On the electromagnetic fields, Poynting vector, and peak power radiated by lightning return strokes

NASA Technical Reports Server (NTRS)

Krider, E. P.

1992-01-01

The initial radiation fields, Poynting vector, and total electromagnetic power that a vertical return stroke radiates into the upper half space have been computed when the speed of the stroke, nu, is a significant fraction of the speed of light, c, assuming that at large distances and early times the source is an infinitesimal dipole. The initial current is also assumed to satisfy the transmission-line model with a constant nu and to be perpendicular to an infinite, perfectly conducting ground. The effect of a large nu is to increase the radiation fields by a factor of (1-beta-sq cos-sq theta) exp -1, where beta = nu/c and theta is measured from the vertical, and the Poynting vector by a factor of (1-beta-sq cos-sq theta) exp -2.

Validation of simplified centre of mass models during gait in individuals with chronic stroke.

PubMed

Huntley, Andrew H; Schinkel-Ivy, Alison; Aqui, Anthony; Mansfield, Avril

2017-10-01

The feasibility of using a multiple segment (full-body) kinematic model in clinical gait assessment is difficult when considering obstacles such as time and cost constraints. While simplified gait models have been explored in healthy individuals, no such work to date has been conducted in a stroke population. The aim of this study was to quantify the errors of simplified kinematic models for chronic stroke gait assessment. Sixteen individuals with chronic stroke (>6months), outfitted with full body kinematic markers, performed a series of gait trials. Three centre of mass models were computed: (i) 13-segment whole-body model, (ii) 3 segment head-trunk-pelvis model, and (iii) 1 segment pelvis model. Root mean squared error differences were compared between models, along with correlations to measures of stroke severity. Error differences revealed that, while both models were similar in the mediolateral direction, the head-trunk-pelvis model had less error in the anteroposterior direction and the pelvis model had less error in the vertical direction. There was some evidence that the head-trunk-pelvis model error is influenced in the mediolateral direction for individuals with more severe strokes, as a few significant correlations were observed between the head-trunk-pelvis model and measures of stroke severity. These findings demonstrate the utility and robustness of the pelvis model for clinical gait assessment in individuals with chronic stroke. Low error in the mediolateral and vertical directions is especially important when considering potential stability analyses during gait for this population, as lateral stability has been previously linked to fall risk. Copyright © 2017 Elsevier Ltd. All rights reserved.

Practice variation in the structure of stroke rehabilitation in four rehabilitation centres in the Netherlands.

PubMed

Groeneveld, Iris F; Meesters, Jorit J L; Arwert, Henk J; Roux-Otter, Nienke; Ribbers, Gerard M; van Bennekom, Coen A M; Goossens, Paulien H; Vliet Vlieland, Thea P M

2016-03-01

To describe practice variation in the structure of stroke rehabilitation in 4 specialized multidisciplinary rehabilitation centres in the Netherlands. A multidisciplinary expert group formulated a set of 23 elements concerning the structure of inpatient and outpatient stroke rehabilitation, categorized into 4 domains: admission-related (n = 7), treatment-related (n = 10), client involvement-related (n = 2), and facilities-related (n = 4). In a cross-sectional study in 4 rehabilitation centres data on the presence and content of these elements were abstracted from treatment programmes and protocols. In a structured expert meeting consensus was reached on the presence of practice variation per element. Practice variation was observed in 22 of the 23 structure elements. The element "strategies for patient involvement" appeared similar in all rehabilitation centres, whereas differences were found in the elements regarding admission, exclusion and discharge criteria, patient subgroups, care pathways, team meetings, clinical assessments, maximum time to admission, aftercare and return to work modules, health professionals, treatment facilities, and care-giver involvement. Practice variation was found in a wide range of aspects of the structure of stroke rehabilitation.

A Multi-Week Behavioral Sampling Tag for Sound Effects Studies: Design Trade-Offs and Prototype Evaluation

DTIC Science & Technology

2014-09-30

to establish the performance of algorithms detecting dives, strokes , clicks, respiration and gait changes. We have also found that a combination of...whale click count, total click count, vocal duration, SOC2 depth, EOC3 depth) Descent 40 bits (duration, vertical speed, stroke count 0...100 m, stroke count 100-400 m, OBDA4, sum sr35) Bottom 26 bits (movement index6, OBDA, jerk events7, median jerk depth) Ascent

Lumbar load attenuation for rotorcraft occupants using a design methodology for the seat impact energy-absorbing system

NASA Astrophysics Data System (ADS)

Moradi, Rasoul; Beheshti, Hamid K.; Lankarani, Hamid M.

2012-12-01

Aircraft occupant crash-safety considerations require a minimum cushion thickness to limit the relative vertical motion of the seat-pelvis during high vertical impact loadings in crash landings or accidents. In military aircraft and helicopter seat design, due to the potential for high vertical accelerations in crash scenarios, the seat system must be provided with an energy absorber to attenuate the acceleration level sustained by the occupants. Because of the limited stroke available for the seat structure, the design of the energy absorber becomes a trade-off problem between minimizing the stroke and maximizing the energy absorption. The available stroke must be used to prevent bottoming out of the seat as well as to absorb maximum impact energy to protect the occupant. In this study, the energy-absorbing system in a rotorcraft seat design is investigated using a mathematical model of the occupant/seat system. Impact theories between interconnected bodies in multibody mechanical systems are utilized to study the impact between the seat pan and the occupant. Experimental responses of the seat system and the occupant are utilized to validate the results from this study for civil and military helicopters according to FAR 23 and 25 and MIL-S-58095 requirements. A model for the load limiter is proposed to minimize the lumbar load for the occupant by minimizing the relative velocity between the seat pan and the occupant's pelvis. The modified energy absorber/load limiter is then implemented for the seat structure so that it absorbs the energy of impact in an effective manner and below the tolerable limit for the occupant in a minimum stroke. Results show that for a designed stroke, the level of occupant lumbar spine injury would be significantly attenuated using this modified energy-absorber system.

Aerodynamic forces and flow structures of the leading edge vortex on a flapping wing considering ground effect.

PubMed

Van Truong, Tien; Byun, Doyoung; Kim, Min Jun; Yoon, Kwang Joon; Park, Hoon Cheol

2013-09-01

The aim of this work is to provide an insight into the aerodynamic performance of the beetle during takeoff, which has been estimated in previous investigations. We employed a scaled-up electromechanical model flapping wing to measure the aerodynamic forces and the three-dimensional flow structures on the flapping wing. The ground effect on the unsteady forces and flow structures were also characterized. The dynamically scaled wing model could replicate the general stroke pattern of the beetle's hind wing kinematics during takeoff flight. Two wing kinematic models have been studied to examine the influences of wing kinematics on unsteady aerodynamic forces. In the first model, the angle of attack is asymmetric and varies during the translational motion, which is the flapping motion of the beetle's hind wing. In the second model, the angle of attack is constant during the translational motion. The instantaneous aerodynamic forces were measured for four strokes during the beetle's takeoff by the force sensor attached at the wing base. Flow visualization provided a general picture of the evolution of the three-dimensional leading edge vortex (LEV) on the beetle hind wing model. The LEV is stable during each stroke, and increases radically from the root to the tip, forming a leading-edge spiral vortex. The force measurement results show that the vertical force generated by the hind wing is large enough to lift the beetle. For the beetle hind wing kinematics, the total vertical force production increases 18.4% and 8.6% for the first and second strokes, respectively, due to the ground effect. However, for the model with a constant angle of attack during translation, the vertical force is reduced during the first stroke. During the third and fourth strokes, the ground effect is negligible for both wing kinematic patterns. This finding suggests that the beetle's flapping mechanism induces a ground effect that can efficiently lift its body from the ground during takeoff.

Uncovering the Rosetta Stone: Report from the First Annual Conference on Key Elements in Translating Stroke Therapeutics from Pre-Clinical to Clinical.

PubMed

Bix, Gregory J; Fraser, Justin F; Mack, William J; Carmichael, S Thomas; Perez-Pinzon, Miguel; Offner, Halina; Sansing, Lauren; Bosetti, Francesca; Ayata, Cenk; Pennypacker, Keith R

2018-06-01

The first annual Stroke Translational Research Advancement Workshop (STRAW), entitled "Uncovering the Rosetta Stone: Key Elements in Translating Stroke Therapeutics from Pre-Clinical to Clinical" was held at the University of Kentucky on October 4-5, 2017. This workshop was organized by the Center for Advanced Translational Stroke Science. The workshop consisted of 2 days of activities. These included three presentations establishing the areas of research in stroke therapeutics, discussing the routes for translation from bench to bedside, and identifying successes and failures in the field. On day 2, grant funding opportunities and goals for the National Institute for Neurological Diseases and Stroke were presented. In addition, the meeting also included break-out sessions designed to connect researchers in areas of stroke, and to foster potential collaborations. Finally, the meeting concluded with an open discussion among attendees led by a panel of experts.

[Vertical integration--an important component of rehabilitation of patients with stroke].

PubMed

Sereda, V G; Drygant, L P; Ingula, N I; Kravchuk, N A; Tkachenko, V V; Babirad, A M; Sizina, A V; Titenko, Iu I; Nedashkovskaia, V A; Andrusenko, A S; Sheremet, A E; Kushpiĭ, O V; Mogorita, O L; Matsikevich, V V; Sukhoruchkin, Iu A; Sachko, Iu Iu

2012-01-01

Today it is proved that the reduction of mortality from cardiovascular disease is achieved through the implementation of a coordinated set of measures, the most important of which is to increase public awareness of the risk factors for cardiovascular diseases and their prevention, implementation of effective prevention programs and improve the system of care for stroke.

Inter-rater reliability of data elements from a prototype of the Paul Coverdell National Acute Stroke Registry

PubMed Central

Reeves, Mathew J; Mullard, Andrew J; Wehner, Susan

2008-01-01

Background The Paul Coverdell National Acute Stroke Registry (PCNASR) is a U.S. based national registry designed to monitor and improve the quality of acute stroke care delivered by hospitals. The registry monitors care through specific performance measures, the accuracy of which depends in part on the reliability of the individual data elements used to construct them. This study describes the inter-rater reliability of data elements collected in Michigan's state-based prototype of the PCNASR. Methods Over a 6-month period, 15 hospitals participating in the Michigan PCNASR prototype submitted data on 2566 acute stroke admissions. Trained hospital staff prospectively identified acute stroke admissions, abstracted chart information, and submitted data to the registry. At each hospital 8 randomly selected cases were re-abstracted by an experienced research nurse. Inter-rater reliability was estimated by the kappa statistic for nominal variables, and intraclass correlation coefficient (ICC) for ordinal and continuous variables. Factors that can negatively impact the kappa statistic (i.e., trait prevalence and rater bias) were also evaluated. Results A total of 104 charts were available for re-abstraction. Excellent reliability (kappa or ICC > 0.75) was observed for many registry variables including age, gender, black race, hemorrhagic stroke, discharge medications, and modified Rankin Score. Agreement was at least moderate (i.e., 0.75 > kappa ≥; 0.40) for ischemic stroke, TIA, white race, non-ambulance arrival, hospital transfer and direct admit. However, several variables had poor reliability (kappa < 0.40) including stroke onset time, stroke team consultation, time of initial brain imaging, and discharge destination. There were marked systematic differences between hospital abstractors and the audit abstractor (i.e., rater bias) for many of the data elements recorded in the emergency department. Conclusion The excellent reliability of many of the data elements supports the use of the PCNASR to monitor and improve care. However, the poor reliability for several variables, particularly time-related events in the emergency department, indicates the need for concerted efforts to improve the quality of data collection. Specific recommendations include improvements to data definitions, abstractor training, and the development of ED-based real-time data collection systems. PMID:18547421

Muscle activity adapts to anti-gravity posture during pedalling in persons with post-stroke hemiplegia.

PubMed

Brown, D A; Kautz, S A; Dairaghi, C A

1997-05-01

With hemiplegia following stroke, a person's movement response to anti-gravity posture often appears rigid and inflexible, exacerbating the motor dysfunction. A major determinant of pathological movement in anti-gravity postures is the failure to adapt muscle-activity patterns automatically to changes in posture. The aim of the present study was to determine whether the impaired motor performance observed when persons with hemiplegia pedal in a horizontal position is exacerbated at more vertical anti-gravity body orientations. Twelve healthy elderly subjects and 17 subjects with chronic (> 6 months) post-stroke hemiplegia participated in the study. Subjects pedalled a modified ergometer at different body orientations (from horizontal to vertical), maintaining the same workload, cadence, and hip and knee kinematics. Pedal reaction forces, and crank and pedal kinematics, were measured and then used to calculate the work done by each leg and their net positive and negative components. The EMG was recorded from four leg muscles (tibialis anterior, medial gastrocnemius, rectus femoris and biceps femoris). The main result from this study was that impaired plegic leg performance, as measured by net negative work done by the plegic leg and abnormal early rectus femoris activity, was exacerbated at the most vertical body orientations. However, contrary to the belief that muscle activity cannot adapt to anti-gravity postures, net positive work increased appropriately and EMG activity in all muscles showed modulated levels of activity similar to those in elderly control subjects. These results support the hypothesis that increased verticality exacerbates the already impaired movement performance. Yet, much of the motor response to verticality was flexible and appropriate, given the mechanics of the task.

Observing relationships between lightning and cloud profiles by means of a satellite-borne cloud radar

NASA Astrophysics Data System (ADS)

Buiat, Martina; Porcù, Federico; Dietrich, Stefano

2017-01-01

Cloud electrification and related lightning activity in thunderstorms have their origin in the charge separation and resulting distribution of charged iced particles within the cloud. So far, the ice distribution within convective clouds has been investigated mainly by means of ground-based meteorological radars. In this paper we show how the products from Cloud Profiling Radar (CPR) on board CloudSat, a polar satellite of NASA's Earth System Science Pathfinder (ESSP), can be used to obtain information from space on the vertical distribution of ice particles and ice content and relate them to the lightning activity. The analysis has been carried out, focusing on 12 convective events over Italy that crossed CloudSat overpasses during significant lightning activity. The CPR products considered here are the vertical profiles of cloud ice water content (IWC) and the effective radius (ER) of ice particles, which are compared with the number of strokes as measured by a ground lightning network (LINET). Results show a strong correlation between the number of strokes and the vertical distribution of ice particles as depicted by the 94 GHz CPR products: in particular, cloud upper and middle levels, high IWC content and relatively high ER seem to be favourable contributory causes for CG (cloud to ground) stroke occurrence.

Unsteady aerodynamic force mechanisms of a hoverfly hovering with a short stroke-amplitude

NASA Astrophysics Data System (ADS)

Zhu, Hao Jie; Sun, Mao

2017-08-01

Hovering insects require a rather large lift coefficient. Many insects hover with a large stroke amplitude (120°-170°), and it has been found that the high lift is mainly produced by the delayed-stall mechanism. However, some insects hover with a small stroke amplitude (e.g., 65°). The delayed-stall mechanism might not work for these insects because the wings travel only a very short distance in a stroke, and other aerodynamic mechanisms must be operating. Here we explore the aerodynamic mechanisms of a hoverfly hovering with an inclined stroke plane and a small stroke amplitude (65.6°). The Navier-Stokes equations are numerically solved to give the flows and forces and the theory of vorticity dynamics used to reveal the aerodynamic mechanisms. The majority of the weight-supporting vertical force is produced in the mid portion of the downstroke, a short period (about 26% of the stroke cycle) in which the vertical force coefficient is larger than 4. The force is produced using a new mechanism, the "paddling mechanism." During the short period, the wing moves rapidly downward and forward at a large angle of attack (about 48°), and strong counter clockwise vorticity is produced continuously at the trailing edge and clockwise vorticity at the leading edge, resulting in a large time rate of change in the first moment of vorticity, hence the large aerodynamic force. It is interesting to note that with the well known delayed stall mechanism, the force is produced by the relative motion of two vortices of opposite sign, while in the "paddling mechanism," it is produced by generating new vortices of opposite sign at different locations.

Language-specific dysgraphia in Korean patients with right brain stroke: influence of unilateral spatial neglect.

PubMed

Jang, Dae-Hyun; Kim, Min-Wook; Park, Kyoung Ha; Lee, Jae Woo

2015-03-01

The purpose of the present study was to investigate the relationship between Korean language-specific dysgraphia and unilateral spatial neglect in 31 right brain stroke patients. All patients were tested for writing errors in spontaneous writing, dictation, and copying tests. The dysgraphia was classified into visuospatial omission, visuospatial destruction, syllabic tilting, stroke omission, stroke addition, and stroke tilting. Twenty-three (77.4%) of the 31 patients made dysgraphia and 18 (58.1%) demonstrated unilateral spatial neglect. The visuospatial omission was the most common dysgraphia followed by stroke addition and omission errors. The highest number of errors was made in the copying and the least was in the spontaneous writing test. Patients with unilateral spatial neglect made a significantly higher number of dysgraphia in the copying test than those without. We identified specific dysgraphia features such as a right side space omission and a vertical stroke addition in Korean right brain stroke patients. In conclusion, unilateral spatial neglect influences copy writing system of Korean language in patients with right brain stroke.

Postural disorders and spatial neglect in stroke patients: a strong association.

PubMed

Pérennou, Dominic

2006-01-01

In this paper we analyse the arguments for a strong association between spatial neglect and postural disorders and attempt to better understand the mechanisms which underlie that. We first provide a general overview of the available tools for a rational assessment of postural control in a clinical context. We then analyse the arguments in favour of a close relationship, although not necessarily causal, between spatial neglect and: 1) body orientation with respect to gravity (including verticality perception i.e. the visual vertical, the haptic vertical, and the postural vertical); 2) body stabilisation with respect to the base of support; 3) posturographic features of stroke patients; 4) and finally their postural disability in daily life. This second part of the paper is based both on the literature review and on results of our current research. Neglect patients show a dramatic postural disability, due both to problems in body orientation with respect to gravity and to problems in body stabilisation. It might be that these problems are partly caused by a neglect phenomenon bearing on graviceptive (somaesthetic > vestibular) and visual information serving postural control. This could correspond to a kind of postural neglect involving both the bodily and nonbodily domains of spatial neglect. The existence of distorsion(s) in the body scheme are also probably involved, especially to explain the weight-bearing asymmetry in standing, and probably an impaired multisegmental postural coordination leading to an impaired body stabilisation. The present paper explains why neglect patients show longer/worse recovery of postural-walking autonomy than other stroke patients.

Gravity receptors in a microcrustacean water flea - Sensitivity of antennal-socket setae in Daphnia magna

NASA Technical Reports Server (NTRS)

Meyers, D. G.; Farmer, J. M.

1982-01-01

Gravity receptors of Dephnia magna were discovered on the basal segment of the swimming antennae and were shown to respond to upward water currents that pass the animal as it sinks between swimming strokes. Sensitivity of the gravity perceiving mechanism was tested by subjecting daphnids to a series of five decreasingly dense aqueous solutions (neutral density to water) in darkness (to avoid visual cues). Three-dimensional, video analysis of body position (pitch, yaw and roll) and swimming path (hop and sink, vertical and horizontal patterns) revealed a gradual threshold that occurred near a density difference between the animal and its environment of less than 0.25%. Because daphnids do not sink but continue to slide after stroking in the increased density solutions, gravity perception appears to occur during a vertical swing of the longitudinal body axis to the vertical plane, about their center of gravity, and, thereby, implies a multidirectional sensitivity for the antennal-socket setae.

Kinematics of Signature Writing in Healthy Aging*

PubMed Central

Caligiuri, Michael P.; Kim, Chi; Landy, Kelly M.

2014-01-01

Forensic document examiners (FDE) called upon to distinguish a genuine from a forged signature of an elderly person are often required to consider the question of age-related deterioration and whether the available exemplars reliably capture the natural effects of aging of the original writer. An understanding of the statistical relationship between advanced age and handwriting movements can reduce the uncertainty that may exist in an examiner’s approach to questioned signatures formed by elderly writers. The primary purpose of this study was to systematically examine age-related changes in signature kinematics in healthy writers. Forty-two healthy subjects between the ages of 60–91 years participated in this study. Signatures were recorded using a digitizing tablet and commercial software was used to examine the temporal and spatial stroke kinematics and pen pressure. Results indicated that vertical stroke duration and dysfluency increased with age, whereas vertical stroke amplitude and velocity decreased with age. Pen pressure decreased with age. We found that a linear model characterized the best-fit relationship between advanced age and handwriting movement parameters for signature formation. Male writers exhibited stronger age effects than female writers, especially for pen pressure and stroke dysfluency. The present study contributes to an understanding of how advanced age alters signature formation in otherwise healthy adults. PMID:24673648

Vertical discretization with finite elements for a global hydrostatic model on the cubed sphere

NASA Astrophysics Data System (ADS)

Yi, Tae-Hyeong; Park, Ja-Rin

2017-06-01

A formulation of Galerkin finite element with basis-spline functions on a hybrid sigma-pressure coordinate is presented to discretize the vertical terms of global Eulerian hydrostatic equations employed in a numerical weather prediction system, which is horizontally discretized with high-order spectral elements on a cubed sphere grid. This replaces the vertical discretization of conventional central finite difference that is first-order accurate in non-uniform grids and causes numerical instability in advection-dominant flows. Therefore, a model remains in the framework of Galerkin finite elements for both the horizontal and vertical spatial terms. The basis-spline functions, obtained from the de-Boor algorithm, are employed to derive both the vertical derivative and integral operators, since Eulerian advection terms are involved. These operators are used to discretize the vertical terms of the prognostic and diagnostic equations. To verify the vertical discretization schemes and compare their performance, various two- and three-dimensional idealized cases and a hindcast case with full physics are performed in terms of accuracy and stability. It was shown that the vertical finite element with the cubic basis-spline function is more accurate and stable than that of the vertical finite difference, as indicated by faster residual convergence, fewer statistical errors, and reduction in computational mode. This leads to the general conclusion that the overall performance of a global hydrostatic model might be significantly improved with the vertical finite element.

Characteristics of lightning flashes generating dancing sprites above thunderstorms

NASA Astrophysics Data System (ADS)

Soula, Serge; Mlynarczyk, Janusz; Füllekrug, Martin; Pineda, Nicolau; Georgis, Jean-François; van der Velde, Oscar; Montanyà, Joan; Fabro, Ferran

2017-04-01

During the night of October 29-30, 2013, a low-light video camera at Pic du Midi (2877 m) in the French Pyrénées, recorded TLEs above a very active storm over the Mediterranean Sea. The minimum cloud top temperature reached -73˚ C at ˜1600 UTC while its cloud to ground (CG) flash rate reached ˜30 fl min-1. Some sprite events with long duration are classified as dancing sprites. We analyze in detail the temporal evolution and estimated location of sprite elements for two cases of these events. They consist in series of sprite sequences with a duration that exceeds 1 second. By associating the cloud structure, the lightning activity, the electric field radiated in a broad range of low frequencies and the current moment waveform of the lightning strokes, some findings are highlighted: (i) In each series, successive sprite sequences reflect the occurrence time and location of individual positive lightning strokes across the stratiform region. (ii) The longer time-delayed (> 20 ms) sprite elements correspond to the lower impulsive charge moment changes (iCMC) of the parent stroke (< 200 C km) and they are shifted few tens of kilometres from their SP+CG stroke. However, both short and long time-delayed sprite elements also occur after strokes that produce a large iCMC and that are followed by a continuing current. (iii) The long time-delayed sprite elements produced during the continuing current correspond to surges in the current moment waveform. They occur sometimes at an altitude apparently lower than the previous short time-delayed sprite elements, possibly because of the lowered altitude of the ionosphere potential. (iv) The largest and brightest sprite elements produce significant current signatures, visible when their delay is not too short (˜3-5 ms).

Rules to fly by: pigeons navigating horizontal obstacles limit steering by selecting gaps most aligned to their flight direction.

PubMed

Ros, Ivo G; Bhagavatula, Partha S; Lin, Huai-Ti; Biewener, Andrew A

2017-02-06

Flying animals must successfully contend with obstacles in their natural environments. Inspired by the robust manoeuvring abilities of flying animals, unmanned aerial systems are being developed and tested to improve flight control through cluttered environments. We previously examined steering strategies that pigeons adopt to fly through an array of vertical obstacles (VOs). Modelling VO flight guidance revealed that pigeons steer towards larger visual gaps when making fast steering decisions. In the present experiments, we recorded three-dimensional flight kinematics of pigeons as they flew through randomized arrays of horizontal obstacles (HOs). We found that pigeons still decelerated upon approach but flew faster through a denser array of HOs compared with the VO array previously tested. Pigeons exhibited limited steering and chose gaps between obstacles most aligned to their immediate flight direction, in contrast to VO navigation that favoured widest gap steering. In addition, pigeons navigated past the HOs with more variable and decreased wing stroke span and adjusted their wing stroke plane to reduce contact with the obstacles. Variability in wing extension, stroke plane and wing stroke path was greater during HO flight. Pigeons also exhibited pronounced head movements when negotiating HOs, which potentially serve a visual function. These head-bobbing-like movements were most pronounced in the horizontal (flight direction) and vertical directions, consistent with engaging motion vision mechanisms for obstacle detection. These results show that pigeons exhibit a keen kinesthetic sense of their body and wings in relation to obstacles. Together with aerodynamic flapping flight mechanics that favours vertical manoeuvring, pigeons are able to navigate HOs using simple rules, with remarkable success.

Rules to fly by: pigeons navigating horizontal obstacles limit steering by selecting gaps most aligned to their flight direction

PubMed Central

Ros, Ivo G.; Bhagavatula, Partha S.; Lin, Huai-Ti

2017-01-01

Flying animals must successfully contend with obstacles in their natural environments. Inspired by the robust manoeuvring abilities of flying animals, unmanned aerial systems are being developed and tested to improve flight control through cluttered environments. We previously examined steering strategies that pigeons adopt to fly through an array of vertical obstacles (VOs). Modelling VO flight guidance revealed that pigeons steer towards larger visual gaps when making fast steering decisions. In the present experiments, we recorded three-dimensional flight kinematics of pigeons as they flew through randomized arrays of horizontal obstacles (HOs). We found that pigeons still decelerated upon approach but flew faster through a denser array of HOs compared with the VO array previously tested. Pigeons exhibited limited steering and chose gaps between obstacles most aligned to their immediate flight direction, in contrast to VO navigation that favoured widest gap steering. In addition, pigeons navigated past the HOs with more variable and decreased wing stroke span and adjusted their wing stroke plane to reduce contact with the obstacles. Variability in wing extension, stroke plane and wing stroke path was greater during HO flight. Pigeons also exhibited pronounced head movements when negotiating HOs, which potentially serve a visual function. These head-bobbing-like movements were most pronounced in the horizontal (flight direction) and vertical directions, consistent with engaging motion vision mechanisms for obstacle detection. These results show that pigeons exhibit a keen kinesthetic sense of their body and wings in relation to obstacles. Together with aerodynamic flapping flight mechanics that favours vertical manoeuvring, pigeons are able to navigate HOs using simple rules, with remarkable success. PMID:28163883

Aquatic wing flapping at low Reynolds numbers: swimming kinematics of the Antarctic pteropod, Clione antarctica.

PubMed

Borrell, Brendan J; Goldbogen, Jeremy A; Dudley, Robert

2005-08-01

We studied swimming kinematics of the Antarctic pteropod, Clione antarctica, to investigate how propulsive forces are generated by flexible oscillating appendages operating at low Reynolds numbers (1025) exhibited gliding during the recovery phase of each half-stroke. Maximum translational and rotational accelerations of the body occurred at the initiation of each power phase, suggesting that rotational circulation, the acceleration reaction, and wake recapture may all potentially contribute to vertical force production. Individual contributions of these mechanisms cannot, however, be assessed from these kinematic data alone. During recovery phases of each half-stroke, C. antarctica minimized adverse drag forces by orienting the wings parallel to flow and by moving them along the body surface, possibly taking advantage of boundary layer effects. Vertical force production was altered through changes in the hydrodynamic angle of attack of the wing that augmented drag during the power phase of each half-stroke. At higher translational velocities of the body, the inclination of the power phase also became more nearly vertical. These results indicate that, in addition to serotonin-mediated modulation of wingbeat frequency reported previously in Clione, geometric alteration of wingbeat kinematics offers a precise means of controlling swimming forces.

Effect of Punch Stroke on Deformation During Sheet Forming Through Finite Element

NASA Astrophysics Data System (ADS)

Akinlabi, Stephen; Akinlabi, Esther

2017-08-01

Forming is one of the traditional methods of making shapes, bends and curvature in metallic components during a fabrication process. Mechanical forming, in particular, employs the use of a punch, which is pressed against the sheet material to be deformed into a die by the application of an external force. This study reports on the finite element analysis of the effects of punch stroke on the resulting sheet deformation, which is directly a function of the structural integrity of the formed components for possible application in the automotive industry. The results show that punch stroke is directly proportional to the resulting bend angle of the formed components. It was further revealed that the developed plastic strain increases as the punch stroke increases.

Do post-stroke patients benefit from robotic verticalization? A pilot-study focusing on a novel neurophysiological approach.

PubMed

Calabrò, Rocco Salvatore; Naro, Antonino; Russo, Margherita; Leo, Antonino; Balletta, Tina; Saccá, Ileana; De Luca, Rosaria; Bramanti, Placido

2015-01-01

Tilt-table equipped with the dynamic foot-support (ERIGO) and the functional electric stimulation could be a safe and suitable device for stabilization of vital signs, increasing patient's motivation for further recovery, decreasing the duration of hospitalization, and accelerating the adaptation to vertical posture in bedridden patients with brain-injury. Moreover, it is conceivable that verticalization may improve cognitive functions, and induce plastic changes at sensory motor and vestibular system level that may in turn facilitate motor functional recovery. To test the safety and effectiveness of ERIGO treatment on motor and cognitive functions, cortical plasticity within vestibular and sensory-motor systems in a bedridden post-stroke sample. 20 patients were randomly divided in two groups that performed ERIGO training (30 sessions) (G1) or physiotherapist-assisted verticalization training (same duration) (G2), beyond conventional neurorehabilitation treatment. Motor and cognitive functions as well as sensory-motor and vestibular system plasticity were investigated either before (T0) or after (T1) the rehabilitative protocols. Both the verticalization treatments were well-tolerated. Notably, the G1 patients had a significant improvement in cognitive function (p = 0.03), global motor function (p = 0.006), sensory-motor (p < 0.001) and vestibular system plasticity (p = 0.02) as compared to G2. ERIGO training could be a valuable tool for the adaptation to the vertical position with a better global function improvement, as also suggested by the sensory-motor and vestibular system plasticity induction.

Dancing sprites: Detailed analysis of two case studies

NASA Astrophysics Data System (ADS)

Soula, Serge; Mlynarczyk, Janusz; Füllekrug, Martin; Pineda, Nicolau; Georgis, Jean-François; van der Velde, Oscar; Montanyà, Joan; Fabró, Ferran

2017-03-01

On 29-30 October 2013, a low-light video camera installed at Pic du Midi (2877 m), recorded transient luminous events above a very active storm over the Mediterranean Sea. The minimum cloud top temperature reached -73°C, while its cloud to ground (CG) flash rate exceeded 30 fl min-1. Some sprite events have long duration and resemble to dancing sprites. We analyze in detail the temporal evolution and estimated location of two series of sprite sequences, as well as the cloud structure, the lightning activity, the electric field radiated in a broad range of low frequencies, and the current moment waveform of the lightning strokes. (i) In each series, successive sprite sequences reflect time and location of corresponding positive lightning strokes across the stratiform region. (ii) The longer time-delayed (>20 ms) sprite elements correspond to the lower impulsive charge moment changes (iCMC) of the parent strokes (<200 C km), and they are shifted few tens of kilometers from their SP + CG stroke. However, both short and long time-delayed sprite elements also occur after strokes that produce a large iCMC and that are followed by a continuing current. (iii) The long time-delayed sprite elements during the continuing current correspond to surges in the current moment waveform. They occur sometimes at an altitude apparently lower than the previous short time-delayed sprite elements, possibly because of changes in the local conductivity. (iv) The largest and brightest sprite elements produce significant current signatures, visible when their delay is not too short ( 3-5 ms).

Revealing the Penumbra through Imaging Elemental Markers of Cellular Metabolism in an Ischemic Stroke Model.

PubMed

Pushie, M Jake; Crawford, Andrew M; Sylvain, Nicole J; Hou, Huishu; Hackett, Mark J; George, Graham N; Kelly, Michael E

2018-05-16

Stroke exacts a heavy financial and economic burden, is a leading cause of death, and is the leading cause of long-term disability in those who survive. The penumbra surrounds the ischemic core of the stroke lesion and is composed of cells that are stressed and vulnerable to death, which is due to an altered metabolic, oxidative, and ionic environment within the penumbra. Without therapeutic intervention, many cells within the penumbra will die and become part of the growing infarct, however, there is hope that appropriate therapies may allow potential recovery of cells within this tissue region, or at least slow the rate of cell death, therefore, slowing the spread of the ischemic infarct and minimizing the extent of tissue damage. As such, preserving the penumbra to promote functional brain recovery is a central goal in stroke research. While identification of the ischemic infarct, and the infarct/penumbra boundary is relatively trivial using classical histology and microscopy techniques, accurately assessing the penetration of the penumbra zone into undamaged brain tissue, and evaluating the magnitude of chemical alterations in the penumbra, has long been a major challenge to the stroke research field. In this study, we have used synchrotron-based X-ray fluorescence imaging to visualize the elemental changes in undamaged, penumbra, and infarct brain tissue, following ischemic stroke. We have employed a Gaussian mixture model to cluster tissue areas based on their elemental characteristics. The method separates the core of the infarct from healthy tissue, and also demarcates discrete regions encircling the infarct. These regions of interest can be combined with elemental and metabolic data, as well as with conventional histology. The cell populations defined by clustering provide a reproducible means of visualizing the size and extent of the penumbra at the level of the single cell and provide a critically needed tool to track changes in elemental status and penumbra size.

Long-delayed bright dancing sprite with large Horizontal displacement from its parent flash

NASA Astrophysics Data System (ADS)

Yang, Jing; Lu, Gaopeng; Lee, Li-Jou; Feng, Guili

2015-07-01

We reported in this paper the observation of a very bright long-delayed dancing sprite with distinct horizontal displacement from its parent stroke. The dancing sprite lasted only 60 ms, and the morphology consisted of three fields with two slim dim sprite elements in the first two fields and a very bright large element in the third field, different from other observations where the dancing sprites usually contained multiple elements over a longer time interval, and the sprite shape and brightness in the video field are often similar to the previous fields. The bright sprite was displaced at least 38 km from its parent cloud-to-ground (CG) stroke and occurred over comparatively higher cloud top region. The parent flash of this compact dancing sprite was of positive polarity, with only one return stroke (approximately +24 kA) and obvious continuing current process, and the charge moment change of stroke was small (barely above the threshold for sprite production). All the sprite elements occurred during the continuing current stage, and the bright long-delayed sprite element induced a considerable current pulse. The dancing feature of this sprite may be linked to the electrical charge structure, dynamics and microphysics of parent storm, and the inferred development of parent CG flash was consistent with previous very high-frequency (VHF) observations of lightning in the same region.

The Utility of the Faces Pain Scale in the Assessment of Shoulder Pain in Turkish Stroke Patients: Its Relation with Quality of Life and Psychologic Status

ERIC Educational Resources Information Center

Dogan, Sebnem Koldas; Ay, Saime; Oztuna, Derya; Aytur, Yesim Kurtais; Evcik, Deniz

2010-01-01

This study was planned to investigate the utility of the vertical Faces Pain Scale (FPS) in the assessment of pain in stroke patients using the shoulder pain model and to assess its utility in the Turkish patient population. The secondary aim was to analyze the association of FPS with the quality of life and depression in the study population.…

Dignity realization of patients with stroke in hospital care: A grounded theory.

PubMed

Rannikko, Sunna; Stolt, Minna; Suhonen, Riitta; Leino-Kilpi, Helena

2017-01-01

Dignity is seen as an important but complex concept in the healthcare context. In this context, the discussion of dignity includes concepts of other ethical principles such as autonomy and privacy. Patients consider dignity to cover individuality, patient's feelings, communication, and the behavior of healthcare personnel. However, there is a lack of knowledge concerning the realization of patients' dignity in hospital care and the focus of the study is therefore on the realization of dignity of the vulnerable group of patients with stroke. The aim of the study was to create a theoretical construct to describe the dignity realization of patients with stroke in hospital care. Research design and participants: Patients with stroke (n = 16) were interviewed in 2015 using a semi-structured interview containing open questions concerning dignity. The data were analyzed using constant comparison of Grounded Theory. Ethical considerations: Ethical approval for the research was obtained from the Ethics Committee of the University. The permission for the research was given by the hospital. Informed consent was obtained from participants. The "Theory of Dignity Realization of Patients with Stroke in Hospital Care" consists of a core category including generic elements of the new situation and dignity realization types. The core category was identified as "Dignity in a new situation" and the generic elements as health history, life history, individuality and stroke. Dignity of patients with stroke is realized through specific types of realization: person-related dignity type, control-related dignity type, independence-related dignity type, social-related dignity type, and care-related dignity type. The theory has similar elements with the previous literature but the whole construct is new. The theory reveals possible special characteristics in dignity realization of patients with stroke. For healthcare personnel, the theory provides a frame for a better understanding and recognition of how dignity of patients with stroke is realized.

Do post-stroke patients benefit from robotic verticalization? A pilot-study focusing on a novel neurophysiological approach

PubMed Central

Calabrò, Rocco Salvatore; Naro, Antonino; Russo, Margherita; Leo, Antonino; Balletta, Tina; Saccá, Ileana; De Luca, Rosaria; Bramanti, Placido

2015-01-01

Abstract Background: Tilt-table equipped with the dynamic foot-support (ERIGO) and the functional electric stimulation could be a safe and suitable device for stabilization of vital signs, increasing patient’s motivation for further recovery, decreasing the duration of hospitalization, and accelerating the adaptation to vertical posture in bedridden patients with brain-injury. Moreover, it is conceivable that verticalization may improve cognitive functions, and induce plastic changes at sensory motor and vestibular system level that may in turn facilitate motor functional recovery. Objective: To test the safety and effectiveness of ERIGO treatment on motor and cognitive functions, cortical plasticity within vestibular and sensory-motor systems in a bedridden post-stroke sample. Methods: 20 patients were randomly divided in two groups that performed ERIGO training (30 sessions) (G1) or physiotherapist-assisted verticalization training (same duration) (G2), beyond conventional neurorehabilitation treatment. Motor and cognitive functions as well as sensory-motor and vestibular system plasticity were investigated either before (T0) or after (T1) the rehabilitative protocols. Results: Both the verticalization treatments were well-tolerated. Notably, the G1 patients had a significant improvement in cognitive function (p = 0.03), global motor function (p = 0.006), sensory-motor (p <  0.001) and vestibular system plasticity (p = 0.02) as compared to G2. Conclusions: ERIGO training could be a valuable tool for the adaptation to the vertical position with a better global function improvement, as also suggested by the sensory-motor and vestibular system plasticity induction. PMID:26410207

Physiological characterization of gravitaxis in Euglena gracilis and Astasia longa studied on sounding rocket flights.

PubMed

Richter, P R; Lebert, M; Tahedl, H; Hader, D P

2001-01-01

Euglena gracilis is a photosynthetic, unicellular flagellate found in eutrophic freshwater habitats. The organisms control their vertical position in the water column using gravi- and phototaxis. Recent experiments demonstrated that negative gravitaxis cannot be explained by passive buoyancy but by an active physiological mechanism. During space experiments, the threshold of gravitaxis was determined to be between 0.08 and 0.12 x g. A strong correlation between the applied acceleration and the intracellular cAMP and Ca2+ was observed. The results support the hypothesis, that the cell body of Euglena, which is denser than the surrounding medium exerts a pressure onto the lower membrane and activates mechanosensitive Ca2+ channels. Changes in the membrane potential and the cAMP concentration are most likely subsequent elements in a signal transduction chain, which results in reorientation strokes of the flagellum. c 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

One Stroke at a Time

ERIC Educational Resources Information Center

Hollibaugh, Molly

2012-01-01

At first glance, a Zentangle creation can seem intricate and complicated. But, when you learn how it is done, you realize how simple it is. Zentangles are patterns, or "tangles," that have been reduced to a simple sequence of elemental strokes. When you learn to focus on each stroke you find yourself capable of things that you may have once…

Analysis of Relationships between the Level of Errors in Leg and Monofin Movement and Stroke Parameters in Monofin Swimming

PubMed Central

Rejman, Marek

2013-01-01

The aim of this study was to analyze the error structure in propulsive movements with regard to its influence on monofin swimming speed. The random cycles performed by six swimmers were filmed during a progressive test (900m). An objective method to estimate errors committed in the area of angular displacement of the feet and monofin segments was employed. The parameters were compared with a previously described model. Mutual dependences between the level of errors, stroke frequency, stroke length and amplitude in relation to swimming velocity were analyzed. The results showed that proper foot movements and the avoidance of errors, arising at the distal part of the fin, ensure the progression of swimming speed. The individual stroke parameters distribution which consists of optimally increasing stroke frequency to the maximal possible level that enables the stabilization of stroke length leads to the minimization of errors. Identification of key elements in the stroke structure based on the analysis of errors committed should aid in improving monofin swimming technique. Key points The monofin swimming technique was evaluated through the prism of objectively defined errors committed by the swimmers. The dependences between the level of errors, stroke rate, stroke length and amplitude in relation to swimming velocity were analyzed. Optimally increasing stroke rate to the maximal possible level that enables the stabilization of stroke length leads to the minimization of errors. Propriety foot movement and the avoidance of errors arising at the distal part of fin, provide for the progression of swimming speed. The key elements improving monofin swimming technique, based on the analysis of errors committed, were designated. PMID:24149742

Electrically floating, near vertical incidence, skywave antenna

DOEpatents

Anderson, Allen A.; Kaser, Timothy G.; Tremblay, Paul A.; Mays, Belva L.

2014-07-08

An Electrically Floating, Near Vertical Incidence, Skywave (NVIS) Antenna comprising an antenna element, a floating ground element, and a grounding element. At least part of said floating ground element is positioned between said antenna element and said grounding element. The antenna is separated from the floating ground element and the grounding element by one or more electrical insulators. The floating ground element is separated from said antenna and said grounding element by one or more electrical insulators.

Periodontal biomechanics: finite element simulations of closing stroke and power stroke in equine cheek teeth

PubMed Central

2012-01-01

Background In equine dentistry periodontal diseases, especially periapical inflammation, are frequently occurring problems. Anachoresis is believed to be the most common cause for the development of such disorders. Nevertheless, there is still no substantiated explanation why settlement of pathogen microorganisms occurs in equine periodontal tissues. It is expected that excessive strains and stresses occurring in the periodontal ligament (PDL) during the horse’s chewing cycle might be a predisposing factor. In this study this assumption was examined by finite element (FE) analyses on virtual 3-D models of equine maxillary and mandibular cheek teeth, established on the basis of μCT datasets. Calculations were conducted both under conditions of closing and power stroke. Results Results showed a uniform distribution of low stresses and strain energy density (SED) during closing stroke, whereas during power stroke an occurrence of high stresses and SED could be observed in the PDL near the alveolar crest and in periapical regions. Conclusion The concentration of forces during power stroke in these specific areas of the PDL may cause local tissue necrosis and inflammation and thus establish a suitable environment for the settlement of microorganisms. PMID:22607543

Vertically reciprocating auger

NASA Technical Reports Server (NTRS)

Etheridge, Mark; Morgan, Scott; Fain, Robert; Pearson, Jonathan; Weldi, Kevin; Woodrough, Stephen B., Jr.

1988-01-01

The mathematical model and test results developed for the Vertically Reciprocating Auger (VRA) are summarized. The VRA is a device capable of transporting cuttings that result from below surface drilling. It was developed chiefly for the lunar surface, where conventional fluid flushing while drilling would not be practical. The VRA uses only reciprocating motion and transports material through reflections with the surface above. Particles are reflected forward and land ahead of radially placed fences, which prevent the particles from rolling back down the auger. Three input wave forms are considered to drive the auger. A modified sawtooth wave form was chosen for testing, over a modified square wave or sine wave, due to its simplicity and effectiveness. The three-dimensional mathematical model predicted a sand throughput rate of 0.2667 pounds/stroke, while the actual test setup transported 0.075 pounds/stroke. Based on this result, a correction factor of 0.281 is suggested for a modified sawtooth input.

Aerodynamic performance and particle image velocimetery of piezo actuated biomimetic manduca sexta engineered wings towards the design and application of a flapping wing flight vehicle

NASA Astrophysics Data System (ADS)

DeLuca, Anthony M.

Considerable research and investigation has been conducted on the aerodynamic performance, and the predominate flow physics of the Manduca Sexta size of biomimetically designed and fabricated wings as part of the AFIT FWMAV design project. Despite a burgeoning interest and research into the diverse field of flapping wing flight and biomimicry, the aerodynamics of flapping wing flight remains a nebulous field of science with considerable variance into the theoretical abstractions surrounding aerodynamic mechanisms responsible for aerial performance. Traditional FWMAV flight models assume a form of a quasi-steady approximation of wing aerodynamics based on an infinite wing blade element model (BEM). An accurate estimation of the lift, drag, and side force coefficients is a critical component of autonomous stability and control models. This research focused on two separate experimental avenues into the aerodynamics of AFIT's engineered hawkmoth wings|forces and flow visualization. 1. Six degree of freedom force balance testing, and high speed video analysis was conducted on 30°, 45°, and 60° angle stop wings. A novel, non-intrusive optical tracking algorithm was developed utilizing a combination of a Gaussian Mixture Model (GMM) and ComputerVision (OpenCV) tools to track the wing in motion from multiple cameras. A complete mapping of the wing's kinematic angles as a function of driving amplitude was performed. The stroke angle, elevation angle, and angle of attack were tabulated for all three wings at driving amplitudes ranging from A=0.3 to A=0.6. The wing kinematics together with the force balance data was used to develop several aerodynamic force coefficient models. A combined translational and rotational aerodynamic model predicted lift forces within 10%, and vertical forces within 6%. The total power consumption was calculated for each of the three wings, and a Figure of Merit was calculated for each wing as a general expression of the overall efficiency of the wing. Th 60° angle stop wing achieved the largest total stroke angle and generated the most lift for the lowest power consumption of the wings tested. 2. Phase averaged stereo Particle Image Velocimetry (PIV) data was collected at eight phases through the flap cycle on the 30°, 45°, and 60° angle stop wings. Wings were mounted transverse and parallel to the interrogating laser sheet, and planar velocity intersections at the wing mid-span, one chord below the wing, were compared to one another to verify data fidelity. A Rankine-Froude actuator disk model was adapted to calculate the approximate vertical thrust generated from the total momentum flux through the flapping semi-disk using the velocity field measurements. Three component stereo u, v, and w-velocity contour measurements confirmed the presence of extensive vortical structures in the vicinity of the wing. The leading edge vortex was successfully tracked through the stroke cycle appearing at approximately 25% span, increasing in circulatory strength and translational velocity down the span toward the tip, and dissipating just after 75% span. Thrust calculations showed the vertically mounted wing more accurately represented the vertical forces when compared to its corresponding force balance measurement than the horizontally mounted wing. The mid-span showed the highest vertical velocity profile below the wing; and hence, was the location responsible for the majority of lift production along the span.

Reactive Balance in Individuals With Chronic Stroke: Biomechanical Factors Related to Perturbation-Induced Backward Falling.

PubMed

Salot, Pooja; Patel, Prakruti; Bhatt, Tanvi

2016-03-01

An effective compensatory stepping response is the first line of defense for preventing a fall during sudden large external perturbations. The biomechanical factors that contribute to heightened fall risk in survivors of stroke, however, are not clearly understood. It is known that impending sensorimotor and balance deficits poststroke predispose these individuals to a risk of fall during sudden external perturbations. The purpose of this study was to examine the mechanism of fall risk in survivors of chronic stroke when exposed to sudden, slip-like forward perturbations in stance. This was a cross-sectional study. Fourteen individuals with stroke, 14 age-matched controls (AC group), and 14 young controls (YC group) were exposed to large-magnitude forward stance perturbations. Postural stability was computed as center of mass (COM) position (XCOM/BOS) and velocity (ẊCOM/BOS) relative to the base of support (BOS) at first step lift-off (LO) and touch-down (TD) and at second step TD. Limb support was quantified as vertical hip descent (Zhip) from baseline after perturbation onset. All participants showed a backward balance loss, with 71% of the stroke group experiencing a fall compared with no falls in the control groups (AC and YC groups). At first step LO, no between-group differences in XCOM/BOS and ẊCOM/BOS were noted. At first step TD, however, the stroke group had a significantly posterior XCOM/BOS and backward ẊCOM/BOS compared with the control groups. At second step TD, individuals with stroke were still more unstable (more posterior XCOM/BOS and backward ẊCOM/BOS) compared with the AC group. Individuals with stroke also showed greater peak Zhip compared with the control groups. Furthermore, the stroke group took a larger number of steps with shorter step length and delayed step initiation compared with the control groups. Although the study highlights the reactive balance deficits increasing fall risk in survivors of stroke compared with healthy adults, the study was restricted to individuals with chronic stroke only. It is likely that comparing compensatory stepping responses across different stages of recovery would enable clinicians to identify reactive balance deficits related to a specific stage of recovery. These findings suggest the inability of the survivors of stroke to regain postural stability with one or more compensatory steps, unlike their healthy counterparts. Such a response may expose them to a greater fall risk resulting from inefficient compensatory stepping and reduced vertical limb support. Therapeutic interventions for fall prevention, therefore, should focus on improving both reactive stepping and limb support. © 2016 American Physical Therapy Association.

Dynamic analysis of an SDOF helicopter model featuring skid landing gear and an MR damper by considering the rotor lift factor and a Bingham number

NASA Astrophysics Data System (ADS)

Saleh, Muftah; Sedaghati, Ramin; Bhat, Rama

2018-06-01

The present study addresses the performance of a skid landing gear (SLG) system of a rotorcraft impacting the ground at a vertical sink rate of up to 4.5 ms‑1. The impact attitude is assumed to be level as per chapter 527 of the Airworthiness Manual of Transport Canada Civil Aviation and part 27 of the Federal Aviation Regulations of the US Federal Aviation Administration. A single degree of freedom helicopter model is investigated under different values of rotor lift factor, L. In this study, three SLG versions are evaluated: (a) standalone conventional SLG; (b) SLG equipped with a passive viscous damper; and (c) SLG incorporated a magnetorheological energy absorber (MREA). The non-dimensional solutions of the helicopter models show that the two former SLG systems suffer adaptability issues with variations in the impact velocity and the rotor lift factor. Therefore, the alternative successful choice is to employ the MREA. Two different optimum Bingham numbers for compression and rebound strokes are defined. A new chart, called the optimum Bingham number versus rotor lift factor ‘B{i}o-L’, is introduced in this study to correlate the optimum Bingham numbers to the variation in the rotor lift factor and to provide more accessibility from the perspective of control design. The chart shows that the optimum Bingham number for the compression stroke is inversely linearly proportional to the increase in the rotor lift factor. This alleviates the impact force on the system and reduces the amount of magnetorheological yield force that would be generated. On the contrary, the optimum Bingham number for the rebound stroke is found to be directly linearly proportional to the rotor lift factor. This ensures controllable attenuation of the restoring force of the linear spring element. This idea can be exploited to generate charts for different landing attitudes and sink rates. In this article, the response of the helicopter equipped with the conventional undamped, damped, and MREA based SLG are numerically simulated using three sets of Bingham numbers. Namely, an underestimated, optimum, and overestimated Bingham number for every stroke. The simulation results depict that the only feasible solution is when the MREA generates the optimum damping force corresponding to the optimum Bingham numbers. Under this circumstance, the MREA utilizes the available energy absorption stroke to attain a soft landing. Furthermore, in the rebound stroke, the optimum damping force resettles the helicopter to its equilibrium position and prevents oscillations after the end of the rebound stroke.

Clap-and-fling mechanism in a hovering insect-like two-winged flapping-wing micro air vehicle.

PubMed

Phan, Hoang Vu; Au, Thi Kim Loan; Park, Hoon Cheol

2016-12-01

This study used numerical and experimental approaches to investigate the role played by the clap-and-fling mechanism in enhancing force generation in hovering insect-like two-winged flapping-wing micro air vehicle (FW-MAV). The flapping mechanism was designed to symmetrically flap wings at a high flapping amplitude of approximately 192°. The clap-and-fling mechanisms were thereby implemented at both dorsal and ventral stroke reversals. A computational fluid dynamic (CFD) model was constructed based on three-dimensional wing kinematics to estimate the force generation, which was validated by the measured forces using a 6-axis load cell. The computed forces proved that the CFD model provided reasonable estimation with differences less than 8%, when compared with the measured forces. The measurement indicated that the clap and flings at both the stroke reversals augmented the average vertical force by 16.2% when compared with the force without the clap-and-fling effect. In the CFD simulation, the clap and flings enhanced the vertical force by 11.5% and horizontal drag force by 18.4%. The observations indicated that both the fling and the clap contributed to the augmented vertical force by 62.6% and 37.4%, respectively, and to the augmented horizontal drag force by 71.7% and 28.3%, respectively. The flow structures suggested that a strong downwash was expelled from the opening gap between the trailing edges during the fling as well as the clap at each stroke reversal. In addition to the fling phases, the influx of air into the low-pressure region between the wings from the leading edges also significantly contributed to augmentation of the vertical force. The study conducted for high Reynolds numbers also confirmed that the effect of the clap and fling was insignificant when the minimum distance between the two wings exceeded 1.2c (c = wing chord). Thus, the clap and flings were successfully implemented in the FW-MAV, and there was a significant improvement in the vertical force.

Clap-and-fling mechanism in a hovering insect-like two-winged flapping-wing micro air vehicle

PubMed Central

Phan, Hoang Vu; Au, Thi Kim Loan

2016-01-01

This study used numerical and experimental approaches to investigate the role played by the clap-and-fling mechanism in enhancing force generation in hovering insect-like two-winged flapping-wing micro air vehicle (FW-MAV). The flapping mechanism was designed to symmetrically flap wings at a high flapping amplitude of approximately 192°. The clap-and-fling mechanisms were thereby implemented at both dorsal and ventral stroke reversals. A computational fluid dynamic (CFD) model was constructed based on three-dimensional wing kinematics to estimate the force generation, which was validated by the measured forces using a 6-axis load cell. The computed forces proved that the CFD model provided reasonable estimation with differences less than 8%, when compared with the measured forces. The measurement indicated that the clap and flings at both the stroke reversals augmented the average vertical force by 16.2% when compared with the force without the clap-and-fling effect. In the CFD simulation, the clap and flings enhanced the vertical force by 11.5% and horizontal drag force by 18.4%. The observations indicated that both the fling and the clap contributed to the augmented vertical force by 62.6% and 37.4%, respectively, and to the augmented horizontal drag force by 71.7% and 28.3%, respectively. The flow structures suggested that a strong downwash was expelled from the opening gap between the trailing edges during the fling as well as the clap at each stroke reversal. In addition to the fling phases, the influx of air into the low-pressure region between the wings from the leading edges also significantly contributed to augmentation of the vertical force. The study conducted for high Reynolds numbers also confirmed that the effect of the clap and fling was insignificant when the minimum distance between the two wings exceeded 1.2c (c = wing chord). Thus, the clap and flings were successfully implemented in the FW-MAV, and there was a significant improvement in the vertical force. PMID:28083112

Crash Testing and Simulation of a Cessna 172 Aircraft: Hard Landing Onto Concrete

NASA Technical Reports Server (NTRS)

Jackson, Karen E.; Fasanella, Edwin L.

2016-01-01

A full-scale crash test of a Cessna 172 aircraft was conducted at the Landing and Impact Research Facility at NASA Langley Research Center during the summer of 2015. The purpose of the test was to evaluate the performance of Emergency Locator Transmitters (ELTs) that were mounted at various locations in the aircraft and to generate impact test data for model validation. A finite element model of the aircraft was developed for execution in LSDYNA to simulate the test. Measured impact conditions were 722.4-in/s forward velocity and 276-in/s vertical velocity with a 1.5deg pitch (nose up) attitude. These conditions were intended to represent a survivable hard landing. The impact surface was concrete. During the test, the nose gear tire impacted the concrete, followed closely by impact of the main gear tires. The main landing gear spread outward, as the nose gear stroked vertically. The only fuselage contact with the impact surface was a slight impact of the rearmost portion of the lower tail. Thus, capturing the behavior of the nose and main landing gear was essential to accurately predict the response. This paper describes the model development and presents test-analysis comparisons in three categories: inertial properties, time sequence of events, and acceleration and velocity time-histories.

[Elements of system semiotics of the brain and head with cranial vessels of patients with stroke and with risk of stroke development].

PubMed

Makomela, N M

2007-01-01

By means of a multispiral computer and magnetic resonance tomography 211 patients with an ischemic stroke, 109 patients with hemorrhagic stroke, 41 patients with an arterial hypertensia, 43 patients with aneurism, 58 patients with discirculation encephalopathy, 125 patients with ischemic illness of heart, practically healthy 62 have been observed. The author found high frequency of pathological deformations of carotid and vertebral arteries of not closed arterial circle, calcification of the pineal body and vascular plexus of lateral ventricles. cysts of maxillary sinuses of patients with stroke in comparison with patients at risk of the development of stroke and practically healthy subjects.

Second-order processing of four-stroke apparent motion.

PubMed

Mather, G; Murdoch, L

1999-05-01

In four-stroke apparent motion displays, pattern elements oscillate between two adjacent positions and synchronously reverse in contrast, but appear to move unidirectionally. For example, if rightward shifts preserve contrast but leftward shifts reverse contrast, consistent rightward motion is seen. In conventional first-order displays, elements reverse in luminance contrast (e.g. light elements become dark, and vice-versa). The resulting perception can be explained by responses in elementary motion detectors turned to spatio-temporal orientation. Second-order motion displays contain texture-defined elements, and there is some evidence that they excite second-order motion detectors that extract spatio-temporal orientation following the application of a non-linear 'texture-grabbing' transform by the visual system. We generated a variety of second-order four-stroke displays, containing texture-contrast reversals instead of luminance contrast reversals, and used their effectiveness as a diagnostic test for the presence of various forms of non-linear transform in the second-order motion system. Displays containing only forward or only reversed phi motion sequences were also tested. Displays defined by variation in luminance, contrast, orientation, and size were effective. Displays defined by variation in motion, dynamism, and stereo were partially or wholly ineffective. Results obtained with contrast-reversing and four-stroke displays indicate that only relatively simple non-linear transforms (involving spatial filtering and rectification) are available during second-order energy-based motion analysis.

[Organization and methodology of early rehabilitation of the patients with cardioembolic stroke complicated by cardiac insufficiency].

PubMed

Isaeva, T V

2013-01-01

The present work was focused on the safety and effectiveness of the combined rehabilitative treatment in the case of pre-acute and acute cardioembolic stroke in 45 patients with varying degree of cardiac decompensation. The study showed that the use of "passive" remediation, such as the postural treatment, breathing exercises, selective massage, neuromuscular electrical stimulation, is safe and can be recommended to the patients with stroke and cardiac decompensation of different severity (II and III FC of chronic cardiac insufficiency). The introduction of such active measures as verticalization into the program of comprehensive rehabilitation may cause decompensation of cardiac insufficiency. The rehabilitation strategy used in the present study improved performance and exercise tolerance in the majority of the patients. Moreover, it resulted in the significant reduction of the severity of stroke, improved the motor function, and increased functional independence of the patients.

Investigating the tool marks on oracle bones inscriptions from the Yinxu site (ca., 1319-1046 BC), Henan province, China.

PubMed

Zhao, Xiaolong; Tang, Jigen; Gu, Zhou; Shi, Jilong; Yang, Yimin; Wang, Changsui

2016-09-01

Oracle Bone Inscriptions in the Shang dynasty (1600-1046 BC) are the earliest well-developed writing forms of the Chinese character system, and their carving techniques have not been studied by tool marks analysis with microscopy. In this study, a digital microscope with three-dimensional surface reconstruction based on extended depth of focus technology was used to investigate tool marks on the surface of four pieces of oracle bones excavated at the eastern area of Huayuanzhuang, Yinxu site(ca., 1319-1046 BC), the last capital of the Shang dynasty, Henan province, China. The results show that there were two procedures to carve the characters on the analyzed tortoise shells. The first procedure was direct carving. The second was "outlining design," which means to engrave a formal character after engraving a draft with a pointed tool. Most of the strokes developed by an engraver do not overlap the smaller draft, which implies that the outlining design would be a sound way to avoid errors such as wrong and missing characters. The strokes of these characters have different shape at two ends and variations on width and depth of the grooves. Moreover, the bottom of the grooves is always rugged. Thus, the use of rotary wheel-cutting tools could be ruled out. In most cases, the starting points of the strokes are round or flat while the finishing points are always pointed. Moreover, the strokes should be engraved from top to bottom. When vertical or horizontal strokes had been engraved, the shell would be turned about 90 degrees to engrave the crossed strokes from top to bottom. There was no preferred order to engrave vertical or horizontal strokes. Since both sides of the grooves of the characters are neat and there exists no unorganized tool marks, then it is suggested that some sharp tools had been used for engraving characters on the shells. Microsc. Res. Tech. 79:827-832, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Horizontal electric fields from lightning return strokes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomson, E.M.; Uman, M.A.; Johnson, J.

1985-01-01

Measurements are presented of simultaneous horizontal and vertical electric fields from both close and distant lightning return strokes. The data were obtained during summer 1984 at the Kennedy Space Center, Florida, using an electrically isolated spherical antenna having a system bandwidth of 3 Hz to 5 MHz. Lightning signals were obtained from flashes at distances from a few to 100 kilometers. Since the horizontal electric field is in part determined by the local ground conductivity, that parameter was measured as a function of depth. The horizontal fields from lightning return strokes had typically 1/50 the peak amplitude of the verticalmore » fields and waveshapes which were consistant with available theory, as expressed by the ''wavetilt'' formula.« less

VIEW OF PDP TANK TOP, LEVEL 0’, WITH VERTICAL ELEMENTS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF PDP TANK TOP, LEVEL 0’, WITH VERTICAL ELEMENTS IN BACKGROUND, LTR TANK TOP ON LEFT, AND SHEAVE RACK ELEMENTS AT TOP, LOOKING NORTH - Physics Assembly Laboratory, Area A/M, Savannah River Site, Aiken, Aiken County, SC

The Subjective Postural Vertical Determined in Patients with Pusher Behavior During Standing.

PubMed

Bergmann, Jeannine; Krewer, Carmen; Selge, Charlotte; Müller, Friedemann; Jahn, Klaus

2016-06-01

The subjective postural vertical (SPV), i.e., the perceived upright orientation of the body in relation to gravity, is disturbed in patients with pusher behavior. So far, the SPV has been measured only when these patients were sitting, and the results were contradictory as regards the side of the SPV deviation. The objective was to investigate the SPV in patients with different degrees of severity of pusher behavior while standing. Eight stroke patients with pusher behavior, ten age-matched stroke patients without pusher behavior, and ten age-matched healthy control subjects were included. The SPV (SPV error, SPV range) was assessed in the pitch and the roll planes. Pusher behavior was classified with the Burke Lateropulsion Scale (BLS). In the pitch plane, the SPV range was significantly larger in pusher patients than in patients without pusher behavior or healthy controls. The SPV error was similar for groups. In the roll plane, the SPV error and the SPV range were significantly larger and more ipsilesionally tilted in the pusher group than in the other two groups. There was a significant correlation between the SPV error in the roll plane and the BLS score. The study revealed that patients with pusher behavior had an ipsilesional SPV tilt that decreased with decreasing severity of the behavior. The large uncertainty in verticality estimation in both planes indicates that their sensitivity for the perception of verticality in space is generally disturbed. These findings emphasize the importance of specific rehabilitation approaches to recalibrate the impaired inner model of verticality.

Development of a Continuum Damage Mechanics Material Model of a Graphite-Kevlar(Registered Trademark) Hybrid Fabric for Simulating the Impact Response of Energy Absorbing Kevlar(Registered Trademark) Hybrid Fabric for Simulating the Impact Response of Energy Absorbing

NASA Technical Reports Server (NTRS)

Jackson, Karen E.; Fasanella, Edwin L.; Littell, Justin D.

2017-01-01

This paper describes the development of input properties for a continuum damage mechanics based material model, Mat 58, within LS-DYNA(Registered Trademark) to simulate the response of a graphite-Kevlar(Registered Trademark) hybrid plain weave fabric. A limited set of material characterization tests were performed on the hybrid graphite-Kevlar(Registered Trademark) fabric. Simple finite element models were executed in LS-DYNA(Registered Trademark) to simulate the material characterization tests and to verify the Mat 58 material model. Once verified, the Mat 58 model was used in finite element models of two composite energy absorbers: a conical-shaped design, designated the "conusoid," fabricated of four layers of hybrid graphite-Kevlar(Registered Trademark) fabric; and, a sinusoidal-shaped foam sandwich design, designated the "sinusoid," fabricated of the same hybrid fabric face sheets with a foam core. Dynamic crush tests were performed on components of the two energy absorbers, which were designed to limit average vertical accelerations to 25- to 40-g, to minimize peak crush loads, and to generate relatively long crush stroke values under dynamic loading conditions. Finite element models of the two energy absorbers utilized the Mat 58 model that had been verified through material characterization testing. Excellent predictions of the dynamic crushing response were obtained.

Hovering and targeting flight simulations of a dragonfly-like flapping wing-body model by the immersed boundary-lattice Boltzmann method

NASA Astrophysics Data System (ADS)

Hirohashi, Kensuke; Inamuro, Takaji

2017-08-01

Hovering and targeting flights of the dragonfly-like flapping wing-body model are numerically investigated by using the immersed boundary-lattice Boltzmann method. The governing parameters of the problem are the Reynolds number Re, the Froude number Fr, and the non-dimensional mass m. We set the parameters at Re = 200, Fr = 15 and m = 51. First, we simulate free flights of the model for various values of the phase difference angle ϕ between the forewing and the hindwing motions and for various values of the stroke angle β between the stroke plane and the horizontal plane. We find that the vertical motion of the model depends on the phase difference angle ϕ, and the horizontal motion of the model depends on the stroke angle β. Secondly, using the above results we try to simulate the hovering flight by dynamically changing the phase difference angle ϕ and the stroke angle β. The hovering flight can be successfully simulated by a simple proportional controller of the phase difference angle and the stroke angle. Finally, we simulate a targeting flight by dynamically changing the stroke angle β.

Can stroke patients use visual analogue scales?

PubMed

Price, C I; Curless, R H; Rodgers, H

1999-07-01

Visual analogue scales (VAS) have been used for the subjective measurement of mood, pain, and health status after stroke. In this study we investigated how stroke-related impairments could alter the ability of subjects to answer accurately. Consent was obtained from 96 subjects with a clinical stroke (mean age, 72.5 years; 50 men) and 48 control subjects without cerebrovascular disease (mean age, 71.5 years; 29 men). Patients with reduced conscious level or severe dysphasia were excluded. Subjects were asked to rate the tightness that they could feel on the (unaffected) upper arm after 3 low-pressure inflations with a standard sphygmomanometer cuff, which followed a predetermined sequence (20 mm Hg, 40 mm Hg, 0 mm Hg). Immediately after each change, they rated the perceived tightness on 5 scales presented in a random order: 4-point rating scale (none, mild, moderate, severe), 0 to 10 numerical rating scale, mechanical VAS, horizontal VAS, and vertical VAS. Standard tests recorded deficits in language, cognition, and visuospatial awareness. Inability to complete scales with the correct pattern was associated with any stroke (P<0.001). There was a significant association between success using scales and milder clinical stroke subtype (P<0.01). Within the stroke group, logistic regression analysis identified significant associations (P<0.05) between impairments (cognitive and visuospatial) and inability to complete individual scales correctly. Many patients after a stroke are unable to successfully complete self-report measurement scales, including VAS.

Toilet Grab-Bar Preference and Center of Pressure Deviation During Toilet Transfers in Healthy Seniors, Seniors With Hip Replacements, and Seniors Having Suffered a Stroke.

PubMed

Kennedy, Matthew Joel; Arcelus, Amaya; Guitard, Paulette; Goubran, R A; Sveistrup, Heidi

2015-01-01

Multiple toilet grab-bar configurations are required by people with a diverse spectrum of disability. The study purpose was to determine toilet grab-bar preference of healthy seniors, seniors with a hip replacement, and seniors post-stroke, and to determine the effect of each configuration on centre of pressure (COP) displacement during toilet transfers. 14 healthy seniors, 7 ambulatory seniors with a hip replacement, and 8 ambulatory seniors post-stroke participated in the study. Toilet transfers were performed with no bars (NB), commode (C), two vertical bars (2VB), one vertical bar (1VB), a horizontal bar (H), two swing-away bars (S) and a diagonal bar (D). COP was measured using pressure sensitive floor mats. Participants rated the safety, ease of use, helpfulness, comfort and preference for instalment. 2VB was most preferred and had the smallest COP deviation. Least preferred was H and NB. C caused largest COP displacement but had favourable ratings. The preference and safety of the 2VB should be considered in the design of accessible toilets and in accessibility construction guidelines. However these results need to be verified in non-ambulatory populations. C is frequently prescribed, but generates large COP deviation, suggesting it may present an increased risk of falls.

Dexamethasone-Loaded, PEGylated, Vertically Aligned, Multiwalled Carbon Nanotubes for Potential Ischemic Stroke Intervention.

PubMed

Komane, Patrick P; Kumar, Pradeep; Marimuthu, Thashree; Toit, Lisa C du; Kondiah, Pierre P D; Choonara, Yahya E; Pillay, Viness

2018-06-10

The complete synthesis, optimization, purification, functionalization and evaluation of vertically aligned multiwalled carbon nanotubes (VA-MWCNTs) was reported for potential application in dexamethasone delivery to the ischemic brain tissue. The conditions for high yield were optimized and carbon nanotubes functionalized and PEGylated prior to dexamethasone loading. Morphological changes were confirmed by SEM and TEM. Addition of functional groups to MWCNTs was demonstrated by FTIR. Thermal stability reduced following MWCNTs functionalization as demonstrated in TGA. The presence of carbon at 2θ of 25° and iron at 2θ of 45° in MWCNTs was illustrated by XRD. Polydispersive index and zeta potential were found to be 0.261 and −15.0 mV, respectively. Dexamethasone release increased by 55%, 65% and 95% in pH of 7.4, 6.5 and 5.5 respectively as evaluated by UV-VIS. The functionalized VA-MWCNTs were demonstrated to be less toxic in PC-12 cells in the concentration range from 20 to 20,000 µg/mL. These findings have demonstrated the potential of VA-MWCNTs in the enhancement of fast and prolonged release of dexamethasone which could lead to the effective treatment of ischemic stroke. More work is under way for targeting ischemic sites using atrial natriuretic peptide antibody in stroke rats.

The cloud-ionosphere discharge: a newly observed thunderstorm phenomenon.

PubMed

Winckler, J R

1997-09-30

This paper deals with a luminous electric discharge that forms in the mesospheric region between thundercloud tops and the ionosphere at 90-km altitude. These cloud-ionosphere discharges (CIs), following visual reports dating back to the 19th century, were finally imaged by a low-light TV camera as part of the "SKYFLASH" program at the University of Minnesota in 1989. Many observations were made by various groups in the period 1993-1996. The characteristics of CIs are that they have a wide range of sizes from a few kilometers up to 50 km horizontally; they extend from 40 km to nearly 90 km vertically, with an intense region near 60-70 km and streamers extending down toward cloud tops; the CIs are partly or entirely composed of vertical luminous filaments of kilometer size. The predominate color is red. The TV images show that the CIs usually have a duration less than one TV field (16.7 ms), but higher-speed photometric measurements show that they last about 3 ms, and are delayed 3 ms after an initiating cloud-ground lightning stroke; 95% of these initiating strokes are found to be "positive"-i.e., carry positive charges from clouds to ground. The preference for positive initiating strokes is not understood. Theories of the formation of CIs are briefly reviewed.

Road sign recognition during computer testing versus driving simulator performance for stroke and stroke+aphasia groups.

DOT National Transportation Integrated Search

2015-07-01

Driving is essential to maintaining independence. For most Americans preserving personal mobility is a : key element to retaining jobs, friends, activities and the basic necessities to maintain a household. This : is particularly true for older peopl...

The Standardization of the Clock Drawing Test (CDT) for People with Stroke Using Rasch Analysis

PubMed Central

Yoo, Doo Han; Hong, Deok Gi; Lee, Jae Shin

2014-01-01

[Purpose] The aim of this study was to standardize the clock drawing test (CDT) for people with stroke using Rasch analysis. [Subjects and Methods] Seventeen items of the CDT identified through a literature review were performed by 159 stroke patients. The data was analyzed with Winstep version 3.57 using the Rasch model to examine the unidimensionality of the items’ fit, the distribution of the items’ difficulty, and the reliability and appropriateness of the rating scale. [Result] Ten out of the 159 participations (6.2%) were considered misfit subjects, and one item of the CDT was determined to be a misfit item based on Rasch analysis. The rating scales were judged as suitable because the observed average showed an array of vertical orders and MNSQ values < 2. The separate index and reliability of the subject (1.98, 0.80) and item (6.45, 0.97) showed relatively high values. [Conclusion] This study is the first to examine the CDT scale in stroke patients by Rasch analysis. The CDT is expected to be useful for screening stroke patients with cognitive problems. PMID:24409026

Portable tomographic PIV measurements of swimming shelled Antarctic pteropods

NASA Astrophysics Data System (ADS)

Adhikari, Deepak; Webster, Donald R.; Yen, Jeannette

2016-12-01

A portable tomographic particle image velocimetry (tomographic PIV) system is described. The system was successfully deployed in Antarctica to study shelled Antarctic pteropods ( Limacina helicina antarctica)—a delicate organism with an unusual propulsion mechanism. The experimental setup consists of a free-standing frame assembled with optical rails, thus avoiding the need for heavy and bulky equipment (e.g. an optical table). The cameras, lasers, optics, and tanks are all rigidly supported within the frame assembly. The results indicate that the pteropods flap their parapodia (or "wings") downward during both power and recovery strokes, which is facilitated by the pitching of their shell. Shell pitching significantly alters the flapping trajectory, allowing the pteropod to move vertically and/or horizontally. The pronation and supination of the parapodia, together with the figure-eight motion during flapping, suggest similarities with insect flight. The volumetric velocity field surrounding the freely swimming pteropod reveals the generation of an attached vortex ring connecting the leading-edge vortex to the trailing-edge vortex during power stroke and a presence of a leading-edge vortex during recovery stroke. These vortex structures play a major role in accelerating the organism vertically and indicate that forces generated on the parapodia during flapping constitute both lift and drag. After completing each stroke, two vortex rings are shed into the wake of the pteropod. The complex combination of body kinematics (parapodia flapping, shell pitch, sawtooth trajectory), flow structures, and resulting force balance may be significantly altered by thinning of the pteropod shell, thus making pteropods an indicator of the detrimental effects of ocean acidification.

Study of Stroke Incidence in the Aseer Region, Southwestern Saudi Arabia.

PubMed

Alhazzani, Adel A; Mahfouz, Ahmed A; Abolyazid, Ahmed Y; Awadalla, Nabil J; Aftab, Razia; Faraheen, Aesha; Khalil, Shamsun Nahar

2018-01-26

Recent data regarding first-stroke incidence in Saudi Arabia in general and in the Aseer region in particular are scarce and even lacking. The aim of this work was to study the first-time stroke incidence in the Aseer region, southwestern Saudi Arabia. All first-stroke patients admitted to all hospitals in the Aseer region over a one-year period (January through December 2016) were included. Stroke patients outside the Aseer region were excluded from the study. The incidence per 100,000 patients and the concomitant 95% CI (Confidence Intervals) were computed. The present study included 1249 first-time stroke patients and calculated an overall minimal incidence rate of hospitalized first-time stroke of 57.64 per 100,000 persons per year (95% CI: 57.57-57.70). A steady increase was noticed depending on the patients' age, reaching a figure of 851.81 (95% CI: 849.2-854.5) for those patients aged 70 years and more. Overall, the incidence rate for females (48.14; 95% CI: 48.04-48.24) was lower compared to males (65.52; 95% CI: 65.1-66.0). Taking into consideration the expected rise of the elderly because of the prominent medical services provided by the Saudi government, leading to a subsequent change in the horizontal and vertical age distribution structure of the population, an increase in the number of stroke patients is expected. It is suggested to establish a nationwide stroke surveillance system in the Kingdom, with the objective to report, analyze, and maintain an updated overview of the stroke status in Saudi Arabia.

