neuromuscular system is highly responsive to changes in functional demands and capable of rapid adaptation, making this assumption questionable. A reexamination of the changes in the connective tissue and synaptic terminals of soleus muscles from rats orbited in biosatellites and sampled postflight indicates that these structural alterations represent adaptative responses of the atrophic muscles to the increased workload of returning to 1 G, rather than hypogravity per se. The atrophy of weightlessness is postulated to result because muscles are both underloaded and used less often. Proper testing of this hypothesis requires quantitation of muscle function by monitoring electromyography, force output and length changes during the flight. Experiments conducted in space laboratories, like those being developed for the Space Shuttle, will avoid the complications of reentry before tissue sampling and allow time course studies of the rate of development of adaptive changes to zero gravity. Another area of great importance for future studies of muscle atrophy is inflight measurement of plasma levels of hormones and tissue receptor levels. Glucocorticoids, thyroid hormone and insulin exert dramatic regulatory influences on muscle structure. Prevention of neuromuscular atrophy becomes increasingly more important as spaceflights increase in duration. Definition of the atrophic mechanism is essential to developing means of preventing neuromuscular atrophy.

[The antigravity suit, chamberless type, as a means of increasing orthostatic tolerance after water immersion hypokinesis and acceleration].

PubMed

Shul'zhenko, E B; Kozlova, V G; Kurdin, K A; Iarov, A S; Plokhova, V G

1983-01-01

Orthostatic tolerance after 7-day dry immersion and head-to-feet acceleration was investigated on test subjects with and without an antigravity suit of bladderless type. With the suit on, the 20 min tilt test at 70 degrees prior to immersion induced less marked changes than without the suit. When the suit was on, cardiovascular reactions to tilt tests after immersion and acceleration improved. The maximum heart rate decreased from 135 +/- 4 to 101 +/- 5 beats/min (p less than 0.01), minimum stroke volume increased from 29 +/- 2 to 41 +/- 3 ml (p less than 0.05), and pulse pressure grew. Thus, an antigravity suit may help increase initial orthostatic tolerance and maintain it after the combined effect of simulated hypogravity and acceleration.

Importance of gravity for plant growth and behavior

NASA Technical Reports Server (NTRS)

Brown, A. H.

1984-01-01

Accomplishments during the past fiscal year consisted of (1) completion of research on a study of the kinetics of damping out of circummutation when the axially directed g-force was abruptly eliminated (Research Task NULYRL). (2) Further experiments were accomplished on a comprehensive study, underway for several years, to validate (or invalidate) the use of clinostat rotation as a hypogravity simulation device. (3) Some of our earlier (unpublished) observations on plant seedlings resistance to g-loading were evaluated, interpreted, and a paper was submitted for publication (Research Task HYGEFF). (4) In what has been called ""Shuttle middeck locker ecology" an attempt to acquire reliable empirical information on the thermal profile experienced by test packages housed in middeck lockers (MDDL) during shuttle flights at long last seems to be yielding some results.

Piracetam and fish orientation during parabolic aircraft flight

NASA Technical Reports Server (NTRS)

Hoffman, R. B.; Salinas, G. A.; Homick, J. L.

1980-01-01

Goldfish were flown in parabolic Keplerian trajectories in a KC-135 aircraft to assay both the effectiveness of piracetam as an antimotion sickness drug and the effectiveness of state-dependent training during periods of oscillating gravity levels. Single-frame analyses of infrared films were performed for two classes of responses - role rates in hypogravity or hypogravity orienting responses (LGR) and climbing responses in hypergravity or hypergravity orienting responses (HGR). In Experiment I, preflight training with the vestibular stressor facilitated suppression of LGR by the 10th parabola. An inverse correlation was found between the magnitudes of LGR and HGR. Piracetam was not effective in a state-dependent design, but the drug did significantly increase HGR when injected into trained fish shortly before flight. In Experiment II, injections of saline, piracetam, and modifiers of gamma-aminobutyric acid - aminooxyacetic acid (AOAA) and isonicotinic acid did not modify LGR. AOAA did significantly increase HGR. Thus, the preflight training has a beneficial effect in reducing disorientation in the fish in weightlessness, but the drugs employed were ineffective.

Effect of simulated space gravity environment on Gibberella moniliformis EZG0807.

PubMed

Yan, Jvfen; Shang, Peng; Zheng, De; Dong, Yuanyuan; Mao, Jun; Wang, Suping; Liu, Xin; Yang, Shulin

2012-05-01

To determine the feasibility of inducing mutation for Gibberella moniliformis EZG0807 with a superconducting magnet, this paper investigated the effects of this instrument on the filamentous fungus G. moniliformis EZG0807. The superconducting magnet could simulate space gravity environment from hypo-gravity (0 g) to hyper-gravity (2 g). After G. moniliformis EZG0807 was exposed to the superconducting magnet for 72 h, the morphological observation, agar diffusion method, and amplified fragment length polymorphism were performed to detect the mutagenic effects in the aspect of morphology, the activity of metabolites, and genomic DNA, respectively. The mutant strain M7212 in 1 g (16 T) was different from the control in the morphology, showing no activity against the four tested bacteria Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and Proteus vulgaris, and lost a size of 675 bp band on the genomic DNA. These results indicated that the superconducting magnet could be used to induce mutation for G. moniliformis EZG0807, which enabled improving the production of G. moniliformis EZG0807 and providing an effective approach for fungal breeding.

Ground Reaction Forces During Locomotion in Simulated Microgravity

NASA Technical Reports Server (NTRS)

Davis, B. L.; Cavanagh, Peter R.; Sommer, H. J., III; Wu, G.

1996-01-01

Significant losses in bone density and mineral, primarily in the lower extremities have been reported following exposure to weightlessness. Recent investigations suggest that mechanical influences such as bone deformation and strain rate may be critically important in stimulating new bone formation. It was hypothesized that velocity, cadence and harness design would significantly affect lower limb impact forces during treadmill exercise in simulated zero gravity (0G). A ground-based hypogravity simulator was used to investigate which factors affect limb loading during tethered treadmill exercise. A fractional factorial design was used and 12 subjects were studied. The results showed that running on active and passive treadmills in the simulator with a tethering force close to the maximum comfortable level produced similar magnitudes for the peak ground reaction force. It was also found that these maximum forces were significantly lower than those obtained during overground trials, even when the speeds of locomotion in the simulator were 66 % greater than those in 1 G. Cadence had no effect on any of the response variables. The maximum rate of force application (DFDT-Max) was similar for overground running and exercise in simulated 0G, provided that the "weightless subjects ran on a motorized treadmill. These findings have implications for the use of treadmill exercise as a countermeasure for hypokinetic osteoporosis. As the relationship between mechanical factors and osteogenesis becomes better understood, results from human experiments in 0G simulators will help to design in-flight exercise programs that are more closely targeted to generate appropriate mechanical stimuli.

Afferent control mechanisms involved in the development of soleus fiber alterations in simulated hypogravity

NASA Astrophysics Data System (ADS)

Shenkman, B. S.; Nemirovskaya, T. L.; Shapovalova, K. B.; Podlubnaya, Z. A.; Vikhliantsev, I. M.; Moukhina, A. M.; Kozlovskaya, I. B.

2007-02-01

It was recently established that support withdrawal (withdrawal of support reaction force) in microgravity provokes a sequence of functional shifts in the activity of motor units (inactivation of slow ones) and peripheral muscle apparatus which lead to the decline of postural muscle contractility and alterations in fiber characteristics. However, mechanisms involved in inactivation of the slow motor units and appropriate slow-twitch muscle fiber disuse under the supportless conditions remained unknown. We show here that artificial inactivation of muscles-antagonists (which are known to be hyperactive during unloading) counteracts some of the unloading-induced events in the rat soleus (fiber size reduction, slow-to-fast fiber-type transition and decline of titin and nebulin content). It was also demonstrated that direct activation of the muscarinic receptors of the neostriatum neurons prevented slow-to-fast fiber-type transformation in soleus of hindlimb suspended rats.

Response of lymphocytes to a mitogenic stimulus during spaceflight

NASA Technical Reports Server (NTRS)

Sonnenfeld, Gerald

1989-01-01

Several studies were performed that demonstrate that immunological activities of lymphocytes can be affected by spaceflight or by models that attempt to simulate some aspects of weightlessness. Included among these are the responses of lymphocytes to external stimuli such as mitogens and viruses. When cultures of lymphocytes were flown in space, the ability of the lymphocytes to respond to mitogens was inhibited. Similar results were obtained when lymphocytes from astronauts or animals just returned from space were placed into culture immediately upon return to earth, and when models of hypogravity were used. Lymphocytes placed in culture during spaceflights produced enhanced levels of interferon compared to control cultures. When cultures of lymphocytes were prepared for cosmonauts or rodents immediately upon return to earth, interferon production was inhibited. These results suggest that space flight can have profound effects on lymphocyte function, and that effects on isolated cells may be different from that on cells in the whole organism.

Retinal changes in rats flown on Cosmos 936 - A cosmic ray experiment

NASA Technical Reports Server (NTRS)

Philpott, D. E.; Corbett, R.; Turnbill, C.; Black, S.; Dayhoff, D.; Mcgourty, J.; Lee, R.; Harrison, G.; Savik, L.

1980-01-01

Ten rats, five centrifuged during flight to simulate gravity and five stationary in flight and experiencing hypogravity, orbited the Earth. No differences were noted between flight-stationary and flight-centrifuged animals, but changes were seen between these two groups and ground controls. Morphological alterations were observed comparable to those in the experiment flown on Cosmos 782 and to the retinal cells exposed to high-energy particles at Berkeley. Affected cells in the outer nuclear layer showed swelling, clearing of cytoplasm, and disruption of the membranes. Tissue channels were again found, similar to those seen on 782. After space flight, preliminary data indicated an increase in cell size in montages of the nuclear layer of both groups of flight animals. This experiment shows that weightlessness and environmental conditions other than cosmic radiation do not contribute to the observed damage of retinal cells.

The effects of simulated hypogravity on murine bone marrow cells

NASA Technical Reports Server (NTRS)

Lawless, Desales

1989-01-01

Mouse bone marrow cells grown in complete medium at unit gravity were compared with a similar population cultured in conditions that mimic some aspects of microgravity. After the cells adjusted to the conditions that simulated microgravity, they proliferated as fetal or oncogenic populations; their numbers doubled in twelve hour periods. Differentiated subpopulations were depleted from the heterogeneous mixture with time and the undifferentiated hematopoietic stem cells increased in numbers. The cells in the control groups in unit gravity and those in the bioreactors in conditions of microgravity were monitored under a number of parameters. Each were phenotyped as to cell surface antigens using a panel of monoclonal antibodies and flow cytometry. Other parameters compared included: pH, glucose uptake, oxygen consumption and carbon-dioxide production. Nuclear DNA was monitored by flow cytometry. Functional responses were studied by mitogenic stimulation by various lectins. The importance of these findings should have relevance to the space program. Cells should behave predictably in zero gravity; specific populations can be eliminated from diverse populations and other populations isolated. The availability of stem cell populations will enhance both bone marrow and gene transplant programs. Stem cells will permit developmental biologists study the paths of hematopoiesis.

Human Locomotion under Reduced Gravity Conditions: Biomechanical and Neurophysiological Considerations

PubMed Central

Sylos-Labini, Francesca; Ivanenko, Yuri P.

2014-01-01

Reduced gravity offers unique opportunities to study motor behavior. This paper aims at providing a review on current issues of the known tools and techniques used for hypogravity simulation and their effects on human locomotion. Walking and running rely on the limb oscillatory mechanics, and one way to change its dynamic properties is to modify the level of gravity. Gravity has a strong effect on the optimal rate of limb oscillations, optimal walking speed, and muscle activity patterns, and gait transitions occur smoothly and at slower speeds at lower gravity levels. Altered center of mass movements and interplay between stance and swing leg dynamics may challenge new forms of locomotion in a heterogravity environment. Furthermore, observations in the lack of gravity effects help to reveal the intrinsic properties of locomotor pattern generators and make evident facilitation of nonvoluntary limb stepping. In view of that, space neurosciences research has participated in the development of new technologies that can be used as an effective tool for gait rehabilitation. PMID:25247179

Prevention of bone mineral changes induced by bed rest: Modification by static compression simulating weight bearing, combined supplementation of oral calcium and phosphate, calcitonin injections, oscillating compression, the oral diophosphonatedisodium etidronate, and lower body negative pressure

NASA Technical Reports Server (NTRS)

Schneider, V. S.; Hulley, S. B.; Donaldson, C. L.; Vogel, J. M.; Rosen, S. N.; Hantman, D. A.; Lockwood, D. R.; Seid, D.; Hyatt, K. H.; Jacobson, L. B.

1974-01-01

The phenomenon of calcium loss during bed rest was found to be analogous to the loss of bone material which occurs in the hypogravic environment of space flight. Ways of preventing this occurrence are investigated. A group of healthy adult males underwent 24-30 weeks of continuous bed rest. Some of them were given an exercise program designed to resemble normal ambulatory activity; another subgroup was fed supplemental potassium phosphate. The results from a 12-week period of treatment were compared with those untreated bed rest periods. The potassium phosphate supplements prevented the hypercalciuria of bed rest, but fecal calcium tended to increase. The exercise program did not diminish the negative calcium balance. Neither treatment affected the heavy loss of mineral from the calcaneus. Several additional studies are developed to examine the problem further.

Invariant aspects of human locomotion in different gravitational environments.

PubMed

Minetti, A E

2001-01-01

Previous literature showed that walking gait follows the same mechanical paradigm, i.e. the straight/inverted pendulum, regardless the body size, the number of legs, and the amount of gravity acceleration. The Froude number, a dimensionless parameter originally designed to normalize the same (pendulum-like) motion in differently sized subjects, proved to be useful also in the comparison, within the same subject, of walking in heterogravity. In this paper the theory of dynamic similarity is tested by comparing the predictive power of the Froude number in terms of walking speed to previously published data on walking in hypogravity simulators. It is concluded that the Froude number is a good first predictor of the optimal walking speed and of the transition speed between walking and running in different gravitational conditions. According to the Froude number a dynamically similar walking speed on another planet can be calculated as [formula: see text] where V(Earth) is the reference speed on Earth. c 2001. Elsevier Science Ltd. All rights reserved.

Hypogravity's Effect on the Life Cycle of Japanese Quail

NASA Technical Reports Server (NTRS)

Hester, Patricia Y.

1999-01-01

A series of studies were conducted to determine the effect of activities preceding space-flight and during space-flight on quail embryonic development. While the overall development of the quail embryos was evaluated, the report presented herein, focused on calcium utilization or uptake from eggshells by developing embryos during incubation in space and on earth. In the pre-space trials, fertilized quail eggs were subjected to pre-night dynamics including forces of centrifugation, vibration, or a combination of vibration and centrifugation prior to incubation for 6 or 16 days. In another trial, fertile quail eggs were tested for survivability in a refrigerator stowage kit for eggs (RSKE) which was subsequently used to transport the eggs to space. Eggs in the RSKE were subjected to shuttle launch dynamics including G force and random vibration profiles. In the space- flight trials, 48 fertile quail eggs were launched on space shuttle Flight STS-76 and were subsequently incubated in a Slovakian incubator onboard space station, MIR. Two sets of ground controls each with 48 fertile eggs with and without exposure to launch dynamics were initiated 5 days post-launch. There was a laboratory control (incubated in Lyon RX2 incubator at 37.5 C) and a synchronous control (incubated in Lyon RX2 incubator at 39 - 400 C), which simulated the temperature of the space-flight incubator. Following space-flight trials, post-flight trials were conducted where quail eggs were incubated in Lyon RX2 or Slovakian incubators under various temperatures with or without launch dynamics. Eggshells from all study trials were retrieved and analyzed for calcium content to determine if its utilization by developing quail embryos was affected by activities preceding space-flight or during incubation in space under microgravity. Results from the pre-flight and post-flight showed that pre-flight activities and shuttle launch dynamics had no effect on calcium uptake from the eggshell by developing embryos. However, calcium uptake from the eggshell by developing embryos incubated in micro,aravity was impaired by 12.6% when compared to embryos incubated on earth under laboratory control environment. This impairment was unlikely due to factors other than microgravity. In general, calcium utilization by developing embryos increased with age of incubation with the most increase occurring at day 16 of incubation.

The Mars Gravity Simulation Project

NASA Technical Reports Server (NTRS)

Korienek, Gene

1998-01-01

Human beings who make abrupt transitions between one gravitational environment and another undergo severe disruptions of their visual perception and visual- motor coordination, frequently accompanied by "space sickness." Clearly, such immediate effects of exposure to a novel gravitational condition have significant implications for human performance. For example, when astronauts first arrive in Earth orbit their attempts to move about in the spacecraft and to perform their duties are uncoordinated, inaccurate, and inefficient. Other inter-gravitational transitions for which these difficulties can be expected include going from the 0 g of the spacecraft to the. 16 g of the Moon, from 0 g to the .38 g of Mars, and from 0 g back to the 1.0 g of Earth. However, after astronauts have actively interacted with their new gravitational environment for several days, these problems tend to disappear, evidence that some sort of adaptive process has taken place. It would be advantageous, therefore, if there were some way to minimize or perhaps even to eliminate this potentially hazardous adaptive transition period by allowing astronauts to adapt to the altered gravitational conditions before actually entering them. Simultaneous adaptations to both the altered and the normal gravitational environment as a result of repeatedly adapting to one and readapting to the other, a phenomenon known as dual adaptation. The objective of the Mars Gravity Simulator (MGS) Project is to construct a simulation of the visual and bodily effects of altered gravity. This perceptual-motor simulation is created through the use of: 1) differential body pressure to produce simulated hypo-gravity and 2) treadmill-controlled virtual reality to create a corresponding visual effect. It is expected that this combination will produce sensory motor perturbations in the subjects. Both the immediate and adaptive behavioral (postural and ambulatory) responses to these sensory perturbations will be assessed.

[Issues of biomedical support of explorations missions].

PubMed

Potapov, A N; Sinyak, Yu E; Petrov, V M

2013-01-01

Sine qua non for piloted exploration missions is a system of biomedical support. The future system will be considerably different from the analogous systems applied in current orbital missions. The reason is the challenging conditions in expeditions to remote space. In a mission to Mars, specifically, these are high levels of radiation, hypomagnetic environment, alternation of micro- and hypogravity, very long mission duration and autonomy. The paper scrutinizes the major issues of medical support to future explorers of space.

Is Bone Tissue Really Affected by Swimming? A Systematic Review

PubMed Central

Gómez-Bruton, Alejandro; Gónzalez-Agüero, Alejandro; Gómez-Cabello, Alba; Casajús, José A.; Vicente-Rodríguez, Germán

2013-01-01

Background Swimming, a sport practiced in hypogravity, has sometimes been associated with decreased bone mass. Aim This systematic review aims to summarize and update present knowledge about the effects of swimming on bone mass, structure and metabolism in order to ascertain the effects of this sport on bone tissue. Methods A literature search was conducted up to April 2013. A total of 64 studies focusing on swimmers bone mass, structure and metabolism met the inclusion criteria and were included in the review. Results It has been generally observed that swimmers present lower bone mineral density than athletes who practise high impact sports and similar values when compared to sedentary controls. However, swimmers have a higher bone turnover than controls resulting in a different structure which in turn results in higher resistance to fracture indexes. Nevertheless, swimming may become highly beneficial regarding bone mass in later stages of life. Conclusion Swimming does not seem to negatively affect bone mass, although it may not be one of the best sports to be practised in order to increase this parameter, due to the hypogravity and lack of impact characteristic of this sport. Most of the studies included in this review showed similar bone mineral density values in swimmers and sedentary controls. However, swimmers present a higher bone turnover than sedentary controls that may result in a stronger structure and consequently in a stronger bone. PMID:23950908

Possible mechanism for changes in glycogen metabolism in unloaded soleus muscle

NASA Technical Reports Server (NTRS)

Henriksen, E. J.; Tischler, M. E.

1985-01-01

Carbohydrate metabolism has been shown to be affected in a number of ways by different models of hypokinesia. In vivo glycogen levels in the soleus muscle are known to be increased by short-term denervation and harness suspension. In addition, exposure to 7 days of hypogravity also caused a dramatic increase in glycogen concentration in this muscle. The biochemical alterations caused by unloading that may bring about these increases in glycogen storage in the soleus were sought.

Advanced Magnetic Materials Methods and Numerical Models for Fluidization in Microgravity and Hypogravity

NASA Technical Reports Server (NTRS)

Atwater, James; Wheeler, Richard, Jr.; Akse, James; Jovanovic, Goran; Reed, Brian

2013-01-01

To support long-duration manned missions in space such as a permanent lunar base, Mars transit, or Mars Surface Mission, improved methods for the treatment of solid wastes, particularly methods that recover valuable resources, are needed. The ability to operate under microgravity and hypogravity conditions is essential to meet this objective. The utilization of magnetic forces to manipulate granular magnetic media has provided the means to treat solid wastes under variable gravity conditions by filtration using a consolidated magnetic media bed followed by thermal processing of the solid wastes in a fluidized bed reactor. Non-uniform magnetic fields will produce a magnetic field gradient in a bed of magnetically susceptible media toward the distributor plate of a fluidized bed reactor. A correctly oriented magnetic field gradient will generate a downward direct force on magnetic media that can substitute for gravitational force in microgravity, or which may augment low levels of gravity, such as on the Moon or Mars. This approach is termed Gradient Magnetically Assisted Fluidization (G-MAFB), in which the magnitude of the force on the fluidized media depends upon the intensity of the magnetic field (H), the intensity of the field gradient (dH/dz), and the magnetic susceptibility of the media. Fluidized beds based on the G-MAFB process can operate in any gravitational environment by tuning the magnetic field appropriately. Magnetic materials and methods have been developed that enable G-MAFB operation under variable gravity conditions.

Effect of confinement in small space flight size cages on insulin sensitivity of exercise-trained rats

NASA Technical Reports Server (NTRS)

Mondon, C. E.; Dolkas, C. B.; Reaven, G. M.

1983-01-01

The effect of confinement in small cages (simulating the size to be used in future space Shuttle missions) on insulin sensitivity was studied in rats having an increased insulin sensitivity due to exercise training prior to confinement. Oral glucose tolerance tests (OGTT) were given to both control and exercise-trained rats before and after placement in the small cages for 7 days. The insulin resistance was assessed by the product of the area of the insulin and glucose curves of the OGTT (IG index). Results show that the values obtained before confinement were one-half as high in exercise-trained rats as those in control rats, reflecting an increased sensitivity to insulin with exercise training. After 7 days confinement, the IG index was found to be not significantly different from initial values for both control and exercise-trained rats. These findings suggest that increased insulin sensitivity in exercise-trained rats persists 7 days after cessation of running activity. The data also indicate that exercise training, before flight, may be beneficial in minimizing the loss of insulin sensitivity expected with decreased use of gravity dependent muscles during exposure to hypogravity in space flight.

Instilling positive beliefs about disabilities: pilot testing a novel experiential learning activity for rehabilitation students.

PubMed

Silverman, Arielle M; Pitonyak, Jennifer S; Nelson, Ian K; Matsuda, Patricia N; Kartin, Deborah; Molton, Ivan R

2018-05-01

To develop and test a novel impairment simulation activity to teach beginning rehabilitation students how people adapt to physical impairments. Masters of Occupational Therapy students (n = 14) and Doctor of Physical Therapy students (n = 18) completed the study during the first month of their program. Students were randomized to the experimental or control learning activity. Experimental students learned to perform simple tasks while simulating paraplegia and hemiplegia. Control students viewed videos of others completing tasks with these impairments. Before and after the learning activities, all students estimated average self-perceived health, life satisfaction, and depression ratings among people with paraplegia and hemiplegia. Experimental students increased their estimates of self-perceived health, and decreased their estimates of depression rates, among people with paraplegia and hemiplegia after the learning activity. The control activity had no effect on these estimates. Impairment simulation can be an effective way to teach rehabilitation students about the adaptations that people make to physical impairments. Positive impairment simulations should allow students to experience success in completing activities of daily living with impairments. Impairment simulation is complementary to other pedagogical methods, such as simulated clinical encounters using standardized patients. Implication of Rehabilitation It is important for rehabilitation students to learn how people live well with disabilities. Impairment simulations can improve students' assessments of quality of life with disabilities. To be beneficial, impairment simulations must include guided exposure to effective methods for completing daily tasks with disabilities.

Effects of Space Flight, Clinorotation, and Centrifugation on the Growth and Metabolism of Escherichia Coli

NASA Technical Reports Server (NTRS)

Brown, Robert B.

1999-01-01

Previous experiments have shown that space flight stimulates bacterial growth and metabolism. An explanation for these results is proposed, which may eventually lead to improved terrestrial pharmaceutical production efficiency. It is hypothesized that inertial acceleration affects bacterial growth and metabolism by altering the transport phenomena in the cells external fluid environment. It is believed that this occurs indirectly through changes in the sedimentation rate acting on the bacteria and buoyancy-driven convection acting on their excreted by-products. Experiments over a broad range of accelerations consistently supported this theory. Experiments at I g indicated that higher concentrations of excreted by products surrounding bacterial cells result in a shorter lag phase. Nineteen additional experiments simulated 0 g and 0.5 g using a clinostat, and achieved 50 g, 180 g, and 400 g using a centrifuge. These experiments showed that final cell density is inversely related to the level of acceleration. The experiments also consistently showed that acceleration affects the length of the lag phase in a non-monotonic, yet predictable, manner. Additional data indicated that E. coli metabolize glucose less efficiently at hypergravity, and more efficiently at hypogravity. A space-flight experiment was also performed. Samples on orbit had a statistically significant higher final cell density and more efficient metabolism than did ground controls. These results. which were similar to simulations of 0 g using a clinostat, support the theory that gravity only affects bacterial growth and metabolism indirectly, through changes in the bacteria's fluid environment.

The Effect of Micro-Gravity on in vitro Calcification

NASA Technical Reports Server (NTRS)

Boskey; Stiner; Binderman; Mendelsohn; Doty, S. B.

1997-01-01

The experiment focuses on mineral deposition or calcification of cartilage. The experiments were used to compare the mineral formed in the microgravity of space with that formed on earth. Results of these experiments were anticipated to provide direct insight into how calcification in cartridge and bone may be controlled in space. In the C-2 experiment (STS 66), we found that mineralization started later in the cartridges (both on the ground and in hypo-gravity) than in plastic, and that mineralization appeared to be retarded in hypo-gravity. The flight experiments also showed that the cells differentiated normally, but more slowly than the ground controls, and that the matrix produced was not different from that made on the ground. The purpose of the C-5 experiment was to confirm these findings. The C-5 experiment was flown on STS-72. Because of a computer problem, cells received no gases and no nutrition. The C-7 was flown on STS-77. Ground controls were repeated a week later, however, because there was a problem with the temperature control during the flight, the concurrent ground controls were performed at a different temperature. Despite these problems, the results of the C-2 experiment were confirmed. The cells in the flight cultures did not mature, formed few cartilage nodules, and showed no evidence of mineral deposition up to a culture age of 28 days. Ground controls showed the presence of mineral (based on chemical, spectroscopic, and histochemical analyses) by 21 days. The mineral in these cultures was analogous to that found in calcifying cartilage of young chicks.

Preliminary report of the Hepatic Encephalopathy Assessment Driving Simulator (HEADS) score.

PubMed

Baskin-Bey, Edwina S; Stewart, Charmaine A; Mitchell, Mary M; Bida, John P; Rosenthal, Theodore J; Nyberg, Scott L

2008-01-01

Audiovisual simulations of real-life driving (ie, driving simulators) have been used to assess neurologic dysfunction in a variety of medical applications. However, the use of simulated driving to assess neurologic impairment in the setting of liver disease (ie, hepatic encephalopathy) is limited. The aim of this analysis was to develop a scoring system based on simulated driving performance to assess mild cognitive impairment in cirrhotic patients with hepatic encephalopathy. This preliminary analysis was conducted as part of the Hepatic Encephalopathy Assessment Driving Simulator (HEADS) pilot study. Cirrhotic volunteers initially underwent a battery of neuropsychological tests to identify those cirrhotic patients with mild cognitive impairment. Performance during an audiovisually simulated course of on-road driving was then compared between mildly impaired cirrhotic patients and healthy volunteers. A scoring system was developed to quantify the likelihood of cognitive impairment on the basis of data from the simulated on-road driving. Mildly impaired cirrhotic patients performed below the level of healthy volunteers on the driving simulator. Univariate logistic regression and correlation models indicated that several driving simulator variables were significant predictors of cognitive impairment. Five variables (run time, total map performance, number of collisions, visual divided attention response, and average lane position) were incorporated into a quantitative model, the HEADS scoring system. The HEADS score (0-9 points) showed a strong correlation with cognitive impairment as measured by area under the receiver-operator curve (.89). The HEADS system appears to be a promising new tool for the assessment of mild hepatic encephalopathy.

Parabolic Flights with Single-Engine Aerobatic Aircraft: Flight Profile and a Computer Simulator for its Optimization

NASA Astrophysics Data System (ADS)

Brigos, Miguel; Perez-Poch, Antoni; Alpiste, Francesc; Torner, Jordi; González Alonso, Daniel Ventura

2014-11-01

We report the results of residual acceleration obtained from initial tests of parabolic flights (more than 100 hours) performed with a small single-engine aerobatic aircraft (CAP10B), and propose a method that improves these figures. Such aircraft have proved capable of providing researchers with periods of up to 8 seconds of reduced gravity in the cockpit, with a gravity quality in the range of 0.1 g 0, where g 0 is the gravitational acceleration of the Earth. Such parabolas may be of interest to experimenters in the reduced gravity field, when this range of reduced gravity is acceptable for the experiment undertaken. They have also proven to be useful for motivational and educational campaigns. Furthermore, these flights may be of interest to researchers as a test-bed for obtaining a proof-of-concept for subsequent access to parabolic flights with larger aircraft or other microgravity platforms. The limited cost of the operations with these small aircraft allows us to perform them as part of a non-commercial joint venture between the Universitat Politècnica de Catalunya - BarcelonaTech (UPC), the Barcelona cluster BAIE and the Aeroclub Barcelona-Sabadell. Any improvements in the length and quality of reduced gravity would increase the capabilities of these small aircraft. To that end, we have developed a method based on a simulator for training aerobatic pilots. The simulation is performed with the CAD software for mechanical design Solidworks Motion{circledR }, which is widely distributed in industry and in universities. It specifically simulates the parabolic flight manoeuvre for our small aircraft and enables us to improve different aspects of the manoeuvre. The simulator is first validated with experimental data from the test flights. We have conducted an initial intensive period of specific pilot training with the aid of the simulator output. After such initial simulation-aided training, results show that the reduced gravity quality has significantly improved from 0.1 g 0 to 0.05 g 0. We conclude that single-engine aerobatic aircraft are capable of conducting small hypogravity experiments with the limitations described in the paper.

Human cellular immune responsiveness following space flight

NASA Technical Reports Server (NTRS)

Taylor, G. R.; Dardano, J. R.

1983-01-01

Peripheral circulating lymphocytes were separated from astronaut blood samples three times before and two times after the first four US Space Shuttle flights. The ability of the in vitro T lymphocytes to respond to Phytohemagglutinin by blastogenesis was found to be reduced for each crewmember following spaceflight. In addition, the astronauts experienced a postflight increase in neutrophils and a decrease in eosinophils. These postflight changes in leukocytes are shown to increase with subjectively-evaluated increases in the incidence of inflight stress, indicating that stress, and not hypogravity, is likely to be the major effector of these changes.

Response of amino acids in hindlimb muscles to recovery from hypogravity and unloading by tail-cast suspension

NASA Technical Reports Server (NTRS)

Tischler, M. E.; Henriksen, E. J.; Jacob, S.; Cook, P. H.

1985-01-01

Concentrations of glutamine, glutamate, aspartate (+ asparagine) and alanine were compared in hindlimb muscles of SL-3 and ground control rats. Alanine was lower in the soleus of flown rats but not of suspended animals, with no response in other muscles except a slight increase in the unloaded plantaris. With recovery, alanine in the soleus was elevated. Since no differences in alanine metabolism were found by isolated muscle, changes in muscle alanine are probably due to altered body use of this amino acid leading to varied plasma levels.

Effects of microgravity on rat bone, cartlage and connective tissues

NASA Technical Reports Server (NTRS)

Doty, S.

1990-01-01

The response to hypogravity by the skeletal system was originally thought to be the result of a reduction in weight bearing. Thus a reduced rate of new bone formation in the weight-bearing bones was accepted, when found, as an obvious result of hypogravity. However, data on non-weight-bearing tissues have begun to show that other physiological changes can be expected to occur to animals during spaceflight. This overview of the Cosmos 1887 data discusses these results as they pertain to individual bones or tissues because the response seems to depend on the architecture and metabolism of each tissue under study. Various effects were seen in different tissues from the rats flown on Cosmos 1887. The femur showed a reduced bone mineral content but only in the central region of the diaphysis. This same region in the tibia showed changes in the vascularity of bone as well as some osteocytic cell death. The humerus demonstrated reduced morphometric characteristics plus a decrease in mechanical stiffness. Bone mineral crystals did not mature normally as a result of flight, suggesting a defect in the matrix mineralization process. Note that these changes relate directly to the matrix portion of the bone or some function of bone which slowly responds to changes in the environment. However, most cellular functions of bone are rapid responders. The stimulation of osteoblast precursor cells, the osteoblast function in collagen synthesis, a change in the proliferation rate of cells in the epiphyseal growth plate, the synthesis and secretion of osteocalcin, and the movement of water into or out of tissues, are all processes which respond to environmental change. These rapidly responding events produced results from Cosmos 1887 which were frequently quite different from previous space flight data.

INTEGRITY - Integrated Human Exploration Mission Simulation Facility

NASA Technical Reports Server (NTRS)

Henninger, Donald L.

2002-01-01

It is proposed to develop a high-fidelity ground facility to carry out long-duration human exploration mission simulations. These would not be merely computer simulations - they would in fact comprise a series of actual missions that just happen to stay on earth. These missions would include all elements of an actual mission, using actual technologies that would be used for the real mission. These missions would also include such elements as extravehicular activities, robotic systems, telepresence and teleoperation, surface drilling technology-all using a simulated planetary landscape. A sequence of missions would be defined that get progressively longer and more robust, perhaps a series of five or six missions over a span of 10 to 15 years ranging in duration from 180 days up to 1000 days. This high-fidelity ground facility would operate hand-in-hand with a host of other terrestrial analog sites such as the Antarctic, Haughton Crater, and the Arizona desert. Of course, all of these analog mission simulations will be conducted here on earth in 1-g, and NASA will still need the Shuttle and ISS to carry out all the microgravity and hypogravity science experiments and technology validations. The proposed missions would have sufficient definition such that definitive requirements could be derived from them to serve as direction for all the program elements of the mission. Additionally, specific milestones would be established for the "launch" date of each mission so that R&D programs would have both good requirements and solid milestones from which to .build their implementation plans. Mission aspects that could not be directly incorporated into the ground facility would be simulated via software. New management techniques would be developed for evaluation in this ground test facility program. These new techniques would have embedded metrics which would allow them to be continuously evaluated and adjusted so that by the time the sequence of missions is completed, the best management techniques will have been developed, implemented, and validated. A trained cadre of managers experienced with a large, complex program would then be available.

Microbial Cellulose Assembly in Microgravity

NASA Technical Reports Server (NTRS)

Brown, R. Malcolm, Jr.

1998-01-01

Based on evidence indicating a possible correlation between hypo-gravity conditions and alteration of cellulose production by the gram negative bacterium, Acetobacter xylinum, a ground-based study for a possible long term Space Shuttle flight has been conducted. The proposed experiment for A. xylinum aboard the Shuttle is the BRIC (Biological Research in a Canister), a metal container containing spaces for nine Petri plates. Using a common experimental design, the cellulose production capability as well as the survivability of the A. xylinum strains NQ5 and AY201 have been described. It should now be possible to use the BRIC for the first long term microgravity experiments involving the biosynthesis of cellulose.

Sublethal effects of catch-and-release fishing: measuring capture stress, fish impairment, and predation risk using a condition index

USGS Publications Warehouse

Campbell, Matthew D.; Patino, Reynaldo; Tolan, J.M.; Strauss, R.E.; Diamond, S.

2009-01-01

The sublethal effects of simulated capture of red snapper (Lutjanus campechanus) were analysed using physiological responses, condition indexing, and performance variables. Simulated catch-and-release fishing included combinations of depth of capture and thermocline exposure reflective of environmental conditions experienced in the Gulf of Mexico. Frequency of occurrence of barotrauma and lack of reflex response exhibited considerable individual variation. When combined into a single condition or impairment index, individual variation was reduced, and impairment showed significant increases as depth increased and with the addition of thermocline exposure. Performance variables, such as burst swimming speed (BSS) and simulated predator approach distance (AD), were also significantly different by depth. BSSs and predator ADs decreased with increasing depth, were lowest immediately after release, and were affected for up to 15 min, with longer recovery times required as depth increased. The impairment score developed was positively correlated with cortisol concentration and negatively correlated with both BSS and simulated predator AD. The impairment index proved to be an efficient method to estimate the overall impairment of red snapper in the laboratory simulations of capture and shows promise for use in field conditions, to estimate release mortality and vulnerability to predation.

Experiment K-308: Automatic analysis of muscle fibers from rats subjected to spaceflight

NASA Technical Reports Server (NTRS)

Castleman, K. R.; Chui, L. A.; Vandermeullen, J. P.

1981-01-01

The morphology of histochemically prepared muscle sections from the gastrocnemius and plantaris muscles of flight and vivarium control rats was studied quantitatively. Both fast-twitch and slow-twitch fibers were significantly smaller in flight groups than in control groups. Fibers in group 4F were somewhat larger than in 1F, presumably due to growth after recovery. Fibers in 4V were slightly larger than in 1V, presumably due to age. The slow fibers showed more spaceflight induced size loss than fast fibers, suggesting they suffered more from hypogravity. The proportion of slow fibers was also lower in the flight groups, suggesting spaceflight induced fiber type conversion from slow to fast.

Medical legacy of Apollo. [physiological effects of stresses

NASA Technical Reports Server (NTRS)

Berry, C. A.

1974-01-01

Since Apollo crews enjoyed freedom of movement and experienced many of the same problems as earlier crews, confinement had to be ruled out in the etiology of space flight-related changes. Apollo was a mission of physiological firsts: the first inflight illnesses were reported, and a series of cardiac arrhythmias occurred. The most important physiological changes were decreased cardiovascular responsiveness, reduced red blood cell mass, and musculoskeletal deterioration. Vestibular-related problems were also noted for the first time. Crewmen lost weight as a result of a hypocaloric regimen inflight and a tendency to lose body tissue under hypogravic conditions. Aldosterone production increased causing some intracellular fluid loss. Very few of the crewmen experienced any psychological problems after Apollo.

The Elephant in the Room: Biomedical Challenges for Long Duration Lunar Habitation

NASA Technical Reports Server (NTRS)

Logan, James S.

2009-01-01

This slide presentation reviews 4 biomedical challenges that are involved in long duration lunar habitation: dust, radiation, hypogravity and synergistic effects. The first two of these challenges are reviewed with more in-depth information. The dangers of dust relate to the particle deposition in the lungs. The dangers of radiation are related to the permissible exposure limit (PEL) and the Risk of Exposure Induced Death (REID), a statistical approach pegged to a single radiation effect: Death from cancer directly attributable to the exposure. There has been a realization that radiation is more harmful than predicted. This is demonstrated by showing the change in the recommended career dose limits, have changed between 1989 and 2000.

Gravity as a biochemical determinant

NASA Technical Reports Server (NTRS)

Siegel, S. M.

1978-01-01

Hypogravity effects on the biochemistry of living organisms are surveyed, and the differences found under orbital, clinostat, and flotation conditions are examined. Changes can be transient - such as altered serum hormone and electrolyte levels in man - and disappear shortly after return to earth, or changes can be more persistent or permanent, as seems to be the case for changes in the skeletal system mineral and protein constituents for humans who have been in space. While plant ethylene and peroxidase both increase under orbital, clinostat, or flotation conditions, 3-PGA-dehydrogenase increases under orbital but not clinostat conditions and cytochrome C reductase and malic dehydrogenase are affected by clinostat but not actual free fall conditions. Reasons for these discrepancies are considered.

Mechanisms of Cardiopulmonary Adaptation to Microgravity. Part 1

NASA Technical Reports Server (NTRS)

1997-01-01

Session TA1 includes short reports covering: (1) Indices of Baroreceptor Reflex Sensitivity: The Use in Rehabilitation Medicine and Space Cardiology; (2) +Gz and +Gx Tolerance of Healthy Persons of Non-Flying Trades at Primary Selection of the Centrifuge; (3) Effect of Dry Immersion on Calf Blood Supply During Sustained Contraction and Upright Exercise in Man; (4) Cardiovascular and Valsalva Responses during Parabolic flight; (5) An Analysis of the Cardiovascular Responses under Hyper- and Hypo-Gravity Environments using a Mathematical model; (6) Effect of Very Gradual Onset Rate +Gz Exposures on the Cardiovascular System; and (7) NASA Specialized Center of Research and Training (NSCORT) in Integrated Physiology: Mechanisms of Physiological Adaptations to Microgravity.

Gravitational and magnetic field variations synergize to cause subtle variations in the global transcriptional state of Arabidopsis in vitro callus cultures

PubMed Central

2012-01-01

Background Biological systems respond to changes in both the Earth's magnetic and gravitational fields, but as experiments in space are expensive and infrequent, Earth-based simulation techniques are required. A high gradient magnetic field can be used to levitate biological material, thereby simulating microgravity and can also create environments with a reduced or an enhanced level of gravity (g), although special attention should be paid to the possible effects of the magnetic field (B) itself. Results Using diamagnetic levitation, we exposed Arabidopsis thaliana in vitro callus cultures to five environments with different levels of effective gravity and magnetic field strengths. The environments included levitation, i.e. simulated μg* (close to 0 g* at B = 10.1 T), intermediate g* (0.1 g* at B = 14.7 T) and enhanced gravity levels (1.9 g* at B = 14.7 T and 2 g* at B = 10.1 T) plus an internal 1 g* control (B = 16.5 T). The asterisk denotes the presence of the background magnetic field, as opposed to the effective gravity environments in the absence of an applied magnetic field, created using a Random Position Machine (simulated μg) and a Large Diameter Centrifuge (2 g). Microarray analysis indicates that changes in the overall gene expression of cultured cells exposed to these unusual environments barely reach significance using an FDR algorithm. However, it was found that gravitational and magnetic fields produce synergistic variations in the steady state of the transcriptional profile of plants. Transcriptomic results confirm that high gradient magnetic fields (i.e. to create μg* and 2 g* conditions) have a significant effect, mainly on structural, abiotic stress genes and secondary metabolism genes, but these subtle gravitational effects are only observable using clustering methodologies. Conclusions A detailed microarray dataset analysis, based on clustering of similarly expressed genes (GEDI software), can detect underlying global-scale responses, which cannot be detected by means of individual gene expression techniques using raw or corrected p values (FDR). A subtle, but consistent, genome-scale response to hypogravity environments was found, which was opposite to the response in a hypergravity environment. PMID:22435851

A multimodal assessment of driving performance in HIV infection.

PubMed

Marcotte, T D; Wolfson, T; Rosenthal, T J; Heaton, R K; Gonzalez, R; Ellis, R J; Grant, I

2004-10-26

To examine if HIV-seropositive (HIV+) individuals are at risk for impaired driving. Sixty licensed drivers (40 HIV+, 20 HIV-) completed a neuropsychological (NP) test battery and driving assessments. Eleven HIV+ subjects were NP-impaired. Driving-related skills were assessed using 1) two driving simulations (examining accident avoidance and navigational abilities), 2) the Useful Field of View (UFOV) test, and 3) an on-road evaluation. HIV+ NP-impaired subjects had greater difficulty than cognitively intact subjects on all driving measures, whereas the HIV- and HIV+ NP-normal groups performed similarly. On the UFOV, the HIV+ NP-impaired group had worse performance on Visual Processing and Divided Attention tasks but not in overall risk classification. They also had a higher number of simulator accidents (1.3 vs 2.0; p = 0.03), were less efficient at completing the navigation task (3.2 vs 9.2 blocks; p = 0.001), and were more likely to fail the on-road evaluation (6 vs 36%; p = 0.02). Impairment in Executive Functioning was the strongest NP predictor of failing the on-road drive test. NP performance and both simulations independently contributed to a model predicting 48% of the variance in on-road performance. HIV+ NP-impaired individuals are at increased risk for on-road driving impairments, whereas HIV+ individuals with normal cognition are not at a significantly higher risk than HIV- subjects. Executive Functioning is most strongly associated with impaired on-road performance. Cognitive and simulator testing may each provide data in identifying driving-impaired individuals.

Studies Toward Birth and Early Mammalian Development in Space

NASA Technical Reports Server (NTRS)

Ronca, April E.; Dalton, Bonnie (Technical Monitor)

2002-01-01

Successful reproduction is the hallmark of a species' ability to adapt to its environment and must be realized to sustain life beyond Earth. Before taking this immense step, we need to understand the effects of altered gravity on critical phases of mammalian reproduction, viz., those events surrounding pregnancy, birth and the early development of offspring. No mammal has yet undergone birth in space. however studies spanning the gravity continuum from 0 to 2-g are revealing insights into how birth and early postnatal development will proceed in space. In this presentation, I will report the results of behavioral studies of rat mothers and offspring exposed from mid- to late pregnancy to either hypogravity (0-g) or hypergravity (1.5 or 2-g).

Hormonal regulation of fluid and electrolytes during prolonged bed rest - Implications for microgravity

NASA Technical Reports Server (NTRS)

Greenleaf, John E.

1989-01-01

The results of studies on the physiological changes of body fluids and electrolytes during bed rest with and without exercise training are overviewed to determine the effect of exercise and to assess the role of hormonal regulation in fluid-electrolyte responses to hypogravity. Special attention is given to fluid shifts observed in spacecraft personnel during space missions. It is concluded that, despite an apparent uncoupling of prominent hormonal interactions during bed-rest deconditioning (and, possibly, during microgravity), the exercise-training-induced hypervolemia helps to counter the hypohydrostatic-induced dehydration. Thus, it was found that, after nearly a year of spaceflight during which one cosmonaut exercised for about 4 hr per day, the water balance and physiological functioning were not disturbed significantly.

A proposal to determine properties of the gravitropic response of plants in the absence of a complicating g-force (GTHRES)

NASA Technical Reports Server (NTRS)

Brown, Allan H.; Chapman, David K.; Heathcote, David G.; Johnsson, Anders

1993-01-01

Gravitropic responses of oat seedlings (Avena sativa L.) were measured on Earth and in microgravity (IML-1). The seedlings were grown at 1 g either on Earth or on 1 g centrifuges. They were challenged by centripetal accelerations for which the intensity and duration of the stimulations were varied. All stimulation intensities were in the hypogravity region from 0.1 to 1.0 g. All responses occurred either in Spacelab microgravity or during clinorotation on Earth. The experiments were carried out with the same apparatus in Spacelab and on Earth. The experiments addressed a series of scientific questions and useful data were obtained to provide answers to some but not all of those questions.

Human Health and Performance Aspects of the Mars Design Reference Mission

NASA Technical Reports Server (NTRS)

Charles, John B.

2000-01-01

This paper will describe the current planning for exploration-class missions, emphasizing the medical, and human factors aspects of such expeditions. The details of mission architecture are still under study, but a typical Mars design reference mission comprises a six-month transit from Earth to Mar, eighteen months in residence on Mars, and a six-month transit back to Earth. Physiological stressors will include environmental factors such as prolonged exposure to radiation, weightlessness in transit, and hypogravity and a toxic atmosphere while on Mars. Psychological stressors will include remoteness from Earth, confinement, and potential interpersonal conflicts, all complicated by circadian alterations. Medical risks including trauma must also be considered. Results of planning for assuring human health and performance will be presented.

Susceptibility of functional impairment scales to noncredible responses in the clinical evaluation of adult ADHD.

PubMed

Fuermaier, Anselm B M; Tucha, Oliver; Koerts, Janneke; Butzbach, Marah; Weisbrod, Matthias; Aschenbrenner, Steffen; Tucha, Lara

2018-05-01

A growing body of research questions the reliance of symptom self-reports in the clinical evaluation of attention-deficit/hyperactivity disorder (ADHD) in adulthood. A recent study suggested that also impairment reports are vulnerable to noncredible responses, as derived from a simulation design using a global functional impairment scale. The present study aims to add evidence to this issue, by using an ADHD specific impairment scale in a simulation design on large samples. Impairment ratings on the Weiss Functional Impairment Rating Scale (WFIRS) of 62 patients with ADHD were compared to 142 healthy individuals who were instructed to show normal behavior. Furthermore, impairment ratings of patients with ADHD were compared to ratings of 330 healthy individuals who were randomly assigned to one of four simulation conditions that were instructed to complete the scale as if they had ADHD. Patients with ADHD reported higher levels of impairment than the healthy control group in all domains of life. Furthermore, individuals instructed to feign ADHD indicated higher levels of impairments in most domains of life compared to control participants and genuine patients with ADHD. The group differences between individuals feigning ADHD and individuals with genuine ADHD, however, were only small to moderate. Further analyses revealed that the WFRIS was not useful to successfully differentiate genuine from feigned ADHD. The present study confirms the conclusion that self-reported impairments are susceptible to noncredible responses and should be used with caution in the clinical evaluation of adult ADHD.

Importance of eccentric actions in performance adaptations to resistance training

NASA Technical Reports Server (NTRS)

Dudley, Gary A.; Miller, Bruce J.; Buchanan, Paul; Tesch, Per A.

1991-01-01

The importance of eccentric (ecc) muscle actions in resistance training for the maintenance of muscle strength and mass in hypogravity was investigated in experiments in which human subjects, divided into three groups, were asked to perform four-five sets of 6 to 12 repetitions (rep) per set of three leg press and leg extension exercises, 2 days each weeks for 19 weeks. One group, labeled 'con', performed each rep with only concentric (con) actions, while group con/ecc with performed each rep with only ecc actions; the third group, con/con, performed twice as many sets with only con actions. Control subjects did not train. It was found that resistance training wih both con and ecc actions induced greater increases in muscle strength than did training with only con actions.

Research on the adaptation of skeletal muscle to hypogravity Past and future directions

NASA Technical Reports Server (NTRS)

Riley, D. A.; Ellis, S.

1983-01-01

The results of previous research on the cellular effects of microgravity on rat tissue are reviewed and areas of future necessary research are identified. The rats were flown on board Cosmos 605, 782, and 936. Postflight tissue analyses revealed increases in connective tissue cells and focal disruption of muscle fibers due to the microgravity environment of space. Evidence has been found for muscular and neural changes occurring as a result of reentry stresses. It is suggested that a data base be established for quantizing muscle function with electromyography, measurements of force output, and length measurement. The data can serve as a reference for comparisons with data obtained in orbiting laboratories such as the Spacelab. The experiments will have a goal of defining and preventing the mechanism of neuromuscular atrophy.

Life sciences and space research XXI(2); Proceedings of the Seventh and Eleventh Workshops, Graz, Austria, June 25-July 7, 1984

NASA Technical Reports Server (NTRS)

Oser, H. (Editor); Oro, J. (Editor); Macelroy, R. D. (Editor); Klein, H. P. (Editor); Devincenzi, D. L. (Editor); Young, R. S. (Editor)

1984-01-01

Space-based and space-related research in the life sciences is presented in reviews and reports. Topics examined include the long-term effects of weightlessness, cosmic chemistry and chemical and biological evolution, life-support systems for space travel, planetary protection, and the g-scale factor in gravitational biology. Consideration is given to the role of Ca ions in cytological effects of hypogravity, the organic aerosols of Titan, the role of meteorite impacts in the formation of organic molecules, prebiotic synthesis of purines and pyrimidines, atmosphere behavior of gas-closed mouse-algal systems, air and water regeneration in advanced regenerative environmental-control and life-support systems, and the influence of gravity on the development of animal systems.

Anxiety, Sedation, and Simulated Driving in Binge Drinkers

PubMed Central

Aston, Elizabeth R.; Shannon, Erin E.; Liguori, Anthony

2014-01-01

The current study evaluated the relationships among trait anxiety, subjective response to alcohol, and simulated driving following a simulated alcohol binge. Sixty drinkers with a binge history completed the State Trait Anxiety Inventory (STAI), the Alcohol Use Questionnaire, and subsequently completed a driving simulation. Participants were then administered 0.2 g/kg ethanol at 30 minute intervals (cumulative dose 0.8 g/kg). Following alcohol consumption, the Biphasic Alcohol Effects Scale (BAES) and visual analog scales of subjective impairment and driving confidence were administered, after which simulated driving was re-assessed. Due to the emphasis on simulated driving after drinking in the current study, subjective response to alcohol (i.e., self-reported sedation, stimulation, impairment, and confidence in driving ability) was assessed once following alcohol consumption, as this is the time when drinkers tend to make decisions regarding legal driving ability. Alcohol increased driving speed, speeding tickets, and collisions. Sedation following alcohol predicted increased subjective impairment and decreased driving confidence. Subjective impairment was not predicted by sensitivity to stimulation or trait anxiety. High trait anxiety predicted low driving confidence after drinking and this relationship was mediated by sedation. Increased speed after alcohol was predicted by sedation, but not by trait anxiety or stimulation. Anxiety, combined with the sedating effects of alcohol, may indicate when consumption should cease. However, once driving is initiated, sensitivity to sedation following alcohol consumption is positively related to simulated driving speed. PMID:24955664

The 48-Pictures Test: a two-alternative forced-choice recognition test for the detection of malingering.

PubMed

Chouinard, M J; Rouleau, I

1997-11-01

We tested the validity of the 48-Pictures Test, a 2-alternative forced-choice recognition test, in detecting exaggerated memory impairments. This test maximizes subjective difficulty, through a large number of stimuli and shows minimal objective difficulty. We compared 17 suspected malingerers to 39 patients with memory impairments (6 amnesic, 15 frontal lobe dysfunctions, 18 other etiologies), and 17 normal adults instructed to simulate malingering on three memory tests: the 48-Pictures Test, the Rey Auditory Verbal Learning Test (RAVLT), and the Rey Complex Figure Test (RCFT). On the 48-Pictures Test, the clinical groups showed good recognition performance (amnesics: 85%; frontal dysfunction: 94%; other memory impairments: 97%), whereas the two simulator groups showed a poor performance (suspected malingerers: 62% correct; volunteer simulators 68% correct). The two other tests did not show a high degree of discrimination between the clinical groups and the simulator groups, except in 2 measures: the 2 simulator groups tended to show a performance decrement from the last recall trial to immediate recognition of the RAVLT and also performed better than the clinical groups on the immediate recall of the RCFT. A discriminant analysis with the latter 2 measures and the 48-Pictures Test correctly classified 96% of the participants. These results suggest that the 48-Pictures Test is a useful tool for the detection of possible simulated memory impairment and that when combined to the RAVLT recall-recognition difference score and to the immediate recall score on the RCFT can provide strong evidence of exaggerated memory impairment.

Space agriculture in micro- and hypo-gravity: A comparative study of soil hydraulics and biogeochemistry in a cropping unit on Earth, Mars, the Moon and the space station

NASA Astrophysics Data System (ADS)

Maggi, Federico; Pallud, Céline

2010-12-01

Increasing interest is developing towards soil-based agriculture as a long-term bioregenerative life support during space and planetary explorations. Contrary to hydroponics and aeroponics, soil-based cropping would offer an effective approach to sustain food and oxygen production, decompose organic wastes, sequester carbon dioxide, and filter water. However, the hydraulics and biogeochemical functioning of soil systems exposed to gravities lower than the Earth's are still unknown. Since gravity is crucial in driving water flow, hypogravity will affect nutrient and oxygen transport in the liquid and gaseous phases, and could lead to suffocation of microorganisms and roots, and emissions of toxic gases. A highly mechanistic model coupling soil hydraulics and nutrient biogeochemistry previously tested on soils on Earth ( g=9.806 m s -2) is used to highlight the effects of gravity on the functioning of cropping units on Mars (0.38 g), the Moon (0.16 g), and in the international space station (ISS, nearly 0 g). For each scenario, we have compared the net leaching of water, the leaching of NH 3, NH 4+, NO 2- and NO 3- solutes, the emissions of NH 3, CO 2, N 2O, NO and N 2 gases, the concentrations profiles of O 2, CO 2 and dissolved organic carbon (DOC) in soil, the pH, and the dynamics of various microbial functional groups within the root zone against the same control variables in the soil under terrestrial gravity. The response of the soil ecodynamics was relatively linear; gravitational accelerations lower than the Earth's resulted in 90-100% lower water leaching rates, 95-100% lower nutrient leaching rates, and lower emissions of NH 3 and NO gases (80-95% and 30-40%, respectively). Lower N loss through leaching resulted in 60-100% higher concentration of the microbial biomass, but did not alter the vertical stratification of the microbial functional groups with respect to the stratification on Earth. However, the higher biomass concentration produced higher emissions of N 2O, N 2, and CO 2 gases (80%, 200% and 40%, respectively).

Alcohol Effects on Simulated Driving in Frequent and Infrequent Binge Drinkers

PubMed Central

Bernosky-Smith, Kimberly A.; Shannon, Erin E.; Roth, Alicia J.; Liguori, Anthony

2011-01-01

Objective Compared to non-bingers, binge drinkers are more likely to drive while intoxicated. The extent to which binge frequency impacts confidence in driving and subsequent driving impairment is unknown. This study compared the effects of an experimenter-delivered alcohol binge on subjective impairment and simulated driving ability in female High and Low Frequency bingers. Methods Female drinkers were assigned to High Frequency (n=30) or Low Frequency (n=30) binge groups based on their Alcohol Use Questionnaire responses. At 30-minute intervals within a two-hour period, participants received either a placebo drink (n=15 per group) or a 0.2 g/kg dose of alcohol (n=15 per group; cumulative dose 0.8 g/kg). Self-reported impairment, driving confidence, and simulated driving were then measured. Results Self-reported confidence in driving was significantly lower after alcohol than after placebo in Low Frequency but not High Frequency bingers. Self-reported impairment and collisions during simulated driving were significantly greater after alcohol than after placebo in both Low Frequency and High Frequency bingers. Conclusions The impairing effects of a single alcohol binge on driving ability in females are not influenced by binge frequency. However, high binge frequency may be associated with a less cautious approach to post-binge driving. PMID:21542027

The Level of Vision Necessary for Competitive Performance in Rifle Shooting: Setting the Standards for Paralympic Shooting with Vision Impairment.

PubMed

Allen, Peter M; Latham, Keziah; Mann, David L; Ravensbergen, Rianne H J C; Myint, Joy

2016-01-01

The aim of this study was to investigate the level of vision impairment (VI) that would reduce performance in shooting; to guide development of entry criteria to visually impaired (VI) shooting. Nineteen international-level shooters without VI took part in the study. Participants shot an air rifle, while standing, toward a regulation target placed at the end of a 10 m shooting range. Cambridge simulation glasses were used to simulate six different levels of VI. Visual acuity (VA) and contrast sensitivity (CS) were assessed along with shooting performance in each of seven conditions of simulated impairment and compared to that with habitual vision. Shooting performance was evaluated by calculating each individual's average score in every level of simulated VI and normalizing this score by expressing it as a percentage of the baseline performance achieved with habitual vision. Receiver Operating Characteristic curves were constructed to evaluate the ability of different VA and CS cut-off criteria to appropriately classify these athletes as achieving 'expected' or 'below expected' shooting results based on their performance with different levels of VA and CS. Shooting performance remained relatively unaffected by mild decreases in VA and CS, but quickly deteriorated with more moderate losses. The ability of visual function measurements to classify shooting performance was good, with 78% of performances appropriately classified using a cut-off of 0.53 logMAR and 74% appropriately classified using a cut-off of 0.83 logCS. The current inclusion criteria for VI shooting (1.0 logMAR) is conservative, maximizing the chance of including only those with an impairment that does impact performance, but potentially excluding some who do have a genuine impairment in the sport. A lower level of impairment would include more athletes who do have a genuine impairment but would potentially include those who do not actually have an impairment that impacts performance in the sport. An impairment to CS could impact performance in the sport and might be considered in determining eligibility to take part in VI competition.

The Level of Vision Necessary for Competitive Performance in Rifle Shooting: Setting the Standards for Paralympic Shooting with Vision Impairment

PubMed Central

Allen, Peter M.; Latham, Keziah; Mann, David L.; Ravensbergen, Rianne H. J. C.; Myint, Joy

2016-01-01

The aim of this study was to investigate the level of vision impairment (VI) that would reduce performance in shooting; to guide development of entry criteria to visually impaired (VI) shooting. Nineteen international-level shooters without VI took part in the study. Participants shot an air rifle, while standing, toward a regulation target placed at the end of a 10 m shooting range. Cambridge simulation glasses were used to simulate six different levels of VI. Visual acuity (VA) and contrast sensitivity (CS) were assessed along with shooting performance in each of seven conditions of simulated impairment and compared to that with habitual vision. Shooting performance was evaluated by calculating each individual’s average score in every level of simulated VI and normalizing this score by expressing it as a percentage of the baseline performance achieved with habitual vision. Receiver Operating Characteristic curves were constructed to evaluate the ability of different VA and CS cut-off criteria to appropriately classify these athletes as achieving ‘expected’ or ‘below expected’ shooting results based on their performance with different levels of VA and CS. Shooting performance remained relatively unaffected by mild decreases in VA and CS, but quickly deteriorated with more moderate losses. The ability of visual function measurements to classify shooting performance was good, with 78% of performances appropriately classified using a cut-off of 0.53 logMAR and 74% appropriately classified using a cut-off of 0.83 logCS. The current inclusion criteria for VI shooting (1.0 logMAR) is conservative, maximizing the chance of including only those with an impairment that does impact performance, but potentially excluding some who do have a genuine impairment in the sport. A lower level of impairment would include more athletes who do have a genuine impairment but would potentially include those who do not actually have an impairment that impacts performance in the sport. An impairment to CS could impact performance in the sport and might be considered in determining eligibility to take part in VI competition. PMID:27877150

Effect of Mental Arithmetic on heart rate responses during Parabolic Flights: the Barcelona Zero-G Challenge

NASA Astrophysics Data System (ADS)

Osborne, Jeffrey R.; Alonsopérez Lanza, María Victoria; Desclaux, David Ferrer; Goswami, Nandu; González Alonso, Daniel Ventura; Moser, Maximilian; Grote, Vincent; Garcia-Cuadrado, Gloria; Perez-Poch, Antoni

2014-07-01

When an astronaut transitions from a low to high gravitational environment, fluid shifts from the head towards the feet resulting in orthostatic intolerance and syncope. Ground based experiments have shown that by stimulating the cardiovascular system via simple mental stressors, syncope can be delayed, potentially enabling astronauts to reach assistance before loss of consciousness. However, the effect of mental stressors on the stimulation of the cardiovascular system in gravitational environments different than that of Earth's is unknown. As such, this paper investigates the effects that mental stressors under various gravitational environments. To do this, a pilot study was performed in which two participants were flown on two separate parabolic flights that simulated hyper and hypogravity conditions. The plane used was an Aerobatic Single-Engine Cap-10B plane (twin seater), and each participant executed 11 parabolas. The participants were the winners of the Barcelona Zero-G Challenge 2011 organized by UPC Universitat Politècnica de Catalunya-BarcelonaTech and Aeroclub Barcelona-Sabadell. Measurements were made of the participants' hemodynamic and autonomic response throughout the parabolas, using a Chronocord: high precision HRV monitor. Comparisons of the baseline response without mental stressors, and the response with mental stressors during different gravitational loading conditions were made. It was observed that there is an increase in cardiovascular activity during hypo- and hyper-gravity when performing mental arithmetic. Our results show that the twin seater aerobatic single engine CAP-10B aicraft can provide changing gravitational loading conditions for enough periods to study changes in physiological systems.

Contributions of muscle imbalance and impaired growth to postural and osseous shoulder deformity following brachial plexus birth palsy: a computational simulation analysis.

PubMed

Cheng, Wei; Cornwall, Roger; Crouch, Dustin L; Li, Zhongyu; Saul, Katherine R

2015-06-01

Two potential mechanisms leading to postural and osseous shoulder deformity after brachial plexus birth palsy are muscle imbalance between functioning internal rotators and paralyzed external rotators and impaired longitudinal growth of paralyzed muscles. Our goal was to evaluate the combined and isolated effects of these 2 mechanisms on transverse plane shoulder forces using a computational model of C5-6 brachial plexus injury. We modeled a C5-6 injury using a computational musculoskeletal upper limb model. Muscles expected to be denervated by C5-6 injury were classified as affected, with the remaining shoulder muscles classified as unaffected. To model muscle imbalance, affected muscles were given no resting tone whereas unaffected muscles were given resting tone at 30% of maximal activation. To model impaired growth, affected muscles were reduced in length by 30% compared with normal whereas unaffected muscles remained normal in length. Four scenarios were simulated: normal, muscle imbalance only, impaired growth only, and both muscle imbalance and impaired growth. Passive shoulder rotation range of motion and glenohumeral joint reaction forces were evaluated to assess postural and osseous deformity. All impaired scenarios exhibited restricted range of motion and increased and posteriorly directed compressive glenohumeral joint forces. Individually, impaired muscle growth caused worse restriction in range of motion and higher and more posteriorly directed glenohumeral forces than did muscle imbalance. Combined muscle imbalance and impaired growth caused the most restricted joint range of motion and the highest joint reaction force of all scenarios. Both muscle imbalance and impaired longitudinal growth contributed to range of motion and force changes consistent with clinically observed deformity, although the most substantial effects resulted from impaired muscle growth. Simulations suggest that treatment strategies emphasizing treatment of impaired longitudinal growth are warranted for reducing deformity after brachial plexus birth palsy. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Transient immune impairment after a simulated long-haul flight.

PubMed

Wilder-Smith, Annelies; Mustafa, Fatima B; Peng, Chung Mien; Earnest, Arul; Koh, David; Lin, Gen; Hossain, Iqbal; MacAry, Paul A

2012-04-01

Almost 2 billion people travel aboard commercial airlines every year, with about 20% developing symptoms of the common cold within 1 wk after air travel. We hypothesize that hypobaric hypoxic conditions associated with air travel may contribute to immune impairment. We studied the effects of hypobaric hypoxic conditions during a simulated flight at 8000 ft (2438 m) cruising altitude on immune and stress markers in 52 healthy volunteers (mean age 31) before and on days 1, 4, and 7 after the flight. We did a cohort study using a generalized estimating equation to examine the differences in the repeated measures. Our findings show that the hypobaric hypoxic conditions of a 10-h overnight simulation flight are not associated with severe immune impairment or abnormal IgA or cortisol levels, but with transient impairment in some parameters: we observed a transient decrease in lymphocyte proliferative responses combined with an upregulation in CD69 and CD14 cells and a decrease in HLA-DR in the immediate days following the simulated flight that normalized by day 7 in most instances. These transient immune changes may contribute to an increased susceptibility to respiratory infections commonly seen after long-haul flights.

Gravitropic responses of plants in the absence of a complicating G-force (6-IML-1)

NASA Technical Reports Server (NTRS)

Brown, Allan H.

1992-01-01

On the Earth it is patently impossible to measure any tropistic, physiologic, or morphogenic reactions to environmental stimuli without taking into account our planet's gravitational influence on the time course of the test subject's response. It follows that all published reports of quantitative measurements of such responses must have been contaminated by an additional gravity dependent component which probably was not trivial. Our research effort has as its principal scientific objective, the acquisition of experimental data from tests in a microgravity environment that will address a number of basic questions about plants' gravitropic responses to the perception of transversely applied g forces in the hypogravity range, from essentially zero to unit g. Comparable tests on Earth but in the same flight hardware, referred to as the Gravitational Plant Physiology Facility (GPPF), will provide 1 g data for various useful comparisons. Four specific scientific questions are addressed.

Operation of magnetically assisted fluidized beds in microgravity and variable gravity: experiment and theory

NASA Technical Reports Server (NTRS)

Sornchamni, T.; Jovanovic, G. N.; Reed, B. P.; Atwater, J. E.; Akse, J. R.; Wheeler, R. R.

2004-01-01

The conversion of solid waste into useful resources in support of long duration manned missions in space presents serious technological challenges. Several technologies, including supercritical water oxidation, microwave powered combustion and fluidized bed incineration, have been tested for the conversion of solid waste. However, none of these technologies are compatible with microgravity or hypogravity operating conditions. In this paper, we present the gradient magnetically assisted fluidized bed (G-MAFB) as a promising operating platform for fluidized bed operations in the space environment. Our experimental and theoretical work has resulted in both the development of a theoretical model based on fundamental principles for the design of the G-MAFB, and also the practical implementation of the G-MAFB in the filtration and destruction of solid biomass waste particles from liquid streams. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

Motion sickness elicited by passive rotation in squirrel monkeys

NASA Technical Reports Server (NTRS)

Daunton, Nancy G.; Fox, Robert A.

1991-01-01

Current theory and recent evidence suggest that motion sickness occurs under conditions of sensory input in which the normal motor programs for producing eye, head, and body movements are not functionally effective, i.e. under conditions in which there are difficulties in maintaining posture and controlling eye movements. Conditions involving conflicting or inconsistent visual-vestibular (VV) stimulation should thus result in greater sickness rates since the existing motor programs do not produce effective control of eye-head-body movements under such conditions. It is felt that the relationship of postural control to motion sickness is an important one and one often overlooked. The results are reported which showed that when postural requirements were minimized by fully restraining squirrel monkeys during hypogravity parabolic flight, no animals became motion sick, but over 80 percent of the same 11 animals became sick if they were unrestrained and maintained control of their posture.

Morphological and biochemical changes in soleus and extensor digitorum longus muscles of rats orbited in Spacelab 3

NASA Technical Reports Server (NTRS)

Riley, D. A.; Slocum, T.; Bain, J. L. W.; Sedlak, F. R.; Elis, S.; Satyanarayana, T.

1985-01-01

Muscle atrophy in rats exposed to hypogravity for seven days aboard Spacelab 3 is examined. Hindlimb muscles were harvested 12-16 days postflight, and prepared for enzyme studies and electron microscopy. Simple cell shrinkage was found, with a mean fiber area decrease of 35.8 percent for soleus and 24.9 percent for extensor digitorum longus (EDL) flight muscle fibers, as compared with control muscle fibers. EDL and soleus muscles showed increases in alkaline myofibrillar ATPase, alpha glycerophosphate dehydrogenase, and glycogen, and a decrease in NADH dehydrogenase staining. The 26 percent increase in calcium activated protease suggests that the focal degradation of myofibrils is the key process of myofibril breakdown. The presence in the flight soleus muscles of one percent necrotic fibers is unexplained. The observed shift towards histochemical fast-muscle type properties is consistent with previous findings.

Using Simulations To Understand Older Adults with Sensory Impairment.

