BACKGROUND: Patient movement has been considered an important source of errors in cardiac PET. This study was aimed at evaluating the effects of such movement on myocardial blood flow (MBF) and perfusable tissue fraction (PTF) measurements in intravenous (15)O-water PET. METHODS: Nineteen (15)O-water scans were performed on ten healthy volunteers ...

Loops in proteins that connect secondary structures such as alpha-helix and beta-sheet, are often on the surface and may play a critical role in some functions of a protein. The mobility of loops is central for the motional freedom and flexibility requirements of active-site loops and may play a critical ...

MR scans are sensitive to motion effects due to the scan duration. To properly suppress artifacts from nonrigid body motion, complex models with elements such as translation, rotation, shear, and scaling have been incorporated into the reconstruction pipeline. However, these techniques are computationally intensive and difficult to implement for online ...

How does the visual system assign the perceived position of a moving object? This question is surprisingly complex, since sluggish responses of photoreceptors and transmission delays along the visual pathway mean that visual cortex does not have immediate information about a moving object's position. In the flash-lag effect (FLE), a ...

Purpose: Deformable registration generally relies on the assumption that the sought spatial transformation is smooth. Yet, breathing motion involves sliding of the lung with respect to the chest wall, causing a discontinuity in the motion field, and the smoothness assumption can lead to poor matching accuracy. In response, alternative registration ...

This paper studies the problem of 3D-rigid motion invariant texture discrimination for discrete 3D-textures that are spatially homogeneous by modeling them as stationary Gaussian random fields. The latter property and our formulation of a 3D-rigid motion of a texture reduce the problem to the study of 3D-rotations of discrete textures. ...

Animals that use echolocation (biosonar) listen to acoustic signals with a large range of intensities, because echo levels vary with the fourth power of the animal's distance to the target. In man-made sonar, engineers apply automatic gain control to stabilize the echo energy levels, thereby rendering them independent of distance ...

We found that specific nuclear motion along low-frequency modes is effective in coupling electronic states and that this motion prevail in some small molecules. Thus, in direct contradiction to what is expected based on the standard models, the internal conversion process can proceed faster for smaller molecules. Specifically, we focus ...

In this study, heterodyne detection is adopted to measure the velocity of a target simulated by a rapidly rotating plate by using a mode-locked pulse laser as the resource. The coherent beat frequency of the signal light reflected by target and local oscillation light occurred on the surface of the ...

We examined subjects' behavior when they tracked periodic oscillating targets moving along a randomly oriented ramp with the head free to move. This study focuses on the effect of target motion direction on pursuit performance and on head tracking strategies used by human subjects to coordinate eye and head movements. ...

To track highly directional echolocation clicks from odontocetes, passive hydrophone arrays with small apertures can be used to receive the same high frequency click on each sensor. A four-hydrophone small-aperture array was coupled to an autonomous acoustic recorder and used for long-term tracking of high-frequency odontocete sounds. The instrument was ...

Bottlenose dolphins (Tursiops truncatus) wore opaque suction cups over their eyes while stationing behind an acoustically opaque door. This put the dolphins in a known position and orientation. When the door opened, the dolphin clicked to detect targets. Trainers specified that Dolphin S emit a whistle if the target was ...

Teun Bousema and colleagues argue that targeting malaria "hotspots" is a highly efficient way to reduce malaria transmission at all levels of transmission intensity.

Chronic circadian disturbance, a condition of desynchronization between endogenous clock and environmental light-dark (LD) cycle, is known to cause adverse physiological changes including mortality. However, it is yet unclear whether these consequences result from disturbance of endogenous clock or condition of the LD cycle per se. To address this issue, ...

Vicious Brownian motion is a diffusion scaling limit of Fisher's vicious walk model, which is a system of Brownian particles in one dimension such that if two motions meet they kill each other. We consider the vicious Brownian motions conditioned never to collide with each other and call it noncolliding ...

Diatoms are photoautotrophic organisms capable of growing on a variety of inorganic and organic nitrogen sources. Discovery of a complete urea cycle in diatoms was surprising, as this pathway commonly functions in heterotrophic organisms to rid cells of waste nitrogen. To determine how the urea cycle is integrated into cellular ...

Steady-state visual evoked potential-based brain computer interfaces (SSVEP-based BCIs) have generated significant interest due to their high information transfer rate (ITR). Due to the amplitude-frequency characteristic of SSVEP, the flickering frequency of an SSVEP-based BCI is typically lower than 20 Hz to achieve high signal-to-noise ratio (SNR). However, a visual ...