Verification of a non-hydrostatic dynamical core using horizontally spectral element vertically finite difference method: 2-D aspects

NASA Astrophysics Data System (ADS)

Choi, S.-J.; Giraldo, F. X.; Kim, J.; Shin, S.

2014-06-01

The non-hydrostatic (NH) compressible Euler equations of dry atmosphere are solved in a simplified two dimensional (2-D) slice framework employing a spectral element method (SEM) for the horizontal discretization and a finite difference method (FDM) for the vertical discretization. The SEM uses high-order nodal basis functions associated with Lagrange polynomials based on Gauss-Lobatto-Legendre (GLL) quadrature points. The FDM employs a third-order upwind biased scheme for the vertical flux terms and a centered finite difference scheme for the vertical derivative terms and quadrature. The Euler equations used here are in a flux form based on the hydrostatic pressure vertical coordinate, which are the same as those used in the Weather Research and Forecasting (WRF) model, but a hybrid sigma-pressure vertical coordinate is implemented in this model. We verified the model by conducting widely used standard benchmark tests: the inertia-gravity wave, rising thermal bubble, density current wave, and linear hydrostatic mountain wave. The results from those tests demonstrate that the horizontally spectral element vertically finite difference model is accurate and robust. By using the 2-D slice model, we effectively show that the combined spatial discretization method of the spectral element and finite difference method in the horizontal and vertical directions, respectively, offers a viable method for the development of a NH dynamical core.

Spontaneous Emergence of Legibility in Writing Systems: The Case of Orientation Anisotropy.

PubMed

Morin, Olivier

2018-03-01

Cultural forms are constrained by cognitive biases, and writing is thought to have evolved to fit basic visual preferences, but little is known about the history and mechanisms of that evolution. Cognitive constraints have been documented for the topology of script features, but not for their orientation. Orientation anisotropy in human vision, as revealed by the oblique effect, suggests that cardinal (vertical and horizontal) orientations, being easier to process, should be overrepresented in letters. As this study of 116 scripts shows, the orientation of strokes inside written characters massively favors cardinal directions, and it is organized in such a way as to make letter recognition easier: Cardinal and oblique strokes tend not to mix, and mirror symmetry is anisotropic, favoring vertical over horizontal symmetry. Phylogenetic analyses and recently invented scripts show that cultural evolution over the last three millennia cannot be the sole cause of these effects. Copyright © 2017 The Authors. Cognitive Science published by Wiley Periodicals, Inc. on behalf of Cognitive Science Society.

Sensitivity and Specificity of an Adult Stroke Screening Tool in Childhood Ischemic Stroke.

PubMed

Neville, Kerri; Lo, Warren

2016-05-01

There are frequent delays in the diagnosis of acute pediatric ischemic stroke. A screening tool that could increase the suspicion of acute ischemic stroke could aid early recognition and might improve initial care. An earlier study reported that children with acute ischemic stroke have signs that can be recognized with two adult stroke scales. We tested the hypothesis that an adult stroke scale could distinguish children with acute ischemic stroke from children with acute focal neurological deficits not due to stroke. We retrospectively applied an adult stroke scale to the recorded examinations of 53 children with acute symptomatic acute ischemic stroke and 53 age-matched control subjects who presented with focal neurological deficits. We examined the sensitivity and specificity of the stroke scale and the occurrence of acute seizures as predictors of stroke status. The total stroke scale did not differentiate children with acute ischemic stroke from those who had acute deficits from nonstroke causes; however, the presence of arm weakness was significantly associated with stroke cases. Acute seizures were significantly associated with stroke cases. An adult stroke scale is not sensitive or specific to distinguish children with acute ischemic stroke from those with nonstroke focal neurological deficits. The development of a pediatric acute ischemic stroke screening tool should include arm weakness and perhaps acute seizures as core elements. Such a scale must account for the limitations of language in young or intellectually disabled children. Copyright © 2016 Elsevier Inc. All rights reserved.

Analysis of spontaneous oscillations for a three-state power-stroke model.

PubMed

Washio, Takumi; Hisada, Toshiaki; Shintani, Seine A; Higuchi, Hideo

2017-02-01

Our study considers the mechanism of the spontaneous oscillations of molecular motors that are driven by the power stroke principle by applying linear stability analysis around the stationary solution. By representing the coupling equation of microscopic molecular motor dynamics and mesoscopic sarcomeric dynamics by a rank-1 updated matrix system, we derived the analytical representations of the eigenmodes of the Jacobian matrix that cause the oscillation. Based on these analytical representations, we successfully derived the essential conditions for the oscillation in terms of the rate constants of the power stroke and the reversal stroke transitions of the molecular motor. Unlike the two-state model, in which the dependence of the detachment rates on the motor coordinates or the applied forces on the motors plays a key role for the oscillation, our three-state power stroke model demonstrates that the dependence of the rate constants of the power and reversal strokes on the strains in the elastic elements in the motor molecules plays a key role, where these rate constants are rationally determined from the free energy available for the power stroke, the stiffness of the elastic element in the molecular motor, and the working stroke size. By applying the experimentally confirmed values to the free energy, the stiffness, and the working stroke size, our numerical model reproduces well the experimentally observed oscillatory behavior. Furthermore, our analysis shows that two eigenmodes with real positive eigenvalues characterize the oscillatory behavior, where the eigenmode with the larger eigenvalue indicates the transient of the system of the quick sarcomeric lengthening induced by the collective reversal strokes, and the smaller eigenvalue correlates with the speed of sarcomeric shortening, which is much slower than lengthening. Applying the perturbation analyses with primal physical parameters, we find that these two real eigenvalues occur on two branches derived from a merge point of a pair of complex-conjugate eigenvalues generated by Hopf bifurcation.

Landing Energy Dissipation for Manned Reentry Vehicles

NASA Technical Reports Server (NTRS)

Fisher, Lloyd J., Jr.

1960-01-01

Analytical and experimental investigations have been made to determine the landing-energy-dissipation characteristics for several types of landing gear for manned reentry vehicles. The landing vehicles are considered in two categories: those having essentially vertical-descent paths, the parachute-supported vehicles, and those having essentially horizontal paths, the lifting vehicles. The energy-dissipation devices discussed are crushable materials such as foamed plastics and honeycomb for internal application in couch-support systems, yielding metal elements as part of the structure of capsules or as alternates for oleos in landing-gear struts, inflatable bags, braking rockets, and shaped surfaces for water impact. It appears feasible to readily evaluate landing-gear systems for internal or external application in hard-surface or water landings by using computational procedures and free-body landing techniques with dynamic models. The systems investigated have shown very interesting energy-dissipation characteristics over a considerable range of landing parameters. Acceptable gear can be developed along lines similar to those presented if stroke requirements and human-tolerance limits are considered.

Evaluation of Lightning Incidence to Elements of a Complex Structure: A Monte Carlo Approach

NASA Technical Reports Server (NTRS)

Mata, Carlos T.; Rakov, V. A.

2008-01-01

There are complex structures for which the installation and positioning of the lightning protection system (LPS) cannot be done using the lightning protection standard guidelines. As a result, there are some "unprotected" or "exposed" areas. In an effort to quantify the lightning threat to these areas, a Monte Carlo statistical tool has been developed. This statistical tool uses two random number generators: a uniform distribution to generate origins of downward propagating leaders and a lognormal distribution to generate returns stroke peak currents. Downward leaders propagate vertically downward and their striking distances are defined by the polarity and peak current. Following the electrogeometrical concept, we assume that the leader attaches to the closest object within its striking distance. The statistical analysis is run for 10,000 years with an assumed ground flash density and peak current distributions, and the output of the program is the probability of direct attachment to objects of interest with its corresponding peak current distribution.

Evaluation of Lightning Incidence to Elements of a Complex Structure: A Monte Carlo Approach

NASA Technical Reports Server (NTRS)

Mata, Carlos T.; Rakov, V. A.

2008-01-01

There are complex structures for which the installation and positioning of the lightning protection system (LPS) cannot be done using the lightning protection standard guidelines. As a result, there are some "unprotected" or "exposed" areas. In an effort to quantify the lightning threat to these areas, a Monte Carlo statistical tool has been developed. This statistical tool uses two random number generators: a uniform distribution to generate the origin of downward propagating leaders and a lognormal distribution to generate the corresponding returns stroke peak currents. Downward leaders propagate vertically downward and their striking distances are defined by the polarity and peak current. Following the electrogeometrical concept, we assume that the leader attaches to the closest object within its striking distance. The statistical analysis is run for N number of years with an assumed ground flash density and the output of the program is the probability of direct attachment to objects of interest with its corresponding peak current distribution.

A variant of WEBINO syndrome after top of the basilar artery stroke.

PubMed

Sierra-Hidalgo, Fernando; Moreno-Ramos, Teresa; Villarejo, Alberto; Martín-Gil, Leticia; de Pablo-Fernández, Eduardo; Correas-Callero, Elisa; Ramos, Ana; Benito-León, Julián

2010-11-01

Wall-eyed bilateral internuclear ophthalmoplegia (WEBINO) is an uncommon neuro-ophthalmologic syndrome consisting of both eyes primary position exotropia and bilateral internuclear ophthalmoplegia. It is thought to be caused by medial midbrain lesions involving both bilateral medial longitudinal fasciculi and medial rectus subnuclei. We report the clinical and neuroimaging findings of a WEBINO syndrome associated to bilateral ptosis, non-reactive mydriasis and complete vertical gaze palsy in a 55-year-old man who suffered a top of the basilar artery stroke causing tegmental midbrain infarction. Copyright © 2010 Elsevier B.V. All rights reserved.

Multi-photon vertical cross-sectional imaging with a dynamically-balanced thin-film PZT z-axis microactuator.

PubMed

Choi, Jongsoo; Duan, Xiyu; Li, Haijun; Wang, Thomas D; Oldham, Kenn R

2017-10-01

Use of a thin-film piezoelectric microactuator for axial scanning during multi-photon vertical cross-sectional imaging is described. The actuator uses thin-film lead-zirconate-titanate (PZT) to generate upward displacement of a central mirror platform, micro-machined from a silicon-on-insulator (SOI) wafer to dimensions compatible with endoscopic imaging instruments. Device modeling in this paper focuses on existence of frequencies near device resonance producing vertical motion with minimal off-axis tilt even in the presence of multiple vibration modes and non-uniformity in fabrication outcomes. Operation near rear resonance permits large stroke lengths at low voltages relative to other vertical microactuators. Highly uniform vertical motion of the mirror platform is a key requirement for vertical cross-sectional imaging in the remote scan architecture being used for multi-photon instrument prototyping. The stage is installed in a benchtop testbed in combination with an electrostatic mirror that performs in-plane scanning. Vertical sectional images are acquired from 15 μm diameter beads and excised mouse colon tissue.

Sprite climatology in the Eastern Mediterranean Region

NASA Astrophysics Data System (ADS)

Yair, Yoav; Price, Colin; Katzenelson, Dor; Rosenthal, Neta; Rubanenko, Lior; Ben-Ami, Yuval; Arnone, Enrico

2015-04-01

We present statistical analysis of 436 sprites observed in 7 winter campaigns from 2006/7-2012/13. Results show a clear peak in the frequency of sprite detections, with maximum values (< 40% of events) between 00:30 and 02:15 LST (22:30-00:15 UT; LST = UT + 2). The detection times of sprites are well-correlated with a relative increase in the fraction of + CG strokes, which exhibit maxima between 00:00 and 02:00 LST. The morphological distribution of 339 sprites, that we were able to clearly identify, is dominated by column sprites (49.3%), with angels (33.0%) and carrots (25.7%) being less frequent. This is similar to reports of winter sprites over the Sea of Japan and summer ones in Central Europe. Other shapes such as trees, wishbones, etc. appear quite rarely. Single element events constitute 16.5% of observations, with 83.5% containing 2 elements or more. Clusters of homogenous types are slightly more frequent than mixed ones (55%). Our observations suggest winter Mediterranean thunderstorms to have a vertical structure in between high tropical convective systems and the lower cloud-top cells in Japan. The climatology shows the Eastern Mediterranean to be a major sprite producer in Northern Hemisphere winter, and offers ground-based coverage for future space missions.

HINTS to diagnose stroke in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging.

PubMed

Kattah, Jorge C; Talkad, Arun V; Wang, David Z; Hsieh, Yu-Hsiang; Newman-Toker, David E

2009-11-01

Acute vestibular syndrome (AVS) is often due to vestibular neuritis but can result from vertebrobasilar strokes. Misdiagnosis of posterior fossa infarcts in emergency care settings is frequent. Bedside oculomotor findings may reliably identify stroke in AVS, but prospective studies have been lacking. The authors conducted a prospective, cross-sectional study at an academic hospital. Consecutive patients with AVS (vertigo, nystagmus, nausea/vomiting, head-motion intolerance, unsteady gait) with >or=1 stroke risk factor underwent structured examination, including horizontal head impulse test of vestibulo-ocular reflex function, observation of nystagmus in different gaze positions, and prism cross-cover test of ocular alignment. All underwent neuroimaging and admission (generally <72 hours after symptom onset). Strokes were diagnosed by MRI or CT. Peripheral lesions were diagnosed by normal MRI and clinical follow-up. One hundred one high-risk patients with AVS included 25 peripheral and 76 central lesions (69 ischemic strokes, 4 hemorrhages, 3 other). The presence of normal horizontal head impulse test, direction-changing nystagmus in eccentric gaze, or skew deviation (vertical ocular misalignment) was 100% sensitive and 96% specific for stroke. Skew was present in 17% and associated with brainstem lesions (4% peripheral, 4% pure cerebellar, 30% brainstem involvement; chi(2), P=0.003). Skew correctly predicted lateral pontine stroke in 2 of 3 cases in which an abnormal horizontal head impulse test erroneously suggested peripheral localization. Initial MRI diffusion-weighted imaging was falsely negative in 12% (all <48 hours after symptom onset). Skew predicts brainstem involvement in AVS and can identify stroke when an abnormal horizontal head impulse test falsely suggests a peripheral lesion. A 3-step bedside oculomotor examination (HINTS: Head-Impulse-Nystagmus-Test-of-Skew) appears more sensitive for stroke than early MRI in AVS.

A fully consistent and conservative vertically adaptive coordinate system for SLIM 3D v0.4 with an application to the thermocline oscillations of Lake Tanganyika

NASA Astrophysics Data System (ADS)

Delandmeter, Philippe; Lambrechts, Jonathan; Legat, Vincent; Vallaeys, Valentin; Naithani, Jaya; Thiery, Wim; Remacle, Jean-François; Deleersnijder, Eric

2018-03-01

The discontinuous Galerkin (DG) finite element method is well suited for the modelling, with a relatively small number of elements, of three-dimensional flows exhibiting strong velocity or density gradients. Its performance can be highly enhanced by having recourse to r-adaptivity. Here, a vertical adaptive mesh method is developed for DG finite elements. This method, originally designed for finite difference schemes, is based on the vertical diffusion of the mesh nodes, with the diffusivity controlled by the density jumps at the mesh element interfaces. The mesh vertical movement is determined by means of a conservative arbitrary Lagrangian-Eulerian (ALE) formulation. Though conservativity is naturally achieved, tracer consistency is obtained by a suitable construction of the mesh vertical velocity field, which is defined in such a way that it is fully compatible with the tracer and continuity equations at a discrete level. The vertically adaptive mesh approach is implemented in the three-dimensional version of the geophysical and environmental flow Second-generation Louvain-la-Neuve Ice-ocean Model (SLIM 3D; www.climate.be/slim). Idealised benchmarks, aimed at simulating the oscillations of a sharp thermocline, are dealt with. Then, the relevance of the vertical adaptivity technique is assessed by simulating thermocline oscillations of Lake Tanganyika. The results are compared to measured vertical profiles of temperature, showing similar stratification and outcropping events.

Artistic Skills Recovery and Compensation in Visual Artists after Stroke.

PubMed

Petcu, Eugen Bogdan; Sherwood, Katherine; Popa-Wagner, Aurel; Buga, Ana Maria; Aceti, Lanfranco; Miroiu, Rodica Ileana

2016-01-01

Art is a characteristic of mankind, which requires superior central nervous processing and integration of motor functions with visual information. At the present time, a significant amount of information related to neurobiological basis of artistic creation has been derived from neuro-radiological cognitive studies, which have revealed that subsequent to tissue destruction, the artists continue to create art. The current study aims to review the most important cases of visual artists with stroke and to discuss artistic skills recovery and compensation as well as artistic style after stroke. The role of various central nervous system regions in artistic creation was reviewed on the basis of previously published functional studies. Our PubMed search (1995-2015) has identified 10 famous artists with right cerebral stroke as well as 5 with left cerebral stroke who survived and continued to create art after stroke. As the artists included in this review lived at various times during the twentieth century and in different countries, clinical information related to their case was limited. However, it appears that artistic skills recovery and compensation appear within days after stroke. Some of the artists would subsequently change their artistic style. All these elements have been evaluated within the context of specific clinical cases. The poststroke artistic skills recovery and compensation with development of a new style or the opposite, regaining the previous prestroke style, represents a significant element of clinical importance in medical rehabilitation as well as neuroesthetics, which requires further evaluation. At the present time, the molecular mechanisms of artistic creation are poorly understood, and more standardized clinical and experimental studies are needed.

Emergency Physician Attitudes, Preferences, and Risk Tolerance for Stroke as a Potential Cause of Dizziness Symptoms.

PubMed

Kene, Mamata V; Ballard, Dustin W; Vinson, David R; Rauchwerger, Adina S; Iskin, Hilary R; Kim, Anthony S

2015-09-01

We evaluated emergency physicians' (EP) current perceptions, practice, and attitudes towards evaluating stroke as a cause of dizziness among emergency department patients. We administered a survey to all EPs in a large integrated healthcare delivery system. The survey included clinical vignettes, perceived utility of historical and exam elements, attitudes about the value of and requisite post-test probability of a clinical prediction rule for dizziness. We calculated descriptive statistics and post-test probabilities for such a clinical prediction rule. The response rate was 68% (366/535). Respondents' median practice tenure was eight years (37% female, 92% emergency medicine board certified). Symptom quality and typical vascular risk factors increased suspicion for stroke as a cause of dizziness. Most respondents reported obtaining head computed tomography (CT) (74%). Nearly all respondents used and felt confident using cranial nerve and limb strength testing. A substantial minority of EPs used the Epley maneuver (49%) and HINTS (head-thrust test, gaze-evoked nystagmus, and skew deviation) testing (30%); however, few EPs reported confidence in these tests' bedside application (35% and 16%, respectively). Respondents favorably viewed applying a properly validated clinical prediction rule for assessment of immediate and 30-day stroke risk, but indicated it would have to reduce stroke risk to <0.5% to be clinically useful. EPs report relying on symptom quality, vascular risk factors, simple physical exam elements, and head CT to diagnose stroke as the cause of dizziness, but would find a validated clinical prediction rule for dizziness helpful. A clinical prediction rule would have to achieve a 0.5% post-test stroke probability for acceptability.

The cloud–ionosphere discharge: A newly observed thunderstorm phenomenon

PubMed Central

Winckler, John R.

1997-01-01

This paper deals with a luminous electric discharge that forms in the mesospheric region between thundercloud tops and the ionosphere at 90-km altitude. These cloud–ionosphere discharges (CIs), following visual reports dating back to the 19th century, were finally imaged by a low-light TV camera as part of the “SKYFLASH” program at the University of Minnesota in 1989. Many observations were made by various groups in the period 1993–1996. The characteristics of CIs are that they have a wide range of sizes from a few kilometers up to 50 km horizontally; they extend from 40 km to nearly 90 km vertically, with an intense region near 60–70 km and streamers extending down toward cloud tops; the CIs are partly or entirely composed of vertical luminous filaments of kilometer size. The predominate color is red. The TV images show that the CIs usually have a duration less than one TV field (16.7 ms), but higher-speed photometric measurements show that they last about 3 ms, and are delayed 3 ms after an initiating cloud–ground lightning stroke; 95% of these initiating strokes are found to be “positive”—i.e., carry positive charges from clouds to ground. The preference for positive initiating strokes is not understood. Theories of the formation of CIs are briefly reviewed. PMID:11038577

A Piezoelectric Unimorph Deformable Mirror Concept by Wafer Transfer for Ultra Large Space Telescopes

NASA Technical Reports Server (NTRS)

Yang, Eui-Hyeok; Shcheglov, Kirill

2002-01-01

Future concepts of ultra large space telescopes include segmented silicon mirrors and inflatable polymer mirrors. Primary mirrors for these systems cannot meet optical surface figure requirements and are likely to generate over several microns of wavefront errors. In order to correct for these large wavefront errors, high stroke optical quality deformable mirrors are required. JPL has recently developed a new technology for transferring an entire wafer-level mirror membrane from one substrate to another. A thin membrane, 100 mm in diameter, has been successfully transferred without using adhesives or polymers. The measured peak-to-valley surface error of a transferred and patterned membrane (1 mm x 1 mm x 0.016 mm) is only 9 nm. The mirror element actuation principle is based on a piezoelectric unimorph. A voltage applied to the piezoelectric layer induces stress in the longitudinal direction causing the film to deform and pull on the mirror connected to it. The advantage of this approach is that the small longitudinal strains obtainable from a piezoelectric material at modest voltages are thus translated into large vertical displacements. Modeling is performed for a unimorph membrane consisting of clamped rectangular membrane with a PZT layer with variable dimensions. The membrane transfer technology is combined with the piezoelectric bimorph actuator concept to constitute a compact deformable mirror device with a large stroke actuation of a continuous mirror membrane, resulting in a compact A0 systems for use in ultra large space telescopes.

Effect of Gravity on Robot-Assisted Motor Training After Chronic Stroke: A Randomized Trial

PubMed Central

Conroy, Susan S.; Whitall, Jill; Dipietro, Laura; Jones-Lush, Lauren M.; Zhan, Min; Finley, Margaret A.; Wittenberg, George F.; Krebs, Hermano I.; Bever, Christopher T.

2015-01-01

Objectives To determine the efficacy of 2 distinct 6-week robot-assisted reaching programs compared with an intensive conventional arm exercise program (ICAE) for chronic, stroke-related upper-extremity (UE) impairment. To examine whether the addition of robot-assisted training out of the horizontal plane leads to improved outcomes. Design Randomized controlled trial, single-blinded, with 12-week follow-up. Setting Research setting in a large medical center. Participants Adults (N=62) with chronic, stroke-related arm weakness stratified by impairment severity using baseline UE motor assessments. Interventions Sixty minutes, 3 times a week for 6 weeks of robot-assisted planar reaching (gravity compensated), combined planar with vertical robot-assisted reaching, or intensive conventional arm exercise program. Main Outcome Measure UE Fugl-Meyer Assessment (FMA) mean change from baseline to final training. Results All groups showed modest gains in the FMA from baseline to final with no significant between group differences. Most change occurred in the planar robot group (mean change ± SD, 2.94± 0.77; 95% confidence interval [CI], 1.40 – 4.47). Participants with greater motor impairment (n=41) demonstrated a larger difference in response (mean change ± SD, 2.29±0.72; 95% CI, 0.85–3.72) for planar robot-assisted exercise compared with the intensive conventional arm exercise program (mean change ± SD, 0.43±0.72; 95% CI, −1.00 to 1.86). Conclusions Chronic UE deficits because of stroke are responsive to intensive motor task training. However, training outside the horizontal plane in a gravity present environment using a combination of vertical with planar robots was not superior to training with the planar robot alone. PMID:21849168

Detection of Lightning-produced NOx by Air Quality Monitoring Stations in Israel

NASA Astrophysics Data System (ADS)

Yair, Y.; Shalev, S.; Saaroni, H.; Ziv, B.

2011-12-01

Lightning is the largest natural source for the production of nitrogen oxides (LtNOx) in the troposphere. Since NOx are greenhouse gases, it is important to know the global production rate of LtNOx for climate studies (present estimates range from 2 to 8 Tg per year) and to model its vertical distribution (Ott et al., 2010). One of the key factors for such an estimate is the yield of a single lightning flash, namely the number of molecules produced for each Joule of energy deposited along the lightning channel. We used lightning stroke data from the Israel Lightning Location System (ILLS) together with NOx data obtained from the national network of air quality monitoring stations operated by the Israeli Ministry of Environmental Protection. Looking for the fingerprints of LtNOx in the general ambient concentrations, usually most affected by pollution from urban sources, we looked only for CG strokes occurring within a radius of 3 km from the location of an air-quality monitoring station. This lowered the number of relevant cases from 605,413 strokes detected in the 2004/5 through 2009/10 seasons to 1,897 strokes. We applied a threshold of > 60kA reducing the number of events to 35. The results showed that there was no consistent rising trend in the NOx concentrations in the hour following the lightning (the lifetime near the ground is expected to be a few hours; Zhang et al., 2003). However, when considering only those events when the prevailing wind was in the direction from the stroke location toward the sensor (7 cases), a clear increase of few ppb following the stroke was observed in 5 cases [see Fig.]. This increase is well correlated with the wind speed, suggesting an effective transport from the stroke location to the sensor. Weaker winds allow dilution and result in smaller observed increases of LtNOx. Separate analysis of additional 17 cases in which the strokes were located < 500 m from the monitoring station (with any peak current above 7 kA) showed no consistent trend. When excluding the 7 events that occurred during rush hour traffic, we found 6 (of 10) cases with an average increase in NOx concentrations of 16 ppb in the hour following the lightning. These results suggest a contribution of CG lightning strokes to the ground level concentrations of NOx. L. E. Ott, K. E. Pickering, G. L. Stenchikov, D. J. Allen, A. J. DeCaria, B. Ridley, R.F. Lin, S. Lang, and W.K. Tao (2010), Production of lightning NOx and its vertical distribution calculated from three dimensional cloud scale chemical transport model simulations, J. Geophys. Res., 115, D04301, doi:10.1029/2009JD011880

Finite Element Approach for the Design of Control Algorithms for Vertical Fin Buffeting Using Strain Actuation

DTIC Science & Technology

2001-06-01

Algorithms for Vertical Fin Buffeting Using Strain Actuation DISTRIBUTION: Approved for public release, distribution unlimited This paper is part of the...UNCLASSIFIED 8-1 Finite Element Approach for the Design of Control Algorithms for Vertical Fin Buffeting Using Strain Actuation Fred Nitzsche...groups), the disturbance (buffet load), and the two output variables (a choice among four Introduction accelerometers and five strain - gauge positions

Design and testing of a novel multi-stroke micropositioning system with variable resolutions.

PubMed

Xu, Qingsong

2014-02-01

Multi-stroke stages are demanded in micro-/nanopositioning applications which require smaller and larger motion strokes with fine and coarse resolutions, respectively. This paper presents the conceptual design of a novel multi-stroke, multi-resolution micropositioning stage driven by a single actuator for each working axis. It eliminates the issue of the interference among different drives, which resides in conventional multi-actuation stages. The stage is devised based on a fully compliant variable stiffness mechanism, which exhibits unequal stiffnesses in different strokes. Resistive strain sensors are employed to offer variable position resolutions in the different strokes. To quantify the design of the motion strokes and coarse/fine resolution ratio, analytical models are established. These models are verified through finite-element analysis simulations. A proof-of-concept prototype XY stage is designed, fabricated, and tested to demonstrate the feasibility of the presented ideas. Experimental results of static and dynamic testing validate the effectiveness of the proposed design.

Observation of incomplete drainage of a branched negative stepped leader system during the initial return stroke, and its implications

NASA Astrophysics Data System (ADS)

Petersen, D.; Beasley, W. H.

2012-12-01

We present high-speed video, taken at 75,000 frames per second, of an anomalous lightning flash that involved two distinct return strokes from different branches of the same branched negative stepped leader system. During the initial return stroke the leader system was incompletely drained, resulting in the continued development of a large side branch. The upper portions of this side branch exhibited a pulse of luminosity during the initial return stroke, but the luminosity did not extend down the branch. The lower portion of the branch continued to develop downward as a negative stepped leader, but at a much slower velocity. Continued stepping activity was observed in this branch as it continued downward at a significantly reduced velocity, finally attaching to the earth 1.8 milliseconds after the main return stroke. The ensuing return stroke was characterized by a slower vertical velocity and weaker luminous pulse. Based on this observation, we coin the term "orphaned branch" to describe a branch of a leader system that is not drained during a return stroke. While our case involves a branch that eventually connected to the ground and produced a return stroke, we also consider the possibility that such branches may also simply cease to progress and effectively deposit large amounts of space charge near their extremities. Such space charge would have a strong influence on subsequent breakdown activity in their vicinity, such as shielding subsequent descending negative stepped leaders or triggering upward positive leaders from earth's surface.

Validity of the growth model of the 'computerized visual perception assessment tool for Chinese characters structures'.

PubMed

Wu, Huey-Min; Li, Cheng-Hsaun; Kuo, Bor-Chen; Yang, Yu-Mao; Lin, Chin-Kai; Wan, Wei-Hsiang

2017-08-01

Morphological awareness is the foundation for the important developmental skills involved with vocabulary, as well as understanding the meaning of words, orthographic knowledge, reading, and writing. Visual perception of space and radicals in two-dimensional positions of Chinese characters' morphology is very important in identifying Chinese characters. The important predictive variables of special and visual perception in Chinese characters identification were investigated in the growth model in this research. The assessment tool is the "Computerized Visual Perception Assessment Tool for Chinese Characters Structures" developed by this study. There are two constructs, basic stroke and character structure. In the basic stroke, there are three subtests of one, two, and more than three strokes. In the character structure, there are three subtests of single-component character, horizontal-compound character, and vertical-compound character. This study used purposive sampling. In the first year, 551 children 4-6 years old participated in the study and were monitored for one year. In the second year, 388 children remained in the study and the successful follow-up rate was 70.4%. This study used a two-wave cross-lagged panel design to validate the growth model of the basic stroke and the character structure. There was significant correlation of the basic stroke and the character structure at different time points. The abilities in the basic stroke and in the character structure steadily developed over time for preschool children. Children's knowledge of the basic stroke effectively predicted their knowledge of the basic stroke and the character structure. Copyright © 2017 Elsevier Ltd. All rights reserved.

Emergency Physician Attitudes, Preferences, and Risk Tolerance for Stroke as a Potential Cause of Dizziness Symptoms

PubMed Central

Kene, Mamata V.; Ballard, Dustin W.; Vinson, David R.; Rauchwerger, Adina S.; Iskin, Hilary R.; Kim, Anthony S.

2015-01-01

Introduction We evaluated emergency physicians’ (EP) current perceptions, practice, and attitudes towards evaluating stroke as a cause of dizziness among emergency department patients. Methods We administered a survey to all EPs in a large integrated healthcare delivery system. The survey included clinical vignettes, perceived utility of historical and exam elements, attitudes about the value of and requisite post-test probability of a clinical prediction rule for dizziness. We calculated descriptive statistics and post-test probabilities for such a clinical prediction rule. Results The response rate was 68% (366/535). Respondents’ median practice tenure was eight years (37% female, 92% emergency medicine board certified). Symptom quality and typical vascular risk factors increased suspicion for stroke as a cause of dizziness. Most respondents reported obtaining head computed tomography (CT) (74%). Nearly all respondents used and felt confident using cranial nerve and limb strength testing. A substantial minority of EPs used the Epley maneuver (49%) and HINTS (head-thrust test, gaze-evoked nystagmus, and skew deviation) testing (30%); however, few EPs reported confidence in these tests’ bedside application (35% and 16%, respectively). Respondents favorably viewed applying a properly validated clinical prediction rule for assessment of immediate and 30-day stroke risk, but indicated it would have to reduce stroke risk to <0.5% to be clinically useful. Conclusion EPs report relying on symptom quality, vascular risk factors, simple physical exam elements, and head CT to diagnose stroke as the cause of dizziness, but would find a validated clinical prediction rule for dizziness helpful. A clinical prediction rule would have to achieve a 0.5% post-test stroke probability for acceptability. PMID:26587108

Stroke: Working toward a Prioritized World Agenda

PubMed Central

Hachinski, Vladimir; Donnan, Geoffrey A.; Gorelick, Philip B.; Hacke, Werner; Cramer, Steven C.; Kaste, Markku; Fisher, Marc; Brainin, Michael; Buchan, Alastair M.; Lo, Eng H.; Skolnick, Brett E.; Furie, Karen L.; Hankey, Graeme J.; Kivipelto, Miia; Morris, John; Rothwell, Peter M.; Sacco, Ralph L.; Smith, Sidney C.; Wang, Yulun; Bryer, Alan; Ford, Gary A.; Iadecola, Costantino; Martins, Sheila C.O.; Saver, Jeff; Skvortsova, Veronika; Bayley, Mark; Bednar, Martin M.; Duncan, Pamela; Enney, Lori; Finklestein, Seth; Jones, Theresa A.; Kalra, Lalit; Kleim, Jeff; Nitkin, Ralph; Teasell, Robert; Weiller, Cornelius; Desai, Bhupat; Goldberg, Mark P.; Heiss, Wolf-Dieter; Saarelma, Osmo; Schwamm, Lee H.; Shinohara, Yukito; Trivedi, Bhargava; Wahlgren, Nils; Wong, Lawrence K.; Hakim, Antoine; Norrving, Bo; Prudhomme, Stephen; Bornstein, Natan M.; Davis, Stephen M.; Goldstein, Larry B.; Leys, Didier; Tuomilehto, Jaakko

2013-01-01

Background and Purpose The aim of the Synergium was to devise and prioritize new ways of accelerating progress in reducing the risks, effects, and consequences of stroke. Methods Preliminary work was performed by 7 working groups of stroke leaders followed by a synergium (a forum for working synergistically together) with approximately 100 additional participants. The resulting draft document had further input from contributors outside the synergium. Results Recommendations of the Synergium are: Basic Science, Drug Development and Technology: There is a need to develop: (1) New systems of working together to break down the prevalent ‘silo’ mentality; (2) New models of vertically integrated basic, clinical, and epidemiological disciplines; and (3) Efficient methods of identifying other relevant areas of science. Stroke Prevention: (1) Establish a global chronic disease prevention initiative with stroke as a major focus. (2) Recognize not only abrupt clinical stroke, but subtle subclinical stroke, the commonest type of cerebrovascular disease, leading to impairments of executive function. (3) Develop, implement and evaluate a population approach for stroke prevention. (4) Develop public health communication strategies using traditional and novel (e.g., social media/marketing) techniques. Acute Stroke Management: Continue the establishment of stroke centers, stroke units, regional systems of emergency stroke care and telestroke networks. Brain Recovery and Rehabilitation: (1) Translate best neuroscience, including animal and human studies, into poststroke recovery research and clinical care. (2) Standardize poststroke rehabilitation based on best evidence. (3) Develop consensus on, then implementation of, standardized clinical and surrogate assessments. (4) Carry out rigorous clinical research to advance stroke recovery. Into the 21st Century: Web, Technology and Communications: (1) Work toward global unrestricted access to stroke-related information. (2) Build centralized electronic archives and registries. Foster Cooperation Among Stakeholders (large stroke organizations, nongovernmental organizations, governments, patient organizations and industry) to enhance stroke care. Educate and energize professionals, patients, the public and policy makers by using a ‘Brain Health’ concept that enables promotion of preventive measures. Conclusions To accelerate progress in stroke, we must reach beyond the current status scientifically, conceptually, and pragmatically. Advances can be made not only by doing, but ceasing to do. Significant savings in time, money, and effort could result from discontinuing practices driven by unsubstantiated opinion, unproven approaches, and financial gain. Systematic integration of knowledge into programs coupled with careful evaluation can speed the pace of progress PMID:20636706

Stroke: Working toward a Prioritized World Agenda

PubMed Central

Hachinski, Vladimir; Donnan, Geoffrey A.; Gorelick, Philip B.; Hacke, Werner; Cramer, Steven C.; Kaste, Markku; Fisher, Marc; Brainin, Michael; Buchan, Alastair M.; Lo, Eng H.; Skolnick, Brett E.; Furie, Karen L.; Hankey, Graeme J.; Kivipelto, Miia; Morris, John; Rothwell, Peter M.; Sacco, Ralph L.; Smith, Jr., Sidney C.; Wang, Yulun; Bryer, Alan; Ford, Gary A.; Iadecola, Costantino; Martins, Sheila C.O.; Saver, Jeff; Skvortsova, Veronika; Bayley, Mark; Bednar, Martin M.; Duncan, Pamela; Enney, Lori; Finklestein, Seth; Jones, Theresa A.; Kalra, Lalit; Kleim, Jeff; Nitkin, Ralph; Teasell, Robert; Weiller, Cornelius; Desai, Bhupat; Goldberg, Mark P.; Heiss, Wolf-Dieter; Saarelma, Osmo; Schwamm, Lee H.; Shinohara, Yukito; Trivedi, Bhargava; Wahlgren, Nils; Wong, Lawrence K.; Hakim, Antoine; Norrving, Bo; Prudhomme, Stephen; Bornstein, Natan M.; Davis, Stephen M.; Goldstein, Larry B.; Leys, Didier; Tuomilehto, Jaakko

2010-01-01

Background and Purpose The aim of the Synergium was to devise and prioritize new ways of accelerating progress in reducing the risks, effects, and consequences of stroke. Methods Preliminary work was performed by 7 working groups of stroke leaders followed by a synergium (a forum for working synergistically together) with approximately 100 additional participants. The resulting draft document had further input from contributors outside the synergium. Results Recommendations of the Synergium are: Basic Science, Drug Development and Technology: There is a need to develop: (1) New systems of working together to break down the prevalent ‘silo’ mentality; (2) New models of vertically integrated basic, clinical, and epidemiological disciplines; and (3) Efficient methods of identifying other relevant areas of science. Stroke Prevention: (1) Establish a global chronic disease prevention initiative with stroke as a major focus. (2) Recognize not only abrupt clinical stroke, but subtle subclinical stroke, the commonest type of cerebrovascular disease, leading to impairments of executive function. (3) Develop, implement and evaluate a population approach for stroke prevention. (4) Develop public health communication strategies using traditional and novel (e.g., social media/marketing) techniques. Acute Stroke Management: Continue the establishment of stroke centers, stroke units, regional systems of emergency stroke care and telestroke networks. Brain Recovery and Rehabilitation: (1) Translate best neuroscience, including animal and human studies, into poststroke recovery research and clinical care. (2) Standardize poststroke rehabilitation based on best evidence. (3) Develop consensus on, then implementation of, standardized clinical and surrogate assessments. (4) Carry out rigorous clinical research to advance stroke recovery. Into the 21st Century: Web, Technology and Communications: (1) Work toward global unrestricted access to stroke-related information. (2) Build centralized electronic archives and registries. Foster Cooperation Among Stakeholders (large stroke organizations, nongovernmental organizations, governments, patient organizations and industry) to enhance stroke care. Educate and energize professionals, patients, the public and policy makers by using a ‘Brain Health’ concept that enables promotion of preventive measures. Conclusions To accelerate progress in stroke, we must reach beyond the current status scientifically, conceptually, and pragmatically. Advances can be made not only by doing, but ceasing to do. Significant savings in time, money, and effort could result from discontinuing practices driven by unsubstantiated opinion, unproven approaches, and financial gain. Systematic integration of knowledge into programs coupled with careful evaluation can speed the pace of progress. PMID:20516682

Stroke: Working Toward a Prioritized World Agenda

PubMed Central

Hachinski, Vladimir; Donnan, Geoffrey A.; Gorelick, Philip B.; Hacke, Werner; Cramer, Steven C.; Kaste, Markku; Fisher, Marc; Brainin, Michael; Buchan, Alastair M.; Lo, Eng H.; Skolnick, Brett E.; Furie, Karen L.; Hankey, Graeme J.; Kivipelto, Miia; Morris, John; Rothwell, Peter M.; Sacco, Ralph L.; Smith, Sidney C.; Wang, Yulun; Bryer, Alan; Ford, Gary A.; Iadecola, Costantino; Martins, Sheila C.O.; Saver, Jeff; Skvortsova, Veronika; Bayley, Mark; Bednar, Martin M.; Duncan, Pamela; Enney, Lori; Finklestein, Seth; Jones, Theresa A.; Kalra, Lalit; Kleim, Jeff; Nitkin, Ralph; Teasell, Robert; Weiller, Cornelius; Desai, Bhupat; Goldberg, Mark P.; Heiss, Wolf-Dieter; Saarelma, Osmo; Schwamm, Lee H.; Shinohara, Yukito; Trivedi, Bhargava; Wahlgren, Nils; Wong, Lawrence K.; Hakim, Antoine; Norrving, Bo; Prudhomme, Stephen; Bornstein, Natan M.; Davis, Stephen M.; Edin, FRCP; Goldstein, Larry B.; Leys, Didier; Tuomilehto, Jaakko

2013-01-01

Background and Purpose The aim of the Synergium was to devise and prioritize new ways of accelerating progress in reducing the risks, effects, and consequences of stroke. Methods Preliminary work was performed by 7 working groups of stroke leaders followed by a synergium (a forum for working synergistically together) with approximately 100 additional participants. The resulting draft document had further input from contributors outside the synergium. Results Recommendations of the Synergium are: Basic Science, Drug Development and Technology: There is a need to develop: (1) New systems of working together to break down the prevalent “silo” mentality; (2) New models of vertically integrated basic, clinical, and epidemiological disciplines; and (3) Efficient methods of identifying other relevant areas of science. Stroke Prevention: (1) Establish a global chronic disease prevention initiative with stroke as a major focus. (2) Recognize not only abrupt clinical stroke, but subtle subclinical stroke, the commonest type of cerebrovascular disease, leading to impairments of executive function. (3) Develop, implement and evaluate a population approach for stroke prevention. (4) Develop public health communication strategies using traditional and novel (eg, social media/marketing) techniques. Acute Stroke Management: Continue the establishment of stroke centers, stroke units, regional systems of emergency stroke care and telestroke networks. Brain Recovery and Rehabilitation: (1) Translate best neuroscience, including animal and human studies, into poststroke recovery research and clinical care. (2) Standardize poststroke rehabilitation based on best evidence. (3) Develop consensus on, then implementation of, standardized clinical and surrogate assessments. (4) Carry out rigorous clinical research to advance stroke recovery. Into the 21st Century: Web, Technology and Communications: (1) Work toward global unrestricted access to stroke-related information. (2) Build centralized electronic archives and registries. Foster Cooperation Among Stakeholders (large stroke organizations, nongovernmental organizations, governments, patient organizations and industry) to enhance stroke care. Educate and energize professionals, patients, the public and policy makers by using a “Brain Health” concept that enables promotion of preventive measures. Conclusions To accelerate progress in stroke, we must reach beyond the current status scientifically, conceptually, and pragmatically. Advances can be made not only by doing, but ceasing to do. Significant savings in time, money, and effort could result from discontinuing practices driven by unsubstantiated opinion, unproven approaches, and financial gain. Systematic integration of knowledge into programs coupled with careful evaluation can speed the pace of progress. PMID:20498453

Stroke: working toward a prioritized world agenda.

PubMed

Hachinski, Vladimir; Donnan, Geoffrey A; Gorelick, Philip B; Hacke, Werner; Cramer, Steven C; Kaste, Markku; Fisher, Marc; Brainin, Michael; Buchan, Alastair M; Lo, Eng H; Skolnick, Brett E; Furie, Karen L; Hankey, Graeme J; Kivipelto, Miia; Morris, John; Rothwell, Peter M; Sacco, Ralph L; Smith, Sidney C; Wang, Yulun; Bryer, Alan; Ford, Gary A; Iadecola, Costantino; Martins, Sheila C O; Saver, Jeff; Skvortsova, Veronika; Bayley, Mark; Bednar, Martin M; Duncan, Pamela; Enney, Lori; Finklestein, Seth; Jones, Theresa A; Kalra, Lalit; Kleim, Jeff; Nitkin, Ralph; Teasell, Robert; Weiller, Cornelius; Desai, Bhupat; Goldberg, Mark P; Heiss, Wolf-Dieter; Saarelma, Osmo; Schwamm, Lee H; Shinohara, Yukito; Trivedi, Bhargava; Wahlgren, Nils; Wong, Lawrence K; Hakim, Antoine; Norrving, Bo; Prudhomme, Stephen; Bornstein, Natan M; Davis, Stephen M; Goldstein, Larry B; Leys, Didier; Tuomilehto, Jaakko

2010-01-01

The aim of the Synergium was to devise and prioritize new ways of accelerating progress in reducing the risks, effects, and consequences of stroke. Preliminary work was performed by 7 working groups of stroke leaders followed by a synergium (a forum for working synergistically together) with approximately 100 additional participants. The resulting draft document had further input from contributors outside the synergium. Recommendations of the Synergium are: Basic Science, Drug Development and Technology: There is a need to develop: (1) New systems of working together to break down the prevalent 'silo' mentality; (2) New models of vertically integrated basic, clinical, and epidemiological disciplines; and (3) Efficient methods of identifying other relevant areas of science. Stroke Prevention: (1) Establish a global chronic disease prevention initiative with stroke as a major focus. (2) Recognize not only abrupt clinical stroke, but subtle subclinical stroke, the commonest type of cerebrovascular disease, leading to impairments of executive function. (3) Develop, implement and evaluate a population approach for stroke prevention. (4) Develop public health communication strategies using traditional and novel (e.g., social media/marketing) techniques. Acute Stroke Management: Continue the establishment of stroke centers, stroke units, regional systems of emergency stroke care and telestroke networks. Brain Recovery and Rehabilitation: (1) Translate best neuroscience, including animal and human studies, into poststroke recovery research and clinical care. (2) Standardize poststroke rehabilitation based on best evidence. (3) Develop consensus on, then implementation of, standardized clinical and surrogate assessments. (4) Carry out rigorous clinical research to advance stroke recovery. Into the 21st Century: Web, Technology and Communications: (1) Work toward global unrestricted access to stroke-related information. (2) Build centralized electronic archives and registries. Foster Cooperation Among Stakeholders (large stroke organizations, nongovernmental organizations, governments, patient organizations and industry) to enhance stroke care. Educate and energize professionals, patients, the public and policy makers by using a 'Brain Health' concept that enables promotion of preventive measures. To accelerate progress in stroke, we must reach beyond the current status scientifically, conceptually, and pragmatically. Advances can be made not only by doing, but ceasing to do. Significant savings in time, money, and effort could result from discontinuing practices driven by unsubstantiated opinion, unproven approaches, and financial gain. Systematic integration of knowledge into programs coupled with careful evaluation can speed the pace of progress. Copyright (c) 2010 American Heart Association. Inc., S. Karger AG, Basel, and John Wiley & Sons, Inc.

Stroke: working toward a prioritized world agenda.

PubMed

Hachinski, Vladimir; Donnan, Geoffrey A; Gorelick, Philip B; Hacke, Werner; Cramer, Steven C; Kaste, Markku; Fisher, Marc; Brainin, Michael; Buchan, Alastair M; Lo, Eng H; Skolnick, Brett E; Furie, Karen L; Hankey, Graeme J; Kivipelto, Miia; Morris, John; Rothwell, Peter M; Sacco, Ralph L; Smith, Sidney C; Wang, Yulun; Bryer, Alan; Ford, Gary A; Iadecola, Costantino; Martins, Sheila C O; Saver, Jeff; Skvortsova, Veronika; Bayley, Mark; Bednar, Martin M; Duncan, Pamela; Enney, Lori; Finklestein, Seth; Jones, Theresa A; Kalra, Lalit; Kleim, Jeff; Nitkin, Ralph; Teasell, Robert; Weiller, Cornelius; Desai, Bhupat; Goldberg, Mark P; Heiss, Wolf-Dieter; Saarelma, Osmo; Schwamm, Lee H; Shinohara, Yukito; Trivedi, Bhargava; Wahlgren, Nils; Wong, Lawrence K; Hakim, Antoine; Norrving, Bo; Prudhomme, Stephen; Bornstein, Natan M; Davis, Stephen M; Goldstein, Larry B; Leys, Didier; Tuomilehto, Jaakko

2010-06-01

The aim of the Synergium was to devise and prioritize new ways of accelerating progress in reducing the risks, effects, and consequences of stroke. Preliminary work was performed by 7 working groups of stroke leaders followed by a synergium (a forum for working synergistically together) with approximately 100 additional participants. The resulting draft document had further input from contributors outside the synergium. Recommendations of the Synergium are: Basic Science, Drug Development and Technology: There is a need to develop: (1) New systems of working together to break down the prevalent "silo" mentality; (2) New models of vertically integrated basic, clinical, and epidemiological disciplines; and (3) Efficient methods of identifying other relevant areas of science. Stroke Prevention: (1) Establish a global chronic disease prevention initiative with stroke as a major focus. (2) Recognize not only abrupt clinical stroke, but subtle subclinical stroke, the commonest type of cerebrovascular disease, leading to impairments of executive function. (3) Develop, implement and evaluate a population approach for stroke prevention. (4) Develop public health communication strategies using traditional and novel (eg, social media/marketing) techniques. Acute Stroke Management: Continue the establishment of stroke centers, stroke units, regional systems of emergency stroke care and telestroke networks. Brain Recovery and Rehabilitation: (1) Translate best neuroscience, including animal and human studies, into poststroke recovery research and clinical care. (2) Standardize poststroke rehabilitation based on best evidence. (3) Develop consensus on, then implementation of, standardized clinical and surrogate assessments. (4) Carry out rigorous clinical research to advance stroke recovery. Into the 21st Century: Web, Technology and Communications: (1) Work toward global unrestricted access to stroke-related information. (2) Build centralized electronic archives and registries. Foster Cooperation Among Stakeholders (large stroke organizations, nongovernmental organizations, governments, patient organizations and industry) to enhance stroke care. Educate and energize professionals, patients, the public and policy makers by using a "Brain Health" concept that enables promotion of preventive measures. To accelerate progress in stroke, we must reach beyond the current status scientifically, conceptually, and pragmatically. Advances can be made not only by doing, but ceasing to do. Significant savings in time, money, and effort could result from discontinuing practices driven by unsubstantiated opinion, unproven approaches, and financial gain. Systematic integration of knowledge into programs coupled with careful evaluation can speed the pace of progress.

Stroke: working toward a prioritized world agenda.

PubMed

Hachinski, Vladimir; Donnan, Geoffrey A; Gorelick, Philip B; Hacke, Werner; Cramer, Steven C; Kaste, Markku; Fisher, Marc; Brainin, Michael; Buchan, Alastair M; Lo, Eng H; Skolnick, Brett E; Furie, Karen L; Hankey, Graeme J; Kivipelto, Miia; Morris, John; Rothwell, Peter M; Sacco, Ralph L; Smith, Sidney C; Wang, Yulun; Bryer, Alan; Ford, Gary A; Iadecola, Costantino; Martins, Sheila C O; Saver, Jeff; Skvortsova, Veronika; Bayley, Mark; Bednar, Martin M; Duncan, Pamela; Enney, Lori; Finklestein, Seth; Jones, Theresa A; Kalra, Lalit; Kleim, Jeff; Nitkin, Ralph; Teasell, Robert; Weiller, Cornelius; Desai, Bhupat; Goldberg, Mark P; Heiss, Wolf-Dieter; Saarelma, Osmo; Schwamm, Lee H; Shinohara, Yukito; Trivedi, Bhargava; Wahlgren, Nils; Wong, Lawrence K; Hakim, Antoine; Norrving, Bo; Prudhomme, Stephen; Bornstein, Natan M; Davis, Stephen M; Goldstein, Larry B; Leys, Didier; Tuomilehto, Jaakko

2010-08-01

The aim of the Synergium was to devise and prioritize new ways of accelerating progress in reducing the risks, effects, and consequences of stroke. Preliminary work was performed by seven working groups of stroke leaders followed by a synergium (a forum for working synergistically together) with approximately 100 additional participants. The resulting draft document had further input from contributors outside the synergium. Recommendations of the Synergium are: Basic Science, Drug Development and Technology: There is a need to develop: (1) New systems of working together to break down the prevalent 'silo' mentality; (2) New models of vertically integrated basic, clinical, and epidemiological disciplines; and (3) Efficient methods of identifying other relevant areas of science. Stroke Prevention: (1) Establish a global chronic disease prevention initiative with stroke as a major focus. (2) Recognize not only abrupt clinical stroke, but subtle subclinical stroke, the commonest type of cerebrovascular disease, leading to impairments of executive function. (3) Develop, implement and evaluate a population approach for stroke prevention. (4) Develop public health communication strategies using traditional and novel (eg, social media/marketing) techniques. Acute Stroke Management: Continue the establishment of stroke centers, stroke units, regional systems of emergency stroke care and telestroke networks. Brain Recovery and Rehabilitation: (1) Translate best neuroscience, including animal and human studies, into poststroke recovery research and clinical care. (2) Standardize poststroke rehabilitation based on best evidence. (3) Develop consensus on, then implementation of, standardized clinical and surrogate assessments. (4) Carry out rigorous clinical research to advance stroke recovery. Into the 21st Century: Web, Technology and Communications: (1) Work toward global unrestricted access to stroke-related information. (2) Build centralized electronic archives and registries. Foster Cooperation Among Stakeholders (large stroke organizations, nongovernmental organizations, governments, patient organizations and industry) to enhance stroke care. Educate and energize professionals, patients, the public and policy makers by using a 'Brain Health' concept that enables promotion of preventive measures. To accelerate progress in stroke, we must reach beyond the current status scientifically, conceptually, and pragmatically. Advances can be made not only by doing, but ceasing to do. Significant savings in time, money, and effort could result from discontinuing practices driven by unsubstantiated opinion, unproven approaches, and financial gain. Systematic integration of knowledge into programs coupled with careful evaluation can speed the pace of progress.

A high-order staggered finite-element vertical discretization for non-hydrostatic atmospheric models

DOE PAGES

Guerra, Jorge E.; Ullrich, Paul A.

2016-06-01

Atmospheric modeling systems require economical methods to solve the non-hydrostatic Euler equations. Two major differences between hydrostatic models and a full non-hydrostatic description lies in the vertical velocity tendency and numerical stiffness associated with sound waves. In this work we introduce a new arbitrary-order vertical discretization entitled the staggered nodal finite-element method (SNFEM). Our method uses a generalized discrete derivative that consistently combines the discontinuous Galerkin and spectral element methods on a staggered grid. Our combined method leverages the accurate wave propagation and conservation properties of spectral elements with staggered methods that eliminate stationary (2Δ x) modes. Furthermore, high-order accuracymore » also eliminates the need for a reference state to maintain hydrostatic balance. In this work we demonstrate the use of high vertical order as a means of improving simulation quality at relatively coarse resolution. We choose a test case suite that spans the range of atmospheric flows from predominantly hydrostatic to nonlinear in the large-eddy regime. Lastly, our results show that there is a distinct benefit in using the high-order vertical coordinate at low resolutions with the same robust properties as the low-order alternative.« less

A high-order staggered finite-element vertical discretization for non-hydrostatic atmospheric models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guerra, Jorge E.; Ullrich, Paul A.

Atmospheric modeling systems require economical methods to solve the non-hydrostatic Euler equations. Two major differences between hydrostatic models and a full non-hydrostatic description lies in the vertical velocity tendency and numerical stiffness associated with sound waves. In this work we introduce a new arbitrary-order vertical discretization entitled the staggered nodal finite-element method (SNFEM). Our method uses a generalized discrete derivative that consistently combines the discontinuous Galerkin and spectral element methods on a staggered grid. Our combined method leverages the accurate wave propagation and conservation properties of spectral elements with staggered methods that eliminate stationary (2Δ x) modes. Furthermore, high-order accuracymore » also eliminates the need for a reference state to maintain hydrostatic balance. In this work we demonstrate the use of high vertical order as a means of improving simulation quality at relatively coarse resolution. We choose a test case suite that spans the range of atmospheric flows from predominantly hydrostatic to nonlinear in the large-eddy regime. Lastly, our results show that there is a distinct benefit in using the high-order vertical coordinate at low resolutions with the same robust properties as the low-order alternative.« less

Hawkmoth flight performance in tornado-like whirlwind vortices.

PubMed

Ortega-Jimenez, Victor Manuel; Mittal, Rajat; Hedrick, Tyson L

2014-06-01

Vertical vortex systems such as tornadoes dramatically affect the flight control and stability of aircraft. However, the control implications of smaller scale vertically oriented vortex systems for small fliers such as animals or micro-air vehicles are unknown. Here we examined the flapping kinematics and body dynamics of hawkmoths performing hovering flights (controls) and maintaining position in three different whirlwind intensities with transverse horizontal velocities of 0.7, 0.9 and 1.2 m s(-1), respectively, generated in a vortex chamber. The average and standard deviation of yaw and pitch were respectively increased and reduced in comparison with hovering flights. Average roll orientation was unchanged in whirlwind flights but was more variable from wingbeat to wingbeat than in hovering. Flapping frequency remained unchanged. Wingbeat amplitude was lower and the average stroke plane angle was higher. Asymmetry was found in the angle of attack between right and left wings during both downstroke and upstroke at medium and high vortex intensities. Thus, hawkmoth flight control in tornado-like vortices is achieved by a suite of asymmetric and symmetric changes to wingbeat amplitude, stroke plane angle and principally angle of attack.

Complex neurological symptoms in bilateral thalamic stroke due to Percheron artery occlusion.

PubMed

Caruso, Paola; Manganotti, Paolo; Moretti, Rita

2017-01-01

The artery of Percheron is a rare anatomical variant where a single thalamic perforating artery arises from the proximal posterior cerebral artery (P1 segment) between the basilar artery and the posterior communicating artery and supplies the rostral mesencephalon and both paramedian territories of the thalami. Almost one-third of human brains present this variant. Occlusion of the artery of Percheron mostly results in a bilateral medial thalamic infarction, which usually manifests with altered consciousness (including coma), vertical gaze paresis, and cognitive disturbance. The presentation is similar to the "top of the basilar syndrome", and early recognition should be prompted. We describe the case of a young female with this vessel variant who experienced a bilateral thalamic stroke. Magnetic resonance angiography demonstrated bilateral thalamic infarcts and a truncated artery of Percheron. Occlusion of the vessel was presumably due to embolism from a patent foramen ovale. Thrombolysis was performed, with incomplete symptom remission, cognitive impairment, and persistence of speech disorders. Early recognition and treatment of posterior circulation strokes is mandatory, and further investigation for underlying stroke etiologies is needed.

The provision of feedback through computer-based technology to promote self-managed post-stroke rehabilitation in the home.

PubMed

Parker, Jack; Mawson, Susan; Mountain, Gail; Nasr, Nasrin; Davies, Richard; Zheng, Huiru

2014-11-01

Building on previous research findings, this article describes the development of the feedback interfaces for a Personalised Self-Managed Rehabilitation System (PSMrS) for home-based post-stroke rehabilitation using computer-based technology. Embedded within a realistic evaluative methodological approach, the development of the feedback interfaces for the PSMrS involved the incorporation of existing and emerging theories and a hybrid of health and social sciences research and user-centred design methods. User testing confirmed that extrinsic feedback for home-based post-stroke rehabilitation through computer-based technology needs to be personalisable, accurate, rewarding and measurable. In addition, user testing also confirmed the feasibility of using specific components of the PSMrS. A number of key elements are crucial for the development and potential utilisation of technology in what is an inevitable shift towards the use of innovative methods of delivering post-stroke rehabilitation. This includes the specific elements that are essential for the promotion of self-managed rehabilitation and rehabilitative behaviour change; the impact of the context on the mechanisms; and, importantly, the need for reliability and accuracy of the technology.

Pilot study of a robotic protocol to treat shoulder subluxation in patients with chronic stroke

PubMed Central

2013-01-01

Background Shoulder subluxation is a frequent complication of motor impairment after stroke, leading to soft tissue damage, stretching of the joint capsule, rotator cuff injury, and in some cases pain, thus limiting use of the affected extremity beyond weakness. In this pilot study, we determined whether robotic treatment of chronic shoulder subluxation can lead to functional improvement and whether any improvement was robust. Methods 18 patients with chronic stroke (3.9 ± 2.9 years from acute stroke), completed 6 weeks of robotic training using the linear shoulder robot. Training was performed 3 times per week on alternate days. Each session consisted of 3 sets of 320 repetitions of the affected arm, and the robotic protocol alternated between training vertical arm movements, shoulder flexion and extension, in an anti-gravity plane, and training horizontal arm movements, scapular protraction and retraction, in a gravity eliminated plane. Results Training with the linear robot improved shoulder stability, motor power, and resulted in improved functional outcomes that were robust 3 months after training. Conclusion In this uncontrolled pilot study, the robotic protocol effectively treated shoulder subluxation in chronic stroke patients. Treatment of subluxation can lead to improved functional use of the affected arm, likely by increasing motor power in the trained muscles. PMID:23914834

Pilot study of a robotic protocol to treat shoulder subluxation in patients with chronic stroke.

PubMed

Dohle, Carolin I; Rykman, Avrielle; Chang, Johanna; Volpe, Bruce T

2013-08-05

Shoulder subluxation is a frequent complication of motor impairment after stroke, leading to soft tissue damage, stretching of the joint capsule, rotator cuff injury, and in some cases pain, thus limiting use of the affected extremity beyond weakness. In this pilot study, we determined whether robotic treatment of chronic shoulder subluxation can lead to functional improvement and whether any improvement was robust. 18 patients with chronic stroke (3.9 ± 2.9 years from acute stroke), completed 6 weeks of robotic training using the linear shoulder robot. Training was performed 3 times per week on alternate days. Each session consisted of 3 sets of 320 repetitions of the affected arm, and the robotic protocol alternated between training vertical arm movements, shoulder flexion and extension, in an anti-gravity plane, and training horizontal arm movements, scapular protraction and retraction, in a gravity eliminated plane. Training with the linear robot improved shoulder stability, motor power, and resulted in improved functional outcomes that were robust 3 months after training. In this uncontrolled pilot study, the robotic protocol effectively treated shoulder subluxation in chronic stroke patients. Treatment of subluxation can lead to improved functional use of the affected arm, likely by increasing motor power in the trained muscles.

Ground reaction force analysed with correlation coefficient matrix in group of stroke patients.

PubMed

Szczerbik, Ewa; Krawczyk, Maciej; Syczewska, Małgorzata

2014-01-01

Stroke is the third cause of death in contemporary society and causes many disorders. Clinical scales, ground reaction force (GRF) and objective gait analysis are used for assessment of patient's rehabilitation progress during treatment. The goal of this paper is to assess whether signal correlation coefficient matrix applied to GRF can be used for evaluation of the status of post-stroke patients. A group of patients underwent clinical assessment and instrumented gait analysis simultaneously three times. The difference between components of patient's GRF (vertical, fore/aft, med/lat) and normal ones (reference GRF of healthy subjects) was calculated as correlation coefficient. Patients were divided into two groups ("worse" and "better") based on the clinical functional scale tests done at the beginning of rehabilitation process. The results obtained by these two groups were compared using statistical analysis. An increase of median value of correlation coefficient is observed in all components of GRF, but only in non-paretic leg. Analysis of GRF signal can be helpful in assessment of post-stroke patients during rehabilitation. Improvement in stroke patients was observed in non-paretic leg of the "worse" group. GRF analysis should not be the only tool for objective validation of patient's improvement, but could be used as additional source of information.

Dynamics of thin-film piezoelectric microactuators with large vertical stroke subject to multi-axis coupling and fabrication asymmetries

NASA Astrophysics Data System (ADS)

Choi, Jongsoo; Wang, Thomas; Oldham, Kenn

2018-01-01

The high performance and small size of MEMS based scanners has allowed various optical imaging techniques to be realized in a small form factor. Many such devices are resonant scanners, and thus their linear and nonlinear dynamic behaviors have been studied in the past. Thin-film piezoelectric materials, in contrast, provide sufficient energy density to achieve both large static displacements and high-frequency resonance, but large deformation can in turn influence dynamic scanner behavior. This paper reports on the influence of very large stroke translation of a piezoelectric vertical actuator on its resonant behavior, which may not be otherwise explained fully by common causes of resonance shift such as beam stiffening or nonlinear forcing. To examine the change of structural compliance over the course of scanner motion, a model has been developed that includes internal forces from residual stress and the resultant additional multi-axis coupling among actuator leg structures. Like some preceding vertical scanning micro-actuators, the scanner of this work has four legs, with each leg featuring four serially connected thin-film PZT unimorphs that allow the scanner to generate larger than 400 µm of vertical displacement at 14 V DC. Using an excitation near one or more resonances, the input voltage can be lowered, and complementary multi-axis rotations can be also generated, but change of the resonant frequencies with scanner height needs to be understood to maximize scanner performance. The presented model well predicts the experimental observation of the decrease of the resonant frequencies of the scanner with the increase of a dc bias voltage. Also, the effects of the magnitude and uniformity of residual stress across the scanner structure on the natural frequencies have been studied.

Characterization of vertical electric fields 500 m and 30 m from triggered lightning

NASA Astrophysics Data System (ADS)

Rubenstein, M.; Rachidi, F.; Uman, M. A.; Thottappillil, R.; Rakov, V. A.; Nucci, C. A.

1995-05-01

Vertical electric field waveforms of leader-return stroke sequences measured 500 m and 30 m from rocket-triggered lightning are presented. The 500-m data were recorded during the summer of 1986, the 30-m data during the summer of 1991, both at the NASA Kennedy Space Center, Florida. The 40 leader-return stroke field waveforms at 500 m and the 8 waveforms at 30 m all appear as asymmetrical V-shaped pulses, the bottom of the V being associated with the transition from the leader to the return stroke. Only two waveforms at 30 m were suitable for quantitative analysis. The widths of the V at half of peak value for these are 1.8 and 5.0 μs, while for the 500-m data they are 1 to 2 orders of magnitude greater, with a median value of 100 μs. Applying a widely used and simple leader model to the measured leader electric fields at 500 m, we infer, for the bottom kilometer or so of the leader channel, leader speeds between 2×106 and 2×107 m/s and leader charges per unit length of 0.02×10-3 to 0.08×10-3 C/m. From the two measured leader electric field changes at 30 m we infer, using the same leader model, for the bottom 100 meters or so of the leader channel, speeds of 3×107 and 1×107 m/s (the corresponding measured waveform half widths are 1.8 μs and 5.0 μs) and charges per unit length of 0.14×10-3 and 0.02×10-3 C/m (the corresponding measured leader field changes are 81 kV/m and 12 kV/m). The corresponding measured return stroke peak currents for the above two cases are 40 kA and 7 kA, respectively. A positive correlation is observed between the magnitude of the leader field change at 500 m and the ensuing return stroke current peak.

Neuroplasticity in post-stroke gait recovery and noninvasive brain stimulation

PubMed Central

Xu, Yi; Hou, Qing-hua; Russell, Shawn D.; Bennett, Bradford C.; Sellers, Andrew J.; Lin, Qiang; Huang, Dong-feng

2015-01-01

Gait disorders drastically affect the quality of life of stroke survivors, making post-stroke rehabilitation an important research focus. Noninvasive brain stimulation has potential in facilitating neuroplasticity and improving post-stroke gait impairment. However, a large inter-individual variability in the response to noninvasive brain stimulation interventions has been increasingly recognized. We first review the neurophysiology of human gait and post-stroke neuroplasticity for gait recovery, and then discuss how noninvasive brain stimulation techniques could be utilized to enhance gait recovery. While post-stroke neuroplasticity for gait recovery is characterized by use-dependent plasticity, it evolves over time, is idiosyncratic, and may develop maladaptive elements. Furthermore, noninvasive brain stimulation has limited reach capability and is facilitative-only in nature. Therefore, we recommend that noninvasive brain stimulation be used adjunctively with rehabilitation training and other concurrent neuroplasticity facilitation techniques. Additionally, when noninvasive brain stimulation is applied for the rehabilitation of gait impairment in stroke survivors, stimulation montages should be customized according to the specific types of neuroplasticity found in each individual. This could be done using multiple mapping techniques. PMID:26889202

'Hip-hop' stroke: a stroke educational program for elementary school children living in a high-risk community.

PubMed

Williams, Olajide; Noble, James M

2008-10-01

Public stroke recognition is poor and poses a barrier to acute stroke treatment. We describe a stroke literacy program that teaches elementary school children in high-risk communities to recognize stroke and form an urgent action plan; we then present results of an intervention study using the program. "Hip-Hop" Stroke uses culturally and age-appropriate music and dance to enhance an interactive didactic curriculum including the FAST mnemonic (Facial droop, Arm weakness, Speech disturbance, Time to call 911). The program occurred in central Harlem, New York City, a community with high stroke risk. During the 2006 to 2007 school year, 582 fourth, fifth, and sixth graders (9 to 11 years of age) participated in 1-hour sessions over 3 consecutive days. Stroke knowledge was tested before and after the program with a 94% group participant retention. Students learned and retained knowledge well for stroke localization (20% correct before intervention, 93% correct immediately afterward, and 86% correct after 3-month delay; P<0.001 both posttests versus baseline), the term "brain attack" (16% pretest, 95% immediate, 86% delayed; P<0.001), and to call 911 for stroke (78% pretest, 99.8% immediate, 98% delayed; P<0.001). FAST stroke symptoms (facial droop and slurred speech) were better retained than non-FAST symptoms (headache and blurred vision) at 3 months (P<0.001). For stroke prevention measures, dietary change and exercise were better learned than concepts of diabetes, hypertension, and cholesterol. Elementary school children are educable about stroke, retain their knowledge well, and may be able to appropriately activate emergency services for acute stroke. Incorporating cultural elements such as hip-hop music may improve retention of stroke knowledge among the youth.

More outcomes than trials: a call for consistent data collection across stroke rehabilitation trials.

PubMed

Ali, M; English, C; Bernhardt, J; Sunnerhagen, K S; Brady, M

2013-01-01

Stroke survivors experience complex combinations of impairments, activity limitations, and participation restrictions. The essential components of stroke rehabilitation remain elusive. Determining efficacy in randomized controlled trials (RCTs) is challenging; there is no commonly agreed primary outcome measure for rehabilitation trials. Clinical guidelines depend on proof of efficacy in RCTs and meta-analyses. However, diverse trial aims, differing methods, inconsistent data collection, and use of multiple assessment tools hinder comparability across trials. Consistent data collection in acute stroke trials has facilitated meta-analyses to inform trial design and clinical practice. With few exceptions, inconsistent data collection has hindered similar progress in stroke rehabilitation research. There is an urgent need for the routine collection of a core dataset of common variables in rehabilitation trials. The European Stroke Organisation Outcomes Working Group, the National Institutes of Neurological Disorders and Stroke Common Data Elements project, and the Collaborative Stroke Audit and Research project have called for consistency in data collection in stroke trials. Standardizing data collection can decrease study start up times, facilitate data sharing, and inform clinical guidelines. Although achieving consensus on which outcome measures to use in stroke rehabilitation trials is a considerable task, perhaps a feasible starting point is to achieve consistency in the collection of data on demography, stroke severity, and stroke onset to inclusion times. Longer term goals could include the development of a consensus process to establish the core dataset. This should be endorsed by researchers, funders, and journal editors in order to facilitate sustainable change. © 2012 The Authors. International Journal of Stroke © 2012 World Stroke Organization.

Trace Element Cycling in Lithogenic Particles at Station ALOHA

NASA Astrophysics Data System (ADS)

Morton, P. L.; Weisend, R.; Landing, W. M.; Fitzsimmons, J. N.; Hayes, C. T.; Boyle, E. A.

2014-12-01

Trace element cycling in marine particles is influenced by atmospheric deposition, vertical export, biological uptake and remineralization, scavenging, and lateral transport processes. To investigate the cycling of lithogenic particles in the central North Pacific Ocean, surface and vertical profile samples of marine suspended particulate matter (SPM) were collected July-August 2012 during the HOE-DYLAN cruises at Station ALOHA. In the late summer, atmospheric dust inputs from the Gobi desert (which peak during the spring, April-May) were sparse, as indicated by low surface particulate Ti (pTi) concentrations. In contrast, surface pAl concentrations did not follow pTi trends as expected, but appear to be dominated by scavenging/uptake of dissolved Al during diatom blooms. Surface pMn concentrations were low, but vertical profiles of pMn and pMn/pTi reveal a strong sedimentary source at 200 m, originating from the Hawaiian continental shelf through a combination of redox mobilization and resuspension processes. The redox active elements Ce and Co can have chemistries similar to that of Mn, but in these samples the pCe and pCo distributions were distinct from Mn and each other in both surface trends and vertical profiles. Surface pREE (e.g., La, Ce, Pr) were highest during the earliest sampling events and quickly decreased to consistently low concentrations, while vertical distributions were characterized by scavenging onto biotic particles and mid-depth inputs. The surface particulate Co trend is similar to those of pAl and pP, while the pCo vertical profiles reflect surface enrichment but low concentrations and little variability at depth. A second, complementary poster is also being presented which examines the biological influence over particulate trace element cycling (Weisend et al., "Particulate Trace Element Cycling in a Diatom Bloom at Station ALOHA").

Damper mechanism for nuclear reactor control elements

DOEpatents

Taft, William Elwood

1976-01-01

A damper mechanism which provides a nuclear reactor control element decelerating function at the end of the scram stroke. The total damping function is produced by the combination of two assemblies, which operate in sequence. First, a tapered dashram assembly decelerates the control element to a lower velocity, after which a spring hydraulic damper assembly takes over to complete the final damping.

Numerical analysis of the cylindrical rigidity of the vertical steel tank shell

NASA Astrophysics Data System (ADS)

Chirkov, Sergey; Tarasenko, Alexander; Chepur, Petr

2017-10-01

The paper deals with the study of rigidity of a vertical steel cylindrical tank and its structural elements with the development of inhomogeneous subsidence in ANSYS software complex. The limiting case is considered in this paper: a complete absence of a base sector that varies along an arc of a circle. The subsidence zone is modeled by the parameter n. A finite-element model of vertical 20000 m3 steel tank has been created, taking into account all structural elements of tank metal structures, including the support ring, beam frame and roof sheets. Various combinations of vertical steel tank loading are analyzed. For operational loads, the most unfavorable combination is considered. Calculations were performed for the filled and emptied tank. Values of the maximum possible deformations of the outer contour of the bottom are obtained with the development of inhomogeneous base subsidence for the given tank size. The obtained parameters of intrinsic rigidity (deformability) of vertical steel tank can be used in the development of new regulatory and technical documentation for tanks.

Mechanical energy absorber

NASA Technical Reports Server (NTRS)

Wesselski, Clarence J. (Inventor)

1993-01-01

An energy absorbing system for controlling the force where a moving object engages a stationary stop and where the system utilized telescopic tubular members, energy absorbing diaphragm elements, force regulating disc springs, and a return spring to return the telescoping member to its start position after stroking is presented. The energy absorbing system has frusto-conical diaphragm elements frictionally engaging the shaft and are opposed by a force regulating set of disc springs. In principle, this force feedback mechanism serves to keep the stroking load at a reasonable level even if the friction coefficient increases greatly. This force feedback device also serves to desensitize the singular and combined effects of manufacturing tolerances, sliding surface wear, temperature changes, dynamic effects, and lubricity.

Emergency medical service in the stroke chain of survival.

PubMed

Chenaitia, Hichem; Lefevre, Oriane; Ho, Vanessa; Squarcioni, Christian; Pradel, Vincent; Fournier, Marc; Toesca, Richard; Michelet, Pierre; Auffray, Jean Pierre

2013-02-01

The Emergency Medical Services (EMS) play a primordial role in the early management of adults with acute ischaemic stroke (AIS). The aim of this study was to evaluate the role and effectiveness of the EMS in the stroke chain of survival in Marseille. A retrospective observational study was conducted in patients treated for AIS or transient ischaemic attack in three emergency departments and at the Marseille stroke centre over a period of 12 months. In 2009, of 1034 patients ultimately presenting a diagnosis of AIS or transient ischaemic attack, 74% benefited from EMS activation. Dispatchers correctly diagnosed 57% of stroke patients. The symptoms most frequently reported included limb weakness, speech problems and facial paresis. Elements resulting in misdiagnosis by dispatchers were general discomfort, chest pain, dyspnoea, fall or vertigo. Stroke patients not diagnosed by emergency medical dispatchers but calling within 3 h of symptom onset accounted for 20% of cases. Our study demonstrates that public intervention programmes must stress the urgency of recognizing stroke symptoms and the importance of calling EMS through free telephone numbers. Further efforts are necessary to disseminate guidelines for healthcare providers concerning stroke recognition and the new therapeutic possibilities in order to increase the likelihood of acute stroke patients presenting to a stroke team early enough to be eligible for acute treatment. In addition, EMS dispatchers should receive further training about atypical stroke symptoms, and 'Face Arm Speech Test' tests must be included in the routine questionnaires used in emergency medical calls concerning elderly persons.