ERIC Educational Resources Information Center

Clubok, Miriam

2000-01-01

Summarizes two popular models for increasing sensitivity to sensory impairment in the elderly and details a third model used in training human service students and practitioners. Ideas and techniques presented work toward understanding the impact of sensory impairment on the daily life of older adults and to identify coping techniques to improve…

Immunohistochemical study of motoneurons in lumbar spinal cord of c57black/6 mice after 30-days space flight

NASA Astrophysics Data System (ADS)

Tyapkina, Oksana; Islamov, Rustem; Nurullin, Leniz; Petrov, Konstantin.; Rezvyakov, Pavel; Nikolsky, Evgeny

To investigate mechanisms of hypogravity motor syndrome development the immunoexpression of heat shock proteins (Hsp27 and Hsp70), proteins of synaptic transmission (Synaptophysin and PSD95) and neuroprotective proteins (VEGF and Flt-1) in motoneurons of lumbar spinal cord in c57black/6 control mice (n=2) and after 30-days space flight (n=2) was studied. For a quantitative assessment of target proteins level in motoneurons frozen cross sections of lumbar spinal cord were underwent to immunohistochemical staining. Primary antibodies against VEGF, Flt-1, Hsp27 and Hsp70 (SantaCruz Biotechnology, inc. USA), against Synaptophysin and PSD95 (Abcam plc, UK) were visualized by streptavidin-biotin method. Images of spinal cords were received using OlympusBX51WI microscope with AxioCamMRm camera (CarlZeiss, Germany) and the AxioVisionRel. 4.6.3 software (CarlZeiss, Germany). The digitized data were analyzed using ImageJ 1.43 software (NIH, the USA). Quantitively, protein level in motoneurons was estimated by the density of immunoprecipitation. Results of research have not revealed any reliable changes in the immunnoexpression of vascular endothelial growth factor (VEGF) and its Flt-1 receptor in motoneurons of lumbar spinal cord in control and in mice after 30-day space flight. Studying of heat shock proteins, such as Hsp27 and Hsp70, revealed the decrease in level of these proteins immunoexpression in motoneurons of mice from flight group by 15% and 10%, respectively. Some decrease in level of immunnoexpression of presynaptic membrane proteins (synaptophysin, by 21%) and proteins of postsynaptic area (PSD95, by 55%) was observed after space flight. The data obtained testify to possible changes in a functional state (synaptic activity and stress resistance) of motoneurons of lumbar spinal cord in mice after space flight. Thus, we obtained new data on involvement of motoneurons innervating skeletal muscles in development of hypogravity motor syndrome. Research was supported by grants of: BION-M1, program of the President of the Russian Federation (Science School) no. No. 5584.214.4 (NEE), RFFR No.11-04-00602 (NEE), Program No.7 of Presidium of RAS (NEE), RFFR No.13-04-00310 (IRR), RFFR No.12-04-01414 (NLF).

Dual-task effects of simulated lane navigation and story recall in older adults with and without memory impairment

PubMed Central

Cook, Sarah E.; Sisco, Shannon M.; Marsiske, Michael

2013-01-01

While driving is a complex task, it becomes relatively automatic over time although unfamiliar situations require increased cognitive effort. Much research has examined driving risk in cognitively impaired elders and found little effect. This study assessed whether mildly memory impaired elders made disproportionate errors in driving or story recall, under simultaneous simulated driving and story recall. Forty-six healthy (61% women; mean age = 76.4) and 15 memory impaired (66% women, mean age = 79.4) elders participated. Cognitive status was determined by neuropsychological performance. Results showed that during dual-task conditions, participants stayed in lane more, and recalled stories more poorly, than when they did the tasks separately. Follow-up analysis revealed that verbatim recall, in particular, was reduced while driving for healthy participants. While memory impaired participants performed more poorly than healthy controls on both tasks, cognitive status was not associated with greater dual-task costs when driving and story recall were combined. PMID:23043546

Dual-task effects of simulated lane navigation and story recall in older adults with and without memory impairment.

PubMed

Cook, Sarah E; Sisco, Shannon M; Marsiske, Michael

2013-01-01

While driving is a complex task, it becomes relatively automatic over time although unfamiliar situations require increased cognitive effort. Much research has examined driving risk in cognitively impaired elders and found little effect. This study assessed whether mildly memory impaired elders made disproportionate errors in driving or story recall, under simultaneous simulated driving and story recall. Forty-six healthy (61% women; mean age = 76.4) and 15 memory impaired (66% women, mean age = 79.4) elders participated. Cognitive status was determined by neuropsychological performance. Results showed that during dual-task conditions, participants stayed in lane more, and recalled stories more poorly, than when they did the tasks separately. Follow-up analysis revealed that verbatim recall, in particular, was reduced while driving for healthy participants. While memory impaired participants performed more poorly than healthy controls on both tasks, cognitive status was not associated with greater dual-task costs when driving and story recall were combined.

The effects of elevated hearing thresholds on performance in a paintball simulation of individual dismounted combat.

PubMed

Sheffield, Benjamin; Brungart, Douglas; Tufts, Jennifer; Ness, James

2017-01-01

To examine the relationship between hearing acuity and operational performance in simulated dismounted combat. Individuals wearing hearing loss simulation systems competed in a paintball-based exercise where the objective was to be the last player remaining. Four hearing loss profiles were tested in each round (no hearing loss, mild, moderate and severe) and four rounds were played to make up a match. This allowed counterbalancing of simulated hearing loss across participants. Forty-three participants across two data collection sites (Fort Detrick, Maryland and the United States Military Academy, New York). All participants self-reported normal hearing except for two who reported mild hearing loss. Impaired hearing had a greater impact on the offensive capabilities of participants than it did on their "survival", likely due to the tendency for individuals with simulated impairment to adopt a more conservative behavioural strategy than those with normal hearing. These preliminary results provide valuable insights into the impact of impaired hearing on combat effectiveness, with implications for the development of improved auditory fitness-for-duty standards, the establishment of performance requirements for hearing protection technologies, and the refinement of strategies to train military personnel on how to use hearing protection in combat environments.

Are Hemianopic Reading and Visual Exploration Impairments Visually Elicited? New Insights from Eye Movements in Simulated Hemianopia

ERIC Educational Resources Information Center

Schuett, Susanne; Kentridge, Robert W.; Zihl, Josef; Heywood, Charles A.

2009-01-01

Hemianopic reading and visual exploration impairments are well-known clinical phenomena. Yet, it is unclear whether they are primarily caused by the hemianopic visual field defect itself or by additional brain injury preventing efficient spontaneous oculomotor adaptation. To establish the extent to which these impairments are visually elicited we…

Investigating Simulated Driving Errors in Amnestic Single- and Multiple-Domain Mild Cognitive Impairment.

PubMed

Hird, Megan A; Vesely, Kristin A; Fischer, Corinne E; Graham, Simon J; Naglie, Gary; Schweizer, Tom A

2017-01-01

The areas of driving impairment characteristic of mild cognitive impairment (MCI) remain unclear. This study compared the simulated driving performance of 24 individuals with MCI, including amnestic single-domain (sd-MCI, n = 11) and amnestic multiple-domain MCI (md-MCI, n = 13), and 20 age-matched controls. Individuals with MCI committed over twice as many driving errors (20.0 versus 9.9), demonstrated difficulty with lane maintenance, and committed more errors during left turns with traffic compared to healthy controls. Specifically, individuals with md-MCI demonstrated greater driving difficulty compared to healthy controls, relative to those with sd-MCI. Differentiating between different subtypes of MCI may be important when evaluating driving safety.

Episodic simulation of future events is impaired in mild Alzheimer's disease

PubMed Central

Addis, Donna Rose; Sacchetti, Daniel C.; Ally, Brandon A.; Budson, Andrew E.; Schacter, Daniel L.

2009-01-01

Recent neuroimaging studies have demonstrated that both remembering the past and simulating the future activate a core neural network including the medial temporal lobes. Regions of this network, in particular the medial temporal lobes, are prime sites for amyloid deposition and are structurally and functionally compromised in Alzheimer's disease (AD). While we know some functions of this core network, specifically episodic autobiographical memory, are impaired in AD, no study has examined whether future episodic simulation is similarly impaired. We tested the ability of sixteen AD patients and sixteen age-matched controls to generate past and future autobiographical events using an adapted version of the Autobiographical Interview. Participants also generated five remote autobiographical memories from across the lifespan. Event transcriptions were segmented into distinct details, classified as either internal (episodic) or external (non-episodic). AD patients exhibited deficits in both remembering past events and simulating future events, generating fewer internal and external episodic details than healthy older controls. The internal and external detail scores were strongly correlated across past and future events, providing further evidence of the close linkages between the mental representations of past and future. PMID:19497331

Gravitropic responses of the Avena coleoptile in space and on clinostats. II. Is reciprocity valid?

NASA Technical Reports Server (NTRS)

Johnsson, A.; Brown, A. H.; Chapman, D. K.; Heathcote, D.; Karlsson, C.

1995-01-01

Experiments were undertaken to determine if the reciprocity rule is valid for gravitropic responses of oat coleoptiles in the acceleration region below 1 g. The rule predicts that the gravitropic response should be proportional to the product of the applied acceleration and the stimulation time. Seedlings were cultivated on 1 g centrifuges and transferred to test centrifuges to apply a transverse g-stimulation. Since responses occurred in microgravity, the uncertainties about the validity of clinostat simulation of weightlessness was avoided. Plants at two stages of coleoptile development were tested. Plant responses were obtained using time-lapse video recordings that were analyzed after the flight. Stimulus intensities and durations were varied and ranged from 0.1 to 1.0 g and from 2 to 130 min, respectively. For threshold g-doses the reciprocity rule was obeyed. The threshold dose was of the order of 55 g s and 120 g s, respectively, for two groups of plants investigated. Reciprocity was studied also at bending responses which are from just above the detectable level to about 10 degrees. The validity of the rule could not be confirmed for higher g-doses, chiefly because the data were more variable. It was investigated whether the uniformity of the overall response data increased when the gravitropic dose was defined as (gm x t) with m-values different from unity. This was not the case and the reciprocity concept is, therefore, valid also in the hypogravity region. The concept of gravitropic dose, the product of the transverse acceleration and the stimulation time, is also well-defined in the acceleration region studied. With the same hardware, tests were done on earth where responses occurred on clinostats. The results did not contradict the reciprocity rule but scatter in the data was large.

A Standalone Vision Impairments Simulator for Java Swing Applications

NASA Astrophysics Data System (ADS)

Oikonomou, Theofanis; Votis, Konstantinos; Korn, Peter; Tzovaras, Dimitrios; Likothanasis, Spriridon

A lot of work has been done lately in an attempt to assess accessibility. For the case of web rich-client applications several tools exist that simulate how a vision impaired or colour-blind person would perceive this content. In this work we propose a simulation tool for non-web JavaTM Swing applications. Developers and designers face a real challenge when creating software that has to cope with a lot of interaction situations, as well as specific directives for ensuring an accessible interaction. The proposed standalone tool will assist them to explore user-centered design and important accessibility issues for their JavaTM Swing implementations.

The effects of simulated vision impairments on the cone of gaze.

PubMed

Hecht, Heiko; Hörichs, Jenny; Sheldon, Sarah; Quint, Jessilin; Bowers, Alex

2015-10-01

Detecting the gaze direction of others is critical for many social interactions. We explored factors that may make the perception of mutual gaze more difficult, including the degradation of the stimulus and simulated vision impairment. To what extent do these factors affect the complex assessment of mutual gaze? Using an interactive virtual head whose eye direction could be manipulated by the subject, we conducted two experiments to assess the effects of simulated vision impairments on mutual gaze. Healthy subjects had to demarcate the center and the edges of the cone of gaze-that is, the range of gaze directions that are accepted for mutual gaze. When vision was impaired by adding a semitransparent white contrast reduction mask to the display (Exp. 1), judgments became more variable and more influenced by the head direction (indicative of a compensation strategy). When refractive blur was added (Exp. 1), the gaze cone shrank from 12.9° (no blur) to 11.3° (3-diopter lens), which cannot be explained by a low-level process but might reflect a tightening of the criterion for mutual gaze as a response to the increased uncertainty. However, the overall effects of the impairments were relatively modest. Elderly subjects (Exp. 2) produced more variability but did not differ qualitatively from the younger subjects. In the face of artificial vision impairments, compensation mechanisms and criterion changes allow us to perform better in mutual gaze perception than would be predicted by a simple extrapolation from the losses in basic visual acuity and contrast sensitivity.

Driving difficulties of brain-injured drivers in reaction to high-crash-risk simulated road events: a question of impaired divided attention?

PubMed

Cyr, Andrée-Ann; Stinchcombe, Arne; Gagnon, Sylvain; Marshall, Shawn; Hing, Malcolm Man-Son; Finestone, Hillel

2009-05-01

This study examined the role of impaired divided attention and speed of processing in traumatic brain injury (TBI) drivers in high-crash-risk simulated road events. A total of 17 TBI drivers and 16 healthy participants were exposed to four challenging simulated roadway events to which behavioral reactions were recorded. Participants were also asked to perform a dual task during portions of the driving task, and TBI individuals were administered standard measures of divided attention and reaction time. Results indicated that the TBI group crashed significantly more than controls (p < .05) and that dual-task performance correlated significantly with crash rate (r = .58, p = .05).

Simulated Driving Performance of Adults with ADHD: Comparisons with Alcohol Intoxication

PubMed Central

Weafer, Jessica; Camarillo, Daniel; Fillmore, Mark T.; Milich, Richard; Marczinski, Cecile A.

2015-01-01

Previous research has demonstrated that adults with ADHD are more likely to experience driving-related problems, which suggests that they may exhibit poorer driving performance. However, direct experimental evidence of this hypothesis is limited. The current study involved two experiments that evaluated driving performance in adults with ADHD in terms of the types of driving decrements typically associated with alcohol intoxication. Experiment 1 compared the simulated driving performance of 15 adults with ADHD to 23 adult control participants, who performed the task both while sober and intoxicated. Results showed that sober adults with ADHD exhibited decrements in driving performance compared to sober controls, and that the profile of impairment for the sober ADHD group did in fact resemble that of intoxicated drivers at the BAC level for legally impaired driving in the United States. Driving impairment of the intoxicated individuals was characterized by greater deviation of lane position, faster and more abrupt steering maneuvers, and increased speed variability. Experiment 2 was a dose-challenge study in which 8 adults with ADHD and 8 controls performed the driving simulation task under three doses of alcohol: 0.65 g/kg, 0.45 g/kg, and 0.0 g/kg (placebo). Results showed that driving performance in both groups was impaired in response to alcohol, and that individuals with ADHD exhibited generally poorer driving performance than did controls across all dose conditions. Together the findings provide compelling evidence to suggest that the cognitive and behavioral deficits associated with ADHD might impair driving performance in such a manner as to resemble that of an alcohol intoxicated driver. Moreover, alcohol might impair the performance of drivers with ADHD in an additive fashion that could considerably compromise their driving skill even at blood alcohol concentrations below the legal limit. PMID:18540785

Biomechanical study on the bladder neck and urethral positions: simulation of impairment of the pelvic ligaments.

PubMed

Brandão, Sofia; Parente, Marco; Mascarenhas, Teresa; da Silva, Ana Rita Gomes; Ramos, Isabel; Jorge, Renato Natal

2015-01-21

Excessive mobility of the bladder neck and urethra are common features in stress urinary incontinence. We aimed at assessing, through computational modelling, the bladder neck position taking into account progressive impairment of the pelvic ligaments. Magnetic resonance images of a young healthy female were used to build a computational model of the pelvic cavity. Appropriate material properties and constitutive models were defined. The impairment of the ligaments was simulated by mimicking a reduction in their stiffness. For healthy ligaments, valsalva maneuver led to an increase in the α angle (between the bladder neck-symphysis pubis and the main of the symphysis) from 91.8° (at rest) to 105.7°, and 5.7 mm of bladder neck dislocation, which was similar to dynamic imaging of the same woman (α angle from 80° to 103.3°, and 5mm of bladder neck movement). For 95% impairment, they enlarged to 124.28° and 12 mm. Impairment to the pubourethral ligaments had higher effect than that of vaginal support (115° vs. 108°, and 9.1 vs. 7.3mm). Numerical simulation could predict urethral motion during valsalva maneuver, for both healthy and impaired ligaments. Results were similar to those of continent women and women with stress urinary incontinence published in the literature. Biomechanical analysis of the pubourethral ligaments complements the biomechanical study of the pelvic cavity in urinary incontinence. It may be useful in young women presenting stress urinary incontinence without imaging evidence of urethral and muscle lesions or organ descend during valsalva, and for whom fascial damage are not expected. Copyright © 2014 Elsevier Ltd. All rights reserved.

Navigation skill impairment: Another dimension of the driving difficulties in minimal hepatic encephalopathy.

PubMed

Bajaj, Jasmohan S; Hafeezullah, Muhammad; Hoffmann, Raymond G; Varma, Rajiv R; Franco, Jose; Binion, David G; Hammeke, Thomas A; Saeian, Kia

2008-02-01

Patients with minimal hepatic encephalopathy (MHE) have attention, response inhibition, and working memory difficulties that are associated with driving impairment and high motor vehicle accident risk. Navigation is a complex system needed for safe driving that requires functioning working memory and other domains adversely affected by MHE. The aim of this study was to determine the effect of MHE on navigation skills and correlate them with psychometric impairment. Forty-nine nonalcoholic patients with cirrhosis (34 MHE+, 15 MHE-; divided on the basis of a battery of block design, digit symbol, and number connection test A) and 48 age/education-matched controls were included. All patients underwent the psychometric battery and inhibitory control test (ICT) (a test of response inhibition) and driving simulation. Driving simulation consisted of 4 parts: (1) training; (2) driving (outcome being accidents); (3) divided attention (outcome being missed tasks); and (4) navigation, driving along a marked path on a map in a "virtual city" (outcome being illegal turns). Illegal turns were significantly higher in MHE+ (median 1; P = 0.007) compared with MHE-/controls (median 0). Patients who were MHE+ missed more divided attention tasks compared with others (median MHE+ 1, MHE-/controls 0; P = 0.001). Similarly, accidents were higher in patients who were MHE+ (median 2.5; P = 0.004) compared with MHE- (median 1) or controls (median 2). Accidents and illegal turns were significantly correlated (P = 0.001, r = 0.51). ICT impairment was the test most correlated with illegal turns (r = 0.6) and accidents (r = 0.44), although impairment on the other tests were also correlated with illegal turns. Patients positive for MHE have impaired navigation skills on a driving simulator, which is correlated with impairment in response inhibition (ICT) and attention. This navigation difficulty may pose additional driving problems, compounding the pre-existing deleterious effect of attention deficits.

Temporal modulation transfer functions for listeners with real and simulated hearing loss

PubMed Central

Desloge, Joseph G.; Reed, Charlotte M.; Braida, Louis D.; Perez, Zachary D.; Delhorne, Lorraine A.

2011-01-01

A functional simulation of hearing loss was evaluated in its ability to reproduce the temporal modulation transfer functions (TMTFs) for nine listeners with mild to profound sensorineural hearing loss. Each hearing loss was simulated in a group of three age-matched normal-hearing listeners through spectrally shaped masking noise or a combination of masking noise and multiband expansion. TMTFs were measured for both groups of listeners using a broadband noise carrier as a function of modulation rate in the range 2 to 1024 Hz. The TMTFs were fit with a lowpass filter function that provided estimates of overall modulation-depth sensitivity and modulation cutoff frequency. Although the simulations were capable of accurately reproducing the threshold elevations of the hearing-impaired listeners, they were not successful in reproducing the TMTFs. On average, the simulations resulted in lower sensitivity and higher cutoff frequency than were observed in the TMTFs of the hearing-impaired listeners. Discrepancies in performance between listeners with real and simulated hearing loss are possibly related to inaccuracies in the simulation of recruitment. PMID:21682411

The effect of coaching on the simulated malingering of memory impairment.

PubMed

Rüsseler, Jascha; Brett, Alexandra; Klaue, Ulrike; Sailer, Michael; Münte, Thomas F

2008-10-07

Detecting malingering or exaggeration of impairments in brain function after traumatic brain injury is of increasing importance in neuropsychological assessment. Lawyers involved in brain injury litigation cases routinely coach their clients how to approach neuropsychological testing to their advantage. Thus, it is important to know how robust assessment methods are with respect to symptom malingering or exaggeration. The influence of different coaching methods on the simulated malingering of memory impairments is investigated in neurologically healthy participants using the Short-Term-Memory Test from the Bremer Symptom-Validierung (STM-BSV). Cut-offs were derived from patients with mild to severe traumatic brain injury. For comparison purposes, the German adaptation of the Rey Auditory Verbal Learning Test (AVLT), and the Rey 15 Items Test (FIT) were additionally administered. Four groups of neurologically healthy subjects were instructed to (1) perform as best as they can, (2) simulate brain injury, (3) simulate brain injury and received additional information about the sequelae of head trauma, (4) simulate brain injury and received additional information on how to avoid detection. Furthermore, a group of patients with mild to severe closed head injury performed the tests with best effort. The naïve simulator and the symptom coached groups were the easiest to detect, whereas the symptom plus test coached group was the hardest to detect. The AVLT and the FIT were not suited to detect simulators (sensitivities from 0% to 50.8% at 75% specificity) whereas the STM-BSV detected simulators with 67% - 88% sensitivity at a specificity of 73%. However, the STM-BSV was not robust to coaching. The present investigation shows that symptom validity testing as implemented in the BSV-STM is one clinically useful element in the detection of memory malingering. However, clinicians have to be aware that coaching influences performance in the test.

Medicalising normality? Using a simulated dataset to assess the performance of different diagnostic criteria of HIV-associated cognitive impairment

PubMed Central

De Francesco, Davide; Leech, Robert; Sabin, Caroline A.; Winston, Alan

2018-01-01

Objective The reported prevalence of cognitive impairment remains similar to that reported in the pre-antiretroviral therapy era. This may be partially artefactual due to the methods used to diagnose impairment. In this study, we evaluated the diagnostic performance of the HIV-associated neurocognitive disorder (Frascati criteria) and global deficit score (GDS) methods in comparison to a new, multivariate method of diagnosis. Methods Using a simulated ‘normative’ dataset informed by real-world cognitive data from the observational Pharmacokinetic and Clinical Observations in PeoPle Over fiftY (POPPY) cohort study, we evaluated the apparent prevalence of cognitive impairment using the Frascati and GDS definitions, as well as a novel multivariate method based on the Mahalanobis distance. We then quantified the diagnostic properties (including positive and negative predictive values and accuracy) of each method, using bootstrapping with 10,000 replicates, with a separate ‘test’ dataset to which a pre-defined proportion of ‘impaired’ individuals had been added. Results The simulated normative dataset demonstrated that up to ~26% of a normative control population would be diagnosed with cognitive impairment with the Frascati criteria and ~20% with the GDS. In contrast, the multivariate Mahalanobis distance method identified impairment in ~5%. Using the test dataset, diagnostic accuracy [95% confidence intervals] and positive predictive value (PPV) was best for the multivariate method vs. Frascati and GDS (accuracy: 92.8% [90.3–95.2%] vs. 76.1% [72.1–80.0%] and 80.6% [76.6–84.5%] respectively; PPV: 61.2% [48.3–72.2%] vs. 29.4% [22.2–36.8%] and 33.9% [25.6–42.3%] respectively). Increasing the a priori false positive rate for the multivariate Mahalanobis distance method from 5% to 15% resulted in an increase in sensitivity from 77.4% (64.5–89.4%) to 92.2% (83.3–100%) at a cost of specificity from 94.5% (92.8–95.2%) to 85.0% (81.2–88.5%). Conclusion Our simulations suggest that the commonly used diagnostic criteria of HIV-associated cognitive impairment label a significant proportion of a normative reference population as cognitively impaired, which will likely lead to a substantial over-estimate of the true proportion in a study population, due to their lower than expected specificity. These findings have important implications for clinical research regarding cognitive health in people living with HIV. More accurate methods of diagnosis should be implemented, with multivariate techniques offering a promising solution. PMID:29641619

The sensitivity of laboratory tests assessing driving related skills to dose-related impairment of alcohol: A literature review.

PubMed

Jongen, S; Vuurman, E F P M; Ramaekers, J G; Vermeeren, A

2016-04-01

Laboratory tests assessing driving related skills can be useful as initial screening tools to assess potential drug induced impairment as part of a standardized behavioural assessment. Unfortunately, consensus about which laboratory tests should be included to reliably assess drug induced impairment has not yet been reached. The aim of the present review was to evaluate the sensitivity of laboratory tests to the dose dependent effects of alcohol, as a benchmark, on performance parameters. In total, 179 experimental studies were included. Results show that a cued go/no-go task and a divided attention test with primary tracking and secondary visual search were consistently sensitive to the impairing effects at medium and high blood alcohol concentrations. Driving performance assessed in a simulator was less sensitive to the effects of alcohol as compared to naturalistic, on-the-road driving. In conclusion, replicating results of several potentially useful tests and their predictive validity of actual driving impairment should deserve further research. In addition, driving simulators should be validated and compared head to head to naturalistic driving in order to increase construct validity. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Space agriculture: the effect of micro- and hypo-gravity on soil hydraulics and biogeochemistry in a bioregenerative soil-based cropping unit

NASA Astrophysics Data System (ADS)

Maggi, F.; Pallud, C. E.

2010-12-01

Abstract Increasing interest has developed towards growing plants in soil-based cropping modules as a long-term bioregenerative life support system in space and planetary explorations. Contrary to hydroponics, zeoponics and aeroponics, soil-based cropping would offer an effective approach to sustain food and oxygen production, decompose organic wastes, sequester carbon dioxide, and filter water for the crew. The hydraulic and biogeochemical functioning are highly complex in soil-based systems but such systems provide a self-sustainable microcosm that potentially offers compactness, low energy demand, near-ambient reactor temperatures and pressure, reliability, forgiveness of operational errors or neglect, and a rich biodiversity of microorganisms, all features which are fundamental for the sustainability and reliability of long-term manned space missions. However, the hydraulics and biogeochemical functioning of soil systems exposed to gravities lower than the Earth’s are still unknown. Since gravity is crucial in driving water flow, hypogravity will affect nutrient and oxygen transport in the liquid and gaseous phases, and could lead to suffocation of microorganisms and roots, and emissions of toxic gases. A highly mechanistic model coupling soil hydraulics and nutrient biogeochemistry previously tested on soils on Earth (g = 9.806 m s-2) is used to highlight the effects of gravity on the functioning of cropping units on Mars (0.38g), the Moon (0.16g), and in the international space station (ISS, nearly 0g). For each scenario, we have compared the net leaching of water, the leaching of NH3, NH4+, NO2- and NO3- solutes, the emissions of NH3, CO2, N2O, NO and N2 gases, the concentrations profiles of O2, CO2 and dissolved organic carbon (DOC) in soil, the pH, and the dynamics of various microbial functional groups within the root zone against the same control variables in the soil under terrestrial gravity. The tested hypo- and micro-gravity resulted in 90-100% lower water leaching rates than the Earth’s, 95-100% lower nutrient leaching rates, and lower emissions of NH3 and NO gases (80-95% and 30-40%, respectively). Lower N loss through leaching resulted in 60-100% higher concentration of microbial biomass, but did not alter the vertical stratification of the microorganisms with respect to the stratification on Earth. However, the higher biomass concentration produced higher emissions of N2O (80%), N2 (200%), and CO2 gases (40%), respectively.

Mechanisms of Memory Dysfunction during High Altitude Hypoxia Training in Military Aircrew.

PubMed

Nation, Daniel A; Bondi, Mark W; Gayles, Ellis; Delis, Dean C

2017-01-01

Cognitive dysfunction from high altitude exposure is a major cause of civilian and military air disasters. Pilot training improves recognition of the early symptoms of altitude exposure so that countermeasures may be taken before loss of consciousness. Little is known regarding the nature of cognitive impairments manifesting within this critical window when life-saving measures may still be taken. Prior studies evaluating cognition during high altitude simulation have predominantly focused on measures of reaction time and other basic attention or motor processes. Memory encoding, retention, and retrieval represent critical cognitive functions that may be vulnerable to acute hypoxic/ischemic events and could play a major role in survival of air emergencies, yet these processes have not been studied in the context of high altitude simulation training. In a series of experiments, military aircrew underwent neuropsychological testing before, during, and after brief (15 min) exposure to high altitude simulation (20,000 ft) in a pressure-controlled chamber. Acute exposure to high altitude simulation caused rapid impairment in learning and memory with relative preservation of basic visual and auditory attention. Memory dysfunction was predominantly characterized by deficiencies in memory encoding, as memory for information learned during high altitude exposure did not improve after washout at sea level. Retrieval and retention of memories learned shortly before altitude exposure were also impaired, suggesting further impairment in memory retention. Deficits in memory encoding and retention are rapidly induced upon exposure to high altitude, an effect that could impact life-saving situational awareness and response. (JINS, 2017, 23, 1-10).

Greater involvement of action simulation mechanisms in emotional vs cognitive empathy

PubMed Central

Oliver, Lindsay D; Vieira, Joana B; Neufeld, Richard W J; Dziobek, Isabel; Mitchell, Derek G V

2018-01-01

Abstract Empathy is crucial for successful interpersonal interactions, and it is impaired in many psychiatric and neurological disorders. Action-perception matching, or action simulation mechanisms, has been suggested to facilitate empathy by supporting the simulation of perceived experience in others. However, this remains unclear, and the involvement of the action simulation circuit in cognitive empathy (the ability to adopt another’s perspective) vs emotional empathy (the capacity to share and react affectively to another’s emotional experience) has not been quantitatively compared. Presently, healthy adults completed a classic cognitive empathy task (false belief), an emotional empathy task and an action simulation button-pressing task during functional magnetic resonance imaging. Conjunction analyses revealed common recruitment of the inferior frontal gyrus (IFG), thought to be critical for action-perception matching, during both action simulation and emotional, but not cognitive, empathy. Furthermore, activation was significantly greater in action simulation regions in the left IFG during emotional vs cognitive empathy, and activity in this region was positively correlated with mean feeling ratings during the emotional empathy task. These findings provide evidence for greater involvement of action simulation mechanisms in emotional than cognitive empathy. Thus, the action simulation circuit may be an important target for delineating the pathophysiology of disorders featuring emotional empathy impairments. PMID:29462481

The effect of marihuana dosage on driver performance

DOT National Transportation Integrated Search

1973-10-01

Performance in a complex driving simulator under 4 marihuan dose levels was examined. Car control and tracking appeared to be uninfluenced, but significant dose-related impairment was found on a visual recognition task simulating the search-and-recog...

Land Mobile Satellite Service (LMSS) channel simulator: An end-to-end hardware simulation and study of the LMSS communications links

NASA Technical Reports Server (NTRS)

Salmasi, A. B. (Editor); Springett, J. C.; Sumida, J. T.; Richter, P. H.

1984-01-01

The design and implementation of the Land Mobile Satellite Service (LMSS) channel simulator as a facility for an end to end hardware simulation of the LMSS communications links, primarily with the mobile terminal is described. A number of studies are reported which show the applications of the channel simulator as a facility for validation and assessment of the LMSS design requirements and capabilities by performing quantitative measurements and qualitative audio evaluations for various link design parameters and channel impairments under simulated LMSS operating conditions. As a first application, the LMSS channel simulator was used in the evaluation of a system based on the voice processing and modulation (e.g., NBFM with 30 kHz of channel spacing and a 2 kHz rms frequency deviation for average talkers) selected for the Bell System's Advanced Mobile Phone Service (AMPS). The various details of the hardware design, qualitative audio evaluation techniques, signal to channel impairment measurement techniques, the justifications for criteria of different parameter selection in regards to the voice processing and modulation methods, and the results of a number of parametric studies are further described.

A Multi-Compartment 3-D Finite Element Model of Rectocele and Its Interaction with Cystocele

PubMed Central

Luo, Jiajia; Chen, Luyun; Fenner, Dee E.; Ashton-Miller, James A.; DeLancey, John O. L.

2015-01-01

We developed a subject-specific 3-D finite element model to understand the mechanics underlying formation of female pelvic organ prolapse, specifically a rectocele and its interaction with a cystocele. The model was created from MRI 3-D geometry of a healthy 45 year-old multiparous woman. It included anterior and posterior vaginal walls, levator ani muscle, cardinal and uterosacral ligaments, anterior and posterior arcus tendineus fascia pelvis, arcus tendineus levator ani, perineal body, perineal membrane and anal sphincter. Material properties were mostly from the literature. Tissue impairment was modeled as decreased tissue stiffness based on previous clinical studies. Model equations were solved using Abaqus v 6.11. The sensitivity of anterior and posterior vaginal wall geometry was calculated for different combinations tissue impairments under increasing intraabdominal pressure. Prolapse size was reported as POP-Q point at point Bp for rectocele and point Ba for cystocele. Results show that a rectocele resulted from impairments of the levator ani and posterior compartment support. For 20% levator and 85% posterior support impairments, simulated rectocele size (at POP-Q point: Bp) increased 0.29 mm/cm H2O without apical impairment and 0.36 mm/cm H2O with 60% apical impairment, as intraabdominal pressures increased from 0 to 150 cm H2O. Apical support impairment could result in the development of either a cystocele or rectocele. Simulated repair of posterior compartment support decreased rectocele but increased a preexisting cystocele. We conclude that development of rectocele and cystocele depend on the presence of anterior, posterior, levator and/or or apical support impairments, as well as the interaction of the prolapse with the opposing compartment. PMID:25757664

Teaching Direct Practice Techniques for Work with Elders with Alzheimer's Disease: A Simulated Group Experience.

ERIC Educational Resources Information Center

Kane, Michael N.

2003-01-01

A role-play exercise about Alzheimer's disease was designed to teach group work with memory-impaired elders. Written comments from 26 social work students revealed four outcomes: demystifying practical knowledge, respect for diversity among memory-impaired individuals, increased awareness of elders' internal states, and awareness of the challenges…

Applying Modeling and Simulation to Predict Human Injury due to a Blast Attack on a Shipboard Environment

DTIC Science & Technology

2012-10-01

score is also used to assess inca - pacitation using the Military Functional Incapacity Score (MFIS), which characterizes the degree of impairment in...firefighting), are com- pared to any injury impairments (Champion & Lawnick, 2012). Thus, an individual with a sprained ankle will be inca - pacitated if his

Drinking and driving behavior at stop signs and red lights.

PubMed

Wan, Jingyan; Wu, Changxu; Zhang, Yiqi; Houston, Rebecca J; Chen, Chang Wen; Chanawangsa, Panya

2017-07-01

Alcohol is one of the principal risk factors for motor vehicle crashes. One factor that contributes to vehicle crashes is noncompliance with stop signs and red lights. The present experiment investigated the effects of alcohol and drinking patterns on driving behavior at stop signs and red lights. 28 participants participated in drinking and simulated driving sessions during which they received a moderate dose of alcohol (0.08% BAC) or a placebo. Simulated driving tasks measured participants' driving performance at stop signs and red lights in response to each dose. Results suggested that alcohol impaired the driver control of speed and direction and prolonged their simple and complex reaction time, which were exhibited by impaired speed and lateral control, longer reaction time when the lights turned yellow, and lower deceleration towards stop signs and red lights. Visual degradation may also occur under alcohol intake. It was also suggested that alcohol impaired non-binge drinkers more severely. To be specific, higher acceleration was observed in impaired non-binge drinkers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optical transmission testing based on asynchronous sampling techniques: images analysis containing chromatic dispersion using convolutional neural network

NASA Astrophysics Data System (ADS)

Mrozek, T.; Perlicki, K.; Tajmajer, T.; Wasilewski, P.

2017-08-01

The article presents an image analysis method, obtained from an asynchronous delay tap sampling (ADTS) technique, which is used for simultaneous monitoring of various impairments occurring in the physical layer of the optical network. The ADTS method enables the visualization of the optical signal in the form of characteristics (so called phase portraits) that change their shape under the influence of impairments such as chromatic dispersion, polarization mode dispersion and ASE noise. Using this method, a simulation model was built with OptSim 4.0. After the simulation study, data were obtained in the form of images that were further analyzed using the convolutional neural network algorithm. The main goal of the study was to train a convolutional neural network to recognize the selected impairment (distortion); then to test its accuracy and estimate the impairment for the selected set of test images. The input data consisted of processed binary images in the form of two-dimensional matrices, with the position of the pixel. This article focuses only on the analysis of images containing chromatic dispersion.

Prospective memory impairments in heavy social drinkers are partially overcome by future event simulation.

PubMed

Platt, Bradley; Kamboj, Sunjeev K; Italiano, Tommaso; Rendell, Peter G; Curran, H Valerie

2016-02-01

Recent research suggests that alcohol acutely impairs prospective memory (PM), and this impairment can be overcome using a strategy called 'future event simulation' (FES). Impairment in event-based PM found in detoxifying alcohol-dependent participants is reversed through FES. However, the impact of the most common problematic drinking patterns that do not involve alcohol dependence on PM remains unclear. Here, we examine the impact of frequent heavy drinking on PM and the degree to which any impairments can be reversed through FES. PM was assessed in 19 heavy drinkers (AUDIT scores ≥ 15) and 18 matched control participants (AUDIT scores ≤ 7) using the 'Virtual Week' task both at baseline and again following FES. Heavy drinkers performed significantly worse than controls on regular and irregular time-based PM tasks. FES improved the performance of controls but not of heavy drinkers on time-based tasks. In contrast, FES improved heavy drinkers' performance on event-based PM tasks. These findings suggest that heavy drinkers experience deficits in strategic monitoring processing associated with time-based PM tasks which do not abate after FES. That the same strategy improves their event-based PM suggests that FES may be helpful for individuals with problematic drinking patterns in improving their prospective memory.

The sensitivity of hearing-impaired adults to acoustic attributes in simulated rooms

PubMed Central

Whitmer, William M.; McShefferty, David; Akeroyd, Michael A.

2016-01-01

In previous studies we have shown that older hearing-impaired individuals are relatively insensitive to changes in the apparent width of broadband noises when those width changes were based on differences in interaural coherence [W. Whitmer, B. Seeber and M. Akeroyd, J. Acoust. Soc. Am. 132, 369-379 (2012)]. This insensitivity has been linked to senescent difficulties in resolving binaural fine-structure differences. It is therefore possible that interaural coherence, despite its widespread use, may not be the best acoustic surrogate of spatial perception for the aged and impaired. To test this, we simulated the room impulse responses for various acoustic scenarios with differing coherence and lateral (energy) fraction attributes using room modelling software (ODEON). Bilaterally impaired adult participants were asked to sketch the perceived size of speech tokens and musical excerpts that were convolved with these impulse responses and presented to them in a sound-dampened enclosure through a 24-loudspeaker array. Participants’ binaural acuity was also measured using an interaural phase discrimination task. Corroborating our previous findings, the results showed less sensitivity to interaural coherence in the auditory source width judgments of older hearing-impaired individuals, indicating that alternate acoustic measurements in the design of spaces for the elderly may be necessary. PMID:27213028

The sensitivity of hearing-impaired adults to acoustic attributes in simulated rooms.

PubMed

Whitmer, William M; McShefferty, David; Akeroyd, Michael A

2013-06-02

In previous studies we have shown that older hearing-impaired individuals are relatively insensitive to changes in the apparent width of broadband noises when those width changes were based on differences in interaural coherence [W. Whitmer, B. Seeber and M. Akeroyd, J. Acoust. Soc. Am. 132, 369-379 (2012)]. This insensitivity has been linked to senescent difficulties in resolving binaural fine-structure differences. It is therefore possible that interaural coherence, despite its widespread use, may not be the best acoustic surrogate of spatial perception for the aged and impaired. To test this, we simulated the room impulse responses for various acoustic scenarios with differing coherence and lateral (energy) fraction attributes using room modelling software (ODEON). Bilaterally impaired adult participants were asked to sketch the perceived size of speech tokens and musical excerpts that were convolved with these impulse responses and presented to them in a sound-dampened enclosure through a 24-loudspeaker array. Participants' binaural acuity was also measured using an interaural phase discrimination task. Corroborating our previous findings, the results showed less sensitivity to interaural coherence in the auditory source width judgments of older hearing-impaired individuals, indicating that alternate acoustic measurements in the design of spaces for the elderly may be necessary.

Low levels of alcohol impair driving simulator performance and reduce perception of crash risk in partially sleep deprived subjects.

PubMed

Banks, Siobhan; Catcheside, Peter; Lack, Leon; Grunstein, Ron R; McEvoy, R Doug

2004-09-15

Partial sleep deprivation and alcohol consumption are a common combination, particularly among young drivers. We hypothesized that while low blood alcohol concentration (<0.05 g/dL) may not significantly increase crash risk, the combination of partial sleep deprivation and low blood alcohol concentration would cause significant performance impairment. Experimental Sleep Disorders Unit Laboratory 20 healthy volunteers (mean age 22.8 years; 9 men). Subjects underwent driving simulator testing at 1 am on 2 nights a week apart. On the night preceding simulator testing, subjects were partially sleep deprived (5 hours in bed). Alcohol consumption (2-3 standard alcohol drinks over 2 hours) was randomized to 1 of the 2 test nights, and blood alcohol concentrations were estimated using a calibrated Breathalyzer. During the driving task subjects were monitored continuously with electroencephalography for sleep episodes and were prompted every 4.5 minutes for answers to 2 perception scales-performance and crash risk. Mean blood alcohol concentration on the alcohol night was 0.035 +/- 0.015 g/dL. Compared with conditions during partial sleep deprivation alone, subjects had more microsleeps, impaired driving simulator performance, and poorer ability to predict crash risk in the combined partial sleep deprivation and alcohol condition. Women predicted crash risk more accurately than did men in the partial sleep deprivation condition, but neither men nor women predicted the risk accurately in the sleep deprivation plus alcohol condition. Alcohol at legal blood alcohol concentrations appears to increase sleepiness and impair performance and the detection of crash risk following partial sleep deprivation. When partially sleep deprived, women appear to be either more perceptive of increased crash risk or more willing to admit to their driving limitations than are men. Alcohol eliminated this behavioral difference.

Subjective and neurovegetative changes in healthy volunteers and panic patients performing simulated public speaking.

PubMed

Parente, Alexandre C B V; Garcia-Leal, Cybele; Del-Ben, Cristina M; Guimarães, Francisco S; Graeff, Frederico G

2005-12-01

Drug-free symptomatic panic patients, drug-treated nonsymptomatic patients and healthy controls were submitted to simulated public speaking. Subjective anxiety, cognitive impairment and discomfort measured by the visual analog mood scale as well as skin conductance level were higher in symptomatic patients than in controls at the beginning of the experimental session, nonsymptomatic patients lying in between. Subjective sedation, spontaneous fluctuations of skin conductance, heart rate and blood pressure were similar in the three groups. Preparation and performance of speech decreased sedation while increasing anxiety, cognitive impairment, level and fluctuations of skin conductance, heart rate and blood pressure. Anxiety, cognitive impairment and conductance level were less increased in symptomatic patients than in controls. Electrodermal activity, but not cardiovascular measures of sympathetic arousal correlated with anticipatory anxiety. Chronic treatment with serotonin uptake inhibitors attenuated the differences between panic patients and controls, supporting the participation of serotonin in panic disorder.

Cognitive evaluation by tasks in a virtual reality environment in multiple sclerosis.

PubMed

Lamargue-Hamel, Delphine; Deloire, Mathilde; Saubusse, Aurore; Ruet, Aurélie; Taillard, Jacques; Philip, Pierre; Brochet, Bruno

2015-12-15

The assessment of cognitive impairment in multiple sclerosis (MS) requires large neuropsychological batteries that assess numerous domains. The relevance of these assessments to daily cognitive functioning is not well established. Cognitive ecological evaluation has not been frequently studied in MS. The aim of this study was to determine the interest of cognitive evaluation in a virtual reality environment in a sample of persons with MS with cognitive deficits. Thirty persons with MS with at least moderate cognitive impairment were assessed with two ecological evaluations, an in-house developed task in a virtual reality environment (Urban DailyCog®) and a divided attention task in a driving simulator. Classical neuropsychological testing was also used. Fifty-two percent of the persons with MS failed the driving simulator task and 80% failed the Urban DailyCog®. Virtual reality assessments are promising in identifying cognitive impairment in MS. Copyright © 2015 Elsevier B.V. All rights reserved.

Detrimental Effects of Earphone Conversation on Auditory Environmental Monitoring of Visually Impaired People

ERIC Educational Resources Information Center

Verstijnen, I. M.; van Mierlo, C. M.; de Ruijter, P.

2008-01-01

In order to investigate the effect of concurrent phoning and auditory environmental monitoring, the performance of visually impaired people was observed on a dual task that consisted of two simulation tasks. Subjects wore either a bone conducting headset, or closed or open (air conduction) earphones. Reaction times and the correctness of responses…

The Efficacy of Haptic Simulations to Teach Students with Visual Impairments about Temperature and Pressure

ERIC Educational Resources Information Center

Jones, M. Gail; Childers, Gina; Emig, Brandon; Chevrier, Joël; Tan, Hong; Stevens, Vanessa; List, Jonathan

2014-01-01

Traditional science instruction is typically reliant on visual modes of learning, such as textbooks and graphs. Furthermore, since science instruction is often heavily dependent upon visual cues, students with visual impairment often do not have access to the same educational opportunities in most science classes (Jones, Minogue, Oppewal, Cook,…

Imbalanced pattern completion vs. separation in cognitive disease: network simulations of synaptic pathologies predict a personalized therapeutics strategy.

PubMed

Hanson, Jesse E; Madison, Daniel V

2010-08-13

Diverse Mouse genetic models of neurodevelopmental, neuropsychiatric, and neurodegenerative causes of impaired cognition exhibit at least four convergent points of synaptic malfunction: 1) Strength of long-term potentiation (LTP), 2) Strength of long-term depression (LTD), 3) Relative inhibition levels (Inhibition), and 4) Excitatory connectivity levels (Connectivity). To test the hypothesis that pathological increases or decreases in these synaptic properties could underlie imbalances at the level of basic neural network function, we explored each type of malfunction in a simulation of autoassociative memory. These network simulations revealed that one impact of impairments or excesses in each of these synaptic properties is to shift the trade-off between pattern separation and pattern completion performance during memory storage and recall. Each type of synaptic pathology either pushed the network balance towards intolerable error in pattern separation or intolerable error in pattern completion. Imbalances caused by pathological impairments or excesses in LTP, LTD, inhibition, or connectivity, could all be exacerbated, or rescued, by the simultaneous modulation of any of the other three synaptic properties. Because appropriate modulation of any of the synaptic properties could help re-balance network function, regardless of the origins of the imbalance, we propose a new strategy of personalized cognitive therapeutics guided by assay of pattern completion vs. pattern separation function. Simulated examples and testable predictions of this theorized approach to cognitive therapeutics are presented.

Diagnostic accuracy of evoked potentials for functional impairment after contusive spinal cord injury in adult rats.

PubMed

Thirumala, Parthasarathy; Zhou, James; Krishnan, Rohan; Manem, Nihita; Umredkar, Shreya; Hamilton, D K; Balzer, Jeffrey R; Oudega, Martin

2016-03-01

Iatrogenic spinal cord injury (SCI) is a cause of potentially debilitating post-operative neurologic complications. Currently, intra-operative neurophysiological monitoring (IONM) via somatosensory evoked potentials and motor-evoked potentials is used to detect and prevent impending SCI. However, no empirically validated interventions exist to halt the progression of iatrogenic SCI once it is detected. This is in part due to the lack of a suitable translational model that mimics the circumstances surrounding iatrogenic SCI detected via IONM. Here, we evaluate a model of simulated contusive iatrogenic SCI detected via IONM in adult female Sprague-Dawley rats. We show that transient losses of somatosensory evoked potentials responses are 88.24% sensitive (95% confidence interval [CI] 63.53-98.20) and 80% specific (95% CI 51.91-95.43) for significant functional impairment following simulated iatrogenic SCI. Similarly, we show that transient losses in motor-evoked potentials responses are 70.83% sensitive (95% CI 48.91-87.33) and 100% specific (95% CI 62.91-100.00) for significant functional impairment following simulated iatrogenic SCI. These results indicate that our model is a suitable replica of the circumstances surrounding clinical iatrogenic SCI. Copyright © 2015 Elsevier Ltd. All rights reserved.

Impaired Comprehension of Speed Verbs in Parkinson's Disease.

PubMed

Speed, Laura J; van Dam, Wessel O; Hirath, Priyantha; Vigliocco, Gabriella; Desai, Rutvik H

2017-05-01

A wealth of studies provide evidence for action simulation during language comprehension. Recent research suggests such action simulations might be sensitive to fine-grained information, such as speed. Here, we present a crucial test for action simulation of speed in language by assessing speed comprehension in patients with Parkinson's disease (PD). Based on the patients' motor deficits, we hypothesized that the speed of motion described in language would modulate their performance in semantic tasks. Specifically, they would have more difficulty processing language about relatively fast speed than language about slow speed. We conducted a semantic similarity judgment task on fast and slow action verbs in patients with PD and age-matched healthy controls. Participants had to decide which of two verbs most closely matched a target word. Compared to controls, PD patients were slower making judgments about fast action verbs, but not for judgments about slow action verbs, suggesting impairment in processing language about fast action. Moreover, this impairment was specific to verbs describing fast action performed with the hand. Problems moving quickly lead to difficulties comprehending language about moving quickly. This study provides evidence that speed is an important part of action representations. (JINS, 2017, 23, 412-420).

Alcohol, Drugs and Driving: Implications for Evaluating Driver Impairment

PubMed Central

Brown, Timothy; Milavetz, Gary; Murry, Daryl J.

2013-01-01

Impaired driving is a significant traffic safety problem, and alcohol and drugs taken before driving contribute substantially to this problem. With the increase in use of prescription medication and the decriminalization of some drugs, it has become increasingly important to understand the manifestation of driver impairment. Building upon previous alcohol research conducted at the National Advanced Driving Simulator (NADS), this study enrolled commercial bus drivers to evaluate the effect of triazolam on driving performance to assess difference between placebo, 0.125, and 0.25 mg doses in a randomized and double-blind design. On each of three randomized visits, subjects drove a simulator scenario that had previously been used to demonstrate effects of alcohol on driving performance. Plasma triazolam levels were obtained before the simulator drive. The protocol included participants receiving study medication and placebo over a 3-week period of time one to two weeks apart. The simulator drives used for this analysis occurred approximately 140 minutes after dosing—after the subjects had completed four bus simulator drives and neuropsychological tests over a 2-hour period of time surrounding dosing. The driving scenario contained representative situations on three types of roadways (urban, freeway, and rural) under nighttime driving conditions. Lane keeping performance (ability to drive straight in the lane) under the three doses of triazolam demonstrates that at the 0.25 mg dose, statistically significant effects on performance are observed, but no effects are found at the 0.125 mg level when testing at this time period after dosing. This differs from the effects of alcohol, which shows impairing effects at a 0.05% blood alcohol concentration (BAC) and a greater effect at 0.10% BAC. These results demonstrate the importance of understanding how different types of drugs affect driving performance in realistic driving environments. Although some compounds may have an effect that correlates linearly to dosage, that is not always the case. An understanding of these differences and how they vary across driving tasks is essential to developing a robust evaluation protocol that can accurately describe the effects of a wide variety of drugs on driver impairment. This information can be used to reduce the risk of deleterious effects of therapeutic medications while ensuring their safe and beneficial use. PMID:24406943

Alcohol impairment of performance on steering and discrete tasks in a driving simulator

DOT National Transportation Integrated Search

1974-12-01

In this program a simplified laboratory simulator was developed to test two types of tasks used in driving on the open road: a continuous "steering task" to regulate against gust induced disturbances and an intermittent "discrete response task" requi...

Improving the Effectiveness and Acquisition Management of Selected Weapon Systems: A Summary of Major Issues and Recommended Actions.

DTIC Science & Technology

1982-05-14

need for effective training--a situation which will be impaired until the AH-64 combat mission simulator , now under development, becomes available in...antisubmarine warfare system includes the capability to detect, classify, localize, and destroy the enemy. This capability includes multimillion dollar...to simulate combat situations will simulate only air-to-air activity. Air-to-ground and electronic counter countermeasures simulations were deleted

Impact of sleep deprivation on anaesthesia residents' non-technical skills: a pilot simulation-based prospective randomized trial.

PubMed

Neuschwander, A; Job, A; Younes, A; Mignon, A; Delgoulet, C; Cabon, P; Mantz, J; Tesniere, A

2017-07-01

Sleep deprivation is common in anaesthesia residents, but its impact on performance remains uncertain. Non-technical skills (team working, situation awareness, decision making, and task management) are key components of quality of care in anaesthesia, particularly in crisis situations occurring in the operating room. The impact of sleep deprivation on non-technical skills is unknown. We tested the hypothesis that in anaesthesia residents sleep deprivation is associated with impaired non-technical skills. Twenty anaesthesia residents were randomly allocated to undergo a simulation session after a night shift [sleep-deprived (SLD) group, n =10] or after a night of rest [rested (R) group, n =10] from January to March 2015. The simulated scenario was a situation of crisis management in the operating room. The primary end point was a composite score of anaesthetists' non-technical skills (ANTS) assessed by two blinded evaluators. Non-technical skills were significantly impaired in the SLD group [ANTS score 12.2 (interquartile range 10.5-13)] compared with the R group [14.5 (14-15), P <0.02]. This difference was mainly accounted for by a difference in the team working item. On the day of simulation, the SLD group showed increased sleepiness and decreased confidence in anaesthesia skills. In this randomized pilot trial, sleep deprivation was associated with impaired non-technical skills of anaesthesia residents in a simulated anaesthesia intraoperative crisis scenario. NCT02622217. © The Author 2017. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Comparison of cardiovascular function during the early hours of bed rest and space flight

NASA Technical Reports Server (NTRS)

Lathers, C. M.; Charles, J. B.

1994-01-01

This paper reviews the cardiovascular responses of six healthy male subjects to 6 hours in a 5 degrees head-down bed rest model of weightlessness, and compares these responses to those obtained when subjects were positioned in head-up tilts of 10 degrees, 20 degrees, and 42 degrees, simulating 1/6, 1/3, and 2/3 G, respectively. Thoracic fluid index, cardiac output, stroke volume, and peak flow were measured using impedance cardiography. Cardiac dimensions and volumes were determined from two-dimensional guided M-mode echocardiograms in the left lateral decubitus position at 0, 2, 4, and 6 hours. Cardiovascular response to a stand test were compared before and after bed rest. The impedance values were related to tilt angle for the first 2 hours of tilt; however, after 3 hours, at all four angles, values began to converge, indicating that cardiovascular homeostatic mechanisms seek a common adapted state, regardless of effective gravity level (tilt angle) up to 2/3 G. Echocardiography revealed that left ventricular end-diastolic and end-systolic volume, stroke volume, ejection fraction, heart rate, and cardiac output had returned to control values by hour 6 for all tilt angles. The lack of a significant immediate change in left ventricular end-diastolic volume, despite decrements in stroke volume (P < .05) and heart rate (not significant), indicates that multiple factors may play a role in the adaptation to simulated hypogravity. The echocardiography data indicated that no angle of tilt, whether head-down or head-up for 4 to 6 hours, mimicked exactly the changes in cardiovascular function recorded after 4 to 6 hours of space flight. Changes in left ventricular end-diastolic volume during space flight and tilt may be similar, but follow a different time course. Nevertheless, head-down tilt at 5 degrees for 6 hours mimics some (stroke volume, systolic and diastolic blood pressure, mean arterial blood pressure, and total resistance), but not all, of the changes occurring in an equivalent time of space flight. The magnitude of the change in the mean heart rate response to standing was greater after six hours of tilt at -5 degrees or 10 degrees. Thus, results from the stand test after 6 hours of bed rest at -5 degrees and 10 degrees, but not at 20 degrees or 42 degrees, are similar to those obtained after space flight.

Gravitropic responses of the Avena coleoptile in space and on clinostats. I. Gravitropic response thresholds

NASA Technical Reports Server (NTRS)

Brown, A. H.; Chapman, D. K.; Johnsson, A.; Heathcote, D.

1995-01-01

We conducted a series of gravitropic experiments on Avena coleoptiles in the weightlessness environment of Spacelab. The purpose was to test the threshold stimulus, reciprocity rule and autotropic reactions to a range of g-force stimulations of different intensities and durations The tests avoided the potentially complicating effects of earth's gravity and the interference from clinostat ambiguities. Using slow-speed centrifuges, coleoptiles received transversal accelerations in the hypogravity range between 0.l and 1.0 g over periods that ranged from 2 to 130 min. All responses that occurred in weightlessness were compared to clinostat experiments on earth using the same apparatus. Characteristic gravitropistic response patterns of Atuena were not substantially different from those observed in ground-based experiments. Gravitropic presentation times were extrapolated. The threshold at 1.0 g was less than 1 min (shortest stimulation time 2 min), in agreement with values obtained on the ground. The least stimulus tested, 0.1 g for 130 min, produced a significant response. Therefore the absolute threshold for a gravitropic response is less than 0.1 g.

Human Research Program: 2012 Fiscal Year Annual Report

NASA Technical Reports Server (NTRS)

Effenhauser, Laura

2012-01-01

Crew health and performance are critical to successful human exploration beyond low Earth orbit. Risks to health and performance include physiologic effects from radiation, hypogravity, and planetary environments, as well as unique challenges in medical treatment, human factors, and support of behavioral health. The scientists and engineers of the Human Research Program (HRP) investigate and reduce the greatest risks to human health and performance, and provide essential countermeasures and technologies for human space exploration. In its seventh year of operation, the HRP continued to refine its management architecture of evidence, risks, gaps, tasks, and deliverables. Experiments continued on the International Space Station (ISS), on the ground in analog environments that have features similar to those of spaceflight, and in laboratory environments. Data from these experiments furthered the understanding of how the space environment affects the human system. These research results contributed to scientific knowledge and technology developments that address the human health and performance risks. As shown in this report, HRP has made significant progress toward developing medical care and countermeasure systems for space exploration missions which will ultimately reduce risks to crew health and performance.

Bioregenerative Planetary Life Support Systems Test Complex (BIO-Plex): NASA's Next Human-Rated Testing Facility

NASA Technical Reports Server (NTRS)

Tri, Terry O.

1999-01-01

As a key component in its ground test bed capability, NASA's Advanced Life Support Program has been developing a large-scale advanced life support test facility capable of supporting long-duration evaluations of integrated bioregenerative life support systems with human test crews. This facility-targeted for evaluation of hypogravity compatible life support systems to be developed for use on planetary surfaces such as Mars or the Moon-is called the Bioregenerative Planetary Life Support Systems Test Complex (BIO-Plex) and is currently under development at the Johnson Space Center. This test bed is comprised of a set of interconnected chambers with a sealed internal environment which are outfitted with systems capable of supporting test crews of four individuals for periods exceeding one year. The advanced technology systems to be tested will consist of both biological and physicochemical components and will perform all required crew life support functions. This presentation provides a description of the proposed test "missions" to be supported by the BIO-Plex and the planned development strategy for the facility.

Loss of Parafollicular Cells during Gravitational Changes (Microgravity, Hypergravity) and the Secret Effect of Pleiotrophin

PubMed Central

Albi, Elisabetta; Curcio, Francesco; Spelat, Renza; Lazzarini, Andrea; Lazzarini, Remo; Cataldi, Samuela; Loreti, Elisabetta; Ferri, Ivana; Ambesi-Impiombato, Francesco Saverio

2012-01-01

It is generally known that bone loss is one of the most important complications for astronauts who are exposed to long-term microgravity in space. Changes in blood flow, systemic hormones, and locally produced factors were indicated as important elements contributing to the response of osteoblastic cells to loading, but research in this field still has many questions. Here, the possible biological involvement of thyroid C cells is being investigated. The paper is a comparison between a case of a wild type single mouse and a over-expressing pleiotrophin single mouse exposed to hypogravity conditions during the first animal experiment of long stay in International Space Station (91 days) and three similar mice exposed to hypergravity (2Gs) conditions. We provide evidence that both microgravity and hypergravity induce similar loss of C cells with reduction of calcitonin production. Pleiotrophin over-expression result in some protection against negative effects of gravity change. Potential implication of the gravity mechanic forces in the regulation of bone homeostasis via thyroid equilibrium is discussed. PMID:23284618

Effect of hindlimb suspension on cardiovascular responses to sympathomimetics and lower body negative pressure

NASA Technical Reports Server (NTRS)

Overton, J. Michael; Tipton, Charles M.

1990-01-01

To determine whether hindlimb suspension is associated with the development of cardiovascular deconditioning, male rats were studied before and after undergoing one of three treatment conditions for 9 days: (1) cage control (n = 15, CON), (2) horizontal suspension (n = 15, HOZ), and (3) head-down suspension (n = 18, HDS). Testing included lower body negative pressure administered during chloralose-urethan anesthesia and graded doses of sympathomimetic agents (norepinephrine, phenylephrine, and tyramine) administered to conscious unrestrained animals. Both HDS and HOZ were associated with a small decrease in the hypotensive response to lower body negative pressure. The HOZ group, but not the HDS group, exhibited augmented reflex tachycardia. Furthermore, both HDS and HOZ groups manifested reduced pressor responses to phenylephrine after treatment. These reductions were associated with significantly attenuated increases in mesenteric vascular resistance. However, baroreflex control of heart rate was not altered by the treatment conditions. Collectively, these results indicate that 9 days of HDS in rats does not elicit hemodynamic response patterns generally associated with cardiovascular deconditioning induced by hypogravic conditions.

NASA Tech Briefs, Februrary 2013

NASA Technical Reports Server (NTRS)

2013-01-01

Topics covered include: Measurements of Ultra-Stable Oscillator (USO) Allan Deviations in Space; Gaseous Nitrogen Orifice Mass Flow Calculator; Validation of Proposed Metrics for Two-Body Abrasion Scratch Test Analysis Standards; Rover Low Gain Antenna Qualification for Deep Space Thermal Environments; Automated, Ultra-Sterile Solid Sample Handling and Analysis on a Chip; Measuring and Estimating Normalized Contrast in Infrared Flash Thermography; Spectrally and Radiometrically Stable, Wideband, Onboard Calibration Source; High-Reliability Waveguide Vacuum/Pressure Window; Methods of Fabricating Scintillators With Radioisotopes for Beta Battery Applications; Magnetic Shield for Adiabatic Demagnetization Refrigerators (ADR); CMOS-Compatible SOI MESFETS for Radiation-Hardened DC-to-DC Converters; Silicon Heat Pipe Array; Adaptive Phase Delay Generator; High-Temperature, Lightweight, Self-Healing Ceramic Composites for Aircraft Engine Applications; Treatment to Control Adhesion of Silicone-Based Elastomers; High-Temperature Adhesives for Thermally Stable Aero-Assist Technologies; Rockballer Sample Acquisition Tool; Rock Gripper for Sampling, Mobility, Anchoring, and Manipulation; Advanced Magnetic Materials Methods and Numerical Models for Fluidization in Microgravity and Hypogravity; Data Transfer for Multiple Sensor Networks Over a Broad Temperature Range; Using Combustion Synthesis to Reinforce Berms and Other Regolith Structures; Visible-Infrared Hyperspectral Image Projector; Three-Axis Attitude Estimation With a High-Bandwidth Angular Rate Sensor Change_Detection.m; AGATE: Adversarial Game Analysis for Tactical Evaluation; Ionospheric Simulation System for Satellite Observations and Global Assimilative; Modeling Experiments (ISOGAME); An Extensible, User- Modifiable Framework for Planning Activities; Mission Operations Center (MOC) - Precipitation Processing System (PPS) Interface Software System (MPISS); Automated 3D Damaged Cavity Model Builder for Lower Surface Acreage Tile on Orbiter; Mixed Linear/Square-Root Encoded Single-Slope Ramp Provides Low-Noise ADC with High Linearity for Focal Plane Arrays; RUSHMAPS: Real-Time Uploadable Spherical Harmonic Moment Analysis for Particle Spectrometers; Powered Descent Guidance with General Thrust-Pointing Constraints; X-Ray Detection and Processing Models for Spacecraft Navigation and Timing; and Extreme Ionizing-Radiation-Resistant Bacterium

An Evaluation of the Ability of Amputees to Operate Highway Transport Equipment. Final Report.

ERIC Educational Resources Information Center

McFarland, Ross A.; And Others

To document the driving experience of amputees and to test whether amputees differ from non-amputees in the operation of a simulated motor vehicle, related literature was reviewed, a comprehensive study of private motor vehicle operation by amputees was carried out, and 100 persons (20 non-impaired, non-commercial drivers, 20 non-impaired,…

The Process of Auditory Distraction: Disrupted Attention and Impaired Recall in a Simulated Lecture Environment

ERIC Educational Resources Information Center

Zeamer, Charlotte; Fox Tree, Jean E.

2013-01-01

Literature on auditory distraction has generally focused on the effects of particular kinds of sounds on attention to target stimuli. In support of extensive previous findings that have demonstrated the special role of language as an auditory distractor, we found that a concurrent speech stream impaired recall of a short lecture, especially for…

Alcohol effects on simulated driving performance and self-perceptions of impairment in DUI offenders

PubMed Central

Van Dyke, Nicholas; Fillmore, Mark T.

2014-01-01

Drivers with a history of driving under the influence (DUI) of alcohol self-report heightened impulsivity and display reckless driving behaviors as indicated by increased rates of vehicle crashes, moving violations, and traffic tickets. Such poor behavioral self-regulation could also increase sensitivity to the disruptive effects of alcohol on driving performance. The present study examined the degree to which DUI drivers display an increased sensitivity to the acute impairing effects of alcohol on simulated driving performance and overestimate their driving fitness following alcohol consumption. Adult drivers with a history of DUI and a demographically-matched group of drivers with no history of DUI (controls) were tested following a 0.65 g/kg alcohol and a placebo. Results indicated that alcohol impaired several measures of driving performance and there was no difference between DUI offenders and controls in these impairments. However, following alcohol DUI drivers self-reported a greater ability and willingness to drive compared with controls. These findings indicate that drivers with a history of DUI might perceive themselves as more fit to drive after drinking which could play an important role in their decisions to drink and drive. PMID:25347077

Caffeine antagonism of alcohol-induced driving impairment.

PubMed

Liguori, A; Robinson, J H

2001-07-01

The extent to which caffeine antagonizes alcohol-induced impairment of simulated automobile driving at the current lowest legal American limit (0.08% BrAC) was the focus of this study. Fifteen adults swallowed a capsule (0, 200, or 400 mg caffeine) then drank a beverage (0.0 or 0.6 g/kg ethanol) in a within-subject, double-blind, randomized procedure. Forty-five minutes later, participants completed a test battery of subjective effects scales, dynamic posturography, critical flicker fusion (CFF), choice reaction time (CRT), divided attention (Stroop test), and simulated driving. Alcohol alone increased ratings of 'dizzy', 'drug effect', and 'high', slowed CRT and brake latency, and increased body sway. Caffeine alone increased ratings of 'alert' and 'jittery', but did not significantly affect body sway or psychomotor performance. Both caffeine doses comparably counteracted alcohol impairment of brake latency but not CRT or body sway. Brake latency with either alcohol-caffeine combination remained significantly longer than that with placebo. Stroop and CFF performance were unaffected by any drug condition. The results suggest that caffeine may increase alertness and improve reaction time after alcohol use but will not completely counteract alcohol impairment in a driver.

Preserved Tool Knowledge in the Context of Impaired Action Knowledge: Implications for Models of Semantic Memory

PubMed Central

Garcea, Frank E.; Dombovy, Mary; Mahon, Bradford Z.

2013-01-01

A number of studies have observed that the motor system is activated when processing the semantics of manipulable objects. Such phenomena have been taken as evidence that simulation over motor representations is a necessary and intermediary step in the process of conceptual understanding. Cognitive neuropsychological evaluations of patients with impairments for action knowledge permit a direct test of the necessity of motor simulation in conceptual processing. Here, we report the performance of a 47-year-old male individual (Case AA) and six age-matched control participants on a number of tests probing action and object knowledge. Case AA had a large left-hemisphere frontal-parietal lesion and hemiplegia affecting his right arm and leg. Case AA presented with impairments for object-associated action production, and his conceptual knowledge of actions was severely impaired. In contrast, his knowledge of objects such as tools and other manipulable objects was largely preserved. The dissociation between action and object knowledge is difficult to reconcile with strong forms of the embodied cognition hypothesis. We suggest that these, and other similar findings, point to the need to develop tractable hypotheses about the dynamics of information exchange among sensory, motor and conceptual processes. PMID:23641205

Alcohol effects on simulated driving performance and self-perceptions of impairment in DUI offenders.

PubMed

Van Dyke, Nicholas; Fillmore, Mark T

2014-12-01

Drivers with a history of driving under the influence (DUI) of alcohol self-report heightened impulsivity and display reckless driving behaviors as indicated by increased rates of vehicle crashes, moving violations, and traffic tickets. Such poor behavioral self-regulation could also increase sensitivity to the disruptive effects of alcohol on driving performance. The present study examined the degree to which DUI drivers display an increased sensitivity to the acute impairing effects of alcohol on simulated driving performance and overestimate their driving fitness following alcohol consumption. Adult drivers with a history of DUI and a demographically matched group of drivers with no history of DUI (controls) were tested following a 0.65 g/kg alcohol and a placebo. Results indicated that alcohol impaired several measures of driving performance, and there was no difference between DUI offenders and controls in these impairments. However, following alcohol, DUI drivers self-reported a greater ability and willingness to drive compared with controls. These findings indicate that drivers with a history of DUI might perceive themselves as more fit to drive after drinking, which could play an important role in their decisions to drink and drive. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Medications and impaired driving.

PubMed

Hetland, Amanda; Carr, David B

2014-04-01

To describe the association of specific medication classes with driving outcomes and provide clinical recommendations. The MEDLINE and EMBASE databases were searched for articles published from January 1973 to June 2013 on classes of medications associated with driving impairment. The search included outcome terms such as automobile driving, motor vehicle crash, driving simulator, and road tests. Only English-language articles that contained findings from observational or interventional designs with ≥ 10 participants were included in this review. Cross-sectional studies, case series, and case reports were excluded. Driving is an important task and activity for the majority of adults. Some commonly prescribed medications have been associated with driving impairment measured by road performance, driving simulation, and/or motor vehicle crashes. This review of 30 studies identified findings with barbiturates, benzodiazepines, hypnotics, antidepressants, opioid and nonsteroidal analgesics, anticonvulsants, antipsychotics, antiparkinsonian agents, skeletal muscle relaxants, antihistamines, anticholinergic medications, and hypoglycemic agents. Additional studies of medication impact on sedation, sleep latency, and psychomotor function, as well as the role of alcohol, are also discussed. Psychotropic agents and those with central nervous system side effects were associated with measures of impaired driving performance. It is difficult to determine if such associations are actually a result of medication use or the medical diagnosis itself. Regardless, clinicians should be aware of the increased risk of impaired driving with specific classes of medications, educate their patients, and/or consider safer alternatives.

HSPF Toolkit: a New Tool for Stormwater Management at the Watershed Scale

EPA Science Inventory

The Hydrological Simulation Program - FORTRAN (HSPF) is a comprehensive watershed model endorsed by US EPA for simulating point and nonpoint source pollutants. The model is used for developing total maximum daily load (TMDL) plans for impaired water bodies; as such, HSPF is the c...

Reduced Physical Fitness in Patients With Heart Failure as a Possible Risk Factor for Impaired Driving Performance

PubMed Central

Alosco, Michael L.; Penn, Marc S.; Spitznagel, Mary Beth; Cleveland, Mary Jo; Ott, Brian R.