The photodamage process of photosystem II by strong illumination was investigated by examining the herbicide effects on the photoinactivation of redox cofactors. O(2)-evolving photosystem II membranes from spinach in the absence of herbicide and in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and bromoxynil were subjected to strong white-light illumination at 298K, ...

The International Society of Biomechanics detailed the recommendations for 3D kinematics of intervertebral movements (Wu, et al. 2002. J Biomech. 35:543-548), but does not specify how to adapt this proposal to describe the kinematics of the cervical spine, between the head and the thorax. The analysis of the literature shows ...

Recombination of the primary radical pair of Photosystem II (PSII) of photosynthesis may produce the triplet state of the primary donor of PSII. Triplet formation is potentially harmful because chlorophyll triplets can react with molecular oxygen to produce the reactive singlet oxygen ((1) O(2) ). The yield of (1) O(2) ...

Rinalduzzi S, Cipriani AM, Capozza M, Accornero N. Postural responses to low-intensity, short-duration, galvanic vestibular stimulation as a possible differential diagnostic procedure. Acta Neurol Scand: 2011: 123: 111-116. © 2010 The Authors Journal compilation © 2010 Blackwell Munksgaard. Objectives -  In this study we investigated the effect of polarity-related differences in ...

Under twilight viewing conditions, hypoxia, equivalent to breathing air at 3048 m (10,000 ft), compromises low contrast acuity, dynamic contrast sensitivity, and chromatic sensitivity. Selected past experiments have been repeated under milder hypoxia, equivalent to altitude exposure below 2438 m (8000 ft), to further define the influence of oxygenation state ...

We demonstrate the Thatcher effect in biological-motion displays and show that it is primarily a result of the moving, and not static, cues in the display.

It is well known in the literature of haptic supplementation that a "light touch" (LT) with the index finger on a stable surface increases postural stability. In view of potential application in the domain of mobility aids, it should however be demonstrated that haptic supplementation is effective even when provided ...

Developed from traditional Chinese martial arts, Tai Chi exercise includes different forms and interactive Push Hands but biomechanical analyses have focused on the former only. To analyse the techniques of Push Hands, an experienced master was asked to defend pushing by four opponents. Movements were videotaped and digitized using a ...

The goal of this work is to analyze postural control in Ehlers-Danlos syndrome (EDS) participants in time and frequency domain. This study considered a pathological group composed by 22 EDS participants performing a postural test consisting in maintaining standing position over a force platform for 30s in two conditions: open ...

A spectrofluorometer equipped with a highly sensitive near-IR InGaAs detector was used for the direct visualization of singlet oxygen emission at 1268 nm in olive oil during light irradiation with various different wavelengths. The virgin olive oil in methylene chloride (20% w/v, oxygen saturated) was irradiated at the 301, 417, ...

In this paper a novel electrically actuated parallel robot with three degrees-of-freedom (3 DOF) for dynamic postural studies is presented. The design has been described, the solution to the inverse kinematics has been found, and a numerical solution for the direct kinematics has been proposed. The workspace of the implemented ...

The purpose of this study was to investigate the effect of masticating chewing gum on postural stability during upright standing. To address this issue, 12 healthy subjects performed quiet standing on a force platform for the posturography study. The subjects were instructed to stand as stable as possible on the ...

During leg flexion from erect posture, postural stability is organized in advance during "anticipatory postural adjustments" (APA). During these APA, inertial forces are generated that propel the centre of gravity (CoG) laterally towards stance leg side. This study examined how fear of falling (FoF) may influence this anticipatory postural control ...

OBJECTIVES: The purposes of this study are to assess the relationship of the center of pressure (CoP) displacement parameters along the mediolateral and anteroposterior axes to whole-body oscillations about the vertical axis during single or double leg upright stance and to determine whether sensory deprivation and stance modify balance stability ...

Nest building is an important part of maternal behavior in domestic pigs. The aim of the study was to assess the effect of nesting material sawdust vs. straw on sow behavior 24 h before and after birth of the first piglet (BFP) and piglet production. Sows, housed in farrowing crates, ...

Vision can improve bipedal upright stability during standing and locomotion. However, during locomotion, vision supports additional behaviors such as gait cycle modulation, navigation, and obstacle avoidance. Here, we investigate how the multiple roles of vision are reflected in the dynamics of trunk control as the neural control problem changes from ...

Prolonged occupational standing has previously been associated with low back pain (LBP) development. The immediate effects of a bout of prolonged standing on subsequent functional movement performance have not been investigated. It is possible that including a period of prolonged standing may have acute, detrimental effects. The purpose of the ...