Numerical investigation of thermal and residual stress of sapphire during c-axis vertical Bridgman growth process considering the solidification history effect

NASA Astrophysics Data System (ADS)

Hwang, Ji Hoon; Lee, Young Cheol; Lee, Wook Jin

2018-01-01

Sapphire single crystals have been highlighted for epitaxial of gallium nitride films in high-power laser and light emitting diode industries. In this study, the evolution of thermally induced stress in sapphire during the vertical Bridgman crystal growth process was investigated using a finite element model that simplified the real Bridgman process. A vertical Bridgman process of cylindrical sapphire crystal with a diameter of 50 mm was considered for the model. The solidification history effect during the growth was modeled by the quite element technique. The effects of temperature gradient, seeding interface shape and seeding position on the thermal stress during the process were discussed based on the finite element analysis results.

Abundance stratification in the atmospheres of blue horizontal-branch stars

NASA Astrophysics Data System (ADS)

LeBlanc, F.

2013-12-01

Horizontal-branch stars with effective temperatures larger than approximately 11 500 K show abundance anomalies as well as other peculiar observational properties believed to be due to atomic diffusion in their atmosphere. These stars possess low rotational velocities that makes it possible for atomic diffusion to come into play and are therefore of great interest with respect to diffusion theory. Observational anomalies of blue horizontal-branch stars found in globular clusters such as photometric jumps and gaps are reviewed. Recent detections of vertical stratification of elements are also discussed. These results are compared to predictions of atmospheric modeling while including vertical stratification of the elements. The atmospheric structure of these models is calculated self-consistently while taking into account vertical stratification of the elements.

Bearing capacity and rigidity of short plastic-concrete-tubal vertical columns under transverse load

NASA Astrophysics Data System (ADS)

Dolzhenko, A. V.; Naumov, A. E.; Shevchenko, A. E.

2018-03-01

The results of mathematical modeling in determining strain-stress distribution parameters of a short plastic-concrete-tubal vertical column under horizontal load as those in vertical constructions are described. Quantitative parameters of strain-stress distribution during vertical and horizontal loads and horizontal stiffness were determined by finite element modeling. The internal stress in the concrete column core was analyzed according to equivalent stress in Mohr theory of failure. It was determined that the bearing capacity of a short plastic- concrete-tubal vertical column is 25% higher in resistibility and 15% higher in rigidness than those of the caseless concrete columns equal in size. Cracks formation in the core of a short plastic-concrete-tubal vertical column happens under significantly bigger horizontal loads with less amount of concrete spent than that in caseless concrete columns. The significant increase of bearing capacity and cracking resistance of a short plastic-concrete-tubal vertical column under vertical and horizontal loads allows recommending them as highly effective and highly reliable structural wall elements in civil engineering.

Comparison of stroke warning sign campaigns in Australia, England, and Canada.

PubMed

Trobbiani, Kym; Freeman, Kate; Arango, Manuel; Lalor, Erin; Jenkinson, Damian; Thrift, Amanda G

2013-10-01

Public awareness of the signs of stroke is essential to ensure that those affected by stroke arrive at the hospital in time for lifesaving therapies. It is unclear how well stroke awareness campaigns improve awareness of stroke signs and whether people translate this into action. We evaluated stroke awareness campaigns conducted in England, Australia, and Canada using pre- and post-campaign surveys. We assessed the proportion of people who could name the main signs of stroke, and compared the proportion naming these correctly between locations. We also assessed whether people would call emergency services in the event of a stroke. Proportion responding correctly was compared using chi-square analysis. The amount spent on the campaigns was different in each country. The post-campaign survey was conducted among 400 people in Australia, 1921 in England, and 2703 in Canada. Sixty-eight per cent of people in Australia and 57% in Canada could name two or more signs of stroke (P < 0.001). After the campaign, knowledge of each of the elements of the campaign (face, arm, speech, time) was significantly greater in England than in Australia (P < 0.001 for each item). A high proportion of participants reported that they would call emergency services in the event of a stroke (97% in England, 90% in Australia, and 67% in Canada). Knowledge of stroke signs and the action to be taken can be improved with awareness campaigns. The effectiveness of these campaigns may be enhanced by spend on media, media mix, and key messages. It is critical to ensure that campaigns provide the clear and bold message that prompt action is an essential ingredient to reduce death and disability following stroke. © 2012 The Authors. International Journal of Stroke © 2012 World Stroke Organization.

Beam steering via resonance detuning in coherently coupled vertical cavity laser arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Matthew T., E-mail: matthew.johnson.9@us.af.mil; Siriani, Dominic F.; Peun Tan, Meng

2013-11-11

Coherently coupled vertical-cavity surface-emitting laser arrays offer unique advantages for nonmechanical beam steering applications. We have applied dynamic coupled mode theory to show that the observed temporal phase shift between vertical-cavity surface-emitting array elements is caused by the detuning of their resonant wavelengths. Hence, a complete theoretical connection between the differential current injection into array elements and the beam steering direction has been established. It is found to be a fundamentally unique beam-steering mechanism with distinct advantages in efficiency, compactness, speed, and phase-sensitivity to current.

Corrugated paraffin nanocomposite films as large stroke thermal actuators and self-activating thermal interfaces.

PubMed

Copic, Davor; Hart, A John

2015-04-22

High performance active materials are of rapidly growing interest for applications including soft robotics, microfluidic systems, and morphing composites. In particular, paraffin wax has been used to actuate miniature pumps, solenoid valves, and composite fibers, yet its deployment is typically limited by the need for external volume constraint. We demonstrate that compact, high-performance paraffin actuators can be made by confining paraffin within vertically aligned carbon nanotube (CNT) films. This large-stroke vertical actuation is enabled by strong capillary interaction between paraffin and CNTs and by engineering the CNT morphology by mechanical compression before capillary-driven infiltration of the molten paraffin. The maximum actuation strain of the corrugated CNT-paraffin films (∼0.02-0.2) is comparable to natural muscle, yet the maximum stress is limited to ∼10 kPa by collapse of the CNT network. We also show how a CNT-paraffin film can serve as a self-activating thermal interface that closes a gap when it is heated. These new CNT-paraffin film actuators could be produced by large-area CNT growth, infiltration, and lamination methods, and are attractive for use in miniature systems due to their self-contained design.

FDTD Modeling of LEMP Propagation in the Earth-Ionosphere Waveguide With Emphasis on Realistic Representation of Lightning Source

NASA Astrophysics Data System (ADS)

Tran, Thang H.; Baba, Yoshihiro; Somu, Vijaya B.; Rakov, Vladimir A.

2017-12-01

The finite difference time domain (FDTD) method in the 2-D cylindrical coordinate system was used to compute the nearly full-frequency-bandwidth vertical electric field and azimuthal magnetic field waveforms produced on the ground surface by lightning return strokes. The lightning source was represented by the modified transmission-line model with linear current decay with height, which was implemented in the FDTD computations as an appropriate vertical phased-current-source array. The conductivity of atmosphere was assumed to increase exponentially with height, with different conductivity profiles being used for daytime and nighttime conditions. The fields were computed at distances ranging from 50 to 500 km. Sky waves (reflections from the ionosphere) were identified in computed waveforms and used for estimation of apparent ionospheric reflection heights. It was found that our model reproduces reasonably well the daytime electric field waveforms measured at different distances and simulated (using a more sophisticated propagation model) by Qin et al. (2017). Sensitivity of model predictions to changes in the parameters of atmospheric conductivity profile, as well as influences of the lightning source characteristics (current waveshape parameters, return-stroke speed, and channel length) and ground conductivity were examined.

Effect of air-entry angle on performance of a 2-stroke-cycle compression-ignition engine

NASA Technical Reports Server (NTRS)

Earle, Sherod L; Dutee, Francis J

1937-01-01

An investigation was made to determine the effect of variations in the horizontal and vertical air-entry angles on the performance characteristics of a single-cylinder 2-stroke-cycle compression-ignition test engine. Performance data were obtained over a wide range of engine speed, scavenging pressure, fuel quantity, and injection advance angle with the optimum guide vanes. Friction and blower-power curves are included for calculating the indicated and net performances. The optimum horizontal air-entry angle was found to be 60 degrees from the radial and the optimum vertical angle to be zero, under which conditions a maximum power output of 77 gross brake horsepower for a specific fuel consumption of 0.52 pound per brake horsepower-hour was obtained at 1,800 r.p.m. and 16-1/2 inches of Hg scavenging pressure. The corresponding specific output was 0.65 gross brake horsepower per cubic inch of piston displacement. Tests revealed that the optimum scavenging pressure increased linearly with engine speed. The brake mean effective pressure increased uniformly with air quantity per cycle for any given vane angle and was independent of engine speed and scavenging pressure.

First images of thunder: Acoustic imaging of triggered lightning

NASA Astrophysics Data System (ADS)

Dayeh, M. A.; Evans, N. D.; Fuselier, S. A.; Trevino, J.; Ramaekers, J.; Dwyer, J. R.; Lucia, R.; Rassoul, H. K.; Kotovsky, D. A.; Jordan, D. M.; Uman, M. A.

2015-07-01

An acoustic camera comprising a linear microphone array is used to image the thunder signature of triggered lightning. Measurements were taken at the International Center for Lightning Research and Testing in Camp Blanding, FL, during the summer of 2014. The array was positioned in an end-fire orientation thus enabling the peak acoustic reception pattern to be steered vertically with a frequency-dependent spatial resolution. On 14 July 2014, a lightning event with nine return strokes was successfully triggered. We present the first acoustic images of individual return strokes at high frequencies (>1 kHz) and compare the acoustically inferred profile with optical images. We find (i) a strong correlation between the return stroke peak current and the radiated acoustic pressure and (ii) an acoustic signature from an M component current pulse with an unusual fast rise time. These results show that acoustic imaging enables clear identification and quantification of thunder sources as a function of lightning channel altitude.

Posterior insular cortex - a site of vestibular-somatosensory interaction?

PubMed

Baier, Bernhard; Zu Eulenburg, Peter; Best, Christoph; Geber, Christian; Müller-Forell, Wibke; Birklein, Frank; Dieterich, Marianne

2013-09-01

Background In previous imaging studies the insular cortex (IC) has been identified as an essential part of the processing of a wide spectrum of perception and sensorimotor integration. Yet, there are no systematic lesion studies in a sufficient number of patients examining whether processing of vestibular and the interaction of somatosensory and vestibular signals take place in the IC. Methods We investigated acute stroke patients with lesions affecting the IC in order to fill this gap. In detail, we explored signs of a vestibular tone imbalance such as the deviation of the subjective visual vertical (SVV). We applied voxel-lesion behaviour mapping analysis in 27 patients with acute unilateral stroke. Results Our data demonstrate that patients with lesions of the posterior IC have an abnormal tilt of SVV. Furthermore, re-analysing data of 20 patients from a previous study, we found a positive correlation between thermal perception contralateral to the stroke and the severity of the SVV tilt. Conclusions We conclude that the IC is a sensory brain region where different modalities might interact.

["Healthy Region Lower Rhine ... against Stroke": the concept and implementation of an intersectoral public health programme 2003-2008].

PubMed

Rau, Rüdiger; Rumpeltin, Carsten; Hoop, Renate; Pfeiffer, Holger; Drees, Jeannette; Paas, Birgit; Schmitz-Buhl, Gabriele; Geraedts, Max

2009-01-01

When the Public Health Service Act of North Rhine-Westphalia (OGDG-NRW) came into effect local health conferences (KGK) were established in both rural and urban districts. These conferences are designed to optimize medical and social healthcare at the local level. In 2001 KGK managers from six neighbouring districts founded the Network Healthy Lower Rhine. From 2003 to 2008 this network was able to implement the "Healthy Lower Rhine ... against Stroke" programme. The initiative primarily aims at improving community knowledge of stroke with regard to 1) proper action ("Stroke is a medical emergency, so call the emergency number 112!") and 2) stroke warning signs. Eventually these steps are intended 3) to reduce prehospital delays. Before the program started a project plan was developed including evaluation approaches. The central elements of the concept include local health targets, intersectoral collaboration and networking, 5-year programme duration, social marketing and a communication strategy. Initially, a needs assessment was conducted using local expert panels, surveys on community knowledge, and clinical data sampling to assess healthcare quality. Subsequently, a package of measures with a "two-level implementation model" was prepared. Normative evaluation consisted of self-reflection within the network-team. The summative evaluation was based on two approaches: surveys on community knowledge of stroke (city of Düsseldorf and district of Wesel) as well as data sample collection in hospitals on health care quality. The central elements of the concepts were implemented. Community surveys revealed similar deficits in community knowledge of stroke in the city of Dusseldorf (2000 and 2004) and in the district of Wesel (2002 and 2008). Knowledge of proper action (call 112 in case of stroke) significantly improved in the Dusseldorf community from 32.5% of correct statements in 2000 to 50.6% correct answers in 2004 and, finally, in 2008 to 69% correct answers in the Wesel district. Hospitals in the district of Wesel collected three-month samples of data on prehospital times in 2003 (before the initiative was started) and in 2005. There was no significant change: the portion of 28% of patients being hospitalized within a three-hour window after the onset of stroke symptoms remained unchanged. Due to medical progress and demographic changes stroke remains a paramount issue of public health in Germany. With its programme "Healthy Lower Rhine ... against Stroke" the Network Healthy Lower Rhine provides a strategy for launching and implementing a complex and intersectoral public health intervention.

Third European Stroke Science Workshop.

PubMed

Dichgans, Martin; Planas, Anna M; Biessels, Geert Jan; van der Worp, Bart; Sudlow, Cathie; Norrving, Bo; Lees, Kennedy; Mattle, Heinrich P

2016-07-01

Lake Eibsee, Garmisch-Partenkirchen, November 19 to 21, 2015: The European Stroke Organization convened >120 stroke experts from 27 countries to discuss latest results and hot topics in clinical, translational, and basic stroke research. Since its inception in 2011, the European Stroke Science Workshop has become a cornerstone of European Stroke Organization's academic activities and major highlight for researchers in the field. Participants include stroke researchers at all career stages who convene for plenary lectures and discussions, thus facilitating crosstalk among researchers from different fields. As in previous years, the workshop was organized into 7 scientific sessions each focusing on a major research topic. All sessions started with a keynote lecture that provided an overview on current developments and set the scene for the following presentations. The latter were short focused talks on a timely topic and included the most recent findings, including unpublished data. A new element at this year's meeting was a hot topic session in which speakers had to present a provocative concept or update sharply within 5 minutes. In the following, we summarize the key contents of the meeting. The program is provided in the online-only Data Supplement. © 2016 American Heart Association, Inc.

Flipper stroke rate and venous oxygen levels in free-ranging California sea lions.

PubMed

Tift, Michael S; Hückstädt, Luis A; McDonald, Birgitte I; Thorson, Philip H; Ponganis, Paul J

2017-04-15

The depletion rate of the blood oxygen store, development of hypoxemia and dive capacity are dependent on the distribution and rate of blood oxygen delivery to tissues while diving. Although blood oxygen extraction by working muscle would increase the blood oxygen depletion rate in a swimming animal, there is little information on the relationship between muscle workload and blood oxygen depletion during dives. Therefore, we examined flipper stroke rate, a proxy of muscle workload, and posterior vena cava oxygen profiles in four adult female California sea lions ( Zalophus californianus ) during foraging trips at sea. Flipper stroke rate analysis revealed that sea lions minimized muscle metabolism with a stroke-glide strategy when diving, and exhibited prolonged glides during the descent of deeper dives (>100 m). During the descent phase of these deep dives, 55±21% of descent was spent gliding, with the longest glides lasting over 160 s and covering a vertical distance of 340 m. Animals also consistently glided to the surface from 15 to 25 m depth during these deeper dives. Venous hemoglobin saturation ( S O 2 ) profiles were highly variable throughout dives, with values occasionally increasing during shallow dives. The relationship between S O 2 and flipper stroke rate was weak during deeper dives, while this relationship was stronger during shallow dives. We conclude that (1) the depletion of oxygen in the posterior vena cava in deep-diving sea lions is not dependent on stroke effort, and (2) stroke-glide patterns during dives contribute to a reduction of muscle metabolic rate. © 2017. Published by The Company of Biologists Ltd.

PSD-95 is required to sustain the molecular organization of the postsynaptic density

PubMed Central

Chen, Xiaobing; Nelson, Christopher D; Li, Xiang; Winters, Christine A.; Azzam, Rita; Sousa, Alioscka A.; Leapman, Richard D.; Gainer, Harold; Sheng, Morgan; Reese, Thomas S.

2011-01-01

PSD-95, a membrane-associated guanylate kinase (MAGUK), is the major scaffolding protein in the excitatory postsynaptic density (PSD) and a potent regulator of synaptic strength. Here we show that PSD-95 is in an extended configuration and positioned into regular arrays of vertical filaments that contact both glutamate receptors and orthogonal horizontal elements layered deep inside the PSD in rat hippocampal spine synapses. RNAi knockdown of PSD-95 leads to loss of entire patches of PSD material, and EM tomography shows that the patchy loss correlates with loss of PSD-95-containing vertical filaments, horizontal elements associated with the vertical filaments, and putative AMPA, but not NMDA receptor type structures. These observations show that the orthogonal molecular scaffold constructed from PSD-95-containing vertical filaments and their associated horizontal elements is essential for sustaining the three dimensional molecular organization of the PSD. Our findings provide a structural basis for understanding the functional role of PSD-95 at the PSD. PMID:21525273

Scavenging flow velocity in small two-strokes at high engine speed

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ekenberg, M.; Johansson, B.

1995-12-31

2D-LDV-measurements were made on the flow from one transfer channel into the cylinder in a small two-stroke SI engine. The LDV measuring volume was located just outside the transfer port. The engine was a carburetted piston-ported crankcase compression chainsaw engine and it was run with wide open throttle at 9000 RPM. The muffler was removed to enable access into the cylinder. No additional seeding was used; the fuel and/or oil was not entirely vaporized as it entered the cylinder. Very high velocities ({approximately}275 m/s) were detected in the beginning of the scavenging phase. The horizontal velocity was, during the wholemore » scavenging phase, higher than the vertical.« less

Differentiating the effects of characteristics of PM pollution on mortality from ischemic and hemorrhagic strokes.

PubMed

Lin, Hualiang; Tao, Jun; Du, Yaodong; Liu, Tao; Qian, Zhengmin; Tian, Linwei; Di, Qian; Zeng, Weilin; Xiao, Jianpeng; Guo, Lingchuan; Li, Xing; Xu, Yanjun; Ma, Wenjun

2016-03-01

Though increasing evidence supports significant association between particulate matter (PM) air pollution and stroke, it remains unclear what characteristics, such as particle size and chemical constituents, are responsible for this association. A time-series model with quasi-Poisson function was applied to assess the association of PM pollution with different particle sizes and chemical constituents with mortalities from ischemic and hemorrhagic strokes in Guangzhou, China, we controlled for potential confounding factors in the model, such as temporal trends, day of the week, public holidays, meteorological factors and influenza epidemic. We found significant association between stroke mortality and various PM fractions, such as PM10, PM2.5 and PM1, with generally larger magnitudes for smaller particles. For the PM2.5 chemical constituents, we found that organic carbon (OC), elemental carbon (EC), sulfate, nitrate and ammonium were significantly associated with stroke mortality. The analysis for specific types of stroke suggested that it was hemorrhagic stroke, rather than ischemic stroke, that was significantly associated with PM pollution. Our study shows that various PM pollution fractions are associated with stroke mortality, and constituents primarily from combustion and secondary aerosols might be the harmful components of PM2.5 in Guangzhou, and this study suggests that PM pollution is more relevant to hemorrhagic stroke in the study area, however, more studies are warranted due to the underlying limitations of this study. Copyright © 2015 Elsevier GmbH. All rights reserved.

Enclosed, off-axis solar concentrator

DOEpatents

Benitez, Pablo; Grip, Robert E; Minano, Juan C; Narayanan, Authi A; Plesniak, Adam; Schwartz, Joel A

2013-11-26

A solar concentrator including a housing having receiving wall, a reflecting wall and at least two end walls, the receiving, reflecting and end walls defining a three-dimensional volume having an inlet, wherein a vertical axis of the housing is generally perpendicular to the inlet, a receiver mounted on the receiving wall of the housing, the receiver including at least one photovoltaic cell, wherein a vertical axis of the receiver is disposed at a non-zero angle relative to the vertical axis of the housing, at least one clip disposed on the reflecting wall an optical element received within the three-dimensional volume, the optical element including at least one tab, the tab being engaged by the clip to align the optical element with the receiver, and a window received over the inlet to enclose the housing.

PHARYNGEAL SWALLOWING MECHANICS SECONDARY TO HEMISPHERIC STROKE

PubMed Central

May, Nelson H; Pisegna, Jessica M; Marchina, Sarah; Langmore, Susan E; Kumar, Sandeep; Pearson, William G

2016-01-01

Goals Computational Analysis of Swallowing Mechanics is a method that utilizes multivariate shape change analysis to uncover covariant elements of pharyngeal swallowing mechanics associated with impairment using videofluoroscopic swallowing studies. The goals of this preliminary study were to (1) characterize swallowing mechanics underlying stroke related dysphagia, (2) decipher the impact of left and right hemispheric stroke on pharyngeal swallowing mechanics, and (3) determine pharyngeal swallowing mechanics associated with penetration-aspiration status. Materials and Methods Videofluoroscopic swallowing studies of 18 dysphagic patients with hemispheric infarcts and age and gender matched controls were selected from well-controlled data sets. Patient data including laterality, and penetration-aspiration status was collected. Coordinates mapping muscle group action during swallowing were collected from videos. Multivariate morphometric analyses of coordinates associated with stroke, affected hemisphere, and penetration-aspiration status were performed. Findings Pharyngeal swallowing mechanics differed significantly in the following comparisons: stroke vs. controls (D=2.19, p<.0001); right hemispheric stroke vs. controls (D=3.64, p<.0001); left hemispheric stroke vs. controls (D=2.06, p<.0001); right hemispheric stroke vs. left hemispheric stroke (D=2.89, p<.0001); and penetration-aspiration vs. within normal limits (D=2.25, p<.0001). Differences in pharyngeal swallowing mechanics associated with each comparison were visualized using eigenvectors. Conclusion While current literature focuses on timing changes in stroke-related dysphagia, this data suggests that mechanical changes are also functionally important. Pharyngeal swallowing mechanics differed by affected hemisphere and penetration-aspiration status. Computational Analysis of Swallowing Mechanics can be used to identify patient specific swallowing impairment associated with stroke injury that could help guide rehabilitation strategies to improve swallowing outcomes. PMID:27913200

Genetic Architecture of Lacunar Stroke.

PubMed

Traylor, Matthew; Bevan, Steve; Baron, Jean-Claude; Hassan, Ahamad; Lewis, Cathryn M; Markus, Hugh S

2015-09-01

Lacunar strokes comprise ≈20% of all strokes. Despite this frequency, their pathogenesis is poorly understood. Previous genome-wide association studies in lacunar stroke have been disappointing, which may be because of phenotypic heterogeneity. Pathological and radiological studies suggest that there may be different pathologies underlying lacunar strokes. This has led to the suggestion of 2 subtypes: isolated lacunar infarcts and multiple lacunar infarcts and leukoaraiosis. We performed genome-wide analyses in a magnetic resonance imaging-verified cohort of 1012 younger onset lacunar stroke cases and 964 controls. Using these data, we first estimated the heritability of lacunar stroke and its 2 hypothesized subtypes, and secondly, we determined whether this is enriched for regulatory regions in the genome, as defined by data from Encyclopedia of DNA Elements (ENCODE) and other sources. Finally, we determine the evidence for a polygenic contribution from rare variation to lacunar stroke and its subtypes. Our results indicate a substantial heritable component to magnetic resonance imaging-verified lacunar stroke (20%-25%) and its 2 subtypes (isolated lacunar infarct, 15%-18%; multiple lacunar infarcts/leukoaraiosis, 23%-28%). This heritable component is significantly enriched for sites affecting expression of genes. In addition, we show that the risk of the 2 subtypes of lacunar stroke in isolation, but not in combination, is associated with rare variation in the genome. Lacunar stroke, when defined on magnetic resonance imaging, is a highly heritable complex disease. Much of this heritability arises from regions of the genome affecting gene regulation. Rare variation affects 2 subtypes of lacunar in isolation, suggesting that they may have distinct genetic susceptibility factors. © 2015 The Authors.

e-NIHSS: an Expanded National Institutes of Health Stroke Scale Weighted for Anterior and Posterior Circulation Strokes.

PubMed

Olivato, Silvia; Nizzoli, Silvia; Cavazzuti, Milena; Casoni, Federica; Nichelli, Paolo Frigio; Zini, Andrea

2016-12-01

The National Institutes of Health Stroke Scale (NIHSS) is the most widespread clinical scale used in patients presenting with acute stroke. The merits of the NIHSS include simplicity, quickness, and agreement between clinicians. The clinical evaluation on posterior circulation stroke remains still a limit of NIHSS. We assessed the application of a new version of NIHSS, the e-NIHSS (expanded NIHSS), adding specific elements in existing items to explore signs/symptoms of a posterior circulation stroke. A total of 22 consecutive patients with suspected vertebrobasilar stroke were compared with 25 patients with anterior circulation stroke using NIHSS and e-NIHSS. We compared the NIHSS and e-NIHSS scores obtained by the 2 examiners, in patients with posterior circulation infarct (POCI), using the Wilcoxon test. Patients with POCI evaluated with e-NIHSS had an average of 2 points higher than patients evaluated with classical NIHSS. The difference was statistically significant (P < .05), weighted by the new expanded items. The NIHSS is a practical scale model, with high reproducibility between trained, different examiners, focused on posterior circulation strokes, with the same total score and number of items of the existing NIHSS. The e-NHISS could improve the sensitivity of NIHSS in posterior circulation stroke and could have an impact on clinical trials, as well as on outcomes. Further studies are needed to investigate a larger number of patients and the correlation between the e-NIHSS score and neuroimaging findings. Copyright © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Exploratory study on the methodology of fast imaging of unilateral stroke lesions by electrical impedance asymmetry in human heads.

PubMed

Ma, Jieshi; Xu, Canhua; Dai, Meng; You, Fusheng; Shi, Xuetao; Dong, Xiuzhen; Fu, Feng

2014-01-01

Stroke has a high mortality and disability rate and should be rapidly diagnosed to improve prognosis. Diagnosing stroke is not a problem for hospitals with CT, MRI, and other imaging devices but is difficult for community hospitals without these devices. Based on the mechanism that the electrical impedance of the two hemispheres of a normal human head is basically symmetrical and a stroke can alter this symmetry, a fast electrical impedance imaging method called symmetrical electrical impedance tomography (SEIT) is proposed. In this technique, electrical impedance tomography (EIT) data measured from the undamaged craniocerebral hemisphere (CCH) is regarded as reference data for the remaining EIT data measured from the other CCH for difference imaging to identify the differences in resistivity distribution between the two CCHs. The results of SEIT imaging based on simulation data from the 2D human head finite element model and that from the physical phantom of human head verified this method in detection of unilateral stroke.

Exploratory Study on the Methodology of Fast Imaging of Unilateral Stroke Lesions by Electrical Impedance Asymmetry in Human Heads

PubMed Central

Xu, Canhua; Dai, Meng; You, Fusheng; Shi, Xuetao

2014-01-01

Stroke has a high mortality and disability rate and should be rapidly diagnosed to improve prognosis. Diagnosing stroke is not a problem for hospitals with CT, MRI, and other imaging devices but is difficult for community hospitals without these devices. Based on the mechanism that the electrical impedance of the two hemispheres of a normal human head is basically symmetrical and a stroke can alter this symmetry, a fast electrical impedance imaging method called symmetrical electrical impedance tomography (SEIT) is proposed. In this technique, electrical impedance tomography (EIT) data measured from the undamaged craniocerebral hemisphere (CCH) is regarded as reference data for the remaining EIT data measured from the other CCH for difference imaging to identify the differences in resistivity distribution between the two CCHs. The results of SEIT imaging based on simulation data from the 2D human head finite element model and that from the physical phantom of human head verified this method in detection of unilateral stroke. PMID:25006594

Pharyngeal Swallowing Mechanics Secondary to Hemispheric Stroke.

PubMed

May, Nelson H; Pisegna, Jessica M; Marchina, Sarah; Langmore, Susan E; Kumar, Sandeep; Pearson, William G

2017-05-01

Computational analysis of swallowing mechanics (CASM) is a method that utilizes multivariate shape change analysis to uncover covariant elements of pharyngeal swallowing mechanics associated with impairment using videofluoroscopic swallowing studies. The goals of this preliminary study were to (1) characterize swallowing mechanics underlying stroke-related dysphagia, (2) decipher the impact of left and right hemispheric strokes on pharyngeal swallowing mechanics, and (3) determine pharyngeal swallowing mechanics associated with penetration-aspiration status. Videofluoroscopic swallowing studies of 18 dysphagic patients with hemispheric infarcts and age- and gender-matched controls were selected from well-controlled data sets. Patient data including laterality and penetration-aspiration status were collected. Coordinates mapping muscle group action during swallowing were collected from videos. Multivariate morphometric analyses of coordinates associated with stroke, affected hemisphere, and penetration-aspiration status were performed. Pharyngeal swallowing mechanics differed significantly in the following comparisons: stroke versus controls (D = 2.19, P < .0001), right hemispheric stroke versus controls (D = 3.64, P < .0001), left hemispheric stroke versus controls (D = 2.06, P < .0001), right hemispheric stroke versus left hemispheric stroke (D = 2.89, P < .0001), and penetration-aspiration versus within normal limits (D = 2.25, P < .0001). Differences in pharyngeal swallowing mechanics associated with each comparison were visualized using eigenvectors. Whereas current literature focuses on timing changes in stroke-related dysphagia, these data suggest that mechanical changes are also functionally important. Pharyngeal swallowing mechanics differed by the affected hemisphere and the penetration-aspiration status. CASM can be used to identify patient-specific swallowing impairment associated with stroke injury that could help guide rehabilitation strategies to improve swallowing outcomes. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Effects of Selected Filmic Coding Elements of TV on the Development of the Euclidean Concepts of Horizontality and Verticality in Adolescents.

ERIC Educational Resources Information Center

Lynch, Beth Eloise

This study was conducted to determine whether the filmic coding elements of split screen, slow motion, generated line cues, the zoom of a camera, and rotation could aid in the development of the Euclidean space concepts of horizontality and verticality, and to explore presence and development of spatial skills involving these two concepts in…

Finite element probabilistic risk assessment of transmission line insulation flashovers caused by lightning strokes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bacvarov, D.C.

1981-01-01

A new method for probabilistic risk assessment of transmission line insulation flashovers caused by lightning strokes is presented. The utilized approach of applying the finite element method for probabilistic risk assessment is demonstrated to be very powerful. The reasons for this are two. First, the finite element method is inherently suitable for analysis of three dimensional spaces where the parameters, such as three variate probability densities of the lightning currents, are non-uniformly distributed. Second, the finite element method permits non-uniform discretization of the three dimensional probability spaces thus yielding high accuracy in critical regions, such as the area of themore » low probability events, while at the same time maintaining coarse discretization in the non-critical areas to keep the number of grid points and the size of the problem to a manageable low level. The finite element probabilistic risk assessment method presented here is based on a new multidimensional search algorithm. It utilizes an efficient iterative technique for finite element interpolation of the transmission line insulation flashover criteria computed with an electro-magnetic transients program. Compared to other available methods the new finite element probabilistic risk assessment method is significantly more accurate and approximately two orders of magnitude computationally more efficient. The method is especially suited for accurate assessment of rare, very low probability events.« less

MARS: A protein family involved in the formation of vertical skeletal elements.

PubMed

Abehsera, Shai; Peles, Shani; Tynyakov, Jenny; Bentov, Shmuel; Aflalo, Eliahu D; Li, Shihao; Li, Fuhua; Xiang, Jianhai; Sagi, Amir

2017-05-01

Vertical organizations of skeletal elements are found in various vertebrate teeth and invertebrate exoskeletons. The molecular mechanism behind the development of such structural organizations is poorly known, although it is generally held that organic matrix proteins play an essential role. While most crustacean cuticular organizations exhibit horizontal chitinous layering, a typical vertical organization is found towards the surface of the teeth in the mandibles of the crayfish Cherax quadricarinatus. Candidate genes encoding for mandible-forming structural proteins were mined in C. quadricarinatus molt-related transcriptomic libraries by using a binary patterning approach. A new protein family, termed the Mandible Alanine Rich Structural (MARS) protein family, with a modular sequence design predicted to form fibers, was found. Investigations of spatial and temporal expression of the different MARS genes suggested specific expression in the mandibular teeth-forming epithelium, particularly during the formation of the chitinous vertical organization. MARS loss-of-function RNAi experiments resulted in the collapse of the organization of the chitin fibers oriented vertically to the surface of the crayfish mandibular incisor tooth. A general search of transcriptomic libraries suggested conservation of MARS proteins across a wide array of crustaceans. Our results provide a first look into the molecular mechanism used to build the complex crustacean mandible and into the specialized vertical structural solution that has evolved in skeletal elements. Copyright © 2017 Elsevier Inc. All rights reserved.

Stroke patients’ utilisation of extrinsic feedback from computer-based technology in the home: a multiple case study realistic evaluation

PubMed Central

2014-01-01

Background Evidence indicates that post − stroke rehabilitation improves function, independence and quality of life. A key aspect of rehabilitation is the provision of appropriate information and feedback to the learner. Advances in information and communications technology (ICT) have allowed for the development of various systems to complement stroke rehabilitation that could be used in the home setting. These systems may increase the provision of rehabilitation a stroke survivor receives and carries out, as well as providing a learning platform that facilitates long-term self-managed rehabilitation and behaviour change. This paper describes the application of an innovative evaluative methodology to explore the utilisation of feedback for post-stroke upper-limb rehabilitation in the home. Methods Using the principles of realistic evaluation, this study aimed to test and refine intervention theories by exploring the complex interactions of contexts, mechanisms and outcomes that arise from technology deployment in the home. Methods included focus groups followed by multi-method case studies (n = 5) before, during and after the use of computer-based equipment. Data were analysed in relation to the context-mechanism-outcome hypotheses case by case. This was followed by a synthesis of the findings to answer the question, ‘what works for whom and in what circumstances and respects?’ Results Data analysis reveals that to achieve desired outcomes through the use of ICT, key elements of computer feedback, such as accuracy, measurability, rewarding feedback, adaptability, and knowledge of results feedback, are required to trigger the theory-driven mechanisms underpinning the intervention. In addition, the pre-existing context and the personal and environmental contexts, such as previous experience of service delivery, personal goals, trust in the technology, and social circumstances may also enable or constrain the underpinning theory-driven mechanisms. Conclusions Findings suggest that the theory-driven mechanisms underpinning the utilisation of feedback from computer-based technology for home-based upper-limb post-stroke rehabilitation are dependent on key elements of computer feedback and the personal and environmental context. The identification of these elements may therefore inform the development of technology; therapy education and the subsequent adoption of technology and a self-management paradigm; long-term self-managed rehabilitation; and importantly, improvements in the physical and psychosocial aspects of recovery. PMID:24903401

Stroke patients' utilisation of extrinsic feedback from computer-based technology in the home: a multiple case study realistic evaluation.

PubMed

Parker, Jack; Mawson, Susan; Mountain, Gail; Nasr, Nasrin; Zheng, Huiru

2014-06-05

Evidence indicates that post-stroke rehabilitation improves function, independence and quality of life. A key aspect of rehabilitation is the provision of appropriate information and feedback to the learner.Advances in information and communications technology (ICT) have allowed for the development of various systems to complement stroke rehabilitation that could be used in the home setting. These systems may increase the provision of rehabilitation a stroke survivor receives and carries out, as well as providing a learning platform that facilitates long-term self-managed rehabilitation and behaviour change. This paper describes the application of an innovative evaluative methodology to explore the utilisation of feedback for post-stroke upper-limb rehabilitation in the home. Using the principles of realistic evaluation, this study aimed to test and refine intervention theories by exploring the complex interactions of contexts, mechanisms and outcomes that arise from technology deployment in the home. Methods included focus groups followed by multi-method case studies (n = 5) before, during and after the use of computer-based equipment. Data were analysed in relation to the context-mechanism-outcome hypotheses case by case. This was followed by a synthesis of the findings to answer the question, 'what works for whom and in what circumstances and respects?' Data analysis reveals that to achieve desired outcomes through the use of ICT, key elements of computer feedback, such as accuracy, measurability, rewarding feedback, adaptability, and knowledge of results feedback, are required to trigger the theory-driven mechanisms underpinning the intervention. In addition, the pre-existing context and the personal and environmental contexts, such as previous experience of service delivery, personal goals, trust in the technology, and social circumstances may also enable or constrain the underpinning theory-driven mechanisms. Findings suggest that the theory-driven mechanisms underpinning the utilisation of feedback from computer-based technology for home-based upper-limb post-stroke rehabilitation are dependent on key elements of computer feedback and the personal and environmental context. The identification of these elements may therefore inform the development of technology; therapy education and the subsequent adoption of technology and a self-management paradigm; long-term self-managed rehabilitation; and importantly, improvements in the physical and psychosocial aspects of recovery.

Vertical Hegelianism and Beyond: Digital Cinema Editing.

ERIC Educational Resources Information Center

Wyatt, Roger B.

Cinema as an art and communication form is entering its second century of development. Sergei Eisenstein conceived of editing in horizontal and vertical terms. He saw vertical editing patterns primarily as the synchronization of simultaneous image and sound elements, particularly music, no create cinematic meaning by means of the relationship…

Transversing the Vertical Case Study: A Methodological Approach to Studies of Educational Policy as Practice

ERIC Educational Resources Information Center

Bartlett, Lesley; Vavrus, Frances

2014-01-01

How can scholars trace the global production and circulation of educational policies? The vertical case study incorporates three elements: "vertical" attention across micro-, meso-, and macro-levels, or scales; a "horizontal" comparison of how policies unfold in distinct locations; and a "transversal," processual…

The geographic distribution of trace elements in the environment: the REGARDS study.

PubMed

Rembert, Nicole; He, Ka; Judd, Suzanne E; McClure, Leslie A

2017-02-01

Research on trace elements and the effects of their ingestion on human health is often seen in scientific literature. However, little research has been done on the distribution of trace elements in the environment and their impact on health. This paper examines what characteristics among participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study are associated with levels of environmental exposure to arsenic, magnesium, mercury, and selenium. Demographic information from REGARDS participants was combined with trace element concentration data from the US Geochemical Survey (USGS). Each trace element was characterized as either low (magnesium and selenium) or high (arsenic and mercury) exposure. Associations between demographic characteristics and trace element concentrations were analyzed with unadjusted and adjusted logistic regression models. Individuals who reside in the Stroke Belt have lower odds of high exposure (4th quartile) to arsenic (OR 0.33, CI 0.31, 0.35) and increased exposure to mercury (OR 0.65, CI 0.62, 0.70) than those living outside of these areas, while the odds of low exposure to trace element concentrations were increased for magnesium (OR 5.48, CI 5.05, 5.95) and selenium (OR 2.37, CI 2.22, 2.54). We found an association between levels of trace elements in the environment and geographic region of residence, among other factors. Future studies are needed to further examine this association and determine whether or not these differences may be related to geographic variation in disease.

Sprite Climatology in the Eastern Mediterranean Region

NASA Astrophysics Data System (ADS)

Yair, Yoav; Price, Colin; Katzenelson, Dor; Rosenthal, Neta; Rubanenko, Lior; Ben-Ami, Yuval; Arnone, Enrico

2015-04-01

We present statistical analysis of 436 sprites observed in 7 winter campaigns from 2006/7-2012/13. Results show a clear peak in the frequency of sprite detections, with maximum values (< 40% of events) between 00:30-02:15 LST (22:30-00:15 UT; LST=UT+2). The detection times of sprites are well-correlated with a relative increase in the fraction of +CG strokes, which exhibit maxima between 00:00-02:00 LST. The morphological distribution of 339 sprites, that we were able to clearly identify, is dominated by column sprites (49.3%), with angels (33.0%) and carrots (25.7%) being less frequent. This is similar to reports of winter sprites over the Sea of Japan and summer ones in central Europe. Other shapes such as trees, wishbones, etc. appear quite rarely. Single element events constitute 16.5% of observations, with 83.5% containing 2 elements or more. Clusters of homogeneous types are slightly more frequent than mixed ones (55%). Our observations suggest winter East Mediterranean thunderstorms to have a vertical structure that is an intermediate type between high tropical convective systems and the lower cloud-top cells in winter thunderstorms over the Sea of Japan. The climatology shows that the Eastern Mediterranean is a major sprite producer during Northern Hemisphere winter, and thus the existing and future optical observation infrastructure in Israel offers ground-based coverage for upcoming space missions that aim to map global sprite activity.

Long-delayed bright dancing sprite with large horizontal displacement from its parent flash

NASA Astrophysics Data System (ADS)

Yang, J.; Lu, G.; Lee, L. J.; Feng, G.

2015-12-01

A long-delayed very bright dancing sprite with large horizontal displacement from its parent flash was observed. The dancing sprite lasted only 60 ms, and the morphology consisted of three fields with two slim dim sprite elements in the first two fields and a very bright large sprite element in the third field, different from other observations. The bright sprite displaced at least 38 km from its parent flash and occurred over comparatively higher cloud top region. The parent flash was positive, with only one return stroke (~24 kA) and obvious continuing current process, and the charge moment change of the stroke was small (roughly the threshold for sprite production). All of the sprite elements occurred during the continuing current period, and the bright sprite induced considerable current. The sprite dancing features may be linked to parent storm electrical structure, dynamics and microphysics, and the parent CG discharge process which was consistent with VHF observations.

Lipid profiles and ischemic stroke risk: variations by sex within racial/ethnic groups

PubMed Central

Gezmu, Tefera; Schneider, Dona; Demissie, Kitaw; Lin, Yong; Giordano, Christine; Gizzi, Martin S

2014-01-01

Evidence implicates lipid abnormalities as important but modifiable risk factors for stroke. This study assesses whether hypercholesterolemia can be used to predict the risk for etiologic subtypes of ischemic stroke between sexes within racial/ethnic groups. Data elements related to stroke risk, diagnosis, and outcomes were abstracted from the medical records of 3,290 acute stroke admissions between 2006 and 2010 at a regional stroke center. Sex comparison within racial/ethnic groups revealed that South Asian and Hispanic men had a higher proportion of ischemic stroke than women, while the inverse was true for Whites and African Americans (P=0.0014). All women, except South Asian women, had higher mean plasma total cholesterol and higher blood circulating low-density lipoprotein levels (≥100 mg/dL) than men at the time of their admissions. The incidence of large-artery atherosclerosis (LAA) was more common among women than men, except among Hispanics, where men tended to have higher incidences. A regression analysis that considered patients diagnosed with either LAA or small-artery occlusion etiologic subtype as the outcomes and high-density lipoproteins and triglycerides as predictors showed inconsistent associations between lipid profiles and the incidence of these subtypes between the sexes within racial/ethnic groups. In conclusion, our investigation suggests that women stroke patients may be at increased risk for stroke etiologic subtype LAA than men. Although the higher prevalence of stroke risk factors examined in this study predicts the increase in the incidence of the disease, lack of knowledge/awareness and lack of affordable treatments for stroke risk factors among women and immigrants/non-US-born subpopulations may explain the observed associations. PMID:24940081

Lipid profiles and ischemic stroke risk: variations by sex within racial/ethnic groups.

PubMed

Gezmu, Tefera; Schneider, Dona; Demissie, Kitaw; Lin, Yong; Giordano, Christine; Gizzi, Martin S

2014-01-01

Evidence implicates lipid abnormalities as important but modifiable risk factors for stroke. This study assesses whether hypercholesterolemia can be used to predict the risk for etiologic subtypes of ischemic stroke between sexes within racial/ethnic groups. Data elements related to stroke risk, diagnosis, and outcomes were abstracted from the medical records of 3,290 acute stroke admissions between 2006 and 2010 at a regional stroke center. Sex comparison within racial/ethnic groups revealed that South Asian and Hispanic men had a higher proportion of ischemic stroke than women, while the inverse was true for Whites and African Americans (P=0.0014). All women, except South Asian women, had higher mean plasma total cholesterol and higher blood circulating low-density lipoprotein levels (≥100 mg/dL) than men at the time of their admissions. The incidence of large-artery atherosclerosis (LAA) was more common among women than men, except among Hispanics, where men tended to have higher incidences. A regression analysis that considered patients diagnosed with either LAA or small-artery occlusion etiologic subtype as the outcomes and high-density lipoproteins and triglycerides as predictors showed inconsistent associations between lipid profiles and the incidence of these subtypes between the sexes within racial/ethnic groups. In conclusion, our investigation suggests that women stroke patients may be at increased risk for stroke etiologic subtype LAA than men. Although the higher prevalence of stroke risk factors examined in this study predicts the increase in the incidence of the disease, lack of knowledge/awareness and lack of affordable treatments for stroke risk factors among women and immigrants/non-US-born subpopulations may explain the observed associations.

Segmentation of touching handwritten Japanese characters using the graph theory method

NASA Astrophysics Data System (ADS)

Suwa, Misako

2000-12-01

Projection analysis methods have been widely used to segment Japanese character strings. However, if adjacent characters have overhanging strokes or a touching point doesn't correspond to the histogram minimum, the methods are prone to result in errors. In contrast, non-projection analysis methods being proposed for use on numerals or alphabet characters cannot be simply applied for Japanese characters because of the differences in the structure of the characters. Based on the oversegmenting strategy, a new pre-segmentation method is presented in this paper: touching patterns are represented as graphs and touching strokes are regarded as the elements of proper edge cutsets. By using the graph theoretical technique, the cutset martrix is calculated. Then, by applying pruning rules, potential touching strokes are determined and the patterns are over segmented. Moreover, this algorithm was confirmed to be valid for touching patterns with overhanging strokes and doubly connected patterns in simulations.

The NASA Lightning Nitrogen Oxides Model (LNOM): Recent Updates and Applications

NASA Technical Reports Server (NTRS)

Koshak, William; Peterson, Harold; Biazar, Arastoo; Khan, Maudood; Wang, Lihua; Park, Yee-Hun

2011-01-01

Improvements to the NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) and its application to the Community Multiscale Air Quality (CMAQ) modeling system are presented. The LNOM analyzes Lightning Mapping Array (LMA) and National Lightning Detection Network(tm) (NLDN) data to estimate the raw (i.e., unmixed and otherwise environmentally unmodified) vertical profile of lightning NOx (= NO + NO2). Lightning channel length distributions and lightning 10-m segment altitude distributions are also provided. In addition to NOx production from lightning return strokes, the LNOM now includes non-return stroke lightning NOx production due to: hot core stepped and dart leaders, stepped leader corona sheath, K-changes, continuing currents, and M-components. The impact of including LNOM-estimates of lightning NOx for an August 2006 run of CMAQ is discussed.

A study on the influence of corona on currents and electromagnetic fields predicted by a nonlinear lightning return-stroke model

NASA Astrophysics Data System (ADS)

De Conti, Alberto; Silveira, Fernando H.; Visacro, Silvério

2014-05-01

This paper investigates the influence of corona on currents and electromagnetic fields predicted by a return-stroke model that represents the lightning channel as a nonuniform transmission line with time-varying (nonlinear) resistance. The corona model used in this paper allows the calculation of corona currents as a function of the radial electric field in the vicinity of the channel. A parametric study is presented to investigate the influence of corona parameters, such as the breakdown electric field and the critical electric field for the stable propagation of streamers, on predicted currents and electromagnetic fields. The results show that, regardless of the assumed corona parameters, the incorporation of corona into the nonuniform and nonlinear transmission line model under investigation modifies the model predictions so that they consistently reproduce most of the typical features of experimentally observed lightning electromagnetic fields and return-stroke speed profiles. In particular, it is shown that the proposed model leads to close vertical electric fields presenting waveforms, amplitudes, and decay with distance in good agreement with dart leader electric field changes measured in triggered lightning experiments. A comparison with popular engineering return-stroke models further confirms the model's ability to predict consistent electric field waveforms in the close vicinity of the channel. Some differences observed in the field amplitudes calculated with the different models can be related to the fact that current distortion, while present in the proposed model, is ultimately neglected in the considered engineering return-stroke models.

Tortuosity of lightning return stroke channels

NASA Technical Reports Server (NTRS)

Levine, D. M.; Gilson, B.

1984-01-01

Data obtained from photographs of lightning are presented on the tortuosity of return stroke channels. The data were obtained by making piecewise linear fits to the channels, and recording the cartesian coordinates of the ends of each linear segment. The mean change between ends of the segments was nearly zero in the horizontal direction and was about eight meters in the vertical direction. Histograms of these changes are presented. These data were used to create model lightning channels and to predict the electric fields radiated during return strokes. This was done using a computer generated random walk in which linear segments were placed end-to-end to form a piecewise linear representation of the channel. The computer selected random numbers for the ends of the segments assuming a normal distribution with the measured statistics. Once the channels were simulated, the electric fields radiated during a return stroke were predicted using a transmission line model on each segment. It was found that realistic channels are obtained with this procedure, but only if the model includes two scales of tortuosity: fine scale irregularities corresponding to the local channel tortuosity which are superimposed on large scale horizontal drifts. The two scales of tortuosity are also necessary to obtain agreement between the electric fields computed mathematically from the simulated channels and the electric fields radiated from real return strokes. Without large scale drifts, the computed electric fields do not have the undulations characteristics of the data.

Vertical motion simulator familiarization guide

NASA Technical Reports Server (NTRS)

Danek, George L.

1993-01-01

The Vertical Motion Simulator Familiarization Guide provides a synoptic description of the Vertical Motion Simulator (VMS) and descriptions of the various simulation components and systems. The intended audience is the community of scientists and engineers who employ the VMS for research and development. The concept of a research simulator system is introduced and the building block nature of the VMS is emphasized. Individual sections describe all the hardware elements in terms of general properties and capabilities. Also included are an example of a typical VMS simulation which graphically illustrates the composition of the system and shows the signal flow among the elements and a glossary of specialized terms, abbreviations, and acronyms.

NUCLEAR REACTOR

DOEpatents

Moore, R.V.; Bowen, J.H.; Dent, K.H.

1958-12-01

A heterogeneous, natural uranium fueled, solid moderated, gas cooled reactor is described, in which the fuel elements are in the form of elongated rods and are dlsposed within vertical coolant channels ln the moderator symmetrically arranged as a regular lattice in groups. This reactor employs control rods which operate in vertical channels in the moderator so that each control rod is centered in one of the fuel element groups. The reactor is enclosed in a pressure vessel which ls provided with access holes at the top to facilitate loading and unloadlng of the fuel elements, control rods and control rod driving devices.

A three-dimensional finite element model of human atrial anatomy: New methods for cubic Hermite meshes with extraordinary vertices

PubMed Central

Gonzales, Matthew J.; Sturgeon, Gregory; Krishnamurthy, Adarsh; Hake, Johan; Jonas, René; Stark, Paul; Rappel, Wouter-Jan; Narayan, Sanjiv M.; Zhang, Yongjie; Segars, W. Paul; McCulloch, Andrew D.

2013-01-01

High-order cubic Hermite finite elements have been valuable in modeling cardiac geometry, fiber orientations, biomechanics, and electrophysiology, but their use in solving three-dimensional problems has been limited to ventricular models with simple topologies. Here, we utilized a subdivision surface scheme and derived a generalization of the “local-to-global” derivative mapping scheme of cubic Hermite finite elements to construct bicubic and tricubic Hermite models of the human atria with extraordinary vertices from computed tomography images of a patient with atrial fibrillation. To an accuracy of 0.6 millimeters, we were able to capture the left atrial geometry with only 142 bicubic Hermite finite elements, and the right atrial geometry with only 90. The left and right atrial bicubic Hermite meshes were G1 continuous everywhere except in the one-neighborhood of extraordinary vertices, where the mean dot products of normals at adjacent elements were 0.928 and 0.925. We also constructed two biatrial tricubic Hermite models and defined fiber orientation fields in agreement with diagrammatic data from the literature using only 42 angle parameters. The meshes all have good quality metrics, uniform element sizes, and elements with aspect ratios near unity, and are shared with the public. These new methods will allow for more compact and efficient patient-specific models of human atrial and whole heart physiology. PMID:23602918

Arm to leg coordination in elite butterfly swimmers.

PubMed

Chollet, D; Seifert, L; Boulesteix, L; Carter, M

2006-04-01

This study proposed the use of four time gaps to assess arm-to-leg coordination in the butterfly stroke at increasing race paces. Fourteen elite male swimmers swam at four velocities corresponding to the appropriate paces for, respectively, the 400-m, 200-m, 100-m, and 50-m events. The different stroke phases of the arm and leg were identified by video analysis and then used to calculate four time gaps (T1: time gap between entry of the hands in the water and the high break-even point of the first undulation; T2: time gap between the beginning of the hands' backward movement and the low break-even point of the first undulation; T3: time gap between the hands' arrival in a vertical plane to the shoulders and the high break-even point of the second undulation; T4: time gap between the hands' release from the water and the low break-even point of the second undulation), the values of which described the changing relationship of arm to leg movements over an entire stroke cycle. With increases in pace, elite swimmers increased the stroke rate, the relative duration of the arm pull, the recovery and the first downward movement of the legs, and decreased the stroke length, the relative duration of the arm catch phase and the body glide with arms forward (measured by T2), until continuity in the propulsive actions was achieved. Whatever the paces, the T1, T3, and T4 values were close to zero and revealed a high degree of synchronisation at key motor points of the arm and leg actions. This new method to assess butterfly coordination could facilitate learning and coaching by situating the place of the leg undulation in relation with the arm stroke.

Posterior insular cortex – a site of vestibular–somatosensory interaction?

PubMed Central

Baier, Bernhard; zu Eulenburg, Peter; Best, Christoph; Geber, Christian; Müller-Forell, Wibke; Birklein, Frank; Dieterich, Marianne

2013-01-01

Background In previous imaging studies the insular cortex (IC) has been identified as an essential part of the processing of a wide spectrum of perception and sensorimotor integration. Yet, there are no systematic lesion studies in a sufficient number of patients examining whether processing of vestibular and the interaction of somatosensory and vestibular signals take place in the IC. Methods We investigated acute stroke patients with lesions affecting the IC in order to fill this gap. In detail, we explored signs of a vestibular tone imbalance such as the deviation of the subjective visual vertical (SVV). We applied voxel-lesion behaviour mapping analysis in 27 patients with acute unilateral stroke. Results Our data demonstrate that patients with lesions of the posterior IC have an abnormal tilt of SVV. Furthermore, re-analysing data of 20 patients from a previous study, we found a positive correlation between thermal perception contralateral to the stroke and the severity of the SVV tilt. Conclusions We conclude that the IC is a sensory brain region where different modalities might interact. PMID:24392273

VIEW OF PROCESS DEVELOPMENT PILE (PDP) TANK TOP, WITH VERTICAL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF PROCESS DEVELOPMENT PILE (PDP) TANK TOP, WITH VERTICAL ELEMENTS IN BACKGROUND, LEVEL 0’, LOOKING NORTHWEST - Physics Assembly Laboratory, Area A/M, Savannah River Site, Aiken, Aiken County, SC

Stress distribution in maxillary first molar periodontium using straight pull headgear with vertical and horizontal tubes: A finite element analysis.

PubMed

Feizbakhsh, Masood; Kadkhodaei, Mahmoud; Zandian, Dana; Hosseinpour, Zahra

2017-01-01

One of the most effective ways for distal movement of molars to treat Class II malocclusion is using extraoral force through a headgear device. The purpose of this study was the comparison of stress distribution in maxillary first molar periodontium using straight pull headgear in vertical and horizontal tubes through finite element method. Based on the real geometry model, a basic model of the first molar and maxillary bone was obtained using three-dimensional imaging of the skull. After the geometric modeling of periodontium components through CATIA software and the definition of mechanical properties and element classification, a force of 150 g for each headgear was defined in ABAQUS software. Consequently, Von Mises and Principal stresses were evaluated. The statistical analysis was performed using T-paired and Wilcoxon nonparametric tests. Extension of areas with Von Mises and Principal stresses utilizing straight pull headgear with a vertical tube was not different from that of using a horizontal tube, but the numerical value of the Von Mises stress in the vertical tube was significantly reduced ( P < 0/05). On the other hand, the difference of the principal stress between both tubes was not significant ( P > 0/05). Based on the results, when force applied to the straight pull headgear with a vertical tube, Von Mises stress was reduced significantly in comparison with the horizontal tube. Therefore, to correct the mesiolingual movement of the maxillary first molar, vertical headgear tube is recommended.

Implication of the recent positive endovascular intervention trials for organizing acute stroke care: European perspective.

PubMed

Tatlisumak, Turgut

2015-06-01

Timely recanalization leads to improved patient outcomes in acute ischemic stroke. Recent trial results demonstrated a strong benefit for endovascular therapies over standard medical care in patients with acute ischemic stroke and a major intracranial artery occlusion≤6 hours or even beyond from symptom onset and independent of patients' age. Previous studies have shown the benefit of intravenous thrombolysis that had gradually, albeit slowly, reshaped acute stroke care worldwide. Now, given the superior benefits of endovascular intervention, the whole structure of acute stroke care needs to be reorganized to meet patient needs and to deliver evidence-based treatments effectively. However, a blueprint for success with novel stroke treatments should be composed of numerous elements and requires efforts from various parties. Regarding the endovascular therapies, the strengths of Europe include highly organized democratic society structures, high rate of urbanization, well-developed revenue-based healthcare systems, and high income levels, whereas the obstacles include the east-west disparity in wealth, the ongoing economic crisis hindering spread of fairly costly new treatments, and the quickly aging population putting more demands on health care in general. Regional and national plans for covering whole population with 24/7 adequate acute stroke care are necessary in close cooperation of professionals and decision-makers. Europe-wide new training programs for expert physicians in stroke care should be initiated shortly. European Stroke Organisation has a unique role in providing expertise, consultation, guidelines, and versatile training in meeting new demands in stroke care. This article discusses the current situation, prospects, and challenges in Europe offering personal views on potential solutions. © 2015 American Heart Association, Inc.

Fire-Heat and Qi Deficiency Syndromes as Predictors of Short-term Prognosis of Acute Ischemic Stroke

PubMed Central

Cheng, Shu-Chen; Lin, Chien-Hsiung; Chang, Yeu-Jhy; Lee, Tsong-Hai; Ryu, Shan-Jin; Chen, Chun-Hsien; Chang, Her-Kun; Chang, Chee-Jen

2013-01-01

Abstract Objectives To explore the relationships between traditional Chinese medicine (TCM) syndromes and disease severity and prognoses after ischemic stroke, such as neurologic deficits and decline in activities of daily living (ADLs). Methods The study included 211 patients who met the inclusion criteria of acute ischemic stroke based on clinical manifestations, computed tomography or magnetic resonance imaging findings, and onset of ischemic stroke within 72 hours with clear consciousness. To assess neurologic function and ADLs in patients with different TCM syndromes, the TCM Syndrome Differentiation Diagnostic Criteria for Apoplexy scale (containing assessments of wind, phlegm, blood stasis, fire-heat, qi deficiency, and yin deficiency with yang hyperactivity syndromes) was used within 72 hours of stroke onset, and Western medicine–based National Institutes of Health Stroke Scale (NIHSS) and Barthel Index (BI) assessments were performed at both admission and discharge. Results The most frequent TCM syndromes associated with acute ischemic stroke were wind syndrome, phlegm syndrome, and blood stasis syndrome. Improvement according to the BI at discharge and days of admission were significantly different between patients with and those without fire-heat syndrome. Patients with qi deficiency syndrome had longer hospital stays and worse NIHSS and BI assessments at discharge than patients without qi deficiency syndrome. All the reported differences reached statistical significance. Conclusions These results provide evidence that fire-heat syndrome and qi deficiency syndrome are essential elements that can predict short-term prognosis of acute ischemic stroke. PMID:23600945

REACTOR UNLOADING

DOEpatents

Leverett, M.C.

1958-02-18

This patent is related to gas cooled reactors wherein the fuel elements are disposed in vertical channels extending through the reactor core, the cooling gas passing through the channels from the bottom to the top of the core. The invention is a means for unloading the fuel elements from the core and comprises dump values in the form of flat cars mounted on wheels at the bottom of the core structure which support vertical stacks of fuel elements. When the flat cars are moved, either manually or automatically, for normal unloading purposes, or due to a rapid rise in the reproduction ratio within the core, the fuel elements are permtted to fall by gravity out of the core structure thereby reducing the reproduction ratio or stopping the reaction as desired.

Protocol for a prospective interventional trial to develop a diagnostic index test for stroke as a cause of vertigo, dizziness and imbalance in the emergency room (EMVERT study).

PubMed

Möhwald, Ken; Bardins, Stanislavs; Müller, Hans-Helge; Jahn, Klaus; Zwergal, Andreas

2017-10-10

Identifying stroke as a cause of acute vertigo, dizziness and imbalance in the emergency room is still a clinical challenge. Many patients are admitted to stroke units, but only a minority will have strokes. This imposes a heavy financial burden on the healthcare system. The aim of this study is to develop a diagnostic index test to identify patients with a high risk of having a stroke as the cause of acute vertigo and imbalance. Patients with acute onset of vertigo, dizziness, postural imbalance or double vision within the last 24 hours lasting for at least 10 min are eligible to be included in the study. Patients with clinically proven peripheral or central aetiology will be excluded. In the emergency room, all enrolled patients will undergo standardised neuro-ophthalmological/physiological testing (including video-oculography, mobile posturography, measurement of subjective visual vertical) (EMVERT block 1). Within 10 days, standardised MRI will be performed as a reference test to identify stroke (EMVERT block 2). Data from EMVERT block 2 will be compared with results from block 1 in order to devise a diagnostic index test with a high specificity and sensitivity to predict the risk of stroke in the emergency room. The study was approved by the ethics committee of the University of Munich and will be conducted according to the Guideline for Good Clinical Practice, the Federal Data Protecting Act and the Helsinki Declaration of the World Medical Association in its recent version. Study results are expected to be published in international peer-reviewed journals and will be presented at international conferences. German Clinical Trial Register: DRKS00008992; Universal trial number: U1111-1172-8719); pre-results. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Protocol for a prospective interventional trial to develop a diagnostic index test for stroke as a cause of vertigo, dizziness and imbalance in the emergency room (EMVERT study)

PubMed Central

Bardins, Stanislavs; Müller, Hans-Helge; Jahn, Klaus; Zwergal, Andreas

2017-01-01

Introduction Identifying stroke as a cause of acute vertigo, dizziness and imbalance in the emergency room is still a clinical challenge. Many patients are admitted to stroke units, but only a minority will have strokes. This imposes a heavy financial burden on the healthcare system. The aim of this study is to develop a diagnostic index test to identify patients with a high risk of having a stroke as the cause of acute vertigo and imbalance. Methods and analysis Patients with acute onset of vertigo, dizziness, postural imbalance or double vision within the last 24 hours lasting for at least 10 min are eligible to be included in the study. Patients with clinically proven peripheral or central aetiology will be excluded. In the emergency room, all enrolled patients will undergo standardised neuro-ophthalmological/physiological testing (including video-oculography, mobile posturography, measurement of subjective visual vertical) (EMVERT block 1). Within 10 days, standardised MRI will be performed as a reference test to identify stroke (EMVERT block 2). Data from EMVERT block 2 will be compared with results from block 1 in order to devise a diagnostic index test with a high specificity and sensitivity to predict the risk of stroke in the emergency room. Ethics and dissemination The study was approved by the ethics committee of the University of Munich and will be conducted according to the Guideline for Good Clinical Practice, the Federal Data Protecting Act and the Helsinki Declaration of the World Medical Association in its recent version. Study results are expected to be published in international peer-reviewed journals and will be presented at international conferences. Trial registration number German Clinical Trial Register: DRKS00008992; Universal trial number: U1111-1172-8719); pre-results. PMID:29018076

Experimental characterization of shape memory alloy actuator cables

NASA Astrophysics Data System (ADS)

Biggs, Daniel B.; Shaw, John A.

2016-04-01

Wire rope (or cables) are a fundamental structural element in many engineering applications. Recently, there has been growing interest in stranding NiTi wires into cables to scale up the adaptive properties of NiTi tension elements and to make use of the desirable properties of wire rope. Exploratory experiments were performed to study the actuation behavior of two NiTi shape memory alloy cables and straight monofilament wire of the same material. The specimens were held under various dead loads ranging from 50 MPa to 400 MPa and thermally cycled 25 times from 140°C to 5°C at a rate of 12°C/min. Performance metrics of actuation stroke, residual strain, and work output were measured and compared between specimen types. The 7x7 cable exhibited similar actuation to the single straight wire, but with slightly longer stroke and marginally more shakedown, while maintaining equivalent specific work output. This leads to the conclusion that the 7x7 cable effectively scaled up the adaptive properties the straight wire. Under loads below 150 MPa, the 1x27 cable had up to double the actuation stroke and work output, but exhibited larger shakedown and poorer performance when loaded higher.

Quantification of image contrast of infarcts on computed tomography scans.

PubMed

Gomolka, R S; Chrzan, R M; Urbanik, A; Kazmierski, R; Grzanka, A D; Nowinski, W L

2017-02-01

Introduction Accurate identification of infarcts in non-contrast computed tomography (NC-CT) scans of the brain is fundamental in the diagnosis and management of patients with stroke. Quantification of image contrast properties at the boundaries of ischemic infarct regions in NC-CT can contribute to a more precise manual or automatic delineation of these regions. Here we explore these properties quantitatively. Methods We retrospectively investigated 519 NC-CT studies of 425 patients with clinically confirmed ischemic strokes. The average and standard deviation (SD) of patients' age was 67.5 ± 12.4 years and the average(median)±SD time from symptoms onset to NC-CT examination was 27.4(12)±35.7 h. For every scan with an ischemic lesion identified by experts, the image contrast of the lesion vs. normal surrounding parenchyma was calculated as a difference of mean Hounsfield Unit (HU) of 1-5 consecutive voxels (the contrast window width) belonging to the lesion and to the parenchyma. This contrast was calculated at each single voxel of ischemic lesion boundaries (previously delineated by the experts) in horizontal and vertical directions in each image. The distributions of obtained horizontal, vertical and both contrasts combined were calculated among all 519 NC-CTs. Results The highest applicative contrast window width was identified as 5 voxels. The ischemic infarcts were found to be characterized by 6.60 HU, 8.28 HU and 7.55 HU mean values for distributions of horizontal, vertical and combined contrasts. Approximately 40-50% of the infarct boundary voxels were found to refer to the image contrast below 5 HU. Conclusion Low image contrast of ischemic lesions prevents accurate delineation of the infarcts in NC-CT.

An anatomical and psychophysical comparison of subjective verticals in patients with right brain damage.

PubMed

Rousseaux, Marc; Braem, Bérenger; Honoré, Jacques; Saj, Arnaud

2015-08-01

Brain hemisphere lesions often cause a contralesional tilt of the subjective vertical (SV) a phenomenon related to spatial neglect and postural disorders. Depending on the method employed, different perceptual systems come into play when this gravitational vertical is assessed. Here, we compared the anatomical and psychophysical characteristics of modality-dependent SV biases in patients with right hemisphere stroke. The SV was measured with visual, haptic and visual-haptic modalities (SV, SVV, SVHV) in 46 patients with a relatively recent stroke. Voxel-based lesion-symptom mapping (performed with NPM(®)) was used to highlight brain areas in which lesions best explained the severity of task biases (p < .05). Lesions explaining the SVV tilt (TSVV) were centered on the posterior part of the middle temporal gyrus, those explaining the TSHV were more limited and anterior, without convergence with the former. Lesions explaining the TSVHV were centered on the superior temporal gyrus and more anterior those explaining the TSVV, with convergence with lesions explaining both the TSVV and the TSHV. Patients showed counterclockwise deviations in the SVs. Constant and variable errors were greater for the SHV than for the SVV and for the SVHV. The TSVV and TVHV were closely related to the presence of left spatial neglect and hemianopia. Errors in the SVV and (at a lesser degree) SVHV were preferentially related to lesions in visual associative cortex. The SVV and especially the SVHV provide valuable estimates of patient difficulties, in view of the lower associated variable errors (i.e., greater precision) and closer relationships with clinical disorders. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Quiescent-Chamber Type Compression-Ignition Engine

NASA Technical Reports Server (NTRS)

Foster, H H

1937-01-01

Report presents the results of performance tests of a single-cylinder 4-stroke-cycle compression-ignition engine having a vertical disk form of combustion chamber without air flow. The number, size, and direction of the orifices of the fuel-injection nozzles used were independently varied. A table and graphs are presented showing the performance of the engine with different nozzles; results of tests at different compression ratios, boost pressures, and coolant temperatures are also included.

Experimental study of auxetic behavior of cellular structure

NASA Astrophysics Data System (ADS)

Chentsov, A. V.; Lisovenko, D. S.

2018-04-01

The uniaxial tension of two-dimensional auxetic cellular constructions is studied experimentally. Samples were made of nonauxetic polyethylene terephthalate (PET-A amorphous) and subjected to monotonous uniaxial tension until the last moment when they still remained plane. As a result of the experimental data analysis, comparison of the mechanical properties is given for a faultless sample and constructions in which one horizontal or vertical element in the central area of the sample was removed. It is shown that the lack of one horizontal element of the construction has little influence on the auxetic properties of these constructions unlike the structures with one vertical element being absent.

HIGH TEMPERATURE, HIGH POWER HETEROGENEOUS NUCLEAR REACTOR

DOEpatents

Hammond, R.P.; Wykoff, W.R.; Busey, H.M.

1960-06-14

A heterogeneous nuclear reactor is designed comprising a stationary housing and a rotatable annular core being supported for rotation about a vertical axis in the housing, the core containing a plurality of radial fuel- element supporting channels, the cylindrical empty space along the axis of the core providing a central plenum for the disposal of spent fuel elements, the core cross section outer periphery being vertically gradated in radius one end from the other to provide a coolant duct between the core and the housing, and means for inserting fresh fuel elements in the supporting channels under pressure and while the reactor is in operation.

Verification of a non-hydrostatic dynamical core using the horizontal spectral element method and vertical finite difference method: 2-D aspects

NASA Astrophysics Data System (ADS)

Choi, S.-J.; Giraldo, F. X.; Kim, J.; Shin, S.

2014-11-01

The non-hydrostatic (NH) compressible Euler equations for dry atmosphere were solved in a simplified two-dimensional (2-D) slice framework employing a spectral element method (SEM) for the horizontal discretization and a finite difference method (FDM) for the vertical discretization. By using horizontal SEM, which decomposes the physical domain into smaller pieces with a small communication stencil, a high level of scalability can be achieved. By using vertical FDM, an easy method for coupling the dynamics and existing physics packages can be provided. The SEM uses high-order nodal basis functions associated with Lagrange polynomials based on Gauss-Lobatto-Legendre (GLL) quadrature points. The FDM employs a third-order upwind-biased scheme for the vertical flux terms and a centered finite difference scheme for the vertical derivative and integral terms. For temporal integration, a time-split, third-order Runge-Kutta (RK3) integration technique was applied. The Euler equations that were used here are in flux form based on the hydrostatic pressure vertical coordinate. The equations are the same as those used in the Weather Research and Forecasting (WRF) model, but a hybrid sigma-pressure vertical coordinate was implemented in this model. We validated the model by conducting the widely used standard tests: linear hydrostatic mountain wave, tracer advection, and gravity wave over the Schär-type mountain, as well as density current, inertia-gravity wave, and rising thermal bubble. The results from these tests demonstrated that the model using the horizontal SEM and the vertical FDM is accurate and robust provided sufficient diffusion is applied. The results with various horizontal resolutions also showed convergence of second-order accuracy due to the accuracy of the time integration scheme and that of the vertical direction, although high-order basis functions were used in the horizontal. By using the 2-D slice model, we effectively showed that the combined spatial discretization method of the spectral element and finite difference methods in the horizontal and vertical directions, respectively, offers a viable method for development of an NH dynamical core.

Center of mass detection via an active pixel sensor

NASA Technical Reports Server (NTRS)

Yadid-Pecht, Orly (Inventor); Minch, Brad (Inventor); Pain, Bedabrata (Inventor); Fossum, Eric (Inventor)

2005-01-01

An imaging system for identifying the location of the center of mass (COM) in an image. In one aspect, an imaging system includes a plurality of photosensitive elements arranged in a matrix. A center of mass circuit coupled to the photosensitive elements includes a resistive network and a normalization circuit including at least one bipolar transistor. The center of mass circuit identifies a center of mass location in the matrix and includes: a row circuit, where the row circuit identifies a center of mass row value in each row of the matrix and identifies a row intensity for each row; a horizontal circuit, where the horizontal circuit identifies a center of mass horizontal value; and a vertical circuit, where the vertical circuit identifies a center of mass vertical value. The horizontal and vertical center of mass values indicate the coordinates of the center of mass location for the image.

Center of mass detection via an active pixel sensor

NASA Technical Reports Server (NTRS)

Yadid-Pecht, Orly (Inventor); Minch, Brad (Inventor); Pain, Bedabrara (Inventor); Fossum, Eric (Inventor)

2006-01-01

An imaging system for identifying the location of the center of mass (COM) in an image. In one aspect, an imaging system includes a plurality of photosensitive elements arranged in a matrix. A center of mass circuit coupled to the photosensitive elements includes a resistive network and a normalization circuit including at least one bipolar transistor. The center of mass circuit identifies a center of mass location in the matrix and includes: a row circuit, where the row circuit identifies a center of mass row value in each row of the matrix and identifies a row intensity for each row; a horizontal circuit, where the horizontal circuit identifies a center of mass horizontal value; and a vertical circuit, where the vertical circuit identifies a center of mass vertical value. The horizontal and vertical center of mass values indicate the coordinates of the center of mass location for the image.

Center of mass detection via an active pixel sensor

NASA Technical Reports Server (NTRS)

Yadid-Pecht, Orly (Inventor); Minch, Brad (Inventor); Pain, Bedabrata (Inventor); Fossum, Eric (Inventor)

2002-01-01

An imaging system for identifying the location of the center of mass (COM) in an image. In one aspect, an imaging system includes a plurality of photosensitive elements arranged in a matrix. A center of mass circuit coupled to the photosensitive elements includes a resistive network and a normalization circuit including at least one bipolar transistor. The center of mass circuit identifies a center of mass location in the matrix and includes: a row circuit, where the row circuit identifies a center of mass row value in each row of the matrix and identifies a row intensity for each row; a horizontal circuit, where the horizontal circuit identifies a center of mass horizontal value; and a vertical circuit, where the vertical circuit identifies a center of mass vertical value. The horizontal and vertical center of mass values indicate the coordinates of the center of mass location for the image.

Spatial displacement of numbers on a vertical number line in spatial neglect.

PubMed

Mihulowicz, Urszula; Klein, Elise; Nuerk, Hans-Christoph; Willmes, Klaus; Karnath, Hans-Otto

2015-01-01

Previous studies that investigated the association of numbers and space in humans came to contradictory conclusions about the spatial character of the mental number magnitude representation and about how it may be influenced by unilateral spatial neglect. The present study aimed to disentangle the debated influence of perceptual vs. representational aspects via explicit mapping of numbers onto space by applying the number line estimation paradigm with vertical orientation of stimulus lines. Thirty-five acute right-brain damaged stroke patients (6 with neglect) were asked to place two-digit numbers on vertically oriented lines with 0 marked at the bottom and 100 at the top. In contrast to the expected, nearly linear mapping in the control patient group, patients with spatial neglect overestimated the position of numbers in the lower middle range. The results corroborate spatial characteristics of the number magnitude representation. In neglect patients, this representation seems to be biased towards the ipsilesional side, independent of the physical orientation of the task stimuli.