2015-01-01

OBJECTIVE. Reduced physical fitness secondary to heart failure (HF) may contribute to poor driving; reduced physical fitness is a known correlate of cognitive impairment and has been associated with decreased independence in driving. No study has examined the associations among physical fitness, cognition, and driving performance in people with HF. METHOD. Eighteen people with HF completed a physical fitness assessment, a cognitive test battery, and a validated driving simulator scenario. RESULTS. Partial correlations showed that poorer physical fitness was correlated with more collisions and stop signs missed and lower scores on a composite score of attention, executive function, and psychomotor speed. Cognitive dysfunction predicted reduced driving simulation performance. CONCLUSION. Reduced physical fitness in participants with HF was associated with worse simulated driving, possibly because of cognitive dysfunction. Larger studies using on-road testing are needed to confirm our findings and identify clinical interventions to maximize safe driving. PMID:26122681

A Prospective Study of Loss of Consciousness in Epilepsy Using Virtual Reality Driving Simulation and Other Video Games

PubMed Central

Yang, Li; Morland, Thomas B.; Schmits, Kristen; Rawson, Elizabeth; Narasimhan, Poojitha; Motelow, Joshua E.; Purcaro, Michael J.; Peng, Kathy; Raouf, Saned; DeSalvo, Matthew N.; Oh, Taemin; Wilkerson, Jerome; Bod, Jessica; Srinivasan, Aditya; Kurashvili, Pimen; Anaya, Joseph; Manza, Peter; Danielson, Nathan; Ransom, Christopher B.; Huh, Linda; Elrich, Susan; Padin-Rosado, Jose; Naidu, Yamini; Detyniecki, Kamil; Hamid, Hamada; Fattahi, Pooia; Astur, Robert; Xiao, Bo; Duckrow, Robert B.; Blumenfeld, Hal

2010-01-01

Patients with epilepsy are at risk of traffic accidents when they have seizures while driving. However, driving is an essential part of normal daily life in many communities, and depriving patients of driving privileges can have profound consequences for their economic and social well being. In the current study, we collected ictal performance data from a driving simulator and two other video games in patients undergoing continuous video/EEG monitoring. We captured 22 seizures in 13 patients and found that driving impairment during seizures differed both in terms of magnitude and character, depending on the seizure type. Our study documents the feasibility of the prospective study of driving and other behaviors during seizures through the use of computer-based tasks. This methodology may be applied to further describe differential driving impairment in specific types of seizures and to gain data on anatomical networks disrupted in seizures that impair consciousness and driving safety. PMID:20537593

Brain network alterations and vulnerability to simulated neurodegeneration in breast cancer.

PubMed

Kesler, Shelli R; Watson, Christa L; Blayney, Douglas W

2015-08-01

Breast cancer and its treatments are associated with mild cognitive impairment and brain changes that could indicate an altered or accelerated brain aging process. We applied diffusion tensor imaging and graph theory to measure white matter organization and connectivity in 34 breast cancer survivors compared with 36 matched healthy female controls. We also investigated how brain networks (connectomes) in each group responded to simulated neurodegeneration based on network attack analysis. Compared with controls, the breast cancer group demonstrated significantly lower fractional anisotropy, altered small-world connectome properties, lower brain network tolerance to systematic region (node), and connection (edge) attacks and significant cognitive impairment. Lower tolerance to network attack was associated with cognitive impairment in the breast cancer group. These findings provide further evidence of diffuse white matter pathology after breast cancer and extend the literature in this area with unique data demonstrating increased vulnerability of the post-breast cancer brain network to future neurodegenerative processes. Copyright © 2015 Elsevier Inc. All rights reserved.

The impact of meal timing on performance, sleepiness, gastric upset, and hunger during simulated night shift.

PubMed

Grant, Crystal Leigh; Dorrian, Jillian; Coates, Alison Maree; Pajcin, Maja; Kennaway, David John; Wittert, Gary Allen; Heilbronn, Leonie Kaye; Vedova, Chris Della; Gupta, Charlotte Cecilia; Banks, Siobhan

2017-10-07

This study examined the impact of eating during simulated night shift on performance and subjective complaints. Subjects were randomized to eating at night (n=5; 23.2 ± 5.5 y) or not eating at night (n=5; 26.2 ± 6.4 y). All participants were given one sleep opportunity of 8 h (22:00 h-06:00 h) before transitioning to the night shift protocol. During the four days of simulated night shift participants were awake from 16:00 h-10:00 h with a daytime sleep of 6 h (10:00 h-16:00 h). In the simulated night shift protocol, meals were provided at ≈0700 h, 1900 h and 0130 h (eating at night); or ≈0700 h, 0930 h, 1410 h and 1900 h (not eating at night). Subjects completed sleepiness, hunger and gastric complaint scales, a Digit Symbol Substitution Task and a 10-min Psychomotor Vigilance Task. Increased sleepiness and performance impairment was evident in both conditions at 0400 h (p<0.05). Performance impairment at 0400 h was exacerbated when eating at night. Not eating at night was associated with elevated hunger and a small but significant elevation in stomach upset across the night (p<0.026). Eating at night was associated with elevated bloating on night one, which decreased across the protocol. Restricting food intake may limit performance impairments at night. Dietary recommendations to improve night-shift performance must also consider worker comfort.

The impact of meal timing on performance, sleepiness, gastric upset, and hunger during simulated night shift

PubMed Central

GRANT, Crystal Leigh; DORRIAN, Jillian; COATES, Alison Maree; PAJCIN, Maja; KENNAWAY, David John; WITTERT, Gary Allen; HEILBRONN, Leonie Kaye; DELLA VEDOVA, Chris; GUPTA, Charlotte Cecilia; BANKS, Siobhan

2017-01-01

This study examined the impact of eating during simulated night shift on performance and subjective complaints. Subjects were randomized to eating at night (n=5; 23.2 ± 5.5 y) or not eating at night (n=5; 26.2 ± 6.4 y). All participants were given one sleep opportunity of 8 h (22:00 h-06:00 h) before transitioning to the night shift protocol. During the four days of simulated night shift participants were awake from 16:00 h-10:00 h with a daytime sleep of 6 h (10:00 h-16:00 h). In the simulated night shift protocol, meals were provided at ≈0700 h, 1900 h and 0130 h (eating at night); or ≈0700 h, 0930 h, 1410 h and 1900 h (not eating at night). Subjects completed sleepiness, hunger and gastric complaint scales, a Digit Symbol Substitution Task and a 10-min Psychomotor Vigilance Task. Increased sleepiness and performance impairment was evident in both conditions at 0400 h (p<0.05). Performance impairment at 0400 h was exacerbated when eating at night. Not eating at night was associated with elevated hunger and a small but significant elevation in stomach upset across the night (p<0.026). Eating at night was associated with elevated bloating on night one, which decreased across the protocol. Restricting food intake may limit performance impairments at night. Dietary recommendations to improve night-shift performance must also consider worker comfort. PMID:28740034

Exploration of a physiologically-inspired hearing-aid algorithm using a computer model mimicking impaired hearing.

PubMed

Jürgens, Tim; Clark, Nicholas R; Lecluyse, Wendy; Meddis, Ray

2016-01-01

To use a computer model of impaired hearing to explore the effects of a physiologically-inspired hearing-aid algorithm on a range of psychoacoustic measures. A computer model of a hypothetical impaired listener's hearing was constructed by adjusting parameters of a computer model of normal hearing. Absolute thresholds, estimates of compression, and frequency selectivity (summarized to a hearing profile) were assessed using this model with and without pre-processing the stimuli by a hearing-aid algorithm. The influence of different settings of the algorithm on the impaired profile was investigated. To validate the model predictions, the effect of the algorithm on hearing profiles of human impaired listeners was measured. A computer model simulating impaired hearing (total absence of basilar membrane compression) was used, and three hearing-impaired listeners participated. The hearing profiles of the model and the listeners showed substantial changes when the test stimuli were pre-processed by the hearing-aid algorithm. These changes consisted of lower absolute thresholds, steeper temporal masking curves, and sharper psychophysical tuning curves. The hearing-aid algorithm affected the impaired hearing profile of the model to approximate a normal hearing profile. Qualitatively similar results were found with the impaired listeners' hearing profiles.

Losing sight of the future: Impaired semantic prospection following medial temporal lobe lesions

PubMed Central

Race, Elizabeth; Keane, Margaret M.; Verfaellie, Mieke

2012-01-01

The ability to imagine the future (prospection) relies on many of the same brain regions that support memory for the past. To date, scientific research has primarily focused on the neural substrates of episodic forms of prospection (mental simulation of spatiotemporally specific future events) whereas little is known about the neural substrates of semantic prospection (mental simulation of future nonpersonal facts). Of particular interest is the role of the medial temporal lobes, and specifically the hippocampus. While the hippocampus has been proposed to play a key role in episodic prospection, recent evidence suggests that it may not play a similar role in semantic prospection. To examine this possibility, amnesic patients with medial temporal lobe (MTL) lesions were asked to imagine future issues occurring in the public domain. The results showed that patients could list general semantic facts about the future, but when probed to elaborate, patients produced impoverished descriptions that lacked semantic detail. This impairment occurred despite intact performance on standard neuropsychological tests of semantic processing, and did not simply reflect deficits in narrative construction. The performance of a patient with damage limited to the hippocampus was similar to that of the remaining MTL patients and amnesic patients’ impaired elaboration of the semantic future correlated with their impaired elaboration of the semantic past. Together, these results provide novel evidence from MTL amnesia that memory and prospection are linked in the semantic domain and reveal that the medial temporal lobes play a critical role in the construction of detailed, multi-element semantic simulations. PMID:23197413

Automated Classification of Phonological Errors in Aphasic Language

PubMed Central

Ahuja, Sanjeev B.; Reggia, James A.; Berndt, Rita S.

1984-01-01

Using heuristically-guided state space search, a prototype program has been developed to simulate and classify phonemic errors occurring in the speech of neurologically-impaired patients. Simulations are based on an interchangeable rule/operator set of elementary errors which represent a theory of phonemic processing faults. This work introduces and evaluates a novel approach to error simulation and classification, it provides a prototype simulation tool for neurolinguistic research, and it forms the initial phase of a larger research effort involving computer modelling of neurolinguistic processes.

Classification and simulation of stereoscopic artifacts in mobile 3DTV content

NASA Astrophysics Data System (ADS)

Boev, Atanas; Hollosi, Danilo; Gotchev, Atanas; Egiazarian, Karen

2009-02-01

We identify, categorize and simulate artifacts which might occur during delivery stereoscopic video to mobile devices. We consider the stages of 3D video delivery dataflow: content creation, conversion to the desired format (multiview or source-plus-depth), coding/decoding, transmission, and visualization on 3D display. Human 3D vision works by assessing various depth cues - accommodation, binocular depth cues, pictorial cues and motion parallax. As a consequence any artifact which modifies these cues impairs the quality of a 3D scene. The perceptibility of each artifact can be estimated through subjective tests. The material for such tests needs to contain various artifacts with different amounts of impairment. We present a system for simulation of these artifacts. The artifacts are organized in groups with similar origins, and each group is simulated by a block in a simulation channel. The channel introduces the following groups of artifacts: sensor limitations, geometric distortions caused by camera optics, spatial and temporal misalignments between video channels, spatial and temporal artifacts caused by coding, transmission losses, and visualization artifacts. For the case of source-plus-depth representation, artifacts caused by format conversion are added as well.

Crip for a day: The unintended negative consequences of disability simulations.

PubMed

Nario-Redmond, Michelle R; Gospodinov, Dobromir; Cobb, Angela

2017-08-01

To investigate the impact of disability simulations on mood, self-ascribed disability stereotypes, attitudes about interacting with disabled individuals, and behavioral intentions for improving campus accessibility. Experiment 1 evaluated disability-awareness simulations by randomly assigning undergraduates (N = 60) with and without disabilities to stations simulating either dyslexia, hearing or mobility impairments. Experiment 2 extended the field study into the lab where undergraduates (N = 50) with and without disabilities each completed low vision, hearing impairment, and dyslexia simulations. Both studies incorporated pretest-posttest measures of mood, self-ascribed disability stereotypes, and attitudinal measures. In both experiments, disability simulations made participants feel more confused, embarrassed, helpless, and more vulnerable to becoming disabled themselves compared to baseline. Following the simulations, empathetic concern (warmth) toward disabled people increased in both studies, but attitudes about interacting did not improve. In Experiment 1, postsimulation anxiety, embarrassment, and helplessness were highest for those who used wheelchairs or simulated dyslexia. In Experiment 2, participants judged themselves less competent, expressed more pity, expressed more interaction discomfort, and were not more willing to interview disabled students for an accessibility project following the simulations compared to baseline. In addition, Experiment 2 found frustration, guilt, anxiety, and depression were most pronounced among those who interacted with disabled people less than once per month. Simulating disabilities promotes distress and fails to improve attitudes toward disabled people, undermining efforts to improve integration even while participants report more empathetic concern and "understanding of what the disability experience is like." (PsycINFO Database Record (c) 2017 APA, all rights reserved).

More Education May Limit Disability and Extend Life For People With Cognitive Impairment.

PubMed

Laditka, Sarah B; Laditka, James N

2014-08-01

Education is associated with longer life and less disability. Living longer increases risks of cognitive impairment, often producing disability. We examined associations among education, disability, and life expectancy for people with cognitive impairment, following a 1992 cohort ages 55+ for 23 063 person-years (Panel Study of Income Dynamics, n = 2165). We estimated monthly probabilities of disability and death for 7 education levels, adjusting for age, gender, ethnicity, and cognitive status. We used the probabilities to simulate populations with age-specific cognitive impairment incidence and monthly disability status through death. For those with cognitive impairment, education was associated with longer life and less disability. Among them, college-educated white women lived 3.2 more years than those with <8 years education, disabled 24.4% of life from age 55 compared with 36.7% (P< .0001). Increasing education will lengthen lives. Living longer, more people will have cognitive impairment. Education may limit their risk of disability and its duration. © The Author(s) 2014.

Cognitive impairment and driving safety.

PubMed

Eby, David W; Molnar, Lisa J

2012-11-01

As the populations of many countries continue to age, cognitive impairment will likely become more common. Individuals with cognitive impairment pose special challenges for families, health professionals, driving safety professionals, and the larger community, particularly if these older adults depend on driving as their primary means of community mobility. It is vital that we continue to extend our knowledge about the driving behavior of individuals' with cognitive impairment, as well as try to develop effective means of screening and assessing these individuals for fitness to drive and help facilitate their transition to non-driving when appropriate. This special issue is intended to provide researchers and practitioners an opportunity to present the most recent research findings on driving-related issues among older adults with cognitive impairment. The issue contains 11 original contributions from seven countries. The topics covered by these papers are: crash risks; screening, assessment, and fitness to drive; driving performance using a driving simulator; and driving behaviors and driving-related decisions of people with cognitive impairments. Copyright © 2012. Published by Elsevier Ltd.

ALCOHOL AND DISTRACTION INTERACT TO IMPAIR DRIVING PERFORMANCE

PubMed Central

Harrison, Emily L. R.; Fillmore, Mark T.

2011-01-01

Background Recognition of the risks associated with alcohol intoxication and driver distraction has led to a wealth of simulated driving research aimed at studying the adverse effects of each of these factors. Research on driving has moved beyond the individual, separate examination of these factors to the examination of potential interactions between alcohol intoxication and driver distraction. In many driving situations, distractions are commonplace and might have little or no disruptive influence on primary driving functions. Yet, such distractions might become disruptive to a driver who is intoxicated. Methods The present study examined the interactive impairing effects of alcohol intoxication and driver distraction on simulated driving performance in 40 young adult drivers using a divided attention task as a distracter activity. The interactive influence of alcohol and distraction was tested by having drivers perform the driving task under four different conditions: 0.65 g/kg alcohol; 0.65 g/kg alcohol + divided attention; placebo; and placebo + divided attention. Results As hypothesized, divided attention had no impairing effect on driving performance in sober drivers. However, under alcohol, divided attention exacerbated the impairing effects of alcohol on driving precision. Conclusions Alcohol and distraction continue to be appropriate targets for research into ways to reduce the rates of driving-related fatalities and injuries. Greater consideration of how alcohol and distraction interact to impair aspects of driving performance can further efforts to create prevention and intervention measures to protect drivers, particularly young adults. PMID:21277119

Alcohol and distraction interact to impair driving performance.

PubMed

Harrison, Emily L R; Fillmore, Mark T

2011-08-01

Recognition of the risks associated with alcohol intoxication and driver distraction has led to a wealth of simulated driving research aimed at studying the adverse effects of each of these factors. Research on driving has moved beyond the individual, separate examination of these factors to the examination of potential interactions between alcohol intoxication and driver distraction. In many driving situations, distractions are commonplace and might have little or no disruptive influence on primary driving functions. Yet, such distractions might become disruptive to a driver who is intoxicated. The present study examined the interactive impairing effects of alcohol intoxication and driver distraction on simulated driving performance in 40 young adult drivers using a divided attention task as a distracter activity. The interactive influence of alcohol and distraction was tested by having drivers perform the driving task under four different conditions: 0.65 g/kg alcohol; 0.65 g/kg alcohol+divided attention; placebo; and placebo+divided attention. As hypothesized, divided attention had no impairing effect on driving performance in sober drivers. However, under alcohol, divided attention exacerbated the impairing effects of alcohol on driving precision. Alcohol and distraction continue to be appropriate targets for research into ways to reduce the rates of driving-related fatalities and injuries. Greater consideration of how alcohol and distraction interact to impair aspects of driving performance can further efforts to create prevention and intervention measures to protect drivers, particularly young adults. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Evaluation of Aztreonam Dosing Regimens in Patients With Normal and Impaired Renal Function: A Population Pharmacokinetic Modeling and Monte Carlo Simulation Analysis.

PubMed

Xu, Hongmei; Zhou, Wangda; Zhou, Diansong; Li, Jianguo; Al-Huniti, Nidal

2017-03-01

Aztreonam is a monocyclic β-lactam antibiotic often used to treat infections caused by Enterobacteriaceae or Pseudomonas aeruginosa. Despite the long history of clinical use, population pharmacokinetic modeling of aztreonam in renally impaired patients is not yet available. The aims of this study were to assess the impact of renal impairment on aztreonam exposure and to evaluate dosing regimens for patients with renal impairment. A population model describing aztreonam pharmacokinetics following intravenous administration was developed using plasma concentrations from 42 healthy volunteers and renally impaired patients from 2 clinical studies. The final pharmacokinetic model was used to predict aztreonam plasma concentrations and evaluate the probability of pharmacodynamic target attainment (PTA) in patients with different levels of renal function. A 2-compartment model with first-order elimination adequately described aztreonam pharmacokinetics. The population mean estimates of aztreonam clearance, intercompartmental clearance, volume of distribution of the central compartment, and volume of distribution of the peripheral compartment were 4.93 L/h, 9.26 L/h, 7.43 L, and 6.44 L, respectively. Creatinine clearance and body weight were the most significant variables to explain patient variability in aztreonam clearance and volume of distribution, respectively. Simulations using the final pharmacokinetic model resulted in a clinical susceptibility break point of 4 and 8 mg/L, respectively, based on the clinical use of 1- and 2-g loading doses with the same or reduced maintenance dose every 8 hours for various renal deficiency patients. The population pharmacokinetic modeling and PTA estimation support adequate PTAs (>90% PTA) from the aztreonam label for dose adjustment of aztreonam in patients with moderate and severe renal impairment. © 2016, The American College of Clinical Pharmacology.

Effects of dexamphetamine with and without alcohol on simulated driving.

PubMed

Simons, Ries; Martens, Marieke; Ramaekers, Jan; Krul, Arno; Klöpping-Ketelaars, Ineke; Skopp, Gisela

2012-08-01

In party circuits dexamphetamine is frequently used in combination with alcohol. It is hypothesized that co-administration of dexamphetamine to alcohol might reduce the sedative effects of alcohol, but may potentiate risk-taking behaviour. The study was aimed at assessing the effects of alcohol, dexamphetamine and the combination of both on simulated driving and cognitive performance. Eighteen subjects participated in a randomized, crossover, placebo-controlled study employing four conditions: 10 mg dexamphetamine, 0.8 g/kg alcohol, 10 mg dexamphetamine + 0.8 g/kg alcohol, and placebo. Fundamental driving skills and risk-taking behaviour were assessed in a driving simulator. Subjects also completed vigilance and divided attention tasks, and subjective ratings. Mean BAC levels during simulated driving were between 0.91‰ and 0.64‰. Subjects using alcohol showed a significantly larger mean standard deviation of lateral position and shorter accepted gap time and distance. Use of alcohol or dexamphetamine + alcohol was associated with a higher frequency of red light running and collisions than the dexamphetamine or placebo conditions. Performance of vigilance and divided attention tasks was significantly impaired in the alcohol condition and, to a lesser degree, in the dexamphetamine + alcohol condition. Single doses of 0.8 g/kg alcohol increased risk-taking behaviours and impaired tracking, attention and reaction time during a 3-h period after drinking when BACs declined from 0.9 to 0.2 mg/ml. The stimulatory effects of co-administration of dexamphetamine 10 mg were not sufficient to overcome the impairing effects of alcohol on skills related to driving.

Exploring the content and quality of episodic future simulations in semantic dementia.

PubMed

Irish, Muireann; Addis, Donna Rose; Hodges, John R; Piguet, Olivier

2012-12-01

Semantic dementia (SD) is a progressive neurodegenerative disorder characterised by the amodal loss of semantic knowledge in the context of relatively preserved recent episodic memory. Recent studies have demonstrated that despite relatively intact episodic memory the capacity for future simulation in SD is profoundly impaired, resulting in an asymmetric profile where past retrieval is significantly better than future simulation (referred to as a past>future effect). Here, we sought to identify the origins of this asymmetric profile by conducting a fine-grained analysis of the contextual details provided during past retrieval and future simulation in SD. Participants with SD (n=14), Alzheimer's disease (n=11), and healthy controls (n=14) had previously completed an experimental past-future interview in which they generated three past events from the previous year, and three future events in the next year, and provided subjective qualitative ratings of vividness, emotional valence, emotional intensity, task difficulty, and personal significance for each event described. Our results confirmed the striking impairment for future simulation in SD, despite a relative preservation of past episodic retrieval. Examination of the contextual details provided for past memories and future simulations revealed significant impairments irrespective of contextual detail type for future simulations in SD, and demonstrated that the future thinking deficit in this cohort was driven by a marked decline in the provision of internal (episodic) event details. In contrast with this past>future effect for internal event details, SD patients displayed a future>past effect for external (non-episodic) event details. Analyses of the qualitative ratings provided for past and future events indicated that SD patients' phenomenological experience did not differ between temporal conditions. Our findings underscore the fact that successful extraction of episodic elements from the past is not sufficient for the generation of novel future simulations in SD. The notable disconnect between objective task performance and patients' subjective experience during future simulation likely reflects the tendency of SD patients to recast entire past events into the future condition. Accordingly, the familiarity of the recapitulated details results in similar ratings of vividness and emotionality across temporal conditions, despite marked differences in the richness of contextual details as the patient moves from the past to the future. Copyright © 2012 Elsevier Ltd. All rights reserved.

Oculomotor Reflexes as a Test of Visual Dysfunctions in Cognitively Impaired Observers

DTIC Science & Technology

2013-09-01

right. Gaze horizontal position is plotted along the y-axis. The red bar indicates a visual nystagmus event detected by the filter. (d) A mild curse word...experimental conditions were chosen to simulate testing cognitively impaired observers. Reflex Stimulus Functions Visual Nystagmus luminance grating low-level...developed a new stimulus for visual nystagmus to 8 test visual motion processing in the presence of incoherent motion noise. The drifting equiluminant

Directing driver attention with augmented reality cues

PubMed Central

Rusch, Michelle L.; Schall, Mark C.; Gavin, Patrick; Lee, John D.; Dawson, Jeffrey D.; Vecera, Shaun; Rizzo, Matthew

2013-01-01

This simulator study evaluated the effects of augmented reality (AR) cues designed to direct the attention of experienced drivers to roadside hazards. Twenty-seven healthy middle-aged licensed drivers with a range of attention capacity participated in a 54 mile (1.5 hour) drive in an interactive fixed-base driving simulator. Each participant received AR cues to potential roadside hazards in six simulated straight (9 mile long) rural roadway segments. Drivers were evaluated on response time for detecting a potentially hazardous event, detection accuracy for target (hazard) and non-target objects, and headway with respect to the hazards. Results showed no negative outcomes associated with interference. AR cues did not impair perception of non-target objects, including for drivers with lower attentional capacity. Results showed near significant response time benefits for AR cued hazards. AR cueing increased response rate for detecting pedestrians and warning signs but not vehicles. AR system false alarms and misses did not impair driver responses to potential hazards. PMID:24436635

Amblyopic deficits in detecting a dotted line in noise.

PubMed

Mussap, A J; Levi, D M

2000-01-01

We compared detectability of a dotted line masked by random-dot noise for the amblyopic versus non-amblyopic eye of two strabismic amblyopes. Small but consistent deficits in the amblyopic eye of these observers were found, and shown to be limited to dotted-line targets composed of greater than seven dots (with performance being normal for targets of less than seven dots). These deficits were unrelated to impaired visual acuity, impaired sensitivity to dot density, and differential positional uncertainty between the eyes of our observers. The deficits were also unlikely to be due to CSF losses due to abnormal low-spatial-frequency filters involved in detecting long chains of collinear dots. Instead, the results of simulations indicate that the inefficiency in utilising large numbers of dots is due to deficits of global, integrative processes in strabismic amblyopes. These simulations also show that while neither undersampling nor positional uncertainty of inputs into integrative processes can themselves account for the amblyopic deficits, if such abnormal inputs lead to the development of stunted integrative processes then impaired sensitivity to long chains of collinear dots is indeed predicted.

Both texting and eating are associated with impaired simulated driving performance.

PubMed

Alosco, Michael L; Spitznagel, Mary Beth; Fischer, Kimberly Hall; Miller, Lindsay A; Pillai, Vivek; Hughes, Joel; Gunstad, John

2012-09-01

Distracted driving is a known contributor to traffic accidents, and many states have banned texting while driving. However, little is known about the potential accident risk of other common activities while driving, such as eating. The objective of the current study was to examine the adverse impact of eating/drinking behavior relative to texting and nondistracted behaviors on a simulated driving task. A total of 186 participants were recruited from undergraduate psychology courses over 2 semesters at Kent State University. We utilized the Kent Multidimensional Assessment Driving Simulation (K-MADS) to compare simulated driving performance among participants randomly assigned to texting (N = 45), eating (N = 45), and control (N = 96) conditions. Multivariate analyses of variance (MANOVA) were conducted to examine between-group differences on simulated driving indices. MANOVA analyses indicated that groups differed in simulated driving performance, F(14, 366) = 7.70, P < .001. Both texting and eating produced impaired driving performance relative to controls, though these behaviors had approximately equal effect. Specifically, both texting and eating groups had more collisions, pedestrian strikes, and center line crossings than controls. In addition, the texting group had more road edge excursions than either eating or control participants and the eating group missed more stop signs than controls. These findings suggest that both texting and eating are associated with poorer simulated driving performance. Future work is needed to determine whether these findings generalize to real-world driving and the development of strategies to reduce distracted driving.

Image jitter enhances visual performance when spatial resolution is impaired.

PubMed

Watson, Lynne M; Strang, Niall C; Scobie, Fraser; Love, Gordon D; Seidel, Dirk; Manahilov, Velitchko

2012-09-06

Visibility of low-spatial frequency stimuli improves when their contrast is modulated at 5 to 10 Hz compared with stationary stimuli. Therefore, temporal modulations of visual objects could enhance the performance of low vision patients who primarily perceive images of low-spatial frequency content. We investigated the effect of retinal-image jitter on word recognition speed and facial emotion recognition in subjects with central visual impairment. Word recognition speed and accuracy of facial emotion discrimination were measured in volunteers with AMD under stationary and jittering conditions. Computer-driven and optoelectronic approaches were used to induce retinal-image jitter with duration of 100 or 166 ms and amplitude within the range of 0.5 to 2.6° visual angle. Word recognition speed was also measured for participants with simulated (Bangerter filters) visual impairment. Text jittering markedly enhanced word recognition speed for people with severe visual loss (101 ± 25%), while for those with moderate visual impairment, this effect was weaker (19 ± 9%). The ability of low vision patients to discriminate the facial emotions of jittering images improved by a factor of 2. A prototype of optoelectronic jitter goggles produced similar improvement in facial emotion discrimination. Word recognition speed in participants with simulated visual impairment was enhanced for interjitter intervals over 100 ms and reduced for shorter intervals. Results suggest that retinal-image jitter with optimal frequency and amplitude is an effective strategy for enhancing visual information processing in the absence of spatial detail. These findings will enable the development of novel tools to improve the quality of life of low vision patients.

Estimated cases of blindness and visual impairment from neovascular age-related macular degeneration avoided in Australia by ranibizumab treatment.

PubMed

Mitchell, Paul; Bressler, Neil; Doan, Quan V; Dolan, Chantal; Ferreira, Alberto; Osborne, Aaron; Rochtchina, Elena; Danese, Mark; Colman, Shoshana; Wong, Tien Y

2014-01-01

Intravitreal injections of anti-vascular endothelial growth factor agents, such as ranibizumab, have significantly improved the management of neovascular age-related macular degeneration. This study used patient-level simulation modelling to estimate the number of individuals in Australia who would have been likely to avoid legal blindness or visual impairment due to neovascular age-related macular degeneration over a 2-year period as a result of intravitreal ranibizumab injections. The modelling approach used existing data for the incidence of neovascular age-related macular degeneration in Australia and outcomes from ranibizumab trials. Blindness and visual impairment were defined as visual acuity in the better-seeing eye of worse than 6/60 or 6/12, respectively. In 2010, 14,634 individuals in Australia were estimated to develop neovascular age-related macular degeneration who would be eligible for ranibizumab therapy. Without treatment, 2246 individuals would become legally blind over 2 years. Monthly 0.5 mg intravitreal ranibizumab would reduce incident blindness by 72% (95% simulation interval, 70-74%). Ranibizumab given as needed would reduce incident blindness by 68% (64-71%). Without treatment, 4846 individuals would become visually impaired over 2 years; this proportion would be reduced by 37% (34-39%) with monthly intravitreal ranibizumab, and by 28% (23-33%) with ranibizumab given as needed. These data suggest that intravitreal injections of ranibizumab, given either monthly or as needed, can substantially lower the number of cases of blindness and visual impairment over 2 years after the diagnosis of neovascular age-related macular degeneration.

Dorsal light response and changes of its responses under varying acceleration conditions

NASA Astrophysics Data System (ADS)

Watanabe, S.; Takabayashi, A.; Takagi, S.; von Baumgarten, R.; Wetzig, J.

In order to improve our understanding about functions of the gravity sensors, we have conducted four experiments in goldfish: 1) To define the effect of visual information influx on the static labyrinthine response, the dorsal light response (DLR) which had been proposed by von Holst as a model for postural adjustment in fish was reexamined with a newly designed, rotatory illumination device. The fish responded to illumination from the upper half of the visual field and a narrow range around 180 degrees of the lower half visual field. The maximal tilting angle of normal fish was about 40 degrees under horizontal illumination. 2) Under the changes of the gravito-inertial force level produced by a linear sled, the threshold of the gravity sensors was determined from postural adjustment responses. 3) Under hypogravic conditions during the parabolic flight of an airplane, the light-dependent behavior was investigated in intact and labyrinthectomized goldfish. 4) As one of the most likely candidates of the neural centers for the DLR, the valvula cerebelli, which receives its visual information not through the optic tectum but through the pretectal areas, is confirmed by the brain lesion experiments.

Effects of fatigue on driving performance under different roadway geometries: a simulator study.

PubMed

Du, Hongji; Zhao, Xiaohua; Zhang, Xingjian; Zhang, Yunlong; Rong, Jian

2015-01-01

This article examines the effects of fatigue on driving performance under different roadway geometries using a driving simulator. Twenty-four participants each completed a driving scenario twice: while alert and while experiencing fatigue. The driving scenario was composed of straight road segments and curves; there were 6 curves with 3 radius values (i.e., 200, 500, and 800 m) and 2 turning directions (i.e., left and right). Analysis was conducted on driving performance measures such as longitudinal speed, steering wheel movements, and lateral position. RESULTS confirmed that decremental changes in driving performance due to fatigue varied among road conditions. On straight segments, drivers' abilities to steer and maintain lane position were impaired, whereas on curves we found decremental changes in the quality of longitudinal speed as well as steering control and keeping the vehicle in the lane. Moreover, the effects of fatigue on driving performance were relative to the radius and direction of the curve. Fatigue impaired drivers' abilities to control the steering wheel, and the impairment proved more obvious on curves. The degree varied significantly as the curve radius changed. Drivers tended to drive closer to the right side due to fatigue, and the impairment in maintaining lane position became more obvious as the right-turn curve radius decreased. Driver fatigue has detrimental effects on driving performance, and the effects differ under different roadway geometries.

Does Simulator Sickness Impair Learning Decision Making While Driving a Police Vehicle? (Le mal du simulateur: un frein à l'apprentissage de la prise de décision en conduite d'un véhicule de police?)

ERIC Educational Resources Information Center

Paquette, Eve; Bélanger, Danielle-Claude

2015-01-01

The use of driving simulators is an innovation for police training in Quebec. There are some issues related to their impact on training objectives. This article presents the results of a study involving 71 police cadets who participated in six training sessions with a driving simulator. The training sessions were designed for developing the…

Integrating electronic patient records into a multi-media clinic-based simulation center using a PC blade platform: a foundation for a new pedagogy in dentistry.

PubMed

Taylor, David; Valenza, John A; Spence, James M; Baber, Randolph H

2007-10-11

Simulation has been used for many years in dental education, but the educational context is typically a laboratory divorced from the clinical setting, which impairs the transfer of learning. Here we report on a true simulation clinic with multimedia communication from a central teaching station. Each of the 43 fully-functioning student operatories includes a thin-client networked computer with access to an Electronic Patient Record (EPR).

Simulated astigmatism impairs academic-related performance in children.

PubMed

Narayanasamy, Sumithira; Vincent, Stephen J; Sampson, Geoff P; Wood, Joanne M

2015-01-01

Astigmatism is an important refractive condition in children. However, the functional impact of uncorrected astigmatism in this population is not well established, particularly with regard to academic performance. This study investigated the impact of simulated bilateral astigmatism on academic-related tasks before and after sustained near work in children. Twenty visually normal children (mean age: 10.8 ± 0.7 years; six males and 14 females) completed a range of standardised academic-related tests with and without 1.50 D of simulated bilateral astigmatism (with both academic-related tests and the visual condition administered in a randomised order). The simulated astigmatism was induced using a positive cylindrical lens while maintaining a plano spherical equivalent. Performance was assessed before and after 20 min of sustained near work, during two separate testing sessions. Academic-related measures included a standardised reading test (the Neale Analysis of Reading Ability), visual information processing tests (Coding and Symbol Search subtests from the Wechsler Intelligence Scale for Children) and a reading-related eye movement test (the Developmental Eye Movement test). Each participant was systematically assigned either with-the-rule (WTR, axis 180°) or against-the-rule (ATR, axis 90°) simulated astigmatism to evaluate the influence of axis orientation on any decrements in performance. Reading, visual information processing and reading-related eye movement performance were all significantly impaired by both simulated bilateral astigmatism (p < 0.001) and sustained near work (p < 0.001), however, there was no significant interaction between these factors (p > 0.05). Simulated astigmatism led to a reduction of between 5% and 12% in performance across the academic-related outcome measures, but there was no significant effect of the axis (WTR or ATR) of astigmatism (p > 0.05). Simulated bilateral astigmatism impaired children's performance on a range of academic-related outcome measures irrespective of the orientation of the astigmatism. These findings have implications for the clinical management of non-amblyogenic levels of astigmatism in relation to academic performance in children. Correction of low to moderate levels of astigmatism may improve the functional performance of children in the classroom. © 2014 The Authors Ophthalmic & Physiological Optics © 2014 The College of Optometrists.

System impairment compensation in coherent optical communications by using a bio-inspired detector based on artificial neural network and genetic algorithm

NASA Astrophysics Data System (ADS)

Wang, Danshi; Zhang, Min; Li, Ze; Song, Chuang; Fu, Meixia; Li, Jin; Chen, Xue

2017-09-01

A bio-inspired detector based on the artificial neural network (ANN) and genetic algorithm is proposed in the context of a coherent optical transmission system. The ANN is designed to mitigate 16-quadrature amplitude modulation system impairments, including linear impairment: Gaussian white noise, laser phase noise, in-phase/quadrature component imbalance, and nonlinear impairment: nonlinear phase. Without prior information or heuristic assumptions, the ANN, functioning as a machine learning algorithm, can learn and capture the characteristics of impairments from observed data. Numerical simulations were performed, and dispersion-shifted, dispersion-managed, and dispersion-unmanaged fiber links were investigated. The launch power dynamic range and maximum transmission distance for the bio-inspired method were 2.7 dBm and 240 km greater, respectively, than those of the maximum likelihood estimation algorithm. Moreover, the linewidth tolerance of the bio-inspired technique was 170 kHz greater than that of the k-means method, demonstrating its usability for digital signal processing in coherent systems.

Comparison of the Repeatable Battery for the Assessment of Neuropsychological Status Effort Scale and Effort Index in a Dementia Sample†

PubMed Central

Dunham, Kathryn J.; Shadi, Sarah; Sofko, Channing A.; Denney, Robert L.; Calloway, Jordan

2014-01-01

The aim of the current study was to compare two embedded measures of effort for the repeatable battery for the assessment of neuropsychological status (RBANS). Sensitivity and specificity of the Effort Index (EI) and Effort Scale (ES) were compared in a sample of individuals with genuine memory impairment (MI) and individuals coached to simulate MI. Overall, the EI yielded a sensitivity of 0.89 and specificity of 0.41, while the ES yielded a sensitivity of 0.88 and specificity of 0.81. When those in the MI group were separated by level of impairment, the EI was more specific when RBANS Total Scores were in the average or mildly impaired range, and the ES had greater specificity when RBANS Total Scores were in the severely impaired range. These results suggest that the embedded measure should be selected based on the level of impairment on the RBANS. PMID:25236719

A simulation study of the effects of alcohol on driving performance in a Chinese population.

PubMed

Li, Y C; Sze, N N; Wong, S C; Yan, Wei; Tsui, K L; So, F L

2016-10-01

Driving under the influence of alcohol (DUIA) is a significant factor contributing to road traffic crashes, injuries, and fatalities. Although the effects of alcohol on driving performance are widely acknowledged, studies of the effects of alcohol impairment on driving performance and particularly on the control system of Chinese adults are rare. This study attempts to evaluate the effects of alcohol on the driving performance of Chinese adults using a driving simulator. A double-blind experimental study was conducted to evaluate the effects of alcohol impairment on the driving performance of 52 Chinese participants using a driving simulator. A series of simulated driving tests covering two driving modules, including emergency braking (EB) and following braking (FB), at 50km/h and 80km/h were performed. Linear mixed models were established to evaluate driving performance in terms of braking reaction time (BRT), the standard deviation of lateral position (SD-LANE), and the standard deviation of speed (SD-SPEED). Driving performance in terms of BRT and SD-LANE was highly correlated with the level of alcohol consumption, with a one-unit increase in breath alcohol concentration (BrAC) degrading BRT and SD-LANE by 0.3% and 0.2%, respectively. Frequent drinkers generally reacted faster in their BRT than less-frequent drinkers and non-drinkers by 10.2% and 30.6%, respectively. Moreover, alcohol impairment had varying effects on certain aspects of the human control system, and automatic action was less likely to be affected than voluntary action from a psychological viewpoint. The findings should be useful for planning and developing effective measures to combat drink driving in Chinese communities. Copyright © 2016 Elsevier Ltd. All rights reserved.

Investigation of fiber dispersion impairment in 400GbE discrete multi-tone system for reach enhancement up to 40 km

NASA Astrophysics Data System (ADS)

Okabe, Ryo; Tanaka, Toshiki; Nishihara, Masato; Kai, Yutaka; Takahara, Tomoo; Chen, Hao; Yan, Weizhen; Tao, Zhenning; Rasmussen, Jens C.

2015-01-01

Discrete multi-tone (DMT) technology is an attractive modulation technique for short reach optical transmission system. One of the main factors that limit system performance is fiber dispersion, which is strongly influenced by the chirp characteristics of transmitters. We investigated the fiber dispersion impairment in a 400GbE (4 × 116.1-Gb/s) DMT system on LAN-WDM grid for reach enhancement up to 40 km through experiments and numerical simulations.

Dynamics of delayed pathogen infection models with pathogenic and cellular infections and immune impairment

NASA Astrophysics Data System (ADS)

Elaiw, A. M.; Raezah, A. A.; Alofi, B. S.

2018-02-01

We study the global dynamics of delayed pathogen infection models with immune impairment. Both pathogen-to-susceptible and infected-to-susceptible transmissions have been considered. Bilinear and saturated incidence rates are considered in the first and second model, respectively. We drive the basic reproduction parameter R0 which determines the global dynamics of models. Using Lyapunov method, we established the global stability of the models' steady states. The theoretical results are confirmed by numerical simulations.

Large predispersion for reduction of intrachannel nonlinear impairments in strongly dispersion-managed transmissions

NASA Astrophysics Data System (ADS)

Cao, Wenhua

2016-05-01

Predispersion for reduction of intrachannel nonlinear impairments in quasi-linear strongly dispersion-managed transmission system is analyzed in detail by numerical simulations. We show that for moderate amount of predispersion there is an optimal value at which reduction of the nonlinear impairments can be obtained, which is consistent with previous well-known predictions. However, we found that much better transmission performance than that of the previous predictions can be obtained if predispersion is increased to some extent. For large predispersion, the nonlinear impairments reduce monotonically with increasing predispersion and then they tend to be stabilized when predispersion is further increased. Thus, transmission performance can be efficiently improved by inserting a high-dispersive element, such as a chirped fiber bragg grating (CFBG), at the input end of the transmission link to broaden the signal pulses while, at the output end, using another CFBG with the opposite dispersion to recompress the signal.

Information entropy-based fitting of the disease trajectory of brain ischemia-induced vascular cognitive impairment.

PubMed

Liu, Lin; Huo, Ju; Zhao, Ying; Tian, Yu

2012-03-25

The present study investigated the disease trajectory of vascular cognitive impairment using the entropy of information in a neural network mathematical simulation based on the free radical and excitatory amino acids theories. Glutamate, malondialdehyde, and inducible nitric oxide synthase content was significantly elevated, but acetylcholine, catalase, superoxide dismutase, glutathione peroxidase and constitutive nitric oxide synthase content was significantly decreased in our vascular cognitive impairment model. The fitting curves for each factor were obtained using Matlab software. Nineteen, 30 and 49 days post ischemia were the main output time frames of the influence of these seven factors. Our results demonstrated that vascular cognitive impairment involves multiple factors. These factors include excitatory amino acid toxicity and nitric oxide toxicity. These toxicities disrupt the dynamic equilibrium of the production and removal of oxygen free radicals after cerebral ischemia, reducing the ability to clear oxygen free radicals and worsening brain injury.

Network and Atomistic Simulations Unveil the Structural Determinants of Mutations Linked to Retinal Diseases

PubMed Central

Mariani, Simona; Dell'Orco, Daniele; Felline, Angelo; Raimondi, Francesco; Fanelli, Francesca

2013-01-01

A number of incurable retinal diseases causing vision impairments derive from alterations in visual phototransduction. Unraveling the structural determinants of even monogenic retinal diseases would require network-centered approaches combined with atomistic simulations. The transducin G38D mutant associated with the Nougaret Congenital Night Blindness (NCNB) was thoroughly investigated by both mathematical modeling of visual phototransduction and atomistic simulations on the major targets of the mutational effect. Mathematical modeling, in line with electrophysiological recordings, indicates reduction of phosphodiesterase 6 (PDE) recognition and activation as the main determinants of the pathological phenotype. Sub-microsecond molecular dynamics (MD) simulations coupled with Functional Mode Analysis improve the resolution of information, showing that such impairment is likely due to disruption of the PDEγ binding cavity in transducin. Protein Structure Network analyses additionally suggest that the observed slight reduction of theRGS9-catalyzed GTPase activity of transducin depends on perturbed communication between RGS9 and GTP binding site. These findings provide insights into the structural fundamentals of abnormal functioning of visual phototransduction caused by a missense mutation in one component of the signaling network. This combination of network-centered modeling with atomistic simulations represents a paradigm for future studies aimed at thoroughly deciphering the structural determinants of genetic retinal diseases. Analogous approaches are suitable to unveil the mechanism of information transfer in any signaling network either in physiological or pathological conditions. PMID:24009494

Calf Muscle Oxygen Saturation During Six-Minute Walk Test And Its Relationship With Walking Impairment In Symptomatic Peripheral Artery Disease.

PubMed

Andrade-Lima, Aluísio; Cucato, Gabriel G; Domingues, Wagner J R; Germano-Soares, Antônio H; Cavalcante, Bruno R; Correia, Marilia A; Saes, Glauco F; Wolosker, Nelson; Gardner, Andrew W; Zerati, Antônio E; Ritti-Dias, Raphael M

2018-05-21

Impaired microcirculation is associated with poor walking capacity in symptomatic peripheral artery disease (PAD) patients during treadmill test, however, this test does not simulate the efforts of daily walking of these patients. Thus, the aim of the study was to describe the microcirculation responses during six-minute walk test (6MWT) and to analyze the relationship between microcirculation indicators and walking impairment in symptomatic PAD patients. Thirty-four patients were included (mean age = 67.6 ± 11.2). The clinical characteristics were collected and they performed a 6MWT in which initial claudication distance (ICD) and total walking distance (TWD) were recorded. During and after the 6MWT, calf muscle oxygen saturation (StO 2 ) parameters were monitored continuously to measure microcirculation behavior. The association between calf muscle StO 2 parameters and walking impairment was analyzed by Pearson or Spearman correlations. Walking impairment was not associated with any StO 2 parameters during exercise. In contrast, after 6MWT, recovery time of StO 2 (r = -0.472, P = .008) and recovery time to maximal StO 2 (r= -0.402, P = .019) were negatively correlated with ICD. Furthermore, the distance walked under claudication symptoms (ΔTWD - ICD) was positively correlated with recovery time to maximal StO 2 (r = 0.347, P = .048). In symptomatic PAD patients, shorter ICD values during a 6MWT are associated with a delayed recovery in calf muscle StO 2 after exercise. Calf muscle StO 2 parameters decrease subtly during 6MWT, suggesting that the degree of ischemia in the calf muscle during ground walking, simulating efforts of the daily walking, is relatively low. Copyright © 2018 Elsevier Inc. All rights reserved.

Medications and Impaired Driving: A Review of the Literature

PubMed Central

Hetland, Amanda; Carr, David B

2013-01-01

Objective To describe the association of specific medication classes with driving outcomes and provide clinical recommendations. Data sources The MEDLINE and EMBASE databases were searched for articles published from January 1973 to June 2013 on specific classes of medications known to be associated with driving impairment. The search included outcome terms such as automobile driving, motor vehicle crash, driving simulator, and road tests. Study selection and data extraction Only English-language articles that contained findings from observational or interventional designs were included. Cross-sectional studies, case series, and case reports were excluded. Studies of ≥ 10 subjects were included in this review. Data synthesis Driving is an important task and activity for the majority of adults. Unfortunately, some specific classes of commonly prescribed medications have been associated with driving impairment as measured by road performance, driving simulation, and/or motor vehicle crashes. This review of 30 studies identified findings with barbiturates, benzodiazepines, certain non-benzodiazepine hypnotics, various antidepressants, opioid and non-steroidal analgesics, anticonvulsants, antipsychotics, antiparkinsonian agents, skeletal muscle relaxants, antihistamines, anticholinergic medications, and hypoglycemic agents. Additional studies identifying medication impacts on sedation, sleep latency, and psychomotor function – as well as the role of alcohol – are also discussed. Conclusions Psychotropic agents and those with CNS side effects were associated with various measures of impaired driving performance. It is difficult to determine if such associations are actually a result of medication use or perhaps the medical diagnosis itself. Regardless, clinicians should be aware of the increased risk of impaired driving with specific populations and classes of medications when prescribing these agents, educate their patients, and/or consider safer alternatives. PMID:24473486

Feigning Amnesia Moderately Impairs Memory for a Mock Crime Video.

PubMed

Mangiulli, Ivan; van Oorsouw, Kim; Curci, Antonietta; Merckelbach, Harald; Jelicic, Marko

2018-01-01

Previous studies showed that feigning amnesia for a crime impairs actual memory for the target event. Lack of rehearsal has been proposed as an explanation for this memory-undermining effect of feigning. The aim of the present study was to replicate and extend previous research adopting a mock crime video instead of a narrative story. We showed participants a video of a violent crime. Next, they were requested to imagine that they had committed this offense and to either feign amnesia or confess the crime. A third condition was included: Participants in the delayed test-only control condition did not receive any instruction. On subsequent recall tests, participants in all three conditions were instructed to report as much information as possible about the offense. On the free recall test, feigning amnesia impaired memory for the video clip, but participants who were asked to feign crime-related amnesia outperformed controls. However, no differences between simulators and confessors were found on both correct cued recollection or on distortion and commission rates. We also explored whether inner speech might modulate memory for the crime. Inner speech traits were not found to be related to the simulating amnesia effect. Theoretical and practical implications of our results are discussed.

Auditory and tactile gap discrimination by observers with normal and impaired hearing.

PubMed

Desloge, Joseph G; Reed, Charlotte M; Braida, Louis D; Perez, Zachary D; Delhorne, Lorraine A; Villabona, Timothy J

2014-02-01

Temporal processing ability for the senses of hearing and touch was examined through the measurement of gap-duration discrimination thresholds (GDDTs) employing the same low-frequency sinusoidal stimuli in both modalities. GDDTs were measured in three groups of observers (normal-hearing, hearing-impaired, and normal-hearing with simulated hearing loss) covering an age range of 21-69 yr. GDDTs for a baseline gap of 6 ms were measured for four different combinations of 100-ms leading and trailing markers (250-250, 250-400, 400-250, and 400-400 Hz). Auditory measurements were obtained for monaural presentation over headphones and tactile measurements were obtained using sinusoidal vibrations presented to the left middle finger. The auditory GDDTs of the hearing-impaired listeners, which were larger than those of the normal-hearing observers, were well-reproduced in the listeners with simulated loss. The magnitude of the GDDT was generally independent of modality and showed effects of age in both modalities. The use of different-frequency compared to same-frequency markers led to a greater deterioration in auditory GDDTs compared to tactile GDDTs and may reflect differences in bandwidth properties between the two sensory systems.

The Impact of Ocular Pressures, Material Properties and Geometry on Optic Nerve Head Deformation

NASA Technical Reports Server (NTRS)

Feola, Andrew J.; Myers, Jerry G.; Raykin, Julia; Nelson, Emily S.; Samuels, Brian C.; Ethier C. Ross

2017-01-01

Alteration in intracranial pressure (ICP) has been associated with various diseases that cause visual impairment, including glaucoma, idiopathic intracranial hypertension and Visual Impairment and Intracranial Pressure (VIIP) syndrome. However, how changes in ICP lead to vision loss is unclear, although it is hypothesized to involve deformations of the tissues in the optic nerve head (ONH). Recently, understanding the effect of ICP alterations on ocular tissues has become a major concern for NASA, where 42 of astronauts that partake in long duration space missions suffer from VIIP syndrome. Astronauts with VIIP syndrome suffer from visual impairment and changes in ocular anatomy that persist after returning to earth (1). It is hypothesized that the cephalad fluid shift that occurs upon entering microgravity increases ICP, which leads to an altered biomechanical environment in the posterior globe and optic nerve sheath, and subsequently VIIP syndrome. Our goal was to develop a finite element (FE) model to simulate the acute effects of elevated ICP on the posterior eye. Here, we simulated how inter-individual differences affect the deformation of ONH tissues. Further, we examined how several different geometries influenced deformations when exposed to elevated ICP.

[Impairment of safety in navigation caused by alcohol: impact on visual function].

PubMed

Grütters, G; Reichelt, J A; Ritz-Timme, S; Thome, M; Kaatsch, H J

2003-05-01

So far in Germany, no legally binding standards for blood alcohol concentration exist that prove an impairment of navigability. The aim of our interdisciplinary project was to obtain data in order to identify critical blood alcohol limits. In this context the visual system seems to be of decisive importance. 21 professional skippers underwent realistic navigational demands soberly and alcoholized in a sea traffic simulator. The following parameters were considered: visual acuity, stereopsis, color vision, and accommodation. Under the influence of alcohol (average blood alcohol concentration: 1.08 per thousand ) each skipper considered himself to be completely capable of navigating. While simulations were running, all of the skippers made nautical mistakes or underestimated dangerous situations. Severe impairment in visual acuity or binocular function were not observed. Accommodation decreased by an average of 18% ( p=0.0001). In the test of color vision skippers made more mistakes ( p=0.017) and the time needed for this test was prolonged ( p=0.004). Changes in visual function as well as vegetative and psychological reactions could be the cause of mistakes and alcohol should therefore be regarded as a severe risk factor for security in sea navigation.

Distraction produces over-additive increases in the degree to which alcohol impairs driving performance.

PubMed

Van Dyke, Nicholas A; Fillmore, Mark T

2015-12-01

Research indicates that alcohol intoxication and increased demands on drivers' attention from distractions (e.g., passengers and cell phones) contribute to poor driving performance and increased rates of traffic accidents and fatalities. The present study examined the separate and combined effects of alcohol and distraction on simulated driving performance at blood alcohol concentrations (BrACs) below the legal driving limit in the USA (i.e., 0.08 %). Fifty healthy adult drivers (36 men and 14 women) were tested in a driving simulator following a 0.65-g/kg dose of alcohol and a placebo. Drivers completed two drive tests: a distracted drive, which included a two-choice detection task, and an undistracted control drive. Multiple indicators of driving performance, such as drive speed, within-lane deviation, steering rate, and lane exceedances were measured. Alcohol and distraction each impaired measures of driving performance. Moreover, the magnitude of alcohol impairment was increased by at least twofold when tested under the distracting versus the undistracted condition. The findings highlight the need for a clearer understanding of how common distractions impact intoxicated drivers, especially at BrACs that are currently legal for driving in the USA.

Detecting gait alterations due to concussion impairment with radar using information-theoretic techniques

NASA Astrophysics Data System (ADS)

Palmer, Jennifer; Bing, Kristin; Sharma, Amy; Greneker, Eugene; Selee, Teresa

2011-06-01

Several studies have shown that measuring changes in gait could provide an easier method of diagnosing and monitoring concussions. The purpose of this study was to measure radar signal returns to explore if differences in gait patterns between normal and "concussed" individuals could be identified from radar spectrogram data. Access to concussed individuals was not available during this feasibility study. Instead, based on research that demonstrated concussion impairment is equivalent to a blood alcohol content (BAC) of 0.05%, BAC impairment goggles were used to visually simulate a concussion. Both "impaired" and "not impaired" individuals were asked to complete only a motor skill task (walking) and then complete motor skill and cognitive skill (saying the months of the year in reverse order) tasks simultaneously. Results from the tests were analyzed using informationtheoretic (IT) techniques. IT algorithms were selected because of their potential to identify similarities and differences without having the requirement of a priori knowledge on an individual. To quantify results, two methods were incorporated: decision index, D(Q), analysis with receiver operating characteristic (ROC) curves and object-feature matrix clustering. Both techniques showed acceptable percent correctness in discriminating between normal and "impaired" individuals.

Visuospatial and Attentional Abilities Predict Driving Simulator Performance Among Older HIV-infected Adults

PubMed Central

Foley, J. M.; Gooding, A. L.; Thames, A. D.; Ettenhofer, M. L.; Kim, M. S.; Castellon, S. A.; Marcotte, T. D.; Sadek, J. R.; Heaton, R. K.; van Gorp, W. G.; Hinkin, C. H.

2013-01-01

Objectives To examine the effects of aging and neuropsychological (NP) impairment on driving simulator performance within a human immunodeficiency virus (HIV)-infected cohort. Methods Participants included 79 HIV-infected adults (n = 58 > age 50, n = 21 ≤ 40) who completed a NP battery and a personnel computer-based driving simulator task. Outcome variables included total completion time (time) and number of city blocks to complete the task (blocks). Results Compared to the younger group, the older group was less efficient in their route finding (blocks over optimum: 25.9 [20.1] vs 14.4 [16.9]; P = .02) and took longer to complete the task (time: 1297.6 [577.6] vs 804.4 [458.5] seconds; P = .001). Regression models within the older adult group indicated that visuospatial abilities (blocks: b = –0.40, P < .001; time: b = –0.40, P = .001) and attention (blocks: b = –0.49, P = .001; time: b = –0.42, P = .006) independently predicted simulator performance. The NP-impaired group performed more poorly on both time and blocks, compared to the NP normal group. Conclusions Older HIV-infected adults may be at risk of driving-related functional compromise secondary to HIV-associated neurocognitive decline. PMID:23314403

Novel Virtual User Models of Mild Cognitive Impairment for Simulating Dementia

PubMed Central

Segkouli, Sofia; Tzovaras, Dimitrios; Tsakiris, Thanos; Tsolaki, Magda; Karagiannidis, Charalampos

2015-01-01

Virtual user modeling research has attempted to address critical issues of human-computer interaction (HCI) such as usability and utility through a large number of analytic, usability-oriented approaches as cognitive models in order to provide users with experiences fitting to their specific needs. However, there is demand for more specific modules embodied in cognitive architecture that will detect abnormal cognitive decline across new synthetic task environments. Also, accessibility evaluation of graphical user interfaces (GUIs) requires considerable effort for enhancing ICT products accessibility for older adults. The main aim of this study is to develop and test virtual user models (VUM) simulating mild cognitive impairment (MCI) through novel specific modules, embodied at cognitive models and defined by estimations of cognitive parameters. Well-established MCI detection tests assessed users' cognition, elaborated their ability to perform multitasks, and monitored the performance of infotainment related tasks to provide more accurate simulation results on existing conceptual frameworks and enhanced predictive validity in interfaces' design supported by increased tasks' complexity to capture a more detailed profile of users' capabilities and limitations. The final outcome is a more robust cognitive prediction model, accurately fitted to human data to be used for more reliable interfaces' evaluation through simulation on the basis of virtual models of MCI users. PMID:26339282

Childhood adversities and adult psychopathology in the National Comorbidity Survey Replication (NCS-R) III: associations with functional impairment related to DSM-IV disorders.

PubMed

McLaughlin, K A; Green, J G; Gruber, M J; Sampson, N A; Zaslavsky, A M; Kessler, R C

2010-05-01

Despite evidence that childhood adversities (CAs) are associated with increased risk of mental disorders, little is known about their associations with disorder-related impairment. We report the associations between CAs and functional impairment associated with 12-month DSM-IV disorders in a national sample. We used data from the US National Comorbidity Survey Replication (NCS-R). Respondents completed diagnostic interviews that assessed 12-month DSM-IV disorder prevalence and impairment. Associations of 12 retrospectively reported CAs with impairment among cases (n=2242) were assessed using multiple regression analysis. Impairment measures included a dichotomous measure of classification in the severe range of impairment on the Sheehan Disability Scale (SDS) and a measure of self-reported number of days out of role due to emotional problems in the past 12 months. CAs were positively and significantly associated with impairment. Predictive effects of CAs on the SDS were particularly pronounced for anxiety disorders and were significant in predicting increased days out of role associated with mood, anxiety and disruptive behavior disorders. Predictive effects persisted throughout the life course and were not accounted for by disorder co-morbidity. CAs associated with maladaptive family functioning (MFF; parental mental illness, substance disorder, criminality, family violence, abuse, neglect) were more consistently associated with impairment than other CAs. The joint effects of co-morbid MFF CAs were significantly subadditive. Simulations suggest that CAs account for 19.6% of severely impairing disorders and 17.4% of days out of role. CAs predict greater disorder-related impairment, highlighting the ongoing clinical significance of CAs at every stage of the life course.

Use of the Hydrological Simulation Program-FORTRAN and bacterial source tracking for development of the fecal coliform total maximum daily load (TMDL) for Blacks Run, Rockingham County, Virginia

USGS Publications Warehouse

Moyer, Douglas; Hyer, Kenneth

2003-01-01

Impairment of surface waters by fecal coliform bacteria is a water-quality issue of national scope and importance. Section 303(d) of the Clean Water Act requires that each State identify surface waters that do not meet applicable water-quality standards. In Virginia, more than 175 stream segments are on the 1998 Section 303(d) list of impaired waters because of violations of the water-quality standard for fecal coliform bacteria. A total maximum daily load (TMDL) will need to be developed by 2006 for each of these impaired streams and rivers by the Virginia Departments of Environmental Quality and Conservation and Recreation. A TMDL is a quantitative representation of the maximum load of a given water-quality constituent, from all point and nonpoint sources, that a stream can assimilate without violating the designated water-quality standard. Blacks Run, in Rockingham County, Virginia, is one of the stream segments listed by the State of Virginia as impaired by fecal coliform bacteria. Watershed modeling and bacterial source tracking were used to develop the technical components of the fecal coliform bacteria TMDL for Accotink Creek. The Hydrological Simulation Program?FORTRAN (HSPF) was used to simulate streamflow, fecal coliform concentrations, and source-specific fecal coliform loading in Blacks Run. Ribotyping, a bacterial source tracking technique, was used to identify the dominant sources of fecal coliform bacteria in the Blacks Run watershed. Ribotyping also was used to determine the relative contributions of specific sources to the observed fecal coliform load in Blacks Run. Data from the ribotyping analysis were incorporated into the calibration of the fecal coliform model. Study results provide information regarding the calibration of the streamflow and fecal coliform bacteria models and also identify the reductions in fecal coliform loads required to meet the TMDL for Blacks Run. The calibrated streamflow model simulated observed streamflow characteristics with respect to total annual runoff, seasonal runoff, average daily streamflow, and hourly stormflow. The calibrated fecal coliform model simulated the patterns and range of observed fecal coliform bacteria concentrations. Observed fecal coliform bacteria concentrations during low-flow periods ranged from 40 to 7,000 colonies per 100 milliliters, and peak concentrations during storm-flow periods ranged from 33,000 to 260,000 colonies per 100 milliliters. Simulated source-specific contributions of fecal coliform bacteria to instream load were matched to the observed contributions from the dominant sources, which were cats, cattle, deer, dogs, ducks, geese, horses, humans, muskrats, poultry, raccoons, and sheep. According to model results, a 95-percent reduction in the current fecal coliform load delivered from the watershed to Blacks Run would result in compliance with the designated water-quality goals and associated TMDL.

Use of the Hydrological Simulation Program-FORTRAN and Bacterial Source Tracking for Development of the fecal coliform Total Maximum Daily Load (TMDL) for Accotink Creek, Fairfax County, Virginia

USGS Publications Warehouse

Moyer, Douglas; Hyer, Kenneth

2003-01-01

Impairment of surface waters by fecal coliform bacteria is a water-quality issue of national scope and importance. Section 303(d) of the Clean Water Act requires that each State identify surface waters that do not meet applicable water-quality standards. In Virginia, more than 175 stream segments are on the 1998 Section 303(d) list of impaired waters because of violations of the water-quality standard for fecal coliform bacteria. A total maximum daily load (TMDL) will need to be developed by 2006 for each of these impaired streams and rivers by the Virginia Departments of Environmental Quality and Conservation and Recreation. A TMDL is a quantitative representation of the maximum load of a given water-quality constituent, from all point and nonpoint sources, that a stream can assimilate without violating the designated water-quality standard. Accotink Creek, in Fairfax County, Virginia, is one of the stream segments listed by the State of Virginia as impaired by fecal coliform bacteria. Watershed modeling and bacterial source tracking were used to develop the technical components of the fecal coliform bacteria TMDL for Accotink Creek. The Hydrological Simulation Program?FORTRAN (HSPF) was used to simulate streamflow, fecal coliform concentrations, and source-specific fecal coliform loading in Accotink Creek. Ribotyping, a bacterial source tracking technique, was used to identify the dominant sources of fecal coliform bacteria in the Accotink Creek watershed. Ribotyping also was used to determine the relative contributions of specific sources to the observed fecal coliform load in Accotink Creek. Data from the ribotyping analysis were incorporated into the calibration of the fecal coliform model. Study results provide information regarding the calibration of the streamflow and fecal coliform bacteria models and also identify the reductions in fecal coliform loads required to meet the TMDL for Accotink Creek. The calibrated streamflow model simulated observed streamflow characteristics with respect to total annual runoff, seasonal runoff, average daily streamflow, and hourly stormflow. The calibrated fecal coliform model simulated the patterns and range of observed fecal coliform bacteria concentrations. Observed fecal coliform bacteria concentrations during low-flow periods ranged from 25 to 800 colonies per 100 milliliters, and peak concentrations during storm-flow periods ranged from 19,000 to 340,000 colonies per 100 milliliters. Simulated source-specific contributions of fecal coliform bacteria to instream load were matched to the observed contributions from the dominant sources, which were cats, deer, dogs, ducks, geese, humans, muskrats, and raccoons. According to model results, an 89-percent reduction in the current fecal coliform load delivered from the watershed to Accotink Creek would result in compliance with the designated water-quality goals and associated TMDL.

Face to face: blocking facial mimicry can selectively impair recognition of emotional expressions.

PubMed

Oberman, Lindsay M; Winkielman, Piotr; Ramachandran, Vilayanur S

2007-01-01

People spontaneously mimic a variety of behaviors, including emotional facial expressions. Embodied cognition theories suggest that mimicry reflects internal simulation of perceived emotion in order to facilitate its understanding. If so, blocking facial mimicry should impair recognition of expressions, especially of emotions that are simulated using facial musculature. The current research tested this hypothesis using four expressions (happy, disgust, fear, and sad) and two mimicry-interfering manipulations (1) biting on a pen and (2) chewing gum, as well as two control conditions. Experiment 1 used electromyography over cheek, mouth, and nose regions. The bite manipulation consistently activated assessed muscles, whereas the chew manipulation activated muscles only intermittently. Further, expressing happiness generated most facial action. Experiment 2 found that the bite manipulation interfered most with recognition of happiness. These findings suggest that facial mimicry differentially contributes to recognition of specific facial expressions, thus allowing for more refined predictions from embodied cognition theories.

Supertaskers: Profiles in extraordinary multitasking ability.

PubMed

Watson, Jason M; Strayer, David L

2010-08-01

Theory suggests that driving should be impaired for any motorist who is concurrently talking on a cell phone. But is everybody impaired by this dual-task combination? We tested 200 participants in a high-fidelity driving simulator in both single- and dual-task conditions. The dual task involved driving while performing a demanding auditory version of the operation span (OSPAN) task. Whereas the vast majority of participants showed significant performance decrements in dual-task conditions (compared with single-task conditions for either driving or OSPAN tasks), 2.5% of the sample showed absolutely no performance decrements with respect to performing single and dual tasks. In single-task conditions, these "supertaskers" scored in the top quartile on all dependent measures associated with driving and OSPAN tasks, and Monte Carlo simulations indicated that the frequency of supertaskers was significantly greater than chance. These individual differences help to sharpen our theoretical understanding of attention and cognitive control in naturalistic settings.

Concepts Within Reach: Action Performance Predicts Action Language Processing in Stroke

PubMed Central

Desai, Rutvik H.; Herter, Troy; Riccardi, Nicholas; Rorden, Chris; Fridriksson, Julius

2015-01-01

The relationship between the brain’s conceptual or semantic and sensory-motor systems remains controversial. Here, we tested manual and conceptual abilities of 41 chronic stroke patients in order to examine their relationship. Manual abilities were assed through a reaching task using an exoskeleton robot. Semantic abilities were assessed with implicit as well as explicit semantic tasks, for both verbs and nouns. The results show that that the degree of selective impairment for action word processing was predicted by the degree of impairment in reaching performance. Moreover, the implicit semantic measures showed a correlation with a global reaching parameter, while the explicit semantic similarity judgment task predicted performance in action initiation. These results indicate that action concepts are dynamically grounded through motoric simulations, and that more details are simulated for more explicit semantic tasks. This is evidence for a close and causal relationship between sensory-motor and conceptual systems of the brain. PMID:25858602

Dammarane Sapogenins Ameliorates Neurocognitive Functional Impairment Induced by Simulated Long-Duration Spaceflight.

PubMed

Wu, Xiaorui; Li, Dong; Liu, Junlian; Diao, Lihong; Ling, Shukuan; Li, Yuheng; Gao, Jianyi; Fan, Quanchun; Sun, Weijia; Li, Qi; Zhao, Dingsheng; Zhong, Guohui; Cao, Dengchao; Liu, Min; Wang, Jiaping; Zhao, Shuang; Liu, Yu; Bai, Guie; Shi, Hongzhi; Xu, Zi; Wang, Jing; Xue, Chunmei; Jin, Xiaoyan; Yuan, Xinxin; Li, Hongxing; Liu, Caizhi; Sun, Huiyuan; Li, Jianwei; Li, Yongzhi; Li, Yingxian

2017-01-01

Increasing evidence indicates the occurrence of cognitive impairment in astronauts under spaceflight compound conditions, but the underlying mechanisms and countermeasures need to be explored. In this study, we found that learning and memory abilities were significantly reduced in rats under a simulated long-duration spaceflight environment (SLSE), which includes microgravity, isolation confinement, noises, and altered circadian rhythms. Dammarane sapogenins (DS), alkaline hydrolyzed products of ginsenosides, can enhance cognition function by regulating brain neurotransmitter levels and inhibiting SLSE-induced neuronal injury. Bioinformatics combined with experimental verification identified that the PI3K-Akt-mTOR pathway was inhibited and the MAPK pathway was activated during SLSE-induced cognition dysfunction, whereas DS substantially ameliorated the changes in brain. These findings defined the characteristics of SLSE-induced cognitive decline and the mechanisms by which DS improves it. The results provide an effective candidate for improving cognitive function in spaceflight missions.

Dammarane Sapogenins Ameliorates Neurocognitive Functional Impairment Induced by Simulated Long-Duration Spaceflight

PubMed Central

Wu, Xiaorui; Li, Dong; Liu, Junlian; Diao, Lihong; Ling, Shukuan; Li, Yuheng; Gao, Jianyi; Fan, Quanchun; Sun, Weijia; Li, Qi; Zhao, Dingsheng; Zhong, Guohui; Cao, Dengchao; Liu, Min; Wang, Jiaping; Zhao, Shuang; Liu, Yu; Bai, Guie; Shi, Hongzhi; Xu, Zi; Wang, Jing; Xue, Chunmei; Jin, Xiaoyan; Yuan, Xinxin; Li, Hongxing; Liu, Caizhi; Sun, Huiyuan; Li, Jianwei; Li, Yongzhi; Li, Yingxian

2017-01-01

Increasing evidence indicates the occurrence of cognitive impairment in astronauts under spaceflight compound conditions, but the underlying mechanisms and countermeasures need to be explored. In this study, we found that learning and memory abilities were significantly reduced in rats under a simulated long-duration spaceflight environment (SLSE), which includes microgravity, isolation confinement, noises, and altered circadian rhythms. Dammarane sapogenins (DS), alkaline hydrolyzed products of ginsenosides, can enhance cognition function by regulating brain neurotransmitter levels and inhibiting SLSE-induced neuronal injury. Bioinformatics combined with experimental verification identified that the PI3K-Akt-mTOR pathway was inhibited and the MAPK pathway was activated during SLSE-induced cognition dysfunction, whereas DS substantially ameliorated the changes in brain. These findings defined the characteristics of SLSE-induced cognitive decline and the mechanisms by which DS improves it. The results provide an effective candidate for improving cognitive function in spaceflight missions. PMID:28611667

The effects of alcohol on driver performance in a decision making situation

NASA Technical Reports Server (NTRS)

Allen, R. W.; Schwartz, S. H.; Stein, A. C.; Hogge, J. R.

1978-01-01

The results are reviewed of driving simulator and in-vehicle field test experiments of alcohol effects on driver risk taking. The objective was to investigate changes in risk taking under alcoholic intoxication and relate these changes to effects on traffic safety. The experiments involved complex 15 minute driving scenarios requiring decision making and steering and speed control throughout a series of typical driving situations. Monetary rewards and penalties were employed to simulate the real-world motivations inherent in driving. A full placebo experimental design was employed, and measures related to traffic safety, driver/vehicle performance and driver behavior were obtained. Alcohol impairment was found to increase the rate of accidents and speeding tickets. Behavioral measures showed these traffic safety effects to be due to impaired psychomotor performance and perceptual distortions. Subjective estimates of risk failed to show any change in the driver's willingness to take risks when intoxicated.

Acute tolerance to alcohol impairment of behavioral and cognitive mechanisms related to driving: drinking and driving on the descending limb.