OBJECTIVE: To investigate whether 2 different mechanisms of ankle joint taping ([1] lateral subtalar sling or [2] fibular repositioning) can enhance actual and perceived dynamic postural stability in participants with chronic ankle instability (CAI). DESIGN: Laboratory-based repeated-measures study. SETTING: University biomechanics laboratory. PARTICIPANTS: Participants (n=16) with CAI. INTERVENTIONS: Participants performed ...

People with multiple sclerosis (MS) often have poor postural control, which likely underlies their increased risk of falls. Based on several studies of balance and gait in MS, it appears that the primary mechanisms underlying the observed changes are slowed somatosensory conduction and impaired central integration. This review of the ...

Humans and other species are unable to stand perfectly still; their bodies continuously sway during stance even during concentrated efforts to avoid such movement. Traditionally, this phenomenon has been viewed as an inability of the central nervous system (CNS) to maintain perfect equilibrium because of its reliance on feedback from ...

The aim was to describe diaphragmatic behavior during postural limb activities and examine the ventilatory and stabilizing functions of the diaphragm. Thirty healthy subjects were examined in the supine position using a dynamic MRI system assessed simultaneously with specialized spirometric readings. The diaphragmatic excursions (DEs) were measured at three diaphragmatic ...

Evidence suggesting that the brain has specialized mechanisms for processing human bodies include the discovery of body-selective brain areas and the behavioral body inversion effect (BIE). Interestingly, the BIE (worse discrimination of inverted vs upright bodies) disappears for headless bodies, implying a critical role of the head in this effect. ...

This study defines the limits of stability in sitting, and quantitatively assesses two measures of postural control relative to these limits. Young, healthy subjects sat, feet unsupported, on an elevated force plate. The limits of stability were determined by a least square fit of an ellipse to the center of ...

Understanding how the human body responds to unexpected force perturbations during quiet sitting is important to the science of motor behavior and the design of neuroprostheses for sitting posture. In this study, the performance characteristics of the neck and trunk in healthy individuals were assessed by measuring the kinematic responses ...

To assess vestibular influences on recovery of balance during sudden falls, we measured the postural responses of five healthy subjects to a hold and release perturbation coupled with galvanic vestibular stimulation (GVS). Two electrode pairs were located with the anterior electrode of each pair over the mastoid process and the ...

Integration of sensory and motor inputs has been shown to be impaired in appendicular muscles and joints of Parkinson's disease (PD) patients. As PD advances, axial symptoms such as gait and balance impairments appear, which often progresses to complete inability stand or walk unaided. The current study evaluates kinesthesia in ...

Multisensory reweighting (MSR) is an adaptive process that prioritizes the visual, vestibular, and somatosensory inputs to provide the most reliable information for postural stability when environmental conditions change. This process is thought to degrade with increasing age and to be particularly deficient in fall-prone versus healthy older adults. In the ...

Musculoskeletal complaint rates are high among those performing low-level static exertions (LLSEs), such as computer users. However, our understanding of the causal mechanisms is lacking. It was hypothesized that myofascial trigger point (MTrP) development might be one causal mechanism to help explain these complaints and that static postural and visual ...

To evaluate the effect of early systematic soccer training on postural control we measured center-of-pressure (COP) variability, range, mean velocity and frequency in bipedal quiet stance with eyes open (EO) and closed (EC) in 44 boys aged 13 (25 boys who practiced soccer for 5-6 years and 19 healthy boys ...

Posture and movement are fundamental, intermixed components of motor coordination. Current approaches consider either that 1) movement is an active, anticipatory process and posture is a passive feedback process or 2) movement and posture result from a common passive process. In both cases, the presence of a passive component renders ...

The causes of the interindividual differences (IDs) in how we perceive and control spatial orientation are poorly understood. Here, we propose that IDs partly reflect preferred modes of spatial referencing and that these preferences or "styles" are maintained from the level of spatial perception to that of motor control. Two ...

The aim of this study was to determine the effects of video playback speed on posture matching reliability of the distal upper extremity. Video is frequently used in ergonomic assessments, yet there remains a need to determine the effects of viewing speed on posture observations. Participants were 7 graduate students ...

It has been recently argued that human bodies are processed by a specialized processing mechanism. Central evidence was that body inversion reduces recognition abilities (body inversion effect; BIE) as much as it does for faces, but more than for other objects. Here we showed that the BIE is markedly reduced ...