Determination of rare earth elements concentration at different depth profile of Precambrian pegmatites using instrumental neutron activation analysis.

PubMed

Sadiq Aliyu, Abubakar; Musa, Yahaya; Liman, M S; Abba, Habu T; Chaanda, Mohammed S; Ngene, Nnamani C; Garba, N N

2018-01-01

The Keffi area hosts abundant pegmatite bodies as a result of the surrounding granitic intrusions. Keffi is part of areas that are geologically classified as North Central Basement Complex. Data on the mineralogy and mineralogical zonation of the Keffi pegmatite are scanty. Hence the need to understand the geology and mineralogical zonation of Keffi pegmatites especially at different depth profiles is relevant as a study of the elemental composition of the pegmatite is essential for the estimation of its economic viability. Here, the relative standardization method of instrumental neutron activation analysis (INAA) has been used to investigate the vertical deviations of the elemental concentrations of rare earth elements (REEs) at different depth profile of Keffi pegmatite. This study adopted the following metrics in investigating the vertical variations of REEs concentrations. Namely, the total contents of rare earth elements (∑REE); ratio of light to heavy rare earth elements (LREE/HREE), which defines the enrichment or depletion of REEs; europium anomaly (Eu/Sm); La/Lu ratio relative to chondritic meteorites. The study showed no significant variations in the total content of rare elements between the vertical depth profiles (100-250m). However, higher total concentrations of REEs (~ 92.65ppm) were recorded at the upper depth of the pegmatite and the europium anomaly was consistently negative at all the depth profiles suggesting that the Keffi pegmatite is enriched with light REEs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Conceptions of Height and Verticality in the History of Skyscrapers and Skylines

NASA Astrophysics Data System (ADS)

Maslovskaya, Oksana; Ignatov, Grigoriy

2018-03-01

The main goal of this article is to reveal the significance of height and verticality history of skyscrapers and skylines. The objectives are as follows: 1. trace the origin of design concepts related to skyscraper; 2. discuss the perceived experience of the cultural aspects of skyscrapers and skylines; 3. describe the differences and similarities of the profiles of with comparable skylines. The methodology of study is designed to explore the perceived theory and principals of skyscraper and skyline development phenomenon and its key features. The skyscraper reveals an assertive creative form of vertical design. Skyscraper construction also relates to the origin of ancient cultural symbolism as the dominant vertical element as the main features of an ordered space. The historical idea of height reaches back to the earliest civilization such as the Tower of Babel. Philosophical approaches of elements of such post-structuralism have been included in studying of skyscraper phenomenon. The analysis of skyscraper and their resulting skyline are examined to show the connection to their origins with their concepts of height and verticality. From the historical perspective, cities with skyscrapers and a skyline turn out to be an assertive manifestation of common ideas of height and verticality.

Apical stress distribution under vertical compaction of gutta-percha and occlusal loads in canals with varying apical sizes: a three-dimensional finite element analysis.

PubMed

Yuan, K; Niu, C; Xie, Q; Jiang, W; Gao, L; Ma, R; Huang, Z

2018-02-01

To investigate and compare the effects of two apical canal instrumentation protocols on apical stress distribution at the root apex under vertical compaction of gutta-percha and occlusal loads using finite element analysis. Three finite element analysis models of a mandibular first premolar were reconstructed: an original canal model, a size 35, .04 taper apical canal enlargement model and a Lightspeed size 60 apical canal enlargement model. A 15 N compaction force was applied vertically to the gutta-percha 5 mm from the apex. A 175 N occlusal load in two directions (vertical and 45° to the longitudinal axis of the tooth) was simulated. Stresses in the apical 2 mm of the root were calculated and compared among the three models. Under vertical compaction, stresses in the apical canal instrumented by Lightspeed size 60 (maximal 3.3 MPa) were higher than that of the size 35, .04 taper model (maximal 1.3 MPa). In the case of the two occlusal forces, the Lightspeed size 60 apical enlargement was associated with the greatest stress distribution in the apical region. The greatest stress and the most obvious stress difference between the models appeared at the tip of the root when occlusal and vertical compaction loads were applied. Apical enlargement caused stress distribution changes in the apical region of roots. The larger apical size led to higher stress concentration at the root apex. © 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Stress distribution in maxillary first molar periodontium using straight pull headgear with vertical and horizontal tubes: A finite element analysis

PubMed Central

Feizbakhsh, Masood; Kadkhodaei, Mahmoud; Zandian, Dana; Hosseinpour, Zahra

2017-01-01

Background: One of the most effective ways for distal movement of molars to treat Class II malocclusion is using extraoral force through a headgear device. The purpose of this study was the comparison of stress distribution in maxillary first molar periodontium using straight pull headgear in vertical and horizontal tubes through finite element method. Materials and Methods: Based on the real geometry model, a basic model of the first molar and maxillary bone was obtained using three-dimensional imaging of the skull. After the geometric modeling of periodontium components through CATIA software and the definition of mechanical properties and element classification, a force of 150 g for each headgear was defined in ABAQUS software. Consequently, Von Mises and Principal stresses were evaluated. The statistical analysis was performed using T-paired and Wilcoxon nonparametric tests. Results: Extension of areas with Von Mises and Principal stresses utilizing straight pull headgear with a vertical tube was not different from that of using a horizontal tube, but the numerical value of the Von Mises stress in the vertical tube was significantly reduced (P < 0/05). On the other hand, the difference of the principal stress between both tubes was not significant (P > 0/05). Conclusion: Based on the results, when force applied to the straight pull headgear with a vertical tube, Von Mises stress was reduced significantly in comparison with the horizontal tube. Therefore, to correct the mesiolingual movement of the maxillary first molar, vertical headgear tube is recommended. PMID:28584535

Design and test of a Microsoft Kinect-based system for delivering adaptive visual feedback to stroke patients during training of upper limb movement.

PubMed

Simonsen, Daniel; Popovic, Mirjana B; Spaich, Erika G; Andersen, Ole Kæseler

2017-11-01

The present paper describes the design and test of a low-cost Microsoft Kinect-based system for delivering adaptive visual feedback to stroke patients during the execution of an upper limb exercise. Eleven sub-acute stroke patients with varying degrees of upper limb function were recruited. Each subject participated in a control session (repeated twice) and a feedback session (repeated twice). In each session, the subjects were presented with a rectangular pattern displayed on a vertical mounted monitor embedded in the table in front of the patient. The subjects were asked to move a marker inside the rectangular pattern by using their most affected hand. During the feedback session, the thickness of the rectangular pattern was changed according to the performance of the subject, and the color of the marker changed according to its position, thereby guiding the subject's movements. In the control session, the thickness of the rectangular pattern and the color of the marker did not change. The results showed that the movement similarity and smoothness was higher in the feedback session than in the control session while the duration of the movement was longer. The present study showed that adaptive visual feedback delivered by use of the Kinect sensor can increase the similarity and smoothness of upper limb movement in stroke patients.

The effect of vertical bracket positioning on torque and the resultant stress in the periodontal ligament--a finite element study.

PubMed

Sardarian, Ahmadreza; Danaei, Shahla Momeni; Shahidi, Shoaleh; Boushehri, Sahar Ghodsi; Geramy, Allahyar

2014-01-01

The ideal built-in tip and torque values of the straight wire appliance reduce the need for wire bending and hence reduce chair time. The vertical position of the bracket on the tooth surface can alter the torque exerted on the tooth. This is a result of the altered surface curvature observed at each vertical position. To further clarify the role of vertical bracket positioning on the applied torque and the resultant stresses in the periodontal ligament (PDL), we designed a mandibular first premolar using finite element modeling. Cone beam computed tomography of 52 patients (83 lower first premolars) was selected to be included in the study. Curvature was measured for points along the labial surface with increasing distances (0.5 mm increments) from the cusp tip by calculating the angle between tangents drawn from these points and the axis joining the cusp tip and the root apex. The mean values for each distance were calculated, and a finite element model was designed incorporating these mean values. The resultant stress and hydrostatic pressure in the PDL were calculated using finite element analysis. The labial surface of the mandibular first premolar demonstrated a 26.39° change from 2.5 to 6 mm from the cusp tip. The maximum Von-Mises stress and hydrostatic pressure in the PDL were observed at the root apex for all of the bracket positions, and these values demonstrated, respectively, a change of up to 0.059 and 0.186 MPa between two successive points. It can be concluded that the variation in the vertical position of the bracket can have an important effect on the torque and subsequently on the stresses and pressures in the PDL.

Process improvement methodologies uncover unexpected gaps in stroke care.

PubMed

Kuner, Anthony D; Schemmel, Andrew J; Pooler, B Dustin; Yu, John-Paul J

2018-01-01

Background The diagnosis and treatment of acute stroke requires timed and coordinated effort across multiple clinical teams. Purpose To analyze the frequency and temporal distribution of emergent stroke evaluations (ESEs) to identify potential contributory workflow factors that may delay the initiation and subsequent evaluation of emergency department stroke patients. Material and Methods A total of 719 sentinel ESEs with concurrent neuroimaging were identified over a 22-month retrospective time period. Frequency data were tabulated and odds ratios calculated. Results Of all ESEs, 5% occur between 01:00 and 07:00. ESEs were most frequent during the late morning and early afternoon hours (10:00-14:00). Unexpectedly, there was a statistically significant decline in the frequency of ESEs that occur at the 14:00 time point. Conclusion Temporal analysis of ESEs in the emergency department allowed us to identify an unexpected decrease in ESEs and through process improvement methodologies (Lean and Six Sigma) and identify potential workflow elements contributing to this observation.

Landing Characteristics of a Reentry Capsule with a Torus-Shaped Air Bag for Load Alleviation

NASA Technical Reports Server (NTRS)

McGehee, John R.; Hathaway, Melvin E.

1960-01-01

An experimental investigation has been made to determine the landing characteristics of a conical-shaped reentry capsule by using torus-shaped air bags for impact-load alleviation. An impact bag was attached below the large end of the capsule to absorb initial impact loads and a second bag was attached around the canister to absorb loads resulting from impact on the canister when the capsule overturned. A 1/6-scale dynamic model of the configuration was tested for nominal flight paths of 60 deg. and 90 deg. (vertical), a range of contact attitudes from -25 deg. to 30 deg., and a vertical contact velocity of 12.25 feet per second. Accelerations were measured along the X-axis (roll) and Z-axis (yaw) by accelerometers rigidly installed at the center of gravity of the model. Actual flight path, contact attitudes, and motions were determined from high-speed motion pictures. Landings were made on concrete and on water. The peak accelerations along the X-axis for landings on concrete were in the order of 3Og for a 0 deg. contact attitude. A horizontal velocity of 7 feet per second, corresponding to a flight path of 60 deg., had very little effect upon the peak accelerations obtained for landings on concrete. For contact attitudes of -25 deg. and 30 deg. the peak accelerations along the Z-axis were about +/- l5g, respectively. The peak accelerations measured for the water landings were about one-third lower than the peak accelerations measured for the landings on concrete. Assuming a rigid body, computations were made by using Newton's second law of motion and the force-stroke characteristics of the air bag to determine accelerations for a flight path of 90 deg. (vertical) and a contact attitude of 0 deg. The computed and experimental peak accelerations and strokes at peak acceleration were in good agreement for the model. The special scaling appears to be applicable for predicting full-scale time and stroke at peak acceleration for a landing on concrete from a 90 deg. flight path at a 0 deg. It appears that the full-scale approximately the same as those obtained from the model for the range of attitudes and flight paths investigated.

Trajectory Control and Optimization for Responsive Spacecraft

DTIC Science & Technology

2012-03-22

Orbital Elements and Local-Vertical-Local-Horizontal Frame 10 2.3 Equinoctial Frame with respect to ECI Frame [17] . . . . . . . . . 14 3.1...position and velocity, classical orbital elements , and equinoctial elements . These methods are detailed in the following sections. 2.1.1 Inertial Position...trajectory. However, if the singularities are unavoidable equinoctial orbital elements could be used. 2.1.3 Equinoctial Elements . Equinoctial

Large Artery Atherosclerotic Occlusive Disease.

PubMed

Cole, John W

2017-02-01

Extracranial or intracranial large artery atherosclerosis is often identified as a potential etiologic cause for ischemic stroke and transient ischemic attack. Given the high prevalence of large artery atherosclerosis in the general population, determining whether an identified atherosclerotic lesion is truly the cause of a patient's symptomatology can be difficult. In all cases, optimally treating each patient to minimize future stroke risk is paramount. Extracranial or intracranial large artery atherosclerosis can be broadly compartmentalized into four distinct clinical scenarios based upon the individual patient's history, examination, and anatomic imaging findings: asymptomatic and symptomatic extracranial carotid stenosis, intracranial atherosclerosis, and extracranial vertebral artery atherosclerotic disease. This review provides a framework for clinicians evaluating and treating such patients. Intensive medical therapy achieves low rates of stroke and death in asymptomatic carotid stenosis. Evidence indicates that patients with severe symptomatic carotid stenosis should undergo carotid revascularization sooner rather than later and that the risk of stroke or death is lower using carotid endarterectomy than with carotid stenting. Specific to stenting, the risk of stroke or death is greatest among older patients and women. Continuous vascular risk factor optimization via sustained behavioral modifications and intensive medical therapy is the mainstay for stroke prevention in the setting of intracranial and vertebral artery origin atherosclerosis. Lifelong vascular risk factor optimization via sustained behavioral modifications and intensive medical therapy are the key elements to reduce future stroke risk in the setting of large artery atherosclerosis. When considering a revascularization procedure for carotid stenosis, patient demographics, comorbidities, and the periprocedural risks of stroke and death should be carefully considered.

Large Artery Atherosclerotic Occlusive Disease

PubMed Central

Cole, John W.

2017-01-01

ABSTRACT Purpose of Review: Extracranial or intracranial large artery atherosclerosis is often identified as a potential etiologic cause for ischemic stroke and transient ischemic attack. Given the high prevalence of large artery atherosclerosis in the general population, determining whether an identified atherosclerotic lesion is truly the cause of a patient’s symptomatology can be difficult. In all cases, optimally treating each patient to minimize future stroke risk is paramount. Extracranial or intracranial large artery atherosclerosis can be broadly compartmentalized into four distinct clinical scenarios based upon the individual patient’s history, examination, and anatomic imaging findings: asymptomatic and symptomatic extracranial carotid stenosis, intracranial atherosclerosis, and extracranial vertebral artery atherosclerotic disease. This review provides a framework for clinicians evaluating and treating such patients. Recent Findings: Intensive medical therapy achieves low rates of stroke and death in asymptomatic carotid stenosis. Evidence indicates that patients with severe symptomatic carotid stenosis should undergo carotid revascularization sooner rather than later and that the risk of stroke or death is lower using carotid endarterectomy than with carotid stenting. Specific to stenting, the risk of stroke or death is greatest among older patients and women. Continuous vascular risk factor optimization via sustained behavioral modifications and intensive medical therapy is the mainstay for stroke prevention in the setting of intracranial and vertebral artery origin atherosclerosis. Summary: Lifelong vascular risk factor optimization via sustained behavioral modifications and intensive medical therapy are the key elements to reduce future stroke risk in the setting of large artery atherosclerosis. When considering a revascularization procedure for carotid stenosis, patient demographics, comorbidities, and the periprocedural risks of stroke and death should be carefully considered. PMID:28157748

Numerical Cerebrospinal System Modeling in Fluid-Structure Interaction.

PubMed

Garnotel, Simon; Salmon, Stéphanie; Balédent, Olivier

2018-01-01

Cerebrospinal fluid (CSF) stroke volume in the aqueduct is widely used to evaluate CSF dynamics disorders. In a healthy population, aqueduct stroke volume represents around 10% of the spinal stroke volume while intracranial subarachnoid space stroke volume represents 90%. The amplitude of the CSF oscillations through the different compartments of the cerebrospinal system is a function of the geometry and the compliances of each compartment, but we suspect that it could also be impacted be the cardiac cycle frequency. To study this CSF distribution, we have developed a numerical model of the cerebrospinal system taking into account cerebral ventricles, intracranial subarachnoid spaces, spinal canal and brain tissue in fluid-structure interactions. A numerical fluid-structure interaction model is implemented using a finite-element method library to model the cerebrospinal system and its interaction with the brain based on fluid mechanics equations and linear elasticity equations coupled in a monolithic formulation. The model geometry, simplified in a first approach, is designed in accordance with realistic volume ratios of the different compartments: a thin tube is used to mimic the high flow resistance of the aqueduct. CSF velocity and pressure and brain displacements are obtained as simulation results, and CSF flow and stroke volume are calculated from these results. Simulation results show a significant variability of aqueduct stroke volume and intracranial subarachnoid space stroke volume in the physiological range of cardiac frequencies. Fluid-structure interactions are numerous in the cerebrospinal system and difficult to understand in the rigid skull. The presented model highlights significant variations of stroke volumes under cardiac frequency variations only.

Necessity of early-stage verticalization in patients with brain and spinal cord injuries: Preliminary study.

PubMed

Daunoraviciene, Kristina; Adomaviciene, Ausra; Svirskis, Donatas; Griškevičius, Julius; Juocevicius, Alvydas

2018-05-18

Integration of the verticalization robot, Erigo, with functional electric stimulation and passive leg movements in the postacute rehabilitation of neurological patients could reduce the risk of secondary complications and improve functional outcomes (i.e. orthostatic hypotension, postural control and walking ability). The aim of this study was to estimate and quantify changes in the postacute stage, mainly related to heart rate and blood pressure in functional recovery, postural parameters, walking ability and psychoemotional reactions, during training using the verticalization robot Erigo. Six patients [three suffering from a stroke (ST) and three with spinal cord injuries (SCI)] participated in 10 sessions of physical therapy with the verticalization robot during primary inpatient rehabilitation. Functional state changes were assessed using clinical tests before and after the treatment, and the loading tolerance during Erigo training was noted. In early rehabilitation, Erigo training was safe and effective at improving orthostatic tolerance, posture and positive emotional reactions in both the ST and SCI patients (P< 0.05). In addition, advanced technologies were more effective at boosting the orthostatic tolerance in SCI patients, while they were more effective at increasing the dynamic balance and walking ability in ST patients (P< 0.05).

A pathway in the brainstem for roll-tilt of the subjective visual vertical: evidence from a lesion-behavior mapping study.

PubMed

Baier, Bernhard; Thömke, Frank; Wilting, Janine; Heinze, Caroline; Geber, Christian; Dieterich, Marianne

2012-10-24

The perceived subjective visual vertical (SVV) is an important sign of a vestibular otolith tone imbalance in the roll plane. Previous studies suggested that unilateral pontomedullary brainstem lesions cause ipsiversive roll-tilt of SVV, whereas pontomesencephalic lesions cause contraversive roll-tilts of SVV. However, previous data were of limited quality and lacked a statistical approach. We therefore tested roll-tilt of the SVV in 79 human patients with acute unilateral brainstem lesions due to stroke by applying modern statistical lesion-behavior mapping analysis. Roll-tilt of the SVV was verified to be a brainstem sign, and for the first time it was confirmed statistically that lesions of the medial longitudinal fasciculus (MLF) and the medial vestibular nucleus are associated with ipsiversive tilt of the SVV, whereas contraversive tilts are associated with lesions affecting the rostral interstitial nucleus of the MLF, the superior cerebellar peduncle, the oculomotor nucleus, and the interstitial nucleus of Cajal. Thus, these structures constitute the anatomical pathway in the brainstem for verticality perception. Present data indicate that graviceptive otolith signals present a predominant role in the multisensory system of verticality perception.

Verification of a Non-Hydrostatic Dynamical Core Using Horizontally Spectral Element Vertically Finite Difference Method: 2D Aspects

DTIC Science & Technology

2014-04-01

hydrostatic pressure vertical coordinate, which are the same as those used in the Weather Research and Forecasting ( WRF ) model, but a hybrid sigma...hydrostatic pressure vertical coordinate, which are the 33 same as those used in the Weather Research and Forecasting ( WRF ) model, but a hybrid 34 sigma...Weather Research and Forecasting 79 ( WRF ) Model. The Euler equations are in flux form based on the hydrostatic pressure vertical 80 coordinate. In

Long stroke jar bumper sub with safety sleeve

DOE Office of Scientific and Technical Information (OSTI.GOV)

Downen, J.L.; Sutliff, W.N.

1981-04-14

A hydraulic jar apparatus to be disposed in a drilling string embodying inner and outer telescopically arranged elements. Overlapping portions of the elements provide an annual chamber confining an operating liquid by an annular seal fixed to the outer element at the lower end of the chamber and an annular polly pack seal fixed to the outer element at the upper end of the chamber. A piston is extended radially from the inner element into the chamber and the chamber is divided by a cylinder on the outer element into low and high pressure sections. Impact shoulders are provided onmore » the elements in axially opposed relation to produce a jarring blow and the elements are telescopically coupled by a hexagonal spline sub assembly.« less

Distributed support modelling for vertical track dynamic analysis

NASA Astrophysics Data System (ADS)

Blanco, B.; Alonso, A.; Kari, L.; Gil-Negrete, N.; Giménez, J. G.

2018-04-01

The finite length nature of rail-pad supports is characterised by a Timoshenko beam element formulation over an elastic foundation, giving rise to the distributed support element. The new element is integrated into a vertical track model, which is solved in frequency and time domain. The developed formulation is obtained by solving the governing equations of a Timoshenko beam for this particular case. The interaction between sleeper and rail via the elastic connection is considered in an analytical, compact and efficient way. The modelling technique results in realistic amplitudes of the 'pinned-pinned' vibration mode and, additionally, it leads to a smooth evolution of the contact force temporal response and to reduced amplitudes of the rail vertical oscillation, as compared to the results from concentrated support models. Simulations are performed for both parametric and sinusoidal roughness excitation. The model of support proposed here is compared with a previous finite length model developed by other authors, coming to the conclusion that the proposed model gives accurate results at a reduced computational cost.

Project VeSElkA: results of abundance analysis for HD 53929 and HD 63975

NASA Astrophysics Data System (ADS)

Ndiaye, M. L.; LeBlanc, F.; Khalack, V.

2018-03-01

Project VeSElkA (Vertical Stratification of Element Abundances) has been initiated with the aim to detect and study the vertical stratification of element abundances in the atmosphere of chemically peculiar stars. Abundance stratification occurs in hydrodynamically stable stellar atmospheres due to the migration of the elements caused by atomic diffusion. Two HgMn stars, HD 53929 and HD 63975 were selected from the VeSElkA sample and analysed with the aim to detect some abundance peculiarities employing the ZEEMAN2 code. We present the results of abundance analysis of HD 53929 and HD 63975 observed recently with the spectropolarimeter ESPaDOnS at Canada-France-Hawaii Telescope. Evidence of phosphorus vertical stratification was detected in the atmosphere of these two stars. In both cases, phosphorus abundance increases strongly towards the superficial layers. The strong overabundance of Mn found in stellar atmosphere of both stars confirms that they are HgMn type stars.

Calculation of cogging force in a novel slotted linear tubular brushless permanent magnet motor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Z.Q.; Hor, P.J.; Howe, D.

1997-09-01

There is an increasing requirement for controlled linear motion over short and long strokes, in the factory automation and packaging industries, for example. Linear brushless PM motors could offer significant advantages over conventional actuation technologies, such as motor driven cams and linkages and pneumatic rams--in terms of efficiency, operating bandwidth, speed and thrust control, stroke and positional accuracy, and indeed over other linear motor technologies, such as induction motors. Here, a finite element/analytical based technique for the prediction of cogging force in a novel topology of slotted linear brushless permanent magnet motor has been developed and validated. The various forcemore » components, which influence cogging are pre-calculated by the finite element analysis of some basic magnetic structures, facilitate the analytical synthesis of the resultant cogging force. The technique can be used to aid design for the minimization of cogging.« less

Simulation of radiation from lightning return strokes - The effects of tortuosity

NASA Technical Reports Server (NTRS)

Levine, D. M.; Meneghini, R.

1978-01-01

A Monte Carlo simulation has been developed for the electromagnetic fields radiated from a tortuous lightning channel. This was done using a piecewise linear model for the channel and employing for each element the field radiated by a traveling wave on an arbitrarily oriented filament over a conducting plane. The simulation reproduces experimental data reasonably well and has been used to study the effects of tortuosity on the fields radiated by return strokes. Tortuosity can significantly modify the radiated waveform, tending to render it less representative of the current pulse and more nearly unipolar than one would expect based on the theory for a long straight channel. In the frequency domain the effect of tortuosity is an increase in high frequency energy as compared with an equivalent straight channel. The extent of this increase depends on the mean length of the elements comprising the channel and can be significant.

VIEW OF PDP TANK TOP AT LEVEL 0’, WITH VERTICAL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF PDP TANK TOP AT LEVEL 0’, WITH VERTICAL ELEMENTS IN BACKGROUND AND PART OF SHEAVE RACK ABOVE THE TANK, LOOKING NORTH - Physics Assembly Laboratory, Area A/M, Savannah River Site, Aiken, Aiken County, SC

The principal motions involved in the coupling mechanism of the recovery stroke of the myosin motor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mesentean, Sidonia; Koppole, Sampath; Smith, Jeremy C

2006-12-01

Muscle contraction is driven by a cycle of conformational changes in the myosin II head. After myosin binds ATP and releases from the actin fibril, myosin prepares for the next power stroke by rotating back the converter domain that carries the lever arm by {approx}60 degrees. This recovery stroke is coupled to the activation of myosin's ATPase by a mechanism that is essential for an efficient motor cycle. The mechanics of this coupling have been proposed to occur via two distinct and successive motions of the two helices that hold the converter domain: in a first phase a see-saw motionmore » of the relay helix, followed by a piston/seesaw motion of the SH1 helix in a second phase. To test this model, we have determined the principal motions of these structural elements during equilibrium molecular dynamics simulations of the crystallographic end states of the recovery stroke by using Principal Component Analysis. This reveals that the only principal motions of these two helices that make a large amplitude contribution towards the conformational change of the recovery stroke are indeed the predicted seesaw and piston motions.« less

A NASTRAN model of a large flexible swing-wing bomber. Volume 2: NASTRAN model development-horizontal stabilzer, vertical stabilizer and nacelle structures

NASA Technical Reports Server (NTRS)

Mock, W. D.; Latham, R. A.; Tisher, E. D.

1982-01-01

The NASTRAN model plans for the horizontal stabilizer, vertical stabilizer, and nacelle structure were expanded in detail to generate the NASTRAN model for each of these substructures. The grid point coordinates were coded for each element. The material properties and sizing data for each element were specified. Each substructure model was thoroughly checked out for continuity, connectivity, and constraints. These substructures were processed for structural influence coefficients (SIC) point loadings and the deflections were compared to those computed for the aircraft detail models. Finally, a demonstration and validation processing of these substructures was accomplished using the NASTRAN finite element program installed at NASA/DFRC facility.

A Discontinuous Galerkin Method for Parabolic Problems with Modified hp-Finite Element Approximation Technique

NASA Technical Reports Server (NTRS)

Kaneko, Hideaki; Bey, Kim S.; Hou, Gene J. W.

2004-01-01

A recent paper is generalized to a case where the spatial region is taken in R(sup 3). The region is assumed to be a thin body, such as a panel on the wing or fuselage of an aerospace vehicle. The traditional h- as well as hp-finite element methods are applied to the surface defined in the x - y variables, while, through the thickness, the technique of the p-element is employed. Time and spatial discretization scheme based upon an assumption of certain weak singularity of double vertical line u(sub t) double vertical line 2, is used to derive an optimal a priori error estimate for the current method.

The implementation of integrated care: the empirical validation of the Development Model for Integrated Care

PubMed Central

2011-01-01

Background Integrated care is considered as a strategy to improve the delivery, efficiency, client outcomes and satisfaction rates of health care. To integrate the care from multiple providers into a coherent client-focused service, a large number of activities and agreements have to be implemented like streamlining information flows and patient transfers. The Development Model for Integrated care (DMIC) describes nine clusters containing in total 89 elements that contribute to the integration of care. We have empirically validated this model in practice by assessing the relevance, implementation and plans of the elements in three integrated care service settings in The Netherlands: stroke, acute myocardial infarct (AMI), and dementia. Methods Based on the DMIC, a survey was developed for integrated care coordinators. We invited all Dutch stroke and AMI-services, as well as the dementia care networks to participate, of which 84 did (response rate 83%). Data were collected on relevance, presence, and year of implementation of the 89 elements. The data analysis was done by means of descriptive statistics, Chi Square, ANOVA and Kruskal-Wallis H tests. Results The results indicate that the integrated care practice organizations in all three care settings rated the nine clusters and 89 elements of the DMIC as highly relevant. The average number of elements implemented was 50 ± 18, 42 ± 13, and 45 ± 22 for stroke, acute myocardial infarction, and dementia care services, respectively. Although the dementia networks were significantly younger, their numbers of implemented elements were comparable to those of the other services. The analyses of the implementation timelines showed that the older integrated care services had fewer plans for further implementation than the younger ones. Integrated care coordinators stated that the DMIC helped them to assess their integrated care development in practice and supported them in obtaining ideas for expanding their integrated care activities. Conclusions Although the patient composites and the characteristics of the 84 participating integrated care services differed considerably, the results confirm that the clusters and the vast majority of DMIC elements are relevant to all three groups. Therefore, the DMIC can serve as a general quality management tool for integrated care. Applying the model in practice can help in steering further implementations as well as the development of new integrated care practices. PMID:21801428

The implementation of integrated care: the empirical validation of the Development Model for Integrated care.

PubMed

Minkman, Mirella M N; Vermeulen, Robbert P; Ahaus, Kees T B; Huijsman, Robbert

2011-07-30

Integrated care is considered as a strategy to improve the delivery, efficiency, client outcomes and satisfaction rates of health care. To integrate the care from multiple providers into a coherent client-focused service, a large number of activities and agreements have to be implemented like streamlining information flows and patient transfers. The Development Model for Integrated care (DMIC) describes nine clusters containing in total 89 elements that contribute to the integration of care. We have empirically validated this model in practice by assessing the relevance, implementation and plans of the elements in three integrated care service settings in The Netherlands: stroke, acute myocardial infarct (AMI), and dementia. Based on the DMIC, a survey was developed for integrated care coordinators. We invited all Dutch stroke and AMI-services, as well as the dementia care networks to participate, of which 84 did (response rate 83%). Data were collected on relevance, presence, and year of implementation of the 89 elements. The data analysis was done by means of descriptive statistics, Chi Square, ANOVA and Kruskal-Wallis H tests. The results indicate that the integrated care practice organizations in all three care settings rated the nine clusters and 89 elements of the DMIC as highly relevant. The average number of elements implemented was 50 ± 18, 42 ± 13, and 45 ± 22 for stroke, acute myocardial infarction, and dementia care services, respectively. Although the dementia networks were significantly younger, their numbers of implemented elements were comparable to those of the other services. The analyses of the implementation timelines showed that the older integrated care services had fewer plans for further implementation than the younger ones. Integrated care coordinators stated that the DMIC helped them to assess their integrated care development in practice and supported them in obtaining ideas for expanding their integrated care activities. Although the patient composites and the characteristics of the 84 participating integrated care services differed considerably, the results confirm that the clusters and the vast majority of DMIC elements are relevant to all three groups. Therefore, the DMIC can serve as a general quality management tool for integrated care. Applying the model in practice can help in steering further implementations as well as the development of new integrated care practices.

Heating equipment installation system

DOEpatents

Meuschke, Robert E.; Pomaibo, Paul P.

1991-01-01

A method for installing a heater unit assembly (52, 54) in a reactor pressure vessel (2) for performance of an annealing treatment on the vessel (2), the vessel (2) having a vertical axis, being open at the top, being provided at the top with a flange (6) having a horizontal surface, and being provided internally, at a location below the flange (6), with orientation elements (8) which are asymmetrical with respect to the vertical axis, by the steps of: providing an orientation fixture (10) having an upwardly extending guide member (18) and orientation elements (14, 16) and installing the orientation fixture (10) in the vessel (2) so that the orientation elements (14,16) of the orientation fixture (10) mate with the orientation elements (8) of the pressure vessel (2) in order to establish a defined position of the orientation fixture (10) in the pressure vessel (2), and so that the guide member (18) projects above the pressure vessel (2) flange (6); placing a seal ring (30) in a defined position on the pressure vessel (2) flange (6) with the aid of the guide member (18); mounting at least one vertical, upwardly extending guide stud (40) upon the seal ring (30); withdrawing the orientation fixture (10) from the pressure vessel (2); and moving the heater unit assembly (52,54) vertically downwardly into the pressure vessel (2) while guiding the heater unit assembly (52,54) along a path with the aid of the guide stud (40).

The decline of soil due to the pile of highway project Medan-Kualanamu (STA 35 + 901) with the finite element method

NASA Astrophysics Data System (ADS)

Hastuty, I. P.; Roesyanto; Sihite, A. B.

2018-02-01

Consolidation is the process of discharge of water from the ground through the pore cavity. Consolidation occurs in soft soil or unstable soil that allows an improvement in order to make the soil more stable. The method of using Prefabricated Vertical Drain (PVD) is one way to improve unstable soils. PVD works like a sand column that can drain water vertically. This study aims to determine the decrease, pore water pressure and soil consolidation rate with Prefabricated Vertical Drain (PVD) and without PVD analytically and using finite element method that affect the duration of soil decline to reach 90% consolidation or in other words soil does not decline anymore. Based on the analytical calculation, the decrease obtained is equal to 0.47 m meanwhile the result of calculation using finite element method is 0.45 m. The consolidation rate obtained from analytical calculation is 19 days with PVD and 115 days without PVD. The consolidation rate obtained from finite element method is 63 days with PVD and 110 days without PVD. And the pore water pressure is 0.92 KN/m2.

Design and evaluation of NEUROBike: a neurorehabilitative platform for bedridden post-stroke patients.

PubMed

Monaco, Vito; Galardi, Giuseppe; Coscia, Martina; Martelli, Dario; Micera, Silvestro

2012-11-01

Over the past decades, a large number of robotic platforms have been developed which provide rehabilitative treatments aimed at recovering walking abilities in post-stroke patients. Unfortunately, they do not significantly influence patients' performance after three months from the accident. One of the main reasons underlying this result seems to be related to the time of intervention. Specifically, although experimental evidences suggest that early (i.e., first days after the injury) and intense neuro-rehabilitative treatments can significantly favor the functional recovery of post-stroke patients, robots require patients to be verticalized. Consequently, this does not allow them to be treated immediately after the trauma. This paper introduces a new robotic platform, named NEUROBike, designed to provide neuro-rehabilitative treatments to bedridden patients. It was designed to provide an early and well-addressed rehabilitation therapy, in terms of kinesiology, efforts, and fatigue, accounting for exercises functionally related to daily motor tasks. For this purpose, kinematic models of leg-joint angular excursions during both walking and sit-to-stand were developed and implemented in control algorithms leading both passive and active exercises. Finally, a set of pilot tests was carried out to evaluate the performance of the robotic platform on healthy subjects.

Vertical Transmission of the Retrotransposable Elements R1 and R2 during the Evolution of the Drosophila Melanogaster Species Subgroup

PubMed Central

Eickbush, D. G.; Eickbush, T. H.

1995-01-01

R1 and R2 are non-long-terminal repeat retrotransposable elements that insert into specific sequences of insect 28S ribosomal RNA genes. These elements have been extensively described in Drosophila melanogaster. To determine whether these elements have been horizontally or vertically transmitted, we characterized R1 and R2 elements from the seven other members of the melanogaster species subgroup by genomic blotting and nucleotide sequencing. Each species was found to have homogeneous families of R1 and R2 elements with the exception of erecta and orena, which have no R2 elements. The DNA sequences of multiple R1 and R2 copies from each species indicated nucleotide divergence within each species averaged only 0.48% for R1 and 0.35% for R2, well below the level of divergence among the species. Most copies of R1 and R2 (40 of 47) sequenced from the seven species were potentially functional, as indicated by the absence of premature termination codons or translational frameshifts that would destroy the open reading frame of the element. The sequence relationships of both the R1 and R2 elements from the various members of the melanogaster subgroup closely followed that of the species phylogeny, suggesting that R1 and R2 have been stably maintained by vertical transmission since the origin of this species subgroup 17-20 million years ago. The remarkable stability of R1 and R2, compared to what has been suggested for transposable elements that insert at multiple locations in these same species, may be due to their unique specificity for sites in the rRNA gene locus. Under low copy number conditions, when it is essential for any mobile element to transpose, the insertion specificities of R1 and R2 ensure uniform developmentally regulated target sites that can be occupied with little or no detrimental effect on the host. PMID:7713424

Efficient Computation of Atmospheric Flows with Tempest: Development of Next-Generation Climate and Weather Prediction Algorithms at Non-Hydrostatic Scales

NASA Astrophysics Data System (ADS)

Guerra, J. E.; Ullrich, P. A.

2015-12-01

Tempest is a next-generation global climate and weather simulation platform designed to allow experimentation with numerical methods at very high spatial resolutions. The atmospheric fluid equations are discretized by continuous / discontinuous finite elements in the horizontal and by a staggered nodal finite element method (SNFEM) in the vertical, coupled with implicit/explicit time integration. At global horizontal resolutions below 10km, many important questions remain on optimal techniques for solving the fluid equations. We present results from a suite of meso-scale test cases to validate the performance of the SNFEM applied in the vertical. Internal gravity wave, mountain wave, convective, and Cartesian baroclinic instability tests will be shown at various vertical orders of accuracy and compared with known results.

Development of a high-frequency and large-stroke fatigue testing system for rubber

NASA Astrophysics Data System (ADS)

Chen, Gang; Wu, Hao; Gao, Jianwen; Lin, Qiang

2017-04-01

The limited capabilities of current fatigue testing machines have resulted in studies on the fatigue behavior of rubber under large-displacement amplitude and high frequency being very sparse. In this study, a fatigue testing system that can carry out large-displacement amplitude and high-frequency fatigue tests on rubber was developed using a moving magnet voice coil motor (MMVCM) actuator, with finite element analysis applied to analyze the thrust of the MMVCM actuator. The results of a series of cyclic tension tests conducted on vulcanized natural rubber specimens using the developed fatigue testing system verify that it has high precision, low noise, large-stroke, and high-frequency characteristics. Further, the load frame with the developed MMVCM actuator is feasible for material testing, especially for large-stroke and high-frequency fatigue tests.

Use of Rare Earth Elements in investigations of aeolian processes

USDA-ARS?s Scientific Manuscript database

The representation of the dust cycle in atmospheric circulation models hinges on an accurate parameterization of the vertical dust flux at emission. However, existing parameterizations of the vertical dust flux vary substantially in their scaling with wind friction velocity, require input parameters...

Particulate Trace Element Cycling in a Diatom Bloom at Station ALOHA

NASA Astrophysics Data System (ADS)

Weisend, R.; Morton, P. L.; Landing, W. M.; Fitzsimmons, J. N.; Hayes, C. T.; Boyle, E. A.

2014-12-01

Phytoplankton in oligotrophic marine deserts depend on remote sources to supply trace nutrients. To examine these sources, marine particulate matter samples from the central North Pacific (Station ALOHA) were collected during the July-August 2012 HOE-DYLAN cruises and analyzed for a suite of trace (e.g., Fe, Mn) and major (e.g. Al, P) elements. Daily surface SPM samples were examined for evidence of atmospheric deposition and biological uptake, while five vertical profiles were examined for evidence of surface vertical export and subsurface horizontal transport from nearby sources (e.g., margin sediments, hydrothermal plumes). Maxima in surface particulate P (a biological tracer) corresponded with a diatom bloom, and surprisingly also coincided with maxima in particulate Al (typically a tracer for lithogenic inputs). The surface particulate Al distributions likely result from the adsorption of dissolved Al onto diatom silica frustules, not from atmospheric dust deposition. In addition, a subsurface maximum in particulate Al and P was observed four days later at 75m, possibly resulting from vertical export of the surface diatom bloom. The distributions of other bioactive trace elements (e.g. Cd, Co, Cu) will be presented in the context of the diatom bloom and other biological, chemical and physical features. A second, complementary poster is also being presented which examines the cycling of trace elements in lithogenic particles (Morton et al., "Trace Element Cycling in Lithogenic Particles at Station ALOHA").

Ischemic Heart Disease and Stroke in Relation to Blood DNA Methylation

PubMed Central

Baccarelli, Andrea; Wright, Robert; Bollati, Valentina; Litonjua, Augusto; Zanobetti, Antonella; Tarantini, Letizia; Sparrow, David; Vokonas, Pantel; Schwartz, Joel

2013-01-01

Background Epigenetic features such as DNA hypomethylation have been associated with conditions related to cardiovascular risk. We evaluated whether lower blood DNA methylation in heavily methylated repetitive sequences predicts the risk of ischemic heart disease and stroke. Methods We quantified blood DNA methylation of LINE-1 repetitive elements through PCR-pyrosequencing in 712 elderly individuals from the Boston-area Normative Aging Study. We estimated risk-factor adjusted relative risks (RRs) for ischemic heart disease and stroke at baseline (242 prevalent cases); as well as in incidence (44 new cases; median follow-up, 63 months); and subsequent mortality from ischemic heart disease (86 deaths; median follow-up, 75 months). Results Blood LINE-1 hypomethylation was associated with baseline ischemic heart disease (RR=2.1 [95% confidence interval = 1.2 to 4.0] for lowest vs. highest methylation quartile) and for stroke (2.5 [0.9 to 7.5]). Among participants free of baseline disease, individuals with methylation below the median also had higher risk of developing ischemic heart disease (4.0 [1.8 to 8.9]) or stroke (5.7 [0.8 to 39.5]). In the entire cohort, persons with methylation below the median had higher mortality from ischemic heart disease (3.3 [1.3 to 8.4]) and stroke (2.8 [0.6 to 14.3]). Total mortality was also increased (2.0 [1.2 to 3.3]). These results were confirmed in additional regression models using LINE-1 methylation as a continuous variable. Conclusions Subjects with prevalent IHD and stroke exhibited lower LINE-1 methylation. In longitudinal analyses, persons with lower LINE-1 methylation were at higher risk for incident ischemic heart disease and stroke, and for total mortality. PMID:20805753

The principal motions involved in the coupling mechanism of the recovery stroke of the myosin motor.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mesentean, Sidonia; Koppole, Sampath; Smith, Jeremy C

2007-03-01

Muscle contraction is driven by a cycle of conformational changes in the myosin II head. After myosin binds ATP and releases from the actin fibril, myosin prepares for the next power stroke by rotating back the converter domain that carries the lever arm by 60{sup o}. This recovery stroke is coupled to the activation of myosin ATPase by a mechanism that is essential for an efficient motor cycle. The mechanics of this coupling have been proposed to occur via two distinct and successive motions of the two helices that hold the converter domain: in a first phase a seesaw motionmore » of the relay helix, followed by a piston-like motion of the SH1 helix in a second phase. To test this model, we have determined the principal motions of these structural elements during equilibrium molecular dynamics simulations of the crystallographic end states of the recovery-stroke by using principal component analysis. This reveals that the only principal motions of these two helices that make a large-amplitude contribution towards the conformational change of the recovery stroke are indeed the predicted seesaw and piston motions. Moreover, the results demonstrate that the seesaw motion of the relay helix dominates in the dynamics of the pre-recovery stroke structure, but not in the dynamics of the post-recovery stroke structure, and vice versa for the piston motion of the SH1 helix. This is consistent with the order of the proposed two-phase model for the coupling mechanism of the recovery stroke. Molecular movies of these principal motions are available at http://www.iwr.uni-heidelberg.de/groups/biocomp/fischer.« less

Neuronal PirB Upregulated in Cerebral Ischemia Acts as an Attractive Theranostic Target for Ischemic Stroke.

PubMed

Wang, Jie; Zhang, Ying; Xia, Jing; Cai, Tingting; Du, Jiawei; Chen, Jinpeng; Li, Ping; Shen, Yuqing; Zhang, Aifeng; Fu, Bo; Gao, Xueren; Miao, Fenqin; Zhang, Jianqiong; Teng, Gaojun

2018-01-29

Ischemic stroke is a complex disease with multiple etiologies and clinical manifestations. Paired immunoglobulin-like receptor B (PirB), which is originally thought to function exclusively in the immune system, is now also known to be expressed by neurons. A growing number of studies indicate that PirB can inhibit neurite outgrowth and restrict neuronal plasticity. The aim of the study is to investigate whether PirB can be an attractive theranostic target for ischemic stroke. First, we investigated the spatial-temporal expression of PirB in multiple ischemic stroke models, including transient middle cerebral artery occlusion, photothrombotic cerebral cortex ischemia, and the neuronal oxygen glucose deprivation model. Then, anti-PirB immunoliposome nanoprobe was developed by thin-film hydration method and investigated its specific targeting in vitro and in vivo. Finally, soluble PirB ectodomain (sPirB) protein delivered by polyethylene glycol-modified nanoliposome was used as a therapeutic reagent for ischemic stroke by blocking PirB binding to its endogenous ligands. These results showed that PirB was significantly upregulated after cerebral ischemic injury in ischemic stroke models. Anti-PirB immunoliposome nanoprobe was successfully developed and specifically bound to PirB in vitro. There was accumulation of anti-PirB immunoliposome nanoprobe in the ischemic hemisphere in vivo. Soluble PirB ectodomains remarkably improved ischemic stroke model recovery by liposomal delivery system. These data indicated that PirB was a significant element in the pathological process of cerebral ischemia. Therefore, PirB may act as a novel theranostic target for ischemic stroke. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Thinking About Better Speech: Mental Practice for Stroke-Induced Motor Speech Impairments

PubMed Central

Page, Stephen J.; Harnish, Stacy

2012-01-01

Background Mental practice (MP) is a mind-body technique in which physical movements are cognitively rehearsed. It has shown efficacy in reducing the severity of a number of neurological impairments. Aims In the present review, we highlight recent developments in MP research, and the basis for MP use after stroke-induced motor speech disorders. Main Contribution In this review, we: (a) propose a novel conceptual model regarding the development of learned nonuse in people with motor speech impairments; (b) review the rationale and efficacy of MP for reducing the severity of stroke-induced impairments; (c) review evidence demonstrating muscular and neural activations during and following MP use; (d) review evidence showing that MP increases skill acquisition, use, and function in stroke; (e) review literature regarding neuroplasticity after stroke, including MP-induced neuroplasticity and the neural substrates underlying motor and language reacquisition; and (f) based on the above, review the rationale and clinical application of MP for stroke-induced motor speech impairments. Conclusions Support for MP use includes decades of MP neurobiological and behavioral efficacy data in a number of populations. Most recently, these data have expanded to the application of MP in neurological populations. Given increasingly demanding managed care environments, efficacious strategies that can be easily administered are needed. We also encounter clinicians who aspire to use MP, but their protocols do not contain several of the elements shown to be fundamental to effective MP implementation. Given shortfalls of some conventional aphasia and motor speech rehabilitative techniques, and uncertainty regarding optimal MP implementation, this paper introduces the neurophysiologic bases for MP, the evidence for MP use in stroke rehabilitation, and discusses its applications and considerations in patients with stroke-induced motor speech impairments. PMID:22308050

Differentiation characteristics and source analysis of heavy metals in typical brown soil under different vegetation

NASA Astrophysics Data System (ADS)

Dong, Zhicheng; Zhang, Lina; Li, Xueshuang; Lv, Shuangyan; He, Shijie; Liu, Ying; Ma, Xuanxuan

2017-08-01

Anomalous enrichment of soil elements (especially heavy metals) has aroused popular attention in China. In order to discuss distribution characteristics and analyze sources of elements in brown soil, field investigation and sample collection were carried out under different vegetation (cherry, apple, bamboos and pine) in Qixia, a typical apple production base in China. Element contents, pH, electrical conductivity (EC) and magnetic susceptibility (MS) were tested. Results showed that element concentrations were about roughly 2.48 times as China’s background values, while significantly lower than the class ii of National soil Environment Quality Standard (Ni excepted). Meanwhile, vertical distribution and accumulation characteristics of elements in typical brown soil were significantly different under different vegetation. In detail, elements (Zn excepted) of Pine soil accumulated in surface, while they (Cd, Arsenic excepted) increased with depth under other vegetation. Moreover, pH and EC changed like elements, while MS was exactly opposite. It was found that those differences above were mainly caused by human activities (such as improper use of fertilizer, pesticide and inadequate use of organic fertilizer, etc.). Additionally, differences in composition and decomposition rate of vegetation litter also resulted in vertical differentiations of soil elements under different vegetation.

Experimental Observations of Vortex Ring Interaction with the Fluid Adjacent to a Surface.

DTIC Science & Technology

1983-10-01

minute. The water enters the inlet tank from a distribution manifold pipe and rises vertically through a 15 cm. thick plastic sponge. The flow then passes...parts exposed to water are made from PVC plastic to resist corrosion. The generator was designed to have interchangeable parts which allow the generation...of vortex rings over a range of caracteristics . The motor speed is continuously variable up to a speed of 7400 rpm. Cams with stroke lengths of 0.64

High-Isolation Low Cross-Polarization Phased-Array Antenna for MPAR Application

NASA Astrophysics Data System (ADS)

Saeidi-Manesh, Hadi; Karimkashi, Shaya; Zhang, Guifu; Doviak, Richard J.

2017-12-01

The design and analysis of 12 × 12-element planar array of a dual-polarized aperture-coupled microstrip patch antenna operating in the frequency band of 2.7 GHz to 3.0 GHz for multifunction applications are presented. High-isolation between horizontal and vertical polarization ports and low cross-polarization are achieved through an aperture-coupled feed. The reflection coefficient and the isolation of horizontal and vertical ports at different scan angles are examined. The array antenna is fabricated and its radiation patterns are measured in the far-field and near-field chambers. The embedded element pattern of designed element is measured in the near-field chamber and is used for calculating the array scanning radiation pattern.

Modelling the oscillations of the thermocline in a lake by means of a fully consistent and conservative 3D finite-element model with a vertically adaptive mesh

NASA Astrophysics Data System (ADS)

Delandmeter, Philippe; Lambrechts, Jonathan; Vallaeys, Valentin; Naithani, Jaya; Remacle, Jean-François; Legat, Vincent; Deleersnijder, Eric

2017-04-01

Vertical discretisation is crucial in the modelling of lake thermocline oscillations. For finite element methods, a simple way to increase the resolution close to the oscillating thermocline is to use vertical adaptive coordinates. With an Arbitrary Lagrangian-Eulerian (ALE) formulation, the mesh can be adapted to increase the resolution in regions with strong shear or stratification. In such an application, consistency and conservativity must be strictly enforced. SLIM 3D, a discontinuous-Galerkin finite element model for shallow-water flows (www.climate.be/slim, e.g. Kärnä et al., 2013, Delandmeter et al., 2015), was designed to be strictly consistent and conservative in its discrete formulation. In this context, special care must be paid to the coupling of the external and internal modes of the model and the moving mesh algorithm. In this framework, the mesh can be adapted arbitrarily in the vertical direction. Two moving mesh algorithms were implemented: the first one computes an a-priori optimal mesh; the second one diffuses vertically the mesh (Burchard et al., 2004, Hofmeister et al., 2010). The criteria used to define the optimal mesh and the diffusion function are related to a suitable measure of shear and stratification. We will present in detail the design of the model and how the consistency and conservativity is obtained. Then we will apply it to both idealised benchmarks and the wind-forced thermocline oscillations in Lake Tanganyika (Naithani et al. 2002). References Tuomas Kärnä, Vincent Legat and Eric Deleersnijder. A baroclinic discontinuous Galerkin finite element model for coastal flows, Ocean Modelling, 61:1-20, 2013. Philippe Delandmeter, Stephen E Lewis, Jonathan Lambrechts, Eric Deleersnijder, Vincent Legat and Eric Wolanski. The transport and fate of riverine fine sediment exported to a semi-open system. Estuarine, Coastal and Shelf Science, 167:336-346, 2015. Hans Burchard and Jean-Marie Beckers. Non-uniform adaptive vertical grids in one-dimensional numerical ocean models. Ocean Modelling, 6:51-81, 2004. Richard Hofmeister, Hans Burchard and Jean-Marie Beckers. Non-uniform adaptive vertical grids for 3d numerical ocean models. Ocean Modelling, 33:70-86, 2010. Jaya Naithani, Eric Deleersnijder and Pierre-Denis Plisnier. Origin of intraseasonal variability in Lake Tanganyika. Geophysical Research Letters, 29(23), doi:10.1029/2002GL015843, 2002.

Somnolence and Stuttering as the Primary Manifestations of a Midbrain Stroke

PubMed Central

Karakis, Ioannis; Ellenstein, Aviva; Roselló, Gemma R; Romero, José R

2008-01-01

Background: Stroke can occasionally manifest with non-lateralizing findings such as somnolence and stuttering. We describe a case and discuss the anatomical and physiological implications of this rare combination of symptoms. Case report: A 51-year-old woman presented with 3 days of “feeling drunk”. She could further specify her symptoms as blurry vision, slurred speech, and gait instability. She had a history of hypertension and hyperlipidemia. Her examination at presentation was remarkable only for marked somnolence. Over the next several hours she developed mild upgaze limitation and vertical nystagmus. Non-enhanced computed tomography of the brain was normal. Brain magnetic resonance imaging (MRI) revealed a 5 mm acute infarct in the caudal midbrain. The first week the patient remained somnolent and manifested marked stuttering. The patient improved gradually with speech therapy. Conclusion: Strokes affecting the diencephalic-mesencephalic junction can manifest with stuttering. Defective projections of the reticular formation to the supplementary motor area, damaged extrapyramidal circuits, and/or aberrant propioceptive feedback due to involvement of the mesencephalic nucleus of the trigeminal nerve are the proposed pathophysiological mechanisms. Somnolence can also be part of the presentation and is likely due to disruptions of sleep pathways subserved by the reticular activating system. The accurate diagnosis of these cases depends on careful clinical assessment and high index of suspicion for stroke, especially in lieu of preexisting vascular risk factors and lack of an alternative explanation such as toxic-metabolic encephalopathy. PMID:22518226

Common Data Elements for Spinal Cord Injury Clinical Research: A National Institute for Neurological Disorders and Stroke Project

PubMed Central

Biering-Sørensen, Fin; Alai, Sherita; Anderson, Kim; Charlifue, Susan; Chen, Yuying; DeVivo, Michael; Flanders, Adam E.; Jones, Linda; Kleitman, Naomi; Lans, Aria; Noonan, Vanessa K.; Odenkirchen, Joanne; Steeves, John; Tansey, Keith; Widerström-Noga, Eva; Jakeman, Lyn B.

2015-01-01

Objective To develop a comprehensive set of common data elements (CDEs), data definitions, case report forms and guidelines for use in spinal cord injury (SCI) clinical research, as part of the CDE project at the National Institute of Neurological Disorders and Stroke (NINDS) of the USA National Institutes of Health. Setting International Working Groups Methods Nine working groups composed of international experts reviewed existing CDEs and instruments, created new elements when needed, and provided recommendations for SCI clinical research. The project was carried out in collaboration with and cross-referenced to development of the International Spinal Cord Society (ISCoS) International SCI Data Sets. The recommendations were compiled, subjected to internal review, and posted online for external public comment. The final version was reviewed by all working groups and the NINDS CDE team prior to release. Results The NINDS SCI CDEs and supporting documents are publically available on the NINDS CDE website and the ISCoS website. The CDEs span the continuum of SCI care and the full range of domains of the International Classification of Functioning, Disability and Health. Conclusions Widespread use of common data elements can facilitate SCI clinical research and trial design, data sharing, and retrospective analyses. Continued international collaboration will enable consistent data collection and reporting, and will help ensure that the data elements are updated, reviewed and broadcast as additional evidence is obtained. PMID:25665542

Methods and apparatus for vertical coupling from dielectric waveguides

DOEpatents

Yaacobi, Ami; Cordova, Brad Gilbert

2014-06-17

A frequency-chirped nano-antenna provides efficient sub-wavelength vertical emission from a dielectric waveguide. In one example, this nano-antenna includes a set of plasmonic dipoles on the opposite side of a SiYV.sub.4 waveguide from a ground plane. The resulting structure, which is less than half a wavelength long, emits a broadband beam (e.g., >300 nm) that can be coupled into an optical fiber. In some embodiments, a diffractive optical element with unevenly shaped regions of high- and low-index dielectric material collimates the broadband beam for higher coupling efficiency. In some cases, a negative lens element between the nano-antenna and the diffractive optical element accelerates the emitted beam's divergence (and improves coupling efficiency), allowing for more compact packaging. Like the diffractive optical element, the negative lens element includes unevenly shaped regions of high- and low-index dielectric material that can be designed to compensate for aberrations in the beam emitted by the nano-antenna.

Incidence and Risk Factors for Acute Kidney Injury Following Mannitol Infusion in Patients With Acute Stroke

PubMed Central

Lin, Shin-Yi; Tang, Sung-Chun; Tsai, Li-Kai; Yeh, Shin-Joe; Shen, Li-Jiuan; Wu, Fe-Lin Lin; Jeng, Jiann-Shing

2015-01-01

Abstract Mannitol, an osmotic diuretic, is commonly used to treat patients with acute brain edema, but its use also increases the risk of developing acute kidney injury (AKI). In this study, we investigated the incidence and risk factors of mannitol-related AKI in acute stroke patients. A total of 432 patients (ischemic stroke 62.3%) >20 years of age who were admitted to the neurocritical care center in a tertiary hospital and received mannitol treatment were enrolled in this study. Clinical parameters including the scores of National Institutes of Health Stroke Scale (NIHSS) at admission, vascular risk factors, laboratory data, and concurrent nephrotoxic medications were registered. Acute kidney injury was defined as an absolute elevation in the serum creatinine (Scr) level of ≥0.3 mg/dL from the baseline or a ≥50% increase in Scr. The incidence of mannitol-related AKI was 6.5% (95% confidence interval, 4.5%–9.3%) in acute stroke patients, 6.3% in patients with ischemic stroke, and 6.7% in patients with intracerebral hemorrhage. Multivariate analysis revealed that diabetes, lower estimated glomerular filtration rate at baseline, higher initial NIHSS score, and concurrent use of diuretics increased the risk of mannitol-related AKI. When present, the combination of these elements displayed an area under the receiver operating characteristic curve of 0.839 (95% confidence interval, 0.770–0.909). In conclusion, mannitol-related AKI is not uncommon in the treatment of acute stroke patients, especially in those with vulnerable risk factors. PMID:26632702

Incidence and Risk Factors for Acute Kidney Injury Following Mannitol Infusion in Patients With Acute Stroke: A Retrospective Cohort Study.

PubMed

Lin, Shin-Yi; Tang, Sung-Chun; Tsai, Li-Kai; Yeh, Shin-Joe; Shen, Li-Jiuan; Wu, Fe-Lin Lin; Jeng, Jiann-Shing

2015-11-01

Mannitol, an osmotic diuretic, is commonly used to treat patients with acute brain edema, but its use also increases the risk of developing acute kidney injury (AKI). In this study, we investigated the incidence and risk factors of mannitol-related AKI in acute stroke patients.A total of 432 patients (ischemic stroke 62.3%) >20 years of age who were admitted to the neurocritical care center in a tertiary hospital and received mannitol treatment were enrolled in this study. Clinical parameters including the scores of National Institutes of Health Stroke Scale (NIHSS) at admission, vascular risk factors, laboratory data, and concurrent nephrotoxic medications were registered. Acute kidney injury was defined as an absolute elevation in the serum creatinine (Scr) level of ≥0.3 mg/dL from the baseline or a ≥50% increase in Scr.The incidence of mannitol-related AKI was 6.5% (95% confidence interval, 4.5%-9.3%) in acute stroke patients, 6.3% in patients with ischemic stroke, and 6.7% in patients with intracerebral hemorrhage. Multivariate analysis revealed that diabetes, lower estimated glomerular filtration rate at baseline, higher initial NIHSS score, and concurrent use of diuretics increased the risk of mannitol-related AKI. When present, the combination of these elements displayed an area under the receiver operating characteristic curve of 0.839 (95% confidence interval, 0.770-0.909). In conclusion, mannitol-related AKI is not uncommon in the treatment of acute stroke patients, especially in those with vulnerable risk factors.

Contactor/filter improvements

DOEpatents

Stelman, D.

1988-06-30

A contactor/filter arrangement for removing particulate contaminants from a gaseous stream is described. The filter includes a housing having a substantially vertically oriented granular material retention member with upstream and downstream faces, a substantially vertically oriented microporous gas filter element, wherein the retention member and the filter element are spaced apart to provide a zone for the passage of granular material therethrough. A gaseous stream containing particulate contaminants passes through the gas inlet means as well as through the upstream face of the granular material retention member, passing through the retention member, the body of granular material, the microporous gas filter element, exiting out of the gas outlet means. A cover screen isolates the filter element from contact with the moving granular bed. In one embodiment, the granular material is comprised of porous alumina impregnated with CuO, with the cover screen cleaned by the action of the moving granular material as well as by backflow pressure pulses. 6 figs.

Autonomous orbital navigation using Kepler's equation

NASA Technical Reports Server (NTRS)

Boltz, F. W.

1974-01-01

A simple method of determining the six elements of elliptic satellite orbits has been developed for use aboard manned and unmanned spacecraft orbiting the earth, moon, or any planet. The system requires the use of a horizon sensor or other device for determining the local vertical, a precision clock or timing device, and Apollo-type navigation equipment including an inertial measurement unit (IMU), a digital computer, and a coupling data unit. The three elements defining the in-plane motion are obtained from simultaneous measurements of central angle traversed around the planet and elapsed flight time using a linearization of Kepler's equation about a reference orbit. It is shown how Kalman filter theory may also be used to determine the in-plane orbital elements. The three elements defining the orbit orientation are obtained from position angles in celestial coordinates derived from the IMU with the spacecraft vertically oriented after alignment of the IMU to a known inertial coordinate frame.

Physical Therapy Adjuvants to Promote Optimization of Walking Recovery after Stroke

PubMed Central

Bowden, Mark G.; Embry, Aaron E.; Gregory, Chris M.

2011-01-01

Stroke commonly results in substantial and persistent deficits in locomotor function. The majority of scientific inquiries have focused on singular intervention approaches, with recent attention given to task specific therapies. We propose that measurement should indicate the most critical limiting factor(s) to be addressed and that a combination of adjuvant treatments individualized to target accompanying impairment(s) will result in the greatest improvements in locomotor function. We explore training to improve walking performance by addressing a combination of: (1) walking specific motor control; (2) dynamic balance; (3) cardiorespiratory fitness and (4) muscle strength and put forward a theoretical framework to maximize the functional benefits of these strategies as physical adjuvants. The extent to which any of these impairments contribute to locomotor dysfunction is dependent on the individual and will undoubtedly change throughout the rehabilitation intervention. Thus, the ability to identify and measure the relative contributions of these elements will allow for identification of a primary intervention as well as prescription of additional adjuvant approaches. Importantly, we highlight the need for future studies as appropriate dosing of each of these elements is contingent on improving the capacity to measure each element and to titrate the contribution of each to optimal walking performance. PMID:22013549

Imaging cerebral haemorrhage with magnetic induction tomography: numerical modelling.

PubMed

Zolgharni, M; Ledger, P D; Armitage, D W; Holder, D S; Griffiths, H

2009-06-01

Magnetic induction tomography (MIT) is a new electromagnetic imaging modality which has the potential to image changes in the electrical conductivity of the brain due to different pathologies. In this study the feasibility of detecting haemorrhagic cerebral stroke with a 16-channel MIT system operating at 10 MHz was investigated. The finite-element method combined with a realistic, multi-layer, head model comprising 12 different tissues, was used for the simulations in the commercial FE package, Comsol Multiphysics. The eddy-current problem was solved and the MIT signals computed for strokes of different volumes occurring at different locations in the brain. The results revealed that a large, peripheral stroke (volume 49 cm(3)) produced phase changes that would be detectable with our currently achievable instrumentation phase noise level (17 m degrees ) in 70 (27%) of the 256 exciter/sensor channel combinations. However, reconstructed images showed that a lower noise level than this, of 1 m degrees , was necessary to obtain good visualization of the strokes. The simulated MIT measurements were compared with those from an independent transmission-line-matrix model in order to give confidence in the results.

Soil settlement analysis in soft soil by using preloading system and prefabricated vertical draining runway of Kualanamu Airport

NASA Astrophysics Data System (ADS)

Roesyanto; Iskandar, R.; Silalahi, S. A.; Fadliansyah

2018-02-01

The method of soil improvement, using the combination of prefabricated vertical drain (PVD) and preloading, was used to accelerate the process of consolidation and the consolidation settlement in the runway of Kualanamu International Airport, which was constructed on the soft soil sediment like silty clay. In this research, the investigated area was the runway of Kualanamu International Airport zone I which had 11 meter-thickness of soft soil. Geotechnic instruments surveyed was settlement plate. Monitoring was done toward the behavior of landfill such as basic soil settlement. The result were compared with the analysis of finite element method of full scale in Mohr-Coulomb model by verifying the vertical drain of asymmetric unit cell and equivalent plane strain unit cell condition. The results of the research showed that there were an interesting behavior between the data in field observation and finite element of Mohr-Coulomb model. It was also found that the result of soil settlement of finite element method of Mohr-Coulomb model was closed to the result of settlement plate monitoring.

Blanking Method with Aid of Scrap to Reduce Tensile Residual Stress on Sheared Edge

NASA Astrophysics Data System (ADS)

Yasutomi, T.; Yonemura, S.; Yoshida, T.; Mizumura, M.; Hiwatashi, S.

2017-09-01

A simple shearing method to reduce tensile residual stress on a sheared edge is highly desired in the automotive industry because this type of stress deteriorates the fatigue property of automotive parts. In this study, the effect of a coining method with a shearing scrap material on a sheared edge was investigated. The scrap part of a sheared plate has a fracture surface shape similar to that of the product part since these parts are generated by separation of a single plate with crack propagation. Therefore, it is possible to impose plastic strain over the entire fracture surface by using the scrap part as a coining tool. Effectiveness of this method was investigated for high-tensile-strength steel. Using this method, the tensile residual stress on the sheared surface was significantly reduced and work hardening was slightly increased. The effects of shearing clearance and coining stroke were also investigated. Tensile residual stress decreased as the coining stroke increased; however, it saturated at a certain stroke. The stroke at which tensile residual stress saturated was relatively small at a large clearance. In particular, the amount of plastic deformation on fracture surface increased when coining stroke became large. These tendencies could be explained by the conditions of contact, which were investigated using finite element analysis.

Efficient Computation of Atmospheric Flows with Tempest: Validation of Next-Generation Climate and Weather Prediction Algorithms at Non-Hydrostatic Scales

NASA Astrophysics Data System (ADS)

Guerra, Jorge; Ullrich, Paul

2016-04-01

Tempest is a next-generation global climate and weather simulation platform designed to allow experimentation with numerical methods for a wide range of spatial resolutions. The atmospheric fluid equations are discretized by continuous / discontinuous finite elements in the horizontal and by a staggered nodal finite element method (SNFEM) in the vertical, coupled with implicit/explicit time integration. At horizontal resolutions below 10km, many important questions remain on optimal techniques for solving the fluid equations. We present results from a suite of idealized test cases to validate the performance of the SNFEM applied in the vertical with an emphasis on flow features and dynamic behavior. Internal gravity wave, mountain wave, convective bubble, and Cartesian baroclinic instability tests will be shown at various vertical orders of accuracy and compared with known results.

Using occlusal wear information and finite element analysis to investigate stress distributions in human molars

PubMed Central

Benazzi, Stefano; Kullmer, Ottmar; Grosse, Ian R; Weber, Gerhard W

2011-01-01

Simulations based on finite element analysis (FEA) have attracted increasing interest in dentistry and dental anthropology for evaluating the stress and strain distribution in teeth under occlusal loading conditions. Nonetheless, FEA is usually applied without considering changes in contacts between antagonistic teeth during the occlusal power stroke. In this contribution we show how occlusal information can be used to investigate the stress distribution with 3D FEA in lower first molars (M1). The antagonistic crowns M1 and P2–M1 of two dried modern human skulls were scanned by μCT in maximum intercuspation (centric occlusion) contact. A virtual analysis of the occlusal power stroke between M1 and P2–M1 was carried out in the Occlusal Fingerprint Analyser (OFA) software, and the occlusal trajectory path was recorded, while contact areas per time-step were visualized and quantified. Stress distribution of the M1 in selected occlusal stages were analyzed in strand7, considering occlusal information taken from OFA results for individual loading direction and loading area. Our FEA results show that the stress pattern changes considerably during the power stroke, suggesting that wear facets have a crucial influence on the distribution of stress on the whole tooth. Grooves and fissures on the occlusal surface are seen as critical locations, as tensile stresses are concentrated at these features. Properly accounting for the power stroke kinematics of occluding teeth results in quite different results (less tensile stresses in the crown) than usual loading scenarios based on parallel forces to the long axis of the tooth. This leads to the conclusion that functional studies considering kinematics of teeth are important to understand biomechanics and interpret morphological adaptation of teeth. PMID:21615398

Finite-element analysis and modal testing of a rotating wind turbine

NASA Astrophysics Data System (ADS)

Carne, T. G.; Lobitz, D. W.; Nord, A. R.; Watson, R. A.

1982-10-01

A finite element procedure, which includes geometric stiffening, and centrifugal and Coriolis terms resulting from the use of a rotating coordinate system, was developed to compute the mode shapes and frequencies of rotating structures. Special applications of this capability was made to Darrieus, vertical axis wind turbines. In a parallel development effort, a technique for the modal testing of a rotating vertical axis wind turbine is established to measure modal parameters directly. Results from the predictive and experimental techniques for the modal frequencies and mode shapes are compared over a wide range of rotational speeds.

Finite element analysis and modal testing of a rotating wind turbine

NASA Astrophysics Data System (ADS)

Carne, T. G.; Lobitz, D. W.; Nord, A. R.; Watson, R. A.

A finite element procedure, which includes geometric stiffening, and centrifugal and Coriolis terms resulting from the use of a rotating coordinate system, has been developed to compute the mode shapes and frequencies of rotating structures. Special application of this capability has been made to Darrieus, vertical axis wind turbines. In a parallel development effort, a technique for the modal testing of a rotating vertical axis wind turbine has been established to measure modal parameters directly. Results from the predictive and experimental techniques for the modal frequencies and mode shapes are compared over a wide range of rotational speeds.

Multisensory Stimulation to Improve Low- and Higher-Level Sensory Deficits after Stroke: A Systematic Review.

PubMed

Tinga, Angelica Maria; Visser-Meily, Johanna Maria Augusta; van der Smagt, Maarten Jeroen; Van der Stigchel, Stefan; van Ee, Raymond; Nijboer, Tanja Cornelia Wilhelmina

2016-03-01

The aim of this systematic review was to integrate and assess evidence for the effectiveness of multisensory stimulation (i.e., stimulating at least two of the following sensory systems: visual, auditory, and somatosensory) as a possible rehabilitation method after stroke. Evidence was considered with a focus on low-level, perceptual (visual, auditory and somatosensory deficits), as well as higher-level, cognitive, sensory deficits. We referred to the electronic databases Scopus and PubMed to search for articles that were published before May 2015. Studies were included which evaluated the effects of multisensory stimulation on patients with low- or higher-level sensory deficits caused by stroke. Twenty-one studies were included in this review and the quality of these studies was assessed (based on eight elements: randomization, inclusion of control patient group, blinding of participants, blinding of researchers, follow-up, group size, reporting effect sizes, and reporting time post-stroke). Twenty of the twenty-one included studies demonstrate beneficial effects on low- and/or higher-level sensory deficits after stroke. Notwithstanding these beneficial effects, the quality of the studies is insufficient for valid conclusion that multisensory stimulation can be successfully applied as an effective intervention. A valuable and necessary next step would be to set up well-designed randomized controlled trials to examine the effectiveness of multisensory stimulation as an intervention for low- and/or higher-level sensory deficits after stroke. Finally, we consider the potential mechanisms of multisensory stimulation for rehabilitation to guide this future research.

Vertical viewing angle enhancement for the 360  degree integral-floating display using an anamorphic optic system.

PubMed

Erdenebat, Munkh-Uchral; Kwon, Ki-Chul; Yoo, Kwan-Hee; Baasantseren, Ganbat; Park, Jae-Hyeung; Kim, Eun-Soo; Kim, Nam

2014-04-15

We propose a 360 degree integral-floating display with an enhanced vertical viewing angle. The system projects two-dimensional elemental image arrays via a high-speed digital micromirror device projector and reconstructs them into 3D perspectives with a lens array. Double floating lenses relate initial 3D perspectives to the center of a vertically curved convex mirror. The anamorphic optic system tailors the initial 3D perspectives horizontally and vertically disperse light rays more widely. By the proposed method, the entire 3D image provides both monocular and binocular depth cues, a full-parallax demonstration with high-angular ray density and an enhanced vertical viewing angle.

Three-dimensional flow structures and evolution of the leading-edge vortices on a flapping wing.

PubMed

Lu, Yuan; Shen, Gong Xin

2008-04-01

Following the identification and confirmation of the substructures of the leading-edge vortex (LEV) system on flapping wings, it is apparent that the actual LEV structures could be more complex than had been estimated in previous investigations. In this experimental study, we reveal for the first time the detailed three-dimensional (3-D) flow structures and evolution of the LEVs on a flapping wing in the hovering condition at high Reynolds number (Re=1624). This was accomplished by utilizing an electromechanical model dragonfly wing flapping in a water tank (mid-stroke angle of attack=60 degrees) and applying phase-lock based multi-slice digital stereoscopic particle image velocimetry (DSPIV) to measure the target flow fields at three typical stroke phases: at 0.125 T (T=stroke period), when the wing was accelerating; at 0.25 T, when the wing had maximum speed; and at 0.375 T, when the wing was decelerating. The result shows that the LEV system is a collection of four vortical elements: one primary vortex and three minor vortices, instead of a single conical or tube-like vortex as reported or hypothesized in previous studies. These vortical elements are highly time-dependent in structure and show distinct ;stay properties' at different spanwise sections. The spanwise flows are also time-dependent, not only in the velocity magnitude but also in direction.

Inventory of available data elements for the San Bernardino, California region

NASA Technical Reports Server (NTRS)

Christenson, J.; Michel, R.

1981-01-01

Elements of data sets that are available to be integrated for the San Bernardino vertical data integration project are given. Each of the data sets has specified for it the ownership, validity, accuracy and technical requirements for integration.

[The use of a robot-assisted Gait Trainer GT1 in patients in the acute period of cerebral stroke: a pilot study].

PubMed

Skvortsova, V I; Ivanova, G E; Kovrazhkina, E A; Rumiantseva, N A; Staritsyn, A N; Suvorov, A Iu; Sogomonian, E K

2008-01-01

An aim of the study was to evaluate efficacy of using Gait Trainer GT1, a robot-assisted gait trainer with a system of body-weight support, for the rehabilitation of gait in patients in the acute period of cerebral stroke. A main group included 30 patients in the acute period of ischemic and hemorrhage stroke and a control group--20 age- and sex matched patients. Patients of both groups had daily kinesitherapy sessions with a rehabilitator. Patients of the main group had additional sessions on the Gait Trainer GT1 from the moment of functional readiness to adequate orthostatic probe. Efficacy of rehabilitation was assessed in the four following phases: the first verticalization of patient in the standing position, adaptation of patient to the standing position, walking with assistance, independent walking. Muscular power (scores) in all muscles of low extremities, muscle tonus (the Ashfort scale), amplitude of tendinous reflexes on the reflexes scale, sensory disturbances and discoordination syndromes (specially elaborated scales), pathological positions in the axial muscular system and extremities, functional status (a steadiness scale, the Berg balance scale, the Barthel scale, 5 m test) were assessed in each phase. Stabilometry was conducted for objective evaluation of vertical balance function. The duration of sessions on GT1 and a number of exercises were depended on the patient's tolerability to physical activity. Percentage of relief was determined by the ability of a patient to balance in the standing position. Each patient had 8-10 sessions. A significant improvement of the functional status: ability to balance in standing position, walking, increase of self-care skills were observed in both groups. No significant differences in the level of functional improvements were found compared to the control group. However some peculiarities of the rehabilitation of primary neurologic deficit were observed during CT1-trainings: the normalization of muscle tonus both in spastic and hypotonic muscles, predominate rehabilitation of flexor muscular system (p = 0.005), significant improvement of deep and surface sensitivity (p < 0.005). The stabilometric data revealed the normalization of strategy of vertical posture support--from hip to ankle (p = 0.001), proprioceptive control of balance by the Romberg coefficient (p = 0.005). Robot-assisted gait trainers are commonly used in trainings of step patterns in highly disabled patients who are not able to walk without assistance. These peculiarities of the rehabilitation of primary neurologic deficit during the GT-trainings allowed to use a differential approach to a candidate selection for the sessions.