PubMed

Weafer, Jessica; Fillmore, Mark T

2012-04-01

Alcohol effects on behavioral and cognitive mechanisms influence impaired driving performance and decisions to drive after drinking (Barry 1973; Moskowitz and Robinson 1987). To date, research has focused on the ascending limb of the blood alcohol curve, and there is little understanding of how acute tolerance to impairment of these mechanisms might influence driving behavior on the descending limb. To provide an integrated examination of the degree to which alcohol impairment of motor coordination and inhibitory control contributes to driving impairment and decisions to drive on the ascending and descending limbs of the blood alcohol curve. Social-drinking adults (N = 20) performed a testing battery that measured simulated driving performance and willingness to drive, as well as mechanisms related to driving: motor coordination (grooved pegboard), inhibitory control (cued go/no-go task), and subjective intoxication. Performance was tested in response to placebo and a moderate dose of alcohol (0.65 g/kg) twice at comparable blood alcohol concentrations: once on the ascending limb and again on the descending limb. Impaired motor coordination and subjective intoxication showed acute tolerance, whereas driving performance and inhibitory control showed no recovery from impairment. Greater motor impairment was associated with poorer driving performance under alcohol, and poorer inhibitory control was associated with more willingness to drive. Findings suggest that acute tolerance to impairment of motor coordination is insufficient to promote recovery of driving performance and that the persistence of alcohol-induced disinhibition might contribute to risky decisions to drive on the descending limb.

Acute tolerance to alcohol impairment of behavioral and cognitive mechanisms related to driving: drinking and driving on the descending limb

PubMed Central

Weafer, Jessica

2015-01-01

Rationale Alcohol effects on behavioral and cognitive mechanisms influence impaired driving performance and decisions to drive after drinking (Barry 1973; Moskowitz and Robinson 1987). To date, research has focused on the ascending limb of the blood alcohol curve, and there is little understanding of how acute tolerance to impairment of these mechanisms might influence driving behavior on the descending limb. Objectives To provide an integrated examination of the degree to which alcohol impairment of motor coordination and inhibitory control contributes to driving impairment and decisions to drive on the ascending and descending limbs of the blood alcohol curve. Methods Social-drinking adults (N=20) performed a testing battery that measured simulated driving performance and willingness to drive, as well as mechanisms related to driving: motor coordination (grooved pegboard), inhibitory control (cued go/no-go task), and subjective intoxication. Performance was tested in response to placebo and a moderate dose of alcohol (0.65 g/kg) twice at comparable blood alcohol concentrations: once on the ascending limb and again on the descending limb. Results Impaired motor coordination and subjective intoxication showed acute tolerance, whereas driving performance and inhibitory control showed no recovery from impairment. Greater motor impairment was associated with poorer driving performance under alcohol, and poorer inhibitory control was associated with more willingness to drive. Conclusions Findings suggest that acute tolerance to impairment of motor coordination is insufficient to promote recovery of driving performance and that the persistence of alcohol-induced disinhibition might contribute to risky decisions to drive on the descending limb. PMID:21960182

The role of visual attention in predicting driving impairment in older adults.

PubMed

Hoffman, Lesa; McDowd, Joan M; Atchley, Paul; Dubinsky, Richard

2005-12-01

This study evaluated the role of visual attention (as measured by the DriverScan change detection task and the Useful Field of View Test [UFOV]) in the prediction of driving impairment in 155 adults between the ages of 63 and 87. In contrast to previous research, participants were not oversampled for visual impairment or history of automobile accidents. Although a history of automobile accidents within the past 3 years could not be predicted using any variable, driving performance in a low-fidelity simulator could be significantly predicted by performance in the change detection task and by the divided and selection attention subtests of the UFOV in structural equation models. The sensitivity and specificity of each measure in identifying at-risk drivers were also evaluated with receiver operating characteristic curves.

On-Line Safe Flight Envelope Determination for Impaired Aircraft

NASA Technical Reports Server (NTRS)

Lombaerts, Thomas; Schuet, Stefan; Acosta, Diana; Kaneshige, John

2015-01-01

The design and simulation of an on-line algorithm which estimates the safe maneuvering envelope of aircraft is discussed in this paper. The trim envelope is estimated using probabilistic methods and efficient high-fidelity model based computations of attainable equilibrium sets. From this trim envelope, a robust reachability analysis provides the maneuverability limitations of the aircraft through an optimal control formulation. Both envelope limits are presented to the flight crew on the primary flight display. In the results section, scenarios are considered where this adaptive algorithm is capable of computing online changes to the maneuvering envelope due to impairment. Furthermore, corresponding updates to display features on the primary flight display are provided to potentially inform the flight crew of safety critical envelope alterations caused by the impairment.

Human Research Program Integrated Research Plan. Revision C

NASA Technical Reports Server (NTRS)

Steinberg, Susan

2011-01-01

Crew health and performance are critical to successful human exploration beyond low Earth orbit. The Human Research Program (HRP) is essential to enabling extended periods of space exploration because it provides knowledge and tools to mitigate risks to human health and performance. Risks include physiological effects from radiation and hypogravity environments, as well as unique challenges in medical support, human factors, and behavioral or psychological factors. The Human Research Program (HRP) delivers human health and performance countermeasures, knowledge, technologies and tools to enable safe, reliable, and productive human space exploration. Without HRP results, NASA will face unknown and unacceptable risks for mission success and post-mission crew health. This Integrated Research Plan (IRP) describes (1) HRP's approach and research activities that are intended to address the needs of human space exploration and serve HRP customers and (2) the method of integration for risk mitigation. The scope of the IRP is limited to the activities that can be conducted with the resources available to the HRP; it does not contain activities that would be performed if additional resources were available. The timescale of human space exploration is envisioned to take many decades. The IRP illustrates the program s research plan through the timescale of early lunar missions of extended duration.

Impact of Age and Hearing Impairment on Work Performance during Long Working Hours

PubMed Central

Grossi, Nina R.; Kallus, K. Wolfgang

2018-01-01

Based on demographic prognoses, it must be assumed that a greater number of older workers will be found in the future labor market. How to deal with their possible age-related impairments of sensory functions, like hearing impairment and work performance during extended working time, has not been addressed explicitly until now. The study addresses this interplay. The study was performed on two consecutive days after normal working hours. The 55 participants had to “work” in the study at least three additional hours to simulate a situation of long working hours. The tested measures for (job) performance were: general attention, long-term selective attention, concentration, and reaction time. All of the investigated variables were taken at both days of the study (2 × 2 × 2 repeated measurement design). The results show effects for age, the interaction of hearing impairment and time of measurement, and effects of the measurement time. Older participants reacted slower than younger participants did. Furthermore, younger participants reacted more frequently in a correct way. Hearing impairment seems to have a negative impact especially on measures of false reactions, and therefore especially on measurement time 1. The results can be interpreted in a way that hearing-impaired participants are able to compensate their deficits over time. PMID:29315260

Impact of Age and Hearing Impairment on Work Performance during Long Working Hours.

PubMed

Wagner-Hartl, Verena; Grossi, Nina R; Kallus, K Wolfgang

2018-01-09

Based on demographic prognoses, it must be assumed that a greater number of older workers will be found in the future labor market. How to deal with their possible age-related impairments of sensory functions, like hearing impairment and work performance during extended working time, has not been addressed explicitly until now. The study addresses this interplay. The study was performed on two consecutive days after normal working hours. The 55 participants had to "work" in the study at least three additional hours to simulate a situation of long working hours. The tested measures for (job) performance were: general attention, long-term selective attention, concentration, and reaction time. All of the investigated variables were taken at both days of the study (2 × 2 × 2 repeated measurement design). The results show effects for age, the interaction of hearing impairment and time of measurement, and effects of the measurement time. Older participants reacted slower than younger participants did. Furthermore, younger participants reacted more frequently in a correct way. Hearing impairment seems to have a negative impact especially on measures of false reactions, and therefore especially on measurement time 1. The results can be interpreted in a way that hearing-impaired participants are able to compensate their deficits over time.

Development and Evaluation of Fault-Tolerant Flight Control Systems

NASA Technical Reports Server (NTRS)

Song, Yong D.; Gupta, Kajal (Technical Monitor)

2004-01-01

The research is concerned with developing a new approach to enhancing fault tolerance of flight control systems. The original motivation for fault-tolerant control comes from the need for safe operation of control elements (e.g. actuators) in the event of hardware failures in high reliability systems. One such example is modem space vehicle subjected to actuator/sensor impairments. A major task in flight control is to revise the control policy to balance impairment detectability and to achieve sufficient robustness. This involves careful selection of types and parameters of the controllers and the impairment detecting filters used. It also involves a decision, upon the identification of some failures, on whether and how a control reconfiguration should take place in order to maintain a certain system performance level. In this project new flight dynamic model under uncertain flight conditions is considered, in which the effects of both ramp and jump faults are reflected. Stabilization algorithms based on neural network and adaptive method are derived. The control algorithms are shown to be effective in dealing with uncertain dynamics due to external disturbances and unpredictable faults. The overall strategy is easy to set up and the computation involved is much less as compared with other strategies. Computer simulation software is developed. A serious of simulation studies have been conducted with varying flight conditions.

Feigning Amnesia Moderately Impairs Memory for a Mock Crime Video

PubMed Central

Mangiulli, Ivan; van Oorsouw, Kim; Curci, Antonietta; Merckelbach, Harald; Jelicic, Marko

2018-01-01

Previous studies showed that feigning amnesia for a crime impairs actual memory for the target event. Lack of rehearsal has been proposed as an explanation for this memory-undermining effect of feigning. The aim of the present study was to replicate and extend previous research adopting a mock crime video instead of a narrative story. We showed participants a video of a violent crime. Next, they were requested to imagine that they had committed this offense and to either feign amnesia or confess the crime. A third condition was included: Participants in the delayed test-only control condition did not receive any instruction. On subsequent recall tests, participants in all three conditions were instructed to report as much information as possible about the offense. On the free recall test, feigning amnesia impaired memory for the video clip, but participants who were asked to feign crime-related amnesia outperformed controls. However, no differences between simulators and confessors were found on both correct cued recollection or on distortion and commission rates. We also explored whether inner speech might modulate memory for the crime. Inner speech traits were not found to be related to the simulating amnesia effect. Theoretical and practical implications of our results are discussed. PMID:29760675

Distraction produces over-additive increases in the degree to which alcohol impairs driving performance

PubMed Central

Van Dyke, Nicholas A.; Fillmore, Mark T.

2015-01-01

Rationale Research indicates that alcohol intoxication and increased demands on drivers’ attention from distractions (e.g. passengers and cell phones) contribute to poor driving performance and increased rates of traffic accidents and fatalities. Objectives The present study examined the separate and combined effects of alcohol and distraction on simulated driving performance at blood alcohol concentrations (BrACs) below the legal driving limit in the United States (i.e. 0.08%). Methods Fifty healthy adult drivers (36 men and 14 women) were tested in a driving simulator following a 0.65 g/kg dose of alcohol and a placebo. Drivers completed two drive tests; a distracted drive, which included a two-choice detection task, and an undistracted control drive. Multiple indicators of driving performance, such as drive speed, within-lane deviation, steering rate, and lane exceedances were measured. Results Alcohol and distraction each impaired measures of driving performance. Moreover, the magnitude of alcohol impairment was increased by at least two-fold when tested under the distracting versus the undistracted condition. Conclusions The findings highlight the need for a clearer understanding of how common distractions impact intoxicated drivers, especially at BrACs that are currently legal for driving in the United States. PMID:26349918

The impairing effects of mental fatigue on response inhibition: An ERP study

PubMed Central

Guo, Zizheng; Chen, Ruiya; Liu, Xian; Zheng, Yan; Gong, Mingliang; Zhang, Jun

2018-01-01

Mental fatigue is one of the main reasons for the decline of response inhibition. This study aimed to explore the impairing influence of mental fatigue on a driver’s response inhibition. The effects of mental fatigue on response inhibition were assessed by comparing brain activity and behavioral indices when performing a Go/NoGo task before and after a 90-min fatigue manipulation task. Participants in the driving group performed a simulated driving task, while individuals in the control group spent the same time watching movies. We found that participants in the driving group reported higher levels of mental fatigue and had a higher percentage of eye closure and larger lateral deviations from their lane positions, which indicated there was effective manipulation of mental fatigue through a prolonged simulated driving task. After manipulation of mental fatigue, we observed increased reaction time and miss rates, delayed NoGo-N2 latency and Go-P3 latency, and decreased NoGo-P3 amplitude, which indicated that mental fatigue may slow down the speed of the inhibition process, delay the evaluation of visual stimuli and reduce the availability of attentional resources. These findings revealed the underlying neurological mechanisms of how mental fatigue impaired response inhibition. PMID:29856827

Biomechanical analysis of the influence of friction in jaw joint disorders.

PubMed

Koolstra, J H

2012-01-01

Increased friction due to impaired lubrication in the jaw joint has been considered as one of the possible causes for internal joint disorders. A very common internal disorder in the jaw joint is an anteriorly dislocated articular disc. This is generally considered to contribute to the onset of arthritic injuries. Increase of friction as caused by impairment of lubrication is suspected to be a possible cause for such a disorder. The influence of friction was addressed by analysis of its effects on tensions and deformations of the cartilaginous structures in the jaw joint using computational biomechanical analysis. Jaw open-close movements were simulated while in one or two compartments of the right joint friction was applied in the articular contact. The left joint was treated as the healthy control. The simulations predicted that friction primarily causes increased shear stress in the articular cartilage layers, but hardly in the articular disc. This suggests that impaired lubrication may facilitate deterioration of the cartilage-subchondral bone unit of the articular surfaces. The results further suggest that increased friction is not a plausible cause for turning a normally functioning articular disc into an anteriorly dislocated one. Copyright © 2011 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

An assessment of driving fitness in patients with visual impairment to understand the elevated risk of motor vehicle accidents

PubMed Central

Kunimatsu-Sanuki, Shiho; Iwase, Aiko; Araie, Makoto; Aoki, Yuki; Hara, Takeshi; Nakazawa, Toru; Yamaguchi, Takuhiro; Ono, Hiroshi; Sanuki, Tomoyuki; Itoh, Makoto

2015-01-01

Objective To assess the driving fitness of patients with glaucoma by identifying specific areas and degrees of visual field impairment that threaten safe driving. Design Case–control study. Setting, and participants This prospective study included 36 patients with advanced glaucoma, defined as Humphrey field analyzer (HFA; 24-2 SITA standard program) measurements of mean deviation in both eyes of worse than −12 dB, and 36 age-matched and driving exposure time-matched normal subjects. All participants underwent testing in a novel driving simulator (DS) system. Participants were recruited between September 2010 and January 2012. Main outcome measures The number of collisions with simulated hazards and braking response time in 14 DS scenarios was recorded. Monocular HFA 24-2 test results from both eyes were merged to calculate the binocular integrated visual field (IVF). The position of the IVF subfields in which the collision-involved patients had lower sensitivity than the collision-uninvolved patients was compared with the track of the hazard. The cut-off value to predict an elevated risk of collisions was determined, as were its sensitivity and specificity, with the area under the receiver operating characteristic (AUROC) curve. Results Patients with advanced glaucoma were involved in a significantly higher number of collisions in the DS than the age-matched and driving exposure time-matched normal subjects (119 vs 40, respectively, p<0.0001), especially in four specific DS scenarios. In these four scenarios, IVF sensitivity was significantly lower in the collision-involved patients than in the collision-uninvolved patients in subfields on or near the track of the simulated hazard (p<0.05). The subfields with the largest AUROC curve had values ranging from 0.72 to 0.91 and were located in the paracentral visual field just below the horizontal. Conclusions Our novel DS system effectively assessed visual impairment, showing that simulators may have future potential in educating patients. PMID:25724982

Effects of different blood alcohol concentrations and post-alcohol impairment on driving behavior and task performance.

PubMed

Liu, Yung-Ching; Ho, Chin Heng

2010-08-01

A study using simulator methodology was conducted to investigate the effects of (1) different blood alcohol concentrations (BAC) of 0, 0.05, 0.08, and 0.10 percent and (2) post-alcohol impairment (where BAC approximately 0%) on driving behavior and subsidiary cognitive task performance. Two driving sessions were investigated, that is, drunk driving and post-alcohol driving, with each requiring approximately 20 min of driving. In addition to driving safely, participants were instructed to perform the critical flicker fusion (CFF) test and completed the NASA-TLX mental workload questionnaire. Eight licensed drivers (6 males, 2 females) participated in this 2 (road complexities) x 2 (simulated driving sessions) x 4 (levels of BAC) within-subjects experiment. The study revealed that higher BAC levels were associated with lower performing driving behavior. The driver's mental workload reached the highest values in the post-alcohol session. In terms of tasks involving divided attention, the traffic sign distance estimation showed significant deterioration with increased BAC levels. The relationship between drunk-driving behavior and alcohol dosage was supported in this study. Noticeably, no significant difference was found between drunk driving and post-alcohol driving, indicating that even in the post-alcohol situation, the impairment still remained significant enough to jeopardize traffic safety as much as it does in the case of drunk driving. In real-life situations, adopting a rest-time strategy to avoid post-alcohol impairment effects may not be the most appropriate solution by drivers; rather, drivers should be given some tests to verify the probability of post-alcohol effects on driving.

Influence of simulated microgravity on the sympathetic response to exercise

NASA Technical Reports Server (NTRS)

Woodman, C. R.; Kregel, K. C.; Tipton, C. M.

1997-01-01

Rats exposed to simulated conditions of microgravity exhibit reductions in aerobic exercise capacity that may be due to an impaired ability of the sympathetic nervous system (SNS) to mediate an increase in cardiac output and to redistribute blood flow. The purpose of this study was to quantify the sympathetic response to exercise in rats after exposure to 14 days of simulated microgravity or control conditions. To achieve this aim, rats were exposed to 14 days of head-down suspension (HDS) or cage control (CC) conditions. On day 14, norepinephrine (NE) synthesis was blocked with alpha-methyl-p-tyrosine, and the rate of NE depletion after synthesis blockade was used to estimate SNS activity in the left ventricle, spleen, and soleus muscle during treadmill exercise at 75% of maximal oxygen uptake. When compared with CC rats, the sympathetic response to exercise in HDS rats was characterized by a lower rate of NE depletion in the left ventricle (-82%) and spleen (-42%). The rate of NE depletion in the soleus muscle was 47% higher. These differences could contribute to the decrement in aerobic capacity of HDS rats by impairing their ability to augment cardiac output and to redirect blood flow to actively contracting skeletal muscle during exercise.

Radiation effects control: Eyes, skin. [space environment simulation

NASA Technical Reports Server (NTRS)

Hightower, D.; Smathers, J. B.

1974-01-01

Adverse effects on the lens of the eye and the skin due to exposure to proton radiation during manned space flight were evaluated. Actual proton irradiation which might be encountered in space was simulated. Irradiation regimes included single acute exposures, daily fractionated exposures, and weekly fractionated exposures. Animals were exposed and then maintained and examined periodically until data sufficient to meet the objective were obtained. No significant skin effects were noted and no serious sight impairment was exhibited.

Simulating Category Learning and Set Shifting Deficits in Patients Weight-Restored from Anorexia Nervosa

DTIC Science & Technology

2014-01-01

Neuropsychology, in press     Simulating Category Learning and Set Shifting Deficits in Patients Weight-Restored from Anorexia Nervosa J...University   Objective: To examine set shifting in a group of women previously diagnosed with anorexia nervosa (AN) who are now weight-restored (AN-WR...participant fails to switch to the new rule but rather persists with the previously correct rule. Adult patients with Anorexia Nervosa (AN) are often impaired

Effects of prolonged wakefulness combined with alcohol and hands-free cell phone divided attention tasks on simulated driving.

PubMed

Iudice, A; Bonanni, E; Gelli, A; Frittelli, C; Iudice, G; Cignoni, F; Ghicopulos, I; Murri, L

2005-03-01

Simulated driving ability was assessed following administration of alcohol, at an estimated blood level of 0.05%, and combined prolonged wakefulness, while participants were undertaking divided attention tasks over a hands-free mobile phone. Divided attention tasks were structured to provide a sustained cognitive workload to the subjects. Twenty three young healthy individuals drove 10 km simulated driving under four conditions in a counterbalanced, within-subject design: alcohol, alcohol and 19 h wakefulness, alcohol and 24 h wakefulness, and while sober. Study measures were: simulated driving, self-reported sleepiness, critical flicker fusion threshold (CFFT), Stroop word-colour interference test (Stroop) and simple visual reaction times (SVRT). As expected, subjective sleepiness was highly correlated with both sleep restriction and alcohol consumption. The combination of alcohol and 24 h sustained wakefulness produced the highest driving impairment, significantly beyond the alcohol effect itself. Concurrent alcohol and 19 h wakefulness significantly affected only driving time-to-collision. No significant changes of study measures occurred following alcohol intake in unrestricted sleep conditions. CFFT, SVRT and Stroop results showed a similar trend in the four study conditions. Thus apparently 'safe' blood alcohol levels in combination with prolonged wakefulness resulted in significant driving impairments. In normal sleep conditions alcohol effects on driving were partially counteracted by the concomitant hands-free phone based psychometric tasks. 2005 John Wiley & Sons, Ltd.

Acute fatigue impairs neuromuscular activity of anterior cruciate ligament-agonist muscles in female team handball players.

PubMed

Zebis, M K; Bencke, J; Andersen, L L; Alkjaer, T; Suetta, C; Mortensen, P; Kjaer, M; Aagaard, P

2011-12-01

In sports, like team handball, fatigue has been associated with an increased risk of anterior cruciate ligament (ACL) injury. While effects of fatigue on muscle function are commonly assessed during maximal isometric voluntary contraction (MVC), such measurements may not relate to the muscle function during match play. The purpose of this study was to investigate the effect of muscle fatigue induced by a simulated handball match on neuromuscular strategy during a functional sidecutting movement, associated with the incidence of ACL injury. Fourteen female team handball players were tested for neuromuscular activity [electromyography (EMG)] during a sidecutting maneuver on a force plate, pre and post a simulated handball match. MVC was obtained during maximal isometric quadriceps and hamstring contraction. The simulated handball match consisted of exercises mimicking handball match activity. Whereas the simulated handball match induced a decrease in MVC strength for both the quadriceps and hamstring muscles (P<0.05), a selective decrease in hamstring neuromuscular activity was seen during sidecutting (P<0.05). This study shows impaired ACL-agonist muscle (i.e. hamstring) activity during sidecutting in response to acute fatigue induced by handball match play. Thus, screening procedures should involve functional movements to reveal specific fatigue-induced deficits in ACL-agonist muscle activation during high-risk phases of match play. © 2010 John Wiley & Sons A/S.

Artificial Gravity Research Project

NASA Technical Reports Server (NTRS)

Kamman, Michelle R.; Paloski, William H.

2005-01-01

Protecting the health, safety, and performance of exploration-class mission crews against the physiological deconditioning resulting from long-term weightlessness during transit and long-term hypogravity during surface operations will require effective, multi-system countermeasures. Artificial gravity (AG), which would replace terrestrial gravity with inertial forces generated by rotating the transit vehicle or by a human centrifuge device within the transit vehicle or surface habitat, has long been considered a potential solution. However, despite its attractiveness as an efficient, multi-system countermeasure and its potential for improving the environment and simplifying operational activities (e.g., WCS, galley, etc.), much still needs to be learned regarding the human response to rotating environments before AG can be successfully implemented. This paper will describe our approach for developing and implementing a rigorous AG Research Project to address the key biomedical research questions that must be answered before developing effective AG countermeasure implementation strategies for exploration-class missions. The AG Research Project will be performed at JSC, ARC, extramural academic and government research venues, and international partner facilities maintained by DLR and IMBP. The Project includes three major ground-based human research subprojects that will lead to flight testing of intermittent short-radius AG in ISS crewmembers after 201 0, continuous long-radius AG in CEV crews transiting to and from the Moon, and intermittent short-radius AG plus exercise in lunar habitats. These human ground-based subprojects include: 1) a directed, managed international short-radius project to investigate the multi-system effectiveness of intermittent AG in human subjects deconditioned by bed rest, 2) a directed, managed long-radius project to investigate the capacity of humans to live and work for extended periods in rotating environments, and 3) a focused, investigator-initiated project to investigate system-specific adaptation to and from rotating environments. The AG Research Project also includes two major animal research subprojects: 1) a directed, managed ground-based subproject using rodents and, possibly, sub-human primates, to address mechanistic issues that cannot be studied in humans, to rapidly develop higher sample numbers than can be achieved in the human subprojects, and to establish feasible parameter operating bands to reduce the breadth of the human subprojects, and 2) a flight subproject using rodents to estimate the physiological effects of long term exposure to hypogravity and to investigate the effects of contamination by terrestrial gravity in estimating AG effectiveness. The animal flight subproject would be performed aboard ISS using the CAM module in approximately the 2008-201 1 timeframe. The paper will first present an overview of the key biomedical research questions to be answered. It will then describe the overall approaches to be utilized in developing and implementing the AG Research Project, including definition of the intended scientific research, management and development approaches, identification of roles and responsibilities, risk management, and definition of project deliverables. The primary focus of the paper will be on the first of the three ground-based human research subprojects, since it is the only one currently in development and is scheduled to start active subject investigations in April of 2005.

Visualizing Without Vision at the Microscale: Students With Visual Impairments Explore Cells With Touch

NASA Astrophysics Data System (ADS)

Jones, M. Gail; Minogue, James; Oppewal, Tom; Cook, Michelle P.; Broadwell, Bethany

2006-12-01

Science instruction is typically highly dependent on visual representations of scientific concepts that are communicated through textbooks, teacher presentations, and computer-based multimedia materials. Little is known about how students with visual impairments access and interpret these types of visually-dependent instructional materials. This study explored the efficacy of new haptic (simulated tactile feedback and kinesthetics) instructional technology for teaching cell morphology and function to middle and high school students with visual impairments. The study examined students' prior experiences learning about the cell and cell functions in classroom instruction, as well as how haptic feedback technology impacted students' awareness of the 3-D nature of an animal cell, the morphology and function of cell organelles, and students' interest in the haptic technology as an instructional tool. Twenty-one students with visual impairment participated in the study. Students explored a tactile model of the cell with a haptic point probe that allowed them to feel the cell and its organelles. Results showed that students made significant gains in their ability to identify cell organelles and found the technology to be highly interesting as an instructional tool. The need for additional adaptive technology for students with visual impairments is discussed.

Detection of Impaired Cerebral Autoregulation Using Selected Correlation Analysis: A Validation Study

PubMed Central

Brawanski, Alexander

2017-01-01

Multimodal brain monitoring has been utilized to optimize treatment of patients with critical neurological diseases. However, the amount of data requires an integrative tool set to unmask pathological events in a timely fashion. Recently we have introduced a mathematical model allowing the simulation of pathophysiological conditions such as reduced intracranial compliance and impaired autoregulation. Utilizing a mathematical tool set called selected correlation analysis (sca), correlation patterns, which indicate impaired autoregulation, can be detected in patient data sets (scp). In this study we compared the results of the sca with the pressure reactivity index (PRx), an established marker for impaired autoregulation. Mean PRx values were significantly higher in time segments identified as scp compared to segments showing no selected correlations (nsc). The sca based approach predicted cerebral autoregulation failure with a sensitivity of 78.8% and a specificity of 62.6%. Autoregulation failure, as detected by the results of both analysis methods, was significantly correlated with poor outcome. Sca of brain monitoring data detects impaired autoregulation with high sensitivity and sufficient specificity. Since the sca approach allows the simultaneous detection of both major pathological conditions, disturbed autoregulation and reduced compliance, it may become a useful analysis tool for brain multimodal monitoring data. PMID:28255331

Detection of Impaired Cerebral Autoregulation Using Selected Correlation Analysis: A Validation Study.

PubMed

Proescholdt, Martin A; Faltermeier, Rupert; Bele, Sylvia; Brawanski, Alexander

2017-01-01

Multimodal brain monitoring has been utilized to optimize treatment of patients with critical neurological diseases. However, the amount of data requires an integrative tool set to unmask pathological events in a timely fashion. Recently we have introduced a mathematical model allowing the simulation of pathophysiological conditions such as reduced intracranial compliance and impaired autoregulation. Utilizing a mathematical tool set called selected correlation analysis (sca), correlation patterns, which indicate impaired autoregulation, can be detected in patient data sets (scp). In this study we compared the results of the sca with the pressure reactivity index (PRx), an established marker for impaired autoregulation. Mean PRx values were significantly higher in time segments identified as scp compared to segments showing no selected correlations (nsc). The sca based approach predicted cerebral autoregulation failure with a sensitivity of 78.8% and a specificity of 62.6%. Autoregulation failure, as detected by the results of both analysis methods, was significantly correlated with poor outcome. Sca of brain monitoring data detects impaired autoregulation with high sensitivity and sufficient specificity. Since the sca approach allows the simultaneous detection of both major pathological conditions, disturbed autoregulation and reduced compliance, it may become a useful analysis tool for brain multimodal monitoring data.

Use of the Hydrological Simulation Program-FORTRAN and bacterial source tracking for development of the fecal coliform total maximum daily load (TMDL) for Christians Creek, Augusta County, Virginia

USGS Publications Warehouse

Moyer, Douglas; Hyer, Kenneth

2003-01-01

Impairment of surface waters by fecal coliform bacteria is a water-quality issue of national scope and importance. Section 303(d) of the Clean Water Act requires that each State identify surface waters that do not meet applicable water-quality standards. In Virginia, more than 175 stream segments are on the 1998 Section 303(d) list of impaired waters because of violations of the water-quality standard for fecal coliform bacteria. A total maximum daily load (TMDL) will need to be developed by 2006 for each of these impaired streams and rivers by the Virginia Departments of Environmental Quality and Conservation and Recreation. A TMDL is a quantitative representation of the maximum load of a given water-quality constituent, from all point and nonpoint sources, that a stream can assimilate without violating the designated water-quality standard. Christians Creek, in Augusta County, Virginia, is one of the stream segments listed by the State of Virginia as impaired by fecal coliform bacteria. Watershed modeling and bacterial source tracking were used to develop the technical components of the fecal coliform bacteria TMDL for Christians Creek. The Hydrological Simulation Program?FORTRAN (HSPF) was used to simulate streamflow, fecal coliform concentrations, and source-specific fecal coliform loading in Christians Creek. Ribotyping, a bacterial source tracking technique, was used to identify the dominant sources of fecal coliform bacteria in the Christians Creek watershed. Ribotyping also was used to determine the relative contributions of specific sources to the observed fecal coliform load in Christians Creek. Data from the ribotyping analysis were incorporated into the calibration of the fecal coliform model. Study results provide information regarding the calibration of the streamflow and fecal coliform bacteria models and also identify the reductions in fecal coliform loads required to meet the TMDL for Christians Creek. The calibrated streamflow model simulated observed streamflow characteristics with respect to total annual runoff, seasonal runoff, average daily streamflow, and hourly stormflow. The calibrated fecal coliform model simulated the patterns and range of observed fecal coliform bacteria concentrations. Observed fecal coliform bacteria concentrations during low-flow periods ranged from 40 to 2,000 colonies per 100 milliliters, and peak concentrations during stormflow periods ranged from 23,000 to 730,000 colonies per 100 milliliters. Additionally, fecal coliform bacteria concentrations were generally higher upstream and lower downstream. Simulated source-specific contributions of fecal coliform bacteria to instream load were matched to the observed contributions from the dominant sources, which were beaver, cats, cattle, deer, dogs, ducks, geese, horses, humans, muskrats, poultry, raccoons, and sheep. According to model results, a 96-percent reduction in the current fecal coliform load delivered from the watershed to Christians Creek would result in compliance with the designated water-quality goals and associated TMDL.

Using alcohol intoxication goggles (Fatal Vision® goggles) to detect alcohol related impairment in simulated driving.

PubMed

McCartney, Danielle; Desbrow, Ben; Irwin, Christopher

2017-01-02

Fatal vision goggles (FVGs) are image-distorting equipment used within driver education programs to simulate alcohol-related impairment. However, there is no empirical evidence comparing the behavioral effects associated with wearing FVGs to alcohol intoxication. The purpose of this study was to determine the validity of FVGs in producing alcohol-related impairment in simulated driving. Twenty-two healthy males (age: 23 ± 3 years, mean ± SD) participated in a placebo-controlled crossover design study involving 4 experimental trials. In each trial, participants completed a baseline level simulated driving task followed by an experimental driving task, involving one of 4 treatments: (1) a dose of alcohol designed to elicit 0.080% breath alcohol concentration (BrAC; AB), (2) an alcohol placebo beverage (PB), (3) FVG (estimated % blood alcohol concentration [BAC] 0.070-0.100+), and (4) placebo goggles (PGs). The driving tasks included 3 separate scenarios lasting ∼5 min each; these were a simple driving scenario, a complex driving scenario, and a hazard perception driving scenario. Selected lateral control parameters (standard deviation of lane position [SDLP]; total number of lane crossings [LCs]) and longitudinal control parameters (average speed; standard deviation of speed [SDSP]; distance headway; minimum distance headway) were monitored during the simple and complex driving scenarios. Latency to 2 different stimuli (choice reaction time [CRT]) was tested in the hazard perception driving scenario. Subjective ratings of mood and attitudes toward driving were also provided during each of the trials. Neither placebo treatment influenced simulated driving performance. Mean BrAC was 0.060 ± 0.010% at the time of driving on the AB trial. Lateral control: In the simple driving scenario, SDLP and LC were not affected under any of the experimental treatments. However, in the complex driving scenario, significantly greater SDLP was observed on both the FVG and AB trials compared to their respective baseline drives. LC increased significantly from baseline on the AB trial only. Longitudinal control: Speed was not affected by any of the experimental treatments; however, SDSP increased significantly from baseline on the FVG trial. A significant reduction in distance headway and minimum distance headway was detected on the FVG trial compared to baseline. Hazard perception: Neither AB nor FVG trials were influential on CRT. Subjective mood ratings were significantly altered on the AB and FVG trials compared to baseline and placebo conditions. Participants reported reduced willingness and ability to drive under the active treatments (AB and FVG) than the placebo treatments (PB and PG). FVGs may have some utility in replicating alcohol-related impairment on specific driving performance measurements. Hence, the equipment may offer an alternative approach to researching the impact of alcohol intoxication on simulated driving performance among populations where the provision of alcohol would otherwise be unethical (e.g., prelicensed drivers).

Physiological stress response, reflex impairment and delayed mortality of white sturgeon Acipenser transmontanus exposed to simulated fisheries stressors

PubMed Central

McLean, Montana F.; Hanson, Kyle C.; Cooke, Steven J.; Hinch, Scott G.; Patterson, David A.; Nettles, Taylor L.; Litvak, Matt K.; Crossin, Glenn T.

2016-01-01

White sturgeon (Acipenser transmontanus) are the largest freshwater fish in North America and a species exposed to widespread fishing pressure. Despite the growing interest in recreational fishing for white sturgeon, little is known about the sublethal and lethal impacts of angling on released sturgeon. In summer (July 2014, mean water temperature 15.3°C) and winter (February 2015, mean water temperature 6.6°C), captive white sturgeon (n = 48) were exposed to a combination of exercise and air exposure as a method of simulating an angling event. After the stressor, sturgeon were assessed for a physiological stress response, and reflex impairments were quantified to determine overall fish vitality (i.e. capacity for survival). A physiological stress response occurred in all sturgeon exposed to a fishing-related stressor, with the magnitude of the response correlated with the duration of the stressor. Moreover, the stress from exercise was more pronounced in summer, leading to higher reflex impairment scores (mean ± SEM, 0.44 ± 0.07 and 0.25 ± 0.05 in summer and winter, respectively). Reflex impairment was also correlated with lactate concentrations (e.g. physiological stress measures related to exhaustive exercise; r = 0.53) and recovery time (r = 0.76). Two mortalities occurred >24 h after the cessation of treatment in the summer. Given that natural habitats for white sturgeon can reach much higher temperatures than those presented in our study, we caution the use of this mortality estimate for a summer season, because latent mortality could be much higher when temperatures exceed 16°C. This is the first experiment investigating the physiological disturbance and reflex impairment of capture and release at two temperatures on subadult/adult white sturgeon, and the results suggest that future research needs to examine the longer term and fitness consequences of extended play and air exposure times, because these are largely unknown for wild populations. PMID:27766153

Simulation of conservation practices using the APEX model

USDA-ARS?s Scientific Manuscript database

Information on agricultural Best Management Practices (BMPs) and their effectiveness in controlling agricultural non-point source pollution is crucial in developing Clean Water Act programs such as the Total Maximum Daily Loads for impaired watersheds. A modeling study was conducted to evaluate var...

Spatial navigation, episodic memory, episodic future thinking, and theory of mind in children with autism spectrum disorder: evidence for impairments in mental simulation?

PubMed Central

Lind, Sophie E.; Bowler, Dermot M.; Raber, Jacob

2014-01-01

This study explored spatial navigation alongside several other cognitive abilities that are thought to share common underlying neurocognitive mechanisms (e.g., the capacity for self-projection, scene construction, or mental simulation), and which we hypothesized may be impaired in autism spectrum disorder (ASD). Twenty intellectually high-functioning children with ASD (with a mean age of ~8 years) were compared to 20 sex, age, IQ, and language ability matched typically developing children on a series of tasks to assess spatial navigation, episodic memory, episodic future thinking (also known as episodic foresight or prospection), theory of mind (ToM), relational memory, and central coherence. This is the first study to explore these abilities concurrently within the same sample. Spatial navigation was assessed using the “memory island” task, which involves finding objects within a realistic, computer simulated, three-dimensional environment. Episodic memory and episodic future thinking were assessed using a past and future event description task. ToM was assessed using the “animations” task, in which children were asked to describe the interactions between two animated triangles. Relational memory was assessed using a recognition task involving memory for items (line drawings), patterned backgrounds, or combinations of items and backgrounds. Central coherence was assessed by exploring differences in performance across segmented and unsegmented versions of block design. Children with ASD were found to show impairments in spatial navigation, episodic memory, episodic future thinking, and central coherence, but not ToM or relational memory. Among children with ASD, spatial navigation was found to be significantly negatively related to the number of repetitive behaviors. In other words, children who showed more repetitive behaviors showed poorer spatial navigation. The theoretical and practical implications of the results are discussed. PMID:25538661

Spatial navigation, episodic memory, episodic future thinking, and theory of mind in children with autism spectrum disorder: evidence for impairments in mental simulation?

PubMed

Lind, Sophie E; Bowler, Dermot M; Raber, Jacob

2014-01-01

This study explored spatial navigation alongside several other cognitive abilities that are thought to share common underlying neurocognitive mechanisms (e.g., the capacity for self-projection, scene construction, or mental simulation), and which we hypothesized may be impaired in autism spectrum disorder (ASD). Twenty intellectually high-functioning children with ASD (with a mean age of ~8 years) were compared to 20 sex, age, IQ, and language ability matched typically developing children on a series of tasks to assess spatial navigation, episodic memory, episodic future thinking (also known as episodic foresight or prospection), theory of mind (ToM), relational memory, and central coherence. This is the first study to explore these abilities concurrently within the same sample. Spatial navigation was assessed using the "memory island" task, which involves finding objects within a realistic, computer simulated, three-dimensional environment. Episodic memory and episodic future thinking were assessed using a past and future event description task. ToM was assessed using the "animations" task, in which children were asked to describe the interactions between two animated triangles. Relational memory was assessed using a recognition task involving memory for items (line drawings), patterned backgrounds, or combinations of items and backgrounds. Central coherence was assessed by exploring differences in performance across segmented and unsegmented versions of block design. Children with ASD were found to show impairments in spatial navigation, episodic memory, episodic future thinking, and central coherence, but not ToM or relational memory. Among children with ASD, spatial navigation was found to be significantly negatively related to the number of repetitive behaviors. In other words, children who showed more repetitive behaviors showed poorer spatial navigation. The theoretical and practical implications of the results are discussed.

The Impact of Distraction on the Driving Performance of Adolescents with and without Attention Deficit Hyperactivity Disorder

PubMed Central

Narad, Megan; Garner, Annie A.; Brassell, Anne A.; Saxby, Dyani; Antonini, Tanya N.; O'Brien, Kathleen M.; Tamm, Leanne; Matthews, Gerald; Epstein, Jeffery N.

2013-01-01

Importance This study extends the literature regarding Attention-Deficit/Hyperactivity Disorder (ADHD) related driving impairments to a newly-licensed, adolescent population. Objective To investigate the combined risks of adolescence, ADHD, and distracted driving (cell phone conversation and text messaging) on driving performance. Design Adolescents with and without ADHD engaged in a simulated drive under three conditions (no distraction, cell phone conversation, texting). During each condition, one unexpected event (e.g., car suddenly merging into driver's lane) was introduced. Setting Driving simulator. Participants Adolescents aged 16–17 with ADHD (n=28) and controls (n=33). Interventions/Main Exposures Cell phone conversation, texting, and no distraction while driving. Outcome Measures Self-report of driving history; Average speed, standard deviation of speed, standard deviation of lateral position, braking reaction time during driving simulation. Results Adolescents with ADHD reported fewer months of driving experience and a higher proportion of driving violations than controls. After controlling for months of driving history, adolescents with ADHD demonstrated more variability in speed and lane position than controls. There were no group differences for braking reaction time. Further, texting negatively impacted the driving performance of all participants as evidenced by increased variability in speed and lane position. Conclusions This study, one of the first to investigate distracted driving in adolescents with ADHD, adds to a growing body of literature documenting that individuals with ADHD are at increased risk for negative driving outcomes. Furthermore, texting significantly impairs the driving performance of all adolescents and increases existing driving-related impairment in adolescents with ADHD, highlighting the need for education and enforcement of regulations against texting for this age group. PMID:23939758

Dissociation between learning and memory impairment and other sickness behaviours during simulated Mycoplasma infection in rats.

PubMed

Swanepoel, Tanya; Harvey, Brian H; Harden, Lois M; Laburn, Helen P; Mitchell, Duncan

2011-11-01

To investigate potential consequences for learning and memory, we have simulated the effects of Mycoplasma infection, in rats, by administering fibroblast-stimulating lipopepide-1 (FSL-1), a pyrogenic moiety of Mycoplasma salivarium. We measured the effects on body temperature, cage activity, food intake, and on spatial learning and memory in a Morris Water Maze. Male Sprague-Dawley rats had radio transponders implanted to measure abdominal temperature and cage activity. After recovery, rats were assigned randomly to receive intraperitoneal (I.P.) injections of FSL-1 (500 or 1000 μg kg(-1) in 1 ml kg(-1) phosphate-buffered saline; PBS) or vehicle (PBS, 1 ml kg(-1)). Body mass and food intake were measured daily. Training in the Maze commenced 18 h after injections and continued daily for four days. Spatial memory was assessed on the fifth day. In other rats, we measured concentrations of brain pro-inflammatory cytokines, interleukin (IL)-1β and IL-6, at 3 and 18 h after injections. FSL-1 administration induced a dose-dependent fever (∼1°C) for two days, lethargy (∼78%) for four days, anorexia (∼65%) for three days and body mass stunting (∼6%) for at least four days. Eighteen hours after FSL-1 administration, when concentrations of IL-1β, but not that of IL-6, were elevated in both the hypothalamus and the hippocampus, and when rats were febrile, lethargic and anorexic, learning in the Maze was unaffected. There also was no memory impairment. Our results support emerging evidence that impaired learning and memory is not inevitable during simulated infection. Copyright © 2011 Elsevier Inc. All rights reserved.

Accessibility assessment of assistive technology for the hearing impaired.

PubMed

Áfio, Aline Cruz Esmeraldo; Carvalho, Aline Tomaz de; Caravalho, Luciana Vieira de; Silva, Andréa Soares Rocha da; Pagliuca, Lorita Marlena Freitag

2016-01-01

to assess the automatic accessibility of assistive technology in online courses for the hearing impaired. evaluation study guided by the Assessment and Maintenance step proposed in the Model of Development of Digital Educational Material. The software Assessor and Simulator for the Accessibility of Sites (ASES) was used to analyze the online course "Education on Sexual and Reproductive Health: the use of condoms" according to the accessibility standards of national and international websites. an error report generated by the program identified, in each didactic module, one error and two warnings related to two international principles and six warnings involved with six national recommendations. The warnings relevant to hearing-impaired people were corrected, and the course was considered accessible by automatic assessment. we concluded that the pages of the course were considered, by the software used, appropriate to the standards of web accessibility.

A robotic voice simulator and the interactive training for hearing-impaired people.

PubMed

Sawada, Hideyuki; Kitani, Mitsuki; Hayashi, Yasumori

2008-01-01

A talking and singing robot which adaptively learns the vocalization skill by means of an auditory feedback learning algorithm is being developed. The robot consists of motor-controlled vocal organs such as vocal cords, a vocal tract and a nasal cavity to generate a natural voice imitating a human vocalization. In this study, the robot is applied to the training system of speech articulation for the hearing-impaired, because the robot is able to reproduce their vocalization and to teach them how it is to be improved to generate clear speech. The paper briefly introduces the mechanical construction of the robot and how it autonomously acquires the vocalization skill in the auditory feedback learning by listening to human speech. Then the training system is described, together with the evaluation of the speech training by auditory impaired people.

Behavioural responses of sardines Sardina pilchardus to simulated purse-seine capture and slipping.

PubMed

Marçalo, A; Araújo, J; Pousão-Ferreira, P; Pierce, G J; Stratoudakis, Y; Erzini, K

2013-09-01

The behavioural effects of confinement of sardine Sardina pilchardus in a purse seine were evaluated through three laboratory experiments simulating the final stages of purse seining; the process of slipping (deliberately allowing fishes to escape) and subsequent exposure to potential predators. Effects of holding time (the time S. pilchardus were held or entangled in the simulation apparatus) and S. pilchardus density were investigated. Experiment 1 compared the effect of a mild fishing stressor (20 min in the net and low S. pilchardus density) with a control (fishing not simulated) while the second and third experiments compared the mild stressor with a severe stressor (40 min in the net and high S. pilchardus density). In all cases, sea bass Dicentrarchus labrax were used as potential predators. Results indicated a significant effect of crowding time and density on the survival and behaviour of slipped S. pilchardus. After simulated fishing, S. pilchardus showed significant behavioural changes including lower swimming speed, closer approaches to predators and higher nearest-neighbour distances (wider school area) than controls, regardless of stressor severity. These results suggest that, in addition to the delayed and unobserved mortality caused by factors related to fishing operations, slipped pelagic fishes can suffer behavioural impairments that may increase vulnerability to predation. Possible sub-lethal effects of behavioural impairment on fitness are discussed, with suggestions on how stock assessment might be modified to account for both unobserved mortality and sub-lethal effects, and possible approaches to provide better estimates of unobserved mortality in the field are provided. © 2013 The Fisheries Society of the British Isles.

Investigating systematic individual differences in sleep-deprived performance on a high-fidelity flight simulator.

PubMed

Van Dongen, Hans P A; Caldwell, John A; Caldwell, J Lynn

2006-05-01

Laboratory research has revealed considerable systematic variability in the degree to which individuals' alertness and performance are affected by sleep deprivation. However, little is known about whether or not different populations exhibit similar levels of individual variability. In the present study, we examined individual variability in performance impairment due to sleep loss in a highly select population of militaryjet pilots. Ten active-duty F-117 pilots were deprived of sleep for 38 h and studied repeatedly in a high-fidelity flight simulator. Data were analyzed with a mixed-model ANOVA to quantify individual variability. Statistically significant, systematic individual differences in the effects of sleep deprivation were observed, even when baseline differences were accounted for. The findings suggest that highly select populations may exhibit individual differences in vulnerability to performance impairment from sleep loss just as the general population does. Thus, the scientific and operational communities' reliance on group data as opposed to individual data may entail substantial misestimation of the impact of job-related stressors on safety and performance.

Rapid Drinking is Associated with Increases in Driving-Related Risk-Taking

PubMed Central

Bernosky-Smith, Kimberly A.; Aston, Elizabeth R.; Liguori, Anthony

2014-01-01

Objective The rate of alcohol drinking has been shown to predict impairment on cognitive and behavioral tasks. The current study assessed the influence of speed of alcohol consumption within a laboratory-administered binge on self-reported attitudes toward driving and simulated driving ability. Method Forty moderate drinkers (20 female, 20 male) were recruited from the local community via advertisements for individuals who drank alcohol at least once per month. The equivalent of four standard alcohol drinks was consumed at the participant’s desired pace within a two-hour session. Results Correlation analyses revealed that, after alcohol drinking, mean simulated driving speed, time in excess of speed limit, collisions, and reported confidence in driving were all associated with rapid alcohol drinking. Conclusion Fast drinking may coincide with increased driving confidence due to the extended latency between the conclusion of drinking and the commencement of driving. However, this latency did not reduce alcohol-related driving impairment, as fast drinking was also associated with risky driving. PMID:23027650

Rapid drinking is associated with increases in driving-related risk-taking.

PubMed

Bernosky-Smith, Kimberly A; Aston, Elizabeth R; Liguori, Anthony

2012-11-01

The rate of alcohol drinking has been shown to predict impairment on cognitive and behavioral tasks. The current study assessed the influence of speed of alcohol consumption within a laboratory-administered binge on self-reported attitudes toward driving and simulated driving ability. Forty moderate drinkers (20 female, 20 male) were recruited from the local community via advertisements for individuals who drank alcohol at least once per month. The equivalent of four standard alcohol drinks was consumed at the participant's desired pace within 2-h session. Correlation analyses revealed that, after alcohol drinking, mean simulated driving speed, time in excess of speed limit, collisions, and reported confidence in driving were all associated with rapid alcohol drinking. Fast drinking may coincide with increased driving confidence because of the extended latency between the conclusion of drinking and the commencement of driving. However, this latency did not reduce alcohol-related driving impairment, as fast drinking was also associated with risky driving. Copyright © 2012 John Wiley & Sons, Ltd.

Mirror Neurons Modeled Through Spike-Timing-Dependent Plasticity are Affected by Channelopathies Associated with Autism Spectrum Disorder.

PubMed

Antunes, Gabriela; Faria da Silva, Samuel F; Simoes de Souza, Fabio M

2018-06-01

Mirror neurons fire action potentials both when the agent performs a certain behavior and watches someone performing a similar action. Here, we present an original mirror neuron model based on the spike-timing-dependent plasticity (STDP) between two morpho-electrical models of neocortical pyramidal neurons. Both neurons fired spontaneously with basal firing rate that follows a Poisson distribution, and the STDP between them was modeled by the triplet algorithm. Our simulation results demonstrated that STDP is sufficient for the rise of mirror neuron function between the pairs of neocortical neurons. This is a proof of concept that pairs of neocortical neurons associating sensory inputs to motor outputs could operate like mirror neurons. In addition, we used the mirror neuron model to investigate whether channelopathies associated with autism spectrum disorder could impair the modeled mirror function. Our simulation results showed that impaired hyperpolarization-activated cationic currents (Ih) affected the mirror function between the pairs of neocortical neurons coupled by STDP.

Perception of premenstrual syndrome and attitude of evaluations of work performance among incoming university female students.

PubMed

Cheng, Shu Hui; Sun, Zih-Jie; Lee, I Hui; Shih, Chi-Chen; Chen, Kao Chin; Lin, Shih-Hsien; Lu, Feng-Hwa; Yang, Yi-Ching; Yang, Yen Kuang

2015-01-01

Premenstrual syndrome (PMS) is a common condition, and for 5% of women, the influence is so severe as to interfere with their mental health, interpersonal relationships, or studies. Severe PMS may result in decreased occupational productivity. The aim of this study was to investigate the influence of perception of PMS on evaluation of work performance. A total of 1971 incoming female university students were recruited in September 2009. A simulated clinical scenario was used, with a test battery including measurement of psychological symptoms and the Chinese Premenstrual Symptom Questionnaire. When evaluating employee performance in the simulated scenario, 1565 (79.4%) students neglected the impact of PMS, while 136 (6.9%) students considered it. Multivariate logistic regression showed that perception of daily function impairment due to PMS and frequency of measuring body weight were significantly associated with consideration of the influence of PMS on evaluation of work performance. It is important to increase the awareness of functional impairments related to severe PMS.

The Influence of Audio-Visual Cueing (Traffic Light) on Dual Task Walking in Healthy Older Adults and Older Adults with Balance Impairments.

PubMed

Kaewkaen, Kitchana; Wongsamud, Phongphat; Ngaothanyaphat, Jiratchaya; Supawarapong, Papawarin; Uthama, Suraphong; Ruengsirarak, Worasak; Chanabun, Suthin; Kaewkaen, Pratchaya

2018-02-01

The walking gait of older adults with balance impairment is affected by dual tasking. Several studies have shown that external cues can stimulate improvement in older adults' performance. There is, however, no current evidence to support the usefulness of external cues, such as audio-visual cueing, in dual task walking in older adults. Thus, the aim of this study was to investigate the influence of an audio-visual cue (simulated traffic light) on dual task walking in healthy older adults and in older adults with balance impairments. A two-way repeated measures study was conducted on 14 healthy older adults and 14 older adults with balance impairment, who were recruited from the community in Chiang Rai, Thailand. Their walking performance was assessed using a four-metre walking test at their preferred gait speed and while walking under two further gait conditions, in randomised order: dual task walking and dual task walking with a simulated traffic light. Each participant was tested individually, with the testing taking between 15 and 20 minutes to perform, including two-minute rest periods between walking conditions. Two Kinect cameras recorded the spatio-temporal parameters using MFU gait analysis software. Each participant was tested for each condition twice. The mean parameters for each condition were analysed using a two-way repeated measures analysis of variance (ANOVA) with participant group and gait condition as factors. There was no significant between-group effect for walking speed, stride length and cadence. There were also no significant effects between gait condition and stride length or cadence. However, the effect between gait condition and walking speed was found to be significant [F(1.557, 40.485) = 4.568, P = 0.024, [Formula: see text

Novice drivers' performance after different alcohol dosages and placebo in the divided-attention steering simulator (DASS).

PubMed

Verster, Joris C; Wester, Anne E; Goorden, Maartje; van Wieringen, Jan-Peter; Olivier, Berend; Volkerts, Edmund R

2009-05-01

The divided-attention steering simulator (DASS) is designed to measure lane-keeping (i.e., a tracking task using a steering wheel) while performing a secondary visual task (responding to digits that appear in the corners of the computer screen). Some studies have already used the DASS, but the magnitude of impairment is difficult to interpret because reference values are lacking. To examine the magnitude of impairment after administration of four different dosages of alcohol and placebo. Thirty-two healthy young adults participated in this randomized, single-blind crossover trial. Subjects received alcohol to gain a blood alcohol concentration (BAC) of 0.02%, 0.05%, 0.08%, and 0.10% or alcohol-placebo. Sixteen subjects performed a 30-min test in DASS (dual-task condition). Outcome measures were steering error, reaction time, and percentage of errors. Sixteen other subjects performed the test without performing the secondary peripheral task (single-task condition). Twenty-eight subjects (novice drivers; drivers' license up to 5 years) were included in the analyses. Dose-dependent impairment was found in both the single-task condition (F ((4,11)) = 10.86, p < 0.001) and the dual-task condition (F ((4,9)) = 5.58, p < 0.015). Performance at all BAC levels differed significantly (p < 0.05) from alcohol-placebo, except BAC 0.02%. With increasing BAC levels, subjects made more errors and reacted slower on the peripheral visual search task, but these effects did not reach significance. With increasing BAC, dose-dependent impairment was found. The DASS seems to be a suitable divided-attention task that is useful in psychopharmacological research and training of novice drivers.

Human factors for the Moon: the gap in anthropometric data.

NASA Astrophysics Data System (ADS)

Lia Schlacht, Irene; Foing, Bernard H.; Rittweger, Joern; Masali, Melchiorre; Stevenin, Hervé

2016-07-01

Since the space era began, we learned first to survive and then to live in space. In the state of the art, we know how important human factors research and development is to guarantee maximum safety and performance for human missions. With the extension of the duration of space missions, we also need to learn how habitability and comfort factors are closely related to safety and performance. Humanities disciplines such as design, architecture, anthropometry, and anthropology are now involved in mission design from the start. Actual plans for building a simulated Moon village in order to simulate and test Moon missions are now being carried out using a holistic approach, involving multidisciplinary experts cooperating concurrently with regard to the interactions among humans, technology, and the environment. However, in order to implement such plans, we need basic anthropometrical data, which is still missing. In other words: to optimize performance, we need to create doors and ceilings with dimensions that support a natural human movement in the reduced gravity environment of the Moon, but we are lacking detailed anthropometrical data on human movement on the Moon. In the Apollo missions more than 50 years ago, no anthropometrical studies were carried in hypogravity out as far as we know. The necessity to collect data is very consistent with state-of-the-art research. We still have little knowledge of how people will interact with the Moon environment. Specifically, it is not known exactly which posture, which kind of walking and running motions astronauts will use both inside and outside a Moon station. Considering recent plans for a Moon mission where humans will spend extensive time in reduced gravity conditions, the need for anthropometric, biomechanics and kinematics field data is a priority in order to be able to design the right architecture, infrastructure, and interfaces. Objective of this paper: Bring knowledge on the relevance of anthropometrical and human factors contribution Present the ongoing research on this field Share innovative methodologies in order to acquire feedback from other specialist. This research is aimed at reconsidering the methodologies from the viewpoint of anthropometry and human system interaction in a different kind of gravity and carry out new investigations that may help to prepare for the next Moon mission, but which can also be used for advanced applications on Earth. Experimental setups and methodologies for achieving anthropometrical data will be described. In particular, combined studies involving bed rest, treadmills, parabolic flight, neutral buoyancy, and weight suspension with cables will be presented. From a spin-off perspective, this research is also extremely promising in terms of basic research aimed at better understanding human physiological mechanisms ruling equilibrium, deambulation, and related topics, which are also useful for applications on Earth.

Safety, Tolerability, and Pharmacokinetics of Ribavirin in Hepatitis C Virus-Infected Patients with Various Degrees of Renal Impairment

PubMed Central

Wang, K.; Blotner, S.; Magnusson, M. O.; Wilkins, J. J.; Martin, P.; Solsky, J.; Nieforth, K.; Wat, C.; Grippo, J. F.

2013-01-01

Ribavirin (RBV) is an integral part of standard-of-care hepatitis C virus (HCV) treatments and many future regimens under investigation. The pharmacokinetics (PK), safety, and tolerability of RBV in chronically HCV-infected patients with renal impairment are not well defined and were the focus of an open-label PK study in HCV-infected patients receiving RBV plus pegylated interferon. Serial RBV plasma samples were collected over 12 h on day 1 of weeks 1 and 12 from patients with moderate renal impairment (creatinine clearance [CLCR], 30 to 50 ml/min; RBV, 600 mg daily), severe renal impairment (CLCR, <30 ml/min; RBV, 400 mg daily), end-stage renal disease (ESRD) (RBV, 200 mg daily), or normal renal function (CLCR, >80 ml/min; RBV, 800 to 1,200 mg daily). Of the 44 patients, 9 had moderately impaired renal function, 10 had severely impaired renal function, 13 had ESRD, and 12 had normal renal function. The RBV dose was reduced because of adverse events (AEs) in 71% and 53% of severe and moderate renal impairment groups, respectively. Despite this modification, patients with moderate and severe impairment had 12-hour (area under the concentration-time curve from 0 to 12 h [AUC0–12]) values 36% (38,452 ng · h/ml) and 25% (35,101 ng · h/ml) higher, respectively, than those with normal renal function (28,192 ng · h/ml). Patients with ESRD tolerated a 200-mg daily dose, and AUC0–12 was 20% lower (22,629 ng · h/ml) than in patients with normal renal function. PK modeling and simulation (M&S) indicated that doses of 200 mg or 400 mg alternating daily for patients with moderate renal impairment and 200 mg daily for patients with severe renal impairment were the most appropriate dose regimens in these patients. PMID:24080649

A Novel Dynamic Physical Layer Impairment-Aware Routing and Wavelength Assignment (PLI-RWA) Algorithm for Mixed Line Rate (MLR) Wavelength Division Multiplexed (WDM) Optical Networks

NASA Astrophysics Data System (ADS)

Iyer, Sridhar

2016-12-01

The ever-increasing global Internet traffic will inevitably lead to a serious upgrade of the current optical networks' capacity. The legacy infrastructure can be enhanced not only by increasing the capacity but also by adopting advance modulation formats, having increased spectral efficiency at higher data rate. In a transparent mixed-line-rate (MLR) optical network, different line rates, on different wavelengths, can coexist on the same fiber. Migration to data rates higher than 10 Gbps requires the implementation of phase modulation schemes. However, the co-existing on-off keying (OOK) channels cause critical physical layer impairments (PLIs) to the phase modulated channels, mainly due to cross-phase modulation (XPM), which in turn limits the network's performance. In order to mitigate this effect, a more sophisticated PLI-Routing and Wavelength Assignment (PLI-RWA) scheme needs to be adopted. In this paper, we investigate the critical impairment for each data rate and the way it affects the quality of transmission (QoT). In view of the aforementioned, we present a novel dynamic PLI-RWA algorithm for MLR optical networks. The proposed algorithm is compared through simulations with the shortest path and minimum hop routing schemes. The simulation results show that performance of the proposed algorithm is better than the existing schemes.

Simulation of action potentials from metabolically impaired cardiac myocytes. Role of ATP-sensitive K+ current.

PubMed

Ferrero, J M; Sáiz, J; Ferrero, J M; Thakor, N V

1996-08-01

The role of the ATP-sensitive K+ current (IK-ATP) and its contribution to electrophysiological changes that occur during metabolic impairment in cardiac ventricular myocytes is still being discussed. The aim of this work was to quantitatively study this issue by using computer modeling. A model of IK-ATP is formulated and incorporated into the Luo-Rudy ionic model of the ventricular action potential. Action potentials under different degrees of activation of IK-ATP are simulated. Our results show that in normal ionic concentrations, only approximately 0.6% of the KATP channels, when open, should account for a 50% reduction in action potential duration. However, increased levels of intracellular Mg2+ counteract this shortening. Under conditions of high [K+]0, such as those found in early ischemia, the activation of only approximately 0.4% of the KATP channels could account for a 50% reduction in action potential duration. Thus, our results suggest that opening of IK-ATP channels should play a significant role in action potential shortening during hypoxic/ischemic episodes, with the fraction of open channels involved being very low ( < 1%). However, the results of the model suggest that activation of IK-ATP alone does not quantitatively account for the observed K+ efflux in metabolically impaired cardiac myocytes. Mechanisms other than KATP channel activation should be responsible for a significant part of the K+ efflux measured in hypoxic/ischemic situations.

Mathematical models in simulation process in rehabilitation of persons with disabilities

NASA Astrophysics Data System (ADS)

Gorie, Nina; Dolga, Valer; Mondoc, Alina

2012-11-01

The problems of people with disability are varied. A disability may be physical, cognitive, mental, sensory, emotional, developmental or some combination of these. The major disabilities which can appear in people's lives are: the blindness, the deafness, the limb-girdle muscular dystrophy, the orthopedic impairment, the visual impairment. A disability is an umbrella term, covering impairments, activity limitations and participation restrictions. A disability may occur during a person's lifetime or may be present from birth. The authors conclude that some of these disabilities like physical, cognitive, mental, sensory, emotional, developmental can be rehabilitated. Starting from this state of affairs the authors present briefly the possibility of using certain mechatronic systems for rehabilitation of persons with different disabilities. The authors focus their presentation on alternative calling the Stewart platform in order to achieve the proposed goal. The authors present a mathematical model of systems theory approach under the parallel system and described its contents can. The authors analyze in a meaningful mathematical model describing the procedure of rehabilitation process. From the affected function biomechanics and taking into account medical recommendations the authors illustrate the mathematical models of rehabilitation work. The authors assemble a whole mathematical model of parallel structure and the rehabilitation process and making simulation and highlighting the results estimated. The authors present in the end work the results envisaged in the end analysis work, conclusions and steps for future work program..

Impaired Upper Esophageal Sphincter Reflexes in Patients with Supra-Esophageal Reflux Disease

PubMed Central

Babaei, Arash; Venu, Mukund; Naini, Sohrab Rahimi; Gonzaga, Jason; Lang, Ivan; Massey, Benson; Jadcherla, Sudarshan; Shaker, Reza

2015-01-01

Background & Aims Normal responses of the upper esophageal sphincter (UES) and esophageal body to liquid reflux events prevent esophagopharyngeal reflux and its complications, but abnormal responses have not been characterized. We investigated whether patients with supra-esophageal reflux disease (SERD) have impaired UES and esophageal body responses to simulated reflux events. Methods We performed a prospective study of 25 patients with SERD (19–82 y old, 13 female) and complaints of regurgitation and supra-esophageal manifestations of reflux. We also included 10 patients with gastroesophageal reflux disease (GERD; 32–60 y old, 7 female) without troublesome regurgitation and supra-esophageal symptoms and 24 healthy asymptomatic individuals (controls; 19–49 y old, 13 female). UES and esophageal body pressure responses, along with luminal distribution of infusate during esophageal rapid and slow infusion of air or liquid, were monitored by concurrent high-resolution manometry and intraluminal impedance. Results A significantly smaller proportion of patients with SERD had UES contractile reflexes in response to slow esophageal infusion of acid than controls or patients with GERD. Only patients with SERD had abnormal UES relaxation responses to rapid distension with saline. Diminished esophageal peristaltic contractions resulted in esophageal stasis in patients with GERD or SERD. Conclusions Patients with SERD and complaints of regurgitation have impaired UES and esophageal responses to simulated liquid reflux events. These patterns could predispose them to esophagopharyngeal reflux. PMID:26188682

Impact of examinees' stereopsis and near visual acuity on laparoscopic virtual reality performance.

PubMed

Hoffmann, Henry; Ruiz-Schirinzi, Rebecca; Goldblum, David; Dell-Kuster, Salome; Oertli, Daniel; Hahnloser, Dieter; Rosenthal, Rachel

2015-10-01

Laparoscopic surgery represents specific challenges, such as the reduction of a three-dimensional anatomic environment to two dimensions. The aim of this study was to investigate the impact of the loss of the third dimension on laparoscopic virtual reality (VR) performance. We compared a group of examinees with impaired stereopsis (group 1, n = 28) to a group with accurate stereopsis (group 2, n = 29). The primary outcome was the difference between the mean total score (MTS) of all tasks taken together and the performance in task 3 (eye-hand coordination), which was a priori considered to be the most dependent on intact stereopsis. The MTS and performance in task 3 tended to be slightly, but not significantly, better in group 2 than in group 1 [MTS: -0.12 (95 % CI -0.32, 0.08; p = 0.234); task 3: -0.09 (95 % CI -0.29, 0.11; p = 0.385)]. The difference of MTS between simulated impaired stereopsis between group 2 (by attaching an eye patch on the adominant eye in the 2nd run) and the first run of group 1 was not significant (MTS: p = 0.981; task 3: p = 0.527). We were unable to demonstrate an impact of impaired examinees' stereopsis on laparoscopic VR performance. Individuals with accurate stereopsis seem to be able to compensate for the loss of the third dimension in laparoscopic VR simulations.

Contextual cueing impairment in patients with age-related macular degeneration.

PubMed

Geringswald, Franziska; Herbik, Anne; Hoffmann, Michael B; Pollmann, Stefan

2013-09-12

Visual attention can be guided by past experience of regularities in our visual environment. In the contextual cueing paradigm, incidental learning of repeated distractor configurations speeds up search times compared to random search arrays. Concomitantly, fewer fixations and more direct scan paths indicate more efficient visual exploration in repeated search arrays. In previous work, we found that simulating a central scotoma in healthy observers eliminated this search facilitation. Here, we investigated contextual cueing in patients with age-related macular degeneration (AMD) who suffer from impaired foveal vision. AMD patients performed visual search using only their more severely impaired eye (n = 13) as well as under binocular viewing (n = 16). Normal-sighted controls developed a significant contextual cueing effect. In comparison, patients showed only a small nonsignificant advantage for repeated displays when searching with their worse eye. When searching binocularly, they profited from contextual cues, but still less than controls. Number of fixations and scan pattern ratios showed a comparable pattern as search times. Moreover, contextual cueing was significantly correlated with acuity in monocular search. Thus, foveal vision loss may lead to impaired guidance of attention by contextual memory cues.

Behavioral consequences of radiation exposure to simulated space radiation in the C57BL/6 mouse: open field, rotorod, and acoustic startle

NASA Technical Reports Server (NTRS)

Pecaut, Michael J.; Haerich, Paul; Zuccarelli, Cara N.; Smith, Anna L.; Zendejas, Eric D.; Nelson, Gregory A.

2002-01-01

Two experiments were carried out to investigate the consequences of exposure to proton radiation, such as might occur for astronauts during space flight. C57BL/6 mice were exposed, either with or without 15-g/cm2 aluminum shielding, to 0-, 3-, or 4-Gy proton irradiation mimicking features of a solar particle event. Irradiation produced transient direct deficits in open-field exploratory behavior and acoustic startle habituation. Rotorod performance at 18 rpm was impaired by exposure to proton radiation and was impaired at 26 rpm, but only for mice irradiated with shielding and at the 4-Gy dose. Long-term (>2 weeks) indirect deficits in open-field activity appeared as a result of impaired experiential encoding immediately following exposure. A 2-week recovery prior to testing decreased most of the direct effects of exposure, with only rotorod performance at 26 rpm being impaired. These results suggest that the performance deficits may have been mediated by radiation damage to hippocampal, cerebellar, and possibly, forebrain dopaminergic function.

Blunt forehead trauma and optic canal involvement: finite element analysis of anterior skull base and orbit on causes of vision impairment.

PubMed

Huempfner-Hierl, Heike; Bohne, Alexander; Wollny, Gert; Sterker, Ina; Hierl, Thomas

2015-10-01

Clinical studies report on vision impairment after blunt frontal head trauma. A possible cause is damage to the optic nerve bundle within the optic canal due to microfractures of the anterior skull base leading to indirect traumatic optic neuropathy. A finite element study simulating impact forces on the paramedian forehead in different grades was initiated. The set-up consisted of a high-resolution skull model with about 740 000 elements, a blunt impactor and was solved in a transient time-dependent simulation. Individual bone material parameters were calculated for each volume element to increase realism. Results showed stress propagation from the frontal impact towards the optic foramen and the chiasm even at low-force fist-like impacts. Higher impacts produced stress patterns corresponding to typical fracture patterns of the anterior skull base including the optic canal. Transient simulation discerned two stress peaks equalling oscillation. It can be concluded that even comparatively low stresses and oscillation in the optic foramen may cause micro damage undiscerned by CT or MRI explaining consecutive vision loss. Higher impacts lead to typical comminuted fractures, which may affect the integrity of the optic canal. Finite element simulation can be effectively used in studying head trauma and its clinical consequences. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Molecular dynamics simulations of Hsp40 J-domain mutants identifies disruption of the critical HPD-motif as the key factor for impaired curing in vivo of the yeast prion [URE3].

PubMed

Xue, You-Lin; Wang, Hao; Riedy, Michael; Roberts, Brittany-Lee; Sun, Yuna; Song, Yong-Bo; Jones, Gary W; Masison, Daniel C; Song, Youtao

2018-05-01

Genetic screens using Saccharomyces cerevisiae have identified an array of Hsp40 (Ydj1p) J-domain mutants that are impaired in the ability to cure the yeast [URE3] prion through disrupting functional interactions with Hsp70. However, biochemical analysis of some of these Hsp40 J-domain mutants has so far failed to provide major insight into the specific functional changes in Hsp40-Hsp70 interactions. To explore the detailed structural and dynamic properties of the Hsp40 J-domain, 20 ns molecular dynamic simulations of 4 mutants (D9A, D36A, A30T, and F45S) and wild-type J-domain were performed, followed by Hsp70 docking simulations. Results demonstrated that although the Hsp70 interaction mechanism of the mutants may vary, the major structural change was targeted to the critical HPD motif of the J-domain. Our computational analysis fits well with previous yeast genetics studies regarding highlighting the importance of J-domain function in prion propagation. During the molecular dynamics simulations several important residues were identified and predicted to play an essential role in J-domain structure. Among these residues, Y26 and F45 were confirmed, using both in silico and in vivo methods, as being critical for Ydj1p function.