Wing and body kinematics of forward flight in drone-flies.

PubMed

Meng, Xue Guang; Sun, Mao

2016-08-15

Here, we present a detailed analysis of the wing and body kinematics in drone-flies in free flight over a range of speeds from hovering to about 8.5 m s(-1). The kinematics was measured by high-speed video techniques. As the speed increased, the body angle decreased and the stroke plane angle increased; the wingbeat frequency changed little; the stroke amplitude first decreased and then increased; the ratio of the downstroke duration to the upstroke duration increased; the mean positional angle increased at lower speeds but changed little at speeds above 3 m s(-1). At a speed above about 1.5 m s(-1), wing rotation at supination was delayed and that at pronation was advanced, and consequently the wing rotations were mostly performed in the upstroke. In the downstroke, the relative velocity of the wing increased and the effective angle of attack decreased with speed; in the upstroke, they both decreased with speed at lower speeds, and at higher speeds, the relative velocity became larger but the effective angle of attack became very small. As speed increased, the increasing inclination of the stroke plane ensured that the effective angle of attack in the upstroke would not become negative, and that the wing was in suitable orientations for vertical-force and thrust production.

New Technical Solution for Vertical Shaft Equipping Using Steel Headframe of Multifunction Purpose

NASA Astrophysics Data System (ADS)

Kassikhina, Elena; Pershin, Vladimir; Glazkov, Yurij

2017-11-01

The article reviews a novel approach to the design of steel angle headframe for vertical shafts of coal and ore mines on the basis of rational design solutions. Practice of construction of coal and ore mines provides application of various designs for steel angle headframes which are divided into separate large assembly blocks and constructive elements during assembling operations. Design of these blocks and elements, their weight and dimensions effect the chose of the method of assembling on which economic and technological indicators, as well as duration of down-time, depend on during performance of construction operations in shaft. The technical solution on equipment provision for mine vertical shaft using headframe of multifunctional purpose will allow changing the management construction of vertical shaft. The constructive design of the headgear allows application of the effective method of assembly and thus to provide improvement of the technical and economic indexes, and high calendar time rate of the shaft construction due to reduction of duration of works on equipment provision for the shaft and to refurbishment of the shaft in order to carry out horizontal mining.

Five-minute Oscillation Power within Magnetic Elements in the Solar Atmosphere

NASA Astrophysics Data System (ADS)

Jain, Rekha; Gascoyne, Andrew; Hindman, Bradley W.; Greer, Benjamin

2014-12-01

It has long been known that magnetic plage and sunspots are regions in which the power of acoustic waves is reduced within the photospheric layers. Recent observations now suggest that this suppression of power extends into the low chromosphere and is also present in small magnetic elements far from active regions. In this paper we investigate the observed power suppression in plage and magnetic elements, by modeling each as a collection of vertically aligned magnetic fibrils and presuming that the velocity within each fibril is the response to buffeting by incident p modes in the surrounding field-free atmosphere. We restrict our attention to modeling observations made near the solar disk center, where the line-of-sight velocity is nearly vertical and hence, only the longitudinal component of the motion within the fibril contributes. Therefore, we only consider the excitation of axisymmetric sausage waves and ignore kink oscillations as their motions are primarily horizontal. We compare the vertical motion within the fibril with the vertical motion of the incident p mode by constructing the ratio of their powers. In agreement with observational measurements we find that the total power is suppressed within strong magnetic elements for frequencies below the acoustic cut-off frequency. However, further physical effects need to be examined for understanding the observed power ratios for stronger magnetic field strengths and higher frequencies. We also find that the magnitude of the power deficit increases with the height above the photosphere at which the measurement is made. Furthermore, we argue that the area of the solar disk over which the power suppression extends increases as a function of height.

Evaluation of stress distribution of implant-retained mandibular overdenture with different vertical restorative spaces: A finite element analysis

PubMed Central

Ebadian, Behnaz; Farzin, Mahmoud; Talebi, Saeid; Khodaeian, Niloufar

2012-01-01

Background: Available restorative space and bar height is an important factor in stress distribution of implant-supported overdentures. The purpose of this study was to evaluate the effect of different vertical restorative spaces and different bar heights on the stress distribution around implants by 3D finite element analysis. Materials and Methods: 3D finite element models were developed from mandibular overdentures with two implants in the interforaminal region. In these models, four different bar heights from gingival crest (0.5, 1, 1.5, 2 mm) with 15 mm occlusal plane height and three different occlusal plane heights from gingival crest (9, 12, 15 mm) with 2 mm bar height were analyzed. A vertical unilateral and a bilateral load of 150 N were applied to the central occlusal fossa of the first molar and the stress of bone around implant was analyzed by finite element analysis. Results: By increasing vertical restorative space, the maximum stress values around implants were found to be decreased in unilateral loading models but slightly increased in bilateral loading cases. By increasing bar height from gingival crest, the maximum stress values around implants were found to be increased in unilateral loading models but slightly decreased in bilateral loading cases. In unilateral loading models, maximum stress was found in a model with 9 mm occlusal plane height and 1.5 mm bar height (6.254 MPa), but in bilateral loading cases, maximum stress was found in a model with 15 mm occlusal plane height and 0.5 mm bar height (3.482 MPa). Conclusion: The reduction of bar height and increase in the thickness of acrylic resin base in implant-supported overdentures are biomechanically favorable and may result in less stress in periimplant bone. PMID:23559952

Gait post-stroke: Pathophysiology and rehabilitation strategies.

PubMed

Beyaert, C; Vasa, R; Frykberg, G E

2015-11-01

We reviewed neural control and biomechanical description of gait in both non-disabled and post-stroke subjects. In addition, we reviewed most of the gait rehabilitation strategies currently in use or in development and observed their principles in relation to recent pathophysiology of post-stroke gait. In both non-disabled and post-stroke subjects, motor control is organized on a task-oriented basis using a common set of a few muscle modules to simultaneously achieve body support, balance control, and forward progression during gait. Hemiparesis following stroke is due to disruption of descending neural pathways, usually with no direct lesion of the brainstem and cerebellar structures involved in motor automatic processes. Post-stroke, improvements of motor activities including standing and locomotion are variable but are typically characterized by a common postural behaviour which involves the unaffected side more for body support and balance control, likely in response to initial muscle weakness of the affected side. Various rehabilitation strategies are regularly used or in development, targeting muscle activity, postural and gait tasks, using more or less high-technology equipment. Reduced walking speed often improves with time and with various rehabilitation strategies, but asymmetric postural behaviour during standing and walking is often reinforced, maintained, or only transitorily decreased. This asymmetric compensatory postural behaviour appears to be robust, driven by support and balance tasks maintaining the predominant use of the unaffected side over the initially impaired affected side. Based on these elements, stroke rehabilitation including affected muscle strengthening and often stretching would first need to correct the postural asymmetric pattern by exploiting postural automatic processes in various particular motor tasks secondarily beneficial to gait. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Dynamic characteristics and simplified numerical methods of an all-vertical-piled wharf in offshore deep water

NASA Astrophysics Data System (ADS)

Zhang, Hua-qing; Sun, Xi-ping; Wang, Yuan-zhan; Yin, Ji-long; Wang, Chao-yang

2015-10-01

There has been a growing trend in the development of offshore deep-water ports in China. For such deep sea projects, all-vertical-piled wharves are suitable structures and generally located in open waters, greatly affected by wave action. Currently, no systematic studies or simplified numerical methods are available for deriving the dynamic characteristics and dynamic responses of all-vertical-piled wharves under wave cyclic loads. In this article, we compare the dynamic characteristics of an all-vertical-piled wharf with those of a traditional inshore high-piled wharf through numerical analysis; our research reveals that the vibration period of an all-vertical-piled wharf under cyclic loading is longer than that of an inshore high-piled wharf and is much closer to the period of the loading wave. Therefore, dynamic calculation and analysis should be conducted when designing and calculating the characteristics of an all-vertical-piled wharf. We establish a dynamic finite element model to examine the dynamic response of an all-vertical-piled wharf under wave cyclic loads and compare the results with those under wave equivalent static load; the comparison indicates that dynamic amplification of the structure is evident when the wave dynamic load effect is taken into account. Furthermore, a simplified dynamic numerical method for calculating the dynamic response of an all-vertical-piled wharf is established based on the P-Y curve. Compared with finite element analysis, the simplified method is more convenient to use and applicable to large structural deformation while considering the soil non-linearity. We confirmed that the simplified method has acceptable accuracy and can be used in engineering applications.

The NASA Lightning Nitrogen Oxides Model (LNOM): Application to Air Quality Modeling

NASA Technical Reports Server (NTRS)

Koshak, William; Peterson, Harold; Khan, Maudood; Biazar, Arastoo; Wang, Lihua

2011-01-01

Recent improvements to the NASA Marshall Space Flight Center Lightning Nitrogen Oxides Model (LNOM) and its application to the Community Multiscale Air Quality (CMAQ) modeling system are discussed. The LNOM analyzes Lightning Mapping Array (LMA) and National Lightning Detection Network(TradeMark)(NLDN) data to estimate the raw (i.e., unmixed and otherwise environmentally unmodified) vertical profile of lightning NO(x) (= NO + NO2). The latest LNOM estimates of lightning channel length distributions, lightning 1-m segment altitude distributions, and the vertical profile of lightning NO(x) are presented. The primary improvement to the LNOM is the inclusion of non-return stroke lightning NOx production due to: (1) hot core stepped and dart leaders, (2) stepped leader corona sheath, K-changes, continuing currents, and M-components. The impact of including LNOM-estimates of lightning NO(x) for an August 2006 run of CMAQ is discussed.

Vertical velocity structure and geometry of clear air convective elements

NASA Technical Reports Server (NTRS)

Rowland, J. R.; Arnold, A.

1975-01-01

The paper discusses observations of individual convective elements with a high-power narrow-beam scanning radar, an FM-CW radar, and an acoustic sounder, including the determination of the vertical air velocity patterns of convective structures with the FM-CW radar and acoustic sounder. Data are presented which link the observed velocity structure and geometrical patterns to previously proposed models of boundary layer convection. It is shown that the high-power radar provides a clear three-dimensional picture of convective cells and fields over a large area with a resolution of 150 m, where the convective cells are roughly spherical. Analysis of time-height records of the FM-CW radar and acoustic sounder confirms the downdraft-entrainment mechanism of the convective cell. The Doppler return of the acoustic sounder and the insect-trail slopes on FM-CW radar records are independent but redundant methods for obtaining the vertical velocity patterns of convective structures.

Tempest: Mesoscale test case suite results and the effect of order-of-accuracy on pressure gradient force errors

NASA Astrophysics Data System (ADS)

Guerra, J. E.; Ullrich, P. A.

2014-12-01

Tempest is a new non-hydrostatic atmospheric modeling framework that allows for investigation and intercomparison of high-order numerical methods. It is composed of a dynamical core based on a finite-element formulation of arbitrary order operating on cubed-sphere and Cartesian meshes with topography. The underlying technology is briefly discussed, including a novel Hybrid Finite Element Method (HFEM) vertical coordinate coupled with high-order Implicit/Explicit (IMEX) time integration to control vertically propagating sound waves. Here, we show results from a suite of Mesoscale testing cases from the literature that demonstrate the accuracy, performance, and properties of Tempest on regular Cartesian meshes. The test cases include wave propagation behavior, Kelvin-Helmholtz instabilities, and flow interaction with topography. Comparisons are made to existing results highlighting improvements made in resolving atmospheric dynamics in the vertical direction where many existing methods are deficient.

The effect of aquatic therapy on postural balance and muscle strength in stroke survivors--a randomized controlled pilot trial.

PubMed

Noh, Dong Koog; Lim, Jae-Young; Shin, Hyung-Ik; Paik, Nam-Jong

2008-01-01

To evaluate the effect of an aquatic therapy programme designed to increase balance in stroke survivors. A randomized, controlled pilot trial. Rehabilitation department of a university hospital. Ambulatory chronic stroke patients (n = 25):13 in an aquatic therapy group and 12 in a conventional therapy group. The aquatic therapy group participated in a programme consisting of Ai Chi and Halliwick methods, which focused on balance and weight-bearing exercises. The conventional therapy group performed gym exercises. In both groups, the interventions occurred for 1 hour, three times per week, for eight weeks. The primary outcome measures were Berg Balance Scale score and weight-bearing ability, as measured by vertical ground reaction force during four standing tasks (rising from a chair and weight-shifting forward, backward and laterally). Secondary measures were muscle strength and gait. Compared with the conventional therapy group, the aquatic therapy group attained significant improvements in Berg Balance Scale scores, forward and backward weight-bearing abilities of the affected limbs, and knee flexor strength (P < 0.05), with effect sizes of 1.03, 1.14, 0.72 and 1.13 standard deviation units and powers of 75, 81, 70 and 26%, respectively. There were no significant changes in the other measures between the two groups. Postural balance and knee flexor strength were improved after aquatic therapy based on the Halliwick and Ai Chi methods in stroke survivors. Because of limited power and a small population base, further studies with larger sample sizes are required.

Control for small-speed lateral flight in a model insect.

PubMed

Zhang, Yan Lai; Sun, Mao

2011-09-01

Controls required for small-speed lateral flight of a model insect were studied using techniques based on the linear theories of stability and control (the stability and control derivatives were computed by the method of computational fluid dynamics). The main results are as follows. (1) Two steady-state lateral motions can exist: one is a horizontal side translation with the body rolling to the same side of the translation by a small angle, and the other is a constant-rate yaw rotation (rotation about the vertical axis). (2) The side translation requires an anti-symmetrical change in the stroke amplitudes of the contralateral wings, and/or an anti-symmetrical change in the angles of attack of the contralateral wings, with the down- and upstroke angles of attack of a wing having equal change. The constant-rate yaw rotation requires an anti-symmetrical change in the angles of attack of the contralateral wings, with the down- and upstroke angles of attack of a wing having differential change. (3) For the control of the horizontal side translation, control input required for the steady-state motion has an opposite sign to that needed for initiating the motion. For example, to have a steady-state left side-translation, the insect needs to increase the stroke amplitude of the left wing and decrease that of the right wing to maintain the steady-state flight, but it needs an opposite change in stroke amplitude (decreasing the stroke amplitude of the left wing and increasing that of the right wing) to enter the flight.

Rack for storing spent nuclear fuel elements

DOEpatents

Rubinstein, Herbert J.; Clark, Philip M.; Gilcrest, James D.

1978-06-20

A rack for storing spent nuclear fuel elements in which a plurality of aligned rows of upright enclosures of generally square cross-sectional areas contain vertically disposed fuel elements. The enclosures are fixed at the lower ends thereof to a base. Pockets are formed between confronting walls of adjacent enclosures for receiving high absorption neutron absorbers, such as Boral, cadmium, borated stainless steel and the like for the closer spacing of spent fuel elements.

Operational alternatives for LANDSAT in California

NASA Technical Reports Server (NTRS)

Wilson, P.; Gialdini, M. J.

1981-01-01

Data integration is defined and examined as the means of promoting data sharing among the various governmental and private geobased information systems in California. Elements of vertical integration considered included technical factors (such as resolution and classification) and institutional factors (such as organizational control, and legal and political barriers). Attempts are made to fit the theoretical elements of vertical integration into a meaningful structure for looking at the problem from a statewide focus. Both manual (mapped) and machine readable data systems are included. Special attention is given to LANDSAT imagery because of its strong potential for integrated use and its primary in the California Integrated Remote Sensing System program.

The effects of tunnel horizontal distance on the vertical deformations of an adjacent building

NASA Astrophysics Data System (ADS)

Balkaya, Müge

2015-12-01

Due to the rapid development of urbanization and the need for effective transportation, it became a common application to construct subway tunnels in modern cities. However, these construction activities may lead to undesirable deformations on the adjacent buildings. In this study, the effect of tunnel horizontal distance on the deformations of an adjacent building is investigated using 2D finite element analysis. The results of the finite element analysis showed that, although high settlement values were not observed for the cases investigated in this study, the vertical deformations of the building decreased as the tunnel moved away from the building.

Vertical distribution of major, minor and trace elements in sediments from mud volcanoes of the Gulf of Cadiz: evidence of Cd, As and Ba fronts in upper layers

NASA Astrophysics Data System (ADS)

Carvalho, Lina; Monteiro, Rui; Figueira, Paula; Mieiro, Cláudia; Almeida, Joana; Pereira, Eduarda; Magalhães, Vítor; Pinheiro, Luís; Vale, Carlos

2018-01-01

Mud volcanoes are feature of the coastal margins where anaerobic oxidation of methane triggers geochemical signals. Elemental composition, percentage of fine particles and loss on ignition were determined in sediment layers of eleven gravity cores retrieved from four mud volcanoes (Sagres, Bonjardim, Soloviev and Porto) and three undefined structures located on the deep Portuguese margin of the Gulf of Cadiz. Calcium was positively correlated to Sr and inversely to Al as well as to most of the trace elements. Vertical profiles of Ba, Cd and As concentrations, and their ratios to Al, in Porto and Soloviev showed pronounced enhancements in the top 50-cm depth. Sub-surface enhancements were less pronounced in other mud volcanoes and were absent in sediments from the structures. These profiles were interpreted as diagenetic enrichments related to the anaerobic oxidation of methane originated from upward methane-rich fluxes. The observed barium fronts were most likely caused by the presence of barite which precipitated at the sulphate-methane transition zone. Cd and As enrichments have probably resulted from successive dissolution/precipitation of sulphides in response to vertical shifts of redox boundaries.

Simulations of the myosin II motor reveal a nucleotide-state sensing element that controls the recovery stroke.

PubMed

Koppole, Sampath; Smith, Jeremy C; Fischer, Stefan

2006-08-18

During the recovery stroke, the myosin motor is primed for the next power stroke by a 60 degree rotation of its lever arm. This reversible motion is coupled to the activation of the ATPase function of myosin through conformational changes along the relay helix, which runs from the Switch-2 loop near the ATP to the converter domain carrying the lever arm. Via a hydrogen bond between the side-chain of Asn475 on the relay helix and the Gly457/Ser456 peptide group on the Switch-2, the rotation of the converter domain is coupled to the formation of a hydrogen bond between Gly457 and gamma-phosphate that is essential for ATP hydrolysis. Here, molecular dynamics simulations of Dictyostelium discoideum myosin II in the two end conformations of the recovery stroke with different nucleotide states (ATP, ADP x Pi, ADP) reveal that the side-chain of Asn475 breaks away from Switch-2 upon ATP hydrolysis to make a hydrogen bond with Tyr573. This sensing of the nucleotide state is achieved by a small displacement of the cleaved gamma-phosphate towards Gly457 which in turn pushes Asn475 away. The sensing plays a dual role by (i) preventing the wasteful reversal of the recovery stroke while the nucleotide is in the ADP x Pi state, and (ii) decoupling the relay helix from Switch-2, thus allowing the power stroke to start upon initial binding to actin while Gly457 of Switch-2 keeps interacting with the Pi (known to be released only later after tight actin binding). A catalytically important salt bridge between Arg238 (on Switch-1) and Glu459 (on Switch-2), which covers the hydrolysis site, is seen to form rapidly when ATP is added to the pre-recovery stroke conformer and remains stable after the recovery stroke, indicating that it has a role in shaping the ATP binding site by induced fit.

Exerciser for rehabilitation of the Arm (ERA): Development and unique features of a 3D end-effector robot.

PubMed

Milot, Marie-Helene; Hamel, Mathieu; Provost, Philippe-Olivier; Bernier-Ouellet, Julien; Dupuis, Maxime; Letourneau, Dominic; Briere, Simon; Michaud, Francois

2016-08-01

Stroke is one of the leading causes of disability worldwide. Consequently, many stroke survivors exhibit difficulties undergoing voluntary movement in their affected upper limb, compromising their functional performance and level of independence. To minimize the negative impact of stroke disabilities, exercises are recognized as a key element in post-stroke rehabilitation. In order to provide the practice of exercises in a uniform and controlled manner as well as increasing the efficiency of therapists' interventions, robotic training has been found, and continues to prove itself, as an innovative intervention for post-stroke rehabilitation. However, the complexity as well as the limited degrees of freedom and workspace of currently commercially available robots can limit their use in clinical settings. Up to now, user-friendly robots covering a sufficiently large workspace for training of the upper limb in its full range of motion are lacking. This paper presents the design and implementation of ERA, an upper-limb 3-DOF force-controlled exerciser robot, which presents a workspace covering the entire range of motion of the upper limb. The ERA robot provides 3D reaching movements in a haptic virtual environment. A description of the hardware and software components of the ERA robot is also presented along with a demonstration of its capabilities in one of the three operational modes that were developed.

Restoring mobility after stroke: first kinematic results from a pilot study with a hybrid drop foot stimulator.

PubMed

Yao, D; Jakubowitz, E; Tecante, K; Lahner, M; Ettinger, S; Claassen, L; Plaass, C; Stukenborg-Colsman, C; Daniilidis, K

2016-12-01

The objective was to obtain first insights into the kinematic and kinetic walking patterns resulting from an implanted functional electrical stimulation system in subjects with a drop foot caused by stroke. Four subjects who experienced a stroke were chosen due to a comparatively long/short time after surgery and young/old at the stroke event were examined retrospectively with gait analysis. Kinematics and kinetics of normal walking were assessed in comparison with and without activated drop foot stimulation. In general, an improvement regarding spatiotemporal parameters as a result of the stimulation could be observed. Walking speed was increased by 45 % and stride length by 22 % after a mean usage of 7 (2-14) months, whereas both younger subjects improved significantly more. Dorsiflexion increased in all subjects on average from 1.3° to 11.6° during initial contact as well as from 11.3° to 17.0° during mid-swing and therefore implies an advantage of around 5.5 inch foot clearance. Pathologic elements like knee hyperextension during loading response and mid-stance, leg circumduction during swing or the increased hip flexion of the contralateral leg during mid-stance could be in general adjusted with stimulation. An implantable functional electrical stimulation system seems to be a promising treatment of drop feet following strokes. Further clinical investigations are necessary to confirm these first insights.

Some properties of the two-body effective interaction in the /sup 208/Pb region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Groleau, R.

The (/sup 3/He,d) and (/sup 4/He,t) single proton transfer reactions on /sup 208/Pb and /sup 209/Bi were studied using 30 and 40 MeV He beams from the Princeton Cyclotron Laboratory. The outgoing d and t were detected by a position sensitive proportional counter in the focal plane of a Q-3D spectrometer. The resolution varied between 10 and 14 keV (FWHM). Using the ratio of the cross-sections for the (/sup 3/He,d) and (/sup 4/He,t) reactions to determine the magnitude of the angular momentum transfers, the spectroscopic factors for the reaction on /sup 209/Bi have been measured relative to the transitions tomore » the single particle states in these reactions on /sup 208/Pb. Sum rules as developed by Bansal and French are used to study the configurations vertical bar h/sub 9/2 x h/sub 9/2/>, vertical bar h/sub 9/2/ x f/sub 7/2/>, vertical bar h/sub 9/2 x i/sub 13/2/>, vertical bar h/sub 9/2/ x f/sub 5/2/>and part of vertical bar h/sub 9/2/ x p/sub 3/2/> and vertical bar h/sub 9/2/ x p/sub 1/2>. Using the linear energy weighted sum rule, the diagonal matrix elements of the effective interaction between valence protons around the /sup 208/Pb core are deduced. The matrix elements obtained from a simple empirical interaction V/sub I//sup T=1/ of a pure Wigner type are compared to the extracted matrix elements. The interaction is characterized by an attractive short-range (0.82j and a repulsive long-range (8.2fm) potential: V/sub I//sup T = 1/ (MeV =-/96 e/sup - (r/0.82) /sup 2// + 0.51 e/sup -(r/8.2)/sup 2/. The core polarization is studied using the experimental static electric quadrupole and magnetic dipole moments of the nuclei in the /sup 208/Pb region. In general, the magnetic moments of multiple valence nucleon nuclei are well predicted by simple rules of Racah algebra. The three and four valence proton spectra (/sup 211/At and /sup 212/Rn) calculated with the experimental two particle matrix elements agree well with the experimental spectra.« less

Passive mechanism of pitch recoil in flapping insect wings.

PubMed

Ishihara, D; Horie, T

2016-12-20

The high torsional flexibility of insect wings allows for elastic recoil after the rotation of the wing during stroke reversal. However, the underlying mechanism of this recoil remains unclear because of the dynamic process of transitioning from the wing rotation during stroke reversal to the maintenance of a high angle of attack during the middle of each half-stroke, when the inertial, elastic, and aerodynamic effects all have a significant impact. Therefore, the interaction between the flapping wing and the surrounding air was directly simulated by simultaneously solving the incompressible Navier-Stokes equations, the equation of motion for an elastic body, and the fluid-structure interface conditions using the three-dimensional finite element method. This direct numerical simulation controlling the aerodynamic effect revealed that the recoil is the residual of the free pitch vibration induced by the flapping acceleration during stroke reversal in the transient response very close to critical damping due to the dynamic pressure resistance of the surrounding air. This understanding will enable the control of the leading-edge vortex and lift generation, the reduction of the work performed by flapping wings, and the interpretation of the underlying necessity for the kinematic characteristics of the flapping motion.

Barriers and Facilitators to Implementing Primary Stroke Center Policy in the United States: Results From 4 Case Study States

PubMed Central

Slade, Catherine P.; Brewer, Gene A.; Gase, Lauren N.

2011-01-01

Objectives. We identified barriers and facilitators to the state-level implementation of primary stroke center (PSC) policies, which encourage the certification or designation of specialized stroke treatment facilities and may address concerns such as transportation bypass, telemedicine, and treatment protocols. Methods. We studied the experiences of 4 states (Florida, Massachusetts, New Mexico, and New York) selected from the 18 states that had enacted PSC policies or were actively considering doing so. We conducted semistructured interviews during fieldwork in each case study state. Results. Our results showed that system fragmentation, gaps in human and financial resources, and complexity at the interorganizational and operational levels are common barriers and that policy champions, stakeholder support and communication, and operational adaptation are essential facilitators in the adoption and implementation of PSC policies. Conclusions. The identification of barriers and facilitators reveals the contextual elements that can help or hinder policy implementation and may be useful in informing policy formulation and implementation in other jurisdictions. Proactively identifying jurisdictional challenges and opportunities may help facilitate the policy process for PSC designation and allow jurisdictions to develop more effective stroke systems of care. PMID:21233430

Design of a Long-Stroke Noncontact Electromagnetic Actuator for Active Vibration Isolation

NASA Technical Reports Server (NTRS)

Banerjee, Bibhuti; Allaire, Paul E.

1996-01-01

A long-stroke moving coil Lorentz Actuator was designed for use in a microgravity vibration isolation experiment. The final design had a stroke of 5.08 cm (2 in) and enough force capability to isolate a mass of the order of 22.7-45.4 kg. A simple dynamic magnetic circuit analysis, using an electrical analog, was developed for the initial design of the actuator. A neodymium-iron-boron material with energy density of 278 T-kA/m (35 MGOe) was selected to supply the magnetic field. The effect of changes in the design parameters of core diameter, shell outer diameter, pole face length, and coil wire layers were investigated. An extensive three-dimensional finite element analysis was carried out to accurately determine linearity with regard to axial position of the coil and coil current levels. The actuator was constructed and tested on a universal testing machine. Example plots are shown, indicating good linearity over the stroke of approximately 5.08 cm (2 in) and a range of coil currents from -1.5 A to +1.5 A. The actuator was then used for the microgravity vibration isolation experiments, described elsewhere.

Foot use during vertical climbing in chimpanzees (Pan troglodytes).

PubMed

Wunderlich, R E; Ischinger, S B

2017-08-01

Upright bipedalism is a hallmark of hominin locomotion, however debates continue regarding the extent of arboreal locomotion and the nature of bipedalism practiced by early hominins. Pedal form and function play a prominent role in these debates, as the foot is the element that directly interacts with the locomotor substrate. Recent finds have substantially increased the availability of associated foot remains of early hominins and emphasized the enigmatic nature of the early evolution of human bipedalism. New discoveries of associated forefoot remains have afforded the opportunity to assess relative proportions across the forefoot of fossil hominins and illuminated the need for data on relative loading across the forefoot in extant hominoids. In order to provide functional data with which to examine the relationship between bony features and load distribution across the forefoot during climbing, we present the first analysis of plantar pressure distribution across the forefoot of chimpanzees climbing a vertical support. Chimpanzees load the medial metatarsals and first toe disproportionately during vertical climbing. Peak pressures on these elements occur at the end of stance phase during climbing and are higher than on any other elements of the foot. Toe pressures are considerably higher during vertical climbing than during knuckle-walking or movement on horizontal poles, supporting the notion that the plantarly-broad and dorsally-narrow metatarsal heads in chimpanzees and some early hominins are associated with close-packing of the metatarsophalangeal joint during climbing. Copyright © 2017 Elsevier Ltd. All rights reserved.

Three-dimensional finite element analysis of vertical and angular misfit in implant-supported fixed prostheses.

PubMed

Assunção, Wirley Gonçalves; Gomes, Erica Alves; Rocha, Eduardo Passos; Delben, Juliana Aparecida

2011-01-01

Three-dimensional finite element analysis was used to evaluate the effect of vertical and angular misfit in three-piece implant-supported screw-retained fixed prostheses on the biomechanical response in the peri-implant bone, implants, and prosthetic components. Four three-dimensional models were fabricated to represent a right posterior mandibular section with one implant in the region of the second premolar (2PM) and another in the region of the second molar (2M). The implants were splinted by a three-piece implant-supported metal-ceramic prosthesis and differed according to the type of misfit, as represented by four different models: Control = prosthesis with complete fit to the implants; UAM (unilateral angular misfit) = prosthesis presenting unilateral angular misfit of 100 μm in the mesial region of the 2M; UVM (unilateral vertical misfit) = prosthesis presenting unilateral vertical misfit of 100 μm in the mesial region of the 2M; and TVM (total vertical misfit) = prosthesis presenting total vertical misfit of 100 μm in the platform of the framework in the 2M. A vertical load of 400 N was distributed and applied on 12 centric points by the software Ansys, ie, a vertical load of 150 N was applied to each molar in the prosthesis and a vertical load of 100 N was applied at the 2PM. The stress values and distribution in peri-implant bone tissue were similar for all groups. The models with misfit exhibited different distribution patterns and increased stress magnitude in comparison to the control. The highest stress values in group UAM were observed in the implant body and retention screw. The groups UVM and TVM exhibited high stress values in the platform of the framework and the implant hexagon, respectively. The three types of misfit influenced the magnitude and distribution of stresses. The influence of misfit on peri-implant bone tissue was modest. Each type of misfit increased the stress values in different regions of the system.

Organic non-volatile resistive photo-switches for flexible image detector arrays.

PubMed

Nau, Sebastian; Wolf, Christoph; Sax, Stefan; List-Kratochvil, Emil J W

2015-02-01

A unique implementation of an organic image detector using resistive photo-switchable pixels is presented. This resistive photo-switch comprises the vertical integration of an organic photodiode and an organic resistive switching memory element. The photodiodes act as a photosensitive element while the resistive switching elements simultaneously store the detected light information. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Generator and Setup for Emulating Exposures of Biological Samples to Lightning Strokes.

PubMed

Rebersek, Matej; Marjanovic, Igor; Begus, Samo; Pillet, Flavien; Rols, Marie-Pierre; Miklavcic, Damijan; Kotnik, Tadej

2015-10-01

We aimed to develop a system for controlled exposure of biological samples to conditions they experience when lightning strikes their habitats. We based the generator on a capacitor charged via a bridge rectifier and a dc-dc converter, and discharged via a relay, delivering arcs similar to natural lightning strokes in electric current waveform and similarly accompanied by acoustic shock waves. We coupled the generator to our exposure chamber described previously, measured electrical and acoustic properties of arc discharges delivered, and assessed their ability to inactivate bacterial spores. Submicrosecond discharges descended vertically from the conical emitting electrode across the air gap, entering the sample centrally and dissipating radially toward the ring-shaped receiving electrode. In contrast, longer discharges tended to short-circuit the electrodes. Recording at 341 000 FPS with Vision Research Phantom v2010 camera revealed that initial arc descent was still vertical, but became accompanied by arcs leaning increasingly sideways; after 8-12 μs, as the first of these arcs formed direct contact with the receiving electrode, it evolved into a channel of plasmified air and short-circuited the electrodes. We eliminated this artefact by incorporating an insulating cylinder concentrically between the electrodes, precluding short-circuiting between them. While bacterial spores are highly resistant to electric pulses delivered through direct contact, we showed that with arc discharges accompanied by an acoustic shock wave, spore inactivation is readily obtained. The presented system allows scientific investigation of effects of arc discharges on biological samples. This system will allow realistic experimental studies of lightning-triggered horizontal gene transfer and assessment of its role in evolution.

Behaviour and buoyancy regulation in the deepest-diving reptile: the leatherback turtle.

PubMed

Fossette, Sabrina; Gleiss, Adrian C; Myers, Andy E; Garner, Steve; Liebsch, Nikolai; Whitney, Nicholas M; Hays, Graeme C; Wilson, Rory P; Lutcavage, Molly E

2010-12-01

In the face of the physical and physiological challenges of performing breath-hold deep dives, marine vertebrates have evolved different strategies. Although behavioural strategies in marine mammals and seabirds have been investigated in detail, little is known about the deepest-diving reptile - the leatherback turtle (Dermochelys coriacea). Here, we deployed tri-axial accelerometers on female leatherbacks nesting on St Croix, US Virgin Islands, to explore their diving strategy. Our results show a consistent behavioural pattern within dives among individuals, with an initial period of active swimming at relatively steep descent angles (∼-40 deg), with a stroke frequency of 0.32 Hz, followed by a gliding phase. The depth at which the gliding phase began increased with the maximum depth of the dives. In addition, descent body angles and vertical velocities were higher during deeper dives. Leatherbacks might thus regulate their inspired air-volume according to the intended dive depth, similar to hard-shelled turtles and penguins. During the ascent, turtles actively swam with a stroke frequency of 0.30 Hz but with a low vertical velocity (∼0.40 ms(-1)) and a low pitch angle (∼+26 deg). Turtles might avoid succumbing to decompression sickness ('the bends') by ascending slowly to the surface. In addition, we suggest that the low body temperature of this marine ectotherm compared with that of endotherms might help reduce the risk of bubble formation by increasing the solubility of nitrogen in the blood. This physiological advantage, coupled with several behavioural and physical adaptations, might explain the particular ecological niche the leatherback turtle occupies among marine reptiles.

Circuit board routing attachment for Fermilab Gerber plotter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lindenmeyer, C.

1984-05-10

A new and potentially important method of producing large circuit boards has been developed at Fermilab. A Gerber Flat Bed Plotter with an active area of 5' x 16' has been fitted with a machining head to produce a circuit board without the use of photography or chemicals. The modifications of the Gerber Plotter do not impair its use as a photoplotter or pen plotter, the machining head is merely exchanged with the standard attachments. The modifications to the program are minimal; this will be described in another report. The machining head is fitted with an air bearing motorized spindlemore » driven at a speed of 40,000 rpm to 90,000 rpm. The spindle also is provided with air bearings on its outside diameter, offering frictionless vertical travel guidance. Vertical travel of the spindle is driven by a spring return single acting air cylinder. An adjustable hydraulic damper slows the spindle travel near the end of its downward stroke. Two programmable stops control spindle down stroke position, and limit switches are provided for position feedback to the control system. A vacuum system collects chips at the cutter head. No lubrication or regular maintenance is required. The circuit board to be fabricated is supported on a porous plastic mat which allows table vacuum to hold the board in place while allowing the cutters or drills to cut through the board without damaging the rubber platen of the plotter. The perimeter of the board must be covered to the limits of the table vacuum area used to prevent excessive leakage.« less

Kinematic control of aerodynamic forces on an inclined flapping wing with asymmetric strokes.

PubMed

Park, Hyungmin; Choi, Haecheon

2012-03-01

In the present study, we conduct an experiment using a one-paired dynamically scaled model of an insect wing, to investigate how asymmetric strokes with different wing kinematic parameters are used to control the aerodynamics of a dragonfly-like inclined flapping wing in still fluid. The kinematic parameters considered are the angles of attack during the mid-downstroke (α(md)) and mid-upstroke (α(mu)), and the duration (Δτ) and time of initiation (τ(p)) of the pitching rotation. The present dragonfly-like inclined flapping wing has the aerodynamic mechanism of unsteady force generation similar to those of other insect wings in a horizontal stroke plane, but the detailed effect of the wing kinematics on the force control is different due to the asymmetric use of the angle of attack during the up- and downstrokes. For example, high α(md) and low α(mu) produces larger vertical force with less aerodynamic power, and low α(md) and high α(mu) is recommended for horizontal force (thrust) production. The pitching rotation also affects the aerodynamics of a flapping wing, but its dynamic rotational effect is much weaker than the effect from the kinematic change in the angle of attack caused by the pitching rotation. Thus, the influences of the duration and timing of pitching rotation for the present inclined flapping wing are found to be very different from those for a horizontal flapping wing. That is, for the inclined flapping motion, the advanced and delayed rotations produce smaller vertical forces than the symmetric one and the effect of pitching duration is very small. On the other hand, for a specific range of pitching rotation timing, delayed rotation requires less aerodynamic power than the symmetric rotation. As for the horizontal force, delayed rotation with low α(md) and high α(mu) is recommended for long-duration flight owing to its high efficiency, and advanced rotation should be employed for hovering flight for nearly zero horizontal force. The present study suggests that manipulating the angle of attack during a flapping cycle is the most effective way to control the aerodynamic forces and corresponding power expenditure for a dragonfly-like inclined flapping wing.

[Particle pollution effects on the risk of cardiovascular diseases].

PubMed

Massamba, V K; Coppieters, Y; Mercier, G; Collart, P; Levêque, A

2014-02-01

The effects of air pollution on health are quite well-documented and the influence of particulate pollution on morbidity and mortality from myocardial infarction and stroke is increasingly evident. The objective of this literature review is to identify and synthesize articles on the impact of air pollution by PM10 and PM2.5 of myocardial infarction and stroke. A total of 14 studies were reported on the effects of PM10 and five on the effects of PM2.5. Nine out of 14 studies for PM10 and two studies of five for PM2.5 have found a significant association with myocardial infarction and/or stroke. Particle composition according to location, study period and population must be considered in interpreting the results on the health effects of air pollution. The integration of these elements is important for decision making in tune with social and economic conditions specific to each environment. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Structural-Thermal-Optical Program (STOP)

NASA Technical Reports Server (NTRS)

Lee, H. P.

1972-01-01

A structural thermal optical computer program is developed which uses a finite element approach and applies the Ritz method for solving heat transfer problems. Temperatures are represented at the vertices of each element and the displacements which yield deformations at any point of the heated surface are interpolated through grid points.

Interactions between exogenous rare earth elements and phosphorus leaching in packed soil columns

USDA-ARS?s Scientific Manuscript database

Rare earth elements (REEs) increasingly used in agriculture as an amendment for crop growth may help to lessen environmental losses of phosphorus (P) from heavily fertilized soils. The vertical transport characteristics of P and REEs, lanthanum (La), neodymium (Nd), samarium (Sm), and cerium (Ce), w...

MOFAT: A TWO-DIMENSIONAL FINITE ELEMENT PROGRAM FOR MULTIPHASE FLOW AND MULTICOMPONENT TRANSPORT - PROGRAM DOCUMENTATION AND USER'S GUIDE

EPA Science Inventory

This manual describes a two-dimensional, finite element model for coupled multiphase flow and multicomponent transport in planar or radially symmetric vertical sections. low and transport of three fluid phases, including water, nonaqueous phase liquid (NAPL), and gas are consider...

High Performance Amplifier Element Realization via MoS2/GaTe Heterostructures.

PubMed

Yan, Xiao; Zhang, David Wei; Liu, Chunsen; Bao, Wenzhong; Wang, Shuiyuan; Ding, Shijin; Zheng, Gengfeng; Zhou, Peng

2018-04-01

2D layered materials (2DLMs), together with their heterostructures, have been attracting tremendous research interest in recent years because of their unique physical and electrical properties. A variety of circuit elements have been made using mechanically exfoliated 2DLMs recently, including hard drives, detectors, sensors, and complementary metal oxide semiconductor field-effect transistors. However, 2DLM-based amplifier circuit elements are rarely studied. Here, the integration of 2DLMs with 3D bulk materials to fabricate vertical junction transistors with current amplification based on a MoS 2 /GaTe heterostructure is reported. Vertical junction transistors exhibit the typical current amplification characteristics of conventional bulk bipolar junction transistors while having good current transmission coefficients (α ∼ 0.95) and current gain coefficient (β ∼ 7) at room temperature. The devices provide new attractive prospects in the investigation of 2DLM-based integrated circuits based on amplifier circuits.

High Performance Amplifier Element Realization via MoS2/GaTe Heterostructures

PubMed Central

Yan, Xiao; Zhang, David Wei; Liu, Chunsen; Bao, Wenzhong; Wang, Shuiyuan; Ding, Shijin; Zheng, Gengfeng

2018-01-01

Abstract 2D layered materials (2DLMs), together with their heterostructures, have been attracting tremendous research interest in recent years because of their unique physical and electrical properties. A variety of circuit elements have been made using mechanically exfoliated 2DLMs recently, including hard drives, detectors, sensors, and complementary metal oxide semiconductor field‐effect transistors. However, 2DLM‐based amplifier circuit elements are rarely studied. Here, the integration of 2DLMs with 3D bulk materials to fabricate vertical junction transistors with current amplification based on a MoS2/GaTe heterostructure is reported. Vertical junction transistors exhibit the typical current amplification characteristics of conventional bulk bipolar junction transistors while having good current transmission coefficients (α ∼ 0.95) and current gain coefficient (β ∼ 7) at room temperature. The devices provide new attractive prospects in the investigation of 2DLM‐based integrated circuits based on amplifier circuits. PMID:29721428

Effect of solid distribution on elastic properties of open-cell cellular solids using numerical and experimental methods.

PubMed

Zargarian, A; Esfahanian, M; Kadkhodapour, J; Ziaei-Rad, S

2014-09-01

Effect of solid distribution between edges and vertices of three-dimensional cellular solid with an open-cell structure was investigated both numerically and experimentally. Finite element analysis (FEA) with continuum elements and appropriate periodic boundary condition was employed to calculate the elastic properties of cellular solids using tetrakaidecahedral (Kelvin) unit cell. Relative densities between 0.01 and 0.1 and various values of solid fractions were considered. In order to validate the numerical model, three scaffolds with the relative density of 0.08, but different amounts of solid in vertices, were fabricated via 3-D printing technique. Good agreement was observed between numerical simulation and experimental results. Results of numerical simulation showed that, at low relative densities (<0.03), Young׳s modulus increased by shifting materials away from edges to vertices at first and then decreased after reaching a critical point. However, for the high values of relative density, Young׳s modulus increased monotonically. Mechanisms of such a behavior were discussed in detail. Results also indicated that Poisson׳s ratio decreased by increasing relative density and solid fraction in vertices. By fitting a curve to the data obtained from the numerical simulation and considering the relative density and solid fraction in vertices, empirical relations were derived for Young׳s modulus and Poisson׳s ratio. Copyright © 2014 Elsevier Ltd. All rights reserved.

Strokes are possible complications of cannabinoids use.

PubMed

Wolff, Valérie; Jouanjus, Emilie

2017-05-01

It is critically important to identify all factors that may play a role in the recent increase of the incidence of stroke among the young population. Considering the worldwide use of cannabinoids (cannabis and synthetic cannabinoids), the recent legalization of their consumption in some countries, and their supposed involvement in cardiovascular events, we evaluated their role in the occurrence of neurovascular complications among the young. Ninety-eight patients were described in the literature as having a cannabinoids-related stroke (85 after cannabis use and 13 after synthetic cannabinoids). The distribution by type of stroke was as follows: 4 patients with an undetermined type of stroke, 85 with an ischemic stroke and/or a transient ischemic attack, and 9 with a hemorrhagic stroke. The mean age of patients was 32.3±11.8years (range 15-63), and the majority of them were male with a sex ratio of 3.7:1. Cannabis was often smoked with tobacco in 66% of cases. Most of the patients with cannabinoids-related strokes were chronic cannabis users in 81% of cases, and for 18% of them, there was a recent increase of the amount of cannabis consumption during the days before the occurrence of stroke. Even if the prognosis of stroke was globally favorable in 46% of cases, with no or few sequelae, 5 patients died after the neurovascular event. One striking element reported in the majority of the reports was a temporal relationship between cannabinoids use, whether natural or synthetic, and the occurrence of stroke. However, a temporal correlation does not mean causation, and other factors may be involved. Cannabis may be considered as a risk factor of stroke until research shows evidence of an underlying mechanism that, alone or in association with others, contributes to the development of stroke. As of today, reversible cerebral vasoconstriction triggered by cannabinoids use may be a convincing mechanism of stroke in 27% of cases. Indeed, despite the widespread use of cannabinoids, the low frequency of neurovascular complications after their use may be due to a genetic predisposition to their neurovascular toxicity in some individuals. Further studies should focus on this point. More importantly however, this low frequency may be underestimated because the drug consumption may not be systematically researched, neither by questioning nor by laboratory screening. Besides this vascular role of cannabinoids in the occurrence of stroke, a cellular effect of cannabis on brain mitochondria was recently suggested in an experimental study. One of the mechanisms involved in young cannabis users with stroke may be the generation of reactive oxygen species leading to an oxidative stress, which is a known mechanism in stroke in humans. It is useful to inform the young population about the real potential risk of using cannabinoids. We suggest to systematically ask all young adults with stroke about their drug consumption including cannabinoids, to screen urine for cannabis or to include a specific diagnostic test to detect synthetic cannabinoids, and to obtain non-invasive intracranial arterial investigations (i.e. CT-angiography or cerebral MRA) in order to search for cerebral vasoconstriction. However, several questions remained unresolved and further research is still needed to assess the pathophysiological mechanisms involved in young cannabinoids users with stroke. This article is part of a Special Issue entitled "Cannabinoids and Epilepsy". Copyright © 2017 Elsevier Inc. All rights reserved.

Loading differences in single-leg landing in the forehand- and backhand-side courts after an overhead stroke in badminton: A novel tri-axial accelerometer research.

PubMed

Sasaki, Shogo; Nagano, Yasuharu; Ichikawa, Hiroshi

2018-05-10

Anterior cruciate ligament (ACL) injuries in badminton commonly occur during single-leg landing after an overhead stroke in the backhand-side court. This study compared differences in trunk acceleration and kinematic variables during single-leg landing in the forehand- and backhand-side courts after an overhead stroke. Eighteen female junior badminton players performed two singles games while wearing a tri-axial accelerometer. The moment that over 4g of resultant acceleration was generated was determined using synchronised video cameras. Trunk lateral inclination and hip abduction angles at the point of landing with over 4g of resultant acceleration were analysed. Mediolateral acceleration in the backhand-side court was greater than that in the opposite-side court (p < 0.001, ES = 0.840). Both trunk lateral angles were larger than those previously reported in injured participants and the hip abduction angle in the backhand-side court was larger than that in the forehand-side court (p < 0.001, ES = 2.357). The lateral and vertical acceleration in the backhand-side court showed moderate-to-strong correlations with the trunk and hip angles. The mediolateral physical demand and high-risk posture in the backhand-side court may be associated with a higher incidence of knee injuries during badminton games.

Relationship between severity of shoulder subluxation and soft-tissue injury in hemiplegic stroke patients.

PubMed

Huang, Shih-Wei; Liu, Sen-Yung; Tang, Hao-Wei; Wei, Ta-Sen; Wang, Wei-Te; Yang, Chao-Pin

2012-09-01

The aims of this study were: (i) to determine whether the severity of post-hemiplegic shoulder subluxation in stroke patients correlates with soft-tissue injury; and (ii) to determine the shoulder subluxation measurement cut-off points that are indications for further ultrasound examination for soft-tissue injuries in these patients. Cross-sectional study. A total of 39 stroke patients with shoulder subluxation. Shoulder subluxation was evaluated by physical examination, radiography and ultrasound. Soft-tissue injuries were assessed by ultrasound. Subluxation parameters were entered into stepwise logistic regression analyses to predict biceps and supraspinatus tendonitis. With the assumption that shoulder subluxation can be a predisposing factor for tendonitis, receiver operating characteristic curves for shoulder subluxation parameters of the affected side were used to determine cut-off points for optimal sensitivity and specificity of biceps and supraspinatus tendonitis. Shoulder subluxation lateral distance, measured by physical examination, is a predictor for supraspinatus tendonitis (odds ratio = 34.9, p = 0.036). Further ultrasound investigation for soft-tissue injury is indicated when subluxation lateral distance, measured by physical examination is ≥ 2.25 cm or, measured by radiographic examination, ≥ 3.18 cm for lateral distance, ≥ 3.08 cm for vertical distance, or ≥ 2.65 cm for horizontal distance. When post-hemiplegic shoulder subluxation measurements exceed the above-mentioned cut-off points in physical or radiographic examinations, further ultrasound evaluation for soft-tissue injury is recommended.

Abdominally implanted transmitters with percutaneous antennas affect the dive performance of Common Eiders

USGS Publications Warehouse

Powell, Abby N.; Latty, Christopher J.; Hollmén, Tuula E.; Petersen, Margaret R.; Andrews, Russel D.

2010-01-01

Implanted transmitters have become an important tool for studying the ecology of sea ducks, but their effects remain largely undocumented. To address this, we assessed how abdominally implanted transmitters with percutaneous antennas affect the vertical dive speeds, stroke frequencies, bottom time, and dive duration of captive Common Eiders (Somateria mollissima). To establish baselines, we recorded video of six birds diving 4.9 m prior to surgery, implanted them with 38- to 47-g platform transmitter terminals, and then recorded their diving for 3.5 months after surgery to determine effects. Descent speeds were 16–25% slower and ascent speeds were 17–44% slower after surgery, and both remained below baseline at the end of the study. Dive durations were longer than baseline until day 22. On most days between 15 and 107 days after surgery, foot-stroke frequencies of birds foraging on the bottom were slower. Foot- and wing-stroke frequencies during descent and bottom time did not differ across the time series. If birds that rely on benthic invertebrates for sustenance dive slower and stay submerged longer after being implanted with a satellite transmitter, their foraging energetics may be affected. Researchers considering use of implanted transmitters with percutaneous antennas should be mindful of these effects and the possibility of concomitant alterations in diving behavior, foraging success, and migratory behavior compared to those of unmarked conspecifics.

PIV measurements of in-cylinder, large-scale structures in a water-analogue Diesel engine

NASA Astrophysics Data System (ADS)

Kalpakli Vester, A.; Nishio, Y.; Alfredsson, P. H.

2016-11-01

Swirl and tumble are large-scale structures that develop in an engine cylinder during the intake stroke. Their structure and strength depend on the design of the inlet ports and valves, but also on the valve lift history. Engine manufacturers make their design to obtain a specific flow structure that is assumed to give the best engine performance. Despite many efforts, there are still open questions, such as how swirl and tumble depend on the dynamics of the valves/piston as well as how cycle-to-cycle variations should be minimized. In collaboration with Swedish vehicle industry we perform PIV measurements of the flow dynamics during the intake stroke inside a cylinder of a water-analogue engine model having the same geometrical characteristics as a typical truck Diesel engine. Water can be used since during the intake stroke the flow is nearly incompressible. The flow from the valves moves radially outwards, hits the vertical walls of the cylinder, entrains surrounding fluid, moves along the cylinder walls and creates a central backflow, i.e. a tumble motion. Depending on the port and valve design and orientation none, low, or high swirl can be established. For the first time, the effect of the dynamic motion of the piston/valves on the large-scale structures is captured. Supported by the Swedish Energy Agency, Scania CV AB and Volvo GTT, through the FFI program.

Effects of Brain-Computer Interface-controlled Functional Electrical Stimulation Training on Shoulder Subluxation for Patients with Stroke: A Randomized Controlled Trial.

PubMed

Jang, Yun Young; Kim, Tae Hoon; Lee, Byoung Hee

2016-06-01

The purpose of this study was to investigate the effects of brain-computer interface (BCI)-controlled functional electrical stimulation (FES) training on shoulder subluxation of patients with stroke. Twenty subjects were randomly divided into two groups: the BCI-FES group (n = 10) and the FES group (n = 10). Patients in the BCI-FES group were administered conventional therapy with the BCI-FES on the shoulder subluxation area of the paretic upper extremity, five times per week during 6 weeks, while the FES group received conventional therapy with FES only. All patients were assessed for shoulder subluxation (vertical distance, VD; horizontal distance, HD), pain (visual analogue scale, VAS) and the Manual Function Test (MFT) at the time of recruitment to the study and after 6 weeks of the intervention. The BCI-FES group demonstrated significant improvements in VD, HD, VAS and MFT after the intervention period, while the FES group demonstrated significant improvements in HD, VAS and MFT. There were also significant differences in the VD and two items (shoulder flexion and abduction) of the MFT between the two groups. The results of this study suggest that BCI-FES training may be effective in improving shoulder subluxation of patients with stroke by facilitating motor recovery. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Feasibility and effects of newly developed balance control trainer for mobility and balance in chronic stroke patients: a randomized controlled trial.

PubMed

Lee, So Hyun; Byun, Seung Deuk; Kim, Chul Hyun; Go, Jin Young; Nam, Hyeon Uk; Huh, Jin Seok; Jung, Tae Du

2012-08-01

To investigate the feasibility and effects of balance training with a newly developed Balance Control Trainer (BCT) that applied the concept of vertical movement for the improvements of mobility and balance in chronic stroke patients. Forty chronic stroke patients were randomly assigned to an experimental or a control group. The experimental group (n=20) underwent training with a BCT for 20 minutes a day, 5 days a week for 4 weeks, in addition to concurrent conventional physical therapy. The control group (n=20) underwent only conventional therapy for 4 weeks. All participants were assessed by: the Functional Ambulation Categories (FAC), 10-meter Walking Test (10mWT), Timed Up and Go test (TUG), Berg Balance Scale (BBS), Korean Modified Barthel Index (MBI), and Manual Muscle Test (MMT) before training, and at 2 and 4 weeks of training. There were statistically significant improvements in all parameters except knee extensor power at 2 weeks of treatment, and in all parameters except MBI which showed further statistically significant progress in the experimental group over the next two weeks (p<0.05). Statistically significant improvements on all measurements were observed in the experimental group after 4 weeks total. Comparing the two groups at 2 and 4 weeks of training respectively, 10mWT, TUG, and BBS showed statistically more significant improvements in the experimental group (p<0.05). Balance training with a newly developed BCT is feasible and may be an effective tool to improve balance and gait in ambulatory chronic stroke patients. Furthermore, it may provide additional benefits when used in conjunction with conventional therapies.

Northern elephant seals adjust gliding and stroking patterns with changes in buoyancy: validation of at-sea metrics of body density.

PubMed

Aoki, Kagari; Watanabe, Yuuki Y; Crocker, Daniel E; Robinson, Patrick W; Biuw, Martin; Costa, Daniel P; Miyazaki, Nobuyuki; Fedak, Mike A; Miller, Patrick J O

2011-09-01

Many diving animals undergo substantial changes in their body density that are the result of changes in lipid content over their annual fasting cycle. Because the size of the lipid stores reflects an integration of foraging effort (energy expenditure) and foraging success (energy assimilation), measuring body density is a good way to track net resource acquisition of free-ranging animals while at sea. Here, we experimentally altered the body density and mass of three free-ranging elephant seals by remotely detaching weights and floats while monitoring their swimming speed, depth and three-axis acceleration with a high-resolution data logger. Cross-validation of three methods for estimating body density from hydrodynamic gliding performance of freely diving animals showed strong positive correlation with body density estimates obtained from isotope dilution body composition analysis over density ranges of 1015 to 1060 kg m(-3). All three hydrodynamic models were within 1% of, but slightly greater than, body density measurements determined by isotope dilution, and therefore have the potential to track changes in body condition of a wide range of freely diving animals. Gliding during ascent and descent clearly increased and stroke rate decreased when buoyancy manipulations aided the direction of vertical transit, but ascent and descent speed were largely unchanged. The seals adjusted stroking intensity to maintain swim speed within a narrow range, despite changes in buoyancy. During active swimming, all three seals increased the amplitude of lateral body accelerations and two of the seals altered stroke frequency in response to the need to produce thrust required to overcome combined drag and buoyancy forces.

Lightning Magnetic Field Measurements around Langmuir Laboratory

NASA Astrophysics Data System (ADS)

Stock, M.; Krehbiel, P. R.; Rison, W.; Aulich, G. D.; Edens, H. E.; Sonnenfeld, R. G.

2010-12-01

In the absence of artificial conductors, underground lightning transients are produced by diffusion of the horizontal surface magnetic field of a return stroke vertically downward into the conducting earth. The changing magnetic flux produces an orthogonal horizontal electric field, generating a dispersive, lossy transverse electromagnetic wave that penetrates a hundred meters or more into the ground according to the skin depth of the medium. In turn, the electric field produces currents that flow toward or away from the channel to ground depending on the stroke polarity. The underground transients can produce large radial horizontal potential gradients depending on the distance from the discharge and depth below the surface. In this study we focus on the surface excitation field. The goal of the work is to compare measurements of surface magnetic field waveforms B(t) at different distances from natural lightning discharges with simple and detailed models of the return stroke fields. In addition to providing input to the diffusion mechanism, the results should aid in further understanding return stroke field generation processes. The observational data are to be obtained using orthogonal sets of straightened Rogowski coils to measure magnetic field waveforms in N-S and E-W directions. The waveforms are sampled at 500 kS/s over 1.024 second time intervals and recorded directly onto secure digital cards. The instrument operates off of battery power for several days or weeks at a time in remote, unattended locations and measures magnetic field strengths of up to several tens of amperes/meter. The observations are being made in conjunction with collocated slow electric field change measurements and under good 3-D lightning mapping array (LMA) and fast electric field change coverage.

Effect of denture cleaning on abrasion resistance and surface topography of polymerized CAD CAM acrylic resin denture base

PubMed Central

Shinawi, Lana Ahmed

2017-01-01

Background The application of computer-aided design computer-aided manufacturing (CAD CAM) technology in the fabrication of complete dentures, offers numerous advantages as it provides optimum fit and eliminates polymerization shrinkage of the acrylic base. Additionally, the porosity and surface roughness of CAD CAM resins is less compared to conventionally processed resins which leads to a decrease in the adhesion of bacteria on the denture base, which is associated with many conditions including halitosis and aspiration pneumonia in elderly denture wearers. Aim To evaluate the influence of tooth brushing with dentifrices on CAD CAM resin blocks in terms of abrasion resistance, surface roughness and scanning electron photomicrography. Methods This experimental study was carried out at the Faculty of Dentistry of King Abdulaziz University during 2016. A total of 40 rectangular shaped polymerized CAD CAM resin samples were subjected to 40.000 and 60.000 brushing strokes under a 200-gram vertical load simulating three years of tooth brushing strokes using commercially available denture cleaning dentifrice. Data were analyzed by SPSS version 20, using descriptive statistics and ANOVA. Results ANOVA test revealed a statistical significant weight loss of CAD CAM acrylic resin denture base specimens following 40.000 and 60.000 brushing strokes as well as a statistical significant change (p=0.0.5) in the surface roughness following brushing. The CAD CAM resin samples SEM baseline imaging revealed a relatively smooth homogenous surface, but following 40,000 and 60,000 brushing strokes, imaging displayed the presence of small scratches on the surface. Conclusion CAD CAM resin displayed a homogenous surface initially with low surface roughness that was significantly affected following simulating three years of manual brushing, but despite the significant weight loss, the findings are within the clinically acceptable limits. PMID:28713496

Effect of denture cleaning on abrasion resistance and surface topography of polymerized CAD CAM acrylic resin denture base.

PubMed

Shinawi, Lana Ahmed

2017-05-01

The application of computer-aided design computer-aided manufacturing (CAD CAM) technology in the fabrication of complete dentures, offers numerous advantages as it provides optimum fit and eliminates polymerization shrinkage of the acrylic base. Additionally, the porosity and surface roughness of CAD CAM resins is less compared to conventionally processed resins which leads to a decrease in the adhesion of bacteria on the denture base, which is associated with many conditions including halitosis and aspiration pneumonia in elderly denture wearers. To evaluate the influence of tooth brushing with dentifrices on CAD CAM resin blocks in terms of abrasion resistance, surface roughness and scanning electron photomicrography. This experimental study was carried out at the Faculty of Dentistry of King Abdulaziz University during 2016. A total of 40 rectangular shaped polymerized CAD CAM resin samples were subjected to 40.000 and 60.000 brushing strokes under a 200-gram vertical load simulating three years of tooth brushing strokes using commercially available denture cleaning dentifrice. Data were analyzed by SPSS version 20, using descriptive statistics and ANOVA. ANOVA test revealed a statistical significant weight loss of CAD CAM acrylic resin denture base specimens following 40.000 and 60.000 brushing strokes as well as a statistical significant change (p=0.0.5) in the surface roughness following brushing. The CAD CAM resin samples SEM baseline imaging revealed a relatively smooth homogenous surface, but following 40,000 and 60,000 brushing strokes, imaging displayed the presence of small scratches on the surface. CAD CAM resin displayed a homogenous surface initially with low surface roughness that was significantly affected following simulating three years of manual brushing, but despite the significant weight loss, the findings are within the clinically acceptable limits.

Neural control of arm movements reveals a tendency to use gravity to simplify joint coordination rather than to decrease muscle effort.

PubMed

Wang, Wanyue; Dounskaia, Natalia

2016-12-17

How gravity influences neural control of arm movements remains under debate. We tested three alternative interpretations suggested by previous research: (1) that muscular control includes two components, tonic which compensates for gravity and phasic which produces the movement; (2) that there is a tendency to exploit gravity to reduce muscle effort; and (3) that there is a tendency to use a trailing pattern of joint control during which either the shoulder or elbow is rotated actively and the other joint rotates predominantly passively, and to exploit gravity for control of the passively rotated joint. A free-stroke drawing task was performed that required production of center-out strokes within a circle while selecting stroke directions randomly. The circle was positioned in the horizontal, sagittal, and frontal plane. The arm joints freely rotated in space. In each plane, the distribution of the strokes across directions was non-uniform. Directional histograms were built and their peaks were used to identify preferred movement directions. The directional preferences were especially pronounced in the two vertical planes. The upward directions were most preferred. To test the three interpretations, we used a kinetic analysis that determined the role of gravitational torque in the production of movement in the preferred directions. The results supported the third interpretation and provided evidence against the first and second interpretation. The trailing pattern has been associated with reduced neural effort for joint coordination, and therefore, we conclude that the major tendency with respect to gravity is to exploit it for simplification of joint coordination. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

Effect of framework material and vertical misfit on stress distribution in implant-supported partial prosthesis under load application: 3-D finite element analysis.

PubMed

Bacchi, Ataís; Consani, Rafael Leonardo Xediek; Mesquita, Marcelo Ferraz; Dos Santos, Mateus Bertolini Fernandes

2013-09-01

This study evaluated the influence of framework material and vertical misfit on stress created in an implant-supported partial prosthesis under load application. The posterior part of a severely reabsorbed jaw with a fixed partial prosthesis above two osseointegrated titanium implants at the place of the second premolar and second molar was modeled using SolidWorks 2010 software. Finite element models were obtained by importing the solid model into an ANSYS Workbench 11 simulation. The models were divided into 15 groups according to their prosthetic framework material (type IV gold alloy, silver-palladium alloy, commercially pure titanium, cobalt-chromium alloy or zirconia) and vertical misfit level (10 µm, 50 µm and 100 µm). After settlement of the prosthesis with the closure of the misfit, simultaneous loads of 110 N vertical and 15 N horizontal were applied on the occlusal and lingual faces of each tooth, respectively. The data was evaluated using Maximum Principal Stress (framework, porcelain veneer and bone tissue) and a von Mises Stress (retention screw) provided by the software. As a result, stiffer frameworks presented higher stress concentrations; however, these frameworks led to lower stresses in the porcelain veneer, the retention screw (faced to 10 µm and 50 µm of the misfit) and the peri-implant bone tissues. The increase in the vertical misfit resulted in stress values increasing in all of the prosthetic structures and peri-implant bone tissues. The framework material and vertical misfit level presented a relevant influence on the stresses for all of the structures evaluated.

Stress distribution in fixed-partial prosthesis and peri-implant bone tissue with different framework materials and vertical misfit levels: a three-dimensional finite element analysis.

PubMed

Bacchi, Ataís; Consani, Rafael L X; Mesquita, Marcelo F; dos Santos, Mateus B F

2013-09-01

The purpose of this study was to evaluate the influence of superstructure material and vertical misfits on the stresses created in an implant-supported partial prosthesis. A three-dimensional (3-D) finite element model was prepared based on common clinical data. The posterior part of a severely resorbed jaw with two osseointegrated implants at the second premolar and second molar regions was modeled using specific modeling software (SolidWorks 2010). Finite element models were created by importing the solid model into mechanical simulation software (ANSYS Workbench 11). The models were divided into groups according to the prosthesis framework material (type IV gold alloy, silver-palladium alloy, commercially pure titanium, cobalt-chromium alloy, or zirconia) and vertical misfit level (10 µm, 50 µm, and 100 µm) created at one implant-prosthesis interface. The gap of the vertical misfit was set to be closed and the stress values were measured in the framework, porcelain veneer, retention screw, and bone tissue. Stiffer materials led to higher stress concentration in the framework and increased stress values in the retention screw, while in the same circumstances, the porcelain veneer showed lower stress values, and there was no significant difference in stress in the peri-implant bone tissue. A considerable increase in stress concentration was observed in all the structures evaluated within the misfit amplification. The framework material influenced the stress concentration in the prosthetic structures and retention screw, but not that in bone tissue. All the structures were significantly influenced by the increase in the misfit levels.

Biomechanical characteristics of self-ligating brackets in a vertically displaced canine model: a finite element analysis.

PubMed

Kim, S-J; Kwon, Y-H; Hwang, C-J

2016-05-01

The objective of this study was to compare the biomechanical characteristics between two types of self-ligating brackets and conventional metal brackets using finite element analysis of a vertically displaced canine model focusing on the desired force on the canine and undesirable forces on adjacent teeth. Three-dimensional finite element models of the maxillary dentition with 1-mm, 2-mm, and 3-mm vertically displaced canines were constructed. Two different self-ligating brackets (In-Ovation C and Smart clip) and a conventional metal bracket (Micro-arch) were modeled. After a 0.016-inch NiTi (0.40 mm, round) wire was engaged, the displacement of each tooth was calculated using x-, y-, and z-coordinates, and the tensile and compressive stresses were calculated. The extrusion and maximal tensile stress of the canine differed little between the three brackets, but the intrusion and minimal compressive stress values of the adjacent teeth differed considerably and were highest in the Smart clip and least in the In-Ovation C. The extrusion and maximal tensile stress of the canine in the 3-mm displacement model was less than that in the 2-mm displacement model, and the intrusion and minimal compressive stress of the adjacent teeth increased with the degree of displacement. Self-ligating brackets were not superior to conventional brackets in leveling a vertically displaced canine. A continuous arch wire may not be recommended for leveling of severely displaced canines whether using self-ligating or conventional brackets. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

An investigation of improved airbag performance by vent control and gas injection

NASA Astrophysics Data System (ADS)

Lee, Calvin; Rosato, Nick; Lai, Francis

Airbags are currently being investigated as an impact energy absorber for U.S. Army airdrop. Simple airbags with constant vent areas have been found to be unsatisfactory in yielding high G forces. In this paper, a method of controlling the vent area and a method of injecting gas into the airbag during its compression stroke to improve airbag performance are presented. Theoretical analysis of complex airbags using these two methods show that they provide lower G forces than simple airbags. Vertical drop tests of a vent-control airbag confirm this result. Gas-injection airbags are currently being tested.

A model-based analysis of a display for helicopter landing approach. [control theoretical model of human pilot

NASA Technical Reports Server (NTRS)

Hess, R. A.; Wheat, L. W.

1975-01-01

A control theoretic model of the human pilot was used to analyze a baseline electronic cockpit display in a helicopter landing approach task. The head down display was created on a stroke written cathode ray tube and the vehicle was a UH-1H helicopter. The landing approach task consisted of maintaining prescribed groundspeed and glideslope in the presence of random vertical and horizontal turbulence. The pilot model was also used to generate and evaluate display quickening laws designed to improve pilot vehicle performance. A simple fixed base simulation provided comparative tracking data.

Nursing interventions for improving nutritional status and outcomes of stroke patients: descriptive reviews of processes and outcomes.

PubMed

Perry, Lin; Hamilton, Sharon; Williams, Jane; Jones, Susan

2013-02-01

Stroke produces many effects that impact eating. Nutrition is fundamental for recovery and rehabilitation, but the nursing nutritional role and associated outcomes have not been delineated. (1) To identify nursing interventions intended to improve nutritional status and related outcomes of stroke survivors, and (2) To examine the outcomes of identified nursing interventions on nutrition-related outcomes, including dietary intake, functional status, complications, activities of daily living, mortality, and quality of life for stroke survivors. A modified version of Cochrane literature searching and review methods was used to identify studies that described and evaluated nursing nutritional interventions for adult stroke patients in hospital and community settings. A minimum of 10 years content of seven databases and nine journals was searched to March 2011. Findings were presented descriptively. In total 27 papers from 26 studies were included: 5 randomized controlled trials, 5 clinical trials, 6 quasi-experiments, 4 case studies, and 6 qualitative/observational studies. Stroke nursing nutritional care encompassed screening of nutritional status and swallowing function; assessment of nutritional characteristics and preferences; referral; mealtime organization, supervision and monitoring; mealtime assistance and feeding skills. Nurses individualized care, coordinated or managed meal delivery and enteral feeding systems, were responsible for the dining environment and conduct of mealtimes; they taught staff, patients, and carers. There was little indication of integrated or psychosocial nursing nutritional care, or concepts, theories or models of nursing nutritional care. Many interventions were described but not evaluated. Little high quality evidence was of available. This review indicated the parameters of nursing nutritional care, and provided a framework for future research. A functional, supportive, and educational nursing nutritional role was described but little evidence was of sufficient quality to support policy and practice development or inform education. Nutritional care was revealed as an essential but under-recognized element of stroke nursing. © 2012 The authors. World Views on Evidence-Based Nursing © Sigma Theta Tau International.

Detail of the base of dipole antenna element with graduated ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail of the base of dipole antenna element with graduated pole, note the arms supporting the vertical wires away from the mast and the metal mesh covering the concrete base, view facing west - U.S. Naval Base, Pearl Harbor, Naval Radio Station, AF/FRD-10 Circularly Disposed Antenna Array, Wahiawa, Honolulu County, HI

Vertical profile of elemental concentrations in aerosol particles in the Bermuda area during GCE/CASE/WATOX

NASA Astrophysics Data System (ADS)

Ennis, G.; Sievering, H.

1990-06-01

During the 1988 Global Change Expedition/Coordinated Air-Sea Experiment/Western Atlantic Ocean Experiment (GCE/CASE/WATOX) joint effort, research was conducted to determine elemental concentrations in atmospheric aerosol particles near Bermuda, to construct a three-level (15, 150, and 2600 m ASL) vertical profile of these concentrations, and to ascertain the source of the particles. Samples were collected by the NOAA King Air aircraft and NOAA ship Mt. Mitchell on July 24-28, 1988. Concentration determinations were made for 16 elements through the use of an X ray fluorescence instrument designed for analysis of small-mass samples. A layering effect was found; concentrations of several elements at 150 m were more than twice their respective concentrations at 15 m and 2600 m. Enrichment factors, V/Mn ratio, and correlations between concentrations suggest a Saharan mineral source, despite air mass back trajectories that show no direct continental input for up to 10 days prior to sample collection. Estimated total mineral aerosol concentrations at 15 m, 150 m, and 2600 m are 1.5, 4.1, and 2.1 μg m-3.

Test-Analysis Correlation of a Crash Simulation of a Vertical Drop Test of a Commuter-Category Aircraft

NASA Technical Reports Server (NTRS)

Jackson, Karen E.; Fasanella, Edwin L.

2004-01-01

A finite element model of an ATR42-300 commuter-class aircraft was developed and a crash simulation was executed. Analytical predictions were correlated with data obtained from a 30-feet per second (9.14-meters per second) vertical drop test of the aircraft. The purpose of the test was to evaluate the structural response of the aircraft when subjected to a severe, but survivable, impact. The aircraft was configured with seats, dummies, luggage, and other ballast. The wings were filled with 8,700 lb. (3,946 kilograms) of water to represent the fuel. The finite element model, which consisted of 57,643 nodes and 62,979 elements, was developed from direct measurements of the airframe geometry. The seats, dummies, luggage, simulated engines and fuel, and other ballast were represented using concentrated masses. The model was executed in LS-DYNA, a commercial finite element code for performing explicit transient dynamic simulations. Analytical predictions of structural deformation and selected time-history responses were correlated with experimental data from the drop test to validate the simulation.

Experimental Evaluation of a Method for Turbocharging Four-Stroke, Single Cylinder, Internal Combustion Engines

NASA Astrophysics Data System (ADS)

Buchman, Michael; Winter, Amos

2015-11-01

Turbocharging an engine increases specific power, improves fuel economy, reduces emissions, and lowers cost compared to a naturally aspirated engine of the same power output. These advantages make turbocharging commonplace for multi-cylinder engines. Single cylinder engineers are not commonly turbocharged due to the phase lag between the exhaust stroke, which powers the turbocharger, and the intake stroke, when air is pumped into the engine. Our proposed method of turbocharging single cylinder engines is to add an ``air capacitor'' to the intake manifold, an additional volume that acts as a buffer to store compressed air between the exhaust and intake strokes, and smooth out the pressure pulses from the turbocharger. This talk presents experimental results from a single cylinder, turbocharged diesel engine fit with various sized air capacitors. Power output from the engine was measured using a dynamometer made from a generator, with the electrical power dissipated with resistive heating elements. We found that intake air density increases with capacitor size as theoretically predicted, ranging from 40 to 60 percent depending on heat transfer. Our experiment was able to produce 29 percent more power compared to using natural aspiration. These results validated that an air capacitor and turbocharger may be a simple, cost effective means of increasing the power density of single cylinder engines.

Nitric Oxide Donors as Neuroprotective Agents after an Ischemic Stroke-Related Inflammatory Reaction

PubMed Central

Rojas-Mayorquín, Argelia E.; Ortuño-Sahagún, Daniel

2013-01-01

Cerebral ischemia initiates a cascade of detrimental events including glutamate-associated excitotoxicity, intracellular calcium accumulation, formation of Reactive oxygen species (ROS), membrane lipid degradation, and DNA damage, which lead to the disruption of cellular homeostasis and structural damage of ischemic brain tissue. Cerebral ischemia also triggers acute inflammation, which exacerbates primary brain damage. Therefore, reducing oxidative stress (OS) and downregulating the inflammatory response are options that merit consideration as potential therapeutic targets for ischemic stroke. Consequently, agents capable of modulating both elements will constitute promising therapeutic solutions because clinically effective neuroprotectants have not yet been discovered and no specific therapy for stroke is available to date. Because of their ability to modulate both oxidative stress and the inflammatory response, much attention has been focused on the role of nitric oxide donors (NOD) as neuroprotective agents in the pathophysiology of cerebral ischemia-reperfusion injury. Given their short therapeutic window, NOD appears to be appropriate for use during neurosurgical procedures involving transient arterial occlusions, or in very early treatment of acute ischemic stroke, and also possibly as complementary treatment for neurodegenerative diseases such as Parkinson or Alzheimer, where oxidative stress is an important promoter of damage. In the present paper, we focus on the role of NOD as possible neuroprotective therapeutic agents for ischemia/reperfusion treatment. PMID:23691263

A novel bilateral lower extremity mirror therapy intervention for individuals with stroke.

PubMed

Crosby, Lucas D; Marrocco, Stephanie; Brown, Janet; Patterson, Kara K

2016-12-01

Despite improvements made in stroke rehabilitation, motor impairment and gait deficits persist at discharge. New interventions are needed. Mirror therapy has promise as one element of a rehabilitation program. The primary objectives were to 1) describe a bilateral, lower extremity mirror therapy (LE-MT) device and training protocol and 2) investigate the feasibility of LE-MT. A LE-MT device was constructed to train bilateral LE movements for 30 min, 3 times/week for 4 weeks, as an adjunct to physiotherapy in three individuals post-stroke. Sessions were digitally recorded and reviewed to extract feasibility measures; repetitions, rests and session duration. Pre and post measures of gait and motor impairment were taken. Two participants completed 100% of the sessions and a third completed 83% due to a recurrence of pre-existing back pain. Repetitions increased and session duration was maintained. Number of rests decreased for two participants and increased for one participant. Participants reported fatigue and mild muscle soreness but also that the intervention was tolerable. Positive gait changes included increased velocity and decreased variability. LE motor impairment also improved. A bilateral LE-MT adjunct intervention for stroke is feasible and may have positive effects. A history of low back pain should be a precaution.

Continuous stroke volume estimation from aortic pressure using zero dimensional cardiovascular model: proof of concept study from porcine experiments.

PubMed

Kamoi, Shun; Pretty, Christopher; Docherty, Paul; Squire, Dougie; Revie, James; Chiew, Yeong Shiong; Desaive, Thomas; Shaw, Geoffrey M; Chase, J Geoffrey

2014-01-01

Accurate, continuous, left ventricular stroke volume (SV) measurements can convey large amounts of information about patient hemodynamic status and response to therapy. However, direct measurements are highly invasive in clinical practice, and current procedures for estimating SV require specialized devices and significant approximation. This study investigates the accuracy of a three element Windkessel model combined with an aortic pressure waveform to estimate SV. Aortic pressure is separated into two components capturing; 1) resistance and compliance, 2) characteristic impedance. This separation provides model-element relationships enabling SV to be estimated while requiring only one of the three element values to be known or estimated. Beat-to-beat SV estimation was performed using population-representative optimal values for each model element. This method was validated using measured SV data from porcine experiments (N = 3 female Pietrain pigs, 29-37 kg) in which both ventricular volume and aortic pressure waveforms were measured simultaneously. The median difference between measured SV from left ventricle (LV) output and estimated SV was 0.6 ml with a 90% range (5th-95th percentile) -12.4 ml-14.3 ml. During periods when changes in SV were induced, cross correlations in between estimated and measured SV were above R = 0.65 for all cases. The method presented demonstrates that the magnitude and trends of SV can be accurately estimated from pressure waveforms alone, without the need for identification of complex physiological metrics where strength of correlations may vary significantly from patient to patient.

Heat transfer in porous medium embedded with vertical plate: Non-equilibrium approach - Part A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Badruddin, Irfan Anjum; Quadir, G. A.

2016-06-08

Heat transfer in a porous medium embedded with vertical flat plate is investigated by using thermal non-equilibrium model. Darcy model is employed to simulate the flow inside porous medium. It is assumed that the heat transfer takes place by natural convection and radiation. The vertical plate is maintained at isothermal temperature. The governing partial differential equations are converted into non-dimensional form and solved numerically using finite element method. Results are presented in terms of isotherms and streamlines for various parameters such as heat transfer coefficient parameter, thermal conductivity ratio, and radiation parameter.

Down-regulation of MIF by NFκB under hypoxia accelerated neuronal loss during stroke

PubMed Central

Zhang, Si; Zis, Odysseus; Ly, Philip T. T.; Wu, Yili; Zhang, Shuting; Zhang, Mingming; Cai, Fang; Bucala, Richard; Shyu, Woei-Cherng; Song, Weihong

2014-01-01

Neuronal apoptosis is one of the major causes of poststroke neurological deficits. Inflammation during the acute phase of stroke results in nuclear translocation of NFκB in affected cells in the infarct area. Macrophage migration inhibitory factor (MIF) promotes cardiomyocyte survival in mice following heart ischemia. However, the role of MIF during stroke remains limited. In this study, we showed that MIF expression is down-regulated by 0.75 ± 0.10-fold of the control in the infarct area in the mouse brains. Two functional cis-acing NFκB response elements were identified in the human MIF promoter. Dual activation of hypoxia and NFκB signaling resulted in significant reduction of MIF promoter activity to 0.86 ± 0.01-fold of the control. Furthermore, MIF reduced caspase-3 activation and protected neurons from oxidative stress- and in vitro ischemia/reperfusion-induced apoptosis. H2O2 significantly induced cell death with 12.81 ± 0.58-fold increase of TUNEL-positive cells, and overexpression of MIF blocked the H2O2-induced cell death. Disruption of the MIF gene in MIF-knockout mice resulted in caspase-3 activation, neuronal loss, and increased infarct development during stroke in vivo. The infarct volume was increased from 6.51 ± 0.74% in the wild-type mice to 9.07 ± 0.66% in the MIF-knockout mice. Our study demonstrates that MIF exerts a neuronal protective effect and that down-regulation of MIF by NFκB-mediated signaling under hypoxia accelerates neuronal loss during stroke. Our results suggest that MIF is an important molecule for preserving a longer time window for stroke treatment, and strategies to maintain MIF expression at physiological level could have beneficial effects for stroke patients.—Zhang, S., Zis, O., Ly, P. T. T., Wu, Y., Zhang, S., Zhang, M., Cai, F., Bucala, R., Shyu, W.-C., Song, W. Down-regulation of MIF by NFκB under hypoxia accelerated neuronal loss during stroke. PMID:24970391

FUEL ELEMENT INTERLOCKING ARRANGEMENT

DOEpatents

Fortescue, P.; Nicoll, D.

1963-01-01

This patent relates to a system for mutually interlocking a multiplicity of elongated, parallel, coextensive, upright reactor fuel elements so as to render a laterally selfsupporting bundle, while admitting of concurrent, selective, vertical withdrawal of a sizeable number of elements without any of the remaining elements toppling, Each element is provided with a generally rectangular end cap. When a rank of caps is aligned in square contact, each free edge centrally defines an outwardly profecting dovetail, and extremitally cooperates with its adjacent cap by defining a juxtaposed half of a dovetail- receptive mortise. Successive ranks are staggered to afford mating of their dovetails and mortises. (AEC)

A seismic analysis for masonry constructions: The different schematization methods of masonry walls

NASA Astrophysics Data System (ADS)

Olivito, Renato. S.; Codispoti, Rosamaria; Scuro, Carmelo

2017-11-01

Seismic analysis of masonry structures is usually analyzed through the use of structural calculation software based on equivalent frames method or to macro-elements method. In these approaches, the masonry walls are divided into vertical elements, masonry walls, and horizontal elements, so-called spandrel elements, interconnected by rigid nodes. The aim of this work is to make a critical comparison between different schematization methods of masonry wall underlining the structural importance of the spandrel elements. In order to implement the methods, two different structural calculation software were used and an existing masonry building has been examined.

A molded surface-micromachining and bulk etching release (MOSBE) fabrication platform on (1 1 1) Si for MOEMS

NASA Astrophysics Data System (ADS)

Wu, Mingching; Fang, Weileun

2006-02-01

This work attempts to integrate poly-Si thin film and single-crystal-silicon (SCS) structures in a monolithic process. The process integrated multi-depth DRIE (deep reactive ion etching), trench-refilled molding, a two poly-Si MUMPs process and (1 1 1) Si bulk micromachining to accomplish multi-thickness and multi-depth structures for superior micro-optical devices. In application, a SCS scanning mirror driven by self-aligned vertical comb-drive actuators was demonstrated. The stiffness of the mirror was significantly increased by thick SCS structures. The thin poly-Si film served as flexible torsional springs and electrical routings. The depth difference of the vertical comb electrodes was tuned by DRIE to increase the devices' stroke. Finally, a large moving space was available after the bulk Si etching. In summary, the present fabrication process, named (1 1 1) MOSBE (molded surface-micromachining and bulk etching release on (1 1 1) Si substrate), can further integrate with the MUMPs devices to establish a more powerful platform.

A Physics Based Vehicle Terrain Interaction Model for Soft Soil off-Road Vehicle Simulations

DTIC Science & Technology

2012-01-01

assumed terrain deformation, use of empirical relationships for the deformation, or finite/discrete element approaches for the terrain. A real-time...vertical columns of soil, and the deformation of each is modeled using visco-elasto-plastic compressibility relationships that relate subsoil pressures to...produced by tractive and turning forces will also be incorporated into the model. Both the vertical and horizontal force/displacement relationships

Explicit Nonlinear Finite Element Geometric Analysis of Parabolic Leaf Springs under Various Loads

PubMed Central

Kong, Y. S.; Omar, M. Z.; Chua, L. B.; Abdullah, S.

2013-01-01

This study describes the effects of bounce, brake, and roll behavior of a bus toward its leaf spring suspension systems. Parabolic leaf springs are designed based on vertical deflection and stress; however, loads are practically derived from various modes especially under harsh road drives or emergency braking. Parabolic leaf springs must sustain these loads without failing to ensure bus and passenger safety. In this study, the explicit nonlinear dynamic finite element (FE) method is implemented because of the complexity of experimental testing A series of load cases; namely, vertical push, wind-up, and suspension roll are introduced for the simulations. The vertical stiffness of the parabolic leaf springs is related to the vehicle load-carrying capability, whereas the wind-up stiffness is associated with vehicle braking. The roll stiffness of the parabolic leaf springs is correlated with the vehicle roll stability. To obtain a better bus performance, two new parabolic leaf spring designs are proposed and simulated. The stress level during the loadings is observed and compared with its design limit. Results indicate that the newly designed high vertical stiffness parabolic spring provides the bus a greater roll stability and a lower stress value compared with the original design. Bus safety and stability is promoted, as well as the load carrying capability. PMID:24298209

Explicit nonlinear finite element geometric analysis of parabolic leaf springs under various loads.

PubMed

Kong, Y S; Omar, M Z; Chua, L B; Abdullah, S

2013-01-01

This study describes the effects of bounce, brake, and roll behavior of a bus toward its leaf spring suspension systems. Parabolic leaf springs are designed based on vertical deflection and stress; however, loads are practically derived from various modes especially under harsh road drives or emergency braking. Parabolic leaf springs must sustain these loads without failing to ensure bus and passenger safety. In this study, the explicit nonlinear dynamic finite element (FE) method is implemented because of the complexity of experimental testing A series of load cases; namely, vertical push, wind-up, and suspension roll are introduced for the simulations. The vertical stiffness of the parabolic leaf springs is related to the vehicle load-carrying capability, whereas the wind-up stiffness is associated with vehicle braking. The roll stiffness of the parabolic leaf springs is correlated with the vehicle roll stability. To obtain a better bus performance, two new parabolic leaf spring designs are proposed and simulated. The stress level during the loadings is observed and compared with its design limit. Results indicate that the newly designed high vertical stiffness parabolic spring provides the bus a greater roll stability and a lower stress value compared with the original design. Bus safety and stability is promoted, as well as the load carrying capability.

Human body modeling method to simulate the biodynamic characteristics of spine in vivo with different sitting postures.

PubMed

Dong, Rui-Chun; Guo, Li-Xin

2017-11-01

The aim of this study is to model the computational model of seated whole human body including skeleton, muscle, viscera, ligament, intervertebral disc, and skin to predict effect of the factors (sitting postures, muscle and skin, buttocks, viscera, arms, gravity, and boundary conditions) on the biodynamic characteristics of spine. Two finite element models of seated whole body and a large number of finite element models of different ligamentous motion segments were developed and validated. Static, modal, and transient dynamic analyses were performed. The predicted vertical resonant frequency of seated body model was in the range of vertical natural frequency of 4 to 7 Hz. Muscle, buttocks, viscera, and the boundary conditions of buttocks have influence on the vertical resonant frequency of spine. Muscle played a very important role in biodynamic response of spine. Compared with the vertical posture, the posture of lean forward or backward led to an increase in stress on anterior or lateral posterior of lumbar intervertebral discs. This indicated that keeping correct posture could reduce the injury of vibration on lumbar intervertebral disc under whole-body vibration. The driving posture not only reduced the load of spine but also increased the resonant frequency of spine. Copyright © 2017 John Wiley & Sons, Ltd.

An ischemic stroke patient with free floating thrombus in carotid artery, successfully treated by open carotid thrombectomy: a first case report in Nepal.

PubMed

Shrestha, Prabin; Adhikari, Rupendra; Tamrakar, Samantha; Pant, Basanta; Koirala, Bhagwan; Yamaguchi, Satoshi; Kurisu, Kaoru

2012-12-01

Free floating thrombus in the carotid artery is a well-known phenomenon, though relatively rare. We present a case in which we performed open surgery and achieved successful retrieval of the thrombus. A 40 year-old male patient presented with ischemic stroke and mild left hemiparesis. Computerized tomography and magnetic resonance imaging showed infarction in the right parieto-occipital area. Carotid Doppler study showed carotid stenosis on the right side. Further investigation with CT angiography of the neck vessels confirmed significant carotid artery occlusion with a free-floating thrombus in the internal carotid artery. Carotid endarterectomy was planned under EEG monitoring. The right carotid artery was exposed with a vertical incision along the medial margin of the sternocleido-mastoid muscle. The carotid artery was opened and, as expected, showed a soft, mobile thrombus. Thus thrombectomy was planned. A 2 Fr fogarty catheter was introduced distal to the thrombus, the balloon was inflated and pulled back gently, which removed the thrombus completely. There was no postoperative complication and the patient is fine at 1 year follow-up.

Coordination of multiple appendages in drag-based swimming.

PubMed

Alben, Silas; Spears, Kevin; Garth, Stephen; Murphy, David; Yen, Jeannette

2010-11-06

Krill are aquatic crustaceans that engage in long distance migrations, either vertically in the water column or horizontally for 10 km (over 200,000 body lengths) per day. Hence efficient locomotory performance is crucial for their survival. We study the swimming kinematics of krill using a combination of experiment and analysis. We quantify the propulsor kinematics for tethered and freely swimming krill in experiments, and find kinematics that are very nearly metachronal. We then formulate a drag coefficient model which compares metachronal, synchronous and intermediate motions for a freely swimming body with two legs. With fixed leg velocity amplitude, metachronal kinematics give the highest average body speed for both linear and quadratic drag laws. The same result holds for five legs with the quadratic drag law. When metachronal kinematics is perturbed towards synchronous kinematics, an analysis shows that the velocity increase on the power stroke is outweighed by the velocity decrease on the recovery stroke. With fixed time-averaged work done by the legs, metachronal kinematics again gives the highest average body speed, although the advantage over synchronous kinematics is reduced.

Functional Response of NiTi Elements for Smart Micro-actuation Applications

NASA Astrophysics Data System (ADS)

Biffi, C. A.; Nespoli, A.; Previtali, B.; Villa, E.; Tuissi, A.

2014-07-01

Shape memory alloys (SMAs) can be considered a good candidate for actuation applications in the current micro-technology field. In the micro-scale, the temporal response of the SMA actuators can be improved, because of faster cooling during the austenite-martensite transformation. One of the most investigated geometries for this purpose has been the snake-like arrangement, which allows high strokes with considerable forces to be obtained. In this work, SMA elements for micro-actuators were patterned by laser machining in a snake-like shape. Subsequent surface chemical etching was adopted to improve the functional properties of the micro-elements. Calorimetric analysis and thermo-mechanical response of 90 μm thick SMA elements were reported for the evaluation of their functional performances. Moreover, the effect of post-thermal treatment and grain orientation were also evaluated on the final performances.

Modelling element distributions in the atmospheres of magnetic Ap stars

NASA Astrophysics Data System (ADS)

Alecian, G.; Stift, M. J.

2007-11-01

Context: In recent papers convincing evidence has been presented for chemical stratification in Ap star atmospheres, and surface abundance maps have been shown to correlate with the magnetic field direction. Radiatively driven diffusion, which is known to be sensitive to the magnetic field strength and direction, is among the processes responsible for these inhomogeneities. Aims: Here we explore the hypothesis that equilibrium stratifications - such that the diffusive particle flux is close to zero throughout the atmosphere - can, in a number of cases, explain the observed abundance maps and vertical distributions of the various elements. Methods: An iterative scheme adjusts the abundances in such a way as to achieve either zero particle flux or zero effective acceleration throughout the atmosphere, taking strength and direction of the magnetic field into account. Results: The investigation of equilibrium stratifications in stellar atmospheres with temperatures from 8500 to 12 000 K and fields up to 10 kG reveals considerable variations in the vertical distribution of the 5 elements studied (Mg, Si, Ca, Ti, Fe), often with zones of large over- or under-abundances and with indications of other competing processes (such as mass loss). Horizontal magnetic fields can be very efficient in helping the accumulation of elements in higher layers. Conclusions: A comparison between our calculations and the vertical abundance profiles and surface maps derived by magnetic Doppler imaging reveals that equilibrium stratifications are in a number of cases consistent with the main trends inferred from observed spectra. However, it is not clear whether such equilibrium solutions will ever be reached during the evolution of an Ap star.

A New Concept in Helicopter Communications Antennas

NASA Technical Reports Server (NTRS)

Pogorzelski, R. J.

1995-01-01

We consider a five blade rotor and envision an array with one element mounted on each rotor blade. These elements may be dipoles or horizontal slots depending upon the desired polarization characteristics. For example, slots would provide vertical polarization on horizontal paths. The array is excited through a novel type of rotary joint located on the rotor shaft.

Application of Classical Land Surveying Measurement Methods for Determining the Vertical Displacement of Railway Bridges

NASA Astrophysics Data System (ADS)

Gawronek, Pelagia; Makuch, Maria

2017-12-01

The classical measurements of stability of railway bridge, in the context of determining the vertical displacements of the object, consisted on precise leveling of girders and trigonometric leveling of controlled points (fixed into girders' surface). The construction elements, which were measured in two ways, in real terms belonged to the same vertical planes. Altitude measurements of construction were carried out during periodic structural stability tests and during static load tests of bridge by train. The specificity of displacement measurements, the type of measured object and the rail land surveying measurement conditions were determinants to define methodology of altitude measurement. The article presents compatibility of vertical displacements of steel railway bridge, which were developed in two measurement methods. In conclusion, the authors proposed the optimum concept of determining the vertical displacements of girders by using precise and trigonometric leveling (in terms of accuracy, safety and economy of measurement).

Does a foot-drop implant improve kinetic and kinematic parameters in the foot and ankle?

PubMed

Daniilidis, Kiriakos; Jakubowitz, Eike; Thomann, Anna; Ettinger, Sarah; Stukenborg-Colsman, Christina; Yao, Daiwei

2017-04-01

Unlike the drop foot therapy with ortheses, the therapeutic effect of an implantable peroneus nerve stimulator (iPNS) is not well described. IPNS is a dynamic therapy option which is placed directly to the motoric part of the peroneal nerve and evokes a dorsiflexion of the paralysed foot. This retrospective study evaluates the kinematics and kinetics in drop foot patients who were treated with an iPNS. 18 subjects (mean age 51.3 years) with a chronic stroke-related drop foot were treated with an implantable peroneal nerve stimulator. After a mean follow-up from 12.5 months, kinematics and kinetics as well as spatiotemporal parameters were evaluated and compared in activated and deactivated iPNS. Therefore, a gait analysis with motion capture system (Vicon Motion System Ltd®, Oxford, UK) and Plug-in-Gait model was performed. The study showed significantly improved results in ankle dorsiflexion from 6.8° to 1.8° at the initial contact and from -7.3° to 0.9° during swing phase (p ≤ 0.004 and p ≤ 0.005, respectively). Likewise, we could measure improved kinetics, i.a. with a statistically significant improvement in vertical ground reaction force at loading response from 99.76 to 106.71 N/kg (p = 0.043). Enhanced spatiotemporal results in cadence, douple support, stride length, and walking speed could also be achieved, but without statistical significance (p > 0.05). The results show statistically significant improvement in ankle dorsiflexion and vertical ground reaction forces. These facts indicate a more gait stability and gait efficacy. Therefore, the use of an iPNS appears an encouraging therapeutic option for patients with a stroke-related drop foot.

Differences in kinematics and energy cost between front crawl and backstroke below the anaerobic threshold.

PubMed

Gonjo, Tomohiro; McCabe, Carla; Sousa, Ana; Ribeiro, João; Fernandes, Ricardo J; Vilas-Boas, João Paulo; Sanders, Ross

2018-06-01

The purpose of this study was to determine kinematic and energetic differences between front crawl and backstroke performed at the same aerobic speeds. Ten male competitive swimmers performed front crawl and backstroke at a pre-determined sub-anaerobic threshold speed to assess energy cost (through oxygen uptake measurement) and kinematics (using three-dimensional videography to determine stroke frequency and length, intra-cycle velocity fluctuation, three-dimensional wrist and ankle speeds, and vertical and lateral ankle range of motion). For detailed kinematic analysis, resultant displacement, the duration, and three-dimensional speed of the wrist during the entry, pull, push, and release phases were also investigated. There were no differences in stroke frequency/length and intra-cycle velocity fluctuation between the swimming techniques, however, swimmers had lower energy cost in front crawl than in backstroke (0.77 ± 0.08 vs 0.91 ± 0.12 kJ m -1 , p < 0.01). Slower three-dimensional wrist and ankle speeds under the water (1.29 ± 0.10 vs 1.55 ± 0.10 and 0.80 ± 0.16 vs 0.97 ± 0.13 m s -1 , both p < 0.01) and smaller ankle vertical range of motion (0.36 ± 0.06 vs 0.47 ± 0.07 m, p < 0.01) in front crawl than in backstroke were also observed, which indirectly suggested higher propulsive efficiency in front crawl. Front crawl is less costly than backstroke, and limbs motion in front crawl is more effective than in backstroke.

Dynamically adjustable foot-ground contact model to estimate ground reaction force during walking and running.

PubMed

Jung, Yihwan; Jung, Moonki; Ryu, Jiseon; Yoon, Sukhoon; Park, Sang-Kyoon; Koo, Seungbum

2016-03-01

Human dynamic models have been used to estimate joint kinetics during various activities. Kinetics estimation is in demand in sports and clinical applications where data on external forces, such as the ground reaction force (GRF), are not available. The purpose of this study was to estimate the GRF during gait by utilizing distance- and velocity-dependent force models between the foot and ground in an inverse-dynamics-based optimization. Ten males were tested as they walked at four different speeds on a force plate-embedded treadmill system. The full-GRF model whose foot-ground reaction elements were dynamically adjusted according to vertical displacement and anterior-posterior speed between the foot and ground was implemented in a full-body skeletal model. The model estimated the vertical and shear forces of the GRF from body kinematics. The shear-GRF model with dynamically adjustable shear reaction elements according to the input vertical force was also implemented in the foot of a full-body skeletal model. Shear forces of the GRF were estimated from body kinematics, vertical GRF, and center of pressure. The estimated full GRF had the lowest root mean square (RMS) errors at the slow walking speed (1.0m/s) with 4.2, 1.3, and 5.7% BW for anterior-posterior, medial-lateral, and vertical forces, respectively. The estimated shear forces were not significantly different between the full-GRF and shear-GRF models, but the RMS errors of the estimated knee joint kinetics were significantly lower for the shear-GRF model. Providing COP and vertical GRF with sensors, such as an insole-type pressure mat, can help estimate shear forces of the GRF and increase accuracy for estimation of joint kinetics. Copyright © 2016 Elsevier B.V. All rights reserved.

Viewing medium affects arm motor performance in 3D virtual environments.

PubMed

Subramanian, Sandeep K; Levin, Mindy F

2011-06-30

2D and 3D virtual reality platforms are used for designing individualized training environments for post-stroke rehabilitation. Virtual environments (VEs) are viewed using media like head mounted displays (HMDs) and large screen projection systems (SPS) which can influence the quality of perception of the environment. We estimated if there were differences in arm pointing kinematics when subjects with and without stroke viewed a 3D VE through two different media: HMD and SPS. Two groups of subjects participated (healthy control, n=10, aged 53.6 ± 17.2 yrs; stroke, n=20, 66.2 ± 11.3 yrs). Arm motor impairment and spasticity were assessed in the stroke group which was divided into mild (n=10) and moderate-to-severe (n=10) sub-groups based on Fugl-Meyer Scores. Subjects pointed (8 times each) to 6 randomly presented targets located at two heights in the ipsilateral, middle and contralateral arm workspaces. Movements were repeated in the same VE viewed using HMD (Kaiser XL50) and SPS. Movement kinematics were recorded using an Optotrak system (Certus, 6 markers, 100 Hz). Upper limb motor performance (precision, velocity, trajectory straightness) and movement pattern (elbow, shoulder ranges and trunk displacement) outcomes were analyzed using repeated measures ANOVAs. For all groups, there were no differences in endpoint trajectory straightness, shoulder flexion and shoulder horizontal adduction ranges and sagittal trunk displacement between the two media. All subjects, however, made larger errors in the vertical direction using HMD compared to SPS. Healthy subjects also made larger errors in the sagittal direction, slower movements overall and used less range of elbow extension for the lower central target using HMD compared to SPS. The mild and moderate-to-severe sub-groups made larger RMS errors with HMD. The only advantage of using the HMD was that movements were 22% faster in the moderate-to-severe stroke sub-group compared to the SPS. Despite the similarity in majority of the movement kinematics, differences in movement speed and larger errors were observed for movements using the HMD. Use of the SPS may be a more comfortable and effective option to view VEs for upper limb rehabilitation post-stroke. This has implications for the use of VR applications to enhance upper limb recovery. © 2011 Subramanian and Levin; licensee BioMed Central Ltd.

Viewing medium affects arm motor performance in 3D virtual environments

PubMed Central

2011-01-01

Background 2D and 3D virtual reality platforms are used for designing individualized training environments for post-stroke rehabilitation. Virtual environments (VEs) are viewed using media like head mounted displays (HMDs) and large screen projection systems (SPS) which can influence the quality of perception of the environment. We estimated if there were differences in arm pointing kinematics when subjects with and without stroke viewed a 3D VE through two different media: HMD and SPS. Methods Two groups of subjects participated (healthy control, n = 10, aged 53.6 ± 17.2 yrs; stroke, n = 20, 66.2 ± 11.3 yrs). Arm motor impairment and spasticity were assessed in the stroke group which was divided into mild (n = 10) and moderate-to-severe (n = 10) sub-groups based on Fugl-Meyer Scores. Subjects pointed (8 times each) to 6 randomly presented targets located at two heights in the ipsilateral, middle and contralateral arm workspaces. Movements were repeated in the same VE viewed using HMD (Kaiser XL50) and SPS. Movement kinematics were recorded using an Optotrak system (Certus, 6 markers, 100 Hz). Upper limb motor performance (precision, velocity, trajectory straightness) and movement pattern (elbow, shoulder ranges and trunk displacement) outcomes were analyzed using repeated measures ANOVAs. Results For all groups, there were no differences in endpoint trajectory straightness, shoulder flexion and shoulder horizontal adduction ranges and sagittal trunk displacement between the two media. All subjects, however, made larger errors in the vertical direction using HMD compared to SPS. Healthy subjects also made larger errors in the sagittal direction, slower movements overall and used less range of elbow extension for the lower central target using HMD compared to SPS. The mild and moderate-to-severe sub-groups made larger RMS errors with HMD. The only advantage of using the HMD was that movements were 22% faster in the moderate-to-severe stroke sub-group compared to the SPS. Conclusions Despite the similarity in majority of the movement kinematics, differences in movement speed and larger errors were observed for movements using the HMD. Use of the SPS may be a more comfortable and effective option to view VEs for upper limb rehabilitation post-stroke. This has implications for the use of VR applications to enhance upper limb recovery. PMID:21718542

Simulation of rotor blade element turbulence

NASA Technical Reports Server (NTRS)

Mcfarland, R. E.; Duisenberg, Ken

1995-01-01

A piloted, motion-based simulation of Sikorsky's Black Hawk helicopter was used as a platform for the investigation of rotorcraft responses to vertical turbulence. By using an innovative temporal and geometrical distribution algorithm that preserved the statistical characteristics of the turbulence over the rotor disc, stochastic velocity components were applied at each of twenty blade-element stations. This model was implemented on NASA Ames' Vertical Motion Simulator (VMS), and ten test pilots were used to establish that the model created realistic cues. The objectives of this research included the establishment of a simulation-technology basis for future investigation into real-time turbulence modeling. This goal was achieved; our extensive additions to the rotor model added less than a 10 percent computational overhead. Using a VAX 9000 computer the entire simulation required a cycle time of less than 12 msec. Pilot opinion during this simulation was generally quite favorable. For low speed flight the consensus was that SORBET (acronym for title) was better than the conventional body-fixed model, which was used for comparison purposes, and was determined to be too violent (like a washboard). For high speed flight the pilots could not identify differences between these models. These opinions were something of a surprise because only the vertical turbulence component on the rotor system was implemented in SORBET. Because of the finite-element distribution of the inputs, induced outputs were observed in all translational and rotational axes. Extensive post-simulation spectral analyses of the SORBET model suggest that proper rotorcraft turbulence modeling requires that vertical atmospheric disturbances not be superimposed at the vehicle center of gravity but, rather, be input into the rotor system, where the rotor-to-body transfer function severely attenuates high frequency rotorcraft responses.

Contactor/filter improvements

DOEpatents

Stelman, David

1989-01-01

A contactor/filter arrangement for removing particulate contaminants from a gaseous stream includes a housing having a substantially vertically oriented granular material retention member with upstream and downstream faces, a substantially vertically oriented microporous gas filter element, wherein the retention member and the filter element are spaced apart to provide a zone for the passage of granular material therethrough. The housing further includes a gas inlet means, a gas outlet means, and means for moving a body of granular material through the zone. A gaseous stream containing particulate contaminants passes through the gas inlet means as well as through the upstream face of the granular material retention member, passing through the retention member, the body of granular material, the microporous gas filter element, exiting out of the gas outlet means. Disposed on the upstream face of the filter element is a cover screen which isolates the filter element from contact with the moving granular bed and collects a portion of the particulates so as to form a dust cake having openings small enough to exclude the granular material, yet large enough to receive the dust particles. In one embodiment, the granular material is comprised of prous alumina impregnated with CuO, with the cover screen cleaned by the action of the moving granular material as well as by backflow pressure pulses.

Static Buckling Model Tests and Elasto-plastic Finite Element Analysis of a Pile in Layers with Various Thicknesses

NASA Astrophysics Data System (ADS)

Okajima, Kenji; Imai, Junichi; Tanaka, Tadatsugu; Iida, Toshiaki

Damage to piles in the liquefied ground is frequently reported. Buckling by the excess vertical load could be one of the causes of the pile damage, as well as the lateral flow of the ground and the lateral load at the pile head. The buckling mechanism is described as a complicated interaction between the pile deformation by the vertical load and the earth pressure change cased by the pile deformation. In this study, series of static buckling model tests of a pile were carried out in dried sand ground with various thickness of the layer. Finite element analysis was applied to the test results to verify the effectiveness of the elasto-plastic finite element analysis combining the implicit-explicit mixed type dynamic relaxation method with the return mapping method to the pile buckling problems. The test results and the analysis indicated the possibility that the buckling load of a pile decreases greatly where the thickness of the layer increases.

Crash Simulation of a Vertical Drop Test of a Commuter-Class Aircraft

NASA Technical Reports Server (NTRS)

Jackson, Karen E.; Fasanella, Edwin L.

2004-01-01

A finite element model of an ATR42-300 commuter-class aircraft was developed and a crash simulation was executed. Analytical predictions were correlated with data obtained from a 30-ft/s (9.14-m/s) vertical drop test of the aircraft. The purpose of the test was to evaluate the structural response of the aircraft when subjected to a severe, but survivable, impact. The aircraft was configured with seats, dummies, luggage, and other ballast. The wings were filled with 8,700 lb. (3,946 kg) of water to represent the fuel. The finite element model, which consisted of 57,643 nodes and 62,979 elements, was developed from direct measurements of the airframe geometry. The seats, dummies, luggage, fuel, and other ballast were represented using concentrated masses. The model was executed in LS-DYNA, a commercial code for performing explicit transient dynamic simulations. Predictions of structural deformation and selected time-history responses were generated. The simulation was successfully validated through extensive test-analysis correlation.

Crash Simulation of a Boeing 737 Fuselage Section Vertical Drop Test

NASA Technical Reports Server (NTRS)

Fasanella, Edwin L.; Jackson, Karen E.; Jones, Yvonne T.; Frings, Gary; Vu, Tong

2004-01-01

A 30-ft/s vertical drop test of a fuselage section of a Boeing 737 aircraft was conducted in October of 1999 at the FAA Technical Center in Atlantic City, NJ. This test was performed to evaluate the structural integrity of a conformable auxiliary fuel tank mounted beneath the floor and to determine its effect on the impact response of the airframe structure and the occupants. The test data were used to compare with a finite element simulation of the fuselage structure and to gain a better understanding of the impact physics through analytical/experimental correlation. To perform this simulation, a full-scale 3-dimensional finite element model of the fuselage section was developed using the explicit, nonlinear transient-dynamic finite element code, MSC.Dytran. The emphasis of the simulation was to predict the structural deformation and floor-level acceleration responses obtained from the drop test of the B737 fuselage section with the auxiliary fuel tank.

[Landscape quality evaluation and vertical structure optimization of natural broadleaf forest].

PubMed

Ouyang, Xun-zhi; Liao, Wei-ming; Peng, Shi-kui

2007-06-01

Taking the natural broadleaf forest in Wuyuan County of Jiangxi Province as study object, a total of 30 representative photos of near-view landscapes and related information were collected. The scenic beauty values were acquired by public judgment method, and the relationship models of scenic beauty values and landscape elements were established by using multiple mathematical model. The results showed that the main elements affecting the near-view landscape quality of natural broadleaf forest were the trunk form, stand density, undergrowth coverage and height, natural pruning, and color richness, with the partial correlation coefficients being 0.4482-0.7724, which were significant or very significant by t-test. The multiple correlation coefficient of the model reached 0.9508, showing very significant by F test (F = 36.11). Straight trunk, better natural pruning and rich color did well, while the super-high or low stand density and undergrowth coverage and height did harm to the scenic beauty. Several management measures for the vertical structure optimization of these landscape elements were put forward.

Training using a new multidirectional reach tool improves balance in individuals with stroke.

PubMed

Khumsapsiri, Numpung; Siriphorn, Akkradate; Pooranawatthanakul, Kanokporn; Oungphalachai, Tanyarut

2018-04-01

Previous studies suggested that limits of stability (LOS) training with visual feedback using commercial equipment could be used to improve balance ability in individuals with stroke. However, this system is expensive. In this study, we created a new tool from inexpensive elements based on LOS training using visual feedback. The aim of this study was to investigate the effect of training using a new multidirectional reach tool on balance in individuals with stroke. A single-blind randomized control trial was conducted. Individuals with stroke (n = 16; age range 38-72 years) were recruited. Participants in the experimental group were trained with the multidirectional reach training for 30 min and conventional physical therapy for 30 min per day, 3 days a week for 4 weeks. Participants in the control group received conventional physical therapy for 30 min per day, 3 days a week for 4 weeks. The outcomes were LOS, weight-bearing squat, and Fullerton Advanced Balance scale. All of the outcome measures were measured at pretraining, post-training, and 1 month follow-up. At post-training and 1-month follow-up, the participants in the experimental group had an improvement of dynamic balance than the control group. Furthermore, the activity assessment by Fullerton Advanced Balance scale was more improved at 1 month follow-up in the experimental group than control group. The results of this study provide evidence that training using a new multidirectional reach tool is effective for improving balance in individuals with stroke. Copyright © 2018 John Wiley & Sons, Ltd.

The hidden life of integrative and conjugative elements

PubMed Central

Delavat, François; Miyazaki, Ryo; Carraro, Nicolas; Pradervand, Nicolas

2017-01-01

Abstract Integrative and conjugative elements (ICEs) are widespread mobile DNA that transmit both vertically, in a host-integrated state, and horizontally, through excision and transfer to new recipients. Different families of ICEs have been discovered with more or less restricted host ranges, which operate by similar mechanisms but differ in regulatory networks, evolutionary origin and the types of variable genes they contribute to the host. Based on reviewing recent experimental data, we propose a general model of ICE life style that explains the transition between vertical and horizontal transmission as a result of a bistable decision in the ICE–host partnership. In the large majority of cells, the ICE remains silent and integrated, but hidden at low to very low frequencies in the population specialized host cells appear in which the ICE starts its process of horizontal transmission. This bistable process leads to host cell differentiation, ICE excision and transfer, when suitable recipients are present. The ratio of ICE bistability (i.e. ratio of horizontal to vertical transmission) is the outcome of a balance between fitness costs imposed by the ICE horizontal transmission process on the host cell, and selection for ICE distribution (i.e. ICE ‘fitness’). From this emerges a picture of ICEs as elements that have adapted to a mostly confined life style within their host, but with a very effective and dynamic transfer from a subpopulation of dedicated cells. PMID:28369623

Why Pteropods Flap Their Wings, Periodically Pitch Their Shell, and Swim in a Sawtooth-like Trajectory

NASA Astrophysics Data System (ADS)

Adhikari, D.; Webster, D. R.; Yen, J.

2016-02-01

Antarctic pteropods (Limacina helicina antarctica), which are currently threatened by ocean acidification, swim in seawater with a pair of gelatinous parapodia (or "wings") via a distinctive propulsion mechanism. By flapping their parapodia in a way that resembles insect flight, they exhibit a unique shell wobble (or periodic shell pitching) motion and sawtooth-like trajectory. We present three-dimensional kinematics and volumetric fluid velocity fields for upward-swimming pteropods. Time-resolved data were collected with a unique infrared tomographic particle image velocimetry (tomo-PIV) system that was transported to Palmer Station, Antarctica. Both power and recovery strokes of the parapodia propel the pteropod (1.5 - 5 mm in size) upward in a sawtooth-like trajectory with average speed of 14 - 30 mm/s and periodically pitch the shell at 1.9 - 3 Hz with up to 110° difference in pitching angle. The pitch motion effectively positions the parapodia such that they stroke downward during both the power and recovery strokes. We use the kinematics measurement to illustrate the relationship between flapping, swimming and pitching, where the corresponding Reynolds numbers (i.e. Ref, ReU, and ReΩ) characterize the motion of the pteropod. For example, when Ref < 50, the shell does not pitch and the pteropod swims abnormally with little or no vertical translation. We show that the flow field and vortices generated during pteropod propulsion resemble some aspects of insect-flight aerodynamics reported in classic literature, albeit with distinct aquatic variations.

Three-Dimensional Shallow Water Adaptive Hydraulics (ADH-SW3) Validation: Galveston Bay Hydrodynamics and Salinity Transport

DTIC Science & Technology

2015-04-01

model mesh with elements (vertical co-ordinate in meters). ....................... 5 Figure 3. Ocean tidal boundary (Hour 0 = 1 Jan 1990, 12:00 a.m...7 Figure 4. Ocean salt boundary (Hour 0 = 1 Jan 1990, 12:00 a.m...channel and the connections of Galveston Bay to the open ocean . Figures 1 and 2 illustrate the distribution of vertical layers and resolution in the

Application of Statistical Learning Theory to Plankton Image Analysis

DTIC Science & Technology

2006-06-01

linear distance interval from 1 to 40 pixels and two directions formula (horizontal & vertical, and diagonals), EF2 is EF with 7 ex- ponential distance...and four directions formula (horizontal, vertical and two diagonals). It is clear that exponential distance inter- val works better than the linear ...PSI - PS by Vincent, linear and pseudo opening and closing spectra, each has 40 elements, total feature length of 160. PS2 - PS modified from Mei- jster

Ultra-Low Threshold Vertical-Cavity Surface-Emitting Lasers for USAF Applications

DTIC Science & Technology

2005-01-01

molecular beam epitaxy , semiconductors, finite element method, modeling and simulation, oxidation furnace 16. SECURITY CLASSIFICATION OF: 19a. NAME OF...Patterson Air Force Base). Device material growth was accomplished by means of molecular beam epitaxy (MBE) using a Varian GENII MBE system owned by the...grown by molecular beam epitaxy on a GaAs substrate. Vertical posts, with square and circular cross sections ranging in size from 5 to 40 microns

Vortex Generators to Control Boundary Layer Interactions

NASA Technical Reports Server (NTRS)

Babinsky, Holger (Inventor); Loth, Eric (Inventor); Lee, Sang (Inventor)

2014-01-01

Devices for generating streamwise vorticity in a boundary includes various forms of vortex generators. One form of a split-ramp vortex generator includes a first ramp element and a second ramp element with front ends and back ends, ramp surfaces extending between the front ends and the back ends, and vertical surfaces extending between the front ends and the back ends adjacent the ramp surfaces. A flow channel is between the first ramp element and the second ramp element. The back ends of the ramp elements have a height greater than a height of the front ends, and the front ends of the ramp elements have a width greater than a width of the back ends.

Reading the Multimodal "Ologies": New Literacy Challenges or Old Wine in New Bottles?

ERIC Educational Resources Information Center

Williams, Sandra

2015-01-01

In this article, the "Ologies" series of books are interrogated with a focus on whether they present new challenges for the reader or merely require previously acquired skills. The multimodal texts are unusual in that they combine non-fiction with fantasy while including tactile elements such as flaps, pull-outs and items to stroke. Ways…

Effects of soil type on leaching and runoff transport of rare earth elements and phosphorous in laboratory experiments.

PubMed

Wang, Lingqing; Liang, Tao; Chong, Zhongyi; Zhang, Chaosheng

2011-01-01

Through leaching experiments and simulated rainfall experiments, characteristics of vertical leaching of exogenous rare earth elements (REEs) and phosphorus (P) and their losses with surface runoff during simulated rainfall in different types of soils (terra nera soil, cinnamon soil, red soil, loess soil, and purple soil) were investigated. Results of the leaching experiments showed that vertical transports of REEs and P were relatively low, with transport depths less than 6 cm. The vertical leaching rates of REEs and P in the different soils followed the order of purple soil > terra nera soil > red soil > cinnamon soil > loess soil. Results of the simulated rainfall experiments (83 mm h⁻¹) revealed that more than 92% of REEs and P transported with soil particles in runoff. The loss rates of REEs and P in surface runoff in the different soil types were in the order of loess soil > terra nera soil > cinnamon soil > red soil > purple soil. The total amounts of losses of REEs and P in runoff were significantly correlated.

Interaction of an Artificially Thickened Boundary Layer with a Vertically Mounted Pitching Airfoil

NASA Astrophysics Data System (ADS)

Hohman, Tristen; Smits, Alexander; Martinelli, Luigi

2011-11-01

Wind energy represents a large portion of the growing market in alternative energy technologies and the current landscape has been dominated by the more prevalent horizontal axis wind turbine. However, there are several advantages to the vertical axis wind turbine (VAWT) or Darrieus type design and yet there is much to be understood about how the atmospheric boundary layer (ABL) affects their performance. In this study the ABL was simulated in a wind tunnel through the use of elliptical shaped vortex generators, a castellated wall, and floor roughness elements as described in the method of Counihan (1967) and then verified its validity by hot wire measurement of the mean velocity profile as well as the turbulence intensity. The motion of an blade element around a vertical axis is approximated through the use of a pitching airfoil. The wake of the airfoil is investigated through hot wire anemometry in both uniform flow and in the simulated boundary layer both at Re = 1 . 37 ×105 based on the chord of the airfoil. Sponsored by Hopewell Wind Power (Hong Kong) Limited.

Effect of triangular element orientation on finite element solutions of the Helmholtz equation

NASA Technical Reports Server (NTRS)

Baumeister, K. J.

1986-01-01

The Galerkin finite element solutions for the scalar homogeneous Helmholtz equation are presented for no reflection, hard wall, and potential relief exit terminations with a variety of triangular element orientations. For this group of problems, the correlation between the accuracy of the solution and the orientation of the linear triangle is examined. Nonsymmetric element patterns are found to give generally poor results in the model problems investigated, particularly for cases where standing waves exist. For a fixed number of vertical elements, the results showed that symmetric element patterns give much better agreement with corresponding exact analytical results. In laminated wave guide application, the symmetric pyramid pattern is convenient to use and is shown to give excellent results.

Research on a bimorph piezoelectric deformable mirror for adaptive optics in optical telescope.

PubMed

Wang, Hairen

2017-04-03

We have proposed a discrete-layout bimorph piezoelectric deformable mirror (DBPDM) and developed its realistic electromechanical model. Compared with the conventional piezoelectric deformable mirror (CPDM) and the bimorph piezoelectric deformable mirror (BPDM), the DBPDM has both a larger stroke and a higher resonance frequency by integrating the strengths of the CPDM and the BPDM. To verify the advancement, a 21-elements DBPDM is studied in this paper. The results have suggested that the stroke of the DBPDM is larger than 10 microns and its resonance frequency is 53.3 kHz. Furthermore, numerical simulation is conducted on the deformation of the mirror using the realistic electromechanical model, and the dependence of the influence function upon the size of the radius of push pad is analyzed.

The calibration of an HF radar used for ionospheric research

NASA Astrophysics Data System (ADS)

From, W. R.; Whitehead, J. D.

1984-02-01

The HF radar on Bribie Island, Australia, uses crossed-fan beams produced by crossed linear transmitter and receiver arrays of 10 elements each to simulate a pencil beam. The beam points vertically when all the array elements are in phase, and is steerable by up to 20 deg off vertical at the central one of the three operating frequencies. Phase and gain changes within the transmitters and receivers are compensated for by an automatic system of adjustment. The 10 transmitting antennas are, as nearly as possible, physically identical as are the 10 receiving antennas. Antenna calibration using high flying aircraft or satellites is not possible. A method is described for using the ionospheric reflections to measure the polar diagram and also to correct for errors in the direction of pointing.

Evaluation of a Kinematically-Driven Finite Element Footstrike Model.

PubMed

Hannah, Iain; Harland, Andy; Price, Dan; Schlarb, Heiko; Lucas, Tim

2016-06-01

A dynamic finite element model of a shod running footstrike was developed and driven with 6 degree of freedom foot segment kinematics determined from a motion capture running trial. Quadratic tetrahedral elements were used to mesh the footwear components with material models determined from appropriate mechanical tests. Model outputs were compared with experimental high-speed video (HSV) footage, vertical ground reaction force (GRF), and center of pressure (COP) excursion to determine whether such an approach is appropriate for the development of athletic footwear. Although unquantified, good visual agreement to the HSV footage was observed but significant discrepancies were found between the model and experimental GRF and COP readings (9% and 61% of model readings outside of the mean experimental reading ± 2 standard deviations, respectively). Model output was also found to be highly sensitive to input kinematics with a 120% increase in maximum GRF observed when translating the force platform 2 mm vertically. While representing an alternative approach to existing dynamic finite element footstrike models, loading highly representative of an experimental trial was not found to be achievable when employing exclusively kinematic boundary conditions. This significantly limits the usefulness of employing such an approach in the footwear development process.

Effects of Chemistry on Vertical Dust Motion in Early Protoplanetary Disks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyazaki, Yoshinori; Korenaga, Jun

We propose the possibility of a new phenomenon affecting the settling of dust grains at the terrestrial region in early protoplanetary disks. Sinking dust grains evaporate in a hot inner region during the early stage of disk evolution, and the effects of condensation and evaporation on vertical dust settling can be significant. A 1D dust settling model considering both physical and chemical aspects is presented in this paper. Modeling results show that dust grains evaporate as they descend into the hotter interior and form a condensation front, above which dust-composing major elements, Mg, Si, and Fe, accumulate, creating a largemore » temperature gradient. Repeated evaporation at the front inhibits grain growth, and small grain sizes elevate the opacity away from the midplane. Self-consistent calculations, including radiative heat transfer and condensation theory, suggest that the mid-disk temperature could be high enough for silicates to remain evaporated longer than previous estimates. The formation of a condensation front leads to contrasting settling behaviors between highly refractory elements, such as Al and Ca, and moderately refractory elements, such as Mg, Si, and Fe, suggesting that elemental abundance in planetesimals may not be a simple function of volatility.« less

Effects of Chemistry on Vertical Dust Motion in Early Protoplanetary Disks

NASA Astrophysics Data System (ADS)

Miyazaki, Yoshinori; Korenaga, Jun

2017-11-01

We propose the possibility of a new phenomenon affecting the settling of dust grains at the terrestrial region in early protoplanetary disks. Sinking dust grains evaporate in a hot inner region during the early stage of disk evolution, and the effects of condensation and evaporation on vertical dust settling can be significant. A 1D dust settling model considering both physical and chemical aspects is presented in this paper. Modeling results show that dust grains evaporate as they descend into the hotter interior and form a condensation front, above which dust-composing major elements, Mg, Si, and Fe, accumulate, creating a large temperature gradient. Repeated evaporation at the front inhibits grain growth, and small grain sizes elevate the opacity away from the midplane. Self-consistent calculations, including radiative heat transfer and condensation theory, suggest that the mid-disk temperature could be high enough for silicates to remain evaporated longer than previous estimates. The formation of a condensation front leads to contrasting settling behaviors between highly refractory elements, such as Al and Ca, and moderately refractory elements, such as Mg, Si, and Fe, suggesting that elemental abundance in planetesimals may not be a simple function of volatility.

Investigation of the influence of vertical force on the contact between truck tyre and road using finite element analyses

NASA Astrophysics Data System (ADS)

Moisescu, Alexandra-Raluca; Anghelache, Gabriel

2017-10-01

In the modern context of automobile integration with the emerging technologies of the interconnected society, the interaction between tyre and road is an element of major importance for automobile safety systems such as the intelligent tyres, as well as for passenger comfort, fuel economy, environmental protection, infrastructure and vehicle durability. The tyre-road contact generates the distribution of forces exerted on each unit area in the contact patch, therefore the distribution of contact stresses on three orthogonal directions. The numerical investigation of stresses distribution in the contact patch requires the development of finite element models capable of accurately describing the interaction between tyre and rolling surface. The complex finite element model developed for the 11R22.5 truck tyre has been used for investigating the influence of vertical force on the distributions of contact stresses. In addition to these contributions, the paper presents aspects related to the simulation of truck tyre radial stiffness. The influence of tyre rolling has not been taken into consideration, as the purpose of the current research is the investigation of tyre-road contact in stationary conditions.

Smart wing rotation and trailing-edge vortices enable high frequency mosquito flight

PubMed Central

Bomphrey, Richard J.; Nakata, Toshiyuki; Phillips, Nathan; Walker, Simon M.

2017-01-01

Summary Mosquitoes exhibit unique wing kinematics; their long, slender wings flap at remarkably high frequencies for their size (>800 Hz) and with lower stroke amplitudes than any other insect group1. This shifts weight support away from the translation-dominated, aerodynamic mechanisms used by most insects2, as well as by helicopters and aeroplanes, towards poorly understood rotational mechanisms that occur when pitching at the end of each half-stroke. Here we report wing kinematics and solve the full Navier-Stokes equations using computational fluid dynamics with overset grids and validate our results with in vivo flow measurements. We show that, while familiar separated flow patterns are used by mosquitoes, much of the aerodynamic force that supports their weight is generated in a manner unlike any previously described flying animal. In total, there are three key features: leading-edge vortices (a well-known mechanism that appears to be almost ubiquitous in insect flight), trailing-edge vortices caused by a novel form of wake capture at stroke reversal, and rotational drag. The two new elements are largely independent of the wing velocity, instead relying on rapid changes in the pitch angle (wing rotation) at the end of each half stroke, and are therefore relatively immune to the shallow flapping amplitude. Moreover, these mechanisms are particularly well-suited to high-aspect ratio mosquito wings. PMID:28355184

Smart wing rotation and trailing-edge vortices enable high frequency mosquito flight

NASA Astrophysics Data System (ADS)

Bomphrey, Richard J.; Nakata, Toshiyuki; Phillips, Nathan; Walker, Simon M.

2017-03-01

Mosquitoes exhibit unusual wing kinematics; their long, slender wings flap at remarkably high frequencies for their size (>800 Hz)and with lower stroke amplitudes than any other insect group. This shifts weight support away from the translation-dominated, aerodynamic mechanisms used by most insects, as well as by helicopters and aeroplanes, towards poorly understood rotational mechanisms that occur when pitching at the end of each half-stroke. Here we report free-flight mosquito wing kinematics, solve the full Navier-Stokes equations using computational fluid dynamics with overset grids, and validate our results with in vivo flow measurements. We show that, although mosquitoes use familiar separated flow patterns, much of the aerodynamic force that supports their weight is generated in a manner unlike any previously described for a flying animal. There are three key features: leading-edge vortices (a well-known mechanism that appears to be almost ubiquitous in insect flight), trailing-edge vortices caused by a form of wake capture at stroke reversal, and rotational drag. The two new elements are largely independent of the wing velocity, instead relying on rapid changes in the pitch angle (wing rotation) at the end of each half-stroke, and they are therefore relatively immune to the shallow flapping amplitude. Moreover, these mechanisms are particularly well suited to high aspect ratio mosquito wings.

Experimental stroke protection induced by 4-hydroxybenzyl alcohol is cancelled by bacitracin.

PubMed

Descamps, Elodie; Petrault-Laprais, Maud; Maurois, Pierre; Pages, Nicole; Bac, Pierre; Bordet, Régis; Vamecq, Joseph

2009-06-01

Induction of protein disulfide isomerase (PDI) is validated as a main mechanism by which 4-hydroxybenzyl alcohol (4-HBA), an active principle of Gastrodia elata Blume, reduces cerebral infarct volumes in a murine model of focal brain ischemia/reperfusion. In contrast to its position isomers, i.e. 3-hydroxybenzyl alcohol (3-HBA) and 2-hydroxybenzyl alcohol (2-HBA), and to aliphatic diols (1,4-butanediol and 1,5-pentanediol), 4-HBA administered intravenously at 25 mg/kg protected mice, significantly reducing total, cortical and sub-cortical infarct volumes by 42, 28 and 55%, respectively. All compounds, 4-HBA included, were devoid of antioedematous properties. Only the stroke protective 4-HBA, but neither 3-HBA nor 2-HBA, was capable of significantly inducing PDI in intact mouse brains. Stroke protection was fully prevented by bacitracin (500 mg/kg), a known inhibitor of PDI, which, without affecting basal brain PDI levels, altered the ability of 4-HBA to induce significantly PDI in intact brains. Taken as a whole, our data indicate that stroke protection induced by 4-HBA involves PDI as a key player, making this protein a valuable target to control brain injury disorders. The fact that 4-HBA, at doses up to 200mg/kg, was devoid of neurotoxicity in the rotarod test is also a decisive element to promote the neuroprotective use of this plant compound.

Effects of interactive metronome training on upper extremity function, ADL and QOL in stroke patients.

PubMed

Yu, Ga-Hui; Lee, Jae-Shin; Kim, Su-Kyoung; Cha, Tae-Hyun

2017-01-01

Rhythm and timing training is stimulation that substitutes for a damaged function controls muscular movement or temporal element, which has positive impacts on the neurological aspect and movement of the brain. This study is to assess the changes caused by rhythm and timing training using an interactive metronome (IM) on upper extremity function, ADL and QOL in stroke patients. In order to assess the effects of IM training, a group experiment was conducted on 30 stroke patients. Twelve sessions of IM training were provided for the experimental group three times a week for four weeks, while the control group was trained with a Bilateral arm Self-Exercise (BSE) for the same period. Both groups were evaluated by pre- and post-tests through MFT, MAL, K-MBI and SS-QOL. There were more statistically significant differences (<0.05) in the total score of MFT and the finger control item in the IM Group than in the BSE Group. With respect to ADL, there were more statistically significant differences (<0.05) in the total score of K-MBI and the dressing item in the IM Group than in the BSE Group. The study proposes that IM training can be applied as an occupational therapy program in patients with various diseases who need to adjust the time for performing movements as well as stroke patients.

Analysis of Flexible Car Body of Straddle Monorail Vehicle

NASA Astrophysics Data System (ADS)

Zhong, Yuanmu

2018-03-01

Based on the finite element model of straddle monorail vehicle, a rigid-flexible coupling dynamic model considering vehicle body’s flexibility is established. The influence of vertical stiffness and vertical damping of the running wheel on the modal parameters of the car body is analyzed. The effect of flexible car body on modal parameters and vehicle ride quality is also studied. The results show that when the vertical stiffness of running wheel is less than 1 MN / m, the car body bounce and pitch frequency increase with the increasing of the vertical stiffness of the running wheel, when the running wheel vertical stiffness is 1MN / m or more, car body bounce and pitch frequency remained unchanged; When the vertical stiffness of the running wheel is below 1.8 MN / m, the vehicle body bounce and pitch damping ratio increase with the increasing of the vertical stiffness of the running wheel; When the running wheel vertical stiffness is 1.8MN / m or more, the car body bounce and pitch damping ratio remained unchanged; The running wheel vertical damping on the car body bounce and pitch frequency has no effect; Car body bounce and pitch damping ratio increase with the increasing of the vertical damping of the running wheel. The flexibility of the car body has no effect on the modal parameters of the car, which will improve the vehicle ride quality index.

A low-cost simulation platform for flapping wing MAVs

NASA Astrophysics Data System (ADS)

Kok, J. M.; Chahl, J. S.

2015-03-01

This paper describes the design of a flight simulator for analysing the systems level performance of a Dragonfly-Inspired Micro Air Vehicle (DIMAV). A quasi-steady blade element model is used to analyse the aerodynamic forces. Aerodynamic and environmental forces are then incorporated into a real world flight dynamics model to determine the dynamics of the DIMAV system. The paper also discusses the implementation of the flight simulator for analysing the manoeuvrability of a DIMAV, specifically several modes of flight commonly found in dragonflies. This includes take-off, roll turns and yaw turns. Our findings with the simulator are consistent with results from wind tunnel studies and slow motion cinematography of dragonflies. In the take-off mode of flight, we see a strong dependence of take-off accelerations with flapping frequency. An increase in wing-beat frequency of 10% causes the maximum vertical acceleration to increase by 2g which is similar to that of dragonflies in nature. For the roll and yaw modes of manoeuvring, asymmetrical inputs are applied between the left and right set of wings. The flapping amplitude is increased on the left pair of wings which causes a time averaged roll rate to the right of 1.76rad/s within two wing beats. In the yaw mode, the stroke plane angle is reduced in the left pair of wings to initiate the yaw manoeuvre. In two wing beats, the time averaged yaw rate is 2.54rad/s.

Common data elements for clinical research in mitochondrial disease: a National Institute for Neurological Disorders and Stroke project.

PubMed

Karaa, Amel; Rahman, Shamima; Lombès, Anne; Yu-Wai-Man, Patrick; Sheikh, Muniza K; Alai-Hansen, Sherita; Cohen, Bruce H; Dimmock, David; Emrick, Lisa; Falk, Marni J; McCormack, Shana; Mirsky, David; Moore, Tony; Parikh, Sumit; Shoffner, John; Taivassalo, Tanja; Tarnopolsky, Mark; Tein, Ingrid; Odenkirchen, Joanne C; Goldstein, Amy

2017-05-01

The common data elements (CDE) project was developed by the National Institute of Neurological Disorders and Stroke (NINDS) to provide clinical researchers with tools to improve data quality and allow for harmonization of data collected in different research studies. CDEs have been created for several neurological diseases; the aim of this project was to develop CDEs specifically curated for mitochondrial disease (Mito) to enhance clinical research. Nine working groups (WGs), composed of international mitochondrial disease experts, provided recommendations for Mito clinical research. They initially reviewed existing NINDS CDEs and instruments, and developed new data elements or instruments when needed. Recommendations were organized, internally reviewed by the Mito WGs, and posted online for external public comment for a period of eight weeks. The final version was again reviewed by all WGs and the NINDS CDE team prior to posting for public use. The NINDS Mito CDEs and supporting documents are publicly available on the NINDS CDE website ( https://commondataelements.ninds.nih.gov/ ), organized into domain categories such as Participant/Subject Characteristics, Assessments, and Examinations. We developed a comprehensive set of CDE recommendations, data definitions, case report forms (CRFs), and guidelines for use in Mito clinical research. The widespread use of CDEs is intended to enhance Mito clinical research endeavors, including natural history studies, clinical trial design, and data sharing. Ongoing international collaboration will facilitate regular review, updates and online publication of Mito CDEs, and support improved consistency of data collection and reporting.

Photovoltaic building sheathing element with anti-slide features

DOEpatents

Keenihan, James R.; Langmaid, Joseph A.; Lopez, Leonardo C.

2015-09-08

The present invention is premised` upon an assembly that includes at least a photovoltaic building sheathing element capable of being affixed on a building structure, the photovoltaic building sheathing element. The element including a photovoltaic cell assembly, a body portion attached to one or more portions of the photovoltaic cell assembly; and at feast a first and a second connector assembly capable of directly or indirectly electrically connecting the photovoltaic cell assembly to one or more adjoining devices; wherein the body portion includes one or more geometric features adapted to engage a vertically adjoining device before installation.

VHICA, a New Method to Discriminate between Vertical and Horizontal Transposon Transfer: Application to the Mariner Family within Drosophila.

PubMed

Wallau, Gabriel Luz; Capy, Pierre; Loreto, Elgion; Le Rouzic, Arnaud; Hua-Van, Aurélie

2016-04-01

Transposable elements (TEs) are genomic repeated sequences that display complex evolutionary patterns. They are usually inherited vertically, but can occasionally be transmitted between sexually independent species, through so-called horizontal transposon transfers (HTTs). Recurrent HTTs are supposed to be essential in life cycle of TEs, which are otherwise destined for eventual decay. HTTs also impact the host genome evolution. However, the extent of HTTs in eukaryotes is largely unknown, due to the lack of efficient, statistically supported methods that can be applied to multiple species sequence data sets. Here, we developed a new automated method available as a R package "vhica" that discriminates whether a given TE family was vertically or horizontally transferred, and potentially infers donor and receptor species. The method is well suited for TE sequences extracted from complete genomes, and applicable to multiple TEs and species at the same time. We first validated our method using Drosophila TE families with well-known evolutionary histories, displaying both HTTs and vertical transmission. We then tested 26 different lineages of mariner elements recently characterized in 20 Drosophila genomes, and found HTTs in 24 of them. Furthermore, several independent HTT events could often be detected within the same mariner lineage. The VHICA (Vertical and Horizontal Inheritance Consistence Analysis) method thus appears as a valuable tool to analyze the evolutionary history of TEs across a large range of species. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

The effectiveness of element downsizing on a three-dimensional finite element model of bone trabeculae in implant biomechanics.

PubMed

Sato, Y; Wadamoto, M; Tsuga, K; Teixeira, E R

1999-04-01

More validity of finite element analysis in implant biomechanics requires element downsizing. However, excess downsizing needs computer memory and calculation time. To investigate the effectiveness of element downsizing on the construction of a three-dimensional finite element bone trabeculae model, with different element sizes (600, 300, 150 and 75 microm) models were constructed and stress induced by vertical 10 N loading was analysed. The difference in von Mises stress values between the models with 600 and 300 microm element sizes was larger than that between 300 and 150 microm. On the other hand, no clear difference of stress values was detected among the models with 300, 150 and 75 microm element sizes. Downsizing of elements from 600 to 300 microm is suggested to be effective in the construction of a three-dimensional finite element bone trabeculae model for possible saving of computer memory and calculation time in the laboratory.

Fast acting multiple element valve

DOEpatents

Yang, Jefferson Y. S.; Wada, James M.

1991-01-01

A plurality of slide valve elements having plural axial-spaced annular parts and an internal slide are inserted into a bulkhead in a fluid conduit from a downstream side of the bulkhead, locked in place by a bayonet coupling and set screw, and project through the bulkhead into the upstream conduit. Pneumatic lines connecting the slide valve element actuator to pilot valves are brought out the throat of the valve element to the downstream side. Pilot valves are radially spaced around the exterior of the valve to permit the pneumatic lines to be made identical, thereby to minimize adverse timing tolerances in operation due to pressure variations. Ring manifolds surround the valve adjacent respective pilot valve arrangements to further reduce adverse timing tolerances due to pressure variations, the manifolds being directly connected to the respective pilot valves. Position sensors are provided the valve element slides to signal the precise time at which a slide reaches or passes through a particular point in its stroke to initiate a calibrated timing function.

Hypoxia Response Element-Regulated MMP-9 Promotes Neurological Recovery via Glial Scar Degradation and Angiogenesis in Delayed Stroke.

PubMed

Cai, Hongxia; Ma, Yuanyuan; Jiang, Lu; Mu, Zhihao; Jiang, Zhen; Chen, Xiaoyan; Wang, Yongting; Yang, Guo-Yuan; Zhang, Zhijun

2017-06-07

Matrix metalloproteinase 9 (MMP-9) plays a beneficial role in the delayed phase of middle cerebral artery occlusion (MCAO). However, the mechanism is obscure. Here, we constructed hypoxia response element (HRE)-regulated MMP-9 to explore its effect on glial scars and neurogenesis in delayed ischemic stroke. Adult male Institute of Cancer Research (ICR) mice underwent MCAO and received a stereotactic injection of lentivirus carrying HRE-MMP-9 or normal saline (NS)/lentivirus-GFP 7 days after ischemia. We found that HRE-MMP-9 improved neurological outcomes, reduced ischemia-induced brain atrophy, and degraded glial scars (p < 0.05). Furthermore, HRE-MMP-9 increased the number of microvessels in the peri-infarct area (p < 0.001), which may have been due to the accumulation of endogenous endothelial progenitor cells (EPCs) in the peri-infarct area after glial scar degradation. Finally, HRE-MMP-9 increased the number of bromodeoxyuridine-positive (BrdU + )/NeuN + cells and the expression of PSD-95 in the peri-infarct area (p < 0.01). These changes could be blocked by vascular endothelial growth factor receptor 2 (VEGFR2) inhibitor SU5416 and MMP-9 inhibitor 2-[[(4-phenoxyphenyl)sulfonyl]methyl]-thiirane (SB-3CT). Our results provided a novel mechanism by which glial scar degradation and vascular endothelial growth factor (VEGF)/VEGFR2-dependent angiogenesis may be key procedures for neurological recovery in delayed ischemic stroke after HRE-MMP-9 treatment. Therefore, HRE-MMP-9 overexpression in the delayed ischemic brain is a promising approach for neurological recovery. Copyright © 2017 The American Society of Gene and Cell Therapy. Published by Elsevier Inc. All rights reserved.

Mediterranean diet in healthy lifestyle and prevention of stroke.

PubMed

Demarin, Vida; Lisak, Marijana; Morović, Sandra

2011-03-01

Several studies demonstrated the beneficial and preventive role of Mediterranean diet in the occurrence of cardiovascular diseases, chronic neurodegenerative diseases and neoplasms, obesity and diabetes. In randomized intervention trials, Mediterranean diet improved endothelial function and significantly reduced waist circumference, plasma glucose, serum insulin and homeostasis model assessment score in metabolic syndrome. Several studies support favorable effects of Mediterranean diet on plasma lipid profile: reduction of total and plasma LDL cholesterol levels, plasma triglyceride levels, and apo-B and VLDL concentrations, and an increase in plasma HDL cholesterol levels. This effect is associated with increased plasma antioxidant capacity, improved endothelial function, reduced insulin resistance, and reduced incidence of the metabolic syndrome. The beneficial impact of fish consumption on the risk of cardiovascular diseases is the result of synergistic effects of nutrients in fish. Fish is considered an excellent source of protein with low saturated fat, nutritious trace elements, long-chain omega-3 polyunsaturated fatty acids (LCn3PUFAs), and vitamins D and B. Fish consumption may be inversely associated with ischemic stroke but not with hemorrhagic stroke because of the potential antiplatelet aggregation property of LCn3PUFAs. Total stroke risk reduction was statistically significant for fish intake once per week, while the risk of stroke was lowered by 31% in individuals who ate fish 5 times or more per week. In the elderly, moderate consumption of tuna/other fish, but not fried fish, was associated with lower prevalence of subclinical infarcts and white matter abnormalities on MRI examination. Dietary intake of omega-3 fatty acids in a moderate-to-high range does not appear to be associated with reduced plaque, but is negatively associated with carotid artery intima-media thickness. Greater adherence to Mediterranean diet is associated with significant reduction in overall mortality, mortality from cardiovascular diseases and stroke, incidence of or mortality from cancer, and incidence of Parkinson's disease and Alzheimer's disease and mild cognitive impairment.

Getting coal to go with the flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dumbaugh, G.D.

1984-01-01

There are three accepted methods of recovering storage piles. They are surface reclaiming, sub-grade hopper sections or bins, and flat surface storage with ground level ports. In general, the decision to use either approach is a matter of economics, reliability, labor intensity, and other related practical factors. The concept of induced vertical flow of bulk solids was initiated in 1962 with the birth of the bin activator. Its performance was at times questionable until the elusive cycle type operation was finally discovered. This solved the problems of coupling induced vertical flow units with feeders. Surprisingly, an operator in a cementmore » plant was the first to demonstrate this principle of operation in 1965, but it needed at least five more years for it to be fully understood. The storage pile discharger with its drawdown skirt and unique stroke action was developed out of sheer necessity in 1964. However, it was not until 1979 that the railcar discharger was introduced. Frankly, it took that long to recognize a railcar could be temporarily converted to a huge rectangular shaped activated binexclamation Significantly, all induced vertical flow units are designed and operated for the sole purpose of bulk solid storage withdrawal. They have no other function. For many reasons, the successful evolution of the concept of induced vertical flow of bulk solids has been one of more perspiration than of meditation. Armed with time proven application guidelines and cycle type operation to minimize the effects of feeder flow streams, bin activators, activated bins, storage pile dischargers, and railcar dischargers can be applied confidently and predictably.« less

A System for the Measurement of the Subjective Visual Vertical using a Virtual Reality Device.

PubMed

Negrillo-Cárdenas, José; Rueda-Ruiz, Antonio J; Ogayar-Anguita, Carlos J; Lomas-Vega, Rafael; Segura-Sánchez, Rafael J

2018-05-31

The Subjective Visual Vertical (SVV) is a common test for evaluating the perception of verticality. Altered verticality has been connected with disorders in the otolithic, visual or proprioceptive systems, caused by stroke, Parkinson's disease or multiple sclerosis, among others. Currently, this test is carried out using a variety of specific, mostly homemade apparatuses that include moving planes, buckets, hemispheric domes or a line projected in a screen. Our aim is to develop a flexible, inexpensive, user-friendly and easily extensible system based on virtual reality for the measurement of the SVV and several related visual diagnostic tests, and validate it through an experimental evaluation. Two different hardware configurations were tested with 50 healthy volunteers in a controlled environment; 28 of them were males and 22 females, with ages ranging from 18 to 49 years, being 23 the average age. The Intraclass Correlation Coefficient (ICC) was computed in each device. In addition, a usability survey was conducted. ICC = 0.85 in the first configuration (CI = 0.75-0.92), ICC = 0.76 in the second configuration (CI = 0.61-0.87), both with 95% of confidence, which means a substantial reliability. Moreover, 92.2% of subjects rated the usability of the system as "very good". Our evaluation showed that the proposed system is suitable for the measurement of SVV in healthy subjects. The next step is to perform a more elaborated experimentation on patients and compare the results with the measurements obtained from traditional methods.

Trampoline Effect: Observations and Modeling

NASA Astrophysics Data System (ADS)

Guyer, R.; Larmat, C. S.; Ulrich, T. J.

2009-12-01

The Iwate-Miyagi earthquake at site IWTH25 (14 June 2008) had large, asymmetric at surface vertical accelerations prompting the sobriquet trampoline effect (Aoi et. al. 2008). In addition the surface acceleration record showed long-short waiting time correlations and vertical-horizontal acceleration correlations. A lumped element model, deduced from the equations of continuum elasticity, is employed to describe the behavior at this site in terms of a surface layer and substrate. Important ingredients in the model are the nonlinear vertical coupling between the surface layer and the substrate and the nonlinear horizontal frictional coupling between the surface layer and the substrate. The model produces results in qualitative accord with observations: acceleration asymmetry, Fourier spectrum, waiting time correlations and vertical acceleration-horizontal acceleration correlations. [We gratefully acknowledge the support of the U. S. Department of Energy through the LANL/LDRD Program for this work].

Texture segregation, surface representation and figure-ground separation.

PubMed

Grossberg, S; Pessoa, L

1998-09-01

A widespread view is that most texture segregation can be accounted for by differences in the spatial frequency content of texture regions. Evidence from both psychophysical and physiological studies indicate, however, that beyond these early filtering stages, there are stages of 3-D boundary segmentation and surface representation that are used to segregate textures. Chromatic segregation of element-arrangement patterns--as studied by Beck and colleagues--cannot be completely explained by the filtering mechanisms previously employed to account for achromatic segregation. An element arrangement pattern is composed of two types of elements that are arranged differently in different image regions (e.g. vertically on top and diagonally on the bottom). FACADE theory mechanisms that have previously been used to explain data about 3-D vision and figure-ground separation are here used to simulate chromatic texture segregation data, including data with equiluminant elements on dark or light homogeneous backgrounds, or backgrounds composed of vertical and horizontal dark or light stripes, or horizontal notched stripes. These data include the fact that segregation of patterns composed of red and blue squares decreases with increasing luminance of the interspaces. Asymmetric segregation properties under 3-D viewing conditions with the equiluminant elements close or far are also simulated. Two key model properties are a spatial impenetrability property that inhibits boundary grouping across regions with non-collinear texture elements and a boundary-surface consistency property that uses feedback between boundary and surface representations to eliminate spurious boundary groupings and separate figures from their backgrounds.

An investigation of thoracic and lumbar cancellous vertebral architecture using power-spectral analysis of plain radiographs*

PubMed Central

Buck, AM; Price, RI; Sweetman, IM; Oxnard, CE

2002-01-01

The internal architecture of the vertebral bodies spanning the levels T1 to L5 in seven male columns was studied using mammographic-resolution radiographs of 2.5-mm-thick planar parasagittal slices. The overlapping radiographic shadows of vertebral trabeculae combined in the image to form a series of ‘elements’, broadly representative of the cancellous structure. The orientations and sizes of these elements were analysed by applying the Fast Fourier transform (FFT) to the digitized radiographic images. Elements aligned in the ‘vertical’ orientation, along the long axis of the column, were the most prominent for all vertebral levels. The relative prominence of horizontal to vertical elements was generally constant along the column below T5. In contrast, the relative prominence of oblique to vertical elements declined in the cranio-caudal direction, particularly in individuals aged ≥ 60 years. The ratio of ‘large’ (x > 0.3 mm) to ‘small’ (0.15 mm ≤ x ≤ 0.3 mm) elements was unchanged cranio-caudally in specimens < 60 years. However, in individuals ≥ 60 years, large elements increased in relative prominence in the caudal direction. These results suggest that a basic orthogonal pattern of trabeculae is found along the male human spine, regardless of differences in vertebral body size. Power-spectral analysis is shown to yield information summarizing the predominant orientations and sizes of radiographically rendered architectural elements of vertebral cancellous bone, to define the effects of ageing on architecture, and to identify broad structural differences between vertebral levels in the adult male spine. PMID:12090391

The Responsiveness and Correlation between Fugl-Meyer Assessment, Motor Status Scale, and the Action Research Arm Test in Chronic Stroke with Upper-Extremity Rehabilitation Robotic Training

ERIC Educational Resources Information Center

Wei, Xi-Jun; Tong, Kai-yu; Hu, Xiao-ling

2011-01-01

Responsiveness of clinical assessments is an important element in the report of clinical effectiveness after rehabilitation. The correlation could reflect the validity of assessments as an indication of clinical performance before and after interventions. This study investigated the correlation and responsiveness of Fugl-Meyer Assessment (FMA),…

Modelling the long-term vertical dynamics of salt marshes

NASA Astrophysics Data System (ADS)

Zoccarato, Claudia; Teatini, Pietro

2017-04-01

Salt marshes are vulnerable environments hosting complex interactions between physical and biological processes with a strong influence on the dynamics of the marsh evolution. The estimation and prediction of the elevation of a salt-marsh platform is crucial to forecast the marsh growth or regression under different scenarios considering, for example, the potential climate changes. The long-term vertical dynamics of a salt marsh is predicted with the aid of an original finite-element (FE) numerical model accounting for the marsh accretion and compaction and for the variation rates of the relative sea level rise, i.e., land subsidence of the marsh basement and eustatic rise of the sea level. The accretion term considers the vertical sedimentation of organic and inorganic material over the marsh surface, whereas the compaction reflects the progressive consolidation of the porous medium under the increasing load of the overlying younger deposits. The modelling approach is based on a 2D groundwater flow simulator, which provides the pressure evolution within a compacting/accreting vertical cross-section of the marsh assuming that the groundwater flow obeys the relative Darcy's law, coupled to a 1D vertical geomechanical module following Terzaghi's principle of effective intergranular stress. Soil porosity, permeability, and compressibility may vary with the effective intergranular stress according to empirically based relationships. The model also takes into account the geometric non-linearity arising from the consideration of large solid grain movements by using a Lagrangian approach with an adaptive FE mesh. The element geometry changes in time to follow the deposit consolidation and the element number increases in time to follow the sedimentation of new material. The numerical model is tested on different realistic configurations considering the influence of (i) the spatial distribution of the sedimentation rate in relation to the distance from the marsh margin, (ii) the material heterogeneity (mineral vs organic), and (iii) different sequences and times of deposition. Additional experiments are performed to investigate the effect of a stochastic distribution of the material properties to account for the typical high variability of such ecosystems. The characteristic time spanned by the simulations is thousands of years, roughly corresponding to the Holocene.