Investigating driving behaviour of older drivers with mild cognitive impairment using a portable driving simulator.

PubMed

Devlin, Anna; McGillivray, Jane; Charlton, Judith; Lowndes, Georgia; Etienne, Virginie

2012-11-01

While there is a large body of research indicating that individuals with moderate to severe dementia are unfit to drive, relatively little is known about the driving performance of older drivers with mild cognitive impairment (MCI). The aim of the current study was to examine the driving performance of older drivers with MCI on approach to intersections, and to investigate how their healthy counterparts perform on the same driving tasks using a portable driving simulator. Fourteen drivers with MCI and 14 age-matched healthy older drivers (aged 65-87 years) completed a 10-min simulator drive in an urban environment. The simulator drive consisted of stop-sign controlled and signal-controlled intersections. Drivers were required to stop at the stop-sign controlled intersections and to decide whether or not to proceed through a critical light change at the signal-controlled intersections. The specific performance measures included; approach speed, number of brake applications on approach to the intersection (either excessive or minimal), failure to comply with stop signs, and slower braking response times on approach to a critical light change. MCI patients in our sample performed more poorly than controls across a number of variables. However, because the trends failed to reach statistical significance it will be important to replicate the study using a larger sample to qualify whether the results can be generalised to the broader population. Copyright © 2012 Elsevier Ltd. All rights reserved.

Relative phase noise induced impairment in CO-OFDM optical communication system with distributed fiber Raman amplifier.

PubMed

Wu, Jiadi; Cheng, Jingchi; Tang, Ming; Deng, Lei; Songnian, Fu; Shum, Perry Ping; Liu, Deming

2014-05-15

In this Letter, we demonstrate that the interplay between Raman pump relative intensity noise and cross-phase modulation leads to a relative phase noise (RPN) that brings non-negligible performance degradation to coherent optical orthogonal frequency-division multiplexing (CO-OFDM) transmission systems with co-pumped Raman amplification. By theoretical analysis and numerical simulation, we proved that RPN brings more system impairment in terms of Q-factor penalty than the single carrier system, and relatively larger walk-off between pump and signal helps to suppress the RPN induced impairment. A higher-order modulated signal is less tolerant to RPN than a lower-order signal. With the same spectral efficiency, the quadrature-amplitude modulation format shows better tolerance to RPN than phase-shift keying. The reported findings will be useful for the design and optimization of Raman amplified CO-OFDM multi-carrier transmission systems.

Energy-Efficient Routing and Spectrum Assignment Algorithm with Physical-Layer Impairments Constraint in Flexible Optical Networks

NASA Astrophysics Data System (ADS)

Zhao, Jijun; Zhang, Nawa; Ren, Danping; Hu, Jinhua

2017-12-01

The recently proposed flexible optical network can provide more efficient accommodation of multiple data rates than the current wavelength-routed optical networks. Meanwhile, the energy efficiency has also been a hot topic because of the serious energy consumption problem. In this paper, the energy efficiency problem of flexible optical networks with physical-layer impairments constraint is studied. We propose a combined impairment-aware and energy-efficient routing and spectrum assignment (RSA) algorithm based on the link availability, in which the impact of power consumption minimization on signal quality is considered. By applying the proposed algorithm, the connection requests are established on a subset of network topology, reducing the number of transitions from sleep to active state. The simulation results demonstrate that our proposed algorithm can improve the energy efficiency and spectrum resources utilization with the acceptable blocking probability and average delay.

Improving and analyzing signage within a healthcare setting.

PubMed

Rousek, J B; Hallbeck, M S

2011-11-01

Healthcare facilities are increasingly utilizing pictograms rather than text signs to help direct people. The purpose of this study was to analyze a wide variety of standardized healthcare pictograms and the effects of color contrasts and complexity for participants with both normal and impaired vision. Fifty (25 males, 25 females) participants completed a signage recognition questionnaire and identified pictograms while wearing vision simulators to represent specific visual impairment. The study showed that certain color contrasts, complexities and orientations can help or hinder comprehension of signage for people with and without visual impairment. High contrast signage with consistent pictograms involving human figures (not too detailed or too abstract) is most identifiable. Standardization of healthcare signage is recommended to speed up and aid the cognitive thought process in detecting signage and determining meaning. These fundamental signage principles are critical in producing an efficient, universal wayfinding system for healthcare facilities. Copyright © 2011 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Evaluation of impairment of the upper extremity.

PubMed

Blair, S J; McCormick, E; Bear-Lehman, J; Fess, E E; Rader, E

1987-08-01

Evaluation of impairment of the upper extremity is the product of a team effort by the physician, occupational therapist, physical therapist, and rehabilitation counselor. A careful recording of the anatomic impairment should be made because this is critical in determining the subsequent functional activities of the extremity. The measurement criteria for clinical and functional evaluation includes condition assessment instruments. Some assess the neurovascular system, others assess movements including the monitoring of articular motion and musculotendinous function. Sensibility assessment instruments measure sympathetic response and detect single joint stimulus, discrimination, quantification, and recognition abilities. A detailed description of each assessment is recorded and physical capacity evaluation is only one component of the entire vocational evaluation. This evaluation answers questions regarding the injured worker's ability to return to his previous job. The work simulator is a useful instrument that allows rehabilitation and testing of the injured upper extremity. Job site evaluation includes assessment criteria for work performance, work behavior, and work environment.

Effects of optical layer impairments on 2.5 Gb/s optical CDMA transmission.

PubMed

Feng, H; Mendez, A; Heritage, J; Lennon, W

2000-07-03

We conducted a computer simulation study to assess the effects of optical layer impairments on optical CDMA (O-CDMA) transmission of 8 asynchronous users at 2.5 Gb/s each user over a 214-km link. It was found that with group velocity dispersion compensation, two other residual effects, namely, the nonzero chromatic dispersion slope of the single mode fiber (which causes skew) and the non-uniform EDFA gain (which causes interference power level to exceed signal power level of some codes) degrade the signal to multi-access interference (MAI) ratio. In contrast, four wave mixing and modulation due to the Kerr and Raman contributions to the fiber nonlinear refractive index are less important. Current wavelength-division multiplexing (WDM) technologies, including dispersion management, EDFA gain flattening, and 3 rd order dispersion compensation, are sufficient to overcome the impairments to the O-CDMA transmission system that we considered.

No Escaping the Rat Race: Simulated Night Shift Work Alters the Time-of-Day Variation in BMAL1 Translational Activity in the Prefrontal Cortex.

PubMed

Marti, Andrea R; Patil, Sudarshan; Mrdalj, Jelena; Meerlo, Peter; Skrede, Silje; Pallesen, Ståle; Pedersen, Torhild T; Bramham, Clive R; Grønli, Janne

2017-01-01

Millions of people worldwide work during the night, resulting in disturbed circadian rhythms and sleep loss. This may cause deficits in cognitive functions, impaired alertness and increased risk of errors and accidents. Disturbed circadian rhythmicity resulting from night shift work could impair brain function and cognition through disrupted synthesis of proteins involved in synaptic plasticity and neuronal function. Recently, the circadian transcription factor brain-and-muscle arnt-like protein 1 (BMAL1) has been identified as a promoter of mRNA translation initiation, the most highly regulated step in protein synthesis, through binding to the mRNA "cap". In this study we investigated the effects of simulated shift work on protein synthesis markers. Male rats ( n = 40) were exposed to forced activity, either in their rest phase (simulated night shift work) or in their active phase (simulated day shift work) for 3 days. Following the third work shift, experimental animals and time-matched undisturbed controls were euthanized (rest work at ZT12; active work at ZT0). Tissue lysates from two brain regions (prefrontal cortex, PFC and hippocampus) implicated in cognition and sleep loss, were analyzed with m 7 GTP (cap) pull-down to examine time-of-day variation and effects of simulated shift work on cap-bound protein translation. The results show time-of-day variation of protein synthesis markers in PFC, with increased protein synthesis at ZT12. In the hippocampus there was little difference between ZT0 and ZT12. Active phase work did not induce statistically significant changes in protein synthesis markers at ZT0 compared to time-matched undisturbed controls. Rest work, however, resulted in distinct brain-region specific changes of protein synthesis markers compared to time-matched controls at ZT12. While no changes were observed in the hippocampus, phosphorylation of cap-bound BMAL1 and its regulator S6 kinase beta-1 (S6K1) was significantly reduced in the PFC, together with significant reduction in the synaptic plasticity associated protein activity-regulatedcytoskeleton-associated protein (Arc). Our results indicate considerable time-of-day and brain-region specific variation in cap-dependent translation initiation. We concludethat simulated night shift work in rats disrupts the pathways regulating the circadian component of the translation of mRNA in the PFC, and that this may partly explain impaired waking function during night shift work.

Design of an indoor self-positioning system for the visually impaired--simulation with RFID and Bluetooth in a visible light communication system.

PubMed

Liu, Xiaohan; Makino, Hideo; Kobayashi, Suguru; Maeda, Yoshinobu

2007-01-01

After a public experiment of the indoor guidance system using FLC (fluorescent light communication), we found that FLC provides a promising medium for the installation of a guidance system for the visually impaired. However, precise self-positioning was not satisfactorily achieved. In this article, we propose a new self-positioning method, one that uses a combination of RFID (Radio-frequency identification), Bluetooth and FLC. We analyzed the situation and developed a model that combined the three communication modes. Then we performed a series of experiments and get some results in the first step.

Statistical performance evaluation of ECG transmission using wireless networks.

PubMed

Shakhatreh, Walid; Gharaibeh, Khaled; Al-Zaben, Awad

2013-07-01

This paper presents simulation of the transmission of biomedical signals (using ECG signal as an example) over wireless networks. Investigation of the effect of channel impairments including SNR, pathloss exponent, path delay and network impairments such as packet loss probability; on the diagnosability of the received ECG signal are presented. The ECG signal is transmitted through a wireless network system composed of two communication protocols; an 802.15.4- ZigBee protocol and an 802.11b protocol. The performance of the transmission is evaluated using higher order statistics parameters such as kurtosis and Negative Entropy in addition to the common techniques such as the PRD, RMS and Cross Correlation.

APPLICATION OF ELASTICITY ANALYSES AND PERTURBATION SIMULATIONS IN DETERMINING STRESSOR IMPACTS ON POPULATION GROWTH RATE AND EXTINCTION RISK

EPA Science Inventory

Population structure and life history strategies are determinants of how populations respond to stressor-induced impairments in individual-level responses, but a consistent and holistic analysis has not been reported. Effects on population growth rate were modeled using five theo...

APPLICATION OF PERTURBATION SIMULATIONS IN POPULATION RISK ASSESSMENT FOR DIFFERENT LIFE HISTORY STRATEGIES AND ELASTICITY PATTERNS

EPA Science Inventory

Population structure and life history strategies are determinants of how populations respond to stressor-induced impairments in organism-level responses, but a consistent and holistic analysis has not been reported. Effects on population growth rate were modeled using seven theor...

Measuring Executive Function Deficits Following Head Injury: An Application of SMS Simulation Technology

ERIC Educational Resources Information Center

Satish, Usha; Streufert, Siegfried; Eslinger, Paul J.

2006-01-01

Neuropsychological tests have limited sensitivity in identifying subtle residual cognitive impairments in patients with good medical recovery from head injury and post-concussive syndrome. Detecting and characterizing residual "real life" cognitive difficulties can be problematic for treatment purposes. This study investigated the usefulness of a…

It's not just what you eat but when: The impact of eating a meal during simulated shift work on driving performance.

PubMed

Gupta, Charlotte C; Dorrian, Jill; Grant, Crystal L; Pajcin, Maja; Coates, Alison M; Kennaway, David J; Wittert, Gary A; Heilbronn, Leonie K; Della Vedova, Chris B; Banks, Siobhan

2017-01-01

Shiftworkers have impaired performance when driving at night and they also alter their eating patterns during nightshifts. However, it is unknown whether driving at night is influenced by the timing of eating. This study aims to explore the effects of timing of eating on simulated driving performance across four simulated nightshifts. Healthy, non-shiftworking males aged 18-35 years (n = 10) were allocated to either an eating at night (n = 5) or no eating at night (n = 5) condition. During the simulated nightshifts at 1730, 2030 and 0300 h, participants performed a 40-min driving simulation, 3-min Psychomotor Vigilance Task (PVT-B), and recorded their ratings of sleepiness on a subjective scale. Participants had a 6-h sleep opportunity during the day (1000-1600 h). Total 24-h food intake was consistent across groups; however, those in the eating at night condition ate a large meal (30% of 24-h intake) during the nightshift at 0130 h. It was found that participants in both conditions experienced increased sleepiness and PVT-B impairments at 0300 h compared to 1730 and 2030 h (p < 0.001). Further, at 0300 h, those in the eating condition displayed a significant decrease in time spent in the safe zone (p < 0.05; percentage of time within 10 km/h of the speed limit and 0.8 m of the centre of the lane) and significant increases in speed variability (p < 0.001), subjective sleepiness (p < 0.01) and number of crashes (p < 0.01) compared to those in the no eating condition. Results suggest that, for optimal performance, shiftworkers should consider restricting food intake during the night.

Acute effects of alcohol on inhibitory control and simulated driving in DUI offenders.

PubMed

Van Dyke, Nicholas; Fillmore, Mark T

2014-06-01

The public health costs associated with alcohol-related traffic accidents have prompted considerable research aimed at identifying characteristics of individuals who drive under the influence (DUI) in order to improve treatment and prevention strategies. Survey studies consistently show that DUI offenders self-report higher levels of impulsivity compared to their nonoffending counterparts. However, little is known about how individuals with a DUI history respond under alcohol. Inhibitory control is a behavioral component of impulsivity thought to underlie risky drinking and driving behaviors. The present study examined the degree to which DUI drivers display deficits of inhibitory control in response to alcohol and the degree to which alcohol impaired their simulated driving performance. It was hypothesized that DUI offenders would display an increased sensitivity to the acute impairing effects of alcohol on simulated driving performance. Young adult drivers with a history of DUI and a demographically-comparable group of drivers with no history of DUI (controls) were tested following a 0.65 g/kg dose of alcohol and a placebo. Inhibitory control was measured by using a cued go/no-go task. Drivers then completed a driving simulation task that yielded multiple indicators of driving performance, such as within-lane deviation, steering rate, centerline crossings and road edge excursions, and drive speed. Results showed that although DUI offenders self-reported greater levels of impulsivity than did controls, no group differences were observed in the degree to which alcohol impaired inhibitory control and driving performance. The findings point to the need to identify other aspects of behavioral dysfunction underlying the self-reported impulsivity among DUI offenders, and to better understand the specific driving situations that might pose greater risk to DUI offenders. The systematic study of candidate cognitive deficits in DUI offenders will provide important information on their role in risky driving behavior and decisions to drink and drive. Such information is critical for guiding new interventions for DUI offenders that will move treatment beyond general addiction counseling. Copyright © 2014 Elsevier B.V. All rights reserved.

Mild Normobaric Hypoxia Exposure for Human-Autonomy System Testing

NASA Technical Reports Server (NTRS)

Stephens, Chad L.; Kennedy, Kellie D.; Crook, Brenda L.; Williams, Ralph A.; Schutte, Paul

2017-01-01

An experiment investigated the impact of normobaric hypoxia induction on aircraft pilot performance to specifically evaluate the use of hypoxia as a method to induce mild cognitive impairment to explore human-autonomous systems integration opportunities. Results of this exploratory study show that the effect of 15,000 feet simulated altitude did not induce cognitive deficits as indicated by performance on written, computer-based, or simulated flight tasks. However, the subjective data demonstrated increased effort by the human test subject pilots to maintain equivalent performance in a flight simulation task. This study represents current research intended to add to the current knowledge of performance decrement and pilot workload assessment to improve automation support and increase aviation safety.

Bacillus subtilis spore survival and expression of germination-induced bioluminescence after prolonged incubation under simulated Mars atmospheric pressure and composition: implications for planetary protection and lithopanspermia

NASA Technical Reports Server (NTRS)

Nicholson, Wayne L.; Schuerger, Andrew C.

2005-01-01

Bacterial endospores in the genus Bacillus are considered good models for studying interplanetary transfer of microbes by natural or human processes. Although spore survival during transfer itself has been the subject of considerable study, the fate of spores in extraterrestrial environments has received less attention. In this report we subjected spores of a strain of Bacillus subtilis, containing luciferase resulting from expression of an sspB-luxAB gene fusion, to simulated martian atmospheric pressure (7-18 mbar) and composition (100% CO(2)) for up to 19 days in a Mars simulation chamber. We report here that survival was similar between spores exposed to Earth conditions and spores exposed up to 19 days to simulated martian conditions. However, germination-induced bioluminescence was lower in spores exposed to simulated martian atmosphere, which suggests sublethal impairment of some endogenous spore germination processes.

Advanced Life Support Food Subsystem Salad Crop Requirements

NASA Technical Reports Server (NTRS)

Perchonok, Michele H.; Stevens, Irene; Swango, Beverly E.; Toerne, Mary E.; Lane, Helen W. (Technical Monitor)

2002-01-01

As the National Aeronautics and Space Administration (NASA) begins to look towards longer duration space flights, the importance of fresh foods and varied menu choices increases. Long duration space missions require development of both a Transit Food System and a Lunar or Planetary Food System. These two systems are intrinsically different since the first one will be utilized in the transit vehicle in microgravity conditions while the second will be used in conditions of partial gravity (hypogravity). The Transit Food System will consist of prepackaged food of extended shelf life. Microgravity imposes significant limitations on the ability of the crew to handle food and allows only for minimal processing. Salad crops will be available for the planetary mission. Supplementing the transit food system with salad crops is also being considered. These crops will include carrots, tomatoes, lettuce, radish, spinach, chard, cabbage, and onion. The crops will be incorporated in the menu along with the prepackaged food. The fresh tasting salad crops will provide variety, texture, and color in the menu. This variety should provide increased psychological benefit. Preliminary studies on spinach, tomatoes, and bok choy have been completed. Sensory and analytical tests, including color and moisture were conducted on the chamber grown crops and compared to store bought spinach, tomatoes, and bok choy. Preliminary studies of the appropriate serving sizes and number of servings per week have also been conducted.

The US/USSR Biological Satellite Program: COSMOS 936 Mission Overview

NASA Technical Reports Server (NTRS)

Souza, K. A.

1978-01-01

On August 3, 1977, the Soviet Union launched Cosmos 936, an unmanned spacecraft carrying biology and physics experiments from 9 countries, including both the Soviet Union and U.S. The launch marked the second time the Soviet Union has flown U.S. experiments aboard one of its spacecraft, the first being Cosmos 782 launched Nov. 25, 1975, which remained in orbit 19.5 days. Aboard Cosmos 936 were: 30 young male Wistar SPF rats, 20 of which was exposed to hypogravity during flight while the remainder were subjected to a l x g acceleration by continuous configuration; 2) experiments with plants and fruit flies; 3) radiation physics experiments; and 4) a heat convection experiment. After 18.5 days in orbit, the spacecraft landed in central Asia where a Soviet recovery team began experiment operations, including animal autopsies, within 4.5 hr of landing. Half of the animals were autopsied at the recovery site and the remainder returned to Moscow and allowed to readapt to terrestrial gravity for 25 days after which they, too, were autopsied. Specimens for U.S. were initially prepared at the recovery site or Soviet laboratories and transferred to U.S. laboratories for complete analyses. An overview of the mission focusing on preflight, on-orbit, and postflight activities pertinent to the seven U.S. experiments aboard Cosmos 936 will be presented.

Advanced Life Support Project Plan

NASA Technical Reports Server (NTRS)

2002-01-01

Life support systems are an enabling technology and have become integral to the success of living and working in space. As NASA embarks on human exploration and development of space to open the space frontier by exploring, using and enabling the development of space and to expand the human experience into the far reaches of space, it becomes imperative, for considerations of safety, cost, and crew health, to minimize consumables and increase the autonomy of the life support system. Utilizing advanced life support technologies increases this autonomy by reducing mass, power, and volume necessary for human support, thus permitting larger payload allocations for science and exploration. Two basic classes of life support systems must be developed, those directed toward applications on transportation/habitation vehicles (e.g., Space Shuttle, International Space Station (ISS), next generation launch vehicles, crew-tended stations/observatories, planetary transit spacecraft, etc.) and those directed toward applications on the planetary surfaces (e.g., lunar or Martian landing spacecraft, planetary habitats and facilities, etc.). In general, it can be viewed as those systems compatible with microgravity and those compatible with hypogravity environments. Part B of the Appendix defines the technology development 'Roadmap' to be followed in providing the necessary systems for these missions. The purpose of this Project Plan is to define the Project objectives, Project-level requirements, the management organizations responsible for the Project throughout its life cycle, and Project-level resources, schedules and controls.

Report on ESA Topical Team on the Large Radius Human Centrifuge: "The Human Hypergravity Habitat; H3"

NASA Astrophysics Data System (ADS)

van Loon, Jack J. W. A.; Bücker, N.; Berte, J.; Bok, K.; Bos, J.; Boyle, R.; Bravenoer, N.; Chouker, A.; Clement, G.; Cras, P.; Denise, D.; Eekhoff, M.; Felsenberg, D.; Fong, K.; Fuller, C.; Groen, E.; Heer, M.; Hinghofer-Szalkay, H.; Iwase, S.; Karemaker, J. M.; Linnarsson, D.; Lüthen, C.; Narici, M.; Norsk, P.; Paloski, W.; Rutten, M.; Saggini, R.; Stephan, A.; Ullrich, O.; Vautmans, V.; Wuyts, F.; Young, L.

Over the last decades a significant amount of knowledge has been accumulated on the adap-tation of the human body going into near weightless conditions and on its re-adaptation to 1g Earth conditions after space flight. Ground-based paradigms for microgravity simulation have been developed such as head down tilted bed rest and dry-immersion. In such systems the adaptations to long term immobilization and to head-ward fluid shifts have been studied. Questions we address here are: can long-term ground-based centrifugation help us to under-stand and even predict the adaptations to long-term increased gravity conditions? How does the body adapt to chronic (days, weeks or longer) exposure to a hypergravity environment? And, once the body has fully adapted to a hypergravity environment, how does it re-adapt going from a hypergravity state back to a relatively hypo-gravity condition of 1g, or even going from a centrifuge / hypergravity environment into a bed-rest setting? Can such transitions in well-controlled studies bring us closer to understanding the consequences of gravity transitions that the crews will likely experience going to the Moon or to Mars. Is hypergravity a good model to study the effect of re-entry in gravitational environments after long duration space flight? In an ESA -supported Topical Team we address all organ systems known so far to change directly or indirectly by altered gravity conditions. We will identify to which gravity levels the human body can be exposed for longer periods of time and what protocols could be applied to address the questions at hand. We also identify the technology required to ac-complish such long duration hypergravity and re-adaptation studies. Issues like ethics, safety and required logistics should be addressed. As there is limited experience with exposure of hu-man test subjects to prolonged periods of moderately increased g-forces, unexpected harm may occur. Therefore, the information, disclosure and informed consent procedures need special attention. The final outcome of the Topical Team will be a clear answer about the feasibility of the use of hypergravity as a tool and analogue for space research, and if and how hypergravity studies can provide useful knowledge to support future space flight on the one hand and current medical issues in the ageing population (osteoporosis, cardiovascular diseases, obesity) on the other hand.

A Role for the Left Angular Gyrus in Episodic Simulation and Memory.

PubMed

Thakral, Preston P; Madore, Kevin P; Schacter, Daniel L

2017-08-23

Functional magnetic resonance imaging (fMRI) studies indicate that episodic simulation (i.e., imagining specific future experiences) and episodic memory (i.e., remembering specific past experiences) are associated with enhanced activity in a common set of neural regions referred to as the core network. This network comprises the hippocampus, medial prefrontal cortex, and left angular gyrus, among other regions. Because fMRI data are correlational, it is unknown whether activity increases in core network regions are critical for episodic simulation and episodic memory. In the current study, we used MRI-guided transcranial magnetic stimulation (TMS) to assess whether temporary disruption of the left angular gyrus would impair both episodic simulation and memory (16 participants, 10 females). Relative to TMS to a control site (vertex), disruption of the left angular gyrus significantly reduced the number of internal (i.e., episodic) details produced during the simulation and memory tasks, with a concomitant increase in external detail production (i.e., semantic, repetitive, or off-topic information), reflected by a significant detail by TMS site interaction. Difficulty in the simulation and memory tasks also increased after TMS to the left angular gyrus relative to the vertex. In contrast, performance in a nonepisodic control task did not differ statistically as a function of TMS site (i.e., number of free associates produced or difficulty in performing the free associate task). Together, these results are the first to demonstrate that the left angular gyrus is critical for both episodic simulation and episodic memory. SIGNIFICANCE STATEMENT Humans have the ability to imagine future episodes (i.e., episodic simulation) and remember episodes from the past (i.e., episodic memory). A wealth of neuroimaging studies have revealed that these abilities are associated with enhanced activity in a core network of neural regions, including the hippocampus, medial prefrontal cortex, and left angular gyrus. However, neuroimaging data are correlational and do not tell us whether core regions support critical processes for simulation and memory. In the current study, we used transcranial magnetic stimulation and demonstrated that temporary disruption of the left angular gyrus leads to impairments in simulation and memory. The present study provides the first causal evidence to indicate that this region is critical for these fundamental abilities. Copyright © 2017 the authors 0270-6474/17/378142-08$15.00/0.

A Role for the Left Angular Gyrus in Episodic Simulation and Memory

PubMed Central

2017-01-01

Functional magnetic resonance imaging (fMRI) studies indicate that episodic simulation (i.e., imagining specific future experiences) and episodic memory (i.e., remembering specific past experiences) are associated with enhanced activity in a common set of neural regions referred to as the core network. This network comprises the hippocampus, medial prefrontal cortex, and left angular gyrus, among other regions. Because fMRI data are correlational, it is unknown whether activity increases in core network regions are critical for episodic simulation and episodic memory. In the current study, we used MRI-guided transcranial magnetic stimulation (TMS) to assess whether temporary disruption of the left angular gyrus would impair both episodic simulation and memory (16 participants, 10 females). Relative to TMS to a control site (vertex), disruption of the left angular gyrus significantly reduced the number of internal (i.e., episodic) details produced during the simulation and memory tasks, with a concomitant increase in external detail production (i.e., semantic, repetitive, or off-topic information), reflected by a significant detail by TMS site interaction. Difficulty in the simulation and memory tasks also increased after TMS to the left angular gyrus relative to the vertex. In contrast, performance in a nonepisodic control task did not differ statistically as a function of TMS site (i.e., number of free associates produced or difficulty in performing the free associate task). Together, these results are the first to demonstrate that the left angular gyrus is critical for both episodic simulation and episodic memory. SIGNIFICANCE STATEMENT Humans have the ability to imagine future episodes (i.e., episodic simulation) and remember episodes from the past (i.e., episodic memory). A wealth of neuroimaging studies have revealed that these abilities are associated with enhanced activity in a core network of neural regions, including the hippocampus, medial prefrontal cortex, and left angular gyrus. However, neuroimaging data are correlational and do not tell us whether core regions support critical processes for simulation and memory. In the current study, we used transcranial magnetic stimulation and demonstrated that temporary disruption of the left angular gyrus leads to impairments in simulation and memory. The present study provides the first causal evidence to indicate that this region is critical for these fundamental abilities. PMID:28733357

Text messaging during simulated driving.

PubMed

Drews, Frank A; Yazdani, Hina; Godfrey, Celeste N; Cooper, Joel M; Strayer, David L

2009-10-01

This research aims to identify the impact of text messaging on simulated driving performance. In the past decade, a number of on-road, epidemiological, and simulator-based studies reported the negative impact of talking on a cell phone on driving behavior. However, the impact of text messaging on simulated driving performance is still not fully understood. Forty participants engaged in both a single task (driving) and a dual task (driving and text messaging) in a high-fidelity driving simulator. Analysis of driving performance revealed that participants in the dual-task condition responded more slowly to the onset of braking lights and showed impairments in forward and lateral control compared with a driving-only condition. Moreover, text-messaging drivers were involved in more crashes than drivers not engaged in text messaging. Text messaging while driving has a negative impact on simulated driving performance. This negative impact appears to exceed the impact of conversing on a cell phone while driving. The results increase our understanding of driver distraction and have potential implications for public safety and device development.

Psychometric Characteristics of Role-Play Assessments of Social Skill in Schizophrenia

ERIC Educational Resources Information Center

Bellack, Alan S.; Brown, Clayton H.; Thomas-Lohrman, Shannon

2006-01-01

There is an extensive literature documenting that people with schizophrenia have marked impairments in social role functioning and social skill. One of the most widely employed strategies for assessing social skill has been role-play tests: simulated social interactions that are videotaped for subsequent behavioral coding. There has been…

Active Learning in Neuroscience: A Manipulative to Simulate Visual Field Defects

ERIC Educational Resources Information Center

Li, Andrew Yue-Lin; Carvalho, Helena

2016-01-01

Prevalent in 20-57% of stroke patients, visual field defects have been shown to impact quality of life. Studies have shown increased risk of falling, ambulatory difficulties, impaired reading ability, and feelings of panic in crowded or unfamiliar places in patients with visual field defects. Rehabilitation, independence, and mental health may…

Conformity of Behaviors among Medical Students: Impact on Performance of Knee Arthrocentesis in Simulation

ERIC Educational Resources Information Center

Beran, Tanya N.; McLaughlin, Kevin; Al Ansari, Ahmed; Kassam, Aliya

2013-01-01

Although the development of collaborative relationships is considered a requirement for medical education, the functioning of these relationships may be impaired by a well-documented social-psychological phenomenon known as group conformity. The authors hypothesized that students would insert a needle into an incorrect location relative to the…

Low Size, Weight and Power Concept for Mid-Wave Infrared Optical Communication Transceivers Based on Quantum Cascade Lasers

NASA Technical Reports Server (NTRS)

Luzhanskiy, Edward; Choa, Fow-Sen; Merritt, Scott; Yu, Anthony; Krainak, Michael

2015-01-01

The low complexity, low size, weight and power Mid-Wavelength Infra-Red optical communications transceiver concept presented, realized and tested in the laboratory environment. Resilience to atmospheric impairments analyzed with simulated turbulence. Performance compared to typical telecom based Short Wavelength Infra-Red transceiver.

Simulations of exercise and brain effects of acute exposure to carbon monoxide in normal and vascular-diseased persons.

EPA Science Inventory

At some level, carboxyhemoglobin (RbCO) due to inhalation of carbon monoxide (CO) reduces maximum exercise duration in normal and ischemic heart patients. At high RbCO levels in normal subjects, brain function is also affected and behavioral performance is impaired. These are fin...

The Role of Visual Speech Information in Supporting Perceptual Learning of Degraded Speech

ERIC Educational Resources Information Center

Wayne, Rachel V.; Johnsrude, Ingrid S.

2012-01-01

Following cochlear implantation, hearing-impaired listeners must adapt to speech as heard through their prosthesis. Visual speech information (VSI; the lip and facial movements of speech) is typically available in everyday conversation. Here, we investigate whether learning to understand a popular auditory simulation of speech as transduced by a…

Central and Peripheral Vision Loss Differentially Affects Contextual Cueing in Visual Search

ERIC Educational Resources Information Center

Geringswald, Franziska; Pollmann, Stefan

2015-01-01

Visual search for targets in repeated displays is more efficient than search for the same targets in random distractor layouts. Previous work has shown that this contextual cueing is severely impaired under central vision loss. Here, we investigated whether central vision loss, simulated with gaze-contingent displays, prevents the incidental…

Image Perception Wavelet Simulation and Enhancement for the Visually Impaired.

DTIC Science & Technology

1994-12-01

and Computational Harmonic Analysis, 1:54-81 (1993). 6. Cornsweet, Tom N. "The Staircase-Method in Psychophysics," The American Journal of Psychology ...of a Visual Model," Proceedings of the IEEE, 60(7):828-842 (July 1972). 33. Taylor, M. M. and C Douglas Creelman . "PEST: Efficient Estimates on

Retraining moderately impaired stroke survivors in driving-related visual attention skills.

PubMed

Akinwuntan, Abiodun E; Devos, Hannes; Verheyden, Geert; Baten, Guido; Kiekens, Carlotte; Feys, Hilde; De Weerdt, Willy

2010-01-01

Visual inattention is a major cause of road accidents and is a problem commonly experienced after stroke. This study investigated the effects of 2 training programs on performance in the Useful Field of View (UFOV), a validated test of driving-related visual attention skills. Data from 69 first-ever, moderately impaired stroke survivors who participated in a randomized controlled trial (RCT) to determine the effects of simulator training on driving after stroke were analyzed. In addition to regular interventions at a rehabilitation center, participants received 15 hours of either simulator-based driving-related training or non-computer-based cognitive training over 5 weeks. Total percentage reduction in UFOV and performance in divided and selective attention and speed of processing subtests were documented at 6 to 9 weeks (pretraining), 11 to 15 weeks (posttraining), and 6 months post stroke (follow-up). Generalized estimating equation (GEE) model revealed neither group effects nor significant interaction effects of group with time in the UFOV total score and the 3 subtests. However, there were significant within-group improvements from pre- through posttraining to follow-up for all the UFOV parameters. Post-hoc GEE analysis revealed that most improvement in both groups occurred from pre- to posttraining. Both training programs significantly improved visual attention skills of moderately impaired stroke survivors after 15 hours of training and retention of benefit lasted up to 6 months after stroke. Neither of the training programs was better than the other.

Sentence Recognition Prediction for Hearing-impaired Listeners in Stationary and Fluctuation Noise With FADE

PubMed Central

Schädler, Marc René; Warzybok, Anna; Meyer, Bernd T.; Brand, Thomas

2016-01-01

To characterize the individual patient’s hearing impairment as obtained with the matrix sentence recognition test, a simulation Framework for Auditory Discrimination Experiments (FADE) is extended here using the Attenuation and Distortion (A+D) approach by Plomp as a blueprint for setting the individual processing parameters. FADE has been shown to predict the outcome of both speech recognition tests and psychoacoustic experiments based on simulations using an automatic speech recognition system requiring only few assumptions. It builds on the closed-set matrix sentence recognition test which is advantageous for testing individual speech recognition in a way comparable across languages. Individual predictions of speech recognition thresholds in stationary and in fluctuating noise were derived using the audiogram and an estimate of the internal level uncertainty for modeling the individual Plomp curves fitted to the data with the Attenuation (A-) and Distortion (D-) parameters of the Plomp approach. The “typical” audiogram shapes from Bisgaard et al with or without a “typical” level uncertainty and the individual data were used for individual predictions. As a result, the individualization of the level uncertainty was found to be more important than the exact shape of the individual audiogram to accurately model the outcome of the German Matrix test in stationary or fluctuating noise for listeners with hearing impairment. The prediction accuracy of the individualized approach also outperforms the (modified) Speech Intelligibility Index approach which is based on the individual threshold data only. PMID:27604782

Open-field arena boundary is a primary object of exploration for Drosophila

PubMed Central

Soibam, Benjamin; Mann, Monica; Liu, Lingzhi; Tran, Jessica; Lobaina, Milena; Kang, Yuan Yuan; Gunaratne, Gemunu H; Pletcher, Scott; Roman, Gregg

2012-01-01

Drosophila adults, when placed into a novel open-field arena, initially exhibit an elevated level of activity followed by a reduced stable level of spontaneous activity and spend a majority of time near the arena edge, executing motions along the walls. In order to determine the environmental features that are responsible for the initial high activity and wall-following behavior exhibited during exploration, we examined wild-type and visually impaired mutants in arenas with different vertical surfaces. These experiments support the conclusion that the wall-following behavior of Drosophila is best characterized by a preference for the arena boundary, and not thigmotaxis or centrophobicity. In circular arenas, Drosophila mostly move in trajectories with low turn angles. Since the boundary preference could derive from highly linear trajectories, we further developed a simulation program to model the effects of turn angle on the boundary preference. In an hourglass-shaped arena with convex-angled walls that forced a straight versus wall-following choice, the simulation with constrained turn angles predicted general movement across a central gap, whereas Drosophila tend to follow the wall. Hence, low turn angled movement does not drive the boundary preference. Lastly, visually impaired Drosophila demonstrate a defect in attenuation of the elevated initial activity. Interestingly, the visually impaired w1118 activity decay defect can be rescued by increasing the contrast of the arena's edge, suggesting that the activity decay relies on visual detection of the boundary. The arena boundary is, therefore, a primary object of exploration for Drosophila. PMID:22574279

Overreliance on auditory feedback may lead to sound/syllable repetitions: simulations of stuttering and fluency-inducing conditions with a neural model of speech production.

PubMed

Civier, Oren; Tasko, Stephen M; Guenther, Frank H

2010-09-01

This paper investigates the hypothesis that stuttering may result in part from impaired readout of feedforward control of speech, which forces persons who stutter (PWS) to produce speech with a motor strategy that is weighted too much toward auditory feedback control. Over-reliance on feedback control leads to production errors which if they grow large enough, can cause the motor system to "reset" and repeat the current syllable. This hypothesis is investigated using computer simulations of a "neurally impaired" version of the DIVA model, a neural network model of speech acquisition and production. The model's outputs are compared to published acoustic data from PWS' fluent speech, and to combined acoustic and articulatory movement data collected from the dysfluent speech of one PWS. The simulations mimic the errors observed in the PWS subject's speech, as well as the repairs of these errors. Additional simulations were able to account for enhancements of fluency gained by slowed/prolonged speech and masking noise. Together these results support the hypothesis that many dysfluencies in stuttering are due to a bias away from feedforward control and toward feedback control. The reader will be able to (a) describe the contribution of auditory feedback control and feedforward control to normal and stuttered speech production, (b) summarize the neural modeling approach to speech production and its application to stuttering, and (c) explain how the DIVA model accounts for enhancements of fluency gained by slowed/prolonged speech and masking noise.

Noncredible cognitive performance at clinical evaluation of adult ADHD: An embedded validity indicator in a visuospatial working memory test.

PubMed

Fuermaier, Anselm B M; Tucha, Oliver; Koerts, Janneke; Lange, Klaus W; Weisbrod, Matthias; Aschenbrenner, Steffen; Tucha, Lara

2017-12-01

The assessment of performance validity is an essential part of the neuropsychological evaluation of adults with attention-deficit/hyperactivity disorder (ADHD). Most available tools, however, are inaccurate regarding the identification of noncredible performance. This study describes the development of a visuospatial working memory test, including a validity indicator for noncredible cognitive performance of adults with ADHD. Visuospatial working memory of adults with ADHD (n = 48) was first compared to the test performance of healthy individuals (n = 48). Furthermore, a simulation design was performed including 252 individuals who were randomly assigned to either a control group (n = 48) or to 1 of 3 simulation groups who were requested to feign ADHD (n = 204). Additional samples of 27 adults with ADHD and 69 instructed simulators were included to cross-validate findings from the first samples. Adults with ADHD showed impaired visuospatial working memory performance of medium size as compared to healthy individuals. Simulation groups committed significantly more errors and had shorter response times as compared to patients with ADHD. Moreover, binary logistic regression analysis was carried out to derive a validity index that optimally differentiates between true and feigned ADHD. ROC analysis demonstrated high classification rates of the validity index, as shown in excellent specificity (95.8%) and adequate sensitivity (60.3%). The visuospatial working memory test as presented in this study therefore appears sensitive in indicating cognitive impairment of adults with ADHD. Furthermore, the embedded validity index revealed promising results concerning the detection of noncredible cognitive performance of adults with ADHD. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Development of total maximum daily loads for bacteria impaired watershed using the comprehensive hydrology and water quality simulation model.

PubMed

Kim, Sang M; Brannan, Kevin M; Zeckoski, Rebecca W; Benham, Brian L

2014-01-01

The objective of this study was to develop bacteria total maximum daily loads (TMDLs) for the Hardware River watershed in the Commonwealth of Virginia, USA. The TMDL program is an integrated watershed management approach required by the Clean Water Act. The TMDLs were developed to meet Virginia's water quality standard for bacteria at the time, which stated that the calendar-month geometric mean concentration of Escherichia coli should not exceed 126 cfu/100 mL, and that no single sample should exceed a concentration of 235 cfu/100 mL. The bacteria impairment TMDLs were developed using the Hydrological Simulation Program-FORTRAN (HSPF). The hydrology and water quality components of HSPF were calibrated and validated using data from the Hardware River watershed to ensure that the model adequately simulated runoff and bacteria concentrations. The calibrated and validated HSPF model was used to estimate the contributions from the various bacteria sources in the Hardware River watershed to the in-stream concentration. Bacteria loads were estimated through an extensive source characterization process. Simulation results for existing conditions indicated that the majority of the bacteria came from livestock and wildlife direct deposits and pervious lands. Different source reduction scenarios were evaluated to identify scenarios that meet both the geometric mean and single sample maximum E. coli criteria with zero violations. The resulting scenarios required extreme and impractical reductions from livestock and wildlife sources. Results from studies similar to this across Virginia partially contributed to a reconsideration of the standard's applicability to TMDL development.

Driving Simulator Performance in Patients with Possible and Probable Alzheimer’s Disease

PubMed Central

Stein, Anthony C.; Dubinsky, Richard M.

2011-01-01

Drivers with more advanced stages of Alzheimer’s disease (AD) have been previously associated with an increased rate of motor vehicle accidents. Drivers suffering from early AD are also involved in, and may even cause motor vehicle accidents with greater frequency than “normal” drivers. Consequently there is considerable public concern regarding traffic safety issues for those with AD and subsequently for society, but there has been little research in understanding whether deterioration in driving ability is progressive, or has a sudden onset once the disease has reached a certain severity. The purpose of this study was to identify possible degradation in simulated driving performance that may occur at the earliest stages of AD, and compare these decrements to a control group of normal drivers. Using a single blind design, seventeen AD subjects, eight at a Clinical Dementia Rating (CDR) of 0.5 (possible AD) and nine at a CDR of 1 (probable AD), were compared to 63 cognitively normal, elderly controls. All subjects were trained to drive a computerized interactive driving simulator and then tested on a 19.3 km (12 mile) test course. The AD subjects demonstrated impaired driving performance when compared to the controls. The simulated driving performance of the CDR 1 AD subjects was so degraded that it would be regarded as unsafe by standard assessment criteria. The CDR 0.5 subjects made similar errors, suggesting that driving impairment may occur at the earliest stages of the disease. Further work will be necessary to determine the significance of these findings. PMID:22105407

Control Characteristics of Alcohol-Impaired Operators

NASA Technical Reports Server (NTRS)

Jex, Henry R.; McRuer, Duane T.; Allen, R. Wade; Klein, Richard H.

1974-01-01

Although the operation of vehicles like airplanes, cars, and bicycles involves a complex array of perceptual, decision and control activities, most accident statistics clearly show that intoxicated operators are a dominant cause of accidents, and not the difficulty of the task itself. This paper summarizes some recent research on the nature of the impairment of operator control under blood alcohol concentrations (BAC) up to above 0.16 percent. Alcohol toxicity is shown to be quite specific with respect to visual-motor functions involved in control of a vehicle, and experiments with a generalized workload task and special driving simulator show how these are reflected in terms of changes in operator control parameters such as response latency, gains, stability margins, and coherency.

Soft-information flipping approach in multi-head multi-track BPMR systems

NASA Astrophysics Data System (ADS)

Warisarn, C.; Busyatras, W.; Myint, L. M. M.

2018-05-01

Inter-track interference is one of the most severe impairments in bit-patterned media recording system. This impairment can be effectively handled by a modulation code and a multi-head array jointly processing multiple tracks; however, such a modulation constraint has never been utilized to improve the soft-information. Therefore, this paper proposes the utilization of modulation codes with an encoded constraint defined by the criteria for soft-information flipping during a three-track data detection process. Moreover, we also investigate the optimal offset position of readheads to provide the most improvement in system performance. The simulation results indicate that the proposed systems with and without position jitter are significantly superior to uncoded systems.

Mapping correspondence between facial mimicry and emotion recognition in healthy subjects.

PubMed

Ponari, Marta; Conson, Massimiliano; D'Amico, Nunzia Pina; Grossi, Dario; Trojano, Luigi

2012-12-01

We aimed at verifying the hypothesis that facial mimicry is causally and selectively involved in emotion recognition. For this purpose, in Experiment 1, we explored the effect of tonic contraction of muscles in upper or lower half of participants' face on their ability to recognize emotional facial expressions. We found that the "lower" manipulation specifically impaired recognition of happiness and disgust, the "upper" manipulation impaired recognition of anger, while both manipulations affected recognition of fear; recognition of surprise and sadness were not affected by either blocking manipulations. In Experiment 2, we verified whether emotion recognition is hampered by stimuli in which an upper or lower half-face showing an emotional expression is combined with a neutral half-face. We found that the neutral lower half-face interfered with recognition of happiness and disgust, whereas the neutral upper half impaired recognition of anger; recognition of fear and sadness was impaired by both manipulations, whereas recognition of surprise was not affected by either manipulation. Taken together, the present findings support simulation models of emotion recognition and provide insight into the role of mimicry in comprehension of others' emotional facial expressions. PsycINFO Database Record (c) 2012 APA, all rights reserved.

Effects of reverberation and noise on speech intelligibility in normal-hearing and aided hearing-impaired listeners.

PubMed

Xia, Jing; Xu, Buye; Pentony, Shareka; Xu, Jingjing; Swaminathan, Jayaganesh

2018-03-01

Many hearing-aid wearers have difficulties understanding speech in reverberant noisy environments. This study evaluated the effects of reverberation and noise on speech recognition in normal-hearing listeners and hearing-impaired listeners wearing hearing aids. Sixteen typical acoustic scenes with different amounts of reverberation and various types of noise maskers were simulated using a loudspeaker array in an anechoic chamber. Results showed that, across all listening conditions, speech intelligibility of aided hearing-impaired listeners was poorer than normal-hearing counterparts. Once corrected for ceiling effects, the differences in the effects of reverberation on speech intelligibility between the two groups were much smaller. This suggests that, at least, part of the difference in susceptibility to reverberation between normal-hearing and hearing-impaired listeners was due to ceiling effects. Across both groups, a complex interaction between the noise characteristics and reverberation was observed on the speech intelligibility scores. Further fine-grained analyses of the perception of consonants showed that, for both listener groups, final consonants were more susceptible to reverberation than initial consonants. However, differences in the perception of specific consonant features were observed between the groups.

Stress Counter-Response Training Via Physiological Self-Regulation During Flight Simulation

NASA Technical Reports Server (NTRS)

Palsson, Olafur S.

2000-01-01

This study provided the first evaluation of a new training concept and technology aimed at training pilots to maintain physiological equilibrium during circumstances in an airplane cockpit. Thirty healthy subjects (16 males and 14 females) between the ages of 18 and 35 were randomized into two study groups, A and B. Subjects participated individually in a sequence of four study sessions. In the first visit, subjects were taught to operate a desktop fighter jet flight simulation program. In the three sessions that followed, subjects in group A were trained to minimize their autonomic deviation from baseline values while operating the desktop flight simulation. This was done by making their skin conductance and hand temperature deviations from baseline impair the functionality of the aircraft controls. Subjects also received auditory and visual cues about their autonomic deviation, and were instructed to keep these within pre-set limits to retain full control of the aircraft. Subjects in group B were subjected to periods of impaired aircraft functionality independent of their physiologic activity, and thus served as a control group. No statistically significant group differences were found in the flight performance scores from the three training sessions, and post-training flight performance scores of the two groups were not different. We conclude that this study did not provide clear support for this training methodology in optimizing pilot performance. However, a number of shortcomings in the current status of this training methodology may account for the lack of demonstrable training benefit to the experimental group. Suggested future modifications for research on this training methodology include: Limiting the amount of instrument impairment resulting from physiological deviations; conducting a greater number of physiological training sessions per subject; using pre-post training performance tests which invoke a greater amount of stress in subjects; and developing a more detailed performance scoring system.

Effects of head-down-tilt bed rest on cerebral hemodynamics during orthostatic stress

NASA Technical Reports Server (NTRS)

Zhang, R.; Zuckerman, J. H.; Pawelczyk, J. A.; Levine, B. D.; Blomqvist, C. G. (Principal Investigator)

1997-01-01

Our aim was to determine whether the adaptation to simulated microgravity (microG) impairs regulation of cerebral blood flow (CBF) during orthostatic stress and contributes to orthostatic intolerance. Twelve healthy subjects (aged 24 +/- 5 yr) underwent 2 wk of -6 degrees head-down-tilt (HDT) bed rest to simulate hemodynamic changes that occur when humans are exposed to microG. CBF velocity in the middle cerebral artery (transcranial Doppler), blood pressure, cardiac output (acetylene rebreathing), and forearm blood flow were measured at each level of a ramped protocol of lower body negative pressure (LBNP; -15, -30, and -40 mmHg x 5 min, -50 mmHg x 3 min, then -10 mmHg every 3 min to presyncope) before and after bed rest. Orthostatic tolerance was assessed by using the cumulative stress index (CSI; mmHg x minutes) for the LBNP protocol. After bed rest, each individual's orthostatic tolerance was reduced, with the group CSI decreased by 24% associated with greater decreases in cardiac output and greater increases in systemic vascular resistance at each level of LBNP. Before bed rest, mean CBF velocity decreased by 14, 10, and 45% at -40 mmHg, -50 mmHg, and maximal LBNP, respectively. After bed rest, mean velocity decreased by 16% at -30 mmHg and by 21, 35, and 39% at -40 mmHg, -50 mmHg, and maximal LBNP, respectively. Compared with pre-bed rest, post-bed-rest mean velocity was less by 11, 10, and 21% at -30, -40, and -50 mmHg, respectively. However, there was no significant difference at maximal LBNP. We conclude that cerebral autoregulation during orthostatic stress is impaired by adaptation to simulated microG as evidenced by an earlier and greater fall in CBF velocity during LBNP. We speculate that impairment of cerebral autoregulation may contribute to the reduced orthostatic tolerance after bed rest.

Counterfactual Thinking Deficit in Huntington's Disease.

PubMed

Solca, Federica; Poletti, Barbara; Zago, Stefano; Crespi, Chiara; Sassone, Francesca; Lafronza, Annalisa; Maraschi, Anna Maria; Sassone, Jenny; Silani, Vincenzo; Ciammola, Andrea

2015-01-01

Counterfactual thinking (CFT) refers to the generation of mental simulations of alternatives to past events, actions and outcomes. CFT is a pervasive cognitive feature in every-day life and is closely related to decision-making, planning and problem-solving - all of which are cognitive processes linked to unimpaired frontal lobe functioning. Huntington's Disease (HD) is a neurodegenerative disorder characterised by motor, behavioral and cognitive dysfunctions. Because an impairment in frontal and executive functions has been described in HD, we hypothesised that HD patients may have a CFT impairment. Tests of spontaneous counterfactual thoughts and counterfactual-derived inferences were administered to 24 symptomatic HD patients and 24 age- and sex-matched healthy subjects. Our results show a significant impairment in the spontaneous generation of CFT and low performance on the Counterfactual Inference Test (CIT) in HD patients. Low performance on the spontaneous CFT test significantly correlates with impaired attention abilities, verbal fluency and frontal lobe efficiency, as measured by Trail Making Test - Part A, Phonemic Verbal Fluency Test and FAB. Spontaneous CFT and the use of this type of reasoning are impaired in HD patients. This deficit may be related to frontal lobe dysfunction, which is a hallmark of HD. Because CFT has a pervasive role in patients' daily lives regarding their planning, decision making and problem solving skills, cognitive rehabilitation may improve HD patients' ability to analyse current behaviors and future actions.

Effects of acidification on olfactory-mediated behaviour in freshwater and marine ecosystems: a synthesis

PubMed Central

Leduc, Antoine O. H. C.; Munday, Philip L.; Brown, Grant E.; Ferrari, Maud C. O.

2013-01-01

For many aquatic organisms, olfactory-mediated behaviour is essential to the maintenance of numerous fitness-enhancing activities, including foraging, reproduction and predator avoidance. Studies in both freshwater and marine ecosystems have demonstrated significant impacts of anthropogenic acidification on olfactory abilities of fish and macroinvertebrates, leading to impaired behavioural responses, with potentially far-reaching consequences to population dynamics and community structure. Whereas the ecological impacts of impaired olfactory-mediated behaviour may be similar between freshwater and marine ecosystems, the underlying mechanisms are quite distinct. In acidified freshwater, molecular change to chemical cues along with reduced olfaction sensitivity appear to be the primary causes of olfactory-mediated behavioural impairment. By contrast, experiments simulating future ocean acidification suggest that interference of high CO2 with brain neurotransmitter function is the primary cause for olfactory-mediated behavioural impairment in fish. Different physico-chemical characteristics between marine and freshwater systems are probably responsible for these distinct mechanisms of impairment, which, under globally rising CO2 levels, may lead to strikingly different consequences to olfaction. While fluctuations in pH may occur in both freshwater and marine ecosystems, marine habitat will remain alkaline despite future ocean acidification caused by globally rising CO2 levels. In this synthesis, we argue that ecosystem-specific mechanisms affecting olfaction need to be considered for effective management and conservation practices. PMID:23980246

Effects of acidification on olfactory-mediated behaviour in freshwater and marine ecosystems: a synthesis.

PubMed

Leduc, Antoine O H C; Munday, Philip L; Brown, Grant E; Ferrari, Maud C O

2013-01-01

For many aquatic organisms, olfactory-mediated behaviour is essential to the maintenance of numerous fitness-enhancing activities, including foraging, reproduction and predator avoidance. Studies in both freshwater and marine ecosystems have demonstrated significant impacts of anthropogenic acidification on olfactory abilities of fish and macroinvertebrates, leading to impaired behavioural responses, with potentially far-reaching consequences to population dynamics and community structure. Whereas the ecological impacts of impaired olfactory-mediated behaviour may be similar between freshwater and marine ecosystems, the underlying mechanisms are quite distinct. In acidified freshwater, molecular change to chemical cues along with reduced olfaction sensitivity appear to be the primary causes of olfactory-mediated behavioural impairment. By contrast, experiments simulating future ocean acidification suggest that interference of high CO2 with brain neurotransmitter function is the primary cause for olfactory-mediated behavioural impairment in fish. Different physico-chemical characteristics between marine and freshwater systems are probably responsible for these distinct mechanisms of impairment, which, under globally rising CO2 levels, may lead to strikingly different consequences to olfaction. While fluctuations in pH may occur in both freshwater and marine ecosystems, marine habitat will remain alkaline despite future ocean acidification caused by globally rising CO2 levels. In this synthesis, we argue that ecosystem-specific mechanisms affecting olfaction need to be considered for effective management and conservation practices.

Phonological and semantic processing during comprehension in Wernicke's aphasia: An N400 and Phonological Mapping Negativity Study.

PubMed

Robson, Holly; Pilkington, Emma; Evans, Louise; DeLuca, Vincent; Keidel, James L

2017-06-01

Comprehension impairments in Wernicke's aphasia are thought to result from a combination of impaired phonological and semantic processes. However, the relationship between these cognitive processes and language comprehension has only been inferred through offline neuropsychological tasks. This study used ERPs to investigate phonological and semantic processing during online single word comprehension. EEG was recorded in a group of Wernicke's aphasia n=8 and control participants n=10 while performing a word-picture verification task. The N400 and Phonological Mapping Negativity/Phonological Mismatch Negativity (PMN) event-related potential components were investigated as an index of semantic and phonological processing, respectively. Individuals with Wernicke's aphasia displayed reduced and inconsistent N400 and PMN effects in comparison to control participants. Reduced N400 effects in the WA group were simulated in the control group by artificially degrading speech perception. Correlation analyses in the Wernicke's aphasia group found that PMN but not N400 amplitude was associated with behavioural word-picture verification performance. The results confirm impairments at both phonological and semantic stages of comprehension in Wernicke's aphasia. However, reduced N400 responses in Wernicke's aphasia are at least partially attributable to earlier phonological processing impairments. The results provide further support for the traditional model of Wernicke's aphasia which claims a causative link between phonological processing and language comprehension impairments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Vowel perception by noise masked normal-hearing young adults

NASA Astrophysics Data System (ADS)

Richie, Carolyn; Kewley-Port, Diane; Coughlin, Maureen

2005-08-01

This study examined vowel perception by young normal-hearing (YNH) adults, in various listening conditions designed to simulate mild-to-moderate sloping sensorineural hearing loss. YNH listeners were individually age- and gender-matched to young hearing-impaired (YHI) listeners tested in a previous study [Richie et al., J. Acoust. Soc. Am. 114, 2923-2933 (2003)]. YNH listeners were tested in three conditions designed to create equal audibility with the YHI listeners; a low signal level with and without a simulated hearing loss, and a high signal level with a simulated hearing loss. Listeners discriminated changes in synthetic vowel tokens /smcapi e ɛ invv æ/ when F1 or F2 varied in frequency. Comparison of YNH with YHI results failed to reveal significant differences between groups in terms of performance on vowel discrimination, in conditions of similar audibility by using both noise masking to elevate the hearing thresholds of the YNH and applying frequency-specific gain to the YHI listeners. Further, analysis of learning curves suggests that while the YHI listeners completed an average of 46% more test blocks than YNH listeners, the YHI achieved a level of discrimination similar to that of the YNH within the same number of blocks. Apparently, when age and gender are closely matched between young hearing-impaired and normal-hearing adults, performance on vowel tasks may be explained by audibility alone.

Next-day residual effects of gabapentin, diphenhydramine, and triazolam on simulated driving performance in healthy volunteers: a phase 3, randomized, double-blind, placebo-controlled, crossover trial.

PubMed

Kay, Gary G; Schwartz, Howard I; Wingertzahn, Mark A; Jayawardena, Shyamalie; Rosenberg, Russell P

2016-05-01

Next-day residual effects of a nighttime dose of gabapentin 250 mg were evaluated on simulated driving performance in healthy participants in a randomized, placebo-controlled, double-blind, multicenter, four-period crossover study that included diphenhydramine citrate 76 mg and triazolam 0.5 mg. At treatment visits, participants (n = 59) were dosed at ~23:30, went to bed immediately, and awakened 6.5 h postdose for evaluation. The primary endpoint was the standard deviation of lateral position for the 100-km driving scenario. Additional measures of driving, sleepiness, and cognition were included. Study sensitivity was established with triazolam, which demonstrated significant next-day impairment on all driving endpoints, relative to placebo (p < 0.001). Gabapentin demonstrated noninferiority to placebo on standard deviation of lateral position and speed deviation but not for lane excursions. Diphenhydramine citrate demonstrated significant impairment relative to gabapentin and placebo on speed deviation (p < 0.05). Other comparisons were either nonsignificant or statistically ineligible per planned, sequential comparisons. Secondary endpoints for sleepiness and cognitive performance were supportive of these conclusions. Together, these data suggest that low-dose gabapentin had no appreciable next-day effects on simulated driving performance or cognitive functioning. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Simulating single word processing in the classic aphasia syndromes based on the Wernicke-Lichtheim-Geschwind theory.

PubMed

Weems, Scott A; Reggia, James A

2006-09-01

The Wernicke-Lichtheim-Geschwind (WLG) theory of the neurobiological basis of language is of great historical importance, and it continues to exert a substantial influence on most contemporary theories of language in spite of its widely recognized limitations. Here, we suggest that neurobiologically grounded computational models based on the WLG theory can provide a deeper understanding of which of its features are plausible and where the theory fails. As a first step in this direction, we created a model of the interconnected left and right neocortical areas that are most relevant to the WLG theory, and used it to study visual-confrontation naming, auditory repetition, and auditory comprehension performance. No specific functionality is assigned a priori to model cortical regions, other than that implicitly present due to their locations in the cortical network and a higher learning rate in left hemisphere regions. Following learning, the model successfully simulates confrontation naming and word repetition, and acquires a unique internal representation in parietal regions for each named object. Simulated lesions to the language-dominant cortical regions produce patterns of single word processing impairment reminiscent of those postulated historically in the classic aphasia syndromes. These results indicate that WLG theory, instantiated as a simple interconnected network of model neocortical regions familiar to any neuropsychologist/neurologist, captures several fundamental "low-level" aspects of neurobiological word processing and their impairment in aphasia.

Computational and empirical simulations of selective memory impairments: Converging evidence for a single-system account of memory dissociations.

PubMed

Curtis, Evan T; Jamieson, Randall K

2018-04-01

Current theory has divided memory into multiple systems, resulting in a fractionated account of human behaviour. By an alternative perspective, memory is a single system. However, debate over the details of different single-system theories has overshadowed the converging agreement among them, slowing the reunification of memory. Evidence in favour of dividing memory often takes the form of dissociations observed in amnesia, where amnesic patients are impaired on some memory tasks but not others. The dissociations are taken as evidence for separate explicit and implicit memory systems. We argue against this perspective. We simulate two key dissociations between classification and recognition in a computational model of memory, A Theory of Nonanalytic Association. We assume that amnesia reflects a quantitative difference in the quality of encoding. We also present empirical evidence that replicates the dissociations in healthy participants, simulating amnesic behaviour by reducing study time. In both analyses, we successfully reproduce the dissociations. We integrate our computational and empirical successes with the success of alternative models and manipulations and argue that our demonstrations, taken in concert with similar demonstrations with similar models, provide converging evidence for a more general set of single-system analyses that support the conclusion that a wide variety of memory phenomena can be explained by a unified and coherent set of principles.

The NEST Dry-Run Mode: Efficient Dynamic Analysis of Neuronal Network Simulation Code.

PubMed

Kunkel, Susanne; Schenck, Wolfram

2017-01-01

NEST is a simulator for spiking neuronal networks that commits to a general purpose approach: It allows for high flexibility in the design of network models, and its applications range from small-scale simulations on laptops to brain-scale simulations on supercomputers. Hence, developers need to test their code for various use cases and ensure that changes to code do not impair scalability. However, running a full set of benchmarks on a supercomputer takes up precious compute-time resources and can entail long queuing times. Here, we present the NEST dry-run mode, which enables comprehensive dynamic code analysis without requiring access to high-performance computing facilities. A dry-run simulation is carried out by a single process, which performs all simulation steps except communication as if it was part of a parallel environment with many processes. We show that measurements of memory usage and runtime of neuronal network simulations closely match the corresponding dry-run data. Furthermore, we demonstrate the successful application of the dry-run mode in the areas of profiling and performance modeling.

The NEST Dry-Run Mode: Efficient Dynamic Analysis of Neuronal Network Simulation Code

PubMed Central

Kunkel, Susanne; Schenck, Wolfram

2017-01-01

NEST is a simulator for spiking neuronal networks that commits to a general purpose approach: It allows for high flexibility in the design of network models, and its applications range from small-scale simulations on laptops to brain-scale simulations on supercomputers. Hence, developers need to test their code for various use cases and ensure that changes to code do not impair scalability. However, running a full set of benchmarks on a supercomputer takes up precious compute-time resources and can entail long queuing times. Here, we present the NEST dry-run mode, which enables comprehensive dynamic code analysis without requiring access to high-performance computing facilities. A dry-run simulation is carried out by a single process, which performs all simulation steps except communication as if it was part of a parallel environment with many processes. We show that measurements of memory usage and runtime of neuronal network simulations closely match the corresponding dry-run data. Furthermore, we demonstrate the successful application of the dry-run mode in the areas of profiling and performance modeling. PMID:28701946

Curbing the DUI offender’s self-efficacy to drink and drive: A laboratory study

PubMed Central

Roberts, Walter; Fillmore, Mark T.

2017-01-01

Background People arrested for driving under the influence of alcohol (DUI) are at high risk to reoffend. One reason for this high rate of recidivism among DUI offenders is that these individuals systematically underestimate the degree to which alcohol impairs their ability to drive. This study compared perceived and objective driving ability following alcohol and performance feedback in drivers with and without a history of DUI. Method Adult drivers with (n = 20) and without (n = 20) a history of DUI arrest attended two dose challenge sessions where they received 0.64 g/kg alcohol or placebo, completed a simulated driving task, and provided measures of subjective impairment. They attended a third retesting session where they received feedback that they were impaired by alcohol. They received 0.64 g/kg alcohol and their objective and perceived driving ability was retested. Results Both groups showed significant impairment of driving performance following 0.64 g/kg alcohol compared to placebo. DUI offenders rated themselves as less impaired than controls. After performance feedback, self-reported impairment during the alcohol retest increased for DUI offenders but not for controls. There was no effect of performance feedback on objective driving ability. Conclusions These results support the notion that under alcohol DUI offenders characteristically perceive themselves as better able to drive than non-offenders. These perceptions can be tempered by performance feedback. To the extent that perceived ability to drive safely after drinking contributes to DUI and its recidivism, feedback geared towards lowering this self-efficacy could reduce willingness to engage in this behavior. PMID:28152449

Pump RIN-induced impairments in unrepeatered transmission systems using distributed Raman amplifier.

PubMed

Cheng, Jingchi; Tang, Ming; Lau, Alan Pak Tao; Lu, Chao; Wang, Liang; Dong, Zhenhua; Bilal, Syed Muhammad; Fu, Songnian; Shum, Perry Ping; Liu, Deming

2015-05-04

High spectral efficiency modulation format based unrepeatered transmission systems using distributed Raman amplifier (DRA) have attracted much attention recently. To enhance the reach and optimize system performance, careful design of DRA is required based on the analysis of various types of impairments and their balance. In this paper, we study various pump RIN induced distortions on high spectral efficiency modulation formats. The vector theory of both 1st and higher-order stimulated Raman scattering (SRS) effect using Jones-matrix formalism is presented. The pump RIN will induce three types of distortion on high spectral efficiency signals: intensity noise stemming from SRS, phase noise stemming from cross phase modulation (XPM), and polarization crosstalk stemming from cross polarization modulation (XPolM). An analytical model for the statistical property of relative phase noise (RPN) in higher order DRA without dealing with complex vector theory is derived. The impact of pump RIN induced impairments are analyzed in polarization-multiplexed (PM)-QPSK and PM-16QAM-based unrepeatered systems simulations using 1st, 2nd and 3rd-order forward pumped Raman amplifier. It is shown that at realistic RIN levels, negligible impairments will be induced to PM-QPSK signals in 1st and 2nd order DRA, while non-negligible impairments will occur in 3rd order case. PM-16QAM signals suffer more penalties compared to PM-QPSK with the same on-off gain where both 2nd and 3rd order DRA will cause non-negligible performance degradations. We also investigate the performance of digital signal processing (DSP) algorithms to mitigate such impairments.

Nursing students' knowledge of and performance in communicating with patients with hearing impairment.

PubMed

Adib-Hajbaghery, Mohsen; Rezaei-Shahsavarloo, Zahra

2015-04-01

The present study aimed to investigate nursing students' knowledge of and performance in communicating with patients with hearing impairment. A cross-sectional study was conducted on all senior nursing students (n = 71) in a nursing school in Iran in 2013. Data collection was performed with a demographics questionnaire, knowledge questionnaire, and performance assessment checklist. Two stages were designed to evaluate the students. In the first stage, students conducted an interview with a simulated patient with hearing impairment who experienced chest pain. In the second stage, students answered the knowledge questionnaire. Descriptive statistics, independent sample Student's t-test, and Pearson correlation coefficient were used to analyze the data. In total, 11.3% of participants had a history of caring for a patient with hearing impairment. The majority of students evaluated their performance in communicating with such patients at a moderate level. A significant difference was observed between the mean score of knowledge in men and women (P = 0.05), and male students gained higher scores. In total, 61.5% of the students had low to very low levels of knowledge and 87.3% of them had weak to very weak performance in communicating with patients with hearing impairment. Nursing students are lacking in knowledge and skills required for effective communication with patients with hearing impairment. Nurse educators should pay more attention to this issue as it is their responsibility to prepare nurses who are competent to deal with common issues they will face in practice. © 2014 The Authors. Japan Journal of Nursing Science © 2014 Japan Academy of Nursing Science.

Ketogenic diet improves the spatial memory impairment caused by exposure to hypobaric hypoxia through increased acetylation of histones in rats.

PubMed

Zhao, Ming; Huang, Xin; Cheng, Xiang; Lin, Xiao; Zhao, Tong; Wu, Liying; Yu, Xiaodan; Wu, Kuiwu; Fan, Ming; Zhu, Lingling

2017-01-01

Exposure to hypobaric hypoxia causes neuron cell damage, resulting in impaired cognitive function. Effective interventions to antagonize hypobaric hypoxia-induced memory impairment are in urgent need. Ketogenic diet (KD) has been successfully used to treat drug-resistant epilepsy and improves cognitive behaviors in epilepsy patients and other pathophysiological animal models. In the present study, we aimed to explore the potential beneficial effects of a KD on memory impairment caused by hypobaric hypoxia and the underlying possible mechanisms. We showed that the KD recipe used was ketogenic and increased plasma levels of ketone bodies, especially β-hydroxybutyrate. The results of the behavior tests showed that the KD did not affect general locomotor activity but obviously promoted spatial learning. Moreover, the KD significantly improved the spatial memory impairment caused by hypobaric hypoxia (simulated altitude of 6000 m, 24 h). In addition, the improving-effect of KD was mimicked by intraperitoneal injection of BHB. The western blot and immunohistochemistry results showed that KD treatment not only increased the acetylated levels of histone H3 and histone H4 compared to that of the control group but also antagonized the decrease in the acetylated histone H3 and H4 when exposed to hypobaric hypoxia. Furthermore, KD-hypoxia treatment also promoted PKA/CREB activation and BDNF protein expression compared to the effects of hypoxia alone. These results demonstrated that KD is a promising strategy to improve spatial memory impairment caused by hypobaric hypoxia, in which increased modification of histone acetylation plays an important role.

The herbal medicine daikenchuto ameliorates an impaired anorectal motor activity in postoperative pediatric patients with an anorectal malformation--a pilot study.

PubMed

Takagi, Akiko; Yagi, Minoru; Tanaka, Yoshiaki; Asagiri, Kimio; Asakawa, Takahiro; Tanaka, Hiroaki; Ishii, Shinji; Egami, Hideaki; Akaiwa, Masao; Tsuru, Tomomitsu

2010-01-01

Fecoflowmetry (FFM) has been introduced to simulate natural anorectal evacuation. So far, few reports have described the effect of the herbal medicine Daikenchuto (DKT) on impaired anorectal motor function. The aim of this pilot study was to assess anorectal motor function by FFM in postoperatively impaired patients with an anorectal malformation (ARM) before and after administration of DKT. Six postoperative patients with ARM (mean age, 7.8 years) who complained of intractable constipation with soiling in spite of administration of magnesia as a laxative were assessed over an extended period. These patients received 0.3 g/kg/d of DKT for an average of 128 days. Evacuative rate and maximum fecal stream flow were seen to increase significantly after administration of DKT when compared with values before administration of DKT. In conclusion, DKT had a favorable clinical effect on anorectal motor function in postoperative patients with ARM.

Development of a virtual reality assessment of everyday living skills.

PubMed

Ruse, Stacy A; Davis, Vicki G; Atkins, Alexandra S; Krishnan, K Ranga R; Fox, Kolleen H; Harvey, Philip D; Keefe, Richard S E

2014-04-23

Cognitive impairments affect the majority of patients with schizophrenia and these impairments predict poor long term psychosocial outcomes.  Treatment studies aimed at cognitive impairment in patients with schizophrenia not only require demonstration of improvements on cognitive tests, but also evidence that any cognitive changes lead to clinically meaningful improvements.  Measures of "functional capacity" index the extent to which individuals have the potential to perform skills required for real world functioning.  Current data do not support the recommendation of any single instrument for measurement of functional capacity.  The Virtual Reality Functional Capacity Assessment Tool (VRFCAT) is a novel, interactive gaming based measure of functional capacity that uses a realistic simulated environment to recreate routine activities of daily living. Studies are currently underway to evaluate and establish the VRFCAT's sensitivity, reliability, validity, and practicality. This new measure of functional capacity is practical, relevant, easy to use, and has several features that improve validity and sensitivity of measurement of function in clinical trials of patients with CNS disorders.