Crashworthiness design modifications for locomotive and cab car anticlimbing systems

DOT National Transportation Integrated Search

2003-02-01

This study addressed the feasibility of incorporating complete anticlimbing systems into both passenger and freight locomotives. Complete systems include pushback couplers, vertically interlocking anticlimber elements, and zones specifically designed...

Control-Volume Analysis Of Thrust-Augmenting Ejectors

NASA Technical Reports Server (NTRS)

Drummond, Colin K.

1990-01-01

New method of analysis of transient flow in thrust-augmenting ejector based on control-volume formulation of governing equations. Considered as potential elements of propulsion subsystems of short-takeoff/vertical-landing airplanes.

Guided training relative to direct skill training for individuals with cognitive impairments after stroke: a pilot randomized trial

PubMed Central

Skidmore, Elizabeth R.; Butters, Meryl; Whyte, Ellen; Grattan, Emily; Shen, Jennifer; Terhorst, Lauren

2016-01-01

Objective To examine the effects of direct skill training and guided training for promoting independence after stroke. Design Single-blind randomized pilot study. Setting Inpatient rehabilitation facility. Participants Forty-three participants in inpatient rehabilitation with acute stroke and cognitive impairments. Interventions Participants were randomized to receive direct skill training (n=22, 10 sessions as adjunct to usual inpatient rehabilitation) or guided training (n=21, same dose). Main Outcome Measure The Functional Independence Measure assessed independence at baseline, rehabilitation discharge, and months 3, 6, and 12. Results Linear mixed models (random intercept, other effects fixed) revealed a significant intervention by time interaction (F4,150=5.11, p<0.001), a significant main effect of time (F4,150=49.25, p<0.001), and a significant effect of stroke severity (F1,150=34.46, p<.001). There was no main effect of intervention (F1,150=0.07, p=0.79). Change in Functional Independence Measures scores was greater for the DIRECT group at rehabilitation discharge (effect size of between group differences, d=0.28) and greater for the GUIDE group at months 3 (d=0.16), 6 (d=0.39), and 12 (d=0.53). The difference between groups in mean 12 month change scores was 10.57 points. Conclusions Guided training, provided in addition to usual care, offered a small advantage in the recovery of independence, relative to direct skill training. Future studies examining guided training in combination with other potentially potent intervention elements may further advise best practices in rehabilitation for individuals with cognitive impairments after acute stroke. PMID:27794487

Measure of functional independence dominates discharge outcome prediction after inpatient rehabilitation for stroke.

PubMed

Brown, Allen W; Therneau, Terry M; Schultz, Billie A; Niewczyk, Paulette M; Granger, Carl V

2015-04-01

Identifying clinical data acquired at inpatient rehabilitation admission for stroke that accurately predict key outcomes at discharge could inform the development of customized plans of care to achieve favorable outcomes. The purpose of this analysis was to use a large comprehensive national data set to consider a wide range of clinical elements known at admission to identify those that predict key outcomes at rehabilitation discharge. Sample data were obtained from the Uniform Data System for Medical Rehabilitation data set with the diagnosis of stroke for the years 2005 through 2007. This data set includes demographic, administrative, and medical variables collected at admission and discharge and uses the FIM (functional independence measure) instrument to assess functional independence. Primary outcomes of interest were functional independence measure gain, length of stay, and discharge to home. The sample included 148,367 people (75% white; mean age, 70.6±13.1 years; 97% with ischemic stroke) admitted to inpatient rehabilitation a mean of 8.2±12 days after symptom onset. The total functional independence measure score, the functional independence measure motor subscore, and the case-mix group were equally the strongest predictors for any of the primary outcomes. The most clinically relevant 3-variable model used the functional independence measure motor subscore, age, and walking distance at admission (r(2)=0.107). No important additional effect for any other variable was detected when added to this model. This analysis shows that a measure of functional independence in motor performance and age at rehabilitation hospital admission for stroke are predominant predictors of outcome at discharge in a uniquely large US national data set. © 2015 American Heart Association, Inc.

Reorganization of finger coordination patterns through motor exploration in individuals after stroke.

PubMed

Ranganathan, Rajiv

2017-09-11

Impairment of hand and finger function after stroke is common and affects the ability to perform activities of daily living. Even though many of these coordination deficits such as finger individuation have been well characterized, it is critical to understand how stroke survivors learn to explore and reorganize their finger coordination patterns for optimizing rehabilitation. In this study, I examine the use of a body-machine interface to assess how participants explore their movement repertoire, and how this changes with continued practice. Ten participants with chronic stroke wore a data glove and the finger joint angles were mapped on to the position of a cursor on a screen. The task of the participants was to move the cursor back and forth between two specified targets on a screen. Critically, the map between the finger movements and cursor motion was altered so that participants sometimes had to generate coordination patterns that required finger individuation. There were two phases to the experiment - an initial assessment phase on day 1, followed by a learning phase (days 2-5) where participants trained to reorganize their coordination patterns. Participants showed difficulty in performing tasks which had maps that required finger individuation, and the degree to which they explored their movement repertoire was directly related to clinical tests of hand function. However, over four sessions of practice, participants were able to learn to reorganize their finger movement coordination pattern and improve their performance. Moreover, training also resulted in improvements in movement repertoire outside of the context of the specific task during free exploration. Stroke survivors show deficits in movement repertoire in their paretic hand, but facilitating movement exploration during training can increase the movement repertoire. This suggests that exploration may be an important element of rehabilitation to regain optimal function.

Modular off-axis solar concentrator

DOEpatents

Plesniak, Adam P; Hall, John C

2015-01-27

A solar concentrator including a housing defining a vertical axis and including a receiving wall connected to a reflecting wall to define an internal volume and an opening into the internal volume, wherein the reflecting wall defines at least one primary optical element, and wherein at least a portion of the reflecting wall includes a layer of reflective material, the housing further including a cover connected to the receiving wall and the reflecting wall to seal the opening, and at least one receiver mounted on the receiving wall such that a vertical axis of the receiver is disposed at a non-zero angle relative to the vertical axis of the housing, the receiver including at least one photovoltaic cell.

Heat and mass transfer in vertical porous medium due to partial heating

NASA Astrophysics Data System (ADS)

Salman Ahmed N., J.; Khan, T. M. Yunus; Ahamad, N. Ameer; Kamangar, Sarfaraz

2018-05-01

The investigation of heat and mass transfer adjacent to vertical plate subjected to partial heating of plate in multiple segments is carried out. A section of the plate is heated with isothermal temperature Th and the far away condition is maintained at ambient temperature T∞.. The vertical plate is maintained at constant concentration Ch as opposed to lowest concentration at far away condition. Finite element method is used and governing equations are converted into simple form of equations using Galerkin approach. The results are discussed in terms of contour plots. Study is carried out with respect to various physical parameters. The heat and mass transfer rate found to increase with increase in Rayleigh number.

Vibration analysis of the SA349/2 helicopter

NASA Technical Reports Server (NTRS)

Heffernan, Ruth; Precetti, Dominique; Johnson, Wayne

1991-01-01

Helicopter airframe vibration is examined using calculations and measurements for the SA349/2 research helicopter. The hub loads, which transmit excitations to the fuselage, are predicted using a comprehensive rotorcraft analysis and correlated with measuring hub loads. The predicted and measured hub loads are then coupled with finite element models representing the SA349/2 fuselage. The resulting vertical acceleration at the pilot seat is examined. Adjustments are made to the airframe structural models to examine the sensitivity of predicted vertical acceleration to the model. Changes of a few percent to the damping and frequency of specific models lead to large reductions in predicted vibration, and to major improvements in the correlations with measured pilot-seat vertical acceleration.

Implementation of higher-order vertical finite elements in ISSM v4.13 for improved ice sheet flow modeling over paleoclimate timescales

NASA Astrophysics Data System (ADS)

Cuzzone, Joshua K.; Morlighem, Mathieu; Larour, Eric; Schlegel, Nicole; Seroussi, Helene

2018-05-01

Paleoclimate proxies are being used in conjunction with ice sheet modeling experiments to determine how the Greenland ice sheet responded to past changes, particularly during the last deglaciation. Although these comparisons have been a critical component in our understanding of the Greenland ice sheet sensitivity to past warming, they often rely on modeling experiments that favor minimizing computational expense over increased model physics. Over Paleoclimate timescales, simulating the thermal structure of the ice sheet has large implications on the modeled ice viscosity, which can feedback onto the basal sliding and ice flow. To accurately capture the thermal field, models often require a high number of vertical layers. This is not the case for the stress balance computation, however, where a high vertical resolution is not necessary. Consequently, since stress balance and thermal equations are generally performed on the same mesh, more time is spent on the stress balance computation than is otherwise necessary. For these reasons, running a higher-order ice sheet model (e.g., Blatter-Pattyn) over timescales equivalent to the paleoclimate record has not been possible without incurring a large computational expense. To mitigate this issue, we propose a method that can be implemented within ice sheet models, whereby the vertical interpolation along the z axis relies on higher-order polynomials, rather than the traditional linear interpolation. This method is tested within the Ice Sheet System Model (ISSM) using quadratic and cubic finite elements for the vertical interpolation on an idealized case and a realistic Greenland configuration. A transient experiment for the ice thickness evolution of a single-dome ice sheet demonstrates improved accuracy using the higher-order vertical interpolation compared to models using the linear vertical interpolation, despite having fewer degrees of freedom. This method is also shown to improve a model's ability to capture sharp thermal gradients in an ice sheet particularly close to the bed, when compared to models using a linear vertical interpolation. This is corroborated in a thermal steady-state simulation of the Greenland ice sheet using a higher-order model. In general, we find that using a higher-order vertical interpolation decreases the need for a high number of vertical layers, while dramatically reducing model runtime for transient simulations. Results indicate that when using a higher-order vertical interpolation, runtimes for a transient ice sheet relaxation are upwards of 5 to 7 times faster than using a model which has a linear vertical interpolation, and this thus requires a higher number of vertical layers to achieve a similar result in simulated ice volume, basal temperature, and ice divide thickness. The findings suggest that this method will allow higher-order models to be used in studies investigating ice sheet behavior over paleoclimate timescales at a fraction of the computational cost than would otherwise be needed for a model using a linear vertical interpolation.

Aerial dispersal of particles emitted inside plant canopies: Application to the spread of plant diseases

NASA Astrophysics Data System (ADS)

Pan, Ying

This work combines numerical, experimental, and theoretical methods to investigate the dispersion of particles inside and above plant canopies. The large-eddy simulation (LES) approach is used to reproduce turbulence statistics and three-dimensional particle dispersion within the canopy roughness sublayer. The Eulerian description of conservation laws of fluid momentum and particle concentration implies that the continuous concentration field is advected by the continuous flow field. Within the canopy, modifications are required for the filtered momentum and concentration equations, because spatial filtering of flow variables and concentration field is inapplicable to a control volume consisting of both fluid and solid elements. In this work, the canopy region is viewed as a space occupied by air only. The sink of airflow momentum induced by forces acting on the surfaces of canopy elements is parameterized as a non-conservative virtual body force that dissipates the kinetic energy of the air. This virtual body force must reflect the characteristic of the surface forces exerted by canopy elements within the control volume, and is parameterized as a "drag force" following standard practice in LES studies. Specifically, the "drag force" is calculated as a product of a drag coefficient, the projected leaf area density, and the square of velocity. Using a constant drag coefficient, this model allows first-order accuracy in reproducing the vertically integrated sink of momentum within the canopy layer for airflows of high Reynolds number. The corresponding LES results of first- and second-order turbulence statistics are in good agreement with experimental data obtained in the field interior, within and just above mature maize canopies. However, the distribution of momentum sink among weak and strong events has not been well reproduced, inferred from the significant underestition of streamwise and vertical velocity skewness as well as the fractions of vertical momentum flux transported by strong events. Using a velocity-dependent drag coefficient that accounts for the effect of plant reconfiguration, the "drag force" model leads to LES results of streamwise and vertical velocity skewness as well as the fractions of vertical momentum flux transported by strong events in better agreement with field experimental data. The link between plant reconfiguration and turbulence dynamics within the canopy roughness sublayer is further investigated. The "reconfiguration drag model" using velocity-dependent drag coefficient is revised to incorporate a theoretical model of the force balance on individual crosswind blades. In the LES, the dimension and degree of the reconfiguration of canopy elements affect the magnitude and position of peak streamwise velocity skewness within the canopy as well as the fractions of vertical momentum flux transported by strong events. The streamwise velocity skewness is shown to be related to the penetration of strong events into the canopy, which is associated with the passage of canopy-scale coherent eddies. With the profile of mean vertical momentum flux constrained by field experimental data, changing the model of drag coefficient induces negligible changes in the vertically integrated "drag force" within the canopy layer. Consequently, first- and second-order turbulence statistics remain approximately the same. However, enhancing the rate of decrease of drag coefficient with increasing velocity increases the streamwise and vertical velocity skewness, the fractions of vertical momentum flux transported by strong events, as well as the ratio between vertical momentum flux transported by relatively strong head-down "sweeps" and relatively weak head-up "ejections." These results confirmed the inadequacy of describing the effects of canopy-scale coherent structures using just first- and second-order turbulence statistics. The filtered concentration equation is applied to the dispersion of particles within the canopy roughness sublayer, assuming that a virtual continuous concentration field is advected by a virtual continuous velocity field. A canopy deposition model is used to model the sink of particle concentration associated with the impaction, sedimentation, retention, and re-entrainment of particles on the surfaces of canopy elements. LES results of mean particle concentration field and mean ground deposition rate were evaluated against data obtained during an artificial continuous point-source release experiment. Accounting for the effect of reconfiguration by using a velocity dependent drag coefficient leads to better agreement between LES results and field experimental data of the mean particle concentration field, suggesting the importance of reproducing the distribution of momentum sink among weak and strong events for reproducing the dispersion of particles. LES results obtained using a velocity-dependent drag coefficient are analyzed to estimate essential properties for the occurrence of plant disease epidemics. The most interesting finding is that an existing analytical function can be used to model the crosswind-integrated mean concentration field above the canopy normalized by the escape fraction for particles released from the field interior. (Abstract shortened by ProQuest.).

Simulation of Rotor Blade Element Turbulence

DOT National Transportation Integrated Search

1995-01-01

A piloted, motion-based simulation of Sikorsky's Black Hawk helicopter was : used as a platform for the investigation of rotorcraft responses to vertical : turbulence. By using an innovative temporal and geometrical distribution : algorithm that pres...

Piezoelectric Nanostructures for Mechanical Energy Harvesting

NASA Astrophysics Data System (ADS)

Ardila, G.; Hinchet, R.; Montès, L.; Mouis, M.

2013-05-01

We present the most studied piezoelectric materials at the nanoscale and discuss their vertical integration into harvesting devices. Finite element method (FEM) simulations are used to obtain optimization guidelines rules of a specific design.

POWER REACTOR

DOEpatents

Zinn, W.H.

1958-07-01

A fast nuclear reactor system ls described for producing power and radioactive isotopes. The reactor core is of the heterogeneous, fluid sealed type comprised of vertically arranged elongated tubular fuel elements having vertical coolant passages. The active portion is surrounded by a neutron reflector and a shield. The system includes pumps and heat exchangers for the primary and secondary coolant circuits. The core, primary coolant pump and primary heat exchanger are disposed within an irapenforate tank which is filled with the primary coolant, in this case a liquid metal such as Na or NaK, to completely submerge these elements. The tank is completely surrounded by a thick walled concrete shield. This reactor system utilizes enriched uranium or plutonium as the fissionable material, uranium or thorium as a diluent and thorium or uranium containing less than 0 7% of the U/sup 235/ isotope as a fertile material.

Cs-137 geochronology, epithermal neutron activation analysis, and principal component analysis of heavy metals pollution of the Black Sea anoxic continental shelf sediments

NASA Astrophysics Data System (ADS)

Duliu, O. G.; Cristache, C.; Oaie, G.; Culicov, O. A.; Frontasyeva, M. V.

2009-04-01

Anthropogenic Cs-137 Gamma-ray Spectroscopy assay (GrSA) performed at the National Institute of Research and Development for Physics and Nuclear Engineering - Bucharest (Romania) in correlation with Epithermal Neutrons Activation Analysis (ENAA) performed at the Joint Institute of Nuclear Researches - Dubna (Russia) were used to investigate a 50 cm core containing unconsolidated sediments collected at a depth of 600 m off Romanian town of Constantza, located in the anoxic zone of the Black Sea Continental Shelf. A digital radiography showed the presence of about 265 distinct laminae, 1 to 3 mm thick, a fact attesting a stationary sedimentary process, completely free of bioturbation. After being radiographed, the core was sliced into 45 segments whose thickness gradually increased from 0.5 to 5 cm, such that the minimum thickness corresponded to the upper part of the core. From each segment two aliquots of about 0.5 g and 50 g were extracted for subsequent ENAA and Cs-137 GrSA. The Cs-137 vertical profile evidenced two maxima, one of them was very sharp and localized at a depth of 1 cm and the other very broad, almost undistinguished at about 8 cm depth, the first one being attributed to 1986 Chernobyl accident. Based on these date, we have estimated a sedimentation ratio of about 0.5 mm/year, value taken as reference for further assessment of recent pollution history. By means of ENAA we have determined the vertical content of five presumed pollutants, e.i. Zn, As, Br, Sn and Sb and of Sc, as natural, nonpolluting element. In the first case, all five elements presented a more or less similar vertical profile consisting of an almost exponential decrease for the first 10 cm below sediment surface followed by a plateau until the core base, i.e. 50 cm below surface, dependency better described by the equation: c(z) = c0 [1+k exp (-z/Z)] (1) where: where c(z) represents the concentration vertical profile; z represents depth (in absolute value); c0 represents the plateau concentrations; k represents the surface to plateau relative increment of concentration; Z represents concentration decrement: the depth at which the concentration becomes 1+k times greater than plateau one. Final results have shown with clarity that in the case of Zn, As, Br, Sn and Sb, the concentrations near sediment surface were 1.6 to 4.1 times greater then the plateau ones while Sc vertical profile, excepting some small fluctuations observed between 18 to 25 cm below surface, shown to be almost constant. Moreover, the concentration decrements Z of Zn, Br, Sn and Sb were almost coincident within one standard deviation while in the case of As, this coincidence appears within two standard deviation, these facts pleading for a comparable time evolution in the past 100 years. On the other hand, in the case of Sn and As, the maximum concentrations were reached 1 cm below the sediment surface, roughly corresponding to 1990 year, while the concentrations of all other three elements monotonously increases up to sediment surface. Further Principal Components Analysis of the data concerning the vertical distribution of all six elements illustrates the presence of two distinct clusters, one consisting of Zn, As, Br, Sn and Sb and the other on only of Sn, attesting both differences and similarities in the vertical distribution of considered elements. By comparing the experimental concentrations of all five elements with Romania Regulations concerning heavy metal pollution, we remarked that, by respect to these Regulations the only Zn, As, Br and Sb slightly exceeded normal accepted limits while the minimum alert concentrations were exceeded only in few cases by of As and Br, but no elements concentrations reached the intervention threshold. In our opinion, these results reflect the dynamics of the industrial activity in the riparian to Danube River European countries: a steady increase beginning with the last half of the XIX-th century followed by a slightly decline after the fall of Communism.

Pseudo-transient heat transfer in vertical Bridgman crystal growth of semi-transparent materials

NASA Astrophysics Data System (ADS)

Barvinschi, F.; Nicoara, I.; Santailler, J. L.; Duffar, T.

1998-11-01

The temperature distribution and the solid-liquid interface shape during semi-transparent crystal growth have been studied by modelling a vertical Bridgman technique, using a pseudo-transient approximation in an ideal configuration. The heat transfer equation and the boundary conditions have been solved by the finite-element method. It has been pointed out that the optical absorption coefficients of the liquid and solid phases have a major effect on the thermal field, especially on the shape and location of the crystallization interface.

Katanin spiral and ring structures shed light on power stroke for microtubule severing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zehr, Elena; Szyk, Agnieszka; Piszczek, Grzegorz

Microtubule-severing enzymes katanin, spastin and fidgetin are AAA ATPases critical for the biogenesis and maintenance of complex microtubule arrays in axons, spindles and cilia. Because of a lack of 3D structures, their mechanism has remained poorly understood. We report the first X-ray structure of the monomeric AAA katanin module and cryo-EM reconstructions of the hexamer in two conformations. These reveal an unexpected asymmetric arrangement of the AAA domains mediated by structural elements unique to severing enzymes and critical for their function. Our reconstructions show that katanin cycles between open spiral and closed ring conformations, depending on the ATP occupancy ofmore » a gating protomer that tenses or relaxes inter-protomer interfaces. Cycling of the hexamer between these conformations would provide the power stroke for microtubule severing.« less

Warm water and cool nests are best. How global warming might influence hatchling green turtle swimming performance.

PubMed

Booth, David T; Evans, Andrew

2011-01-01

For sea turtles nesting on beaches surrounded by coral reefs, the most important element of hatchling recruitment is escaping predation by fish as they swim across the fringing reef, and as a consequence hatchlings that minimize their exposure to fish predation by minimizing the time spent crossing the fringing reef have a greater chance of surviving the reef crossing. One way to decrease the time required to cross the fringing reef is to maximize swimming speed. We found that both water temperature and nest temperature influence swimming performance of hatchling green turtles, but in opposite directions. Warm water increases swimming ability, with hatchling turtles swimming in warm water having a faster stroke rate, while an increase in nest temperature decreases swimming ability with hatchlings from warm nests producing less thrust per stroke.

Angulated Dental Implants in Posterior Maxilla FEA and Experimental Verification.

PubMed

Hamed, Hamed A; Marzook, Hamdy A; Ghoneem, Nahed E; El-Anwar, Mohamed I

2018-02-15

This study aimed to evaluate the effect of different implant angulations in posterior maxilla on stress distribution by finite element analysis and verify its results experimentally. Two simplified models were prepared for an implant placed vertically and tilted 25° piercing the maxillary sinus. Geometric models' components were prepared by Autodesk Inventor then assembled in ANSYS for finite element analysis. The results of finite element analysis were verified against experimental trials results which were statistically analysed using student t-test (level of significance p < 0.05). Implant - abutment complex absorbed the load energy in case of vertical implant better than the case of angulated one. That was reflected on cortical bone stress, while both cases showed stress levels within the physiological limits. Comparing results between FEA and experiment trials showed full agreement. It was found that the tilted implant by 25° can be utilised in the posterior region maxilla for replacing maxillary first molar avoiding sinus penetration. The implant-bone interface and peri-implant bones received the highest Von Mises stress. Implant - bone interface with angulated implant received about 66% more stresses than the straight one.

Adaptive Meshing Techniques for Viscous Flow Calculations on Mixed Element Unstructured Meshes

NASA Technical Reports Server (NTRS)

Mavriplis, D. J.

1997-01-01

An adaptive refinement strategy based on hierarchical element subdivision is formulated and implemented for meshes containing arbitrary mixtures of tetrahendra, hexahendra, prisms and pyramids. Special attention is given to keeping memory overheads as low as possible. This procedure is coupled with an algebraic multigrid flow solver which operates on mixed-element meshes. Inviscid flows as well as viscous flows are computed an adaptively refined tetrahedral, hexahedral, and hybrid meshes. The efficiency of the method is demonstrated by generating an adapted hexahedral mesh containing 3 million vertices on a relatively inexpensive workstation.

Linear positioning laser calibration setup of CNC machine tools

NASA Astrophysics Data System (ADS)

Sui, Xiulin; Yang, Congjing

2002-10-01

The linear positioning laser calibration setup of CNC machine tools is capable of executing machine tool laser calibraiotn and backlash compensation. Using this setup, hole locations on CNC machien tools will be correct and machien tool geometry will be evaluated and adjusted. Machien tool laser calibration and backlash compensation is a simple and straightforward process. First the setup is to 'find' the stroke limits of the axis. Then the laser head is then brought into correct alignment. Second is to move the machine axis to the other extreme, the laser head is now aligned, using rotation and elevation adjustments. Finally the machine is moved to the start position and final alignment is verified. The stroke of the machine, and the machine compensation interval dictate the amount of data required for each axis. These factors determine the amount of time required for a through compensation of the linear positioning accuracy. The Laser Calibrator System monitors the material temperature and the air density; this takes into consideration machine thermal growth and laser beam frequency. This linear positioning laser calibration setup can be used on CNC machine tools, CNC lathes, horizontal centers and vertical machining centers.

Investigation of the effects of mirror therapy on the upper extremity functions of stroke patients using the manual function test.

PubMed

Kim, Hwanhee; Shim, Jemyung

2015-01-01

[Purpose] The purpose of this study was to investigate the effects of mirror therapy on the upper extremity functions of stroke patients. [Subjects] The subjects of this study were 14 hemiplegia patients (8 males, 6 females; 9 infarction, 5 hemorrhage; 8 right hemiplegia, 6 left hemiplegia) who voluntarily consented to participate in the study. [Methods] The Korean version of the manual function test (MFT) was used in this study. The test was performed in the following order: arm movement (4 items), grasp and pinch (2 items), and manipulation (2 items). The experiment was conducted with the subjects sitting in a chair. The mirror was vertically placed in the sagittal plane on the desk. The paretic hand was placed behind the mirror, and the non-paretic hand was placed in front of the mirror so that it was reflected in the mirror. In this position, the subjects completed activities repetitively according to the mirror therapy program over the course of four weeks. [Results] There were significant increases in the grasp-and-pinch score and manipulation score. [Conclusion] In conclusion, the grasp-and-pinch and manipulation functions were improved through mirror therapy.

REPETITIVE TASK PRACTICE: A CRITICAL REVIEW OF CONSTRAINT-INDUCED MOVEMENT THERAPY IN STROKE

PubMed Central

Wolf, Steven L.; Blanton, Sarah; Baer, Heather; Breshears, Jenifer; Butler, Andrew J.

2013-01-01

BACKGROUND Constraint-induced (CI) movement therapy (also called forced use by some investigators and clinicians) has gained increasing popularity as a treatment mode for restoring function in the upper extremities of patients with stroke. The purpose of this article is to review the concept of constraint-induced movement therapy and provide a critical analysis of the existing data. REVIEW SUMMARY The evidence to date offers encouragement for the application of this procedure for patients who have some movement recovery out of synergy. Success may be contingent on patient cooperation and intense repetitive use with applications of retraining through practice and shaping. The extent to which each of the latter elements influences the magnitude of recovery is still unclear. However, task novelty and challenge seem important to recovery of function. There are several methods used to map cortical changes after stroke. At this time, transcranial magnetic stimulation is the primary vehicle used to assess motor cortical reorganization after CI therapy in humans. CONCLUSIONS Accumulating data indicate that the size of a cortical area representative of a muscle does expand and its center of gravity does change with CI therapy. PMID:12801434

Lightweight two-stroke cycle aircraft diesel engine technology enablement program, volume 1

NASA Technical Reports Server (NTRS)

Freen, P. D.; Berenyi, S. G.; Brouwers, A. P.; Moynihan, M. E.

1985-01-01

An experimental Single Cylinder Test Engine Program is conducted to confirm the analytically projected performance of a two-stroke cycle diesel engine for aircraft applications. The test engine delivered 78kW indicated power from 1007cc displacement, operating at 3500 RPM on Schnuerle loop scavenged two-stroke cycle. Testing confirms the ability of a proposed 4-cylinder version of such an engine to reach the target power at altitude, in a highly turbocharged configuration. The experimental program defines all necessary parameters to permit design of a multicylinder engine for eventual flight applications; including injection system requirement, turbocharging, heat rejection, breathing, scavenging, and structural requirements. The multicylinder engine concept is configured to operate with an augmented turbocharger, but with no primary scavenge blower. The test program is oriented to provide a balanced turbocharger compressor to turbine power balance without an auxiliary scavenging system. Engine cylinder heat rejection to the ambient air has been significantly reduced and the minimum overall turbocharger efficiency required is within the range of commercially available turbochargers. Analytical studies and finite element modeling is made of insulated configurations of the engines - including both ceramic and metallic versions. A second generation test engine is designed based on current test results.

Stacked white OLED having separate red, green and blue sub-elements

DOEpatents

Forrest, Stephen; Qi, Xiangfei; Slootsky, Michael

2014-07-01

The present invention relates to efficient organic light emitting devices (OLEDs). The devices employ three emissive sub-elements, typically emitting red, green and blue, to sufficiently cover the visible spectrum. Thus, the devices may be white-emitting OLEDs, or WOLEDs. Each sub-element comprises at least one organic layer which is an emissive layer--i.e., the layer is capable of emitting light when a voltage is applied across the stacked device. The sub-elements are vertically stacked and are separated by charge generating layers. The charge-generating layers are layers that inject charge carriers into the adjacent layer(s) but do not have a direct external connection.

Assembling of Steel Angle Headframe of Multifunctional Purpose

NASA Astrophysics Data System (ADS)

Kassikhina, E. G.; Pershin, V. V.; Volkov, V. M.

2017-10-01

The article reviews new technical solution on equipment provision of vertical shaft utilizing steel headframe of multifunctional purpose. Practice of construction of coal and ore mines provides application of various designs for steel angle headframes which are divided into separate large assembly blocks and constructive elements during assembling operations. Design of these blocks and elements, their weight and dimensions effect the chose of the method of assembling on which economic and technological indicators, as well as duration of down-time, depend on during performance of construction operations in shaft. The technical solution on equipment provision for mine vertical shaft using headframe of multifunctional purpose will allow changing the management construction of vertical shaft. The proposed headframe combines the functions of sinking and operation that eliminates costs for assembling/dissembling of temporary headgear. The constructive design of the headgear allows application of the effective method of assembly and thus to provide improvement of the technical and economic indexes, and high calendar time rate of the shaft construction due to reduction of duration of works on equipment provision for the shaft and to refurbishment of the shaft in order to carry out horizontal mining.

Finite element analysis on preferable I-bar clasp shape.

PubMed

Sato, Y; Tsuga, K; Abe, Y; Asahara, S; Akagawa, Y

2001-05-01

An I-bar clasp is one of the most popular direct retainers for distal-extension removable partial dentures. However, no adequate information is available on preferable shape as determined by biomechanics. This study aimed (1) to investigate, by finite element analysis (FEA), the dimensions and stress of I-bar clasps having the same stiffness, and (2) to estimate a mechanically preferable clasp design. Three-dimensional FEA models of I-bar clasps were created with vertical and horizontal straight sections connected by a curved section characterized by six parameters: thickness of the clasp tip, width of the clasp tip, radius of the curvature, horizontal distance between the base and the vertical axis, vertical dimension between the tip and the horizontal axis, and taper (change of width per unit length along the axis). Stress was calculated with a concentrated load of 5 N applied 2 mm from the tip of the clasp in the buccal direction. A thinner and wider clasp having an taper of 0.020-0.023 and radius of curvature of 2.75-3.00 showed less stress. The results suggest that such a shape might be the preferable I-bar clasp shape as biomechanical viewpoint.

Physiological Effects of Early Incremental Mobilization of a Patient with Acute Intracerebral and Intraventricular Hemorrhage Requiring Dual External Ventricular Drainage.

PubMed

Kumble, Sowmya; Zink, Elizabeth K; Burch, Mackenzie; Deluzio, Sandra; Stevens, Robert D; Bahouth, Mona N

2017-08-01

Recent trials have challenged the notion that very early mobility benefits patients with acute stroke. It is unclear how cerebral autoregulatory impairments, prevalent in this population, could be affected by mobilization. The safety of mobilizing patients who have external ventricular drainage (EVD) devices for cerebrospinal fluid diversion and intracranial pressure (ICP) monitoring is another concern due to risk of device dislodgment and potential elevation in ICP. We report hemodynamic and ICP responses during progressive, device-assisted mobility interventions performed in a critically ill patient with intracerebral hemorrhage (ICH) requiring two EVDs. A 55-year-old man was admitted to the Neuroscience Critical Care Unit with an acute thalamic ICH and complex intraventricular hemorrhage requiring placement of two EVDs. Progressive mobilization was achieved using mobility technology devices. Range of motion exercises were performed initially, progressing to supine cycle ergometry followed by incremental verticalization using a tilt table. Physiological parameters were recorded before and after the interventions. All mobility interventions were completed without any adverse event or clinically detectable change in the patient's neurological state. Physiological parameters including hemodynamic variables and ICP remained within prescribed goals throughout. Progressive, device-assisted early mobilization was feasible and safe in this critically ill patient with hemorrhagic stroke when titrated by an interdisciplinary team of skilled healthcare professionals. Studies are needed to gain insight into the hemodynamic and neurophysiological responses associated with early mobility in acute stroke to identify subsets of patients who are most likely to benefit from this intervention.

[A complex study of the movement biomechanics in patients with post-stroke hemiparesis].

PubMed

Skvortsov, D V; Bulatova, M A; Kovrazhkina, E A; Suvorov, A Iu; Ivanova, G E; Skvortsova, V I

2012-01-01

The authors present results of a pilot study on biomechanics of non-cyclic movements of the human consequent verticalization in the ontogenesis of patients with post-stroke hemiparesis (10 patients in the acute stage of cerebral stroke) and 10 healthy volunteers without neurologic and orthopedic pathology. Some movements of therapeutic exercises Balance (a model of ontogenetic kinesitherapy) have been selected for the study. Cinematic parameters have been recorded using a system of motion 3D video analysis, a kinematic model was build in accordance to standard protocols. The skin (native and straightened) electromyogram (EMG) was recorded synchronously with kinematic data using 16-channel electromyography from the following pairs of muscles: mm. sternocleido-mastoideus, trapezius (горизонтальная порция), biceps brachii, triceps brachii, rectus femoris, adductor magnus. Major differences in the EMG picture between patients and controls were: 1) the EMG "monotony" with the involvement of multiple additional muscles in locomotions with the prevalence of the peculiar "tonic" muscle activity (low amplitudes without distinct peaks), stretching along the whole cycle of movement. In controls, EMG demonstrated variability and had mostly "phasic" character with distinct 1 or 2 peaks; 2) the asymmetry of EMG profile in symmetric movements. i.e. when performed simultaneously from the right and from the left sides. The latter feature may be considered as predictive because it was never found in healthy people. It allows to identify objectively weak muscles even in the absence of visible parethis during the routine neurological examination.

Talent identification and early development of elite water-polo players: a 2-year follow-up study.

PubMed

Falk, Bareket; Lidor, Ronnie; Lander, Yael; Lang, Benny

2004-04-01

The processes of talent detection and early development are critical in any sport programme. However, not much is known about the appropriate strategies to be implemented during these processes, and little scientific inquiry has been conducted in this area. The aim of this study was to identify variables of swimming, ball handling and physical ability, as well as game intelligence, which could assist in the selection process of young water-polo players. Twenty-four players aged 14-15 years underwent a battery of tests three times during a 2-year period, before selection to the junior national team. The tests included: freestyle swim for 50, 100, 200 and 400 m, 100-m breast-stroke, 100-m 'butterfly' (with breast-stroke leg motion), 50-m dribbling, throwing at the goal, throw for distance in the water, vertical 'jump' from the water, and evaluation of game intelligence by two coaches. A comparison of those players eventually selected to the team and those not selected demonstrated that, 2 years before selection, selected players were already superior on most of the swim tasks (with the exception of breast-stroke and 50-m freestyle), as well as dribbling and game intelligence. This superiority was maintained throughout the 2 years. Two-way tabulation revealed that, based on baseline scores, the prediction for 67% of the players was in agreement with the final selection to the junior national team. We recommend that fewer swim events be used in the process of selecting young water-polo players, and that greater emphasis should be placed on evaluation of game intelligence.

Influence of different abutment diameter of implants on the peri-implant stress in the crestal bone: A three-dimensional finite element analysis--In vitro study.

PubMed

Aradya, Anupama; Kumar, U Krishna; Chowdhary, Ramesh

2016-01-01

The study was designed to evaluate and compare stress distribution in transcortical section of bone with normal abutment and platform switched abutment under vertical and oblique forces in posterior mandible region. A three-dimensional finite element model was designed using ANSYS 13.0 software. The type of bone selection for the model was made of type II mandibular bone, having cortical bone thickness ranging from 0.595 mm to 1.515 mm with the crestal region measuring 1.5 mm surrounding dense trabecular bone. The implant will be modulated at 5 mm restorative platform and tapering down to 4.5 mm wide at the threads, 13 mm long with an abutment 3 mm in height. The models will be designed for two situations: (1) An implant with a 5 mm diameter abutment representing a standard platform in the posterior mandible region. (2) An implant with a 4.5 mm diameter abutment representing platform switching in the posterior mandible region. Force application was performed in both oblique and vertical conditions using 100 N as a representative masticatory force. For oblique loading, a force of 100 N was applied at 15° from the vertical axis. von Mises stress analysis was evaluated. The results of the study showed cortical stress in the conventional and platform switching model under oblique forces were 59.329 MPa and 39.952 MPa, respectively. Cortical stress in the conventional and platform switching model under vertical forces was 13.914 MPa and 12.793 MPa, respectively. Results from this study showed the platform switched abutment led to relative decrease in von Mises stress in transcortical section of bone compared to normal abutment under vertical and oblique forces in posterior mandible region.

Photovoltaic sheathing element with one or more tabs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keenihan, James R; Langmaid, Joseph A; Lopez, Leonardo C.

2017-02-07

The present invention is premised upon an assembly that includes at least a photovoltaic sheathing element capable of being affixed on a building structure. The shingle including at least a photovoltaic cell assembly, a body portion attached to one or more portions of the photovoltaic cell assembly. Wherein the body portion includes one or more top peripheral tabs each capable of fitting under one or more vertically adjoining devices.

Characteristics of lightning flashes generating sprites above thunderstorms

NASA Astrophysics Data System (ADS)

Soula, S.; Van Der Velde, O. A.; Montanya, J.; Fullekrug, M.; Mlynarczyk, J.

2016-12-01

Sprites are Transient Luminous Events (TLEs) consisting of streamer discharges, in response to a strong transient electrostatic field that exceeds the threshold for dielectric breakdown in the mesosphere. A large panel of sprite observations have been made with several low-light video cameras located in southern France, especially at Pic du Midi (2877 m) in the Pyrénées mountain range. The optical detection of these luminous events allow to determine some of their characteristics as the timing, the duration, the location, the size, the shape, the luminosity. Other parameters describing the storm and the lightning activity provided by different instruments are associated to the sprite observations to a better understanding of their conditions of production and their characteristic settings: (i) the sprites are essentially produced above the stratiform region of the Mesoscale Convective Systems during positive cloud-to-ground lightning flashes that produce large Charge Moment Change (CMC) and with a delay of as much shorter than the current is large. (ii) The long time delayed sprites are associated with continuing current and large CMC. (iii) The sprite elements can be shifted from the stroke location when their delay is long. (iv) Very luminous sprites can produce large current signatures visible in ELF radiation a few milliseconds (< 5 ms) after the positive strokes that generate them, but sometimes imbedded in that of the stroke pulse. (v) Several cases of "dancing sprites" show the successive light emissions reflect the timing and the location of the strokes of the lightning flashes that generate them.

Location and orientation of panel on the screen as a structural visual element to highlight text displayed

NASA Astrophysics Data System (ADS)

Léger, Laure; Chevalier, Aline

2017-07-01

Searching for information on the internet has become a daily activity. It is considered to be a complex cognitive activity that involves visual attention. Many studies have demonstrated that users' information search are affected both by the spatial configuration of words and the elements displayed on the screen: elements that are used to structure web pages. One of these elements, the web panel, contains information. Web panel is a rectangular area with a colored background that was used to highlighting content presented in this specific rectangular area. Our general hypothesis was that the presence of a panel on a web page would affect the structure of a word display, as a result, information search accuracy. We carried out an experiment in which we manipulated the presence vs. the absence of a panel, as well as its orientation on the screen (vertical vs. horizontal). Twenty participants were asked to answer questions while their eye movements were recorded. Results showed that the presence of a panel resulted in reduced accuracy and shorter response times. Panel orientation affected scanpaths, especially when they were orientated vertically. We discuss these findings and suggest ways in which this research could be developed further in future.

Measuring pictorial balance perception at first glance using Japanese calligraphy

PubMed Central

Gershoni, Sharon; Hochstein, Shaul

2011-01-01

According to art theory, pictorial balance acts to unify picture elements into a cohesive composition. For asymmetrical compositions, balancing elements is thought to be similar to balancing mechanical weights in a framework of symmetry axes. Assessment of preference for balance (APB), based on the symmetry-axes framework suggested in Arnheim R, 1974 Art and Visual Perception: A Psychology of the Creative Eye (Berkeley, CA: University of California Press), successfully matched subject balance ratings of images of geometrical shapes over unlimited viewing time. We now examine pictorial balance perception of Japanese calligraphy during first fixation, isolated from later cognitive processes, comparing APB measures with results from balance-rating and comparison tasks. Results show high between-task correlation, but low correlation with APB. We repeated the rating task, expanding the image set to include five rotations of each image, comparing balance perception of artist and novice participant groups. Rotation has no effect on APB balance computation but dramatically affects balance rating, especially for art experts. We analyze the variety of rotation effects and suggest that, rather than depending on element size and position relative to symmetry axes, first fixation balance processing derives from global processes such as grouping of lines and shapes, object recognition, preference for horizontal and vertical elements, closure, and completion, enhanced by vertical symmetry. PMID:23145242

Infrasound-array-element frequency response: in-situ measurement and modeling

NASA Astrophysics Data System (ADS)

Gabrielson, T.

2011-12-01

Most array elements at the infrasound stations of the International Monitoring System use some variant of a multiple-inlet pipe system for wind-noise suppression. These pipe systems have a significant impact on the overall frequency response of the element. The spatial distribution of acoustic inlets introduces a response dependence that is a function of frequency and of vertical and horizontal arrival angle; the system of inlets, pipes, and summing junctions further shapes that response as the signal is ducted to the transducer. In-situ measurements, using a co-located reference microphone, can determine the overall frequency response and diagnose problems with the system. As of July 2011, the in-situ frequency responses for 25 individual elements at 6 operational stations (I10, I53, I55, I56, I57, and I99) have been measured. In support of these measurements, a fully thermo-viscous model for the acoustics of these multiple-inlet pipe systems has been developed. In addition to measurements at operational stations, comparative analyses have been done on experimental systems: a multiple-inlet radial-pipe system with varying inlet hole size; a one-quarter scale model of a 70-meter rosette system; and vertical directionality of a small rosette system using aircraft flyovers. [Funded by the US Army Space and Missile Defense Command

Geochemistry of Thorium and Uranium in Soils of the Southern Urals

NASA Astrophysics Data System (ADS)

Asylbaev, I. G.; Khabirov, I. K.; Gabbasova, I. M.; Rafikov, B. V.; Lukmanov, N. A.

2017-12-01

Specific features of the horizontal and vertical distribution of uranium and thorium in soils and parent materials of the Southern Urals within the Bashkortostan Republic have been studied with the use of mass spectrometry with inductively coupled plasma. The dependence of distribution patterns of these elements on the local environmental conditions is shown. A scale for soil evaluation according to the concentrations of uranium and thorium (mg/kg) is suggested: the low level, up to 3; medium, up to 9; high, up to 15; and very high, above 15 mg/kg. On the basis of to this scale, the ecological state of the soils is evaluated, and the schematic geochemical map of the region is compiled. The territory of Bashkortostan is subdivided into two parts according to the contents of radioactive elements in soils: the western part with distinct accumulation of uranium and the eastern part with predominant thorium accumulation. This finding supports the charriage (thrust fault) nature of the fault zone of the Southern Urals. The vertical distribution patterns of uranium and thorium in soils of the region are of the same character. The dependence between the contents of these two elements and rare-earth elements has been established. The results of this study are applied for assessing the ecological state of soils in the region.

Four-dimensional modeling of recent vertical movements in the area of the southern California uplift

USGS Publications Warehouse

Vanicek, Petr; Elliot, Michael R.; Castle, Robert O.

1979-01-01

This paper describes an analytical technique that utilizes scattered geodetic relevelings and tide-gauge records to portray Recent vertical crustal movements that may have been characterized by spasmodic changes in velocity. The technique is based on the fitting of a time-varying algebraic surface of prescribed degree to the geodetic data treated as tilt elements and to tide-gauge readings treated as point movements. Desired variations in time can be selected as any combination of powers of vertical movement velocity and episodic events. The state of the modeled vertical displacement can be shown for any number of dates for visual display. Statistical confidence limits of the modeled displacements, derived from the density of measurements in both space and time, line length, and accuracy of input data, are also provided. The capabilities of the technique are demonstrated on selected data from the region of the southern California uplift. 

Determination of crash test pulses and their application to aircraft seat analysis

NASA Technical Reports Server (NTRS)

Alfaro-Bou, E.; Williams, M. S.; Fasanella, E. L.

1981-01-01

Deceleration time histories (crash pulses) from a series of twelve light aircraft crash tests conducted at NASA Langley Research Center (LaRC) were analyzed to provide data for seat and airframe design for crashworthiness. Two vertical drop tests at 12.8 m/s (42 ft/s) and 36 G peak deceleration (simulating one of the vertical light aircraft crash pulses) were made using an energy absorbing light aircraft seat prototype. Vertical pelvis acceleration measured in a 50 percentile dummy in the energy absorbing seat were found to be 45% lower than those obtained from the same dummy in a typical light aircraft seat. A hybrid mathematical seat-occupant model was developed using the DYCAST nonlinear finite element computer code and was used to analyze a vertical drop test of the energy absorbing seat. Seat and occupant accelerations predicted by the DYCAST model compared quite favorably with experimental values.

Characterization of Canopy Layering in Forested Ecosystems Using Full Waveform Lidar

NASA Technical Reports Server (NTRS)

Whitehurst, Amanda S.; Swatantran, Anu; Blair, J. Bryan; Hofton, Michelle A.; Dubayah, Ralph

2013-01-01

Canopy structure, the vertical distribution of canopy material, is an important element of forest ecosystem dynamics and habitat preference. Although vertical stratification, or "canopy layering," is a basic characterization of canopy structure for research and forest management, it is difficult to quantify at landscape scales. In this paper we describe canopy structure and develop methodologies to map forest vertical stratification in a mixed temperate forest using full-waveform lidar. Two definitions-one categorical and one continuous-are used to map canopy layering over Hubbard Brook Experimental Forest, New Hampshire with lidar data collected in 2009 by NASA's Laser Vegetation Imaging Sensor (LVIS). The two resulting canopy layering datasets describe variation of canopy layering throughout the forest and show that layering varies with terrain elevation and canopy height. This information should provide increased understanding of vertical structure variability and aid habitat characterization and other forest management activities.

Legacy Clinical Data from the Epo TBI Trial

DTIC Science & Technology

2015-10-01

Anemia in Traumatic Brain Injury (TBI)” which we will share with other investigators through the Federal Interagency Traumatic Brain Injury (FITBIR... Informatics System. This trial was funded by National Institute of Neurological Disorders and Stroke (NINDS) grant #P01-NS38660. The study began...Data Elements (CDEs) for TBI, and therefore requires work to convert the data to the format required by FITBIR. 2. KEYWORDS: Traumatic brain

Finite element method analysis of cold forging for deformation and densification of Mo alloyed sintered steel

NASA Astrophysics Data System (ADS)

Kamakoshi, Y.; Nishida, S.; Kanbe, K.; Shohji, I.

2017-10-01

In recent years, powder metallurgy (P/M) materials have been expected to be applied to automobile products. Then, not only high cost performance but also more strength, wear resistance, long-life and so on are required for P/M materials. As an improvement method of mechanical properties of P/M materials, a densification is expected to be one of effective processes. In this study, to examine behaviours of the densification of Mo-alloyed sintered steel in a cold-forging process, finite element method (FEM) analysis was performed. Firstly, a columnar specimen was cut out from the inner part of a sintered specimen and a load-stroke diagram was obtained by the compression test. 2D FEM analysis was performed using the obtained load-stroke diagram. To correct the errors of stress between the porous mode and the rigid-elastic mode of analysis software, the analysis of a polynominal approximation was performed. As a result, the modified true stress-true strain diagram was obtained for the sintered steel with the densification. Afterwards, 3D FEM analysis of backward extrusion was carried out using the modified true stress-true strain diagram. It was confirmed that both the shape and density of the sintered steel analyzed by new FEM analysis that we suggest correspond well with experimental ones.

Development of blood extraction system for health monitoring system

NASA Astrophysics Data System (ADS)

Tsuchiya, Kazuyoshi; Nakanishi, Naoyuki; Nakamachi, Eiji

2004-03-01

The purpose of this research is to develop the compact human blood sampling device applied for a health monitoring system(HMS), which is called "Mobile Hospital". The HMS consists of (1) a micro electrical pumping system for blood extraction, (2) a bio-sensor to detect and evaluate an amount of Glucose, Cholesterol and Urea in extracted blood, by using enzyme such as Glucoseoxidase (GOD), Cholesteroloxidase and Urease. The mechanical design elements of the device are bio-compatible microneedle, indentation unit using a shape memory alloy(SMA) actuator and pumping unit using a piezoelectric microactuator. The design concept is the biomimetic micromachine of female mosquito"s blood sampling mechanism. The performances of the main mechanical elements such as indentation force of the microneedle, actual stroke of the indentation unit using a SMA actuator and liquid sampling ability of the pumping unit using PZT piezoelectric microactuator were measured. The 3 mm stroke of the indentation load generated by SMA actuator was 0.8mN. The amount of imitation blood extracted by using bimorph PZT actuators was about 0.5 microliters for 10 sec. A 60-micrometer outer diameter and 25-micrometer inner diameter Titanium microneedle, which size is same as female mosquito"s labium, was produced by sputter deposition.

Terrain-driven unstructured mesh development through semi-automatic vertical feature extraction

NASA Astrophysics Data System (ADS)

Bilskie, Matthew V.; Coggin, David; Hagen, Scott C.; Medeiros, Stephen C.

2015-12-01

A semi-automated vertical feature terrain extraction algorithm is described and applied to a two-dimensional, depth-integrated, shallow water equation inundation model. The extracted features describe what are commonly sub-mesh scale elevation details (ridge and valleys), which may be ignored in standard practice because adequate mesh resolution cannot be afforded. The extraction algorithm is semi-automated, requires minimal human intervention, and is reproducible. A lidar-derived digital elevation model (DEM) of coastal Mississippi and Alabama serves as the source data for the vertical feature extraction. Unstructured mesh nodes and element edges are aligned to the vertical features and an interpolation algorithm aimed at minimizing topographic elevation error assigns elevations to mesh nodes via the DEM. The end result is a mesh that accurately represents the bare earth surface as derived from lidar with element resolution in the floodplain ranging from 15 m to 200 m. To examine the influence of the inclusion of vertical features on overland flooding, two additional meshes were developed, one without crest elevations of the features and another with vertical features withheld. All three meshes were incorporated into a SWAN+ADCIRC model simulation of Hurricane Katrina. Each of the three models resulted in similar validation statistics when compared to observed time-series water levels at gages and post-storm collected high water marks. Simulated water level peaks yielded an R2 of 0.97 and upper and lower 95% confidence interval of ∼ ± 0.60 m. From the validation at the gages and HWM locations, it was not clear which of the three model experiments performed best in terms of accuracy. Examination of inundation extent among the three model results were compared to debris lines derived from NOAA post-event aerial imagery, and the mesh including vertical features showed higher accuracy. The comparison of model results to debris lines demonstrates that additional validation techniques are necessary for state-of-the-art flood inundation models. In addition, the semi-automated, unstructured mesh generation process presented herein increases the overall accuracy of simulated storm surge across the floodplain without reliance on hand digitization or sacrificing computational cost.

The schemes and methods for producing of the visual security features used in the color hologram stereography

NASA Astrophysics Data System (ADS)

Lushnikov, D. S.; Zherdev, A. Y.; Odinokov, S. B.; Markin, V. V.; Smirnov, A. V.

2017-05-01

Visual security elements used in color holographic stereograms - three-dimensional colored security holograms - and methods their production is describes in this article. These visual security elements include color micro text, color-hidden image, the horizontal and vertical flip - flop effects by change color and image. The article also presents variants of optical systems that allow record the visual security elements as part of the holographic stereograms. The methods for solving of the optical problems arising in the recording visual security elements are presented. Also noted perception features of visual security elements for verification of security holograms by using these elements. The work was partially funded under the Agreement with the RF Ministry of Education and Science № 14.577.21.0197, grant RFMEFI57715X0197.

Progress in neuro-otology research in the last year.

PubMed

Tarnutzer, Alexander A; Straumann, Dominik

2012-11-01

Herein, we summarize articles in the field of neuro-otology published in the Journal of Neurology over the last year. Topics included acute and chronic vertigo as well as auditory and ocular motor disorders. Characteristic lesion locations in Pusher syndrome are reported and the usefulness of bedside ocular motor tests in vertebrobasilar stroke is revisited. Probing the vestibular system and its value in predicting the outcome in vegetative state is discussed. Several articles address new diagnostic and therapeutic approaches in different disorders associated with chronic vestibular, auditory or gait deficits. In a series of case reports, we focus on different eye movement disorders in the vertical plane, which are often difficult to assess.

Realistic kinetic loading of the jaw system during single chewing cycles: a finite element study.

PubMed

Martinez Choy, S E; Lenz, J; Schweizerhof, K; Schmitter, M; Schindler, H J

2017-05-01

Although knowledge of short-range kinetic interactions between antagonistic teeth during mastication is of essential importance for ensuring interference-free fixed dental reconstructions, little information is available. In this study, the forces on and displacements of the teeth during kinetic molar biting simulating the power stroke of a chewing cycle were investigated by use of a finite-element model that included all the essential components of the human masticatory system, including an elastic food bolus. We hypothesised that the model can approximate the loading characteristics of the dentition found in previous experimental studies. The simulation was a transient analysis, that is, it considered the dynamic behaviour of the jaw. In particular, the reaction forces on the teeth and joints arose from contact, rather than nodal forces or constraints. To compute displacements of the teeth, the periodontal ligament (PDL) was modelled by use of an Ogden material model calibrated on the basis of results obtained in previous experiments. During the initial holding phase of the power stroke, bite forces were aligned with the roots of the molars until substantial deformation of the bolus occurred. The forces tilted the molars in the bucco-lingual and mesio-distal directions, but as the intrusive force increased the teeth returned to their initial configuration. The Ogden material model used for the PDL enabled accurate prediction of the displacements observed in experimental tests. In conclusion, the comprehensive kinetic finite element model reproduced the kinematic and loading characteristics of previous experimental investigations. © 2017 John Wiley & Sons Ltd.

Hydraulic Fracture Growth in a Layered Formation based on Fracturing Experiments and Discrete Element Modeling

NASA Astrophysics Data System (ADS)

Yushi, Zou; Xinfang, Ma; Tong, Zhou; Ning, Li; Ming, Chen; Sihai, Li; Yinuo, Zhang; Han, Li

2017-09-01

Hydraulic fracture (HF) height containment tends to occur in layered formations, and it significantly influences the entire HF geometry or the stimulated reservoir volume. This study aims to explore the influence of preexisting bedding planes (BPs) on the HF height growth in layered formations. Laboratory fracturing experiments were performed to confirm the occurrence of HF height containment in natural shale that contains multiple weak and high-permeability BPs under triaxial stresses. Numerical simulations were then conducted to further illustrate the manner in which vertical stress, BP permeability, BP density(or spacing), pump rate, and fluid viscosity control HF height growth using a 3D discrete element method-based fracturing model. In this model, the rock matrix was considered transversely isotropic and multiple BPs can be explicitly represented. Experimental and numerical results show that the vertically growing HF tends to be limited by multi-high-permeability BPs, even under higher vertical stress. When the vertically growing HF intersects with the multi-high-permeability BPs, the injection pressure will be sharply reduced. If a low pumping rate or a low-viscosity fluid is used, the excess fracturing fluid leak-off into the BPs obviously decreases the rate of pressure build up, which will then limit the growth of HF. Otherwise, a higher pumping rate and/or a higher viscosity will reduce the leak-off time and fluid volume, but increase the injection pressure to drive the HF to grow and to penetrate through the BPs.

Vertical visual features have a strong influence on cuttlefish camouflage.

PubMed

Ulmer, K M; Buresch, K C; Kossodo, M M; Mäthger, L M; Siemann, L A; Hanlon, R T

2013-04-01

Cuttlefish and other cephalopods use visual cues from their surroundings to adaptively change their body pattern for camouflage. Numerous previous experiments have demonstrated the influence of two-dimensional (2D) substrates (e.g., sand and gravel habitats) on camouflage, yet many marine habitats have varied three-dimensional (3D) structures among which cuttlefish camouflage from predators, including benthic predators that view cuttlefish horizontally against such 3D backgrounds. We conducted laboratory experiments, using Sepia officinalis, to test the relative influence of horizontal versus vertical visual cues on cuttlefish camouflage: 2D patterns on benthic substrates were tested versus 2D wall patterns and 3D objects with patterns. Specifically, we investigated the influence of (i) quantity and (ii) placement of high-contrast elements on a 3D object or a 2D wall, as well as (iii) the diameter and (iv) number of 3D objects with high-contrast elements on cuttlefish body pattern expression. Additionally, we tested the influence of high-contrast visual stimuli covering the entire 2D benthic substrate versus the entire 2D wall. In all experiments, visual cues presented in the vertical plane evoked the strongest body pattern response in cuttlefish. These experiments support field observations that, in some marine habitats, cuttlefish will respond to vertically oriented background features even when the preponderance of visual information in their field of view seems to be from the 2D surrounding substrate. Such choices highlight the selective decision-making that occurs in cephalopods with their adaptive camouflage capability.

Vertical structure use by the Stout Iguana (Cyclura pinguis) on Guana Island, BVI

USGS Publications Warehouse

Cheek, Christopher A.; Hlavaty, Shay; Perkins, Rebecca N.; Peyton, Mark A.; Ryan, Caitlin N.; Zavaleta, Jennifer C.; Boal, Clint W.; Perry, Gad

2013-01-01

The Stout Iguana (Cyclura pinguis) is a critically endangered species endemic to the Puerto Rico Bank and currently restricted to the British Virgin Islands (BVI). Our study on Guana Island, BVI, focused on vertical structure use. Based on previous incidental observations, we hypothesized that Stout Iguanas use vertical structures and that adults and juveniles use such structures differently. In October 2011, we documented movement and vertical structure use by adult (n = 4) and juvenile (n = 11) iguanas with tracking bobbins. We recorded structure types used, heights attained on structures, distances between structures, and structure sizes. We found that Stout Iguanas used vertical structure more than previously documented. Trees comprised a significantly greater (P < 0.001) proportion of structures used by juveniles than by adults, whereas rocks comprised the greatest proportion of structures used by adults. In addition to differential structure use, juveniles climbed significantly higher (2.4 vs. 0.9 m on average; P < 0.001) than adults. We found no difference in the diameter or distance between structures used by adults and juveniles. Our results suggest that vertical structure use may be an important habitat element for free-ranging juvenile Stout Iguanas. Habitat management that provides vertical structure may be advantageous for the conservation of this species.

Microfabricated structures with electrical isolation and interconnections

NASA Technical Reports Server (NTRS)

Clark, William A. (Inventor); Juneau, Thor N. (Inventor); Roessig, Allen W. (Inventor); Lemkin, Mark A. (Inventor)

2001-01-01

The invention is directed to a microfabricated device. The device includes a substrate that is etched to define mechanical structures at least some of which are anchored laterally to the remainder of the substrate. Electrical isolation at points where mechanical structures are attached to the substrate is provided by filled isolation trenches. Filled trenches may also be used to electrically isolate structure elements from each other at points where mechanical attachment of structure elements is desired. The performance of microelectromechanical devices is improved by 1) having a high-aspect-ratio between vertical and lateral dimensions of the mechanical elements, 2) integrating electronics on the same substrate as the mechanical elements, 3) good electrical isolation among mechanical elements and circuits except where electrical interconnection is desired.

FUEL ELEMENT FOR NUCLEAR REACTORS

DOEpatents

Dickson, J.J.

1963-09-24

A method is described whereby fuel tubes or pins are cut, loaded with fuel pellets and a heat transfer medium, sealed at each end with slotted fittings, and assembled into a rectangular tube bundle to form a fuel element. The tubes comprising the fuel element are laterally connected between their ends by clips and tabs to form a linear group of spaced parallel tubes, which receive their vertical support by resting on a grid. The advantages of this method are that it permits elimination of structural material (e.g., fuel-element cans) within the reactor core, and removal of at least one fuel pin from an element and replacement thereof so that a burnable poison may be utilized during the core lifetime. (AEC)

Kinematic and diabatic vertical velocity climatologies from a chemistry climate model

NASA Astrophysics Data System (ADS)

Marinke Hoppe, Charlotte; Ploeger, Felix; Konopka, Paul; Müller, Rolf

2016-05-01

The representation of vertical velocity in chemistry climate models is a key element for the representation of the large-scale Brewer-Dobson circulation in the stratosphere. Here, we diagnose and compare the kinematic and diabatic vertical velocities in the ECHAM/Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) model. The calculation of kinematic vertical velocity is based on the continuity equation, whereas diabatic vertical velocity is computed using diabatic heating rates. Annual and monthly zonal mean climatologies of vertical velocity from a 10-year simulation are provided for both kinematic and diabatic vertical velocity representations. In general, both vertical velocity patterns show the main features of the stratospheric circulation, namely, upwelling at low latitudes and downwelling at high latitudes. The main difference in the vertical velocity pattern is a more uniform structure for diabatic and a noisier structure for kinematic vertical velocity. Diabatic vertical velocities show higher absolute values both in the upwelling branch in the inner tropics and in the downwelling regions in the polar vortices. Further, there is a latitudinal shift of the tropical upwelling branch in boreal summer between the two vertical velocity representations with the tropical upwelling region in the diabatic representation shifted southward compared to the kinematic case. Furthermore, we present mean age of air climatologies from two transport schemes in EMAC using these different vertical velocities and analyze the impact of residual circulation and mixing processes on the age of air. The age of air distributions show a hemispheric difference pattern in the stratosphere with younger air in the Southern Hemisphere and older air in the Northern Hemisphere using the transport scheme with diabatic vertical velocities. Further, the age of air climatology from the transport scheme using diabatic vertical velocities shows a younger mean age of air in the inner tropical upwelling branch and an older mean age in the extratropical tropopause region.

Reusable EGaIn-Injected Substrate-Integrated-Waveguide Resonator for Wireless Sensor Applications

PubMed Central

Memon, Muhammad Usman; Lim, Sungjoon

2015-01-01

The proposed structure in this research is constructed on substrate integrated waveguide (SIW) technology and has a mechanism that produces 16 different and distinct resonant frequencies between 2.45 and 3.05 GHz by perturbing a fundamental TE10 mode. It is a unique method for producing multiple resonances in a radio frequency planar structure without any extra circuitry or passive elements is developed. The proposed SIW structure has four vertical fluidic holes (channels); injecting eutectic gallium indium (EGaIn), also known commonly as liquid metal (LM), into these vertical channels produces different resonant frequencies. Either a channel is empty, or it is filled with LM. In total, the combination of different frequencies produced from four vertical channels is 16. PMID:26569257

Vertical integration of medical education: Riverland experience, South Australia.

PubMed

Rosenthal, D R; Worley, P S; Mugford, B; Stagg, P

2004-01-01

Vertical integration of medical education is currently a prominent international topic, resulting from recent strategic initiatives to improve medical education and service delivery in areas of poorly met medical need. In this article, vertical integration of medical education is defined as 'a grouping of curricular content and delivery mechanisms, traversing the traditional boundaries of undergraduate, postgraduate and continuing medical education, with the intent of enhancing the transfer of knowledge and skills between those involved in the learning-teaching process'. Educators closely involved with vertically integrated teaching in the Riverland of South Australia present an analytical description of the educational dynamics of this system. From this analysis, five elements are identified which underpin the process of successful vertical integration: (1) raised educational stakes; (2) local ownership; (3) broad university role; (4) longer attachments; and (5) shared workforce vision. Given the benefits to the Riverland medical education programs described in this paper, it is not surprising that vertical integration of medical education is a popular goal in many rural regions throughout the world. Although different contexts will result in different functional arrangements, it could be argued that the five principles outlined in this article can be applied in any region.

Investigation of best practices for maintenance of concrete bridge railings.

DOT National Transportation Integrated Search

2015-01-01

Biodeterioration on concrete surfaces of vertical elements of bridges represents a serious challenge to : the highway infrastructure in Louisiana. This report aims to document the causes of biodeterioration of : concrete surfaces and to document curr...

The use of a laser ceilometer for sky condition determination

NASA Astrophysics Data System (ADS)

Nadolski, Vickie L.; Bradley, James T.

The use of a laser ceilometer for determining sky condition is presented, with emphasis on the operation of the ceilometer, the sky-condition-reporting algorithm, and how the laser ceilometer and the sky-condition algorithm are used to give a report suitable for aircraft operations and meteorological application. The sampling and processing features of the Vaisala ceilometer produced a detailed and accurate cloud base 'signature' by taking 254 measurement samples of the energy scattered back from a single laser pulse as the pulse traveled from the surface to 12,000 ft. The transmit time from the projection of the laser pulse to its backscattering from a cloud element and subsequent return to a collocated receiver is measured and a cloud height element computed. Attention is given to the development of a vertical visibility concept and of a vertical-visibility algorithm, as well as the strengths and limitations of the sky condition report.

Modulated microwave microscopy and probes used therewith

DOEpatents

Lai, Keji; Kelly, Michael; Shen, Zhi-Xun

2012-09-11

A microwave microscope including a probe tip electrode vertically positionable over a sample and projecting downwardly from the end of a cantilever. A transmission line connecting the tip electrode to the electronic control system extends along the cantilever and is separated from a ground plane at the bottom of the cantilever by a dielectric layer. The probe tip may be vertically tapped near or at the sample surface at a low frequency and the microwave signal reflected from the tip/sample interaction is demodulated at the low frequency. Alternatively, a low-frequency electrical signal is also a non-linear electrical element associated with the probe tip to non-linearly interact with the applied microwave signal and the reflected non-linear microwave signal is detected at the low frequency. The non-linear element may be semiconductor junction formed near the apex of the probe tip or be an FET formed at the base of a semiconducting tip.

The influence of atmospheric particles on the elemental content of vegetables in urban gardens of Sao Paulo, Brazil.

PubMed

Amato-Lourenco, Luís Fernando; Moreira, Tiana Carla Lopes; de Oliveira Souza, Vanessa Cristina; Barbosa, Fernando; Saiki, Mitiko; Saldiva, Paulo Hilário Nascimento; Mauad, Thais

2016-09-01

Although urban horticulture provides multiple benefits to society, the extent to which these vegetables are contaminated by the absorption of chemical elements derived from atmospheric deposition is unclear. This study was designed to evaluate the influence of air pollution on leafy vegetables in community gardens of Sao Paulo, Brazil. Vegetable seedlings of Brassica oleracea var. acephala (collard greens) and Spinacia oleracea (spinach) obtained in a non-polluted rural area and growing in vessels containing standard uncontaminated soil were exposed for three consecutive periods of 30, 60 and 90 days in 10 community gardens in Sao Paulo and in one control site. The concentrations of 17 chemical elements (traffic-related elements and those essential to plant biology) were quantified by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Tillandsia usneoides L. specimens were used as air plant biomonitors. The concentrations of As, Cd, Cr and Pb found in vegetables were compared to the recommended values for consumption. Principal Component Analysis (PCA) was used to cluster the elemental concentrations, and Generalized Linear Models (GLMs) were employed to evaluate the association of the factor scores from each PCA component with variables such as local weather, traffic burden and vertical barriers adjacent to the gardens. We found significant differences in the elemental concentrations of the vegetables in the different community gardens. These differences were related to the overall traffic burden, vertical obstacles and local weather. The Pb and Cd concentrations in both vegetables exceeded the limit values for consumption after 60 days of exposure. A strong correlation was observed between the concentration of traffic-related elements in vegetables and in Tillandsia usneoides L. An exposure response was observed between traffic burden and traffic-derived particles absorbed in the vegetables. Traffic-derived air pollution directly influences the absorption of chemical elements in leafy vegetables, and the levels of these elements may exceed the recommended values for consumption. Copyright © 2016 Elsevier Ltd. All rights reserved.

Static and dynamic characteristics of a piezoceramic strut

NASA Technical Reports Server (NTRS)

Pokines, Brett J.; Belvin, W. Keith; Inman, Daniel J.

1993-01-01

The experimental study of a piezoceramic active truss is presented. This active strut is unique in that the piezoceramic configurations allow the stroke length of the strut not to be dependent on the piezoceramic material's expansion range but on the deflection range of the piezoceramic bender segment. A finite element model of a piezoceramic strut segment was constructed. Piezoceramic actuation was simulated using thermally induced strains. This model yielded information on the stiffness and force range of a bender element. The static and dynamic properties of the strut were identified experimentally. Feedback control was used to vary the stiffness of the strut. The experimentally verified model was used to explore implementation possibilities of the strut.

Investigating Summer Thermal Stratification in Lake Ontario

NASA Astrophysics Data System (ADS)

James, S. C.; Arifin, R. R.; Craig, P. M.; Hamlet, A. F.

2017-12-01

Seasonal temperature variations establish strong vertical density gradients (thermoclines) between the epilimnion and hypolimnion. Accurate simulation of vertical mixing and seasonal stratification of large lakes is a crucial element of the thermodynamic coupling between lakes and the atmosphere in integrated models. Time-varying thermal stratification patterns can be accurately simulated with the versatile Environmental Fluid Dynamics Code (EFDC). Lake Ontario bathymetry was interpolated onto a 2-km-resolution curvilinear grid with vertical layering using a new approach in EFDC+, the so-called "sigma-zed" coordinate system which allows the number of vertical layers to be varied based on water depth. Inflow from the Niagara River and outflow to the St. Lawrence River in conjunction with hourly meteorological data from seven local weather stations plus three-hourly data from the North American Regional Reanalysis govern the hydrodynamic and thermodynamic responses of the Lake. EFDC+'s evaporation algorithm was updated to more accurately simulate net surface heat fluxes. A new vertical mixing scheme from Vinçon-Leite that implements different eddy diffusivity formulations above and below the thermocline was compared to results from the original Mellor-Yamada vertical mixing scheme. The model was calibrated by adjusting solar-radiation absorption coefficients in addition to background horizontal and vertical mixing parameters. Model skill was evaluated by comparing measured and simulated vertical temperature profiles at shallow (20 m) and deep (180 m) locations on the Lake. These model improvements, especially the new sigma-zed vertical discretization, accurately capture thermal-stratification patterns with low root-mean-squared errors when using the Vinçon-Leite vertical mixing scheme.

Analysis of Square Cup Deep-Drawing Test of Pure Titanium

NASA Astrophysics Data System (ADS)

Ogawa, Takaki; Ma, Ninshu; Ueyama, Minoru; Harada, Yasunori

2016-08-01

The prediction of formability of titunium is more difficult than steels since its strong anisotropy. If computer simulation can estimate the formability of titanium, we can select the optimal forming conditions. The purpose of this study was to acquire knowledge for the formability prediction by the computer simulation of the square cup deep-drawing of pure titanium. In this paper, the results of FEM analsis of pure titanium were compared with the experimental results to examine the analysis validity. We analyzed the formability of deepdrawing square cup of titanium by the FEM using solid elements. Compared the analysis results with the experimental results such as the forming shape, the punch load, and the thickness, the validity was confirmed. Further, through analyzing the change of the thickness around the forming corner, it was confirmed that the thickness increased to its maximum value during forming process at the stroke of 35mm more than the maximum stroke.

Combining Upper Limb Robotic Rehabilitation with Other Therapeutic Approaches after Stroke: Current Status, Rationale, and Challenges

PubMed Central

Grosmaire, Anne Gaëlle; Battini, Elena

2017-01-01

A better understanding of the neural substrates that underlie motor recovery after stroke has led to the development of innovative rehabilitation strategies and tools that incorporate key elements of motor skill relearning, that is, intensive motor training involving goal-oriented repeated movements. Robotic devices for the upper limb are increasingly used in rehabilitation. Studies have demonstrated the effectiveness of these devices in reducing motor impairments, but less so for the improvement of upper limb function. Other studies have begun to investigate the benefits of combined approaches that target muscle function (functional electrical stimulation and botulinum toxin injections), modulate neural activity (noninvasive brain stimulation), and enhance motivation (virtual reality) in an attempt to potentialize the benefits of robot-mediated training. The aim of this paper is to overview the current status of such combined treatments and to analyze the rationale behind them. PMID:29057269

Weather types and strokes in the Augsburg region (Southern Germany)

NASA Astrophysics Data System (ADS)

Beck, Christoph; Ertl, Michael; Giemsa, Esther; Jacobeit, Jucundus; Naumann, Markus; Seubert, Stefanie

2017-04-01

Strokes are one of the leading causes of morbidity and mortality worldwide and the main reason for longterm care dependency in Germany. Concerning the economical impact on patients and healthcare systems it is of particular importance to prevent this disease as well as to improve the outcome of the affected persons. Beside the primary well-known risk factors like hypertension, cigarette smoking, physical inactivity and others, also weather seems to have pronounced influence on the occurrence and frequency of strokes. Previous studies most often focused on effects of singular meteorological variables like ambient air temperature, air pressure or humidity. An advanced approach is to link the entire suite of daily weather elements classified to air mass- or weather types to cerebrovascular morbidity or mortality. In a joint pilot study bringing together climatologists, environmental scientists and physicians from the University of Augsburg and the clinical centre Augsburg, we analysed relationships between singular meteorological parameters as well as combined weather effects (e.g. weather types) and strokes in the urban area of Augsburg and the surrounding rural region. A total of 17.501 stroke admissions to Neurological Clinic and Clinical Neurophysiology at Klinikum Augsburg between 2006 and 2015 are classified to either "ischaemic" (16.354) or "haemorrhagic" (1.147) subtype according to etiology (based on the International Classification of Diseases - 10th Revision). Spearman correlations between daily frequencies of ischaemic and haemorrhagic strokes and singular atmospheric parameters (T, Tmin, Tmax, air pressure, humidity etc.) measured at the DWD (German weather service) meteorological station at Augsburg Muehlhausen are rather low. However, higher correlations are achieved when considering sub-samples of "homogenous weather conditions" derived from synoptic circulation classifications: e.g. within almost all of 10 types arising from a classification of central European mean sea level pressure fields into "Großwettertypes" (Beck 2000) the relationships between meteorological variables and stroke frequencies are increasing. Mainly temperature variables (Tmin, Tmax, Tmean) appear to be important particularly in winter and summer. Moreover distinct correlations of similar magnitude are obtained with other variables like wind speed or precipitation for specific weather types (e.g. westerly type). In how far these initial findings do really point to additional health impacts beyond temperature effects is subject of ongoing work.

Kinematics of a vertical axis wind turbine with a variable pitch angle

NASA Astrophysics Data System (ADS)

Jakubowski, Mateusz; Starosta, Roman; Fritzkowski, Pawel

2018-01-01

A computational model for the kinematics of a vertical axis wind turbine (VAWT) is presented. A H-type rotor turbine with a controlled pitch angle is considered. The aim of this solution is to improve the VAWT productivity. The discussed method is related to a narrow computational branch based on the Blade Element Momentum theory (BEM theory). The paper can be regarded as a theoretical basis and an introduction to further studies with the application of BEM. The obtained torque values show the main advantage of using the variable pitch angle.

Investigation of vertical cavity surface emitting laser dynamics for neuromorphic photonic systems

NASA Astrophysics Data System (ADS)

Hurtado, A.; Schires, K.; Henning, I. D.; Adams, M. J.

2012-03-01

We report an approach based upon vertical cavity surface emitting lasers (VCSELs) to reproduce optically different behaviors exhibited by biological neurons but on a much faster timescale. The technique proposed is based on the polarization switching and nonlinear dynamics induced in a single VCSEL under polarized optical injection. The particular attributes of VCSELs and the simple experimental configuration used in this work offer prospects of fast, reconfigurable processing elements with excellent fan-out and scaling potentials for use in future computational paradigms and artificial neural networks.

Culvert roughness elements for native Utah fish passage : phase I.

DOT National Transportation Integrated Search

2011-01-01

Laboratory flume testing of native Utah non-salmonid fish was performed to observe how : they use altered flow around obstacles to swim upstream. Three experimental setups included : a bare Plexiglas flume, vertical cylinders, and natural substrate p...

VIEW OF PDP TANK TOP, LEVEL 0’, WITH LTR TANK ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF PDP TANK TOP, LEVEL 0’, WITH LTR TANK TOP ON LEFT, LOOKING NORTHEAST. CRANE AND VERTICAL HOISTING ELEMENTS AT TOP - Physics Assembly Laboratory, Area A/M, Savannah River Site, Aiken, Aiken County, SC

Cracking and debonding of a thin fiber reinforced concrete overlay.

DOT National Transportation Integrated Search

2017-04-01

Previous field studies suggested that macro-fibers incorporated in thin overlay pavements will result in reduced crack opening widths, vertical deflections, and debonding rates compared to that of unreinforced overlays. A simple finite element (FE) m...

[Finite element analysis of the stress distribution of two-piece post crown with different adhesives ].

PubMed

He, Lihui; Liu, Lijie; Gao, Bei; Gao, Shang; Chen, Yifu; Zhihui, Liu

2013-08-01

To establish three-dimensional finite element model of two-piece post crown to the mandibular first molar residual roots, and analyze the stress distribution characteristic to the residual roots with different adhesives, so as to get the best combination under different conditions. The complete mandibular first molar in vitro was selected, the crown was removed along the cemento-enamel junction, then the residual roots were scanned by CT. CT images were imported into a reverse engineering software, and the three-dimensional finite element model of the mandibular first molar residual roots was reconstructed. Titanium two-piece post crown of the mandibular first molar residual roots was produced, then was scanned by CT. The model was reconstructed and assembled by MIMICS. The stress distribution of the root canal and root section under the vertical load and lateral load with different bonding systems were analyzed. Three-dimensional finite element model of two-piece post crown to the mandibular first molar residual roots was established. With the increasing of elastic modulus of the adhesives, the maximum stress within the root canal was also increasing. Elastic modulus of zinc phosphate was the biggest, so the stress within the root canal was the biggest; elastic modulus of Superbond C&B was the smallest, so the stress within the root canal was the smallest. Lateral loading stress was much larger than the vertical load. Under vertical load, the load on the root section was even with different bonding systems. Under lateral load, the maximum stress was much larger than the vertical load. The stress on the root section was minimum using zinc phosphate binder, and the stress on the root section was maximum using Superbond C&B. In two-piece post crown restorations, there is significant difference between different adhesives on tooth protection. When the tooth structure of the root canal orifices is weak, in order to avoid the occurrence of splitting, the larger elastic modulus bonding system is the first choice, such as zinc phosphate binder. When the resistance form of the root canal orifices is good enough but the root is too weak, it is suggested that the smaller elastic modulus bonding system is the first choice, such as Superbond C&B.

Finite Element Simulations of Two Vertical Drop Tests of F-28 Fuselage Sections

NASA Technical Reports Server (NTRS)

Jackson, Karen E.; Littell, Justin D.; Annett, Martin S.; Haskin, Ian M.

2018-01-01

In March 2017, a vertical drop test of a forward fuselage section of a Fokker F-28 MK4000 aircraft was conducted as part of a joint NASA/FAA project to investigate the performance of transport aircraft under realistic crash conditions. In June 2017, a vertical drop test was conducted of a wing-box fuselage section of the same aircraft. Both sections were configured with two rows of aircraft seats, in a triple-double configuration. A total of ten Anthropomorphic Test Devices (ATDs) were secured in seats using standard lap belt restraints. The forward fuselage section was also configured with luggage in the cargo hold. Both sections were outfitted with two hat racks, each with added ballast mass. The drop tests were performed at the Landing and Impact Research facility located at NASA Langley Research Center in Hampton, Virginia. The measured impact velocity for the forward fuselage section was 346.8-in/s onto soil. The wing-box section was dropped with a downward facing pitch angle onto a sloping soil surface in order to create an induced forward acceleration in the airframe. The vertical impact velocity of the wing-box section was 349.2-in/s. A second objective of this project was to assess the capabilities of finite element simulations to predict the test responses. Finite element models of both fuselage sections were developed for execution in LS-DYNA(Registered Trademark), a commercial explicit nonlinear transient dynamic code. The models contained accurate representations of the airframe structure, the hat racks and hat rack masses, the floor and seat tracks, the luggage in the cargo hold for the forward section, and the detailed under-floor structure in the wing-box section. Initially, concentrated masses were used to represent the inertial properties of the seats, restraints, and ATD occupants. However, later simulations were performed that included finite element representations of the seats, restraints, and ATD occupants. These models were developed to more accurately replicate the seat loading of the floor and to enable prediction of occupant impact responses. Models were executed to generate analytical predictions of airframe responses, which were compared with test data to validate the model. Comparisons of predicted and experimental structural deformation and failures were made. Finally, predicted and experimental soil deformation and crater depths were also compared for both drop test configurations.

Sustained administration of corticosterone at stress-like levels after stroke suppressed glial reactivity at sites of thalamic secondary neurodegeneration.

PubMed

Zalewska, Katarzyna; Pietrogrande, Giovanni; Ong, Lin Kooi; Abdolhoseini, Mahmoud; Kluge, Murielle; Johnson, Sarah J; Walker, Frederick R; Nilsson, Michael

2018-03-01

Secondary neurodegeneration (SND) is an insidious and progressive condition involving the death of neurons in regions of the brain that were connected to but undamaged by the initial stroke. Our group have published compelling evidence that exposure to psychological stress can significantly exacerbate the severity SND, a finding that has considerable clinical implications given that stroke-survivors often report experiencing high and unremitting levels of psychological stress. It may be possible to use one or more targeted pharmacological approaches to limit the negative effects of stress on the recovery process but in order to move forward with this approach the most critical stress signals have to be identified. Accordingly, in the current study we have directed our attention to examining the potential effects of corticosterone, delivered orally at stress-like levels. Our interest is to determine how similar the effects of corticosterone are to stress on repair and remodelling that is known to occur after stroke. The study involved 4 groups, sham and stroke, either administered corticosterone or normal drinking water. The functional impact was assessed using the cylinder task for paw asymmetry, grid walk for sensorimotor function, inverted grid for muscle strength and coordination and open field for anxiety-like behaviour. Biochemically and histologically, we considered disturbances in main cellular elements of the neurovascular unit, including microglia, astrocytes, neurons and blood vessels using both immunohistochemistry and western blotting. In short, we identified that corticosterone delivery after stroke results in significant suppression of key microglial and astroglial markers. No changes were observed on the vasculature and in neuronal specific markers. No changes were identified for sensorimotor function or anxiety-like behaviour. We did, however, observe a significant change in motor function as assessed using the inverted grid walk test. Collectively, these results suggest that pharmacologically targeting corticosterone levels in the future may be warranted but that such an approach is unlikely to limit all the negative effects associated with exposure to chronic stress. Copyright © 2017 Elsevier Inc. All rights reserved.

[Three-dimensional finite element analysis of maxillary incisor retraction with step-shaped vertical closing loop].

PubMed

Zhang, Sheng; Mai, Li-xiang; Liu, Cong-hua; Wang, Da-wei

2011-07-01

To investigate the displacement and stress distribution of upper incisors in three-dimensional (3D) space controlled by step-shaped vertical closing loop. The maxillary teeth and alveolar bone of a volunteer with normal occlusion were scanned with 3D spiral CT. Modeling and calculation were only carried out on right upper central incisor, lateral incisor and their alveolar bone in order to simplify the procedures. A 3D finite element model of archwire-brackets-upper incisors and periodontal tissues was developed using Ansys finite element package. Finally, a 3D finite element model of archwire-brackets-upper incisors and periodontal tissues was established based on mirror symmetry principle. The displacement of maxillary incisors and stress distribution in periodontal tissues were analyzed. When step-shaped vertical closing loop was simply drew back 1 mm, the maximum displacement of upper central incisor in labial and lingual direction were 5.29 × 10(-2) and 0.71 × 10(-2) mm; 10.47 × 10(-3) and 10.20 × 10(-3) mm in gingival and occlusal direction, 10.26 × 10(-3) and 1.63 × 10(-3) mm in medial and distal direction; the maximum displacement of upper lateral incisor in labial and lingual direction were 3.31 × 10(-2) and 0.41 × 10(-2) mm, 10.52 × 10(-3) and 5.10 × 10(-3) mm in gingival and occlusal direction, 6.29 × 10(-3) and 4.64 × 10(-3) mm in medial and distal direction, the displacement trend of them were moving lingually and gingivally similar to bodily movement. The stress peach of upper central incisor, periodontal ligament and alveolar bone were 31.35, 2.52 and 4.64 MPa, the stress peach of upper lateral incisor, periodontal ligament and alveolar bone were 19.59, 1.28 and 4.12 Mpa, the stress distribution of them were similar and the periodontal ligament buffered the stress imposed on the tooth.

The effectiveness of a new algorithm on a three-dimensional finite element model construction of bone trabeculae in implant biomechanics.

PubMed

Sato, Y; Teixeira, E R; Tsuga, K; Shindoi, N

1999-08-01

More validity of finite element analysis (FEA) in implant biomechanics requires element downsizing. However, excess downsizing needs computer memory and calculation time. To evaluate the effectiveness of a new algorithm established for more valid FEA model construction without downsizing, three-dimensional FEA bone trabeculae models with different element sizes (300, 150 and 75 micron) were constructed. Four algorithms of stepwise (1 to 4 ranks) assignment of Young's modulus accorded with bone volume in the individual cubic element was used and then stress distribution against vertical loading was analysed. The model with 300 micron element size, with 4 ranks of Young's moduli accorded with bone volume in each element presented similar stress distribution to the model with the 75 micron element size. These results show that the new algorithm was effective, and the use of the 300 micron element for bone trabeculae representation was proposed, without critical changes in stress values and for possible savings on computer memory and calculation time in the laboratory.

The National Institute of Neurological Disorders and Stroke and Department of Defense Sport-Related Concussion Common Data Elements Version 1.0 Recommendations.

PubMed

Broglio, Steven P; Kontos, Anthony P; Levin, Harvey; Schneider, Kathryn; Wilde, Elisabeth A; Cantu, Robert C; Feddermann-Demont, Nina; Fuller, Gordon; Gagnon, Isabelle; Gioia, Gerry; Giza, Christopher C; Griesbach, Grace Sophia; Leddy, John J; Lipton, Michael L; Mayer, Andrew; McAllister, Thomas; McCrea, Michael; McKenzie, Lara; Putukian, Margot; Signoretti, Stefano; Suskauer, Stacy J; Tamburro, Robert; Turner, Michael; Yeates, Keith Owen; Zemek, Roger; Ala'i, Sherita; Esterlitz, Joy; Gay, Katelyn; Bellgowan, Patrick S F; Joseph, Kristen

2018-05-02

Through a partnership with the National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), and Department of Defense (DoD), the development of Sport-Related Concussion (SRC) Common Data Elements (CDEs) was initiated. The aim of this collaboration was to increase the efficiency and effectiveness of clinical research studies and clinical treatment outcomes, increase data quality, facilitate data sharing across studies, reduce study start-up time, more effectively aggregate information into metadata results, and educate new clinical investigators. The SRC CDE Working Group consisted of 34 worldwide experts in concussion from varied fields of related expertise, divided into three Subgroups: Acute (<72 hours post-concussion), Subacute (3 days-3 months post-concussion) and Persistent/Chronic (>3 months post-concussion). To develop CDEs, the Subgroups reviewed various domains, and then selected from, refined, and added to existing CDEs, case report forms and field-tested data elements from national registries and funded research studies. Recommendations were posted to the NINDS CDE Website for Public Review from February 2017 to April 2017. Following an internal Working Group review of recommendations, along with consideration of comments received from the Public Review period, the first iteration (Version 1.0) of the NINDS SRC CDEs was completed in June 2017. The recommendations include Core and Supplemental - Highly Recommended CDEs for cognitive data elements and symptom checklists, as well as other outcomes and endpoints (e.g., vestibular, oculomotor, balance, anxiety, depression) and sample case report forms (e.g., injury reporting, demographics, concussion history) for domains typically included in clinical research studies. The NINDS SRC CDEs and supporting documents are publicly available on the NINDS CDE website https://www.commondataelements.ninds.nih.gov/. Widespread use of CDEs by researchers and clinicians will facilitate consistent SRC clinical research and trial design, data sharing, and metadata retrospective analysis.

Methodological Rigor in Preclinical Cardiovascular Studies

PubMed Central

Ramirez, F. Daniel; Motazedian, Pouya; Jung, Richard G.; Di Santo, Pietro; MacDonald, Zachary D.; Moreland, Robert; Simard, Trevor; Clancy, Aisling A.; Russo, Juan J.; Welch, Vivian A.; Wells, George A.

2017-01-01

Rationale: Methodological sources of bias and suboptimal reporting contribute to irreproducibility in preclinical science and may negatively affect research translation. Randomization, blinding, sample size estimation, and considering sex as a biological variable are deemed crucial study design elements to maximize the quality and predictive value of preclinical experiments. Objective: To examine the prevalence and temporal patterns of recommended study design element implementation in preclinical cardiovascular research. Methods and Results: All articles published over a 10-year period in 5 leading cardiovascular journals were reviewed. Reports of in vivo experiments in nonhuman mammals describing pathophysiology, genetics, or therapeutic interventions relevant to specific cardiovascular disorders were identified. Data on study design and animal model use were collected. Citations at 60 months were additionally examined as a surrogate measure of research impact in a prespecified subset of studies, stratified by individual and cumulative study design elements. Of 28 636 articles screened, 3396 met inclusion criteria. Randomization was reported in 21.8%, blinding in 32.7%, and sample size estimation in 2.3%. Temporal and disease-specific analyses show that the implementation of these study design elements has overall not appreciably increased over the past decade, except in preclinical stroke research, which has uniquely demonstrated significant improvements in methodological rigor. In a subset of 1681 preclinical studies, randomization, blinding, sample size estimation, and inclusion of both sexes were not associated with increased citations at 60 months. Conclusions: Methodological shortcomings are prevalent in preclinical cardiovascular research, have not substantially improved over the past 10 years, and may be overlooked when basing subsequent studies. Resultant risks of bias and threats to study validity have the potential to hinder progress in cardiovascular medicine as preclinical research often precedes and informs clinical trials. Stroke research quality has uniquely improved in recent years, warranting a closer examination for interventions to model in other cardiovascular fields. PMID:28373349

Methodological Rigor in Preclinical Cardiovascular Studies: Targets to Enhance Reproducibility and Promote Research Translation.

PubMed

Ramirez, F Daniel; Motazedian, Pouya; Jung, Richard G; Di Santo, Pietro; MacDonald, Zachary D; Moreland, Robert; Simard, Trevor; Clancy, Aisling A; Russo, Juan J; Welch, Vivian A; Wells, George A; Hibbert, Benjamin

2017-06-09

Methodological sources of bias and suboptimal reporting contribute to irreproducibility in preclinical science and may negatively affect research translation. Randomization, blinding, sample size estimation, and considering sex as a biological variable are deemed crucial study design elements to maximize the quality and predictive value of preclinical experiments. To examine the prevalence and temporal patterns of recommended study design element implementation in preclinical cardiovascular research. All articles published over a 10-year period in 5 leading cardiovascular journals were reviewed. Reports of in vivo experiments in nonhuman mammals describing pathophysiology, genetics, or therapeutic interventions relevant to specific cardiovascular disorders were identified. Data on study design and animal model use were collected. Citations at 60 months were additionally examined as a surrogate measure of research impact in a prespecified subset of studies, stratified by individual and cumulative study design elements. Of 28 636 articles screened, 3396 met inclusion criteria. Randomization was reported in 21.8%, blinding in 32.7%, and sample size estimation in 2.3%. Temporal and disease-specific analyses show that the implementation of these study design elements has overall not appreciably increased over the past decade, except in preclinical stroke research, which has uniquely demonstrated significant improvements in methodological rigor. In a subset of 1681 preclinical studies, randomization, blinding, sample size estimation, and inclusion of both sexes were not associated with increased citations at 60 months. Methodological shortcomings are prevalent in preclinical cardiovascular research, have not substantially improved over the past 10 years, and may be overlooked when basing subsequent studies. Resultant risks of bias and threats to study validity have the potential to hinder progress in cardiovascular medicine as preclinical research often precedes and informs clinical trials. Stroke research quality has uniquely improved in recent years, warranting a closer examination for interventions to model in other cardiovascular fields. © 2017 The Authors.

Element soil behaviour during pile installation simulated by 2D-DEM

NASA Astrophysics Data System (ADS)

Ji, Xiaohui; Cheng, Yi Pik; Liu, Junwei

2017-06-01

The estimation of the skin friction of onshore or offshore piles in sand is still a difficult problem for geotechnical engineers. It has been accepted by many researchers that the mechanism of driving piles in the soil has shared some similarities with that of an element shear test under the constant normal stiffness (CNS) condition. This paper describes the behaviour of an element of soil next to a pile during the process of pile penetration into dense fine sand using the 2D-DEM numerical simulation software. A new CNS servo was added to the horizontal boundary while maintaining the vertical stress constant. This should simulate the soil in a similar manner to that of a CNS pile-soil interface shear test, but allowing the vertical stress to remain constant which is more realistic to the field situation. Shear behaviours observed in these simulations were very similar to the results from previous researchers' lab shearing tests. With the normal stress and shear stress obtained from the virtual models, the friction angle and the shaft friction factor β mentioned in the API-2007 offshore pile design guideline were calculated and compared with the API recommended values.

Angulated Dental Implants in Posterior Maxilla FEA and Experimental Verification

PubMed Central

Hamed, Hamed A.; Marzook, Hamdy A.; Ghoneem, Nahed E.; El–Anwar, Mohamed I.

2018-01-01

AIM: This study aimed to evaluate the effect of different implant angulations in posterior maxilla on stress distribution by finite element analysis and verify its results experimentally. METHODS: Two simplified models were prepared for an implant placed vertically and tilted 25° piercing the maxillary sinus. Geometric models’ components were prepared by Autodesk Inventor then assembled in ANSYS for finite element analysis. The results of finite element analysis were verified against experimental trials results which were statistically analysed using student t-test (level of significance p < 0.05). RESULTS: Implant - abutment complex absorbed the load energy in case of vertical implant better than the case of angulated one. That was reflected on cortical bone stress, while both cases showed stress levels within the physiological limits. Comparing results between FEA and experiment trials showed full agreement. CONCLUSION: It was found that the tilted implant by 25° can be utilised in the posterior region maxilla for replacing maxillary first molar avoiding sinus penetration. The implant-bone interface and peri-implant bones received the highest Von Mises stress. Implant - bone interface with angulated implant received about 66% more stresses than the straight one. PMID:29531612

Family history of stroke is potentially associated with arterial stiffness in the Japanese population.

PubMed

Uemura, Hirokazu; Katsuura-Kamano, Sakurako; Yamaguchi, Miwa; Nakamoto, Mariko; Hiyoshi, Mineyoshi; Arisawa, Kokichi

2014-12-01

Studies on the association between family history of cardiovascular disease and arterial stiffness are rare. This study evaluated the possible relationship between family history of cardiovascular disease and arterial stiffness in the Japanese population, by measuring brachial-ankle pulse wave velocity (ba-PWV). A total of 1004 eligible subjects (664 men and 340 women) aged 35-69 years, who were enrolled in the baseline survey of a cohort study in Tokushima Prefecture (Japan) and who underwent ba-PWV measurement, were analysed. Information about their lifestyle characteristics and first-degree family histories of ischaemic heart disease (i.e. myocardial infarction or angina pectoris), stroke or hypertension were obtained from a structural self-administered questionnaire. Subjects of both sexes with a family history of stroke showed significantly higher multivariable-adjusted means of ba-PWV than those without that trait (P values were 0.001 in men and 0.002 in women), while those with a family history of ischaemic heart disease did not. Subjects of both sexes with a family history of hypertension showed significantly higher age-adjusted means of ba-PWV than those without that trait, although these differences disappeared after further adjusting for blood pressure or multivariable covariates. When family histories of these diseases were inserted simultaneously into the same model, these results did not alter substantially. A family history of stroke might be associated with increased arterial stiffness, independent of other known atherosclerotic risk factors, including hypertensive elements, in both sexes in the Japanese population. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

An intermediate along the recovery stroke of myosin VI revealed by X-ray crystallography and molecular dynamics.

PubMed

Blanc, Florian; Isabet, Tatiana; Benisty, Hannah; Sweeney, H Lee; Cecchini, Marco; Houdusse, Anne

2018-06-12

Myosins form a class of actin-based, ATPase motor proteins that mediate important cellular functions such as cargo transport and cell motility. Their functional cycle involves two large-scale swings of the lever arm: the force-generating powerstroke, which takes place on actin, and the recovery stroke during which the lever arm is reprimed into an armed configuration. Previous analyses of the prerecovery (postrigor) and postrecovery (prepowerstroke) states predicted that closure of switch II in the ATP binding site precedes the movement of the converter and the lever arm. Here, we report on a crystal structure of myosin VI, called pretransition state (PTS), which was solved at 2.2 Å resolution. Structural analysis and all-atom molecular dynamics simulations are consistent with PTS being an intermediate along the recovery stroke, where the Relay/SH1 elements adopt a postrecovery conformation, and switch II remains open. In this state, the converter appears to be largely uncoupled from the motor domain and explores an ensemble of partially reprimed configurations through extensive, reversible fluctuations. Moreover, we found that the free energy cost of hydrogen-bonding switch II to ATP is lowered by more than 10 kcal/mol compared with the prerecovery state. These results support the conclusion that closing of switch II does not initiate the recovery stroke transition in myosin VI. Rather, they suggest a mechanism in which lever arm repriming would be mostly driven by thermal fluctuations and eventually stabilized by the switch II interaction with the nucleotide in a ratchet-like fashion.

Biomechanical study of three kinds of internal fixation for the treatment of sacroiliac joint disruption using biomechanical test and finite element analysis.

PubMed

Wu, Tao; Ren, Xuejiao; Cui, Yunwei; Cheng, Xiaodong; Peng, Shuo; Hou, Zhiyong; Han, Yongtai

2018-06-19

To compare the stability of sacroiliac joint disruption fixed with three kinds of internal fixation using both biomechanical test and finite element analysis. Five embalmed specimens of an adult were used. The symphysis pubis rupture and left sacroiliac joint disruption were created. The symphysis pubis was stabilized with a five-hole plate. The sacroiliac joint disruption was fixed with three kinds of internal fixation in a randomized design. Displacements of the whole specimen and shifts in the gap were recorded. Three-dimensional finite element models of the pelvis, the pelvis with symphysis pubis rupture and left sacroiliac joint disruption, and three kinds of internal fixation techniques were created and analyzed. Under the vertical load, the displacements and shifts in the gap of the pelvis fixed with minimally invasive adjustable plate (MIAP) combined with one iliosacral (IS) screw were the smallest, and the average displacements of the pelvis fixed with an anterior plate were the largest one. The differences among them were significant. In finite element analysis and MIAP combined with one IS screw fixation showed relatively best fixation stability and lowest risks of implant failure than two IS screws fixation and anterior plate fixation. The stability of sacroiliac joint disruption fixed with MIAP combined with one IS screw is better than that fixed with two IS screws and anterior plate under vertical load.

640 X 480 MOS PtSi IR sensor

NASA Astrophysics Data System (ADS)

Sauer, Donald J.; Shallcross, Frank V.; Hseuh, Fu-Lung; Meray, Grazyna M.; Levine, Peter A.; Gilmartin, Harvey R.; Villani, Thomas S.; Esposito, Benjamin J.; Tower, John R.

1991-12-01

The design of a 1st and 2nd generation 640(H) X 480(V) element PtSi Schottky-barrier infrared image sensor employing a low-noise MOS X-Y addressable readout multiplexer and on-chip low-noise output amplifier is described. Measured performance characteristics for Gen 1 devices are presented along with calculated performance for the Gen 2 design. A multiplexed horizontal/vertical input address port and on-chip decoding is used to load scan data into CMOS horizontal and vertical scanning registers. This allows random access to any sub-frame in the 640 X 480 element focal plane array. By changing the digital pattern applied to the vertical scan register, the FPA can be operated in either an interlaced or non- interlaced format, and the integration time may be varied over a wide range (60 microsecond(s) to > 30 ms, for RS170 operation) resulting in a form of 'electronic shutter,' or variable exposure control. The pixel size of 24-micrometers X 24-micrometers results in a fill factor of 38% for 1.5-micrometers process design rules. The overall die size for the IR imager is 13.7 mm X 17.2 mm. All digital inputs to the chip are TTL compatible and include ESD protection.

Acoustic tracking of sperm whales in the Gulf of Alaska using a two-element vertical array and tags.

PubMed

Mathias, Delphine; Thode, Aaron M; Straley, Jan; Andrews, Russel D

2013-09-01

Between 15 and 17 August 2010, a simple two-element vertical array was deployed off the continental slope of Southeast Alaska in 1200 m water depth. The array was attached to a vertical buoy line used to mark each end of a longline fishing set, at 300 m depth, close to the sound-speed minimum of the deep-water profile. The buoy line also served as a depredation decoy, attracting seven sperm whales to the area. One animal was tagged with both a LIMPET dive depth-transmitting satellite and bioacoustic "B-probe" tag. Both tag datasets were used as an independent check of various passive acoustic schemes for tracking the whale in depth and range, which exploited the elevation angles and relative arrival times of multiple ray paths recorded on the array. Analytical tracking formulas were viable up to 2 km range, but only numerical propagation models yielded accurate locations up to at least 35 km range at Beaufort sea state 3. Neither localization approach required knowledge of the local bottom bathymetry. The tracking system was successfully used to estimate the source level of an individual sperm whale's "clicks" and "creaks" and predict the maximum detection range of the signals as a function of sea state.

Three-dimensional finite element analysis on canine teeth distalization by different accessories of bracket-free invisible orthodontics technology

NASA Astrophysics Data System (ADS)

Xu, Nuo; Lei, Xue; Yang, Xiaoli; Li, Xinhui; Ge, Zhenlin

2018-04-01

Objective: to compare canine tooth stress distribution condition during maxillary canine tooth distalization by different accessories of bracket-free invisible orthodontics technology after removal of maxillary first premolar, and provide basis for clinical design of invisible orthodontics technology. Method: CBCT scanning image of a patient with individual normal occlusion was adopted, Mimics, Geomagic and ProlE software were used for establishing three-dimensional models of maxilla, maxillary dentition, parodontium, invisible orthodontics appliance and accessories, ANSYS WORKBENCH was utilized as finite element analysis tools for analyzing stress distribution and movement pattern of canine tooth and parodontium when canine tooth was equipped with power arm and vertical rectangle accessory. Meanwhile, canine tooth none-accessory design group was regarded as a control. Result: teeth had even bistal surface stress distribution in the power arm group; stress was concentrated on distal tooth neck, and the stress was gradually deviated to mesial-labial side and distal lingual side in vertical rectangle group and none-accessory group. Conclusion: teeth tend to move as a whole in the Power arm group, vertical rectangle group has lower tooth gradient compared with the none-accessory group, teeth are inclined for movement in the none-accessory group, and canine teeth tend to rotate to the distal lingual side.

Modeling the lateral load distribution for multiple concrete crossties and fastening systems.

DOT National Transportation Integrated Search

2017-01-31

The objective of this project was to further investigate the performance of concrete crosstie and : fastening system under vertical and lateral wheel load using finite element analysis, and explore : possible improvement for current track design stan...

An investigation of underwater sound propagation from pile driving.

DOT National Transportation Integrated Search

2011-12-01

The underwater noise from impact pile driving was studied by using a finite element model for the sound generation and a parabolic equation model for propagation. Results were compared with measurements taken with a vertical line array deployed durin...

Dimensions of landscape preferences from pairwise comparisons

Treesearch

F. González Bernaldez; F. Parra

1979-01-01

Analysis of landscape preferences allows the detection of major dimensions as:(1) the opposition between "natural and humanized", (comprising features like vegetation cover, cultivation, pattern of landscape elements, artifacts, excavations, etc.); (2) polarity "precision/ambiguity" (involving opposition between: predominance of straight, vertical...

On the mechanism of X-ray production by dart leaders of lightning flashes

NASA Astrophysics Data System (ADS)

Cooray, Vernon; Dwyer, Joseph; Rakov, V.; Rahman, Mahbubur

2010-07-01

Radiation with energies up to about 250 keV associated with the dart leader phase of rocket-triggered lightning were reported by Dwyer et al. (2004). The mechanism of X-ray generation by dart leaders, however, is unknown at present. Recently, Cooray et al. (2009a) developed physical concepts and mathematical techniques necessary to calculate the electric field associated with the tip of dart leaders. We have utilized the results of these calculations together with the energy dependent frictional force on electrons, as presented by Moss et al. (2006), to evaluate the maximum energy an electron will receive in accelerating in the dart-leader-tip electric field. The main assumptions made in performing the calculations are: (a) the dart leader channel is straight and vertical; (b) the path of the electrons are straight inside the channel; and (c) the decay of the channel temperature is uniform along the length of the dart leader. In the calculation, we have taken into account the fact that the electric field is changing both in space and time and that the gas in the defunct return stroke channel is at atmospheric pressure and at elevated temperature (i.e. reduced gas density). The results of the calculation show that for a given dart leader current there is a critical defunct-return-stroke-channel temperature above which the cold electron runaway becomes feasible. For a typical dart leader, this temperature is around 2500 K. This critical temperature decreases with increase in dart leader current. Since the temperature of the defunct return stroke channel may lie in the range of 2000-4000 K, the results show that the electric field at the tip of dart leaders is capable of accelerating electrons to MeV energy levels.

A Multisensor Investigation of Convection During HyMeX SOP1 IOP13

NASA Technical Reports Server (NTRS)

Roberto, N.; Adirosi, E.; Baldini, L.; Casella, D.; Dietrich, S.; Panegrossi, G.; Petracca, M.; Sano, P.; Gatlin, P.

2014-01-01

A multisensor analysis of the convective precipitation event occurred over Rome during the IOP13 (October 15th, 2012) of the HyMeX (Hydrological cycle in the Mediterranean eXperiment) Special Observation Period (SOP) 1 is presented. Thanks to the cooperation among Italian meteorological services and scientific community and a specific agreement with NASA-GSFC, different types of devices for meteorological measurements were made available during the HyMeX SOP.1. For investigating this event, used are the 3-D lightning data provided by the LINET, the CNR ISAC dual-pol C-band radar (Polar 55C), located in Rome, the Drop Size Distributions (DSD) collected by the 2D Video Disdrometer (2DVD) and the collocated Micro Rain Radar (MRR) installed at the Radio Meteorology Lab. of "Sapienza" University of Rome, located 14 km from the Polar 55C radar. The relation between microphysical structure and electrical activity during the convective phase of the event was investigated using LINET lightning data and Polar 55C (working both in PPI and RHI scanning mode) observations. Location of regions of high horizontal reflectivity (Zh) values ( > 50 dBz), indicating convective precipitation, were found to be associated to a high number of LINET strokes. In addition, an hydrometeor classification scheme applied to the Polar 55C scans was used to detect graupel and to identify a relation between number of LINET strokes and integrated IWC of graupel along the event. Properties of DSDs measured by the 2DVD and vertical DSD profiles estimated by MRR and their relation with the lighting activity registered by LINET were investigated with specific focus on the transition from convective to stratiform regimes. A good agreement was found between convection detected by these instruments and the number of strokes detected by LINET.

Kinematics and wing shape across flight speed in the bat, Leptonycteris yerbabuenae

PubMed Central

Von Busse, Rhea; Hedenström, Anders; Winter, York; Johansson, L. Christoffer

2012-01-01

Summary The morphology and kinematics of a flying animal determines the resulting aerodynamic lift through the regulation of the speed of the air moving across the wing, the wing area and the lift coefficient. We studied the detailed three-dimensional wingbeat kinematics of the bat, Leptonycteris yerbabuenae, flying in a wind tunnel over a range of flight speeds (0–7 m/s), to determine how factors affecting the lift production vary across flight speed and within wingbeats. We found that the wing area, the angle of attack and the camber, which are determinants of the lift production, decreased with increasing speed. The camber is controlled by multiple mechanisms along the span, including the deflection of the leg relative to the body, the bending of the fifth digit, the deflection of the leading edge flap and the upward bending of the wing tip. All these measures vary throughout the wing beat suggesting active or aeroelastic control. The downstroke Strouhal number, Std, is kept relatively constant, suggesting that favorable flow characteristics are maintained during the downstroke, across the range of speeds studied. The Std is kept constant through changes in the stroke plane, from a strongly inclined stroke plane at low speeds to a more vertical stroke plane at high speeds. The mean angular velocity of the wing correlates with the aerodynamic performance and shows a minimum at the speed of maximum lift to drag ratio, suggesting a simple way to determine the optimal speed from kinematics alone. Taken together our results show the high degree of adjustments that the bats employ to fine tune the aerodynamics of the wings and the correlation between kinematics and aerodynamic performance. PMID:23259057

Sonification as a possible stroke rehabilitation strategy

PubMed Central

Scholz, Daniel S.; Wu, Liming; Pirzer, Jonas; Schneider, Johann; Rollnik, Jens D.; Großbach, Michael; Altenmüller, Eckart O.

2014-01-01

Despite cerebral stroke being one of the main causes of acquired impairments of motor skills worldwide, well-established therapies to improve motor functions are sparse. Recently, attempts have been made to improve gross motor rehabilitation by mapping patient movements to sound, termed sonification. Sonification provides additional sensory input, supplementing impaired proprioception. However, to date no established sonification-supported rehabilitation protocol strategy exists. In order to examine and validate the effectiveness of sonification in stroke rehabilitation, we developed a computer program, termed “SonicPointer”: Participants' computer mouse movements were sonified in real-time with complex tones. Tone characteristics were derived from an invisible parameter mapping, overlaid on the computer screen. The parameters were: tone pitch and tone brightness. One parameter varied along the x, the other along the y axis. The order of parameter assignment to axes was balanced in two blocks between subjects so that each participant performed under both conditions. Subjects were naive to the overlaid parameter mappings and its change between blocks. In each trial a target tone was presented and subjects were instructed to indicate its origin with respect to the overlaid parameter mappings on the screen as quickly and accurately as possible with a mouse click. Twenty-six elderly healthy participants were tested. Required time and two-dimensional accuracy were recorded. Trial duration times and learning curves were derived. We hypothesized that subjects performed in one of the two parameter-to-axis–mappings better, indicating the most natural sonification. Generally, subjects' localizing performance was better on the pitch axis as compared to the brightness axis. Furthermore, the learning curves were steepest when pitch was mapped onto the vertical and brightness onto the horizontal axis. This seems to be the optimal constellation for this two-dimensional sonification. PMID:25368548

Three-dimensional spatial cognition in a benthic fish, Corydoras aeneus.

PubMed

Davis, V A; Holbrook, R I; Schumacher, S; Guilford, T; de Perera, T Burt

2014-11-01

The way animals move through space is likely to affect the way they learn and remember spatial information. For example, a pelagic fish, Astyanax fasciatus, moves freely in vertical and horizontal space and encodes information from both dimensions with similar accuracy. Benthic fish can also move with six degrees of freedom, but spend much of their time travelling over the substrate; hence they might be expected to prioritise the horizontal dimension. To understand how benthic fish encode and deploy three-dimensional spatial information we used a fully rotational Y-maze to test whether Corydoras aeneus (i) encode space as an integrated three-dimensional unit or as separate elements, by testing whether they can decompose a three-dimensional trajectory into its vertical and horizontal components, and (ii) whether they prioritise vertical or horizontal information when the two conflict. In contradiction to the expectation generated by our hypothesis, our results suggest that C. aeneus are better at extracting vertical information than horizontal information from a three-dimensional trajectory, suggesting that the vertical axis is learned and remembered robustly. Our results also showed that C. aeneus prioritise vertical information when it conflicts with horizontal information. From these results, we infer that benthic fish attend preferentially to a cue unique to the vertical axis, and we suggest that this cue is hydrostatic pressure. Copyright © 2014 Elsevier B.V. All rights reserved.

Lattice Boltzmann simulations of the bead-spring microswimmer with a responsive stroke—from an individual to swarms

NASA Astrophysics Data System (ADS)

Pickl, Kristina; Pande, Jayant; Köstler, Harald; Rüde, Ulrich; Smith, Ana-Sunčana

2017-03-01

Propulsion at low Reynolds numbers is often studied by defining artificial microswimmers which exhibit a particular stroke. The disadvantage of such an approach is that the stroke does not adjust to the environment, in particular the fluid flow, which can diminish the effect of hydrodynamic interactions. To overcome this limitation, we simulate a microswimmer consisting of three beads connected by springs and dampers, using the self-developed waLBerla and pe framework based on the lattice Boltzmann method and the discrete element method. In our approach, the swimming stroke of a swimmer emerges as a balance of the drag, the driving and the elastic internal forces. We validate the simulations by comparing the obtained swimming velocity to the velocity found analytically using a perturbative method where the bead oscillations are taken to be small. Including higher-order terms in the hydrodynamic interactions between the beads improves the agreement to the simulations in parts of the parameter space. Encouraged by the agreement between the theory and the simulations and aided by the massively parallel capabilities of the waLBerla-pe framework, we simulate more than ten thousand such swimmers together, thus presenting the first fully resolved simulations of large swarms with active responsive components.

The Neural Correlates of Long-Term Carryover following Functional Electrical Stimulation for Stroke.

PubMed

Gandolla, Marta; Ward, Nick S; Molteni, Franco; Guanziroli, Eleonora; Ferrigno, Giancarlo; Pedrocchi, Alessandra

2016-01-01

Neurorehabilitation effective delivery for stroke is likely to be improved by establishing a mechanistic understanding of how to enhance adaptive plasticity. Functional electrical stimulation is effective at reducing poststroke foot drop; in some patients, the effect persists after therapy has finished with an unknown mechanism. We used fMRI to examine neural correlates of functional electrical stimulation key elements, volitional intent to move and concurrent stimulation, in a group of chronic stroke patients receiving functional electrical stimulation for foot-drop correction. Patients exhibited task-related activation in a complex network, sharing bilateral sensorimotor and supplementary motor activation with age-matched controls. We observed consistent separation of patients with and without carryover effect on the basis of brain responses. Patients who experienced the carryover effect had responses in supplementary motor area that correspond to healthy controls; the interaction between experimental factors in contralateral angular gyrus was seen only in those without carryover. We suggest that the functional electrical stimulation carryover mechanism of action is based on movement prediction and sense of agency/body ownership-the ability of a patient to plan the movement and to perceive the stimulation as a part of his/her own control loop is important for carryover effect to take place.

The difference between a dynamic and mechanical approach to stroke treatment.

PubMed

Helgason, Cathy M

2007-06-01

The current classification of stroke is based on causation, also called pathogenesis, and relies on binary logic faithful to the Aristotelian tradition. Accordingly, a pathology is or is not the cause of the stroke, is considered independent of others, and is the target for treatment. It is the subject for large double-blind randomized clinical therapeutic trials. The scientific view behind clinical trials is the fundamental concept that information is statistical, and causation is determined by probabilities. Therefore, the cause and effect relation will be determined by probability-theory-based statistics. This is the basis of evidence-based medicine, which calls for the results of such trials to be the basis for physician decisions regarding diagnosis and treatment. However, there are problems with the methodology behind evidence-based medicine. Calculations using probability-theory-based statistics regarding cause and effect are performed within an automatic system where there are known inputs and outputs. This method of research provides a framework of certainty with no surprise elements or outcomes. However, it is not a system or method that will come up with previously unknown variables, concepts, or universal principles; it is not a method that will give a new outcome; and it is not a method that allows for creativity, expertise, or new insight for problem solving.

"FIND Technology": investigating the feasibility, efficacy and safety of controller-free interactive digital rehabilitation technology in an inpatient stroke population: study protocol for a randomized controlled trial.

PubMed

Bird, M L; Cannell, J; Callisaya, M L; Moles, E; Rathjen, A; Lane, K; Tyson, A; Smith, S

2016-04-16

Stroke results in significant disability, which can be reduced by physical rehabilitation. High levels of repetition and activity are required in rehabilitation, but patients are typically sedentary. Using clinically relevant and fun computer games may be one way to achieve increased activity in rehabilitation. A single-blind randomized controlled trial will be conducted to evaluate the feasibility, efficacy and safety of novel stroke-specific rehabilitation software. This software uses controller-free client interaction and inertial motion sensors. Elements of feasibility include recruitment into the trial, ongoing participation (adherence and dropout), perceived benefit, enjoyment and ease of use of the games. Efficacy will be determined by measuring activity and using upper-limb tasks as well as measures of balance and mobility. The hypothesis that the intervention group will have increased levels of physical activity within rehabilitation and improved physical outcomes compared with the control group will be tested. Results from this study will provide a basis for discussion of feasibility of this interactive video technological solution in an inpatient situation. Differences in activity levels between groups will be the primary measure of efficacy. It will also provide data on measures of upper-limb function, balance and mobility. ACTRN12614000427673 . Prospectively registered 17 April 2014.

The Kinematics of Trunk and Upper Extremities in One-Handed and Two-Handed Backhand Stroke

PubMed Central

Stępień, Adam; Bober, Tadeusz; Zawadzki, Jerzy

2011-01-01

The aim of this study was to present kinematics of trunk and upper extremities in tennis players who perform one-handed and two-handed backhand strokes. The study aimed to address the question of whether one of those techniques has some important advantage over the other. If so, what makes it superior? The study included 10 tennis coaches with average coaching experience of 9 years. The coaches were asked to hit 15 one-handed and two-handed backhands. The tests were carried out in a laboratory. A sponge ball was used in order to protect the measurement equipment. Video motion analysis was carried out using BTS SMART system; images were recorded with 6 cameras with a rate of 120 frames per second. The analysis of both backhand strokes focused on the second phase of the stroke (acceleration). The use of an eight-element model of human body for description of upper body motion in both techniques revealed kinematic differences in how both backhands are performed. The two-handed backhand was performed in closed kinetic chain with 8 degrees of freedom, whereas the one-handed backhand involved an open kinetic chain with 7 degrees of freedom. Higher rigidity of upper extremities which are connected with trunk in the two-handed backhand, contributes to an elevated trunk effect in this stroke. This is confirmed by higher component velocities for racket handle, which result from trunk rotation in the two-handed backhand and a negative separation angle in the two-handed backhand at the moment of contact of the racket with the ball. The study does not provide a clear-cut answer to the question of advantages of one technique over the other; however, it reveals dissimilar patterns of driving the racket in both techniques, which suggests the need for extending the analysis of techniques of both backhands with additional kinematics of tennis racket in consideration of measurements of ball velocities. PMID:23486650

High-Speed Semiconductor Vertical-Cavity Surface-Emitting Lasers for Optical Data-Transmission Systems (Review)

NASA Astrophysics Data System (ADS)

Blokhin, S. A.; Maleev, N. A.; Bobrov, M. A.; Kuzmenkov, A. G.; Sakharov, A. V.; Ustinov, V. M.

2018-01-01

The main problems of providing a high-speed operation semiconductor lasers with a vertical microcavity (so-called "vertical-cavity surface-emitting lasers") under amplitude modulation and ways to solve them have been considered. The influence of the internal properties of the radiating active region and the electrical parasitic elements of the equivalent circuit of lasers are discussed. An overview of approaches that lead to an increase of the cutoff parasitic frequency, an increase of the differential gain of the active region, the possibility of the management of mode emission composition and the lifetime of photons in the optical microcavities, and reduction of the influence of thermal effects have been presented. The achieved level of modulation bandwidth of ˜30 GHz is close to the maximum achievable for the classical scheme of the direct-current modulation, which makes it necessary to use a multilevel modulation format to further increase the information capacity of optical channels constructed on the basis of vertical-cavity surface-emitting lasers.

Compact ultra-fast vertical nanopositioner for improving scanning probe microscope scan speed

NASA Astrophysics Data System (ADS)

Kenton, Brian J.; Fleming, Andrew J.; Leang, Kam K.

2011-12-01

The mechanical design of a high-bandwidth, short-range vertical positioning stage is described for integration with a commercial scanning probe microscope (SPM) for dual-stage actuation to significantly improve scanning performance. The vertical motion of the sample platform is driven by a stiff and compact piezo-stack actuator and guided by a novel circular flexure to minimize undesirable mechanical resonances that can limit the performance of the vertical feedback control loop. Finite element analysis is performed to study the key issues that affect performance. To relax the need for properly securing the stage to a working surface, such as a laboratory workbench, an inertial cancellation scheme is utilized. The measured dominant unloaded mechanical resonance of a prototype stage is above 150 kHz and the travel range is approximately 1.56 μm. The high-bandwidth stage is experimentally evaluated with a basic commercial SPM, and results show over 25-times improvement in the scanning performance.

Vertical export flux of metals in the Mediterranean Sea

NASA Astrophysics Data System (ADS)

Heimbürger, Lars-Eric; Migon, Christophe; Losno, Rémi; Miquel, Juan-Carlos; Thibodeau, Benoît; Stabholz, Marion; Dufour, Aurélie; Leblond, Nathalie

2014-05-01

We examined metal (Al, V, Cr, Mn, Fe, Ni, Cu, Zn, Cd and Pb) and particulate organic carbon (OC) concentrations of the marine vertical export flux at the DYFAMED time-series station in the Northwestern Mediterranean Sea. We present here the first data set of natural and anthropogenic metals from sediment trap moorings deployed at 1000 m-depth between 2003 and 2007 at the DYFAMED site. A highly significant correlation was observed between most metal concentrations, whatever the nature and emission source of the metal. Cu, Zn and Cd exhibit different behaviors, presumably due to their high solubility and complexation with organic ligands. The observed difference of atmospheric and marine fluxes in terms of temporal variability and elemental concentration suggests that dense water convection and primary production and not atmospheric deposition control the marine vertical export flux. This argument is strengthened by the fact that significant Saharan dust events did not result in concomitant marine vertical export fluxes nor did they generate significant changes in metal concentrations of trapped particles.

Trajectory optimization for lunar rover performing vertical takeoff vertical landing maneuvers in the presence of terrain

NASA Astrophysics Data System (ADS)

Ma, Lin; Wang, Kexin; Xu, Zuhua; Shao, Zhijiang; Song, Zhengyu; Biegler, Lorenz T.

2018-05-01

This study presents a trajectory optimization framework for lunar rover performing vertical takeoff vertical landing (VTVL) maneuvers in the presence of terrain using variable-thrust propulsion. First, a VTVL trajectory optimization problem with three-dimensional kinematics and dynamics model, boundary conditions, and path constraints is formulated. Then, a finite-element approach transcribes the formulated trajectory optimization problem into a nonlinear programming (NLP) problem solved by a highly efficient NLP solver. A homotopy-based backtracking strategy is applied to enhance the convergence in solving the formulated VTVL trajectory optimization problem. The optimal thrust solution typically has a "bang-bang" profile considering that bounds are imposed on the magnitude of engine thrust. An adaptive mesh refinement strategy based on a constant Hamiltonian profile is designed to address the difficulty in locating the breakpoints in the thrust profile. Four scenarios are simulated. Simulation results indicate that the proposed trajectory optimization framework has sufficient adaptability to handle VTVL missions efficiently.

Flight Control of Biomimetic Air Vehicles Using Vibrational Control and Averaging

NASA Astrophysics Data System (ADS)

Tahmasian, Sevak; Woolsey, Craig A.

2017-08-01

A combination of vibrational inputs and state feedback is applied to control the flight of a biomimetic air vehicle. First, a control strategy is developed for longitudinal flight, using a quasi-steady aerodynamic model and neglecting wing inertial effects. Vertical and forward motion is controlled by modulating the wings' stroke and feather angles, respectively. Stabilizing control parameter values are determined using the time-averaged dynamic model. Simulations of a system resembling a hawkmoth show that the proposed controller can overcome modeling error associated with the wing inertia and small parameter uncertainties when following a prescribed trajectory. After introducing the approach through an application to longitudinal flight, the control strategy is extended to address flight in three-dimensional space.

Slant rectification in Russian passport OCR system using fast Hough transform

NASA Astrophysics Data System (ADS)

Limonova, Elena; Bezmaternykh, Pavel; Nikolaev, Dmitry; Arlazarov, Vladimir

2017-03-01

In this paper, we introduce slant detection method based on Fast Hough Transform calculation and demonstrate its application in industrial system for Russian passports recognition. About 1.5% of this kind of documents appear to be slant or italic. This fact reduces recognition rate, because Optical Recognition Systems are normally designed to process normal fonts. Our method uses Fast Hough Transform to analyse vertical strokes of characters extracted with the help of x-derivative of a text line image. To improve the quality of detector we also introduce field grouping rules. The resulting algorithm allowed to reach high detection quality. Almost all errors of considered approach happen on passports of nonstandard fonts, while slant detector works in appropriate way.

Ship Production Symposium Held in Long Beach, California on September 11-13, 1985. Volume 2 (The National Shipbuilding Research Program)

DTIC Science & Technology

1985-09-01

t h e long- term we are comple te ly redes ign ing the Weapon Systems F i le c o m p u t e r s o f t w a r e s o t h a t i t i s f u l l y ...sidewall 6) ability to repair surface defects by carbon arcing and grinding -572- LIST OF REFERENCES 1) Kimura, S., Ichihara, I., and Nagai, Y ...5.5 inch/min) (50/60 Hz) Stroke: 350mm (I 3.8 inch) electric inching method M o u n t i n g A s s e m b l y ) Vertical Head adjustment Slide speed

Production of aluminum-silicon alloy and ferrosilicon and commercial purity aluminum by the direct reduction process. Second interim technical report, Phase C for the period 1980 April 1-1980 June 30

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruno, M.J.

1980-10-01

Beneficiation of bauxite by high intensity wet magnetic separation to remove Fe and Ti was not successful. Pilot reactor VSR-3 was modified and operated to evaluate the blast-arc reduction process concept. Modifications included a tapered upper shaft section, vertical stroke ram, and CO preheater system. The taper/ram revisions were successful in maintaining bed movement, resulting in several continuous runs in which large quantities of burden were fed and metal product was recovered. Pilot VSR samples were also analyzed. The major phases contained Si and FeSi/sub 2/Al/sub 4/ intermetallics in a matrix of eutectic Al-Si.

D region disturbances caused by electromagnetic pulses from lightning

NASA Technical Reports Server (NTRS)

Rodriguez, Juan V.; Inan, Umran S.; Bell, Timothy F.

1992-01-01

Attention is given to a simple formulation of the propagation and absorption in a magnetized collisional plasma of EM pulses from lightning which describes the effect of discharge orientation and radiated electric field on the structure and magnitude of heating and secondary ionization in the D region. Radiation from most lightning discharges can heat substantially, but only the most intense (not less than 20 V/m) are likely to cause ionization enhancements not less than 10 percent of the ambient in a single ionization cycle. This dependence on the radiated electric field is modified by the discharge radiation pattern: a horizontal cloud discharge tends to cause larger heating and ionizaton maxima while a vertical return stroke causes disturbances of a larger horizontal extent.

Vertical ground motion and its effects on liquefaction resistance of fully saturated sand deposits

PubMed Central

Kontoe, Stavroula; Taborda, David M. G.; Potts, David M.

2016-01-01

Soil liquefaction has been extensively investigated over the years with the aim to understand its fundamental mechanism and successfully remediate it. Despite the multi-directional nature of earthquakes, the vertical seismic component is largely neglected, as it is traditionally considered to be of much lower amplitude than the components in the horizontal plane. The 2010–2011 Canterbury earthquake sequence in New Zealand is a prime example that vertical accelerations can be of significant magnitude, with peak amplitudes well exceeding their horizontal counterparts. As research on this topic is very limited, there is an emerging need for a more thorough investigation of the vertical motion and its effect on soil liquefaction. As such, throughout this study, uni- and bidirectional finite-element analyses are carried out focusing on the influence of the input vertical motion on sand liquefaction. The effects of the frequency content of the input motion, of the depth of the deposit and of the hydraulic regime, using variable permeability, are investigated and exhaustively discussed. The results indicate that the usual assumption of linear elastic response when compressional waves propagate in a fully saturated sand deposit does not always hold true. Most importantly post-liquefaction settlements appear to be increased when the vertical component is included in the analysis. PMID:27616931

Vertical ground motion and its effects on liquefaction resistance of fully saturated sand deposits.

PubMed

Tsaparli, Vasiliki; Kontoe, Stavroula; Taborda, David M G; Potts, David M

2016-08-01

Soil liquefaction has been extensively investigated over the years with the aim to understand its fundamental mechanism and successfully remediate it. Despite the multi-directional nature of earthquakes, the vertical seismic component is largely neglected, as it is traditionally considered to be of much lower amplitude than the components in the horizontal plane. The 2010-2011 Canterbury earthquake sequence in New Zealand is a prime example that vertical accelerations can be of significant magnitude, with peak amplitudes well exceeding their horizontal counterparts. As research on this topic is very limited, there is an emerging need for a more thorough investigation of the vertical motion and its effect on soil liquefaction. As such, throughout this study, uni- and bidirectional finite-element analyses are carried out focusing on the influence of the input vertical motion on sand liquefaction. The effects of the frequency content of the input motion, of the depth of the deposit and of the hydraulic regime, using variable permeability, are investigated and exhaustively discussed. The results indicate that the usual assumption of linear elastic response when compressional waves propagate in a fully saturated sand deposit does not always hold true. Most importantly post-liquefaction settlements appear to be increased when the vertical component is included in the analysis.

Recommendations for the National Institute for Neurologic Disorders and Stroke spinal cord injury common data elements for children and youth with SCI.

PubMed

Mulcahey, M J; Vogel, L C; Sheikh, M; Arango-Lasprilla, J C; Augutis, M; Garner, E; Hagen, E M; Jakeman, L B; Kelly, E; Martin, R; Odenkirchen, J; Scheel-Sailer, A; Schottler, J; Taylor, H; Thielen, C C; Zebracki, K

2017-04-01

In 2014, the adult spinal cord injury (SCI) common data element (CDE) recommendations were made available. This project was a review of the adult SCI CDE for relevance to children and youth with SCI. The objective of this study was to review the National Institute of Neurologic Disorders and Stroke (NINDS) adult SCI CDEs for relevance to children and youth with SCI. International. The pediatric working group consisted of international members with varied fields of expertise related to pediatric SCI. The group convened biweekly meetings for 6 months in 2015. All of the adult SCI CDEs were reviewed, evaluated and modified/created for four age groups: 0-5 years, 6-12 years, 13-15 years and 16-18 years. Whenever possible, results of published research studies were used to guide recommendations. In the absence of empirical support, grey literature and international content expert consensus were garnered. Existing pediatric NINDS CDEs and new CDEs were developed in areas where adult recommendations were not appropriate. After internal working group review of domain recommendations, these pediatric CDEs were vetted during a public review from November through December 2015. Version 1.0 of the pediatric SCI CDEs was posted in February 2016. The pediatric SCI CDEs are incorporated directly into the NINDS SCI CDE sets and can be found at https://commondataelements.ninds.nih.gov.

Monitoring trace elements generated by automobiles: air pollutants with possible health impacts.

PubMed

Anwar, Khaleeq; Ejaz, Sohail; Ashraf, Muhammad; Ahmad, Nisar; Javeed, Aqeel

2013-07-01

Major transformations in the environmental composition are principally attributable to the combustion of fuels by automobiles. Motorized gasoline-powered two-stroke auto-rickshaws (TSA) and compressed natural gas (CNG)-powered four-stroke auto-rickshaws (FSA) are potential source of air pollution in south Asia and produce toxic amount of particulate matter (PM) to the environment. In this study, we attempted to characterize elemental pollutants from the PM of TSA and FSA using proton-induced X-ray emission (PIXE) analysis. The observations of the existing investigation recognized significant increase in Al (P < 0.05), P (P < 0.01), and Zn (P < 0.01) from the PM samples of FSA. In addition, the concentrations of Cu, Fe, K, Mg, Na and S were also observed exceeding the recommended National Institute for Environmental Studies limits. On the contrary, increased concentration of Sr and V were observed in the PM samples from TSA. It is generally believed that FSA generates smaller amount of PM but data obtained from FSA are clearly describing that emissions from FSA comprised potentially more toxic substances than TSA. The current research is specific to metropolitan population and has evidently revealed an inconsistent burden of exposure to air pollutants engendered by FSA in urban communities, which could lead to the disruption of several biological activities and may cause severe damage to entire ecological system.

Humidification during high-frequency oscillation ventilation is affected by ventilator circuit and ventilatory setting.

PubMed

Chikata, Yusuke; Imanaka, Hideaki; Onishi, Yoshiaki; Ueta, Masahiko; Nishimura, Masaji

2009-08-01

High-frequency oscillation ventilation (HFOV) is an accepted ventilatory mode for acute respiratory failure in neonates. As conventional mechanical ventilation, inspiratory gas humidification is essential. However, humidification during HFOV has not been clarified. In this bench study, we evaluated humidification during HFOV in the open circumstance of ICU. Our hypothesis is that humidification during HFOV is affected by circuit design and ventilatory settings. We connected a ventilator with HFOV mode to a neonatal lung model that was placed in an infant incubator set at 37 degrees C. We set a heated humidifier (Fisher & Paykel) to obtain 37 degrees C at the chamber outlet and 40 degrees C at the distal temperature probe. We measured absolute humidity and temperature at the Y-piece using a rapid-response hygrometer. We evaluated two types of ventilator circuit: a circuit with inner heating wire and another with embedded heating element. In addition, we evaluated three lengths of the inspiratory limb, three stroke volumes, three frequencies, and three mean airway pressures. The circuit with embedded heating element provided significantly higher absolute humidity and temperature than one with inner heating wire. As an extended tube lacking a heating wire was shorter, absolute humidity and temperature became higher. In the circuit with inner heating wire, absolute humidity and temperature increased as stroke volume increased. Humidification during HFOV is affected by circuit design and ventilatory settings.

Role of Pectoral Fin Flexibility in Robotic Fish Performance

NASA Astrophysics Data System (ADS)

Bazaz Behbahani, Sanaz; Tan, Xiaobo

2017-08-01

Pectoral fins play a vital role in the maneuvering and locomotion of fish, and they have become an important actuation mechanism for robotic fish. In this paper, we explore the effect of flexibility of robotic fish pectoral fins on the robot locomotion performance and mechanical efficiency. A dynamic model for the robotic fish is presented, where the flexible fin is modeled as multiple rigid elements connected via torsional springs and dampers. Blade element theory is used to capture the hydrodynamic force on the fin. The model is validated with experimental results obtained on a robotic fish prototype, equipped with 3D-printed fins of different flexibility. The model is then used to analyze the impacts of fin flexibility and power/recovery stroke speed ratio on the robot swimming speed and mechanical efficiency. It is found that, in general, flexible fins demonstrate advantages over rigid fins in speed and efficiency at relatively low fin-beat frequencies, while rigid fins outperform flexible fins at higher frequencies. For a given fin flexibility, the optimal frequency for speed performance differs from the optimal frequency for mechanical efficiency. In addition, for any given fin, there is an optimal power/recovery stroke speed ratio, typically in the range of 2-3, that maximizes the speed performance. Overall, the presented model offers a promising tool for fin flexibility and gait design, to achieve speed and efficiency objectives for robotic fish actuated with pectoral fins.

Magnetic field generated by lightning protection system

NASA Astrophysics Data System (ADS)

Geri, A.; Veca, G. M.

1988-04-01

A lightning protection system for today's civil buildings must be electromagnetically compatible with the electronic equipment present in the building. This paper highlights a mathematic model which analyzes the electromagnetic effects in the environment in which the lightning protection system is. This model is developed by means of finite elements of an electrical circuit where each element is represented by a double pole circuit according to the trapezoidal algorithm developed using the finite difference method. It is thus possible to analyze the electromagnetic phenomena associated with the transient effects created by the lightning stroke even for a high-intensity current. Referring to an elementary system comprised of an air terminal, a down conductor, and a ground terminal, numerical results are here laid out.

Virtual reality environments for post-stroke arm rehabilitation.

PubMed

Subramanian, Sandeep; Knaut, Luiz A; Beaudoin, Christian; McFadyen, Bradford J; Feldman, Anatol G; Levin, Mindy F

2007-06-22

Optimal practice and feedback elements are essential requirements for maximal motor recovery in patients with motor deficits due to central nervous system lesions. A virtual environment (VE) was created that incorporates practice and feedback elements necessary for maximal motor recovery. It permits varied and challenging practice in a motivating environment that provides salient feedback. The VE gives the user knowledge of results feedback about motor behavior and knowledge of performance feedback about the quality of pointing movements made in a virtual elevator. Movement distances are related to length of body segments. We describe an immersive and interactive experimental protocol developed in a virtual reality environment using the CAREN system. The VE can be used as a training environment for the upper limb in patients with motor impairments.

Changes in kinetics and kinematics of handwriting during a prolonged writing task in children with and without dysgraphia.

PubMed

Kushki, Azadeh; Schwellnus, Heidi; Ilyas, Faizah; Chau, Tom

2011-01-01

Handwriting difficulties or dysgraphia have a profound impact on children's psychosocial development, and yet, 10-30% of school-aged children are reported to experience difficulties mastering this skill. Several studies have examined the nature and biomechanical underpinnings of handwriting difficulties in children with and without dysgraphia. While the majority of these studies have considered short handwriting activities involving a sentence or a paragraph, handwriting quality and speed are reported to vary with the length of the writing task. Further, it is suggested that the biomechanics of handwriting also evolve over extended writing periods, and that these changes may be distinct between children with and without dysgraphia. The nature and specificity of these biomechanical alterations remain unknown. To address this knowledge gap, we examined changes in writing speed, grip forces on the pen barrel, and normal forces on the writing surface, over the course of a 10-min writing task, in a large cohort of 4th grade children with and without dysgraphia. Horizontal stroke speed, grip force and normal force increased over time while vertical stroke speed decreased in all children. These biomechanical changes may be attributable to physical and psychological fatigue and the corresponding compensatory processes invoked by the motor system. Copyright © 2011 Elsevier Ltd. All rights reserved.

Pusher syndrome--a frequent but little-known disturbance of body orientation perception.

PubMed

Karnath, Hans-Otto

2007-04-01

Disturbances of body orientation perception after brain lesions may specifically relate to only one dimension of space. Stroke patients with "pusher syndrome" suffer from a severe misperception of their body's orientation in the coronal (roll) plane. They experience their body as oriented 'upright' when it is in fact markedly tilted to one side. The patients use the unaffected arm or leg to actively push away from the un-paralyzed side and resist any attempt to passively correct their tilted body posture. Although pusher patients are unable to correctly determine when their own body is oriented in an upright, vertical position, they seem to have no significant difficulty in determining the orientation of the surrounding visual world in relation to their own body. Pusher syndrome is a distinctive clinical disorder occurring characteristically after unilateral left or right brain lesions in the posterior thalamus and -less frequently- in the insula and postcentral gyrus. These structures thus seem to constitute crucial neural substrates controlling human (upright) body orientation in the coronal (roll) plane. A further disturbance of body orientation that predominantly affects a single dimension of space, namely the transverse (yaw) plane, is observed in stroke patients with spatial neglect. Apparently, our brain has evolved separate neural subsystems for perceiving and controlling body orientation in different dimensions of space.

Development and presentation of a roadway and roadside design course : final report, December 2009.

DOT National Transportation Integrated Search

2009-12-01

The overall goal of this course is to provide training in the elements of geometric highway : design. Specific course objectives are: : To review the geometry of horizontal and vertical alignment including simple circular : curves, compound curve...

47 CFR 73.186 - Establishment of effective field at one kilometer.

Code of Federal Regulations, 2013 CFR

2013-10-01

... radiation (not less than one wave length or 5 times the vertical height in the case of a single element, i.e... lieu of the required minimum physical heights of the antennas proper. Also, in other situations, it may...

47 CFR 73.186 - Establishment of effective field at one kilometer.

Code of Federal Regulations, 2014 CFR

2014-10-01

... radiation (not less than one wave length or 5 times the vertical height in the case of a single element, i.e... lieu of the required minimum physical heights of the antennas proper. Also, in other situations, it may...

47 CFR 73.186 - Establishment of effective field at one kilometer.

Code of Federal Regulations, 2012 CFR

2012-10-01

... radiation (not less than one wave length or 5 times the vertical height in the case of a single element, i.e... lieu of the required minimum physical heights of the antennas proper. Also, in other situations, it may...

47 CFR 73.186 - Establishment of effective field at one kilometer.

Code of Federal Regulations, 2011 CFR

2011-10-01

... radiation (not less than one wave length or 5 times the vertical height in the case of a single element, i.e... lieu of the required minimum physical heights of the antennas proper. Also, in other situations, it may...

Vestibular thalamus: Two distinct graviceptive pathways.

PubMed

Baier, Bernhard; Conrad, Julian; Stephan, Thomas; Kirsch, Valerie; Vogt, Thomas; Wilting, Janine; Müller-Forell, Wibke; Dieterich, Marianne

2016-01-12

To determine whether there are distinct thalamic regions statistically associated with either contraversive or ipsiversive disturbance of verticality perception measured by subjective visual vertical (SVV). We used modern statistical lesion behavior mapping on a sample of 37 stroke patients with isolated thalamic lesions to clarify which thalamic regions are involved in graviceptive otolith processing and whether there are distinct regions associated with contraversive or ipsiversive SVV deviation. We found 2 distinct systems of graviceptive processing within the thalamus. Contraversive tilt of SVV was associated with lesions to the nuclei dorsomedialis, intralamellaris, centrales thalami, posterior thalami, ventrooralis internus, ventrointermedii, ventrocaudales and superior parts of the nuclei parafascicularis thalami. The regions associated with ipsiversive tilt of SVV were located in more inferior regions, involving structures such as the nuclei endymalis thalami, inferior parts of the nuclei parafascicularis thalami, and also small parts of the junction zone of the nuclei ruber tegmenti and brachium conjunctivum. Our data indicate that there are 2 anatomically distinct graviceptive signal processing mechanisms within the vestibular network in humans that lead, when damaged, to a vestibular tone imbalance either to the contraversive or to the ipsiversive side. © 2015 American Academy of Neurology.

Biomechanical evaluation of implant-supported prosthesis with various tilting implant angles and bone types in atrophic maxilla: A finite element study.

PubMed

Gümrükçü, Zeynep; Korkmaz, Yavuz Tolga; Korkmaz, Fatih Mehmet

2017-07-01

The purpose of this study is to evaluate and compare bone stress that occurs as a result of using vertical implants with simultaneous sinus augmentation with bone stress generated from oblique implants without sinus augmentation in atrophic maxilla. Six, three-dimensional (3D) finite element (FE) models of atrophic maxilla were generated with SolidWorks software. The maxilla models were varied for two different bone types. Models 2a, 2b and 2c represent maxilla models with D2 bone type. Models 3a, 3b and 3c represent maxilla models with D3 bone type. Five implants were embedded in each model with different configurations for vertical implant insertion with sinus augmentation: Model 2a/Model 3a, 30° tilted insertion; Model 2b/Model 3b and 45° tilted insertion; Model 2c/Model 3c. A 150 N load was applied obliquely on the hybrid prosthesis. The maximum von Mises stress values were comparatively evaluated using color scales. The von Mises stress values predicted by the FE models were higher for all D3 bone models in both cortical and cancellous bone. For the vertical implant models, lower stress values were found in cortical bone. Tilting of the distal implants by 30° increased the stress in the cortical layer compared to vertical implant models. Tilting of the distal implant by 45° decreased the stress in the cortical bone compared to the 30° models, but higher stress values were detected in the 45° models compared to the vertical implant models. Augmentation should be the first treatment option in atrophic maxilla in terms of biomechanics. Tilted posterior implants can create higher stress values than vertical posterior implants. During tilting implant planning, the use of a 45° tilted implant results in better biomechanical performance in peri-implant bone than 30° tilted implant due to the decrease in cantilever length. Copyright © 2017 Elsevier Ltd. All rights reserved.

Improved-resolution real-time skin-dose mapping for interventional fluoroscopic procedures

NASA Astrophysics Data System (ADS)

Rana, Vijay K.; Rudin, Stephen; Bednarek, Daniel R.

2014-03-01

We have developed a dose-tracking system (DTS) that provides a real-time display of the skin-dose distribution on a 3D patient graphic during fluoroscopic procedures. Radiation dose to individual points on the skin is calculated using exposure and geometry parameters from the digital bus on a Toshiba C-arm unit. To accurately define the distribution of dose, it is necessary to use a high-resolution patient graphic consisting of a large number of elements. In the original DTS version, the patient graphics were obtained from a library of population body scans which consisted of larger-sized triangular elements resulting in poor congruence between the graphic points and the x-ray beam boundary. To improve the resolution without impacting real-time performance, the number of calculations must be reduced and so we created software-designed human models and modified the DTS to read the graphic as a list of vertices of the triangular elements such that common vertices of adjacent triangles are listed once. Dose is calculated for each vertex point once instead of the number of times that a given vertex appears in multiple triangles. By reformatting the graphic file, we were able to subdivide the triangular elements by a factor of 64 times with an increase in the file size of only 1.3 times. This allows a much greater number of smaller triangular elements and improves resolution of the patient graphic without compromising the real-time performance of the DTS and also gives a smoother graphic display for better visualization of the dose distribution.

Influence of implant number on the biomechanical behaviour of mandibular implant-retained/supported overdentures: a three-dimensional finite element analysis.

PubMed

Liu, Jingyin; Pan, Shaoxia; Dong, Jing; Mo, Zhongjun; Fan, Yubo; Feng, Hailan

2013-03-01

The aim of this study was to evaluate strain distribution in peri-implant bone, stress in the abutments and denture stability of mandibular overdentures anchored by different numbers of implants under different loading conditions, through three-dimensional finite element analysis (3D FEA). Four 3D finite element models of mandibular overdentures were established, using between one and four Straumann implants with Locator attachments. Three types of load were applied to the overdenture in each model: 100N vertical and inclined loads on the left first molar and a 100N vertical load on the lower incisors. The biomechanical behaviours of peri-implant bone, implants, abutments and overdentures were recorded. Under vertical load on the lower incisors, the single-implant overdenture rotated over the implant from side to side, and no obvious increase of strain was found in peri-implant bone. Under the same loading conditions, the two-implant-retained overdenture showed more apparent rotation around the fulcrum line passing through the two implants, and the maximum equivalent stress in the abutments was higher than in the other models. In the three-implant-supported overdenture, no strain concentration was found in cortical bone around the middle implant under three loading conditions. Single-implant-retained mandibular overdentures do not show damaging strain concentration in the bone around the only implant and may be a cost-effective treatment option for edentulous patients. A third implant can be placed between the original two when patients rehabilitated by two-implant overdentures report constant and obvious denture rotation around the fulcrum line. Copyright © 2012 Elsevier Ltd. All rights reserved.

Electroencephalographic markers of robot-aided therapy in stroke patients for the evaluation of upper limb rehabilitation.

PubMed

Sale, Patrizio; Infarinato, Francesco; Del Percio, Claudio; Lizio, Roberta; Babiloni, Claudio; Foti, Calogero; Franceschini, Marco

2015-12-01

Stroke is the leading cause of permanent disability in developed countries; its effects may include sensory, motor, and cognitive impairment as well as a reduced ability to perform self-care and participate in social and community activities. A number of studies have shown that the use of robotic systems in upper limb motor rehabilitation programs provides safe and intensive treatment to patients with motor impairments because of a neurological injury. Furthermore, robot-aided therapy was shown to be well accepted and tolerated by all patients; however, it is not known whether a specific robot-aided rehabilitation can induce beneficial cortical plasticity in stroke patients. Here, we present a procedure to study neural underpinning of robot-aided upper limb rehabilitation in stroke patients. Neurophysiological recordings use the following: (a) 10-20 system electroencephalographic (EEG) electrode montage; (b) bipolar vertical and horizontal electrooculographies; and (c) bipolar electromyography from the operating upper limb. Behavior monitoring includes the following: (a) clinical data and (b) kinematic and dynamic of the operant upper limb movements. Experimental conditions include the following: (a) resting state eyes closed and eyes open, and (b) robotic rehabilitation task (maximum 80 s each block to reach 4-min EEG data; interblock pause of 1 min). The data collection is performed before and after a program of 30 daily rehabilitation sessions. EEG markers include the following: (a) EEG power density in the eyes-closed condition; (b) reactivity of EEG power density to eyes opening; and (c) reactivity of EEG power density to robotic rehabilitation task. The above procedure was tested on a subacute patient (29 poststroke days) and on a chronic patient (21 poststroke months). After the rehabilitation program, we observed (a) improved clinical condition; (b) improved performance during the robotic task; (c) reduced delta rhythms (1-4 Hz) and increased alpha rhythms (8-12 Hz) during the resting state eyes-closed condition; (d) increased alpha desynchronization to eyes opening; and (e) decreased alpha desynchronization during the robotic rehabilitation task. We conclude that the present procedure is suitable for evaluation of the neural underpinning of robot-aided upper limb rehabilitation.

A method to differentiate the causes of stiff-knee gait in stroke patients.

PubMed

Campanini, I; Merlo, A; Damiano, B

2013-06-01

Stiff-knee gait (SKG) is a common abnormal gait pattern in patients after stroke characterized by insufficient knee flexion (KF) during swing. Overactivity of the rectus femoris (RF) is considered the primary cause of SKG. Inadequate push-off has been indicated as an additional cause in the recent literature, as KF depends on knee flexion velocity in preswing (KFV). We used the peak of vertical acceleration of the malleolus (PMVA) as a kinematic-based indirect measure of push-off and studied its relationship with KF and KFV in a sample of 20 healthy subjects walking fast (v = 95 ± 5%heights(-1)), at self-selected speed (v = 74 ± 5%heights(-1)), slow (v = 54 ± 6%heights(-1)) and very slow (v = 38 ± 5%heights(-1)) and in a sample of 52 stroke patients with SKG (age 60 ± 11, v = 20 ± 11%heights(-1)). In healthy subjects PMVA occurred before knee flexion acceleration (p<0.001) and hip flexion acceleration (p<0.001). KF appeared as a bottom-up mechanism driven by the ankle push-off. From a regression analysis, the PMVA-KFV cause-effect relationship resulted strictly linear, with R(2) = 0.967, KFV = 0+7.1×PMVA, P<0.0001. Data from SKG patients were compared to this normal cause-effect model. For 44/52 patients the reduced KFV was combined with lack of push-off. Data from 8/52 patients only were statistically outside the 95%CI of the model, thus requiring for a braking mechanism to explain KFV reduction. In stroke adults of our sample the push-off impairment (85% of cases) and not the inappropriate knee extension moment produced by the thigh muscles was the primary cause of SKG. This result could explain the low average efficacy (<10°) of focal and surgical treatments at the quadriceps. The presented model could be used to differentiate the primary cause of SKG between inadequate push-off and braking activity of the thigh muscles, thus increasing the effectiveness of the selected treatment. Copyright © 2013 Elsevier B.V. All rights reserved.