MEDIAL TEMPORAL LOBE CONTRIBUTIONS TO FUTURE THINKING: EVIDENCE FROM NEUROIMAGING AND AMNESIA.

PubMed

Verfaellie, Mieke; Race, Elizabeth; Keane, Margaret M

2012-09-01

Following early amnesic case reports, there is now considerable evidence suggesting a link between remembering the past and envisioning the future. This link is evident in the overlap in neural substrates as well as cognitive processes involved in both kinds of tasks. While constructing a future narrative requires multiple processes, neuroimaging and lesion data converge on a critical role for the medial temporal lobes (MTL) in retrieving and recombining details from memory in the service of novel simulations. Deficient detail retrieval and recombination may lead to impairments not only in episodic, but also in semantic prospection. MTL contributions to scene construction and mental time travel may further compound impairments in amnesia on tasks that pose additional demands on these processes, but are unlikely to form the core deficit underlying amnesics' cross-domain future thinking impairment. Future studies exploring the role of episodic memory in other forms of self-projection or future-oriented behaviour may elucidate further the adaptive role of memory.

MEDIAL TEMPORAL LOBE CONTRIBUTIONS TO FUTURE THINKING: EVIDENCE FROM NEUROIMAGING AND AMNESIA

PubMed Central

Verfaellie, Mieke; Race, Elizabeth; Keane, Margaret M.

2013-01-01

Following early amnesic case reports, there is now considerable evidence suggesting a link between remembering the past and envisioning the future. This link is evident in the overlap in neural substrates as well as cognitive processes involved in both kinds of tasks. While constructing a future narrative requires multiple processes, neuroimaging and lesion data converge on a critical role for the medial temporal lobes (MTL) in retrieving and recombining details from memory in the service of novel simulations. Deficient detail retrieval and recombination may lead to impairments not only in episodic, but also in semantic prospection. MTL contributions to scene construction and mental time travel may further compound impairments in amnesia on tasks that pose additional demands on these processes, but are unlikely to form the core deficit underlying amnesics’ cross-domain future thinking impairment. Future studies exploring the role of episodic memory in other forms of self-projection or future-oriented behaviour may elucidate further the adaptive role of memory. PMID:23447709

Cannabidiol reduces the anxiety induced by simulated public speaking in treatment-naïve social phobia patients.

PubMed

Bergamaschi, Mateus M; Queiroz, Regina Helena Costa; Chagas, Marcos Hortes Nisihara; de Oliveira, Danielle Chaves Gomes; De Martinis, Bruno Spinosa; Kapczinski, Flávio; Quevedo, João; Roesler, Rafael; Schröder, Nadja; Nardi, Antonio E; Martín-Santos, Rocio; Hallak, Jaime Eduardo Cecílio; Zuardi, Antonio Waldo; Crippa, José Alexandre S

2011-05-01

Generalized Social Anxiety Disorder (SAD) is one of the most common anxiety conditions with impairment in social life. Cannabidiol (CBD), one major non-psychotomimetic compound of the cannabis sativa plant, has shown anxiolytic effects both in humans and in animals. This preliminary study aimed to compare the effects of a simulation public speaking test (SPST) on healthy control (HC) patients and treatment-naïve SAD patients who received a single dose of CBD or placebo. A total of 24 never-treated patients with SAD were allocated to receive either CBD (600 mg; n=12) or placebo (placebo; n=12) in a double-blind randomized design 1 h and a half before the test. The same number of HC (n=12) performed the SPST without receiving any medication. Each volunteer participated in only one experimental session in a double-blind procedure. Subjective ratings on the Visual Analogue Mood Scale (VAMS) and Negative Self-Statement scale (SSPS-N) and physiological measures (blood pressure, heart rate, and skin conductance) were measured at six different time points during the SPST. The results were submitted to a repeated-measures analysis of variance. Pretreatment with CBD significantly reduced anxiety, cognitive impairment and discomfort in their speech performance, and significantly decreased alert in their anticipatory speech. The placebo group presented higher anxiety, cognitive impairment, discomfort, and alert levels when compared with the control group as assessed with the VAMS. The SSPS-N scores evidenced significant increases during the testing of placebo group that was almost abolished in the CBD group. No significant differences were observed between CBD and HC in SSPS-N scores or in the cognitive impairment, discomfort, and alert factors of VAMS. The increase in anxiety induced by the SPST on subjects with SAD was reduced with the use of CBD, resulting in a similar response as the HC.

Cannabidiol Reduces the Anxiety Induced by Simulated Public Speaking in Treatment-Naïve Social Phobia Patients

PubMed Central

Bergamaschi, Mateus M; Queiroz, Regina Helena Costa; Chagas, Marcos Hortes Nisihara; de Oliveira, Danielle Chaves Gomes; De Martinis, Bruno Spinosa; Kapczinski, Flávio; Quevedo, João; Roesler, Rafael; Schröder, Nadja; Nardi, Antonio E; Martín-Santos, Rocio; Hallak, Jaime Eduardo Cecílio; Zuardi, Antonio Waldo; Crippa, José Alexandre S

2011-01-01

Generalized Social Anxiety Disorder (SAD) is one of the most common anxiety conditions with impairment in social life. Cannabidiol (CBD), one major non-psychotomimetic compound of the cannabis sativa plant, has shown anxiolytic effects both in humans and in animals. This preliminary study aimed to compare the effects of a simulation public speaking test (SPST) on healthy control (HC) patients and treatment-naïve SAD patients who received a single dose of CBD or placebo. A total of 24 never-treated patients with SAD were allocated to receive either CBD (600 mg; n=12) or placebo (placebo; n=12) in a double-blind randomized design 1 h and a half before the test. The same number of HC (n=12) performed the SPST without receiving any medication. Each volunteer participated in only one experimental session in a double-blind procedure. Subjective ratings on the Visual Analogue Mood Scale (VAMS) and Negative Self-Statement scale (SSPS-N) and physiological measures (blood pressure, heart rate, and skin conductance) were measured at six different time points during the SPST. The results were submitted to a repeated-measures analysis of variance. Pretreatment with CBD significantly reduced anxiety, cognitive impairment and discomfort in their speech performance, and significantly decreased alert in their anticipatory speech. The placebo group presented higher anxiety, cognitive impairment, discomfort, and alert levels when compared with the control group as assessed with the VAMS. The SSPS-N scores evidenced significant increases during the testing of placebo group that was almost abolished in the CBD group. No significant differences were observed between CBD and HC in SSPS-N scores or in the cognitive impairment, discomfort, and alert factors of VAMS. The increase in anxiety induced by the SPST on subjects with SAD was reduced with the use of CBD, resulting in a similar response as the HC. PMID:21307846

Manual control analysis of drug effects on driving performance

NASA Technical Reports Server (NTRS)

Smiley, A.; Ziedman, K.; Moskowitz, H.

1981-01-01

The effects of secobarbital, diazepam, alcohol, and marihuana on car-driver transfer functions obtained using a driving simulator were studied. The first three substances, all CNS depressants, reduced gain, crossover frequency, and coherence which resulted in poorer tracking performance. Marihuana also impaired tracking performance but the only effect on the transfer function parameters was to reduce coherence.

Simulating Sli: General Cognitive Processing Stressors Can Produce a Specific Linguistic Profile.

ERIC Educational Resources Information Center

Hayiou-Thomas, Marianna E.; Bishop, Dorothy V.M.; Plunkett, Kim

2004-01-01

This study attempted to model specific language impairment (SLI) in a group of 6year-old children with typically developing language by introducing cognitive stress factors into a grammaticality judgment task. At normal speech rate, all children had near-perfect performance. When the speech signal was compressed to 50% of its original rate, to…

Integrating models to predict regional haze from wildland fire.

Treesearch

D. McKenzie; S.M. O' Neill; N. Larkin; R.A. Norheim

2006-01-01

Visibility impairment from regional haze is a significant problem throughout the continental United States. A substantial portion of regional haze is produced by smoke from prescribed and wildland fires. Here we describe the integration of four simulation models, an array of GIS raster layers, and a set of algorithms for fire-danger calculations into a modeling...

Impaired Oral Reading in Two Atypical Dyslexics: A Comparison with a Computational Lexical-Analogy Model

ERIC Educational Resources Information Center

Marchand, Y.; Friedman, R.B.

2005-01-01

A computational model of reading was developed based upon the notion that the structural relationship between orthography and phonology is of greater importance than the dimension of semantics for the reading aloud of single words. Degradation of this model successfully simulated the reading performance of two patients with atypical acquired…

Sport simulation as a form of implicit motor training in a geriatric athlete after stroke: a case report.

PubMed

Young, Sonia N; VanWye, William R; Wallmann, Harvey W

2018-06-25

To describe the use of sport simulation activities as a form of implicit motor learning training with a geriatric former athlete following a stroke. An active 76-year-old former professional male softball player presented to outpatient physical therapy with medical history of right stroke with left hemiparesis 2 weeks following onset of symptoms of impaired balance, coordination, gait, and motor planning. Initial physical therapy included gait, balance, and coordination training. Additional sport-related balance and coordination activities were later added to the treatment plan. After approximately 3 weeks of treatment, the patient was able to return to work and had dramatically improved balance, coordination, and gait with sport simulation activities. Implicit motor learning techniques were incorporated through sport and job task simulation activities along with task-oriented neuromuscular reeducation. The patient demonstrated improvements with gait, balance, gross motor function, and decreased fall risk.

COLLISION AVOIDANCE TRAINING USING A DRIVING SIMULATOR IN DRIVERS WITH PARKINSON’S DISEASE: A PILOT STUDY

PubMed Central

Dawson, Jeffrey D.; Rizzo, Matthew; Anderson, Steven W.; Dastrup, Elizabeth; Uc, Ergun Y.

2011-01-01

Summary Parkinson’s disease (PD) impairs driving performance, and simulator studies have shown increased crashes compared to controls. In this pilot study, eight drivers with PD participated in three drive sessions with multiple simulator intersections of varying visibility and traffic load, where an incurring vehicle posed a crash risk. Over the course of the three sessions (once every 1–2 weeks), we observed reduction in crashes (p=0.059) and reaction times (p=0.006) to the vehicle incursion. These findings suggest that our simulator training program is feasible and potentially useful in drivers with PD. Future research questions include transfer of training to different driving tasks, duration of benefit, and the effect on long term real life outcomes in comparison to a standard intervention (e.g., driver education class) in a randomized trial. PMID:24273752

Aquatic organism passage at road-stream crossings—synthesis and guidelines for effectiveness monitoring

USGS Publications Warehouse

Hoffman, Robert L.; Dunham, Jason B.; Hansen, Bruce P.

2012-01-01

Restoration and maintenance of passage for aquatic organisms at road-stream crossings represents a major management priority, involving an investment of hundreds of millions of dollars (for example, U.S. Government Accounting Office, 2001). In recent years, passage at hundreds of crossings has been restored, primarily by replacing barrier road culverts with bridges or stream simulation culverts designed to pass all species and all life stages of aquatic life and simulate natural hydro-geomorphic processes (U.S. Forest Service, 2008). The current situation has motivated two general questions: 1. Are current design standards for stream simulation culverts adequately re-establishing passage for aquatic biota? and 2. How do we monitor and evaluate effectiveness of passage restoration? To address the latter question, a national workshop was held in March 2010, in Portland, Oregon. The workshop included experts on aquatic organism passage from across the nation (see table of participants, APPENDIX) who addressed four classes of methods for monitoring effectiveness of aquatic organism passage—individual movement, occupancy, demography, and genetics. This report has been written, in part, for field biologists who will be undertaking and evaluating the effectiveness of aquatic organism passage restoration projects at road-stream crossings. The report outlines basic methods for evaluating road-stream crossing passage impairment and restoration and discusses under what circumstances and conditions each method will be useful; what questions each method can potentially answer; how to design and implement an evaluation study; and points out the fundamental reality that most evaluation projects will require special funding and partnerships among researchers and resource managers. The report is organized into the following sections, which can be read independently: 1. Historical context: In this section, we provide a brief history of events leading up to the present situation involving aquatic organism passage as a useful context for the issues covered herein. 2. Importance of connectivity for aquatic organisms: In this section, we provide background information regarding the movement characteristics of aquatic organisms and their vulnerability to passage impairment, and the importance of connectivity for a broad diversity of aquatic vertebrates and invertebrates. This section should be useful for practitioners in selecting what species to monitor in relation to aquatic organism passage. 3. Methods for evaluating aquatic organism passage: In this section, we present a range of perspectives on alternatives for assessing and monitoring aquatic organism passage impairment and the effectiveness of passage restoration actions, including the following methods: Individual Movement, Occupancy Models, Abundance (Demography), and Molecular Genetic Markers. 4. Relevance, strengths, and limitations of the four methods: In this section, we discuss the utility of each of the methods as a tool for assessing and quantifying passage impairment and restoration effectiveness. 5. Guidelines for selecting a method: In this section, we review some fundamental criteria and guidelines to consider when selecting a method for monitoring in the context of answering three important questions that should be addressed when developing a plan for evaluating aquatic organism passage. 6. Study and monitoring design considerations: In this section, we discuss four key design elements that need to be considered when developing a monitoring design for assessing passage impairment and restoration. The basic objectives of the report are to: 1. Review the movement characteristics of five groups of aquatic organisms that inhabit streams and to assess their general vulnerability to passage impairment at road-stream crossings; 2. Review four methods for monitoring aquatic organism passage impairment and the effectiveness of actions to restore passage at road-stream crossing structures; 3. Assess the relevance, strengths, and limitations of each method as a monitoring tool; 4. Identify and discuss guidelines that will be useful for selecting a monitoring method; and 5. Discuss what we have identified as the four key elements that need to be considered when developing a monitoring design for assessing passage impairment and restoration at road-stream crossings.

Ergodicity and model quality in template-restrained canonical and temperature/Hamiltonian replica exchange coarse-grained molecular dynamics simulations of proteins.

PubMed

Karczyńska, Agnieszka S; Czaplewski, Cezary; Krupa, Paweł; Mozolewska, Magdalena A; Joo, Keehyoung; Lee, Jooyoung; Liwo, Adam

2017-12-05

Molecular simulations restrained to single or multiple templates are commonly used in protein-structure modeling. However, the restraints introduce additional barriers, thus impairing the ergodicity of simulations, which can affect the quality of the resulting models. In this work, the effect of restraint types and simulation schemes on ergodicity and model quality was investigated by performing template-restrained canonical molecular dynamics (MD), multiplexed replica-exchange molecular dynamics, and Hamiltonian replica exchange molecular dynamics (HREMD) simulations with the coarse-grained UNRES force field on nine selected proteins, with pseudo-harmonic log-Gaussian (unbounded) or Lorentzian (bounded) restraint functions. The best ergodicity was exhibited by HREMD. It has been found that non-ergodicity does not affect model quality if good templates are used to generate restraints. However, when poor-quality restraints not covering the entire protein are used, the improved ergodicity of HREMD can lead to significantly improved protein models. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Real-time software-based end-to-end wireless visual communications simulation platform

NASA Astrophysics Data System (ADS)

Chen, Ting-Chung; Chang, Li-Fung; Wong, Andria H.; Sun, Ming-Ting; Hsing, T. Russell

1995-04-01

Wireless channel impairments pose many challenges to real-time visual communications. In this paper, we describe a real-time software based wireless visual communications simulation platform which can be used for performance evaluation in real-time. This simulation platform consists of two personal computers serving as hosts. Major components of each PC host include a real-time programmable video code, a wireless channel simulator, and a network interface for data transport between the two hosts. The three major components are interfaced in real-time to show the interaction of various wireless channels and video coding algorithms. The programmable features in the above components allow users to do performance evaluation of user-controlled wireless channel effects without physically carrying out these experiments which are limited in scope, time-consuming, and costly. Using this simulation platform as a testbed, we have experimented with several wireless channel effects including Rayleigh fading, antenna diversity, channel filtering, symbol timing, modulation, and packet loss.

Speech perception benefits of internet versus conventional telephony for hearing-impaired individuals.

PubMed

Mantokoudis, Georgios; Dubach, Patrick; Pfiffner, Flurin; Kompis, Martin; Caversaccio, Marco; Senn, Pascal

2012-07-16

Telephone communication is a challenge for many hearing-impaired individuals. One important technical reason for this difficulty is the restricted frequency range (0.3-3.4 kHz) of conventional landline telephones. Internet telephony (voice over Internet protocol [VoIP]) is transmitted with a larger frequency range (0.1-8 kHz) and therefore includes more frequencies relevant to speech perception. According to a recently published, laboratory-based study, the theoretical advantage of ideal VoIP conditions over conventional telephone quality has translated into improved speech perception by hearing-impaired individuals. However, the speech perception benefits of nonideal VoIP network conditions, which may occur in daily life, have not been explored. VoIP use cannot be recommended to hearing-impaired individuals before its potential under more realistic conditions has been examined. To compare realistic VoIP network conditions, under which digital data packets may be lost, with ideal conventional telephone quality with respect to their impact on speech perception by hearing-impaired individuals. We assessed speech perception using standardized test material presented under simulated VoIP conditions with increasing digital data packet loss (from 0% to 20%) and compared with simulated ideal conventional telephone quality. We monaurally tested 10 adult users of cochlear implants, 10 adult users of hearing aids, and 10 normal-hearing adults in the free sound field, both in quiet and with background noise. Across all participant groups, mean speech perception scores using VoIP with 0%, 5%, and 10% packet loss were 15.2% (range 0%-53%), 10.6% (4%-46%), and 8.8% (7%-33%) higher, respectively, than with ideal conventional telephone quality. Speech perception did not differ between VoIP with 20% packet loss and conventional telephone quality. The maximum benefits were observed under ideal VoIP conditions without packet loss and were 36% (P = .001) for cochlear implant users, 18% (P = .002) for hearing aid users, and 53% (P = .001) for normal-hearing adults. With a packet loss of 10%, the maximum benefits were 30% (P = .002) for cochlear implant users, 6% (P = .38) for hearing aid users, and 33% (P = .002) for normal-hearing adults. VoIP offers a speech perception benefit over conventional telephone quality, even when mild or moderate packet loss scenarios are created in the laboratory. VoIP, therefore, has the potential to significantly improve telecommunication abilities for the large community of hearing-impaired individuals.

Speech Perception Benefits of Internet Versus Conventional Telephony for Hearing-Impaired Individuals

PubMed Central

Dubach, Patrick; Pfiffner, Flurin; Kompis, Martin; Caversaccio, Marco

2012-01-01

Background Telephone communication is a challenge for many hearing-impaired individuals. One important technical reason for this difficulty is the restricted frequency range (0.3–3.4 kHz) of conventional landline telephones. Internet telephony (voice over Internet protocol [VoIP]) is transmitted with a larger frequency range (0.1–8 kHz) and therefore includes more frequencies relevant to speech perception. According to a recently published, laboratory-based study, the theoretical advantage of ideal VoIP conditions over conventional telephone quality has translated into improved speech perception by hearing-impaired individuals. However, the speech perception benefits of nonideal VoIP network conditions, which may occur in daily life, have not been explored. VoIP use cannot be recommended to hearing-impaired individuals before its potential under more realistic conditions has been examined. Objective To compare realistic VoIP network conditions, under which digital data packets may be lost, with ideal conventional telephone quality with respect to their impact on speech perception by hearing-impaired individuals. Methods We assessed speech perception using standardized test material presented under simulated VoIP conditions with increasing digital data packet loss (from 0% to 20%) and compared with simulated ideal conventional telephone quality. We monaurally tested 10 adult users of cochlear implants, 10 adult users of hearing aids, and 10 normal-hearing adults in the free sound field, both in quiet and with background noise. Results Across all participant groups, mean speech perception scores using VoIP with 0%, 5%, and 10% packet loss were 15.2% (range 0%–53%), 10.6% (4%–46%), and 8.8% (7%–33%) higher, respectively, than with ideal conventional telephone quality. Speech perception did not differ between VoIP with 20% packet loss and conventional telephone quality. The maximum benefits were observed under ideal VoIP conditions without packet loss and were 36% (P = .001) for cochlear implant users, 18% (P = .002) for hearing aid users, and 53% (P = .001) for normal-hearing adults. With a packet loss of 10%, the maximum benefits were 30% (P = .002) for cochlear implant users, 6% (P = .38) for hearing aid users, and 33% (P = .002) for normal-hearing adults. Conclusions VoIP offers a speech perception benefit over conventional telephone quality, even when mild or moderate packet loss scenarios are created in the laboratory. VoIP, therefore, has the potential to significantly improve telecommunication abilities for the large community of hearing-impaired individuals. PMID:22805169

Visual noise disrupts conceptual integration in reading.

PubMed

Gao, Xuefei; Stine-Morrow, Elizabeth A L; Noh, Soo Rim; Eskew, Rhea T

2011-02-01

The Effortfulness Hypothesis suggests that sensory impairment (either simulated or age-related) may decrease capacity for semantic integration in language comprehension. We directly tested this hypothesis by measuring resource allocation to different levels of processing during reading (i.e., word vs. semantic analysis). College students read three sets of passages word-by-word, one at each of three levels of dynamic visual noise. There was a reliable interaction between processing level and noise, such that visual noise increased resources allocated to word-level processing, at the cost of attention paid to semantic analysis. Recall of the most important ideas also decreased with increasing visual noise. Results suggest that sensory challenge can impair higher-level cognitive functions in learning from text, supporting the Effortfulness Hypothesis.

SOCIAL AND NON-SOCIAL HAZARD RESPONSE IN DRIVERS WITH AUTISM SPECTRUM DISORDER

PubMed Central

Bishop, Haley Johnson; Biasini, Fred J.; Stavrinos, Despina

2017-01-01

Driving is a complex task that relies on manual, cognitive, visual and social skill. The social demands of driving may be challenging for individuals with Autism Spectrum Disorder (ASD) due to known social impairments. This study investigated how drivers with ASD respond to social (e.g., pedestrians) and non-social (e.g., vehicles) hazards in a driving simulator compared to typically developing drivers. Overall, participants responded faster to social hazards than non-social hazards. It was also found that drivers with typical development reacted faster to social hazards, while drivers with ASD showed no difference in reaction time to social versus non-social hazards. Future work should further investigate how social impairments in ASD may affect driving safety. PMID:28070791

Simulated visual field loss does not alter turning coordination in healthy young adults.

PubMed

Murray, Nicholas G; Ponce de Leon, Marlina; Ambati, V N Pradeep; Saucedo, Fabricio; Kennedy, Evan; Reed-Jones, Rebecca J

2014-01-01

Turning, while walking, is an important component of adaptive locomotion. Current hypotheses regarding the motor control of body segment coordination during turning suggest heavy influence of visual information. The authors aimed to examine whether visual field impairment (central loss or peripheral loss) affects body segment coordination during walking turns in healthy young adults. No significant differences in the onset time of segments or intersegment coordination were observed because of visual field occlusion. These results suggest that healthy young adults can use visual information obtained from central and peripheral visual fields interchangeably, pointing to flexibility of visuomotor control in healthy young adults. Further study in populations with chronic visual impairment and those with turning difficulties are warranted.

Sentence Recognition Prediction for Hearing-impaired Listeners in Stationary and Fluctuation Noise With FADE: Empowering the Attenuation and Distortion Concept by Plomp With a Quantitative Processing Model.

PubMed

Kollmeier, Birger; Schädler, Marc René; Warzybok, Anna; Meyer, Bernd T; Brand, Thomas

2016-09-07

To characterize the individual patient's hearing impairment as obtained with the matrix sentence recognition test, a simulation Framework for Auditory Discrimination Experiments (FADE) is extended here using the Attenuation and Distortion (A+D) approach by Plomp as a blueprint for setting the individual processing parameters. FADE has been shown to predict the outcome of both speech recognition tests and psychoacoustic experiments based on simulations using an automatic speech recognition system requiring only few assumptions. It builds on the closed-set matrix sentence recognition test which is advantageous for testing individual speech recognition in a way comparable across languages. Individual predictions of speech recognition thresholds in stationary and in fluctuating noise were derived using the audiogram and an estimate of the internal level uncertainty for modeling the individual Plomp curves fitted to the data with the Attenuation (A-) and Distortion (D-) parameters of the Plomp approach. The "typical" audiogram shapes from Bisgaard et al with or without a "typical" level uncertainty and the individual data were used for individual predictions. As a result, the individualization of the level uncertainty was found to be more important than the exact shape of the individual audiogram to accurately model the outcome of the German Matrix test in stationary or fluctuating noise for listeners with hearing impairment. The prediction accuracy of the individualized approach also outperforms the (modified) Speech Intelligibility Index approach which is based on the individual threshold data only. © The Author(s) 2016.

Brain drain? An examination of stereotype threat effects during training on knowledge acquisition and organizational effectiveness.

PubMed

Grand, James A

2017-02-01

Stereotype threat describes a situation in which individuals are faced with the risk of upholding a negative stereotype about their subgroup based on their actions. Empirical work in this area has primarily examined the impact of negative stereotypes on performance for threatened individuals. However, this body of research seldom acknowledges that performance is a function of learning-which may also be impaired by pervasive group stereotypes. This study presents evidence from a 3-day self-guided training program demonstrating that stereotype threat impairs acquisition of cognitive learning outcomes for females facing a negative group stereotype. Using hierarchical Bayesian modeling, results revealed that stereotyped females demonstrated poorer declarative knowledge acquisition, spent less time reflecting on learning activities, and developed less efficiently organized knowledge structures compared with females in a control condition. Findings from a Bayesian mediation model also suggested that despite stereotyped individuals "working harder" to perform well, their underachievement was largely attributable to failures in learning to "work smarter." Building upon these empirical results, a computational model and computer simulation is also presented to demonstrate the practical significance of stereotype-induced impairments to learning on the development of an organization's human capital resources and capabilities. The simulation results show that even the presence of small effects of stereotype threat during learning/training have the potential to exert a significant negative impact on an organization's performance potential. Implications for future research and practice examining stereotype threat during learning are discussed. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Effects of headset, flight workload, hearing ability, and communications message quality on pilot performance.

PubMed

Casto, Kristen L; Casali, John G

2013-06-01

This study was designed to determine the effects of hearing loss, aviation headset type, flight workload complexity, and communication signal quality on pilots' performance in an army rotary-wing flight simulator. To maintain flight status, army aviators who do not meet current audiometric standards require a hearing loss waiver, which is based on speech intelligibility in quiet conditions. Because hearing loss characteristics of hearing-impaired aviators can vary greatly, and because performance is likely also influenced by degree of flight workload and communication demand, it was expected that performance among hearing-impaired aviators would also vary. Participants were 20 army helicopter pilots. Pilots flew three flights in a full motion-based helicopter simulator,with a different headset configuration and varying flight workload levels and communication signal quality characterizing each flight. Objective flight performance parameters of heading, altitude, and airspeed deviation and air traffic control command read-backs were measured. Statistically significant results suggest that high levels of flight workload, especially in combination with poor communications signal quality, lead to deficits in flight performance and speech intelligibility. These results support a conclusion that factors other than hearing thresholds and speech intelligibility in quiet should be considered when evaluating helicopter pilots' flight safety. The results also support a recommendation that hearing-impaired pilots use assistive communication technology and not fly with strictly passive headsets. The combined effects of flight environment with individual hearing levels should be considered when making recommendations concerning continued aviation flight status and those concerning communications headsets used in high-noise cockpits.

Impact of distraction on the driving performance of adolescents with and without attention-deficit/hyperactivity disorder.

PubMed

Narad, Megan; Garner, Annie A; Brassell, Anne A; Saxby, Dyani; Antonini, Tanya N; O'Brien, Kathleen M; Tamm, Leanne; Matthews, Gerald; Epstein, Jeffery N

2013-10-01

This study extends the literature regarding attention-deficit/hyperactivity disorder (ADHD)-related driving impairments to a newly licensed, adolescent population. To investigate the combined risks of adolescence, ADHD, and distracted driving (cell phone conversation and text messaging) on driving performance. Adolescents aged 16 to 17 years with (n = 28) and without (n = 33) ADHD engaged in a simulated drive under 3 conditions (no distraction, cell phone conversation, and texting). During each condition, one unexpected event (eg, another car suddenly merging into driver's lane) was introduced. Cell phone conversation, texting, and no distraction while driving. Self-report of driving history, average speed, standard deviation of speed, standard deviation of lateral position, and braking reaction time during driving simulation. Adolescents with ADHD reported fewer months of driving experience and a higher proportion of driving violations than control subjects. After controlling for months of driving history, adolescents with ADHD demonstrated more variability in speed and lane position than control subjects. There were no group differences for braking reaction time. Furthermore, texting negatively impacted the driving performance of all participants as evidenced by increased variability in speed and lane position. To our knowledge, this study is one of the first to investigate distracted driving in adolescents with ADHD and adds to a growing body of literature documenting that individuals with ADHD are at increased risk for negative driving outcomes. Furthermore, texting significantly impairs the driving performance of all adolescents and increases existing driving-related impairment in adolescents with ADHD, highlighting the need for education and enforcement of regulations against texting for this age group.

Investigating cognitive ability and self-reported driving performance of post-stroke adults in a driving simulator.

PubMed

Blane, Alison; Falkmer, Torbjörn; Lee, Hoe C; Dukic Willstrand, Tania

2018-01-01

Background Safe driving is a complex activity that requires calibration. This means the driver can accurately assess the level of task demand required for task completion and can accurately evaluate their driving capability. There is much debate on the calibration ability of post-stroke drivers. Objectives The aim of this study was to assess the cognition, self-rated performance, and estimation of task demand in a driving simulator with post-stroke drivers and controls. Methods A between-groups study design was employed, which included a post-stroke driver group and a group of similarly aged older control drivers. Both groups were observed driving in two simulator-based driving scenarios and asked to complete the NASA Task Load Index (TLX) to assess their perceived task demand and self-rate their driving performance. Participants also completed a battery of psychometric tasks to assess attention and executive function, which was used to determine whether post-stroke cognitive impairment impacted on calibration. Results There was no difference in the amount of perceived task demand required to complete the driving task. Despite impairments in cognition, the post-stroke drivers were not more likely to over-estimate their driving abilities than controls. On average, the post-stroke drivers self-rated themselves more poorly than the controls and this rating was related to cognitive ability. Conclusion This study suggests that post-stroke drivers may be aware of their deficits and adjust their driving behavior. Furthermore, using self-performance measures alongside a driving simulator and cognitive assessments may provide complementary fitness-to-drive assessments, as well as rehabilitation tools during post-stroke recovery.

The Integrated Medical Model: A Probabilistic Simulation Model for Predicting In-Flight Medical Risks

NASA Technical Reports Server (NTRS)

Keenan, Alexandra; Young, Millennia; Saile, Lynn; Boley, Lynn; Walton, Marlei; Kerstman, Eric; Shah, Ronak; Goodenow, Debra A.; Myers, Jerry G.

2015-01-01

The Integrated Medical Model (IMM) is a probabilistic model that uses simulation to predict mission medical risk. Given a specific mission and crew scenario, medical events are simulated using Monte Carlo methodology to provide estimates of resource utilization, probability of evacuation, probability of loss of crew, and the amount of mission time lost due to illness. Mission and crew scenarios are defined by mission length, extravehicular activity (EVA) schedule, and crew characteristics including: sex, coronary artery calcium score, contacts, dental crowns, history of abdominal surgery, and EVA eligibility. The Integrated Medical Evidence Database (iMED) houses the model inputs for one hundred medical conditions using in-flight, analog, and terrestrial medical data. Inputs include incidence, event durations, resource utilization, and crew functional impairment. Severity of conditions is addressed by defining statistical distributions on the dichotomized best and worst-case scenarios for each condition. The outcome distributions for conditions are bounded by the treatment extremes of the fully treated scenario in which all required resources are available and the untreated scenario in which no required resources are available. Upon occurrence of a simulated medical event, treatment availability is assessed, and outcomes are generated depending on the status of the affected crewmember at the time of onset, including any pre-existing functional impairments or ongoing treatment of concurrent conditions. The main IMM outcomes, including probability of evacuation and loss of crew life, time lost due to medical events, and resource utilization, are useful in informing mission planning decisions. To date, the IMM has been used to assess mission-specific risks with and without certain crewmember characteristics, to determine the impact of eliminating certain resources from the mission medical kit, and to design medical kits that maximally benefit crew health while meeting mass and volume constraints.

The Integrated Medical Model: A Probabilistic Simulation Model Predicting In-Flight Medical Risks

NASA Technical Reports Server (NTRS)

Keenan, Alexandra; Young, Millennia; Saile, Lynn; Boley, Lynn; Walton, Marlei; Kerstman, Eric; Shah, Ronak; Goodenow, Debra A.; Myers, Jerry G., Jr.

2015-01-01

The Integrated Medical Model (IMM) is a probabilistic model that uses simulation to predict mission medical risk. Given a specific mission and crew scenario, medical events are simulated using Monte Carlo methodology to provide estimates of resource utilization, probability of evacuation, probability of loss of crew, and the amount of mission time lost due to illness. Mission and crew scenarios are defined by mission length, extravehicular activity (EVA) schedule, and crew characteristics including: sex, coronary artery calcium score, contacts, dental crowns, history of abdominal surgery, and EVA eligibility. The Integrated Medical Evidence Database (iMED) houses the model inputs for one hundred medical conditions using in-flight, analog, and terrestrial medical data. Inputs include incidence, event durations, resource utilization, and crew functional impairment. Severity of conditions is addressed by defining statistical distributions on the dichotomized best and worst-case scenarios for each condition. The outcome distributions for conditions are bounded by the treatment extremes of the fully treated scenario in which all required resources are available and the untreated scenario in which no required resources are available. Upon occurrence of a simulated medical event, treatment availability is assessed, and outcomes are generated depending on the status of the affected crewmember at the time of onset, including any pre-existing functional impairments or ongoing treatment of concurrent conditions. The main IMM outcomes, including probability of evacuation and loss of crew life, time lost due to medical events, and resource utilization, are useful in informing mission planning decisions. To date, the IMM has been used to assess mission-specific risks with and without certain crewmember characteristics, to determine the impact of eliminating certain resources from the mission medical kit, and to design medical kits that maximally benefit crew health while meeting mass and volume constraints.

Alteration of infant attention and activity by polychlorinated biphenyls: unravelling critical windows of susceptibility using physiologically based pharmacokinetic modeling.

PubMed

Verner, M-A; Plusquellec, P; Muckle, G; Ayotte, P; Dewailly, E; Jacobson, S W; Jacobson, J L; Charbonneau, M; Haddad, S

2010-09-01

Pre- and postnatal exposure to polychlorinated biphenyls (PCBs) can impair behavioural function in animal models at doses within the range at which humans are commonly exposed. Yet, epidemiologic studies conducted in the US and Europe are inconsistent with regard to the developmental effects of lactational exposure to these chemicals. This inconsistency may be due to limitations in the current methodological approaches for assessing postnatal exposure to PCBs. Our study used a physiologically based pharmacokinetic (PBPK) model to simulate blood PCB levels during specific pre- and postnatal periods and to evaluate the relation of those levels to infant behaviour. A previously validated PBPK model was used to simulate infant blood PCB-153 levels at delivery and on a month-by-month basis during the first year of life for Inuit infants enrolled in a longitudinal birth cohort. Infant behaviour was assessed using the Behaviour Rating Scales (BRS) of the Bayley Scales of Infant Development (BSID-II) at 11 months of age and video coding of inattention and activity measured during the administration of the mental development subscale of the BSID-II. The estimated pre- and postnatal PCB exposure measures predicted significant increases in inattention and activity at 11 months. Whereas inattention was related to prenatal exposure, activity level, measured by non-elicited activity, was best predicted by postnatal exposure, with the strongest association obtained for simulated PCB levels during the 4th month of life. These findings are consistent with previous reports indicating PCB-induced behavioural alteration in attention and activity level. Simulated infant toxicokinetic profiles for the first year of life revealed windows of susceptibility during which PCBs may impair infant attention and activity. Copyright © 2010 Elsevier Inc. All rights reserved.

MEchatronic REspiratory System SImulator for Neonatal Applications (MERESSINA) project: a novel bioengineering goal

PubMed Central

Scaramuzzo, Rosa T; Ciantelli, Massimiliano; Baldoli, Ilaria; Bellanti, Lisa; Gentile, Marzia; Cecchi, Francesca; Sigali, Emilio; Tognarelli, Selene; Ghirri, Paolo; Mazzoleni, Stefano; Menciassi, Arianna; Cuttano, Armando; Boldrini, Antonio; Laschi, Cecilia; Dario, Paolo

2013-01-01

Respiratory function is mandatory for extrauterine life, but is sometimes impaired in newborns due to prematurity, congenital malformations, or acquired pathologies. Mechanical ventilation is standard care, but long-term complications, such as bronchopulmonary dysplasia, are still largely reported. Therefore, continuous medical education is mandatory to correctly manage devices for assistance. Commercially available breathing function simulators are rarely suitable for the anatomical and physiological realities. The aim of this study is to develop a high-fidelity mechatronic simulator of neonatal airways and lungs for staff training and mechanical ventilator testing. The project is divided into three different phases: (1) a review study on respiratory physiology and pathophysiology and on already available single and multi-compartment models; (2) the prototyping phase; and (3) the on-field system validation. PMID:23966804

Impairment due to combined sleep restriction and alcohol is not mitigated by decaying breath alcohol concentration or rest breaks.

PubMed

Manousakis, Jessica E; Anderson, Clare

2017-09-01

Epidemiological and laboratory-based driving simulator studies have shown the detrimental impact of moderate, legal levels of alcohol consumption on driving performance in sleepy drivers. As less is known about the time course of decaying alcohol alongside performance impairment, our study examined impairment and recovery of performance alongside decaying levels of alcohol, with and without sleep restriction. Sixteen healthy young males (18-27 years) underwent 4 counterbalanced conditions: Baseline, Alcohol (breath alcohol concentration [BrAC] < 0.05%), Sleep Restriction (5 hr time in bed), and Combined. Participants consumed alcohol (or control drink) ~4.5 hr post wake (12:30 p.m.). To test on the descending limb of alcohol, attention and vigilance test batteries commenced 1 hr after consumption and were completed every 30 min for 2 hr (1:30 p.m.-3:30 p.m.). The Combined condition impaired subjective and objective sleepiness. Here, performance deficits peaked 90 min after alcohol consumption or 30 min after the BrAC peak. Performance did not return to baseline levels until 2.5 hr following consumption, despite receiving rest breaks in between testing. These findings suggest that (a) falling BrACs are an inadequate guide for performance/safety and (b) rest breaks without sleep are not a safety measure for mitigating performance impairment when consuming alcohol following restricted sleep. Copyright © 2017 John Wiley & Sons, Ltd.

Phenylethanoid glycosides of Pedicularis muscicola Maxim ameliorate high altitude-induced memory impairment.

PubMed

Zhou, Baozhu; Li, Maoxing; Cao, Xinyuan; Zhang, Quanlong; Liu, Yantong; Ma, Qiang; Qiu, Yan; Luan, Fei; Wang, Xianmin

2016-04-01

Exposure to hypobaric hypoxia causes oxidative stress, neuronal degeneration and apoptosis that leads to memory impairment. Though oxidative stress contributes to neuronal degeneration and apoptosis in hypobaric hypoxia, the ability for phenylethanoid glycosides of Pedicularis muscicola Maxim (PhGs) to reverse high altitude memory impairment has not been studied. Rats were supplemented with PhGs orally for a week. After the fourth day of drug administration, rats were exposed to a 7500 m altitude simulation in a specially designed animal decompression chamber for 3 days. Spatial memory was assessed by the 8-arm radial maze test before and after exposure to hypobaric hypoxia. Histological assessment of neuronal degeneration was performed by hematoxylin-eosin (HE) staining. Changes in oxidative stress markers and changes in the expression of the apoptotic marker, caspase-3, were assessed in the hippocampus. Our results demonstrated that after exposure to hypobaric hypoxia, PhGs ameliorated high altitude memory impairment, as shown by the decreased values obtained for reference memory error (RME), working memory error (WME), and total error (TE). Meanwhile, administration of PhGs decreased hippocampal reactive oxygen species levels and consequent lipid peroxidation by elevating reduced glutathione levels and enhancing the free radical scavenging enzyme system. There was also a decrease in the number of pyknotic neurons and a reduction in caspase-3 expression in the hippocampus. These findings suggest that PhGs may be used therapeutically to ameliorate high altitude memory impairment. Copyright © 2016 Elsevier Inc. All rights reserved.

Counterfactual Thinking Deficit in Huntington’s Disease

PubMed Central

Solca, Federica; Poletti, Barbara; Zago, Stefano; Crespi, Chiara; Sassone, Francesca; Lafronza, Annalisa; Maraschi, Anna Maria; Sassone, Jenny; Silani, Vincenzo; Ciammola, Andrea

2015-01-01

Background and Objective Counterfactual thinking (CFT) refers to the generation of mental simulations of alternatives to past events, actions and outcomes. CFT is a pervasive cognitive feature in every-day life and is closely related to decision-making, planning and problem-solving – all of which are cognitive processes linked to unimpaired frontal lobe functioning. Huntington’s Disease (HD) is a neurodegenerative disorder characterised by motor, behavioral and cognitive dysfunctions. Because an impairment in frontal and executive functions has been described in HD, we hypothesised that HD patients may have a CFT impairment. Methods Tests of spontaneous counterfactual thoughts and counterfactual-derived inferences were administered to 24 symptomatic HD patients and 24 age- and sex-matched healthy subjects. Results Our results show a significant impairment in the spontaneous generation of CFT and low performance on the Counterfactual Inference Test (CIT) in HD patients. Low performance on the spontaneous CFT test significantly correlates with impaired attention abilities, verbal fluency and frontal lobe efficiency, as measured by Trail Making Test – Part A, Phonemic Verbal Fluency Test and FAB. Conclusions Spontaneous CFT and the use of this type of reasoning are impaired in HD patients. This deficit may be related to frontal lobe dysfunction, which is a hallmark of HD. Because CFT has a pervasive role in patients’ daily lives regarding their planning, decision making and problem solving skills, cognitive rehabilitation may improve HD patients’ ability to analyse current behaviors and future actions. PMID:26070155

Sensitivity to Angular and Radial Source Movements as a Function of Acoustic Complexity in Normal and Impaired Hearing

PubMed Central

Grimm, Giso; Hohmann, Volker; Laugesen, Søren; Neher, Tobias

2017-01-01

In contrast to static sounds, spatially dynamic sounds have received little attention in psychoacoustic research so far. This holds true especially for acoustically complex (reverberant, multisource) conditions and impaired hearing. The current study therefore investigated the influence of reverberation and the number of concurrent sound sources on source movement detection in young normal-hearing (YNH) and elderly hearing-impaired (EHI) listeners. A listening environment based on natural environmental sounds was simulated using virtual acoustics and rendered over headphones. Both near-far (‘radial’) and left-right (‘angular’) movements of a frontal target source were considered. The acoustic complexity was varied by adding static lateral distractor sound sources as well as reverberation. Acoustic analyses confirmed the expected changes in stimulus features that are thought to underlie radial and angular source movements under anechoic conditions and suggested a special role of monaural spectral changes under reverberant conditions. Analyses of the detection thresholds showed that, with the exception of the single-source scenarios, the EHI group was less sensitive to source movements than the YNH group, despite adequate stimulus audibility. Adding static sound sources clearly impaired the detectability of angular source movements for the EHI (but not the YNH) group. Reverberation, on the other hand, clearly impaired radial source movement detection for the EHI (but not the YNH) listeners. These results illustrate the feasibility of studying factors related to auditory movement perception with the help of the developed test setup. PMID:28675088

Sensitivity to Angular and Radial Source Movements as a Function of Acoustic Complexity in Normal and Impaired Hearing.

PubMed

Lundbeck, Micha; Grimm, Giso; Hohmann, Volker; Laugesen, Søren; Neher, Tobias

2017-01-01

In contrast to static sounds, spatially dynamic sounds have received little attention in psychoacoustic research so far. This holds true especially for acoustically complex (reverberant, multisource) conditions and impaired hearing. The current study therefore investigated the influence of reverberation and the number of concurrent sound sources on source movement detection in young normal-hearing (YNH) and elderly hearing-impaired (EHI) listeners. A listening environment based on natural environmental sounds was simulated using virtual acoustics and rendered over headphones. Both near-far ('radial') and left-right ('angular') movements of a frontal target source were considered. The acoustic complexity was varied by adding static lateral distractor sound sources as well as reverberation. Acoustic analyses confirmed the expected changes in stimulus features that are thought to underlie radial and angular source movements under anechoic conditions and suggested a special role of monaural spectral changes under reverberant conditions. Analyses of the detection thresholds showed that, with the exception of the single-source scenarios, the EHI group was less sensitive to source movements than the YNH group, despite adequate stimulus audibility. Adding static sound sources clearly impaired the detectability of angular source movements for the EHI (but not the YNH) group. Reverberation, on the other hand, clearly impaired radial source movement detection for the EHI (but not the YNH) listeners. These results illustrate the feasibility of studying factors related to auditory movement perception with the help of the developed test setup.

The Structural Basis of Oncogenic Mutations G12, G13 and Q61 in Small GTPase K-Ras4B

NASA Astrophysics Data System (ADS)

Lu, Shaoyong; Jang, Hyunbum; Nussinov, Ruth; Zhang, Jian

2016-02-01

Ras mediates cell proliferation, survival and differentiation. Mutations in K-Ras4B are predominant at residues G12, G13 and Q61. Even though all impair GAP-assisted GTP → GDP hydrolysis, the mutation frequencies of K-Ras4B in human cancers vary. Here we aim to figure out their mechanisms and differential oncogenicity. In total, we performed 6.4 μs molecular dynamics simulations on the wild-type K-Ras4B (K-Ras4BWT-GTP/GDP) catalytic domain, the K-Ras4BWT-GTP-GAP complex, and the mutants (K-Ras4BG12C/G12D/G12V-GTP/GDP, K-Ras4BG13D-GTP/GDP, K-Ras4BQ61H-GTP/GDP) and their complexes with GAP. In addition, we simulated ‘exchanged’ nucleotide states. These comprehensive simulations reveal that in solution K-Ras4BWT-GTP exists in two, active and inactive, conformations. Oncogenic mutations differentially elicit an inactive-to-active conformational transition in K-Ras4B-GTP; in K-Ras4BG12C/G12D-GDP they expose the bound nucleotide which facilitates the GDP-to-GTP exchange. These mechanisms may help elucidate the differential mutational statistics in K-Ras4B-driven cancers. Exchanged nucleotide simulations reveal that the conformational transition is more accessible in the GTP-to-GDP than in the GDP-to-GTP exchange. Importantly, GAP not only donates its R789 arginine finger, but stabilizes the catalytically-competent conformation and pre-organizes catalytic residue Q61; mutations disturb the R789/Q61 organization, impairing GAP-mediated GTP hydrolysis. Together, our simulations help provide a mechanistic explanation of key mutational events in one of the most oncogenic proteins in cancer.

Reagentless chemiluminescence-based fiber optic sensors for regenerative life support in space

NASA Astrophysics Data System (ADS)

Atwater, James E.; Akse, James R.; DeHart, Jeffrey; Wheeler, Richard R., Jr.

1995-04-01

The initial feasibility demonstration of a reagentless chemiluminescence based fiber optic sensor technology for use in advanced regenerative life support applications in space and planetary outposts is described. The primary constraints for extraterrestrial deployment of any technology are compatibility with microgravity and hypogravity environments; minimal size, weight, and power consumption; and minimal use of expendables due to the great expense and difficulty inherent to resupply logistics. In the current research, we report the integration of solid state flow through modules for the production of aqueous phase reagents into an integrated system for the detection of important analytes by chemiluminescence, with fiber optic light transmission. By minimizing the need for resupply expendables, the use of solid phase modules makes complex chemical detection schemes practical. For the proof of concept, hydrogen peroxide and glucose were chosen as analytes. The reaction is catalyzed by glucose oxidase, an immobilized enzyme. The aqueous phase chemistry required for sensor operation is implemented using solid phase modules which adjust the pH of the influent stream, catalyze the oxidation of analyte, and provide the controlled addition of the luminophore to the flowing aqueous stream. Precise control of the pH has proven essential for the long-term sustained release of the luminophore. Electrocatalysis is achieved using a controlled potential across gold mesh and gold foil electrodes which undergo periodic polarity reversals. The development and initial characterization of performance of the reagentless fiber optic chemiluminescence sensors are presented in this paper.

Somatic maturation and the relationship between bone mineral variables and types of sports among adolescents: cross-sectional study.

PubMed

Agostinete, Ricardo Ribeiro; Ito, Igor Hideki; Kemper, Han; Pastre, Carlos Marcelo; Rodrigues-Júnior, Mário Antônio; Luiz-de-Marco, Rafael; Fernandes, Rômulo Araújo

2017-01-01

Peak height velocity (PHV) is an important maturational event during adolescence that affects skeleton size. The objective here was to compare bone variables in adolescents who practiced different types of sports, and to identify whether differences in bone variables attributed to sports practice were dependent on somatic maturation status. Cross-sectional study, São Paulo State University (UNESP). The study was composed of 93 adolescents (12 to 16.5 years old), divided into three groups: no-sport group (n = 42), soccer/basketball group (n = 26) and swimming group (n = 25). Bone mineral density and content were measured using dual-energy x-ray absorptiometry and somatic maturation was estimated through using peak height velocity. Data on training load were provided by the coaches. Adolescents whose PHV occurred at an older age presented higher bone mineral density in their upper limbs (P = 0.018). After adjustments for confounders, such as somatic maturation, the swimmers presented lower values for bone mineral density in their lower limbs, spine and whole body. Only the bone mineral density in the upper limbs was similar between the groups. There was a negative relationship between whole-body bone mineral content and the weekly training hours (β: -1563.967; 95% confidence interval, CI: -2916.484 to -211.450). The differences in bone variables attributed to sport practice occurred independently of maturation, while high training load in situations of hypogravity seemed to be related to lower bone mass in swimmers.

Human ocular torsion during parabolic flights: an analysis with scleral search coil

NASA Technical Reports Server (NTRS)

Cheung, B. S.; Money, K.; Howard, I.; Kirienko, N.; Johnson, W.; Lackner, J.; Dizio, P.; Evanoff, J.

1992-01-01

Rotation of the eyes about the visual axis is known as ocular torsion. A lateral inclination (a "roll") of the head induces ocular torsion in the opposite direction, a response known as ocular counterrolling. For six subjects, we recorded the static (head still) and dynamic (head in oscillatory roll motion) ocular torsion in normal 1 g condition and also during the microgravity and hypergravity periods of parabolic flight, using the electromagnetic scleral search coil technique. With the head still, the direction and magnitude of torsion that occurred in response to microgravity and hypergravity differed substantially from one individual to another, but there was a significant difference in torsional magnitude between the microgravity and hypergravity periods, for all static head positions including the upright position. Under normal 1 g conditions, counterrolling compensated for about 16% of (voluntary) static head roll, while dynamic counterroll was much larger, up to 36% of head roll at 0.55 Hz. With increasing frequency of head oscillation between 0.33 Hz and 0.55 Hz, the gain of counterrolling increased and there was no change in the phase relationship. The gain of dynamic counterroll (in response to voluntary head rolling) was not significantly less in hypogravity, suggesting that on the ground at these frequencies the contribution of gravity and gravity receptors to this reflex is redundant: this reflex is probably driven by the semicircular canals. In some subjects, the torsional displacement in microgravity is accompanied by micro-torsional oscillatory motion.

Comparison of the Morel Emotional Numbing Test for Posttraumatic Stress Disorder to the Word Memory Test in neuropsychological evaluations.

PubMed

Morel, Kenneth R

2008-03-01

The most commonly feigned cognitive and psychiatric disorders for survivors of traumatic injury are memory dysfunction and posttraumatic stress disorder (PTSD). The position of the National Academy of Neuropsychology is that symptom validity tests (SVTs) should be part of any comprehensive neuropsychological evaluation. In this article the Morel Emotional Numbing Test for Posttraumatic Stress Disorder (MENT), a SVT for PTSD, was compared to a SVT for memory, the Word Memory Test (WMT). Available archival data on 216 consecutive referrals for neuropsychological evaluations at the Veterans Affairs Tennessee Valley Healthcare System were reviewed. Of the total records reviewed 37 patients had been administered both the MENT and the WMT. The clinically recommended cutoff on the WMT was used as the main criterion to classify patients into two groups: simulating impairment or credible. The results indicated that the simulating impairment group had significantly more errors on the MENT than the credible group did (p <.0001). The criterion-related characteristics of the MENT in assessing response bias in relation to the WMT were confirmed Clinical and research implications of the utilization of the MENT are discussed in this study.

Objective assessment of the effects of texting while driving: a simulator study.

PubMed

Bendak, Salaheddine

2015-01-01

Recent advances in electronic communication technology led to many drivers opting to send and receive text messages while driving. This, inevitably, has a potential to distract drivers, impair driving performance and lead to crashes. This study aims to assess the risk involved in texting while driving through assessing the distraction caused and determining the change in key driving performance indicators. Twenty-one paid young male volunteers were recruited to participate in this study. Each participant drove a driving simulator on four different scenarios involving driving while texting and without texting on highways and town roads. Results showed that texting while driving led, on average, to five times more crashes than driving without texting. Due to distraction also, participants unnecessarily crossed lane boundaries and road boundaries more often while texting as compared to driving without texting. Moreover, distraction due to texting led to participants deviating their eyes off the road while texting 15 times per session, on average, more than without texting. Results demonstrated a high-risk level of distraction and clear impairment in drivers' ability to drive safely due to texting. Based on the results, practical recommendations to combat this phenomenon are given.

Simulating Memory Impairment for Child Sexual Abuse.

PubMed

Newton, Jeremy W; Hobbs, Sue D

2015-08-01

The current study investigated effects of simulated memory impairment on recall of child sexual abuse (CSA) information. A total of 144 adults were tested for memory of a written CSA scenario in which they role-played as the victim. There were four experimental groups and two testing sessions. During Session 1, participants read a CSA story and recalled it truthfully (Genuine group), omitted CSA information (Omission group), exaggerated CSA information (Commission group), or did not recall the story at all (No Rehearsal group). One week later, at Session 2, all participants were told to recount the scenario truthfully, and their memory was then tested using free recall and cued recall questions. The Session 1 manipulation affected memory accuracy during Session 2. Specifically, compared with the Genuine group's performance, the Omission, Commission, or No Rehearsal groups' performance was characterized by increased omission and commission errors and decreased reporting of correct details. Victim blame ratings (i.e., victim responsibility and provocativeness) and participant gender predicted increased error and decreased accuracy, whereas perpetrator blame ratings predicted decreased error and increased accuracy. Findings are discussed in relation to factors that may affect memory for CSA information. Copyright © 2015 John Wiley & Sons, Ltd.

Sensitivity of early-life stage golden trout to low pH and elevated aluminum

USGS Publications Warehouse

Delonay, Aaron J.; Little, Edward E.; Woodward, Daniel F.; Brumbaugh, William G.; Farag, Aïda M.; Rabeni, Charles F.

1993-01-01

Early-life-stage golden trout (Oncorhynchus aguabonita aguabonita) were exposed to acid and Al to examine the response and determine the sensitivity of a western, alpine salmonid to conditions simulating an episodic pH depression. Freshly fertilized eggs, alevins, and swim-up larvae were exposed for 7 d to one of 12 combinations of pH and Al, and surviving fish were held to 40 d post-hatch to determine the effect of exposure on subsequent survival and recovery. Golden trout are sensitive to conditions simulating episodic acidification events typically observed in the field. Significant mortality occurred when the pH of test waters was below 5.0 in the absence of Al or when pH was 5.5 in the presence of 100 μg/L total Al. Behavioral impairments were sensitive indicators of low pH and Al stress. Impaired locomotory and feeding behavior occurred at pH 5.5 without Al and at Al concentrations > 50 μg/L. In contrast, growth, RNA-to-DNA ratio, and whole-body ion concentration were relatively less sensitive indicators of sublethal acid and Al stress.

Transient cerebral hypoperfusion and hypertensive events during atrial fibrillation: a plausible mechanism for cognitive impairment

NASA Astrophysics Data System (ADS)

Anselmino, Matteo; Scarsoglio, Stefania; Saglietto, Andrea; Gaita, Fiorenzo; Ridolfi, Luca

2016-06-01

Atrial fibrillation (AF) is associated with an increased risk of dementia and cognitive decline, independent of strokes. Several mechanisms have been proposed to explain this association, but altered cerebral blood flow dynamics during AF has been poorly investigated: in particular, it is unknown how AF influences hemodynamic parameters of the distal cerebral circulation, at the arteriolar and capillary level. Two coupled lumped-parameter models (systemic and cerebrovascular circulations, respectively) were here used to simulate sinus rhythm (SR) and AF. For each simulation 5000 cardiac cycles were analyzed and cerebral hemodynamic parameters were calculated. With respect to SR, AF triggered a higher variability of the cerebral hemodynamic variables which increases proceeding towards the distal circulation, reaching the maximum extent at the arteriolar and capillary levels. This variability led to critical cerebral hemodynamic events of excessive pressure or reduced blood flow: 303 hypoperfusions occurred at the arteriolar level, while 387 hypertensive events occurred at the capillary level during AF. By contrast, neither hypoperfusions nor hypertensive events occurred during SR. Thus, the impact of AF per se on cerebral hemodynamics candidates as a relevant mechanism into the genesis of AF-related cognitive impairment/dementia.

Driver fatigue and highway driving: a simulator study.

PubMed

Ting, Ping-Huang; Hwang, Jiun-Ren; Doong, Ji-Liang; Jeng, Ming-Chang

2008-06-09

Long duration of driving is a significant cause of fatigue-related accidents on motorways or major roadways. The fatigue caused by driving for extended periods acutely impairs driver alertness and performance and can compromise transportation safety. This study quantitatively measured the progression of driver fatigue and identified the conservative safe duration of continuous highway driving. Thirty young male subjects were analyzed during 90 min of laboratory-simulated highway driving. Sleepiness ratings (SSS) and reaction time (RT) tests were used to assess impairment of driver alertness and vigilance. Additionally, various measures of driving performance recorded throughout the experiment were used to measure temporal deterioration of driver performance from alert to fatigued using principal component analysis (PCA). The analytical results revealed that SSS scores, reaction times (RTs) and unstable driving performance significantly increased over time, indicating that excessive driving time is a significant fatigue factor and potential cause of fatigue-related accidents. Moreover, the analytical results indicated that 80 min was the safe limit for monotonous highway driving. Based on the experimental findings of this study, public awareness of the adverse affects of driver fatigue during long-distance driving should be enhanced. This study provides explicit information of fatigue development that can be used to prevent fatigue-related accidents.

Ecosystem Modeling Applied to Nutrient Criteria Development in Rivers

NASA Astrophysics Data System (ADS)

Carleton, James N.; Park, Richard A.; Clough, Jonathan S.

2009-09-01

Threshold concentrations for biological impairment by nutrients are difficult to quantify in lotic systems, yet States and Tribes in the United States are charged with developing water quality criteria to protect these ecosystems from excessive enrichment. The analysis described in this article explores the use of the ecosystem model AQUATOX to investigate impairment thresholds keyed to biological indexes that can be simulated. The indexes selected for this exercise include percentage cyanobacterial biomass of sestonic algae, and benthic chlorophyll a. The calibrated model was used to analyze responses of these indexes to concurrent reductions in phosphorus, nitrogen, and suspended sediment in an enriched upper Midwestern river. Results suggest that the indexes would respond strongly to changes in phosphorus and suspended sediment, and less strongly to changes in nitrogen concentration. Using simulated concurrent reductions in all three water quality constituents, a total phosphorus concentration of 0.1 mg/l was identified as a threshold concentration, and therefore a hypothetical water quality criterion, for prevention of both excessive periphyton growth and sestonic cyanobacterial blooms. This kind of analysis is suggested as a way to evaluate multiple contrasting impacts of hypothetical nutrient and sediment reductions and to define nutrient criteria or target concentrations that balance multiple management objectives concurrently.

Use of Simulation Learning Experiences in Physical Therapy Entry-to-Practice Curricula: A Systematic Review

PubMed Central

Carnahan, Heather; Herold, Jodi

2015-01-01

ABSTRACT Purpose: To review the literature on simulation-based learning experiences and to examine their potential to have a positive impact on physiotherapy (PT) learners' knowledge, skills, and attitudes in entry-to-practice curricula. Method: A systematic literature search was conducted in the MEDLINE, CINAHL, Embase Classic+Embase, Scopus, and Web of Science databases, using keywords such as physical therapy, simulation, education, and students. Results: A total of 820 abstracts were screened, and 23 articles were included in the systematic review. While there were few randomized controlled trials with validated outcome measures, some discoveries about simulation can positively affect the design of the PT entry-to-practice curricula. Using simulators to provide specific output feedback can help students learn specific skills. Computer simulations can also augment students' learning experience. Human simulation experiences in managing the acute patient in the ICU are well received by students, positively influence their confidence, and decrease their anxiety. There is evidence that simulated learning environments can replace a portion of a full-time 4-week clinical rotation without impairing learning. Conclusions: Simulation-based learning activities are being effectively incorporated into PT curricula. More rigorously designed experimental studies that include a cost–benefit analysis are necessary to help curriculum developers make informed choices in curriculum design. PMID:25931672

Sustaining prospective memory functioning in amnestic mild cognitive impairment: A lifespan approach to the critical role of encoding.

PubMed

Pereira, Antonina; Altgassen, Mareike; Atchison, Lesley; de Mendonça, Alexandre; Ellis, Judi

2018-04-16

Prospective memory (PM), the ability to remember to perform future activities, is a fundamental requirement for independent living. PM tasks pervade our daily lives, and PM failures represent one of the most prominent memory concerns across the entire life span. This study aimed to address this issue by exploring the potential benefits of specific encoding strategies on memory for intentions across healthy adulthood and in the early stages of cognitive impairment. PM performance was explored through an experimental paradigm in 96 participants: 32 amnestic mild cognitively impaired patients aged 64-87 years (M = 6.75, SD = 5.88), 32 healthy older adults aged 62-84 years (M = 76.06, SD = 6.03), and 32 younger adults 18-22 years (M = 19.75, SD = 1.16). The potential benefit of the use of enactment (i.e., physically simulating the intended action) at encoding to support an autonomous performance despite neuronal degeneration was assessed. PM was consistently identified as a sensitive and specific indicator of cognitive impairment. Importantly, enacted encoding was consistently beneficial for PM performance of all the participants, but especially so in the case of healthy and cognitively impaired older adults. These positive results have unveiled the potential of this encoding technique to optimize attentional demands through an adaptive allocation of strategic resources across both healthy and cognitively impaired samples. Theoretical implications of this work are discussed as well as the considerable translational potential to improve social well-being. A better understanding of the strategies that can enhance PM offers the potential for cost-effective and widely applicable tools which may support independent living across the adult life span. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Older Adults with Mild Cognitive Impairments Show Less Driving Errors after a Multiple Sessions Simulator Training Program but Do Not Exhibit Long Term Retention.

PubMed

Teasdale, Normand; Simoneau, Martin; Hudon, Lisa; Germain Robitaille, Mathieu; Moszkowicz, Thierry; Laurendeau, Denis; Bherer, Louis; Duchesne, Simon; Hudon, Carol

2016-01-01

The driving performance of individuals with mild cognitive impairment (MCI) is suboptimal when compared to healthy older adults. It is expected that the driving will worsen with the progression of the cognitive decline and thus, whether or not these individuals should continue to drive is a matter of debate. The aim of the study was to provide support to the claim that individuals with MCI can benefit from a training program and improve their overall driving performance in a driving simulator. Fifteen older drivers with MCI participated in five training sessions in a simulator (over a 21-day period) and in a 6-month recall session. During training, they received automated auditory feedback on their performance when an error was noted about various maneuvers known to be suboptimal in MCI individuals (for instance, weaving, omitting to indicate a lane change, to verify a blind spot, or to engage in a visual search before crossing an intersection). The number of errors was compiled for eight different maneuvers for all sessions. For the initial five sessions, a gradual and significant decrease in the number of errors was observed, indicating learning and safer driving. The level of performance, however, was not maintained at the 6-month recall session. Nevertheless, the initial learning observed opens up possibilities to undertake more regular interventions to maintain driving skills and safe driving in MCI individuals.

A domain-specific system for representing knowledge of both man-made objects and human actions. Evidence from a case with an association of deficits.

PubMed

Vannuscorps, Gilles; Pillon, Agnesa

2011-07-01

We report the single-case study of a brain-damaged individual, JJG, presenting with a conceptual deficit and whose knowledge of living things, man-made objects, and actions was assessed. The aim was to seek for empirical evidence pertaining to the issue of how conceptual knowledge of objects, both living things and man-made objects, is related to conceptual knowledge of actions at the functional level. We first found that JJG's conceptual knowledge of both man-made objects and actions was similarly impaired while his conceptual knowledge of living things was spared as well as his knowledge of unique entities. We then examined whether this pattern of association of a conceptual deficit for both man-made objects and actions could be accounted for, first, by the "sensory/functional" and, second, the "manipulability" account for category-specific conceptual impairments advocated within the Feature-Based-Organization theory of conceptual knowledge organization, by assessing, first, patient's knowledge of sensory compared to functional features, second, his knowledge of manipulation compared to functional features and, third, his knowledge of manipulable compared to non-manipulable objects and actions. The later assessment also allowed us to evaluate an account for the deficits in terms of failures of simulating the hand movements implied by manipulable objects and manual actions. The findings showed that, contrary to the predictions made by the "sensory/functional", the "manipulability", and the "failure-of-simulating" accounts for category-specific conceptual impairments, the patient's association of deficits for both man-made objects and actions was not associated with a disproportionate impairment of functional compared to sensory knowledge or of manipulation compared to functional knowledge; manipulable items were not more impaired than non-manipulable items either. In the general discussion, we propose to account for the patient's association of deficits by the hypothesis that concepts whose core property is that of being a mean of achieving a goal - like the concepts of man-made objects and of actions - are learned, represented and processed by a common domain-specific conceptual system, which would have evolved to allow human beings to quickly and efficiently design and understand means to achieve goals and purposes. Copyright © 2011 Elsevier Ltd. All rights reserved.

Effects of insulin and exercise on rat hindlimb muscles after simulated microgravity

NASA Technical Reports Server (NTRS)

Stump, Craig S.; Balon, Thomas W.; Tipton, Charles M.

1992-01-01

The effect of simulated microgravity on the insulin- and exercise-stimulated glucose uptake and metabolism in the hindlimb muscles of rats was investigated using three groups of rats suspended at 45 head-down tilt (SUS) for 14 days: (1) cage control, (2) exercising (treadmill running) control, and (3) rats subjected to suspension followed by exercise (SUS-E). It was found that the suspension of rats with hindlimbs non-weight bearing led to enhanced muscle responses to insulin and exercise, when these stimuli were applied separately. However, the insulin affect appeared to be impaired after exercise for the SUS-E rats, especially for the soleus muscle.

Fuzzy-based simulation of real color blindness.

PubMed

Lee, Jinmi; dos Santos, Wellington P

2010-01-01

About 8% of men are affected by color blindness. That population is at a disadvantage since they cannot perceive a substantial amount of the visual information. This work presents two computational tools developed to assist color blind people. The first one tests color blindness and assess its severity. The second tool is based on Fuzzy Logic, and implements a method proposed to simulate real red and green color blindness in order to generate synthetic cases of color vision disturbance in a statistically significant amount. Our purpose is to develop correction tools and obtain a deeper understanding of the accessibility problems faced by people with chromatic visual impairment.

Constant envelope OFDM scheme for 6PolSK-QPSK

NASA Astrophysics Data System (ADS)

Li, Yupeng; Ding, Ding

2018-03-01

A constant envelope OFDM scheme with phase modulator (PM-CE-OFDM) for 6PolSK-QPSK modulation was demonstrated. Performance under large fiber launch power is measured to check its advantages in counteracting fiber nonlinear impairments. In our simulation, PM-CE-OFDM, RF-assisted constant envelope OFDM (RF-CE-OFDM) and conventional OFDM (Con-OFDM) are transmitted through 80 km standard single mode fiber (SSMF) single channel and WDM system. Simulation results confirm that PM-CE-OFDM has best performance in resisting fiber nonlinearity. In addition, benefiting from the simple system structure, the complexity and cost of PM-CE-OFDM system could be reduced effectively.

Cognitive performance deficits in a simulated climb of Mount Everest - Operation Everest II

NASA Technical Reports Server (NTRS)

Kennedy, R. S.; Dunlap, W. P.; Banderet, L. E.; Smith, M. G.; Houston, C. S.

1989-01-01

Cognitive function at simulated altitude was investigated in a repeated-measures within-subject study of performance by seven volunteers in a hypobaric chamber, in which atmospheric pressure was systematically lowered over a period of 40 d to finally reach a pressure equivalent to 8845 m, the approximate height of Mount Everest. The automated performance test system employed compact computer design; automated test administrations, data storage, and retrieval; psychometric properties of stability and reliability; and factorial richness. Significant impairments of cognitive function were seen for three of the five tests in the battery; on two tests, grammatical reasoning and pattern comparison, every subject showed a substantial decrement.

Numerical Simulation of cardiovascular deconditioning in different reduced gravity exposure scenarios. Parabolic flight validation.

NASA Astrophysics Data System (ADS)

Perez-Poch, Antoni; Gonzalez, Daniel

Numerical models and simulations are an emerging area of research in human physiology. As complex numerical models are available, along with high-speed computing technologies, it is possible to produce more accurate predictions of the long-term effects of reduced gravity on the human body. NELME (Numerical Emulation of Long-Term Microgravity Effects) has been developed as an electrical-like control system model of the pysiological changes that may arise when gravity changes are applied to the cardiovascular system. Validation of the model has been carried out in parabolic flights at UPC BarcelonaTech Platform. A number of parabolas of up to 8 seconds were performed at Sabadell Airport with an aerobatic single-engine CAP10B plane capable of performing such maneuvres. Heart rate, arterial pressure, and gravity data was collected and compared to the output obtained from the model in order to optimize its parameters. The model is then able to perform simulations for long-term periods of exposure to microgravity, and then the risk for a major malfunction is evaluated. Vascular resistance is known to be impaired during a long-term mission. This effects are not fully understood, and the model is capable of providing a continuous thread of simulated scenarios, while varying gravity in a nearly-continuous way. Aerobic exercise as countermeasure has been simulated as a periodic perturbation into the simulated physiological system. Results are discussed in terms of the validaty and reliability of the outcomes from the model, that have been found compatible with the available data in the literature. Different gender sensitivities to microgravity exposure are discussed. Also thermal stress along with exercise, as it happens in the case of Extravehicular activity is smulated. Results show that vascular resistance is significantly impared (p<0,05) at gravity levels less than 0,4g, when exposed for a period of time longer than 16 days. This degree of impairement is comparable with that resulting from a microgravity exposure. These results suggest that long-term activities on the surface of Mars may have a greater impact on the cardiovascular health than previously thought.

Contributions of Altered Stretch Reflex Coordination to Arm Impairments Following Stroke

PubMed Central

Ravichandran, Vengateswaran J.; Krutky, Matthew A.; Perreault, Eric J.

2010-01-01

Patterns of stereotyped muscle coactivation, clinically referred to as synergies, emerge following stroke and impair arm function. Although researchers have focused on cortical contributions, there is growing evidence that altered stretch reflex pathways may also contribute to impairment. However, most previous reflex studies have focused on passive, single-joint movements without regard to their coordination during volitional actions. The purpose of this study was to examine the effects of stroke on coordinated activity of stretch reflexes elicited in multiple arm muscles following multijoint perturbations. We hypothesized that cortical injury results in increased stretch reflexes of muscles characteristic of the abnormal flexor synergy during active arm conditions. To test this hypothesis, we used a robot to apply position perturbations to impaired arms of 10 stroke survivors and dominant arms of 8 healthy age-matched controls. Corresponding reflexes were assessed during volitional contractions simulating different levels of gravitational support, as well as during voluntary flexion and extension of the elbow and shoulder. Reflexes were quantified by average rectified surface electromyogram, recorded from eight muscles spanning the elbow and shoulder. Reflex coordination was quantified using an independent components analysis. We found stretch reflexes elicited in the stroke group were significantly less sensitive to changes in background muscle activation compared with those in the control group (P < 0.05). We also observed significantly increased reflex coupling between elbow flexor and shoulder abductor–extensor muscles in stroke subjects relative to that in control subjects. This increased coupling was present only during volitional tasks that required elbow flexion (P < 0.001), shoulder extension (P < 0.01), and gravity opposition (P < 0.01), but not during the “no load” condition. During volitional contractions, reflex amplitudes scaled with the level of impairment, as assessed by Fugl-Meyer scores (r2 = 0.63; P < 0.05). We conclude that altered reflex coordination is indicative of motor impairment level and may contribute to impaired arm function following stroke. PMID:20962072

Nutrient and sediment concentrations, yields, and loads in impaired streams and rivers in the Taunton River Basin, Massachusetts, 1997-2008

USGS Publications Warehouse

Barbaro, Jeffrey R.; Sorenson, Jason R.

2013-01-01

Rapid development, population growth, and the changes in land and water use accompanying development are placing increasing stress on water resources in the Taunton River Basin. An assessment by the Massachusetts Department of Environmental Protection determined that a number of tributary streams to the Taunton River are impaired for a variety of beneficial uses because of nutrient enrichment. Most of the impaired reaches are in the Matfield River drainage area in the vicinity of the City of Brockton. In addition to impairments of stream reaches in the basin, discharge of nutrient-rich water from the Taunton River contributes to eutrophication of Mount Hope and Narragansett Bays. To assess water quality and loading in the impaired tributary stream reaches in the basin, the U.S. Geological Survey, in cooperation with the Massachusetts Department of Environmental Protection compiled existing water-quality data from previous studies for the period 1997-2006, developed and calibrated a Hydrological Simulation Program-FORTRAN (HSPF) precipitation-runoff model to simulate streamflow in areas of the basin that contain the impaired reaches for the same time period, and collected additional streamflow and water-quality data from sites on the Matfield and Taunton Rivers in 2008. A majority of the waterquality samples used in the study were collected between 1999 and 2006. Overall, the concentration, yield, and load data presented in this report represent water-quality conditions in the basin for the period 1997-2008. Water-quality data from 52 unique sites were used in the study. Most of the samples from previous studies were collected between June and September under dry weather conditions. Simulated or measured daily mean streamflow and water-quality data were used to estimate constituent yields and loads in the impaired tributary stream reaches and the main stem of the Taunton River and to develop yield-duration plots for reaches with sufficient water-quality data. Total phosphorus concentrations in the impaired-reach areas ranged from 0.0046 to 0.91 milligrams per liter (mg/L) in individual samples (number of samples (n)=331), with a median of 0.090 mg/L; total nitrogen concentrations ranged from 0.34 to 14 mg/L in individual samples (n=139), with a median of 1.35 mg/L; and total suspended solids concentrations ranged from 2/d) for total phosphorus and 100 lb/mi2/d for total nitrogen in these reaches. In most of the impaired reaches not affected by the Brockton Advanced Water Reclamation Facility outfall, yields were lower than in reaches downstream from the outfall, and the difference between measured and threshold yields was fairly uniform over a wide range of flows, suggesting that multiple processes contribute to nonpoint loading in these reaches. The Northeast and Mid-Atlantic SPAtially-Referenced Regression On Watershed (SPARROW) models for total phosphorus and total nitrogen also were used to estimate annual nutrient loads in the impaired tributary stream reaches and main stem of the Taunton River and predict the distribution of these loads among point and diffuse sources in reach drainage areas. SPARROW is a regional, statistical model that relates nutrient loads in streams to upstream sources and land-use characteristics and can be used to make predictions for streams that do not have nutrient-load data. The model predicts mean annual loads based on longterm streamflow and water-quality data and nutrient source conditions for the year 2002. Predicted mean annual nutrient loads from the SPARROW models were consistent with the measured yield and load data from sampling sites in the basin. For conditions in 2002, the Brockton Advanced Water Reclamation Facility outfall accounted for over 75 percent of the total nitrogen load and over 93 percent of the total phosphorus load in the Salisbury Plain and Matfield Rivers downstream from the outfall. Municipal point sources also accounted for most of the load in the main stem of the Taunton River. Multiple municipal wastewater discharges in the basin accounted for about 76 and 46 percent of the delivered loads of total phosphorus and total nitrogen, respectively, to Mount Hope Bay. For similarly sized watersheds, total delivered loads were lower in watersheds without point sources compared to those with point sources, and sources associated with developed land accounted for most of the delivered phosphorus and nitrogen loads to the impaired reaches. The concentration, yield, and load data evaluated in this study may not be representative of current (2012) point-source loading in the basin; in particular, most of the water-quality data used in the study (1999-2006) were collected prior to completion of upgrades to the Brockton Advanced Water Reclamation Facility that reduced total phosphorus and nitrogen concentrations in treated effluent. Effluent concentration data indicate that, for a given flow rate, effluent loads of total phosphorus and total nitrogen declined by about 80 and 30 percent, respectively, between the late 1990s and 2008 in response to plant upgrades. Consequently, current (2012) water-quality conditions in the impaired reaches downstream from the facility likely have improved compared to conditions described in the report.

INTEGRITY -- Integrated Human Exploration Mission Simulation Facility

NASA Astrophysics Data System (ADS)

Henninger, D.; Tri, T.; Daues, K.

It is proposed to develop a high -fidelity ground facil ity to carry out long-duration human exploration mission simulations. These would not be merely computer simulations - they would in fact comprise a series of actual missions that just happen to stay on earth. These missions would include all elements of an actual mission, using actual technologies that would be used for the real mission. These missions would also include such elements as extravehicular activities, robotic systems, telepresence and teleoperation, surface drilling technology--all using a simulated planetary landscape. A sequence of missions would be defined that get progressively longer and more robust, perhaps a series of five or six missions over a span of 10 to 15 years ranging in durat ion from 180 days up to 1000 days. This high-fidelity ground facility would operate hand-in-hand with a host of other terrestrial analog sites such as the Antarctic, Haughton Crater, and the Arizona desert. Of course, all of these analog mission simulations will be conducted here on earth in 1-g, and NASA will still need the Shuttle and ISS to carry out all the microgravity and hypogravity science experiments and technology validations. The proposed missions would have sufficient definition such that definitive requirements could be derived from them to serve as direction for all the program elements of the mission. Additionally, specific milestones would be established for the "launch" date of each mission so that R&D programs would have both good requirements and solid milestones from which to build their implementation plans. Mission aspects that could not be directly incorporated into the ground facility would be simulated via software. New management techniques would be developed for evaluation in this ground test facility program. These new techniques would have embedded metrics which would allow them to be continuously evaluated and adjusted so that by the time the sequence of missions is completed, the best management techniques will have been developed, implemented, and validated. A trained cadre of managers experienced with a large, complex program would then be available. Three other critical items of this approach are as follows: 1) International Cooperation/Collaboration. New paradigms and new techniques for international collaboration would be developed. These paradigms can be developed to include built-in metrics to allow for improvements ultimately to yield proven paradigms for application in the real mission. Note that since this approach is much lower cost than an actual flight mission, smaller countries that could not afford to participate in a program as large as the ISS can become partners. As a result, these nations--along with their citizens--become advocates for human space exploration as well. Since eventual human planetary exploration missions are likely to be truly international, the means for building the requisite working relationships are through cooperative research and technology development activities. 2) Commercial Partnering. Improved paradigms for commercial partnering would be developed - both U.S. and international commercial entities. An examination of what commercial entities would like to gain, what they would expect to contribute, and what NASA wants out of such a relationship would be determined to develop appropriate paradigms. Again, metrics would be included such that continual evaluations can be conducted and adjustments can be made to the working paradigms. Then, after these ground missions are completed, a proven set of paradigms (and a cadre of people trained and comfortable with their use) would be available for the actual mission. Again, since this is a much lower cost program (lower than an actual flight mission), smaller domestic and international commercial entities can participate. 3) Academic Partnering. Improved paradigms for academic partnering can be developed -- both U.S. and international academic institutions. Academic institutions represent a tremendous pool of expertise and creative talent - just what is need for a human planetary exp loration mission. Academia would likely view this ground test facility as a tremendous teaching tool for a variety of disciplines, including science, engineering, medicine, and management.

Driving while drinking: performance impairments resulting from social drinking.

PubMed

Charlton, Samuel G; Starkey, Nicola J

2015-01-01

Previous research has shown that the effects of alcohol on drivers' performance can differ depending on whether blood alcohol concentrations are increasing or decreasing. The present research used a more ecologically representative alcohol consumption protocol in order to determine whether the same pattern of driver impairment would occur when drinking occurred in social groups over a longer period of time. Forty-four participants were assigned to one of two alcohol dose conditions or a placebo control group and consumed alcohol in groups of three (typically one participant from each condition) such that they gradually reached their target BAC (.05 or .08) and maintained it for 1 h. The participants completed a series of cognitive tests (Cogstate test battery) and a simulated driving task (driver attention inhibition and reaction test) over the course of their intoxication curve (approximately 4 h). The results showed strong placebo effects on ratings of subjective intoxication. Driving and cognitive performance both showed dose-dependent alcohol impairment, and some measures displayed acute protracted error. The findings provide strong evidence of expectancy effects in contributing to self-perceptions of intoxication. Copyright © 2014 Elsevier Ltd. All rights reserved.

Finite Element Modeling of the Posterior Eye in Microgravity

NASA Technical Reports Server (NTRS)

Feola, Andrew; Raykin, Julia; Mulugeta, Lealem; Gleason, Rudolph; Myers, Jerry G.; Nelson, Emily S.; Samuels, Brian; Ethier, C. Ross

2015-01-01

Microgravity experienced during spaceflight affects astronauts in various ways, including weakened muscles and loss of bone density. Recently, visual impairment and intracranial pressure (VIIP) syndrome has become a major concern for space missions lasting longer than 30 days. Astronauts suffering from VIIP syndrome have changes in ocular anatomical and visual impairment that persist after returning to earth. It is hypothesized that a cephalad fluid shift in microgravity may increase the intracranial pressure (ICP), which leads to an altered biomechanical environment of the posterior globe and optic nerve sheath (ONS).Currently, there is a lack of knowledge of how elevated ICP may lead to vision impairment and connective tissue changes in VIIP. Our goal was to develop a finite element model to simulate the acute effects of elevated ICP on the posterior eye and optic nerve sheath. We used a finite element (FE) analysis approach to understand the response of the lamina cribrosa and optic nerve to the elevations in ICP thought to occur in microgravity and to identify which tissue components have the greatest impact on strain experienced by optic nerve head tissues.

Development of a Virtual Reality Assessment of Everyday Living Skills

PubMed Central

Ruse, Stacy A.; Davis, Vicki G.; Atkins, Alexandra S.; Krishnan, K. Ranga R.; Fox, Kolleen H.; Harvey, Philip D.; Keefe, Richard S.E.

2014-01-01

Cognitive impairments affect the majority of patients with schizophrenia and these impairments predict poor long term psychosocial outcomes.  Treatment studies aimed at cognitive impairment in patients with schizophrenia not only require demonstration of improvements on cognitive tests, but also evidence that any cognitive changes lead to clinically meaningful improvements.  Measures of “functional capacity” index the extent to which individuals have the potential to perform skills required for real world functioning.  Current data do not support the recommendation of any single instrument for measurement of functional capacity.  The Virtual Reality Functional Capacity Assessment Tool (VRFCAT) is a novel, interactive gaming based measure of functional capacity that uses a realistic simulated environment to recreate routine activities of daily living. Studies are currently underway to evaluate and establish the VRFCAT’s sensitivity, reliability, validity, and practicality. This new measure of functional capacity is practical, relevant, easy to use, and has several features that improve validity and sensitivity of measurement of function in clinical trials of patients with CNS disorders. PMID:24798174

Contribution of finger tracing to the recognition of Chinese characters.

PubMed

Yim-Ng, Y Y; Varley, R; Andrade, J

2000-01-01

Finger tracing is a simulation of the act of writing without the use of pen and paper. It is claimed to help in the processing of Chinese characters, possibly by providing additional motor coding. In this study, blindfolded subjects were equally good at identifying Chinese characters and novel visual stimuli through passive movements made with the index finger of the preferred hand and those made with the last finger of that hand. This suggests that finger tracing provides a relatively high level of coding specific to individual characters, but non-specific to motor effectors. Beginning each stroke from the same location, i.e. removing spatial information, impaired recognition of the familiar characters and the novel nonsense figures. Passively tracing the strokes in a random sequence also impaired recognition of the characters. These results therefore suggest that the beneficial effect of finger tracing on writing or recall of Chinese characters is mediated by sequence and spatial information embedded in the motor movements, and that proprioceptive channel may play a part in mediating visuo-spatial information. Finger tracing may be a useful strategy for remediation of Chinese language impairments.

Effects of aging on perception of motion

NASA Astrophysics Data System (ADS)

Kaur, Manpreet; Wilder, Joseph; Hung, George; Julesz, Bela

1997-09-01

Driving requires two basic visual components: 'visual sensory function' and 'higher order skills.' Among the elderly, it has been observed that when attention must be divided in the presence of multiple objects, their attentional skills and relational processes, along with impairment of basic visual sensory function, are markedly impaired. A high frame rate imaging system was developed to assess the elderly driver's ability to locate and distinguish computer generated images of vehicles and to determine their direction of motion in a simulated intersection. Preliminary experiments were performed at varying target speeds and angular displacements to study the effect of these parameters on motion perception. Results for subjects in four different age groups, ranging from mid- twenties to mid-sixties, show significantly better performance for the younger subjects as compared to the older ones.

Effects of Thermal Status on Markers of Blood Coagulation During Simulated Hemorrhage

DTIC Science & Technology

2016-04-01

consumption would further reduce LBNP tolerance in the presence of moderate skin temperatures (35°C). Against our expectations, LBNP tolerance was not...exerted an effect sufficient in magnitude to mask any further impairments induced by additional dehydration and increases in body temperature ...Ventilatory parameters ( ventilation , tidal volume and breathing rate) were measured (body temperature and pressure saturated) using an automated gas

Heart Rate Response During Mission-Critical Tasks After Space Flight

NASA Technical Reports Server (NTRS)

Arzeno, Natalia M.; Lee, S. M. C.; Stenger, M. B.; Lawrence, E. L.; Platts, S. H.; Bloomberg, J. J.

2010-01-01

Adaptation to microgravity could impair crewmembers? ability to perform required tasks upon entry into a gravity environment, such as return to Earth, or during extraterrestrial exploration. Historically, data have been collected in a controlled testing environment, but it is unclear whether these physiologic measures result in changes in functional performance. NASA?s Functional Task Test (FTT) aims to investigate whether adaptation to microgravity increases physiologic stress and impairs performance during mission-critical tasks. PURPOSE: To determine whether the well-accepted postflight tachycardia observed during standard laboratory tests also would be observed during simulations of mission-critical tasks during and after recovery from short-duration spaceflight. METHODS: Five astronauts participated in the FTT 30 days before launch, on landing day, and 1, 6, and 30 days after landing. Mean heart rate (HR) was measured during 5 simulations of mission-critical tasks: rising from (1) a chair or (2) recumbent seated position followed by walking through an obstacle course (egress from a space vehicle), (3) translating graduated masses from one location to another (geological sample collection), (4) walking on a treadmill at 6.4 km/h (ambulation on planetary surface), and (5) climbing 40 steps on a passive treadmill ladder (ingress to lander). For tasks 1, 2, 3, and 5, astronauts were encouraged to complete the task as quickly as possible. Time to complete tasks and mean HR during each task were analyzed using repeated measures ANOVA and ANCOVA respectively, in which task duration was a covariate. RESULTS: Landing day HR was higher (P < 0.05) than preflight during the upright seat egress (7%+/-3), treadmill walk (13%+/-3) and ladder climb (10%+/-4), and HR remained elevated during the treadmill walk 1 day after landing. During tasks in which HR was not elevated on landing day, task duration was significantly greater on landing day (recumbent seat egress: 25%+/-14 and mass translation: 26%+/-12; P < 0.05). CONCLUSION: Elevated HR and increased task duration during postflight simulations of mission-critical tasks is suggestive of spaceflight-induced deconditioning. Following short-duration microgravity missions (< 16 d), work performance may be transiently impaired, but recovery is rapid.

Objective Prediction of Hearing Aid Benefit Across Listener Groups Using Machine Learning: Speech Recognition Performance With Binaural Noise-Reduction Algorithms.

PubMed

Schädler, Marc R; Warzybok, Anna; Kollmeier, Birger

2018-01-01

The simulation framework for auditory discrimination experiments (FADE) was adopted and validated to predict the individual speech-in-noise recognition performance of listeners with normal and impaired hearing with and without a given hearing-aid algorithm. FADE uses a simple automatic speech recognizer (ASR) to estimate the lowest achievable speech reception thresholds (SRTs) from simulated speech recognition experiments in an objective way, independent from any empirical reference data. Empirical data from the literature were used to evaluate the model in terms of predicted SRTs and benefits in SRT with the German matrix sentence recognition test when using eight single- and multichannel binaural noise-reduction algorithms. To allow individual predictions of SRTs in binaural conditions, the model was extended with a simple better ear approach and individualized by taking audiograms into account. In a realistic binaural cafeteria condition, FADE explained about 90% of the variance of the empirical SRTs for a group of normal-hearing listeners and predicted the corresponding benefits with a root-mean-square prediction error of 0.6 dB. This highlights the potential of the approach for the objective assessment of benefits in SRT without prior knowledge about the empirical data. The predictions for the group of listeners with impaired hearing explained 75% of the empirical variance, while the individual predictions explained less than 25%. Possibly, additional individual factors should be considered for more accurate predictions with impaired hearing. A competing talker condition clearly showed one limitation of current ASR technology, as the empirical performance with SRTs lower than -20 dB could not be predicted.

Objective Prediction of Hearing Aid Benefit Across Listener Groups Using Machine Learning: Speech Recognition Performance With Binaural Noise-Reduction Algorithms

PubMed Central

Schädler, Marc R.; Warzybok, Anna; Kollmeier, Birger

2018-01-01

The simulation framework for auditory discrimination experiments (FADE) was adopted and validated to predict the individual speech-in-noise recognition performance of listeners with normal and impaired hearing with and without a given hearing-aid algorithm. FADE uses a simple automatic speech recognizer (ASR) to estimate the lowest achievable speech reception thresholds (SRTs) from simulated speech recognition experiments in an objective way, independent from any empirical reference data. Empirical data from the literature were used to evaluate the model in terms of predicted SRTs and benefits in SRT with the German matrix sentence recognition test when using eight single- and multichannel binaural noise-reduction algorithms. To allow individual predictions of SRTs in binaural conditions, the model was extended with a simple better ear approach and individualized by taking audiograms into account. In a realistic binaural cafeteria condition, FADE explained about 90% of the variance of the empirical SRTs for a group of normal-hearing listeners and predicted the corresponding benefits with a root-mean-square prediction error of 0.6 dB. This highlights the potential of the approach for the objective assessment of benefits in SRT without prior knowledge about the empirical data. The predictions for the group of listeners with impaired hearing explained 75% of the empirical variance, while the individual predictions explained less than 25%. Possibly, additional individual factors should be considered for more accurate predictions with impaired hearing. A competing talker condition clearly showed one limitation of current ASR technology, as the empirical performance with SRTs lower than −20 dB could not be predicted. PMID:29692200

A multilingual audiometer simulator software for training purposes.

PubMed

Kompis, Martin; Steffen, Pascal; Caversaccio, Marco; Brugger, Urs; Oesch, Ivo

2012-04-01

A set of algorithms, which allows a computer to determine the answers of simulated patients during pure tone and speech audiometry, is presented. Based on these algorithms, a computer program for training in audiometry was written and found to be useful for teaching purposes. To develop a flexible audiometer simulator software as a teaching and training tool for pure tone and speech audiometry, both with and without masking. First a set of algorithms, which allows a computer to determine the answers of a simulated, hearing-impaired patient, was developed. Then, the software was implemented. Extensive use was made of simple, editable text files to define all texts in the user interface and all patient definitions. The software 'audiometer simulator' is available for free download. It can be used to train pure tone audiometry (both with and without masking), speech audiometry, measurement of the uncomfortable level, and simple simulation tests. Due to the use of text files, the user can alter or add patient definitions and all texts and labels shown on the screen. So far, English, French, German, and Portuguese user interfaces are available and the user can choose between German or French speech audiometry.

Fetal Alcohol Syndrome, Chemo-Biology and OMICS: Ethanol Effects on Vitamin Metabolism During Neurodevelopment as Measured by Systems Biology Analysis

PubMed Central

Feltes, Bruno César; de Faria Poloni, Joice; Nunes, Itamar José Guimarães

2014-01-01

Abstract Fetal alcohol syndrome (FAS) is a prenatal disease characterized by fetal morphological and neurological abnormalities originating from exposure to alcohol. Although FAS is a well-described pathology, the molecular mechanisms underlying its progression are virtually unknown. Moreover, alcohol abuse can affect vitamin metabolism and absorption, although how alcohol impairs such biochemical pathways remains to be elucidated. We employed a variety of systems chemo-biology tools to understand the interplay between ethanol metabolism and vitamins during mouse neurodevelopment. For this purpose, we designed interactomes and employed transcriptomic data analysis approaches to study the neural tissue of Mus musculus exposed to ethanol prenatally and postnatally, simulating conditions that could lead to FAS development at different life stages. Our results showed that FAS can promote early changes in neurotransmitter release and glutamate equilibrium, as well as an abnormal calcium influx that can lead to neuroinflammation and impaired neurodifferentiation, both extensively connected with vitamin action and metabolism. Genes related to retinoic acid, niacin, vitamin D, and folate metabolism were underexpressed during neurodevelopment and appear to contribute to neuroinflammation progression and impaired synapsis. Our results also indicate that genes coding for tubulin, tubulin-associated proteins, synapse plasticity proteins, and proteins related to neurodifferentiation are extensively affected by ethanol exposure. Finally, we developed a molecular model of how ethanol can affect vitamin metabolism and impair neurodevelopment. PMID:24816220

Mechanisms underlying selecting objects for action

PubMed Central

Wulff, Melanie; Laverick, Rosanna; Humphreys, Glyn W.; Wing, Alan M.; Rotshtein, Pia

2015-01-01

We assessed the factors which affect the selection of objects for action, focusing on the role of action knowledge and its modulation by distracters. Fourteen neuropsychological patients and 10 healthy aged-matched controls selected pairs of objects commonly used together among distracters in two contexts: with real objects and with pictures of the same objects presented sequentially on a computer screen. Across both tasks, semantically related distracters led to slower responses and more errors than unrelated distracters and the object actively used for action was selected prior to the object that would be passively held during the action. We identified a sub-group of patients (N = 6) whose accuracy was 2SDs below the controls performances in the real object task. Interestingly, these impaired patients were more affected by the presence of unrelated distracters during both tasks than intact patients and healthy controls. Note that the impaired patients had lesions to left parietal, right anterior temporal and bilateral pre-motor regions. We conclude that: (1) motor procedures guide object selection for action, (2) semantic knowledge affects action-based selection, (3) impaired action decision making is associated with the inability to ignore distracting information and (4) lesions to either the dorsal or ventral visual stream can lead to deficits in making action decisions. Overall, the data indicate that impairments in everyday tasks can be evaluated using a simulated computer task. The implications for rehabilitation are discussed. PMID:25954177

A Biomarker Combining Imaging and Neuropsychological Assessment for Tracking Early Alzheimer's Disease in Clinical Trials.

PubMed

Verma, Nishant; Beretvas, S Natasha; Pascual, Belen; Masdeu, Joseph C; Markey, Mia K

2018-03-14

Combining optimized cognitive (Alzheimer's Disease Assessment Scale- Cognitive subscale, ADAS-Cog) and atrophy markers of Alzheimer's disease for tracking progression in clinical trials may provide greater sensitivity than currently used methods, which have yielded negative results in multiple recent trials. Furthermore, it is critical to clarify the relationship among the subcomponents yielded by cognitive and imaging testing, to address the symptomatic and anatomical variability of Alzheimer's disease. Using latent variable analysis, we thoroughly investigated the relationship between cognitive impairment, as assessed on the ADAS-Cog, and cerebral atrophy. A biomarker was developed for Alzheimer's clinical trials that combines cognitive and atrophy markers. Atrophy within specific brain regions was found to be closely related with impairment in cognitive domains of memory, language, and praxis. The proposed biomarker showed significantly better sensitivity in tracking progression of cognitive impairment than the ADAS-Cog in simulated trials and a real world problem. The biomarker also improved the selection of MCI patients (78.8±4.9% specificity at 80% sensitivity) that will evolve to Alzheimer's disease for clinical trials. The proposed biomarker provides a boost to the efficacy of clinical trials focused in the mild cognitive impairment (MCI) stage by significantly improving the sensitivity to detect treatment effects and improving the selection of MCI patients that will evolve to Alzheimer's disease. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Fetal alcohol syndrome, chemo-biology and OMICS: ethanol effects on vitamin metabolism during neurodevelopment as measured by systems biology analysis.

PubMed

Feltes, Bruno César; de Faria Poloni, Joice; Nunes, Itamar José Guimarães; Bonatto, Diego

2014-06-01

Fetal alcohol syndrome (FAS) is a prenatal disease characterized by fetal morphological and neurological abnormalities originating from exposure to alcohol. Although FAS is a well-described pathology, the molecular mechanisms underlying its progression are virtually unknown. Moreover, alcohol abuse can affect vitamin metabolism and absorption, although how alcohol impairs such biochemical pathways remains to be elucidated. We employed a variety of systems chemo-biology tools to understand the interplay between ethanol metabolism and vitamins during mouse neurodevelopment. For this purpose, we designed interactomes and employed transcriptomic data analysis approaches to study the neural tissue of Mus musculus exposed to ethanol prenatally and postnatally, simulating conditions that could lead to FAS development at different life stages. Our results showed that FAS can promote early changes in neurotransmitter release and glutamate equilibrium, as well as an abnormal calcium influx that can lead to neuroinflammation and impaired neurodifferentiation, both extensively connected with vitamin action and metabolism. Genes related to retinoic acid, niacin, vitamin D, and folate metabolism were underexpressed during neurodevelopment and appear to contribute to neuroinflammation progression and impaired synapsis. Our results also indicate that genes coding for tubulin, tubulin-associated proteins, synapse plasticity proteins, and proteins related to neurodifferentiation are extensively affected by ethanol exposure. Finally, we developed a molecular model of how ethanol can affect vitamin metabolism and impair neurodevelopment.

Vision-based gait impairment analysis for aided diagnosis.

PubMed

Ortells, Javier; Herrero-Ezquerro, María Trinidad; Mollineda, Ramón A

2018-02-12

Gait is a firsthand reflection of health condition. This belief has inspired recent research efforts to automate the analysis of pathological gait, in order to assist physicians in decision-making. However, most of these efforts rely on gait descriptions which are difficult to understand by humans, or on sensing technologies hardly available in ambulatory services. This paper proposes a number of semantic and normalized gait features computed from a single video acquired by a low-cost sensor. Far from being conventional spatio-temporal descriptors, features are aimed at quantifying gait impairment, such as gait asymmetry from several perspectives or falling risk. They were designed to be invariant to frame rate and image size, allowing cross-platform comparisons. Experiments were formulated in terms of two databases. A well-known general-purpose gait dataset is used to establish normal references for features, while a new database, introduced in this work, provides samples under eight different walking styles: one normal and seven impaired patterns. A number of statistical studies were carried out to prove the sensitivity of features at measuring the expected pathologies, providing enough evidence about their accuracy. Graphical Abstract Graphical abstract reflecting main contributions of the manuscript: at the top, a robust, semantic and easy-to-interpret feature set to describe impaired gait patterns; at the bottom, a new dataset consisting of video-recordings of a number of volunteers simulating different patterns of pathological gait, where features were statistically assessed.

Robotic/virtual reality intervention program individualized to meet the specific sensorimotor impairments of an individual patient: a case study.

PubMed

Fluet, Gerard G; Merians, Alma S; Qiu, Qinyin; Saleh, Soha; Ruano, Viviana; Delmonico, Andrea R; Adamovich, Sergei V

2014-09-01

A majority of studies examining repetitive task practice facilitated by robots for the treatment of upper extremity paresis utilize standardized protocols applied to large groups. This study will describe a virtually simulated, robot-based intervention customized to match the goals and clinical presentation of a gentleman with upper extremity hemiparesis secondary to stroke. MP, the subject of this case, is an 85-year-old man with left hemiparesis secondary to an intracerebral hemorrhage 5 years prior to examination. Outcomes were measured before and after a 1-month period of home therapy and after a 1-month virtually simulated, robotic intervention. The intervention was designed to address specific impairments identified during his PT examination. When necessary, activities were modified based on MP's response to his first week of treatment. MP's home training program produced a 3-s decline in Wolf Motor Function Test (WMFT) time and a 5-s improvement in Jebsen Test of Hand Function (JTHF) time. He demonstrated an additional 35-s improvement in JTHF and an additional 44-s improvement in WMFT subsequent to the robotic training intervention. A 24-h activity measurement and the Hand and Activities of Daily Living scales of the Stroke Impact Scale improved following the robotic intervention. Based on his responses to training we feel that we have established that a customized program of virtually simulated, robotically facilitated rehabilitation was feasible and resulted in larger improvements than an intensive home training program in several measurements of upper extremity function in our patient with chronic hemiparesis.

Renal contrast-enhanced MR angiography: timing errors and accurate depiction of renal artery origins.

PubMed

Schmidt, Maria A; Morgan, Robert

2008-10-01

To investigate bolus timing artifacts that impair depiction of renal arteries at contrast material-enhanced magnetic resonance (MR) angiography and to determine the effect of contrast agent infusion rates on artifact generation. Renal contrast-enhanced MR angiography was simulated for a variety of infusion schemes, assuming both correct and incorrect timing between data acquisition and contrast agent injection. In addition, the ethics committee approved the retrospective evaluation of clinical breath-hold renal contrast-enhanced MR angiographic studies obtained with automated detection of contrast agent arrival. Twenty-two studies were evaluated for their ability to depict the origin of renal arteries in patent vessels and for any signs of timing errors. Simulations showed that a completely artifactual stenosis or an artifactual overestimation of an existing stenosis at the renal artery origin can be caused by timing errors of the order of 5 seconds in examinations performed with contrast agent infusion rates compatible with or higher than those of hand injections. Lower infusion rates make the studies more likely to accurately depict the origin of the renal arteries. In approximately one-third of all clinical examinations, different contrast agent uptake rates were detected on the left and right sides of the body, and thus allowed us to confirm that it is often impossible to optimize depiction of both renal arteries. In three renal arteries, a signal void was found at the origin in a patent vessel, and delayed contrast agent arrival was confirmed. Computer simulations and clinical examinations showed that timing errors impair the accurate depiction of renal artery origins. (c) RSNA, 2008.

Mechanism underlying impaired cardiac pacemaking rhythm during ischemia: A simulation study

NASA Astrophysics Data System (ADS)

Bai, Xiangyun; Wang, Kuanquan; Yuan, Yongfeng; Li, Qince; Dobrzynski, Halina; Boyett, Mark R.; Hancox, Jules C.; Zhang, Henggui

2017-09-01

Ischemia in the heart impairs function of the cardiac pacemaker, the sinoatrial node (SAN). However, the ionic mechanisms underlying the ischemia-induced dysfunction of the SAN remain elusive. In order to investigate the ionic mechanisms by which ischemia causes SAN dysfunction, action potential models of rabbit SAN and atrial cells were modified to incorporate extant experimental data of ischemia-induced changes to membrane ion channels and intracellular ion homeostasis. The cell models were incorporated into an anatomically detailed 2D model of the intact SAN-atrium. Using the multi-scale models, the functional impact of ischemia-induced electrical alterations on cardiac pacemaking action potentials (APs) and their conduction was investigated. The effects of vagal tone activity on the regulation of cardiac pacemaker activity in control and ischemic conditions were also investigated. The simulation results showed that at the cellular level ischemia slowed the SAN pacemaking rate, which was mainly attributable to the altered Na+-Ca2+ exchange current and the ATP-sensitive potassium current. In the 2D SAN-atrium tissue model, ischemia slowed down both the pacemaking rate and the conduction velocity of APs into the surrounding atrial tissue. Simulated vagal nerve activity, including the actions of acetylcholine in the model, amplified the effects of ischemia, leading to possible SAN arrest and/or conduction exit block, which are major features of the sick sinus syndrome. In conclusion, this study provides novel insights into understanding the mechanisms by which ischemia alters SAN function, identifying specific conductances as contributors to bradycardia and conduction block.

Visual-Vestibular Conflict Detection Depends on Fixation.

PubMed

Garzorz, Isabelle T; MacNeilage, Paul R

2017-09-25

Visual and vestibular signals are the primary sources of sensory information for self-motion. Conflict among these signals can be seriously debilitating, resulting in vertigo [1], inappropriate postural responses [2], and motion, simulator, or cyber sickness [3-8]. Despite this significance, the mechanisms mediating conflict detection are poorly understood. Here we model conflict detection simply as crossmodal discrimination with benchmark performance limited by variabilities of the signals being compared. In a series of psychophysical experiments conducted in a virtual reality motion simulator, we measure these variabilities and assess conflict detection relative to this benchmark. We also examine the impact of eye movements on visual-vestibular conflict detection. In one condition, observers fixate a point that is stationary in the simulated visual environment by rotating the eyes opposite head rotation, thereby nulling retinal image motion. In another condition, eye movement is artificially minimized via fixation of a head-fixed fixation point, thereby maximizing retinal image motion. Visual-vestibular integration performance is also measured, similar to previous studies [9-12]. We observe that there is a tradeoff between integration and conflict detection that is mediated by eye movements. Minimizing eye movements by fixating a head-fixed target leads to optimal integration but highly impaired conflict detection. Minimizing retinal motion by fixating a scene-fixed target improves conflict detection at the cost of impaired integration performance. The common tendency to fixate scene-fixed targets during self-motion [13] may indicate that conflict detection is typically a higher priority than the increase in precision of self-motion estimation that is obtained through integration. Copyright © 2017 Elsevier Ltd. All rights reserved.

Allosteric dynamics of SAMHD1 studied by molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Patra, K. K.; Bhattacharya, A.; Bhattacharya, S.

2016-10-01

SAMHD1 is a human cellular enzyme that blocks HIV-1 infection in myeloid cells and non-cycling CD4+T cells. The enzyme is an allosterically regulated triphosphohydrolase that modulates the level of cellular dNTP. The virus restriction is attributed to the lowering of the pool of dNTP in the cell to a point where reverse-transcription is impaired. Mutations in SAMHD1 are also implicated in Aicardi-Goutieres syndrome. A mechanistic understanding of the allosteric activation of the enzyme is still elusive. We have performed molecular dynamics simulations to examine the allosteric site dynamics of the protein and to examine the connection between the stability of the tetrameric complex and the Allosite occupancy.

Assessment of Robotic Patient Simulators for Training in Manual Physical Therapy Examination Techniques

PubMed Central

Ishikawa, Shun; Okamoto, Shogo; Isogai, Kaoru; Akiyama, Yasuhiro; Yanagihara, Naomi; Yamada, Yoji

2015-01-01

Robots that simulate patients suffering from joint resistance caused by biomechanical and neural impairments are used to aid the training of physical therapists in manual examination techniques. However, there are few methods for assessing such robots. This article proposes two types of assessment measures based on typical judgments of clinicians. One of the measures involves the evaluation of how well the simulator presents different severities of a specified disease. Experienced clinicians were requested to rate the simulated symptoms in terms of severity, and the consistency of their ratings was used as a performance measure. The other measure involves the evaluation of how well the simulator presents different types of symptoms. In this case, the clinicians were requested to classify the simulated resistances in terms of symptom type, and the average ratios of their answers were used as performance measures. For both types of assessment measures, a higher index implied higher agreement among the experienced clinicians that subjectively assessed the symptoms based on typical symptom features. We applied these two assessment methods to a patient knee robot and achieved positive appraisals. The assessment measures have potential for use in comparing several patient simulators for training physical therapists, rather than as absolute indices for developing a standard. PMID:25923719

Notes From the Field: Secondary Task Precision for Cognitive Load Estimation During Virtual Reality Surgical Simulation Training.

PubMed

Rasmussen, Sebastian R; Konge, Lars; Mikkelsen, Peter T; Sørensen, Mads S; Andersen, Steven A W

2016-03-01

Cognitive load (CL) theory suggests that working memory can be overloaded in complex learning tasks such as surgical technical skills training, which can impair learning. Valid and feasible methods for estimating the CL in specific learning contexts are necessary before the efficacy of CL-lowering instructional interventions can be established. This study aims to explore secondary task precision for the estimation of CL in virtual reality (VR) surgical simulation and also investigate the effects of CL-modifying factors such as simulator-integrated tutoring and repeated practice. Twenty-four participants were randomized for visual assistance by a simulator-integrated tutor function during the first 5 of 12 repeated mastoidectomy procedures on a VR temporal bone simulator. Secondary task precision was found to be significantly lower during simulation compared with nonsimulation baseline, p < .001. Contrary to expectations, simulator-integrated tutoring and repeated practice did not have an impact on secondary task precision. This finding suggests that even though considerable changes in CL are reflected in secondary task precision, it lacks sensitivity. In contrast, secondary task reaction time could be more sensitive, but requires substantial postprocessing of data. Therefore, future studies on the effect of CL modifying interventions should weigh the pros and cons of the various secondary task measurements. © The Author(s) 2015.

Driving simulator sickness: Impact on driving performance, influence of blood alcohol concentration, and effect of repeated simulator exposures.

PubMed

Helland, Arne; Lydersen, Stian; Lervåg, Lone-Eirin; Jenssen, Gunnar D; Mørland, Jørg; Slørdal, Lars

2016-09-01

Simulator sickness is a major obstacle to the use of driving simulators for research, training and driver assessment purposes. The purpose of the present study was to investigate the possible influence of simulator sickness on driving performance measures such as standard deviation of lateral position (SDLP), and the effect of alcohol or repeated simulator exposure on the degree of simulator sickness. Twenty healthy male volunteers underwent three simulated driving trials of 1h's duration with a curvy rural road scenario, and rated their degree of simulator sickness after each trial. Subjects drove sober and with blood alcohol concentrations (BAC) of approx. 0.5g/L and 0.9g/L in a randomized order. Simulator sickness score (SSS) did not influence the primary outcome measure SDLP. Higher SSS significantly predicted lower average speed and frequency of steering wheel reversals. These effects seemed to be mitigated by alcohol. Higher BAC significantly predicted lower SSS, suggesting that alcohol inebriation alleviates simulator sickness. The negative relation between the number of previous exposures to the simulator and SSS was not statistically significant, but is consistent with habituation to the sickness-inducing effects, as shown in other studies. Overall, the results suggest no influence of simulator sickness on SDLP or several other driving performance measures. However, simulator sickness seems to cause test subjects to drive more carefully, with lower average speed and fewer steering wheel reversals, hampering the interpretation of these outcomes as measures of driving impairment and safety. BAC and repeated simulator exposures may act as confounding variables by influencing the degree of simulator sickness in experimental studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Brief Report: Examining Driving Behavior in Young Adults with High Functioning Autism Spectrum Disorders--A Pilot Study Using a Driving Simulation Paradigm

ERIC Educational Resources Information Center

Reimer, Bryan; Fried, Ronna; Mehler, Bruce; Joshi, Gagan; Bolfek, Anela; Godfrey, Kathryn M.; Zhao, Nan; Goldin, Rachel; Biederman, Joseph

2013-01-01

Although it is speculated that impairments associated with autism spectrum disorder (ASD) will adversely affect driving performance, little is known about the actual extent and nature of the presumed deficits. Ten males (18-24 years of age) with a diagnosis of high functioning autism and 10 age matched community controls were recruited for a…

Brain Transcriptome Profiles in Mouse Model Simulating Features of Post-traumatic Stress Disorder

DTIC Science & Technology

2015-02-28

comorbid-related signaling pathways indicate the pervasive and multisystem effects of aggressor exposure in mice, potentially mirroring the pathologic...11,12]. Impaired extinction of fear- potentiated startle and en- hanced cue conditioning in these brain regions (of trau- matized patients and animal...lead to either a long-term synap- tic potentiation (LTP) increase in synaptic strength and in- crease in excitatory post-synaptic potential

Drivers who self-estimate lower blood alcohol concentrations are riskier drivers after drinking.

PubMed

Laude, Jennifer R; Fillmore, Mark T

2016-04-01

Alcohol increases the tendency for risky driving in some individuals but not others. Little is known about the factors underlying this individual difference. Studies find that those who underestimate their blood alcohol concentration (BAC) following a dose of alcohol tend to be more impulsive and report greater willingness to drive after drinking than those who estimate their BACs to be greater than their actual BAC. BAC underestimation could contribute to risky driving behavior following alcohol as such drivers might perceive little impairment in their driving ability and thus no need for caution. This study was designed to test the relationship between drivers' BAC estimations following a dose of alcohol or a placebo and the degree of risky driving they displayed during a simulated driving test. Forty adult drivers performed a simulated driving test and estimated their blood alcohol concentration after receiving a dose of alcohol (0.65 g/kg for men and 0.56 g/kg for women) or a placebo. Alcohol increased risk-taking and impaired driving skill. Those who estimated their BAC to be lower were the riskiest drivers following both alcohol and placebo. The tendency to estimate lower BACs could support a series of high-risk decisions, regardless of one's actual BAC. This could include the decision to drive after drinking.

Can we continue to ignore gender differences in performance on simulation trainers?

PubMed

Thorson, Chad M; Kelly, Jason P; Forse, R Armour; Turaga, Kiran K

2011-05-01

There are differences between the genders in their innate performances on simulation trainers, which may impair accurate assessment of psychomotor skills. The performance of fourth-year students with no exposure to the Minimally Invasive Surgical Trainer compared based on gender, and other psychomotor skills. Our study included 16 male and 16 female students. After adjusting for choice of medical specialty (P<.001), current video game use (P=.6), and experience in the operating room (P=.4), female sex was an independent factor for worse performance (P=.04) in multivariate models. Women took more time than men (P<.01) and made more errors (29 versus 25 on 3 reps, P<.01). Among medical students with no previous exposure to laparoscopic trainers, female students perform worse than male students after adjusting for confounding factors. This difference must be recognized by training programs while using simulators for training and evaluation.

The Effects of Dextromethorphan on Driving Performance and the Standardized Field Sobriety Test.

PubMed

Perry, Paul J; Fredriksen, Kristian; Chew, Stephanie; Ip, Eric J; Lopes, Ingrid; Doroudgar, Shadi; Thomas, Kelan

2015-09-01

Dextromethorphan (DXM) is abused most commonly among adolescents as a recreational drug to generate a dissociative experience. The objective of the study was to assess driving with and without DXM ingestion. The effects of one-time maximum daily doses of DXM 120 mg versus a guaifenesin 400 mg dose were compared among 40 healthy subjects using a crossover design. Subjects' ability to drive was assessed by their performance in a driving simulator (STISIM® Drive driving simulator software) and by conducting a standardized field sobriety test (SFST) administered 1-h postdrug administration. The one-time dose of DXM 120 mg did not demonstrate driving impairment on the STISIM® Drive driving simulator or increase SFST failures compared to guaifenesin 400 mg. Doses greater than the currently recommended maximum daily dose of 120 mg are necessary to perturb driving behavior. © 2015 American Academy of Forensic Sciences.

Virtual reality, disability and rehabilitation.

PubMed

Wilson, P N; Foreman, N; Stanton, D

1997-06-01

Virtual reality, or virtual environment computer technology, generates simulated objects and events with which people can interact. Existing and potential applications for this technology in the field of disability and rehabilitation are discussed. The main benefits identified for disabled people are that they can engage in a range of activities in a simulator relatively free from the limitations imposed by their disability, and they can do so in safety. Evidence that the knowledge and skills acquired by disabled individuals in simulated environments can transfer to the real world is presented. In particular, spatial information and life skills learned in a virtual environment have been shown to transfer to the real world. Applications for visually impaired people are discussed, and the potential for medical interventions and the assessment and treatment of neurological damage are considered. Finally some current limitations of the technology, and ethical concerns in relation to disability, are discussed.

Simulation and analysis on ultrasonic testing for the cement grouting defects of the corrugated pipe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qingbang, Han; Ling, Chen; Changping, Zhu

2014-02-18

The defects exist in the cement grouting process of prestressed corrugated pipe may directly impair the bridge safety. In this paper, sound fields propagation in concrete structures with corrugated pipes and the influence of various different defects are simulated and analyzed using finite element method. The simulation results demonstrate a much complex propagation characteristic due to multiple reflection, refraction and scattering, where the scattering signals caused by metal are very strong, while the signals scattered by an air bubble are weaker. The influence of defect both in time and frequency domain are found through deconvolution treatment. In the time domain,more » the deconvolution signals correspond to larger defect display a larger head wave amplitude and shorter arrive time than those of smaller defects; in the frequency domain, larger defect also shows a stronger amplitude, lower center frequency and lower cutoff frequency.« less

Dopamine, reward learning, and active inference

PubMed Central

FitzGerald, Thomas H. B.; Dolan, Raymond J.; Friston, Karl

2015-01-01

Temporal difference learning models propose phasic dopamine signaling encodes reward prediction errors that drive learning. This is supported by studies where optogenetic stimulation of dopamine neurons can stand in lieu of actual reward. Nevertheless, a large body of data also shows that dopamine is not necessary for learning, and that dopamine depletion primarily affects task performance. We offer a resolution to this paradox based on an hypothesis that dopamine encodes the precision of beliefs about alternative actions, and thus controls the outcome-sensitivity of behavior. We extend an active inference scheme for solving Markov decision processes to include learning, and show that simulated dopamine dynamics strongly resemble those actually observed during instrumental conditioning. Furthermore, simulated dopamine depletion impairs performance but spares learning, while simulated excitation of dopamine neurons drives reward learning, through aberrant inference about outcome states. Our formal approach provides a novel and parsimonious reconciliation of apparently divergent experimental findings. PMID:26581305

Dopamine, reward learning, and active inference.

PubMed

FitzGerald, Thomas H B; Dolan, Raymond J; Friston, Karl

2015-01-01

Temporal difference learning models propose phasic dopamine signaling encodes reward prediction errors that drive learning. This is supported by studies where optogenetic stimulation of dopamine neurons can stand in lieu of actual reward. Nevertheless, a large body of data also shows that dopamine is not necessary for learning, and that dopamine depletion primarily affects task performance. We offer a resolution to this paradox based on an hypothesis that dopamine encodes the precision of beliefs about alternative actions, and thus controls the outcome-sensitivity of behavior. We extend an active inference scheme for solving Markov decision processes to include learning, and show that simulated dopamine dynamics strongly resemble those actually observed during instrumental conditioning. Furthermore, simulated dopamine depletion impairs performance but spares learning, while simulated excitation of dopamine neurons drives reward learning, through aberrant inference about outcome states. Our formal approach provides a novel and parsimonious reconciliation of apparently divergent experimental findings.

Modeling accumulations of particles in lung during chronic inhalation exposures that lead to impaired clearance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolff, R.K.; Griffith, W.C. Jr.; Cuddihy, R.G.

Chronic inhalation of insoluble particles of low toxicity that produce substantial lung burdens of particles, or inhalation of particles that are highly toxic to the lung, can impair clearance. This report describes model calculations of accumulations in lung of inhaled low-toxicity diesel exhaust soot and high-toxicity Ga2O3 particles. Lung burdens of diesel soot were measured periodically during a 24-mo exposure to inhaled diesel exhaust at soot concentrations of 0, 0.35, 3.5, and 7 mg m-3, 7 h d-1, 5 d wk-1. Lung burdens of Ga2O3 were measured for 1 y after a 4-wk exposure to 23 mg Ga2O3 m-3, 2more » h d-1, 5 d wk-1. Lung burdens of Ga2O3 were measured for 1 y both studies using inhaled radiolabeled tracer particles. Simulation models fit the observed lung burdens of diesel soot in rats exposed to the 3.5- and 7-mg m-3 concentrations of soot only if it was assumed that clearance remained normal for several months, then virtually stopped. Impaired clearance from high-toxicity particles occurred early after accumulations of a low burden, but that from low-toxicity particles was evident only after months of exposure, when high burdens had accumulated in lung. The impairment in clearances of Ga2O3 particles and radiolabeled tracers was similar, but the impairment in clearance of diesel soot and radiolabeled tracers differed in magnitude. This might have been related to differences in particle size and composition between the tracers and diesel soot. Particle clearance impairment should be considered both in the design of chronic exposures of laboratory animals to inhaled particles and in extrapolating the results to people.« less

Renal and cardiovascular responses to water immersion in trained runners and swimmers

NASA Technical Reports Server (NTRS)

Convertino, V. A.; Tatro, D. L.; Rogan, R. B.

1993-01-01

The purpose of this study was to determine if fluid-electrolyte, renal, hormonal, and cardiovascular responses during and after multi-hour water immersion were associated with aerobic training. Additionally, we compared these responses in those who trained in a hypogravic versus a 1-g environment. Seventeen men comprised three similarly aged groups: six long-distance runners, five competitive swimmers, and six untrained control subjects. Each subject underwent 5 h of immersion in water [mean (SE)] 36.0 (0.5) degrees C to the neck. Immediately before and at each hour of immersion, blood and urine samples were collected and analyzed for sodium (Na), potassium, osmolality, and creatinine (Cr). Plasma antidiuretic hormone and aldosterone were also measured. Hematocrits were used to calculate relative changes in plasma volume (% delta Vpl). Heart rate response to submaximal cycle ergometer exercise (35% peak oxygen uptake) was measured before and after water immersion. Water immersion induced significant increases in urine flow, Na clearance (CNa), and a 3-5% decrease in Vpl. Urine flow during immersion was greater (P < 0.05) in runners [2.4 (0.4) ml.min-1] compared to controls [1.3 (0.1) ml.min-1]. However, % delta Vpl, CCr, CNa and CH2O during immersion were not different (P > 0.05) between runners, swimmers, and controls. After 5 h of immersion, there was an increase (P < 0.05) in submaximal exercise heart rate of 9 (3) and 10 (3) beats.min-1 in both runners and controls, respectively, but no change (P > 0.05) was observed in swimmers.(ABSTRACT TRUNCATED AT 250 WORDS).

Varying whole body vibration amplitude differentially affects tendon and ligament structural and material properties

PubMed Central

Keller, Benjamin V.; Davis, Matthew L.; Thompson, William R.; Dahners, Laurence E.; Weinhold, Paul S.

2014-01-01

Whole Body Vibration (WBV) is becoming increasingly popular for helping to maintain bone mass and strengthening muscle. Vibration regimens optimized for bone maintenance often operate at hypogravity levels (<1 G) and regimens for muscle strengthening often employ hypergravity (>1 G) vibrations. The effect of vibratory loads on tendon and ligament properties is unclear though excessive vibrations may be injurious. Our objective was to evaluate how tendon gene expression and the mechanical/histological properties of tendon and ligament were affected in response to WBV in the following groups: no vibration, low vibration (0.3 G peak-to-peak), and high vibration (2 G peak-to-peak). Rats were vibrated for 20 min a day, 5 days a week, for 5 weeks. Upon sacrifice, the medial collateral ligament (MCL), patellar tendon (PT), and the Achilles Tendon (AT) were isolated with insertion sites intact. All tissues were tensile tested to determine structural and material properties or used for histology. Patellar tendon was also subjected to quantitative RT-PCR to evaluate expression of anabolic and catabolic genes. No differences in biomechanical data between the control and the low vibration groups were found. There was evidence of significant weakness in the MCL with high vibration, but no significant effect on the PT or AT. Histology of the MCL and PT showed a hypercellular tissue response and some fiber disorganization with high vibration. High vibration caused an increase in collagen expression and a trend for an increase in IGF-1 expression suggesting a potential anabolic response to prevent tendon overuse injury. PMID:23623311

Gravity as a biochemical determinant

NASA Technical Reports Server (NTRS)

Siegel, S. M.

1979-01-01

The existence of obvious morphological and physiological changes in living systems exposed to altered gravity immediately informs us that prior changes have taken place in the chemistry of exposed cells, tissues and organs. These changes include transients that return more or less promptly to the norm when the system is restored to the terrestrial g-field. For example, altered serum hormone and electrolyte levels in man, which appear to reflect successful adaptation to the conditions of orbital weightlessness, disappear shortly after return to Earth. Other changes--in mineral and protein constituents of the skeletal system in man, and cell wall composition in plants--are more persistent or even permanent. Hypogravitational departures from the norm include not only "weightlessness" as achieved in orbit, but also experimental modes of compensation, on the clinostat or by flotation. These techniques are useful in the study of hypogravity but cannot replace fully the weightless environment. Plant ethylene and peroxidase both increase under orbital, clinostat and/or flotation conditions whereas 3-phosphoglyceraldehyde-dehydrogenase increases under orbital but not clinostat conditions; cytochrome reductase and malic dehydrogenase levels are affected by the clinostat, but not by actual weightless conditions. How do the altered organismal biochemistries induced by the centrifuge and the clinostat relate to one another? Does gravity operate on living systems as a continuous variable from 0 to superterrestrial values, or do deviations from g(earth) generate non-uniform, discontinuous stress responses, irrespective of sign? In plants, measurements of wall lignin content and peroxidase activity yield opposite answers. Given the limited data so far available we will consider the meaning of these contradictions.

Disease progression model for Clinical Dementia Rating–Sum of Boxes in mild cognitive impairment and Alzheimer’s subjects from the Alzheimer’s Disease Neuroimaging Initiative

PubMed Central

Samtani, Mahesh N; Raghavan, Nandini; Novak, Gerald; Nandy, Partha; Narayan, Vaibhav A

2014-01-01

Background The objective of this analysis was to develop a nonlinear disease progression model, using an expanded set of covariates that captures the longitudinal Clinical Dementia Rating Scale–Sum of Boxes (CDR–SB) scores. These were derived from the Alzheimer’s Disease Neuroimaging Initiative ADNI-1 study, of 301 Alzheimer’s disease and mild cognitive impairment patients who were followed for 2–3 years. Methods The model describes progression rate and baseline disease score as a function of covariates. The covariates that were tested fell into five groups: a) hippocampal volume; b) serum and cerebrospinal fluid (CSF) biomarkers; c) demographics and apolipoprotein Epsilon 4 (ApoE4) allele status; d) baseline cognitive tests; and e) disease state and comedications. Results Covariates associated with baseline disease severity were disease state, hippocampal volume, and comedication use. Disease progression rate was influenced by baseline CSF biomarkers, Trail-Making Test part A score, delayed logical memory test score, and current level of impairment as measured by CDR–SB. The rate of disease progression was dependent on disease severity, with intermediate scores around the inflection point score of 10 exhibiting high disease progression rate. The CDR–SB disease progression rate in a typical patient, with late mild cognitive impairment and mild Alzheimer’s disease, was estimated to be approximately 0.5 and 1.4 points/year, respectively. Conclusions In conclusion, this model describes disease progression in terms of CDR–SB changes in patients and its dependency on novel covariates. The CSF biomarkers included in the model discriminate mild cognitive impairment subjects as progressors and nonprogressors. Therefore, the model may be utilized for optimizing study designs, through patient population enrichment and clinical trial simulations. PMID:24926196

Developing Critical Loads of acidity for streams in the Great Smoky Mountains National Park, using PnET-BGC model

NASA Astrophysics Data System (ADS)

Fakhraei, H.

2015-12-01

Acid deposition has impaired acid-sensitive streams and reduced aquatic biotic integrity in Great Smoky Mountains National Park (GRSM) by decreasing pH and acid neutralizing capacity (ANC). Twelve streams in GRSM are listed by the state of Tennessee as impaired due to low stream pH (pH<6.0) under Section 303(d) of the Clean Water Act. A dynamic biogeochemical model, PnET-BGC, was used to evaluate past, current and potential future changes in soil and water chemistry of watersheds of GRSM in response to changes in acid deposition. Calibrating 30 stream-watersheds in GRSM (including 12 listed impaired streams) to the long-term stream chemistry observations, the model was parameterized for the Park. The calibrated model was used to evaluate the level of atmospheric deposition above which harmful effects occur, known as "critical loads", for individual study watersheds. Estimated critical loads and exceedances (levels of deposition above the critical load) of atmospheric sulfur and nitrogen deposition were depicted through geographic information system maps. Accuracy of model simulations in the presence of uncertainties in the estimated model parameters and inputs was assessed using three uncertainty and sensitivity techniques.

Hippocampus-Dependent Goal Localization by Head-Fixed Mice in Virtual Reality.

PubMed

Sato, Masaaki; Kawano, Masako; Mizuta, Kotaro; Islam, Tanvir; Lee, Min Goo; Hayashi, Yasunori

2017-01-01

The demonstration of the ability of rodents to navigate in virtual reality (VR) has made it an important behavioral paradigm for studying spatially modulated neuronal activity in these animals. However, their behavior in such simulated environments remains poorly understood. Here, we show that encoding and retrieval of goal location memory in mice head-fixed in VR depends on the postsynaptic scaffolding protein Shank2 and the dorsal hippocampus. In our newly developed virtual cued goal location task, a head-fixed mouse moves from one end of a virtual linear track to seek rewards given at a target location along the track. The mouse needs to visually recognize the target location and stay there for a short period of time to receive the reward. Transient pharmacological blockade of fast glutamatergic synaptic transmission in the dorsal hippocampus dramatically and reversibly impaired performance of this task. Encoding and updating of virtual cued goal location memory was impaired in mice deficient in the postsynaptic scaffolding protein Shank2, a mouse model of autism that exhibits impaired spatial learning in a real environment. These results highlight the crucial roles of the dorsal hippocampus and postsynaptic protein complexes in spatial learning and navigation in VR.

Hippocampus-Dependent Goal Localization by Head-Fixed Mice in Virtual Reality

PubMed Central

Kawano, Masako; Mizuta, Kotaro; Islam, Tanvir; Lee, Min Goo; Hayashi, Yasunori

2017-01-01

Abstract The demonstration of the ability of rodents to navigate in virtual reality (VR) has made it an important behavioral paradigm for studying spatially modulated neuronal activity in these animals. However, their behavior in such simulated environments remains poorly understood. Here, we show that encoding and retrieval of goal location memory in mice head-fixed in VR depends on the postsynaptic scaffolding protein Shank2 and the dorsal hippocampus. In our newly developed virtual cued goal location task, a head-fixed mouse moves from one end of a virtual linear track to seek rewards given at a target location along the track. The mouse needs to visually recognize the target location and stay there for a short period of time to receive the reward. Transient pharmacological blockade of fast glutamatergic synaptic transmission in the dorsal hippocampus dramatically and reversibly impaired performance of this task. Encoding and updating of virtual cued goal location memory was impaired in mice deficient in the postsynaptic scaffolding protein Shank2, a mouse model of autism that exhibits impaired spatial learning in a real environment. These results highlight the crucial roles of the dorsal hippocampus and postsynaptic protein complexes in spatial learning and navigation in VR. PMID:28484738

Probabilistic Modeling of Intracranial Pressure Effects on Optic Nerve Biomechanics

NASA Technical Reports Server (NTRS)

Ethier, C. R.; Feola, Andrew J.; Raykin, Julia; Myers, Jerry G.; Nelson, Emily S.; Samuels, Brian C.

2016-01-01

Altered intracranial pressure (ICP) is involved/implicated in several ocular conditions: papilledema, glaucoma and Visual Impairment and Intracranial Pressure (VIIP) syndrome. The biomechanical effects of altered ICP on optic nerve head (ONH) tissues in these conditions are uncertain but likely important. We have quantified ICP-induced deformations of ONH tissues, using finite element (FE) and probabilistic modeling (Latin Hypercube Simulations (LHS)) to consider a range of tissue properties and relevant pressures.

Nonlinear filter based decision feedback equalizer for optical communication systems.

PubMed

Han, Xiaoqi; Cheng, Chi-Hao

2014-04-07

Nonlinear impairments in optical communication system have become a major concern of optical engineers. In this paper, we demonstrate that utilizing a nonlinear filter based Decision Feedback Equalizer (DFE) with error detection capability can deliver a better performance compared with the conventional linear filter based DFE. The proposed algorithms are tested in simulation using a coherent 100 Gb/sec 16-QAM optical communication system in a legacy optical network setting.

Simulating the Pattern of Right-Hemisphere-Damaged Patients for the Processing of the Alternative Metaphorical Meanings of Words: Evidence in Favor of a Cognitive Resources Hypothesis

ERIC Educational Resources Information Center

Monetta, Laura; Ouellet-Plamondon, Clairelaine; Joanette, Yves

2006-01-01

Lately, many studies have suggested that communication impairments in brain-damaged individuals might be explained--at least in part--in terms of cognitive resource allocation. Reproducing a clinical pattern in normal subjects by using a dual-task treatment might be a way of evaluating the role of cognitive resources in the right hemisphere's…

Functional performance testing for power and return to sports.

PubMed

Manske, Robert; Reiman, Michael

2013-05-01

Functional performance testing of athletes can determine physical limitations that may affect sporting activities. Optimal functional performance testing simulates the athlete's activity. A Medline search from 1960 to 2012 was implemented with the keywords functional testing, functional impairment testing, and functional performance testing in the English language. Each author also undertook independent searches of article references. Functional performance tests can bridge the gap between general physical tests and full, unrestricted athletic activity.

Watershed modeling of dissolved oxygen and biochemical oxygen demand using a hydrological simulation Fortran program.

PubMed

Liu, Zhijun; Kieffer, Janna M; Kingery, William L; Huddleston, David H; Hossain, Faisal

2007-11-01

Several inland water bodies in the St. Louis Bay watershed have been identified as being potentially impaired due to low level of dissolved oxygen (DO). In order to calculate the total maximum daily loads (TMDL), a standard watershed model supported by U.S. Environmental Protection Agency, Hydrological Simulation Program Fortran (HSPF), was used to simulate water temperature, DO, and bio-chemical oxygen demand (BOD). Both point and non-point sources of BOD were included in watershed modeling. The developed model was calibrated at two time periods: 1978 to 1986 and 2000 to 2001 with simulated DO closely matched the observed data and captured the seasonal variations. The model represented the general trend and average condition of observed BOD. Water temperature and BOD decay are the major factors that affect DO simulation, whereas nutrient processes, including nitrification, denitrification, and phytoplankton cycle, have slight impacts. The calibrated water quality model provides a representative linkage between the sources of BOD and in-stream DO\\BOD concentrations. The developed input parameters in this research could be extended to similar coastal watersheds for TMDL determination and Best Management Practice (BMP) evaluation.

Stability of simulated flight path control at +3 Gz in a human centrifuge.

PubMed

Guardiera, Simon; Dalecki, Marc; Bock, Otmar

2010-04-01

Earlier studies have shown that naïve subjects and experienced jet pilots produce exaggerated manual forces when exposed to increased acceleration (+Gz). This study was designed to evaluate whether this exaggeration affects the stability of simulated flight path control. We evaluated naïve subjects' performance in a flight simulator which either remained stationary (+1 Gz), or rotated to induce an acceleration in accordance to the simulated flight path with a mean acceleration of about +3 Gz. In either case, subjects were requested to produce a series of altitude changes in pursuit of a visual target airplane. Resulting flight paths were analyzed to determine the largest oscillation after an altitude change (Oscillation) and the mean deviation between subject and target flight path (Tracking Error). Flight stability after an altitude change was degraded in +3 Gz compared to +1 Gz, as evidenced by larger Oscillations (+11%) and increased Tracking Errors (+80%). These deficits correlated significantly with subjects' +3 Gz deficits in a manual-force production task. We conclude that force exaggeration in +3 Gz may impair flight stability during simulated jet maneuvers in naïve subjects, most likely as a consequence of vestibular stimulation.

Effect of Horseback Riding Simulation Machine Training on Trunk Balance and Gait of Chronic Stroke Patients

PubMed Central

Kim, Hyungguen; Her, Jin Gang; Ko, Jooyeon

2014-01-01

[Purpose] The purpose of this study was to assess the effect of horseback riding simulation machine training on trunk balance and gait of patients with chronic stroke. [Subjects and Methods] The subjects were 20 patients hospitalized for treatment after being diagnosed with stroke. Horseback riding simulation training was provided for 30 minutes, 5 times a week, for 6 weeks. Trunk balance was assessed using the Trunk Impairment Scale (TIS) and a balance measuring device (Biorescue, RM ingenierie, France), and gait ability was measured using the Functional Gait Assessment (FGA) and a gait analyzer (GAITRite, CIR system Inc., USA). [Results] There were significant changes in movement area, distance and velocity of body sway as measured by the TIS and the balance measuring device, and in gait velocity, cadence, stride length and double limb support as measured by the FGA and gait analyzer. [Conclusion] Horseback riding simulation training improved the trunk balance and gait of chronic stroke patients. This present study provides preliminary objective data for future research, and useful clinical information for physical therapists using horseback riding simulation machines as a treatment modality for patients with chronic stroke. PMID:24567670

Walking simulator for evaluation of ophthalmic devices

NASA Astrophysics Data System (ADS)

Barabas, James; Woods, Russell L.; Peli, Eli

2005-03-01

Simulating mobility tasks in a virtual environment reduces risk for research subjects, and allows for improved experimental control and measurement. We are currently using a simulated shopping mall environment (where subjects walk on a treadmill in front of a large projected video display) to evaluate a number of ophthalmic devices developed at the Schepens Eye Research Institute for people with vision impairment, particularly visual field defects. We have conducted experiments to study subject's perception of "safe passing distance" when walking towards stationary obstacles. The subject's binary responses about potential collisions are analyzed by fitting a psychometric function, which gives an estimate of the subject's perceived safe passing distance, and the variability of subject responses. The system also enables simulations of visual field defects using head and eye tracking, enabling better understanding of the impact of visual field loss. Technical infrastructure for our simulated walking environment includes a custom eye and head tracking system, a gait feedback system to adjust treadmill speed, and a handheld 3-D pointing device. Images are generated by a graphics workstation, which contains a model with photographs of storefronts from an actual shopping mall, where concurrent validation experiments are being conducted.

Motor Imagery in Asperger Syndrome: Testing Action Simulation by the Hand Laterality Task

PubMed Central

Conson, Massimiliano; Mazzarella, Elisabetta; Frolli, Alessandro; Esposito, Dalila; Marino, Nicoletta; Trojano, Luigi; Massagli, Angelo; Gison, Giovanna; Aprea, Nellantonio; Grossi, Dario

2013-01-01

Asperger syndrome (AS) is a neurodevelopmental condition within the Autism Spectrum Disorders (ASD) characterized by specific difficulties in social interaction, communication and behavioural control. In recent years, it has been suggested that ASD is related to a dysfunction of action simulation processes, but studies employing imitation or action observation tasks provided mixed results. Here, we addressed action simulation processes in adolescents with AS by means of a motor imagery task, the classical hand laterality task (to decide whether a rotated hand image is left or right); mental rotation of letters was also evaluated. As a specific marker of action simulation in hand rotation, we assessed the so-called biomechanical effect, that is the advantage for judging hand pictures showing physically comfortable versus physically awkward positions. We found the biomechanical effect in typically-developing participants but not in participants with AS. Overall performance on both hand laterality and letter rotation tasks, instead, did not differ in the two groups. These findings demonstrated a specific alteration of motor imagery skills in AS. We suggest that impaired mental simulation and imitation of goal-less movements in ASD could be related to shared cognitive mechanisms. PMID:23894683

How safe are federal regulations on occupational alcohol use?

PubMed

Howland, Jonathan; Almeida, Alissa; Rohsenow, Damaris; Minsky, Sara; Greece, Jacey

2006-01-01

Current US federal regulations on occupational alcohol use for safety-sensitive jobs do not account for impairment from low doses of alcohol and next day effects of heavy drinking. Research on the effects of low doses of alcohol on neurocognitive and simulated occupational tasks suggests that the current per se level of these regulations is set too high. Research on the effects of heavy drinking on next-day neurocognitive and simulated occupational performance is mixed and suggests that further research is needed to determine the safety of current "bottle-to-throttle" times. Although low-dose and residual drinking effects may pose low relative risk for occupational error, the aggregate contribution of these exposures to workplace problems may be substantial, given the number of people exposed.

Acting with the future in mind is impaired in long-term opiate users.

PubMed

Terrett, Gill; Lyons, Amanda; Henry, Julie D; Ryrie, Clare; Suddendorf, Thomas; Rendell, Peter G

2017-01-01

Episodic foresight is a fundamental human capacity. It refers to the ability to simulate future situations and organise current actions accordingly. While there is some evidence that opiate users have a reduced capacity to imagine themselves in future situations, no study to date has assessed whether opiate users show deficits in the ability to take steps in the present in anticipation of future needs. In this study, we assessed whether this functional aspect of episodic foresight is impaired in chronic opiate users and the extent to which any deficits are associated with executive dysfunction. Participants were 33 long-term opiate users enrolled in an opiate substitution program and 34 controls. Relative to controls, the opiate users displayed significant impairment (medium effect size η 2 p  = 0.08) in the two behavioural measures of episodic foresight used (items acquired and items used in the VW Foresight task). Furthermore, executive functioning was associated with foresight ability, although this was restricted to items acquired, and the associations were generally stronger for the control group. These data provide important evidence suggesting that the functional aspect of episodic foresight is disrupted in long-term opiate users. While these deficits appear to have some links to impaired executive control, additional work is needed to gain a more complete understanding of the underlying cognitive and neural mechanisms involved. This, in turn, will have important implications for tailoring interventions with opiate users to maximise the likelihood of successful independent functioning.

High altitude memory impairment is due to neuronal apoptosis in hippocampus, cortex and striatum.

PubMed

Maiti, Panchanan; Singh, Shashi B; Mallick, Birendranath; Muthuraju, Sangu; Ilavazhagan, Govindasami

2008-12-01

Cognitive and neuropsychological functions have been impaired at high altitude and the effects depend on altitude and duration of stay. However, the neurobiological mechanism of this impairment is poorly understood especially exposure to different duration. Aim of the present study was to investigate the changes of behavior, biochemistry and morphology after exposure to different duration of hypobaric hypoxia. The rats were exposed continuously to a simulated high altitude of 6100m for 3, 7, 14 and 21 days in an animal decompression chamber. Spatial reference memory was tested by Morris water maze. The oxidative stress markers like free radicals, NO, lipid peroxidation, LDH activity and antioxidant systems like GSH, GSSG, GPx, GR, SOD were estimated from cortex, hippocampus and striatum. The morphological changes, neurodegeneration, DNA fragmentation and mode of cell death have also been studied. It was observed that the spatial reference memory was significantly affected after exposure to hypobaric hypoxia. Increased oxidative stress markers along with decreased effectiveness of antioxidant system were also observed in hypoxia-exposed animals. Further pyknotic, shrunken, tangle-like neurons were observed in all these regions after hypoxia and neurodegeneration, DNA fragmentation and apoptosis were also observed in all the three regions. But after 21 days of exposure, the spatial memory was improved along with improvement of antioxidant activities. Our result suggests that the apoptotic death may be involved in HA-induced memory impairment and after 7 days of exposure the effect was more pronounced but after 21 days of exposure recovery was observed.

The value of Bayes' theorem for interpreting abnormal test scores in cognitively healthy and clinical samples.

PubMed

Gavett, Brandon E

2015-03-01

The base rates of abnormal test scores in cognitively normal samples have been a focus of recent research. The goal of the current study is to illustrate how Bayes' theorem uses these base rates--along with the same base rates in cognitively impaired samples and prevalence rates of cognitive impairment--to yield probability values that are more useful for making judgments about the absence or presence of cognitive impairment. Correlation matrices, means, and standard deviations were obtained from the Wechsler Memory Scale--4th Edition (WMS-IV) Technical and Interpretive Manual and used in Monte Carlo simulations to estimate the base rates of abnormal test scores in the standardization and special groups (mixed clinical) samples. Bayes' theorem was applied to these estimates to identify probabilities of normal cognition based on the number of abnormal test scores observed. Abnormal scores were common in the standardization sample (65.4% scoring below a scaled score of 7 on at least one subtest) and more common in the mixed clinical sample (85.6% scoring below a scaled score of 7 on at least one subtest). Probabilities varied according to the number of abnormal test scores, base rates of normal cognition, and cutoff scores. The results suggest that interpretation of base rates obtained from cognitively healthy samples must also account for data from cognitively impaired samples. Bayes' theorem can help neuropsychologists answer questions about the probability that an individual examinee is cognitively healthy based on the number of abnormal test scores observed.

Effects on Task Performance and Psychophysiological Measures of Performance During Normobaric Hypoxia Exposure

NASA Technical Reports Server (NTRS)

Stephens, Chad; Kennedy, Kellie; Napoli, Nicholas; Demas, Matthew; Barnes, Laura; Crook, Brenda; Williams, Ralph; Last, Mary Carolyn; Schutte, Paul

2017-01-01

Human-autonomous systems have the potential to mitigate pilot cognitive impairment and improve aviation safety. A research team at NASA Langley conducted an experiment to study the impact of mild normobaric hypoxia induction on aircraft pilot performance and psychophysiological state. A within-subjects design involved non-hypoxic and hypoxic exposures while performing three 10-minute tasks. Results indicated the effect of 15,000 feet simulated altitude did not induce significant performance decrement but did produce increase in perceived workload. Analyses of psychophysiological responses evince the potential of biomarkers for hypoxia onset. This study represents on-going work at NASA intending to add to the current knowledge of psychophysiologically-based input to automation to increase aviation safety. Analyses involving coupling across physiological systems and wavelet transforms of cortical activity revealed patterns that can discern between the simulated altitude conditions. Specifically, multivariate entropy of ECG/Respiration components were found to be significant predictors (p< 0.02) of hypoxia. Furthermore, in EEG, there was a significant decrease in mid-level beta (15.19-18.37Hz) during the hypoxic condition in thirteen of sixteen sites across the scalp. Task performance was not appreciably impacted by the effect of 15,000 feet simulated altitude. Analyses of psychophysiological responses evince the potential of biomarkers for mild hypoxia onset.The potential for identifying shifts in underlying cortical and physiological systems could serve as a means to identify the onset of deteriorated cognitive state. Enabling such assessment in future flightdecks could permit increasingly autonomous systems-supported operations. Augmenting human operator through assessment of cognitive impairment has the potential to further improve operator performance and mitigate human error in safety critical contexts. This study represents ongoing work at NASA intending to add to the current knowledge of psychophysiologically-based input to automation to increase aviation safety.

The relationship between driving simulation performance and obstructive sleep apnoea risk, daytime sleepiness, obesity and road traffic accident history of commercial drivers in Turkey.

PubMed

Demirdöğen Çetinoğlu, Ezgi; Görek Dilektaşlı, Aslı; Demir, Nefise Ateş; Özkaya, Güven; Acet, Nilüfer Aylin; Durmuş, Eda; Ursavaş, Ahmet; Karadağ, Mehmet; Ege, Ercüment

2015-09-01

Driving performance is known to be very sensitive to cognitive-psychomotor impairment. The aim of the study was to determine the relationship between obesity, risk of obstructive sleep apnoea (OSA), daytime sleepiness, history of road traffic accident (RTA) and performance on a driving simulator, among commercial drivers. We examined commercial vehicle drivers admitted to Psycho-Technical Assessment System (PTAS), which is a computer-aided system that includes a driving simulator test and tests assessing psychomotor-cognitive skills required for driving. Risk of OSA and daytime sleepiness were assessed by the Berlin Questionnaire and the Epworth Sleepiness Scale (ESS), respectively. A total of 282 commercial vehicle drivers were consecutively enrolled. The age range was 29-76 years. Thirty drivers were at high risk of OSA. Median ESS of the group was 2 (0-20). Forty-seven percent of the subjects at high risk of OSA failed in early reaction time test, while 28% of the drivers with low risk of OSA failed (p = 0.03). The obese drivers failed the peripheral vision test when compared with non-obese drivers (p = 0.02). ESS was higher for drivers with a history of RTA when compared to those without RTA (p = 0.02). Cognitive-psychomotor functions can be impaired in obese and high risk of OSA patients. In our opinion, requiring obese and/or high risk of OSA drivers to take PTAS tests that assess driving skills and psychomotor-cognitive functions crucial to those skills would significantly improve road traffic safety, which is of considerable importance to public health.

Bacterial Adherence and Dwelling Probability: Two Drivers of Early Alveolar Infection by Streptococcus pneumoniae Identified in Multi-Level Mathematical Modeling

PubMed Central

Santos, Guido; Lai, Xin; Eberhardt, Martin; Vera, Julio

2018-01-01

Pneumococcal infection is the most frequent cause of pneumonia, and one of the most prevalent diseases worldwide. The population groups at high risk of death from bacterial pneumonia are infants, elderly and immunosuppressed people. These groups are more vulnerable because they have immature or impaired immune systems, the efficacy of their response to vaccines is lower, and antibiotic treatment often does not take place until the inflammatory response triggered is already overwhelming. The immune response to bacterial lung infections involves dynamic interactions between several types of cells whose activation is driven by intracellular molecular networks. A feasible approach to the integration of knowledge and data linking tissue, cellular and intracellular events and the construction of hypotheses in this area is the use of mathematical modeling. For this paper, we used a multi-level computational model to analyse the role of cellular and molecular interactions during the first 10 h after alveolar invasion of Streptococcus pneumoniae bacteria. By “multi-level” we mean that we simulated the interplay between different temporal and spatial scales in a single computational model. In this instance, we included the intracellular scale of processes driving lung epithelial cell activation together with the scale of cell-to-cell interactions at the alveolar tissue. In our analysis, we combined systematic model simulations with logistic regression analysis and decision trees to find genotypic-phenotypic signatures that explain differences in bacteria strain infectivity. According to our simulations, pneumococci benefit from a high dwelling probability and a high proliferation rate during the first stages of infection. In addition to this, the model predicts that during the very early phases of infection the bacterial capsule could be an impediment to the establishment of the alveolar infection because it impairs bacterial colonization. PMID:29868515

Alcohol Dose Effects on Brain Circuits During Simulated Driving: An fMRI Study

PubMed Central

Meda, Shashwath A.; Calhoun, Vince D.; Astur, Robert S.; Turner, Beth M.; Ruopp, Kathryn; Pearlson, Godfrey D.

2009-01-01

Driving while intoxicated remains a major public health hazard. Driving is a complex task involving simultaneous recruitment of multiple cognitive functions. The investigators studied the neural substrates of driving and their response to different blood alcohol concentrations (BACs), using functional magnetic resonance imaging (fMRI) and a virtual reality driving simulator. We used independent component analysis (ICA) to isolate spatially independent and temporally correlated driving-related brain circuits in 40 healthy, adult moderate social drinkers. Each subject received three individualized, separate single-blind doses of beverage alcohol to produce BACs of 0.05% (moderate), 0.10% (high), or 0% (placebo). 3 T fMRI scanning and continuous behavioral measurement occurred during simulated driving. Brain function was assessed and compared using both ICA and a conventional general linear model (GLM) analysis. ICA results replicated and significantly extended our previous 1.5T study (Calhoun et al. [2004a]: Neuropsychopharmacology 29:2097–2017). GLM analysis revealed significant dose-related functional differences, complementing ICA data. Driving behaviors including opposite white line crossings and mean speed independently demonstrated significant dose-dependent changes. Behavior-based factors also predicted a frontal-basal-temporal circuit to be functionally impaired with alcohol dosage across baseline scaled, good versus poorly performing drivers. We report neural correlates of driving behavior and found dose-related spatio-temporal disruptions in critical driving-associated regions including the superior, middle and orbito frontal gyri, anterior cingulate, primary/supplementary motor areas, basal ganglia, and cerebellum. Overall, results suggest that alcohol (especially at high doses) causes significant impairment of both driving behavior and brain functionality related to motor planning and control, goal directedness, error monitoring, and memory. PMID:18571794

Bacterial Adherence and Dwelling Probability: Two Drivers of Early Alveolar Infection by Streptococcus pneumoniae Identified in Multi-Level Mathematical Modeling.

PubMed

Santos, Guido; Lai, Xin; Eberhardt, Martin; Vera, Julio

2018-01-01

Pneumococcal infection is the most frequent cause of pneumonia, and one of the most prevalent diseases worldwide. The population groups at high risk of death from bacterial pneumonia are infants, elderly and immunosuppressed people. These groups are more vulnerable because they have immature or impaired immune systems, the efficacy of their response to vaccines is lower, and antibiotic treatment often does not take place until the inflammatory response triggered is already overwhelming. The immune response to bacterial lung infections involves dynamic interactions between several types of cells whose activation is driven by intracellular molecular networks. A feasible approach to the integration of knowledge and data linking tissue, cellular and intracellular events and the construction of hypotheses in this area is the use of mathematical modeling. For this paper, we used a multi-level computational model to analyse the role of cellular and molecular interactions during the first 10 h after alveolar invasion of Streptococcus pneumoniae bacteria. By "multi-level" we mean that we simulated the interplay between different temporal and spatial scales in a single computational model. In this instance, we included the intracellular scale of processes driving lung epithelial cell activation together with the scale of cell-to-cell interactions at the alveolar tissue. In our analysis, we combined systematic model simulations with logistic regression analysis and decision trees to find genotypic-phenotypic signatures that explain differences in bacteria strain infectivity. According to our simulations, pneumococci benefit from a high dwelling probability and a high proliferation rate during the first stages of infection. In addition to this, the model predicts that during the very early phases of infection the bacterial capsule could be an impediment to the establishment of the alveolar infection because it impairs bacterial colonization.

The relationship between cell phone use and management of driver fatigue: It's complicated.

PubMed

Saxby, Dyani Juanita; Matthews, Gerald; Neubauer, Catherine

2017-06-01

Voice communication may enhance performance during monotonous, potentially fatiguing driving conditions (Atchley & Chan, 2011); however, it is unclear whether safety benefits of conversation are outweighed by costs. The present study tested whether personalized conversations intended to simulate hands-free cell phone conversation may counter objective and subjective fatigue effects elicited by vehicle automation. A passive fatigue state (Desmond & Hancock, 2001), characterized by disengagement from the task, was induced using full vehicle automation prior to drivers resuming full control over the driving simulator. A conversation was initiated shortly after reversion to manual control. During the conversation an emergency event occurred. The fatigue manipulation produced greater task disengagement and slower response to the emergency event, relative to a control condition. Conversation did not mitigate passive fatigue effects; rather, it added worry about matters unrelated to the driving task. Conversation moderately improved vehicle control, as measured by SDLP, but it failed to counter fatigue-induced slowing of braking in response to an emergency event. Finally, conversation appeared to have a hidden danger in that it reduced drivers' insights into performance impairments when in a state of passive fatigue. Automation induced passive fatigue, indicated by loss of task engagement; yet, simulated cell phone conversation did not counter the subjective automation-induced fatigue. Conversation also failed to counter objective loss of performance (slower braking speed) resulting from automation. Cell phone conversation in passive fatigue states may impair drivers' awareness of their performance deficits. Practical applications: Results suggest that conversation, even using a hands-free device, may not be a safe way to reduce fatigue and increase alertness during transitions from automated to manual vehicle control. Copyright © 2017 Elsevier Ltd and National Safety Council. All rights reserved.

Bioinstrumentation for evaluation of workload in payload specialists: results of ASSESS II

NASA Astrophysics Data System (ADS)

Wegmann, Hans M.; Herrmann, Reinhold; Winget, Charles M.

1980-11-01

ASSESS II‡Acronym for Airborne Science/Spacelab Experiments System Simulation. was a cooperative NASA-ESA project which consisted of a detailed simulation of Spacelab operations using the NASA Ames Research Center CV-990 aircraft laboratory. The Medical Experiment reported on in this paper was part of the complex payload consisting of 11 different experiments. Its general purpose was to develop a technology, possibly flown on board of Spacelab, and enabling the assessment of workload through evaluating changes of circadian rhythmicity, sleep disturbances and episodical or cumulative stress. As parameters the following variables were measured: Rectal temperature, ECG, sleep-EEG and -EOG, the urinary excretion of hormones and electrolytes. The results revealed evidence that a Spacelab environment, as simulated in ASSESS II, will lead to internal dissociation of circadian rhythms, to sleep disturbances and to highly stressful working conditions. Altogether these effects will impose considerable workload upon Payload Specialists. It is suggested that an intensive pre-mission system simulation will reduce these impairments to a reasonable degree. The bioinstrumentation applied in this experiment proved to be a practical and reliable tool in assessing the objectives of the study.

The (In)Effectiveness of Simulated Blur for Depth Perception in Naturalistic Images.

PubMed

Maiello, Guido; Chessa, Manuela; Solari, Fabio; Bex, Peter J

2015-01-01

We examine depth perception in images of real scenes with naturalistic variation in pictorial depth cues, simulated dioptric blur and binocular disparity. Light field photographs of natural scenes were taken with a Lytro plenoptic camera that simultaneously captures images at up to 12 focal planes. When accommodation at any given plane was simulated, the corresponding defocus blur at other depth planes was extracted from the stack of focal plane images. Depth information from pictorial cues, relative blur and stereoscopic disparity was separately introduced into the images. In 2AFC tasks, observers were required to indicate which of two patches extracted from these images was farther. Depth discrimination sensitivity was highest when geometric and stereoscopic disparity cues were both present. Blur cues impaired sensitivity by reducing the contrast of geometric information at high spatial frequencies. While simulated generic blur may not assist depth perception, it remains possible that dioptric blur from the optics of an observer's own eyes may be used to recover depth information on an individual basis. The implications of our findings for virtual reality rendering technology are discussed.

The (In)Effectiveness of Simulated Blur for Depth Perception in Naturalistic Images

PubMed Central

Maiello, Guido; Chessa, Manuela; Solari, Fabio; Bex, Peter J.

2015-01-01

We examine depth perception in images of real scenes with naturalistic variation in pictorial depth cues, simulated dioptric blur and binocular disparity. Light field photographs of natural scenes were taken with a Lytro plenoptic camera that simultaneously captures images at up to 12 focal planes. When accommodation at any given plane was simulated, the corresponding defocus blur at other depth planes was extracted from the stack of focal plane images. Depth information from pictorial cues, relative blur and stereoscopic disparity was separately introduced into the images. In 2AFC tasks, observers were required to indicate which of two patches extracted from these images was farther. Depth discrimination sensitivity was highest when geometric and stereoscopic disparity cues were both present. Blur cues impaired sensitivity by reducing the contrast of geometric information at high spatial frequencies. While simulated generic blur may not assist depth perception, it remains possible that dioptric blur from the optics of an observer’s own eyes may be used to recover depth information on an individual basis. The implications of our findings for virtual reality rendering technology are discussed. PMID:26447793

SATCOM simulator speeds MSS deployment and lowers costs

NASA Technical Reports Server (NTRS)

Carey, Tim; Hassun, Roland; Koberstein, Dave

1993-01-01

Mobile satellite systems (MSS) are being proposed and licensed at an accelerating rate. How can the design, manufacture, and performance of these systems be optimized at costs that allow a reasonable return on investment? The answer is the use of system simulation techniques beginning early in the system design and continuing through integration, pre- and post-launch monitoring, and in-orbit monitoring. This paper focuses on using commercially available, validated simulation instruments to deliver accurate, repeatable, and cost effective measurements throughout the life of a typical mobile satellite system. A satellite communications test set is discussed that provides complete parametric test capability with a significant improvement in measurement speed for manufacturing, integration, and pre-launch and in-orbit testing. The test set can simulate actual up and down link traffic conditions to evaluate the effects of system impairments, propagation and multipath on bit error rate (BER), channel capacity and transponder and system load balancing. Using a standard set of commercial instruments to deliver accurate, verifiable measurements anywhere in the world speeds deployment, generates measurement confidence, and lowers total system cost.

Falls Risk and Simulated Driving Performance in Older Adults

PubMed Central

Gaspar, John G.; Neider, Mark B.; Kramer, Arthur F.

2013-01-01

Declines in executive function and dual-task performance have been related to falls in older adults, and recent research suggests that older adults at risk for falls also show impairments on real-world tasks, such as crossing a street. The present study examined whether falls risk was associated with driving performance in a high-fidelity simulator. Participants were classified as high or low falls risk using the Physiological Profile Assessment and completed a number of challenging simulated driving assessments in which they responded quickly to unexpected events. High falls risk drivers had slower response times (~2.1 seconds) to unexpected events compared to low falls risk drivers (~1.7 seconds). Furthermore, when asked to perform a concurrent cognitive task while driving, high falls risk drivers showed greater costs to secondary task performance than did low falls risk drivers, and low falls risk older adults also outperformed high falls risk older adults on a computer-based measure of dual-task performance. Our results suggest that attentional differences between high and low falls risk older adults extend to simulated driving performance. PMID:23509627

First-order exchange coefficient coupling for simulating surface water-groundwater interactions: Parameter sensitivity and consistency with a physics-based approach

USGS Publications Warehouse

Ebel, B.A.; Mirus, B.B.; Heppner, C.S.; VanderKwaak, J.E.; Loague, K.

2009-01-01

Distributed hydrologic models capable of simulating fully-coupled surface water and groundwater flow are increasingly used to examine problems in the hydrologic sciences. Several techniques are currently available to couple the surface and subsurface; the two most frequently employed approaches are first-order exchange coefficients (a.k.a., the surface conductance method) and enforced continuity of pressure and flux at the surface-subsurface boundary condition. The effort reported here examines the parameter sensitivity of simulated hydrologic response for the first-order exchange coefficients at a well-characterized field site using the fully coupled Integrated Hydrology Model (InHM). This investigation demonstrates that the first-order exchange coefficients can be selected such that the simulated hydrologic response is insensitive to the parameter choice, while simulation time is considerably reduced. Alternatively, the ability to choose a first-order exchange coefficient that intentionally decouples the surface and subsurface facilitates concept-development simulations to examine real-world situations where the surface-subsurface exchange is impaired. While the parameters comprising the first-order exchange coefficient cannot be directly estimated or measured, the insensitivity of the simulated flow system to these parameters (when chosen appropriately) combined with the ability to mimic actual physical processes suggests that the first-order exchange coefficient approach can be consistent with a physics-based framework. Copyright ?? 2009 John Wiley & Sons, Ltd.

Testing a structural model for viral DNA packaging motor function by optical tweezers measurements, site directed mutagenesis, and molecular dynamics calculations

NASA Astrophysics Data System (ADS)

Keller, Nicholas A.; Migliori, Amy D.; Arya, Gaurav; Rao, Venigalla B.; Smith, Douglas E.

2013-09-01

Many double-stranded DNA viruses employ a molecular motor to package DNA into preformed capsid shells. Based on structures of phage T4 motor proteins determined by X-ray crystallography and cryo-electron microscopy, Rao, Rossmann and coworkers recently proposed a structural model for motor function. They proposed that DNA is ratcheted by a large conformational change driven by electrostatic interactions between charged residues at an interface between two globular domains of the motor protein. We have conducted experiments to test this model by studying the effect on packaging under applied load of site-directed changes altering these residues. We observe significant impairment of packaging activity including reductions in packaging rate, percent time packaging, and time active under high load. We show that these measured impairments correlate well with alterations in free energies associated with the conformational change predicted by molecular dynamics simulations.

Dynamic Bayesian network modeling for longitudinal brain morphometry

PubMed Central

Chen, Rong; Resnick, Susan M; Davatzikos, Christos; Herskovits, Edward H

2011-01-01

Identifying interactions among brain regions from structural magnetic-resonance images presents one of the major challenges in computational neuroanatomy. We propose a Bayesian data-mining approach to the detection of longitudinal morphological changes in the human brain. Our method uses a dynamic Bayesian network to represent evolving inter-regional dependencies. The major advantage of dynamic Bayesian network modeling is that it can represent complicated interactions among temporal processes. We validated our approach by analyzing a simulated atrophy study, and found that this approach requires only a small number of samples to detect the ground-truth temporal model. We further applied dynamic Bayesian network modeling to a longitudinal study of normal aging and mild cognitive impairment — the Baltimore Longitudinal Study of Aging. We found that interactions among regional volume-change rates for the mild cognitive impairment group are different from those for the normal-aging group. PMID:21963916

A Physiological Signal Transmission Model to be Used for Specific Diagnosis of Cochlear Impairments

NASA Astrophysics Data System (ADS)

Saremi, Amin; Stenfelt, Stefan

2011-11-01

Many of the sophisticated characteristics of human auditory system are attributed to cochlea. Also, most of patients with a hearing loss suffer from impairments that originate from cochlea (sensorineural). Despite this, today's clinical diagnosis methods do not probe the specific origins of such cochlear lesions. The aim of this research is to introduce a physiological signal transmission model to be clinically used as a tool for diagnosis of cochlear losses. This model enables simulation of different bio-mechano-electrical processes which occur in the auditory organ of Corti inside the cochlea. What makes this model different from many available computational models is its loyalty to physiology since the ultimate goal is to model each single physiological phenomenon. This includes passive BM vibration, outer hair cells' performances such as nonlinear mechanoelectrical transduction (MET), active amplifications by somatic motor, as well as vibration to neural conversion at the inner hair cells.

Ocular disease and driving.

PubMed

Wood, Joanne M; Black, Alex A

2016-09-01

As the driving population ages, the number of drivers with visual impairment resulting from ocular disease will increase given the age-related prevalence of ocular disease. The increase in visual impairment in the driving population has a number of implications for driving outcomes. This review summarises current research regarding the impact of common ocular diseases on driving ability and safety, with particular focus on cataract, glaucoma, age-related macular degeneration, hemianopia and diabetic retinopathy. The evidence considered includes self-reported driving outcomes, driving performance (on-road and simulator-based) and various motor vehicle crash indices. Collectively, this review demonstrates that driving ability and safety are negatively affected by ocular disease; however, further research is needed in this area. Older drivers with ocular disease need to be aware of the negative consequences of their ocular condition and in the case where treatment options are available, encouraged to seek these earlier for optimum driving safety and quality of life benefits. © 2016 Optometry Australia.

Serious games for screening pre-dementia conditions: from virtuality to reality? A pilot project.

PubMed

Zucchella, Chiara; Sinforiani, Elena; Tassorelli, Cristina; Cavallini, Elena; Tost-Pardell, Daniela; Grau, Sergi; Pazzi, Stefania; Puricelli, Stefano; Bernini, Sara; Bottiroli, Sara; Vecchi, Tomaso; Sandrini, Giorgio; Nappi, Giuseppe

2014-01-01

Conventional cognitive assessment is based on a pencil-and-paper neuropsychological evaluation, which is time consuming, expensive and requires the involvement of several professionals. Information and communication technology could be exploited to allow the development of tools that are easy to use, reduce the amount of data processing, and provide controllable test conditions. Serious games (SGs) have the potential to be new and effective tools in the management and treatment of cognitive impairments Serious games for screening pre-dementia conditions: from virtuality to reality? A pilot project in the elderly. Moreover, by adopting SGs in 3D virtual reality settings, cognitive functions might be evaluated using tasks that simulate daily activities, increasing the "ecological validity" of the assessment. In this commentary we report our experience in the creation of the Smart Aging platform, a 3D SGand virtual environment-based platform for the early identification and characterization of mild cognitive impairment.

Driving and Neurodegenerative Diseases

PubMed Central

Uc, Ergun Y.; Rizzo, Matthew

2011-01-01

The proportion of elderly in the general population is rising, resulting in greater numbers of drivers with neurodegenerative disorders such as Alzheimer’s disease (AD) and Parkinson’s disease (PD). These neurodegenerative disorders impair cognition, visual perception, and motor function, leading to reduced driver fitness and greater crash risk. Yet medical diagnosis or age alone is not reliable enough to predict driver safety or crashes, or revoke the driving privileges of these drivers. Driving research utilizes tools such as questionnaires about driving habits and history, driving simulators, standardized road tests utilizing instrumented vehicles, and state driving records. Research challenges include outlining the evolution of driving safety, understanding the mechanisms of driving impairment, and developing a reliable and efficient standardized test battery for prediction of driver safety in neurodegenerative disorders. This information will enable healthcare providers to advise their patients with neurodegenerative disorders with more certainty, affect policy, and help to develop rehabilitative measures for driving. PMID:18713573

Drivers who self-estimate lower blood alcohol concentrations are riskier drivers after drinking

PubMed Central

Laude, Jennifer R.; Fillmore, Mark T.

2016-01-01

Rationale Alcohol increases the tendency for risky driving in some individuals, but not others. Little is known about the factors underlying this individual difference. Studies find that those who underestimate their blood alcohol concentration (BAC) following a dose of alcohol tend to be more impulsive and report greater willingness to drive after drinking than those who estimate their BACs to be greater than their actual BAC. BAC underestimation could contribute to risky driving behavior following alcohol as such drivers might perceive little impairment in their driving ability and thus no need for caution. Objectives This study was designed to test the relationship between drivers’ BAC estimations following a dose of alcohol or a placebo and the degree of risky driving they displayed during a simulated driving test. Methods Forty adult drivers performed a simulated driving test and estimated their blood alcohol concentration after receiving a dose of alcohol (0.65 g/kg for men; 0.56 g/kg for women) or a placebo. . Results Alcohol increased risk taking and impaired driving skill. Those who estimated their BAC to be lower were the riskiest drivers following both alcohol and placebo. Conclusions The tendency to estimate lower BACs could support a series of high-risk decisions, regardless of one’s actual BAC. This could include the decision to drive after drinking. PMID:26861796

A hybrid stochastic model of folate-mediated one-carbon metabolism: Effect of the common C677T MTHFR variant on de novo thymidylate biosynthesis.

PubMed

Misselbeck, Karla; Marchetti, Luca; Field, Martha S; Scotti, Marco; Priami, Corrado; Stover, Patrick J

2017-04-11

Folate-mediated one-carbon metabolism (FOCM) is an interconnected network of metabolic pathways, including those required for the de novo synthesis of dTMP and purine nucleotides and for remethylation of homocysteine to methionine. Mouse models of folate-responsive neural tube defects (NTDs) indicate that impaired de novo thymidylate (dTMP) synthesis through changes in SHMT expression is causative in folate-responsive NTDs. We have created a hybrid computational model comprised of ordinary differential equations and stochastic simulation. We investigated whether the de novo dTMP synthesis pathway was sensitive to perturbations in FOCM that are known to be associated with human NTDs. This computational model shows that de novo dTMP synthesis is highly sensitive to the common MTHFR C677T polymorphism and that the effect of the polymorphism on FOCM is greater in folate deficiency. Computational simulations indicate that the MTHFR C677T polymorphism and folate deficiency interact to increase the stochastic behavior of the FOCM network, with the greatest instability observed for reactions catalyzed by serine hydroxymethyltransferase (SHMT). Furthermore, we show that de novo dTMP synthesis does not occur in the cytosol at rates sufficient for DNA replication, supporting empirical data indicating that impaired nuclear de novo dTMP synthesis results in uracil misincorporation into DNA.

New scoring methodology improves the sensitivity of the Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog) in clinical trials.

PubMed

Verma, Nishant; Beretvas, S Natasha; Pascual, Belen; Masdeu, Joseph C; Markey, Mia K

2015-11-12

As currently used, the Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog) has low sensitivity for measuring Alzheimer's disease progression in clinical trials. A major reason behind the low sensitivity is its sub-optimal scoring methodology, which can be improved to obtain better sensitivity. Using item response theory, we developed a new scoring methodology (ADAS-CogIRT) for the ADAS-Cog, which addresses several major limitations of the current scoring methodology. The sensitivity of the ADAS-CogIRT methodology was evaluated using clinical trial simulations as well as a negative clinical trial, which had shown an evidence of a treatment effect. The ADAS-Cog was found to measure impairment in three cognitive domains of memory, language, and praxis. The ADAS-CogIRT methodology required significantly fewer patients and shorter trial durations as compared to the current scoring methodology when both were evaluated in simulated clinical trials. When validated on data from a real clinical trial, the ADAS-CogIRT methodology had higher sensitivity than the current scoring methodology in detecting the treatment effect. The proposed scoring methodology significantly improves the sensitivity of the ADAS-Cog in measuring progression of cognitive impairment in clinical trials focused in the mild-to-moderate Alzheimer's disease stage. This provides a boost to the efficiency of clinical trials requiring fewer patients and shorter durations for investigating disease-modifying treatments.

Survival and death of the haloarchaeon Natronorubrum strain HG-1 in a simulated martian environment

NASA Astrophysics Data System (ADS)

Peeters, Z.; Vos, D.; ten Kate, I. L.; Selch, F.; van Sluis, C. A.; Sorokin, D. Yu.; Muijzer, G.; Stan-Lotter, H.; van Loosdrecht, M. C. M.; Ehrenfreund, P.

2010-11-01

Halophilic archaea are of interest to astrobiology due to their survival capabilities in desiccated and high salt environments. The detection of remnants of salty pools on Mars stimulated investigations into the response of haloarchaea to martian conditions. Natronorubrum sp. strain HG-1 is an extremely halophilic archaeon with unusual metabolic pathways, growing on acetate and stimulated by tetrathionate. We exposed Natronorubrum strain HG-1 to ultraviolet (UV) radiation, similar to levels currently prevalent on Mars. In addition, the effects of low temperature (4, -20, and -80 °C), desiccation, and exposure to a Mars soil analogue from the Atacama desert on the viability of Natronorubrum strain HG-1 cultures were investigated. The results show that Natronorubrum strain HG-1 cannot survive for more than several hours when exposed to UV radiation equivalent to that at the martian equator. Even when protected from UV radiation, viability is impaired by a combination of desiccation and low temperature. Desiccating Natronorubrum strain HG-1 cells when mixed with a Mars soil analogue impaired growth of the culture to below the detection limit. Overall, we conclude that Natronorubrum strain HG-1 cannot survive the environment currently present on Mars. Since other halophilic microorganisms were reported to survive simulated martian conditions, our results imply that survival capabilities are not necessarily shared between phylogenetically related species.

Impaired Air Conditioning within the Nasal Cavity in Flat-Faced Homo

PubMed Central

Nishimura, Takeshi; Mori, Futoshi; Hanida, Sho; Kumahata, Kiyoshi; Ishikawa, Shigeru; Samarat, Kaouthar; Miyabe-Nishiwaki, Takako; Hayashi, Misato; Tomonaga, Masaki; Suzuki, Juri; Matsuzawa, Tetsuro; Matsuzawa, Teruo

2016-01-01

We are flat-faced hominins with an external nose that protrudes from the face. This feature was derived in the genus Homo, along with facial flattening and reorientation to form a high nasal cavity. The nasal passage conditions the inhaled air in terms of temperature and humidity to match the conditions required in the lung, and its anatomical variation is believed to be evolutionarily sensitive to the ambient atmospheric conditions of a given habitat. In this study, we used computational fluid dynamics (CFD) with three-dimensional topology models of the nasal passage under the same simulation conditions, to investigate air-conditioning performance in humans, chimpanzees, and macaques. The CFD simulation showed a horizontal straight flow of inhaled air in chimpanzees and macaques, contrasting with the upward and curved flow in humans. The inhaled air is conditioned poorly in humans compared with nonhuman primates. Virtual modifications to the human external nose topology, in which the nasal vestibule and valve are modified to resemble those of chimpanzees, change the airflow to be horizontal, but have little influence on the air-conditioning performance in humans. These findings suggest that morphological variation of the nasal passage topology was only weakly sensitive to the ambient atmosphere conditions; rather, the high nasal cavity in humans was formed simply by evolutionary facial reorganization in the divergence of Homo from the other hominin lineages, impairing the air-conditioning performance. Even though the inhaled air is not adjusted well within the nasal cavity in humans, it can be fully conditioned subsequently in the pharyngeal cavity, which is lengthened in the flat-faced Homo. Thus, the air-conditioning faculty in the nasal passages was probably impaired in early Homo members, although they have survived successfully under the fluctuating climate of the Plio-Pleistocene, and then they moved “Out of Africa” to explore the more severe climates of Eurasia. PMID:27010321

Impaired Air Conditioning within the Nasal Cavity in Flat-Faced Homo.

PubMed

Nishimura, Takeshi; Mori, Futoshi; Hanida, Sho; Kumahata, Kiyoshi; Ishikawa, Shigeru; Samarat, Kaouthar; Miyabe-Nishiwaki, Takako; Hayashi, Misato; Tomonaga, Masaki; Suzuki, Juri; Matsuzawa, Tetsuro; Matsuzawa, Teruo

2016-03-01

We are flat-faced hominins with an external nose that protrudes from the face. This feature was derived in the genus Homo, along with facial flattening and reorientation to form a high nasal cavity. The nasal passage conditions the inhaled air in terms of temperature and humidity to match the conditions required in the lung, and its anatomical variation is believed to be evolutionarily sensitive to the ambient atmospheric conditions of a given habitat. In this study, we used computational fluid dynamics (CFD) with three-dimensional topology models of the nasal passage under the same simulation conditions, to investigate air-conditioning performance in humans, chimpanzees, and macaques. The CFD simulation showed a horizontal straight flow of inhaled air in chimpanzees and macaques, contrasting with the upward and curved flow in humans. The inhaled air is conditioned poorly in humans compared with nonhuman primates. Virtual modifications to the human external nose topology, in which the nasal vestibule and valve are modified to resemble those of chimpanzees, change the airflow to be horizontal, but have little influence on the air-conditioning performance in humans. These findings suggest that morphological variation of the nasal passage topology was only weakly sensitive to the ambient atmosphere conditions; rather, the high nasal cavity in humans was formed simply by evolutionary facial reorganization in the divergence of Homo from the other hominin lineages, impairing the air-conditioning performance. Even though the inhaled air is not adjusted well within the nasal cavity in humans, it can be fully conditioned subsequently in the pharyngeal cavity, which is lengthened in the flat-faced Homo. Thus, the air-conditioning faculty in the nasal passages was probably impaired in early Homo members, although they have survived successfully under the fluctuating climate of the Plio-Pleistocene, and then they moved "Out of Africa" to explore the more severe climates of Eurasia.

Cannabis effects on driving lateral control with and without alcohol.

PubMed

Hartman, Rebecca L; Brown, Timothy L; Milavetz, Gary; Spurgin, Andrew; Pierce, Russell S; Gorelick, David A; Gaffney, Gary; Huestis, Marilyn A

2015-09-01

Effects of cannabis, the most commonly encountered non-alcohol drug in driving under the influence cases, are heavily debated. We aim to determine how blood Δ(9)-tetrahydrocannabinol (THC) concentrations relate to driving impairment, with and without alcohol. Current occasional (≥1×/last 3 months, ≤3days/week) cannabis smokers drank placebo or low-dose alcohol, and inhaled 500mg placebo, low (2.9%)-THC, or high (6.7%)-THC vaporized cannabis over 10min ad libitum in separate sessions (within-subject design, 6 conditions). Participants drove (National Advanced Driving Simulator, University of Iowa) simulated drives (∼0.8h duration). Blood, oral fluid (OF), and breath alcohol samples were collected before (0.17h, 0.42h) and after (1.4h, 2.3h) driving that occurred 0.5-1.3h after inhalation. We evaluated standard deviations of lateral position (lane weave, SDLP) and steering angle, lane departures/min, and maximum lateral acceleration. In N=18 completers (13 men, ages 21-37years), cannabis and alcohol increased SDLP. Blood THC concentrations of 8.2 and 13.1μg/L during driving increased SDLP similar to 0.05 and 0.08g/210L breath alcohol concentrations, the most common legal alcohol limits. Cannabis-alcohol SDLP effects were additive rather than synergistic, with 5μg/L THC+0.05g/210L alcohol showing similar SDLP to 0.08g/210L alcohol alone. Only alcohol increased lateral acceleration and the less-sensitive lane departures/min parameters. OF effectively documented cannabis exposure, although with greater THC concentration variability than paired blood samples. SDLP was a sensitive cannabis-related lateral control impairment measure. During drive blood THC ≥8.2μg/L increased SDLP similar to notably-impairing alcohol concentrations. Despite OF's screening value, OF variability poses challenges in concentration-based effects interpretation. Published by Elsevier Ireland Ltd.

Performance-based robotic assistance during rhythmic arm exercises.

PubMed

Leconte, Patricia; Ronsse, Renaud

2016-09-13

Rhythmic and discrete upper-limb movements are two fundamental motor primitives controlled by different neural pathways, at least partially. After stroke, both primitives can be impaired. Both conventional and robot-assisted therapies mainly train discrete functional movements like reaching and grasping. However, if the movements form two distinct neural and functional primitives, both should be trained to recover the complete motor repertoire. Recent studies show that rhythmic movements tend to be less impaired than discrete ones, so combining both movement types in therapy could support the execution of movements with a higher degree of impairment by movements that are performed more stably. A new performance-based assistance method was developed to train rhythmic movements with a rehabilitation robot. The algorithm uses the assist-as-needed paradigm by independently assessing and assisting movement features of smoothness, velocity, and amplitude. The method relies on different building blocks: (i) an adaptive oscillator captures the main movement harmonic in state variables, (ii) custom metrics measure the movement performance regarding the three features, and (iii) adaptive forces assist the patient. The patient is encouraged to improve performance regarding these three features with assistance forces computed in parallel to each other. The method was tested with simulated jerky signals and a pilot experiment with two stroke patients, who were instructed to make circular movements with an end-effector robot with assistance during half of the trials. Simulation data reveal sensitivity of the metrics for assessing the features while limiting interference between them. The assistance's effectiveness with stroke patients is established since it (i) adapts to the patient's real-time performance, (ii) improves patient motor performance, and (iii) does not lead the patient to slack. The smoothness assistance was by far the most used by both patients, while it provided no active mechanical work to the patient on average. Our performance-based assistance method for training rhythmic movements is a viable candidate to complement robot-assisted upper-limb therapies for training a larger motor repertoire.

Modeled effects of soil acidification on long-term ecological and economic outcomes for managed forests in the Adirondack region (USA).

PubMed

Caputo, Jesse; Beier, Colin M; Sullivan, Timothy J; Lawrence, Gregory B

2016-09-15

Sugar maple (Acer saccharum) is among the most ecologically and economically important tree species in North America, and its growth and regeneration is often the focus of silvicultural practices in northern hardwood forests. A key stressor for sugar maple (SM) is acid rain, which depletes base cations from poorly-buffered forest soils and has been associated with much lower SM vigor, growth, and recruitment. However, the potential interactions between forest management and soil acidification - and their implications for the sustainability of SM and its economic and cultural benefits - have not been investigated. In this study, we simulated the development of 50 extant SM stands in the western Adirondack region of NY (USA) for 100years under different soil chemical conditions and silvicultural prescriptions. We found that interactions between management prescription and soil base saturation will strongly shape the ability to maintain SM in managed forests. Below 12% base saturation, SM did not regenerate sufficiently after harvest and was replaced mainly by red maple (Acer rubrum) and American beech (Fagus grandifolia). Loss of SM on acid-impaired sites was predicted regardless of whether the shelterwood or diameter-limit prescriptions were used. On soils with sufficient base saturation, models predicted that SM will regenerate after harvest and be sustained for future rotations. We then estimated how these different post-harvest outcomes, mediated by acid impairment of forest soils, would affect the potential monetary value of ecosystem services provided by SM forests. Model simulations indicated that a management strategy focused on syrup production - although not feasible across the vast areas where acid impairment has occurred - may generate the greatest economic return. Although pollution from acid rain is declining, its long-term legacy in forest soils will shape future options for sustainable forestry and ecosystem stewardship in the northern hardwood forests of North America. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Launch Conditions Might Affect the Formation of Blood Vessel in the Quail Chorioallantoic Membrane

NASA Technical Reports Server (NTRS)

Henry, M. K.; Unsworth, B. R.; Sychev, B. R.; Guryeva, T. S.; Dadasheva, O. A.; Piert, S. J.; Lagel, K. E.; Dubrovin, L. C.; Jahns, G. C.; Boda, K.;

Modeled effects of soil acidification on long-term ecological and economic outcomes for managed forests in the Adirondack region (USA)

USGS Publications Warehouse

Caputo, Jesse PhD.; Beier, Colin M.; Sullivan, Timothy J.; Lawrence, Gregory B.

2016-01-01

Sugar maple (Acer saccharum) is among the most ecologically and economically important tree species in North America, and its growth and regeneration is often the focus of silvicultural practices in northern hardwood forests. A key stressor for sugar maple (SM) is acid rain, which depletes base cations from poorly-buffered forest soils and has been associated with much lower SM vigor, growth, and recruitment. However, the potential interactions between forest management and soil acidification – and their implications for the sustainability of SM and its economic and cultural benefits – have not been investigated. In this study, we simulated the development of 50 extant SM stands in the western Adirondack region of NY (USA) for 100 years under different soil chemical conditions and silvicultural prescriptions. We found that interactions between management prescription and soil base saturation will strongly shape the ability to maintain SM in managed forests. Below 12% base saturation, SM did not regenerate sufficiently after harvest and was replaced mainly by red maple (Acer rubrum) and American beech (Fagus grandifolia). Loss of SM on acid-impaired sites was predicted regardless of whether the shelterwood or diameter-limit prescriptions were used. On soils with sufficient base saturation, models predicted that SM will regenerate after harvest and be sustained for future rotations. We then estimated how these different post-harvest outcomes, mediated by acid impairment of forest soils, would affect the potential monetary value of ecosystem services provided by SM forests. Model simulations indicated that a management strategy focused on syrup production – although not feasible across the vast areas where acid impairment has occurred – may generate the greatest economic return. Although pollution from acid rain is declining, its long-term legacy in forest soils will shape future options for sustainable forestry and ecosystem stewardship in the northern hardwood forests of North America.

Positive Affect Is Associated With Reduced Fixation in a Realistic Medical Simulation.

PubMed

Crane, Monique F; Brouwers, Sue; Forrest, Kirsty; Tan, Suyin; Loveday, Thomas; Wiggins, Mark W; Munday, Chris; David, Leila

2017-08-01

This study extends previous research by exploring the association between mood states (i.e., positive and negative affect) and fixation in practicing anesthetists using a realistic medical simulation. The impact of practitioner emotional states on fixation is a neglected area of research. Emerging evidence is demonstrating the role of positive affect in facilitating problem solving and innovation, with demonstrated implications for practitioner fixation. Twelve practicing anesthetists (4 females; M age = 39 years; SD = 6.71) were involved in a medical simulation. Prior to the simulation, practitioners rated the frequency they had experienced various positive and negative emotions in the previous three days. During the simulation, the patient deteriorated rapidly, and anesthetists were observed for their degree of fixation. After the simulation, practitioners indicated the frequency of these same emotions during the simulation. Nonparametric correlations were used to explore the independent relationships between positive and negative affect and the behavioral measures. Only positive affect impacted the likelihood of fixation. Anesthetists who reported more frequent recent positive affect in the three days prior to the simulation and during the simulation tended to be less fixated as judged by independent raters, identified a decline in patient oxygen saturation more quickly, and more rapidly implemented the necessary intervention (surgical cricothyroidotomy). These findings have some real-world implications for positive affect in patient safety. This research has broad implications for professions where fixation may impair practice. This research suggests that professional training should teach practitioners to identify their emotions and understand the role of these emotions in fixation.

The simulated gambling paradigm applied to young adults: an examination of university students' performance.

PubMed

Caroselli, Jerome Silvio; Hiscock, Merrill; Scheibel, Randall S; Ingram, Fred

2006-01-01

Simulated gambling tasks have become popular as sensitive tools for identifying individuals with real-time impairment in decision making. Various clinical samples, especially patients with damage to the ventromedial prefrontal cortex, perform poorly on these tasks. The patients typically persist in choosing risky (disadvantageous) card decks instead of switching to safer (advantageous) decks. In terms of Damasio's (1994) somatic marker hypothesis, the poor performance stems from defective integration of emotional and rational aspects of decision making. Less information is available about performance in healthy populations, particularly young adults. After administering a computerized gambling task to 141 university students, we found that individuals in this population also tend to prefer disadvantageous decks to advantageous decks. The results indicate that performance is governed primarily by the frequency of positive outcomes on a trial-by-trial basis rather than by the accumulation of winnings in the longer term. These findings are discussed in light of the cognitive literature pertaining to the simulated gambling paradigm.

Behavioral and Cardiovascular Responses to Frustration During Simulated Driving Tasks in Young Adults With and Without Attention Disorder Symptoms

PubMed Central

Oliver, Michele L.; Nigg, Joel T.; Cassavaugh, Nicholas D.; Backs, Richard W.

2015-01-01

Objective The present study examined the role of negative emotions on driving performance in relation to ADHD, by comparing young adults scoring high on measures of ADHD (n = 20) with a control group (n = 22). Method The authors used cardiorespiratory physiological measures, simulated driving behavior, and self-report to examine how participants with high and low ADHD symptoms responded to frustration and to determine how frustration affected simulated driving performance. Results Groups did not differ in operational driving skills, but participants with high ADHD symptoms reported more frustration and exhibited more impairment at the tactical level of driving performance than the controls. There was significant suppression of respiratory sinus arrhythmia from resting baseline during tasks, but it did not differ between groups during driving. Conclusion This article proposes that remedial driver training for ADHD populations should focus more on the control of negative emotions rather than on attention or fundamental driving skills. PMID:21490175

Brief Report: Simulations Suggest Heterogeneous Category Learning and Generalization in Children with Autism is a Result of Idiosyncratic Perceptual Transformations.

PubMed

Mercado, Eduardo; Church, Barbara A

2016-08-01

Children with autism spectrum disorder (ASD) sometimes have difficulties learning categories. Past computational work suggests that such deficits may result from atypical representations in cortical maps. Here we use neural networks to show that idiosyncratic transformations of inputs can result in the formation of feature maps that impair category learning for some inputs, but not for other closely related inputs. These simulations suggest that large inter- and intra-individual variations in learning capacities shown by children with ASD across similar categorization tasks may similarly result from idiosyncratic perceptual encoding that is resistant to experience-dependent changes. If so, then both feedback- and exposure-based category learning should lead to heterogeneous, stimulus-dependent deficits in children with ASD.

Impaired alertness and performance driving home from the night shift: a driving simulator study.

PubMed

Akerstedt, Torbjörn; Peters, Björn; Anund, Anna; Kecklund, Göran

2005-03-01

Driving in the early morning is associated with increased accident risk affecting not only professional drivers but also those who commute to work. The present study used a driving simulator to investigate the effects of driving home from a night shift. Ten shift workers participated after a normal night shift and after a normal night sleep. The results showed that driving home from the night shift was associated with an increased number of incidents (two wheels outside the lane marking, from 2.4 to 7.6 times), decreased time to first accident, increased lateral deviation (from 18 to 43 cm), increased eye closure duration (0.102 to 0.143 s), and increased subjective sleepiness. The results indicate severe postnight shift effects on sleepiness and driving performance.

A human fecal contamination index for ranking impaired ...

EPA Pesticide Factsheets

Human fecal pollution of surface water remains a public health concern worldwide. As a result, there is a growing interest in the application of human-associated fecal source identification quantitative real-time PCR (qPCR) technologies for recreational water quality risk management. The transition from a research subject to a management tool requires the integration of standardized water sampling, laboratory, and data analysis procedures. In this study, a standardized HF183/BacR287 qPCR method was combined with a water sampling strategy and Bayesian data algorithm to establish a human fecal contamination index that can be used to rank impaired recreational water sites polluted with human waste. Stability and bias of index predictions were investigated under various parameters including siteswith different pollution levels, sampling period time range (1-15 weeks), and number of qPCR replicates per sample (2-14 replicates). Sensitivity analyses were conducted with simulated data sets (100 iterations) seeded with HF183/BacR287 qPCR laboratory measurements from water samples collected from three Southern California sites (588 qPCR measurements). Findings suggest that site ranking is feasible and that all parameters tested influence stability and bias in human fecal contamination indexscoring. Trends identified by sensitivity analyses will provide managers with the information needed to design and conduct field studies to rank impaired recreational water sites based

Parametric Cognitive Modeling of Information and Computer Technology Usage by People with Aging- and Disability-Derived Functional Impairments

PubMed Central

García-Betances, Rebeca I.; Cabrera-Umpiérrez, María Fernanda; Ottaviano, Manuel; Pastorino, Matteo; Arredondo, María T.

2016-01-01

Despite the speedy evolution of Information and Computer Technology (ICT), and the growing recognition of the importance of the concept of universal design in all domains of daily living, mainstream ICT-based product designers and developers still work without any truly structured tools, guidance or support to effectively adapt their products and services to users’ real needs. This paper presents the approach used to define and evaluate parametric cognitive models that describe interaction and usage of ICT by people with aging- and disability-derived functional impairments. A multisensorial training platform was used to train, based on real user measurements in real conditions, the virtual parameterized user models that act as subjects of the test-bed during all stages of simulated disabilities-friendly ICT-based products design. An analytical study was carried out to identify the relevant cognitive functions involved, together with their corresponding parameters as related to aging- and disability-derived functional impairments. Evaluation of the final cognitive virtual user models in a real application has confirmed that the use of these models produce concrete valuable benefits to the design and testing process of accessible ICT-based applications and services. Parameterization of cognitive virtual user models allows incorporating cognitive and perceptual aspects during the design process. PMID:26907296

Impaired Driving Performance as Evidence of a Magnocellular Deficit in Dyslexia and Visual Stress.

PubMed

Fisher, Carri; Chekaluk, Eugene; Irwin, Julia

2015-11-01

High comorbidity and an overlap in symptomology have been demonstrated between dyslexia and visual stress. Several researchers have hypothesized an underlying or causal influence that may account for this relationship. The magnocellular theory of dyslexia proposes that a deficit in visuo-temporal processing can explain symptomology for both disorders. If the magnocellular theory holds true, individuals who experience symptomology for these disorders should show impairment on a visuo-temporal task, such as driving. Eighteen male participants formed the sample for this study. Self-report measures assessed dyslexia and visual stress symptomology as well as participant IQ. Participants completed a drive simulation in which errors in response to road signs were measured. Bivariate correlations revealed significant associations between scores on measures of dyslexia and visual stress. Results also demonstrated that self-reported symptomology predicts magnocellular impairment as measured by performance on a driving task. Results from this study suggest that a magnocellular deficit offers a likely explanation for individuals who report high symptomology across both conditions. While conclusions about the impact of these disorders on driving performance should not be derived from this research alone, this study provides a platform for the development of future research, utilizing a clinical population and on-road driving assessment techniques. Copyright © 2015 John Wiley & Sons, Ltd.

Susceptibility of the MMPI-2-RF neurological complaints and cognitive complaints scales to over-reporting in simulated head injury.

PubMed

Bolinger, Elizabeth; Reese, Caitlin; Suhr, Julie; Larrabee, Glenn J

2014-02-01

We examined the effect of simulated head injury on scores on the Neurological Complaints (NUC) and Cognitive Complaints (COG) scales of the Minnesota Multiphasic Personality Inventory-2 Restructured Form (MMPI-2-RF). Young adults with a history of mild head injury were randomly assigned to simulate head injury or give their best effort on a battery of neuropsychological tests, including the MMPI-2-RF. Simulators who also showed poor effort on performance validity tests (PVTs) were compared with controls who showed valid performance on PVTs. Results showed that both scales, but especially NUC, are elevated in individuals simulating head injury, with medium to large effect sizes. Although both scales were highly correlated with all MMPI-2-RF over-reporting validity scales, the relationship of Response Bias Scale to both NUC and COG was much stronger in the simulators than controls. Even accounting for over-reporting on the MMPI-2-RF, NUC was related to general somatic complaints regardless of group membership, whereas COG was related to both psychological distress and somatic complaints in the control group only. Neither scale was related to actual neuropsychological performance, regardless of group membership. Overall, results provide further evidence that self-reported cognitive symptoms can be due to many causes, not necessarily cognitive impairment, and can be exaggerated in a non-credible manner.

Underwater Electromagnetic Sensor Networks, Part II: Localization and Network Simulations

PubMed Central

Zazo, Javier; Valcarcel Macua, Sergio; Zazo, Santiago; Pérez, Marina; Pérez-Álvarez, Iván; Jiménez, Eugenio; Cardona, Laura; Brito, Joaquín Hernández; Quevedo, Eduardo

2016-01-01

In the first part of the paper, we modeled and characterized the underwater radio channel in shallow waters. In the second part, we analyze the application requirements for an underwater wireless sensor network (U-WSN) operating in the same environment and perform detailed simulations. We consider two localization applications, namely self-localization and navigation aid, and propose algorithms that work well under the specific constraints associated with U-WSN, namely low connectivity, low data rates and high packet loss probability. We propose an algorithm where the sensor nodes collaboratively estimate their unknown positions in the network using a low number of anchor nodes and distance measurements from the underwater channel. Once the network has been self-located, we consider a node estimating its position for underwater navigation communicating with neighboring nodes. We also propose a communication system and simulate the whole electromagnetic U-WSN in the Castalia simulator to evaluate the network performance, including propagation impairments (e.g., noise, interference), radio parameters (e.g., modulation scheme, bandwidth, transmit power), hardware limitations (e.g., clock drift, transmission buffer) and complete MAC and routing protocols. We also explain the changes that have to be done to Castalia in order to perform the simulations. In addition, we propose a parametric model of the communication channel that matches well with the results from the first part of this paper. Finally, we provide simulation results for some illustrative scenarios. PMID:27999309

Impaired carotid baroreflex control of arterial blood pressure in multiple sclerosis.

PubMed

Huang, Mu; Allen, Dustin R; Keller, David M; Fadel, Paul J; Frohman, Elliot M; Davis, Scott L

2016-07-01

Multiple sclerosis (MS), a progressive neurological disease, can lead to impairments in the autonomic control of cardiovascular function. We tested the hypothesis that individuals with relapsing-remitting MS (n = 10; 7 females, 3 males; 13 ± 4 yr from diagnosis) exhibit impaired carotid baroreflex control of blood pressure and heart rate compared with sex, age, and body weight-matched healthy individuals (CON: n = 10; 7 females, 3 males). At rest, 5-s trials of neck pressure (NP; +40 Torr) and neck suction (NS; -60 Torr) were applied to simulate carotid hypotension and hypertension, respectively, while mean arterial pressure (MAP; finger photoplethysmography), heart rate (HR), cardiac output (CO; Modelflow), and total vascular conductance (TVC) were continuously measured. In response to NP, there was a blunted increase in peak MAP responses (MS: 5 ± 2 mmHg) in individuals with MS compared with healthy controls (CON: 9 ± 3 mmHg; P = 0.005), whereas peak HR responses were not different between groups. At the peak MAP response to NP, individuals with MS demonstrated an attenuated decrease in TVC (MS, -10 ± 4% baseline vs. CON, -15 ± 4% baseline, P = 0.012), whereas changes in CO were similar between groups. Following NS, all cardiovascular responses (i.e., nadir MAP and HR and percent changes in CO and TVC) were not different between MS and CON groups. These data suggest that individuals with MS have impaired carotid baroreflex control of blood pressure via a blunted vascular conductance response resulting in a diminished ability to increase MAP in response to a hypotensive challenge. Copyright © 2016 the American Physiological Society.

Brain aging in the canine: a diet enriched in antioxidants reduces cognitive dysfunction.

PubMed

Cotman, Carl W; Head, Elizabeth; Muggenburg, Bruce A; Zicker, S; Milgram, Norton W

2002-01-01

Animal models that simulate various aspects of human brain aging are an essential step in the development of interventions to manage cognitive dysfunction in the elderly. Over the past several years we have been studying cognition and neuropathology in the aged-canine (dog). Like humans, canines naturally accumulate deposits of beta-amyloid (Abeta) in the brain with age. Further, canines and humans share the same Abeta sequence and also first show deposits of the longer Abeta1-42 species followed by the deposition of Abeta1-40. Aged canines like humans also show increased oxidative damage. As a function of age, canines show impaired learning and memory on tasks similar to those used in aged primates and humans. The extent of Abeta deposition correlates with the severity of cognitive dysfunction in canines. To test the hypothesis that a cascade of mechanisms centered on oxidative damage and Abeta results in cognitive dysfunction we have evaluated the cognitive effects of an antioxidant diet in aged canines. The diet resulted in a significant improvement in the ability of aged but not young animals to acquire progressively more difficult learning tasks (e.g. oddity discrimination learning). The canine represent a higher animal model to study the earliest declines in the cognitive continuum that includes age associated memory impairments (AAMI) and mild cognitive impairment (MCI) observed in human aging. Thus, studies in the canine model suggest that oxidative damage impairs cognitive function and that antioxidant treatment can result in significant improvements, supporting the need for further human studies. Copyright 2002 Elsevier Science Inc.

Acute disinhibiting effects of alcohol as a factor in risky driving behavior

PubMed Central

Fillmore, Mark T.; Blackburn, Jaime S.; Harrison, Emily L. R.

2008-01-01

Automobile crash reports show that up to 40% of fatal crashes in the United States involve alcohol and that younger drivers are over-represented. Alcohol use among young drivers is associated with impulsive and risky driving behaviors, such as speeding, which could contribute to their over-representation in alcohol-related crash statistics. Recent laboratory studies show that alcohol increases impulsive behaviors by impairing the drinker’s ability to inhibit inappropriate actions and that this effect can be exacerbated in conflict situations where the expression and inhibition of behavior are equally motivating. The present study tested the hypothesis that this response conflict might also intensify the disruptive effects of alcohol on driving performance. Fourteen subjects performed a simulated driving and a cued go/no-go task that measured their inhibitory control. Conflict was motivated in these tasks by providing equal monetary incentives for slow, careful behavior (e.g., slow driving, inhibiting impulses) and for quick, abrupt behavior (fast driving, disinhibition). Subjects were tested under two alcohol doses (0.65 g/kg and a placebo) that were administered twice: when conflict was present and when conflict was absent. Alcohol interacted with conflict to impair inhibitory control and to increase risky and impaired driving behavior on the drive task. Also, individuals whose inhibitory control was most impaired by alcohol displayed the poorest driving performance under the drug. The study demonstrates potentially serious disruptions to driving performance as a function of alcohol intoxication and response conflict, and points to inhibitory control as an important underlying mechanism. PMID:18325693

Impaired carotid baroreflex control of arterial blood pressure in multiple sclerosis

PubMed Central

Huang, Mu; Allen, Dustin R.; Keller, David M.; Fadel, Paul J.; Frohman, Elliot M.

2016-01-01

Multiple sclerosis (MS), a progressive neurological disease, can lead to impairments in the autonomic control of cardiovascular function. We tested the hypothesis that individuals with relapsing-remitting MS (n = 10; 7 females, 3 males; 13 ± 4 yr from diagnosis) exhibit impaired carotid baroreflex control of blood pressure and heart rate compared with sex, age, and body weight-matched healthy individuals (CON: n = 10; 7 females, 3 males). At rest, 5-s trials of neck pressure (NP; +40 Torr) and neck suction (NS; −60 Torr) were applied to simulate carotid hypotension and hypertension, respectively, while mean arterial pressure (MAP; finger photoplethysmography), heart rate (HR), cardiac output (CO; Modelflow), and total vascular conductance (TVC) were continuously measured. In response to NP, there was a blunted increase in peak MAP responses (MS: 5 ± 2 mmHg) in individuals with MS compared with healthy controls (CON: 9 ± 3 mmHg; P = 0.005), whereas peak HR responses were not different between groups. At the peak MAP response to NP, individuals with MS demonstrated an attenuated decrease in TVC (MS, −10 ± 4% baseline vs. CON, −15 ± 4% baseline, P = 0.012), whereas changes in CO were similar between groups. Following NS, all cardiovascular responses (i.e., nadir MAP and HR and percent changes in CO and TVC) were not different between MS and CON groups. These data suggest that individuals with MS have impaired carotid baroreflex control of blood pressure via a blunted vascular conductance response resulting in a diminished ability to increase MAP in response to a hypotensive challenge. PMID:27075533

Long term impairment of cognitive functions and alterations of NMDAR subunits after continuous microwave exposure.

PubMed

Wang, Hui; Tan, Shengzhi; Xu, Xinping; Zhao, Li; Zhang, Jing; Yao, Binwei; Gao, Yabing; Zhou, Hongmei; Peng, Ruiyun

2017-11-01

The long term effects of continuous microwave exposure cannot be ignored for the simulation of the real environment and increasing concerns about the negative cognitive effects of microwave exposure. In this study, 220 male Wistar rats were exposed by a 2.856GHz radiation source with the average power density of 0, 2.5, 5 and 10mW/cm 2 for 6min/day, 5days/week and up to 6weeks. The MWM task, the EEG analysis, the hippocampus structure observation and the western blot were applied until the 12months after microwave exposure to detect the spatial learning and memory abilities, the cortical electrical activity, changes of hippocampal structure and the NMDAR subunits expressions. Results found that the rats in the 10mW/cm 2 group showed the decline of spatial learning and memory abilities and EEG disorders (the decrease of EEG frequencies, and increase of EEG amplitudes and delta wave powers). Moreover, changes of basic structure and ultrastructure of hippocampus also found in the 10 and 5mW/cm 2 groups. The decrease of NR 2A, 2B and p-NR2B might contribute to the impairment of cognitive functions. Our findings suggested that the continuous microwave exposure could cause the dose-dependent long term impairment of spatial learning and memory, the abnormalities of EEG and the hippocampal structure injuries. The decrease of NMDAR key subunits and phosphorylation of NR 2B might contribute to the cognitive impairment. Copyright © 2017 Elsevier Inc. All rights reserved.

Assessment of a directional microphone array for hearing-impaired listeners.

PubMed

Soede, W; Bilsen, F A; Berkhout, A J

1993-08-01

Hearing-impaired listeners often have great difficulty understanding speech in surroundings with background noise or reverberation. Based on array techniques, two microphone prototypes (broadside and endfire) have been developed with strongly directional characteristics [Soede et al., "Development of a new directional hearing instrument based on array technology," J. Acoust. Soc. Am. 94, 785-798 (1993)]. Physical measurements show that the arrays attenuate reverberant sound by 6 dB (free-field) and can improve the signal-to-noise ratio by 7 dB in a diffuse noise field (measured with a KEMAR manikin). For the clinical assessment of these microphones an experimental setup was made in a sound-insulated listening room with one loudspeaker in front of the listener simulating the partner in a discussion and eight loudspeakers placed on the edges of a cube producing a diffuse background noise. The hearing-impaired subject wearing his own (familiar) hearing aid is placed in the center of the cube. The speech-reception threshold in noise for simple Dutch sentences was determined with a normal single omnidirectional microphone and with one of the microphone arrays. The results of monaural listening tests with hearing impaired subjects show that in comparison with an omnidirectional hearing-aid microphone the broadside and endfire microphone array gives a mean improvement of the speech reception threshold in noise of 7.0 dB (26 subjects) and 6.8 dB (27 subjects), respectively. Binaural listening with two endfire microphone arrays gives a binaural improvement which is comparable to the binaural improvement obtained by listening with two normal ears or two conventional hearing aids.

Development and user validation of driving tasks for a power wheelchair simulator.

PubMed

Archambault, Philippe S; Blackburn, Émilie; Reid, Denise; Routhier, François; Miller, William C

2017-07-01

Mobility is important for participation in daily activities and a power wheelchair (PW) can improve quality of life of individuals with mobility impairments. A virtual reality simulator may be helpful in complementing PW skills training, which is generally seen as insufficient by both clinicians and PW users. To this end, specific, ecologically valid activities, such as entering an elevator and navigating through a shopping mall crowd, have been added to the McGill wheelchair (miWe) simulator through a user-centred approach. The objective of this study was to validate the choice of simulated activities in a group of newly trained PW users. We recruited 17 new PW users, who practiced with the miWe simulator at home for two weeks. They then related their experience through the Short Feedback Questionnaire, the perceived Ease of Use Questionnaire, and semi-structured interviews. Participants in general greatly appreciated their experience with the simulator. During the interviews, this group made similar comments about the activities as our previous group of expert PW users had done. They also insisted on the importance of realism in the miWe activities, for their use in training. A PW simulator may be helpful if it supports the practice of activities in specific contexts (such as a bathroom or supermarket), to complement the basic skills training received in the clinic (such as driving forward, backward, turning, and avoiding obstacles). Implications for Rehabilitation New power wheelchair users appreciate practicing on a virtual reality simulator and find the experience useful when the simulated diving activities are realistic and ecologically valid. User-centred development can lead to simulated power wheelchair activities that adequately capture everyday driving challenges experienced in various environmental contexts.

Effects of SMEAT on the oral health of crewmen (DTO 71-2). [dental hygiene

NASA Technical Reports Server (NTRS)

Brown, L. R.; Wheatcroft, M. G.

1973-01-01

The oral health status of three astronauts was monitored before, during and after a 56-day simulation of the Skylab mission. Laboratory and clinical parameters which are considered to be ultimately related to dental impairments were evaluated. The most notable changes were observed in increased counts of mycoplasma and S. mutans, decreased counts of enteric bacilli, decreased saliva flow rates, increased secretory IgA and salivary lysozyme levels, and increased clinical scores of dental plaque, calculus and inflammation.

Cost-effectiveness of the screening and treatment of diabetic retinopathy. What are the costs of underutilization?

PubMed

Fendrick, A M; Javitt, J C; Chiang, Y P

1992-01-01

Diabetic retinal disease remains a leading cause of visual disability among those of working age. Controlled trials have demonstrated that timely diagnosis and photocoagulation treatment can reduce significantly the likelihood of visual impairment in affected diabetic patients. Using a prospective simulation model, we show that an annual screening and treatment program saves thousands of years of vision and reduces medical expenditures over the lifetime of a cohort of Swedish Type I diabetic patients.

Chromatic dispersion estimation based on heterodyne detection for coherent optical communication systems

NASA Astrophysics Data System (ADS)

Li, Yong; Yang, Aiying; Guo, Peng; Qiao, Yaojun; Lu, Yueming

2018-01-01

We propose an accurate and nondata-aided chromatic dispersion (CD) estimation method involving the use of the cross-correlation function of two heterodyne detection signals for coherent optical communication systems. Simulations are implemented to verify the feasibility of the proposed method for 28-GBaud coherent systems with different modulation formats. The results show that the proposed method has high accuracy for measuring CD and has good robustness against laser phase noise, amplified spontaneous emission noise, and nonlinear impairments.

Functional Performance Testing for Power and Return to Sports

PubMed Central

Manske, Robert; Reiman, Michael

2013-01-01

Context: Functional performance testing of athletes can determine physical limitations that may affect sporting activities. Optimal functional performance testing simulates the athlete’s activity. Evidence Acquisition: A Medline search from 1960 to 2012 was implemented with the keywords functional testing, functional impairment testing, and functional performance testing in the English language. Each author also undertook independent searches of article references. Conclusion: Functional performance tests can bridge the gap between general physical tests and full, unrestricted athletic activity. PMID:24427396

Motor simulation and the coordination of self and other in real-time joint action

PubMed Central

Ticini, Luca F.; Schütz-Bosbach, Simone; Keller, Peter E.

2014-01-01

Joint actions require the integration of simultaneous self- and other-related behaviour. Here, we investigated whether this function is underpinned by motor simulation, that is the capacity to represent a perceived action in terms of the neural resources required to execute it. This was tested in a music performance experiment wherein on-line brain stimulation (double-pulse transcranial magnetic stimulation, dTMS) was employed to interfere with motor simulation. Pianists played the right-hand part of piano pieces in synchrony with a recording of the left-hand part, which had (Trained) or had not (Untrained) been practiced beforehand. Training was assumed to enhance motor simulation. The task required adaptation to tempo changes in the left-hand part that, in critical conditions, were preceded by dTMS delivered over the right primary motor cortex. Accuracy of tempo adaptation following dTMS or sham stimulations was compared across Trained and Untrained conditions. Results indicate that dTMS impaired tempo adaptation accuracy only during the perception of trained actions. The magnitude of this interference was greater in empathic individuals possessing a strong tendency to adopt others’ perspectives. These findings suggest that motor simulation provides a functional resource for the temporal coordination of one’s own behaviour with others in dynamic social contexts. PMID:23709353

A controlled study of a simulated workplace laboratory for adults with attention deficit hyperactivity disorder.

PubMed

Fried, Ronna; Surman, Craig; Hammerness, Paul; Petty, Carter; Faraone, Stephen; Hyder, Laran; Westerberg, Diana; Small, Jacqueline; Corkum, Lyndsey; Claudat, Kim; Biederman, Joseph

2012-12-30

Despite an extant literature documenting that adults with attention-deficit/hyperactivity disorder (ADHD) are at increased risk for significant difficulties in the workplace, there is little documentation of the underlying factors associated with these impairments. The main aim of this study was to examine specific deficiencies associated with ADHD on workplace performance in a simulated workplace laboratory relative to controls. Participants were 56 non-medicated young adults with DSM-IV ADHD and 63 age- and sex-matched controls without ADHD. Participants spent 10h in a workplace simulation laboratory. Areas assessed included: (1) simulated tasks documented in a government report (SCANS) often required in workplace settings (taxing vigilance; planning; cooperation; attention to detail), (2) observer ratings, and (3) self-reports. Robust findings were found in the statistically significant differences on self-report of ADHD symptoms found between participants with ADHD and controls during all workplace tasks and periods of the workday. Task performance was found to be deficient in a small number of areas, and there were a few statistically significant differences identified by observer ratings. Symptoms reported by participants with ADHD in the simulation including internal restlessness, intolerance of boredom and difficulty maintaining vigilance were significant and could adversely impact workplace performance over the long-term. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Inter-identity amnesia in dissociative identity disorder: a simulated memory impairment?

PubMed

Huntjens, Rafaële J C; Peters, Madelon L; Woertman, Liesbeth; Bovenschen, Loes M; Martin, Roy C; Postma, Albert

2006-06-01

Although included in the current edition of the DSM, there does not seem to be consensus among mental health professionals regarding the diagnostic status and scientific validity of dissociative identity disorder (DID). This study was aimed at the detection of simulation of inter-identity amnesia in DID. A sample of 22 DID patients was included, together with a matched control sample of subjects instructed to simulate inter-identity amnesia, a guessor group that had no knowledge of the stimulus material and a normal control group. A multiple-choice recognition test was included. The rate of incorrect answers was determined. Moreover, the specific simulation strategy used was examined by providing subjects with a range of choices that varied in extent of disagreement with the correct answer and determining whether plausible or implausible answer alternatives were selected. On the recognition test DID patients selected incorrect answers above chance like simulators. Patients thus seem to use their knowledge of the correct answer in determining their given answer. They were not characterized by a well-thought-out simulating behaviour style, as indicated by the differences in selection of specific answer alternatives found between patients and simulators. DID patients were found not to be characterized by an actual memory retrieval inability, in contrast to their subjective reports. Instead, it is suggested that DID may more accurately be considered a disorder characterized by meta-memory problems, holding incorrect beliefs about their own memory functioning.