Tachycardia and hypertension enhance tracer efflux from the spinal cord

Background Disruption of cerebrospinal fluid (CSF)/interstitial fluid (ISF) exchange in the spinal cord is likely to contribute to central nervous system (CNS) diseases that involve abnormal fluid accumulation, including spinal cord oedema and syringomyelia. However, the physiological factors that govern fluid transport in the spinal cord are poorly understood. The aims of this study were to determine the effects of cardiac pulsations and respiration on tracer signal increase, indicative of molecular movement following infusion into the spinal cord grey or white matter. Methods In Sprague Dawley rats, physiological parameters were manipulated such that the effects of spontaneous breathing (generating alternating positive and negative intrathoracic pressures), mechanical ventilation (positive intrathoracic pressure only), tachycardia (heart atrial pacing), as well as hypertension (pharmacologically induced) were separately studied. Since fluid outflow from the spinal cord cannot be directly measured, we assessed the molecular movement of fluorescent ovalbumin (AFO-647), visualised by an increase in tracer signal, following injection into the cervicothoracic spinal grey or white matter. Results Tachycardia and hypertension increased AFO-647 tracer efflux, while the concomitant negative and positive intrathoracic pressures generated during spontaneous breathing did not when compared to the positive-pressure ventilated controls. Following AFO-647 tracer injection into the spinal grey matter, increasing blood pressure and heart rate resulted in increased tracer movement away from the injection site compared to the hypotensive, bradycardic animals (hypertension: p = 0.05, tachycardia: p < 0.0001). Similarly, hypertension and tachycardia produced greater movement of AFO-647 tracer longitudinally along the spinal cord following injection into the spinal white matter (p < 0.0001 and p = 0.002, respectively). Tracer efflux was strongly associated with all blood vessel types. Conclusions Arterial pulsations have profound effects on spinal cord interstitial fluid homeostasis, generating greater tracer efflux than intrathoracic pressure changes that occur over the respiratory cycle, demonstrated by increased craniocaudal CSF tracer movement in the spinal cord parenchyma.

Tracer vertical movement and its affecting factors in karst soil profiles using the simulated leaching method

&lt;p&gt;Soil erosion is a severe issue in Southwest China due to complex karst geomorphology and excessive farming activities. It is also difficult to observe and evaluate using traditional research methods. Fortunately, as a supplement to traditional methods, the &lt;sup&gt;137&lt;/sup&gt;Cs tracing technique has strong potential to monitor and evaluate soil loss in karst regions. However, &lt;sup&gt;137&lt;/sup&gt;Cs might move downward with tiny particles under adequate rainfall conditions. This is critical because it directly affects accuracy of using the &lt;sup&gt;137&lt;/sup&gt;Cs conversion model to evaluate soil erosion. Thus, in our study, in order to explore whether tracers actually moved vertically and to evaluate the movement distance and the factors influencing the movement, magnetic powder (Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;) and rare earth oxides (CeO&lt;sub&gt;2 &lt;/sub&gt;and La&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;) were used as the substitute tracers under different conditions (rainfall and leaching area) of a simulated leaching experiment, which possess similar properties as &lt;sup&gt;137&lt;/sup&gt;Cs and have no toxicity problems in humans and the environment. The results showed that tracers moved downward 6 cm when water was added to simulate 1-10-year rainfall conditions and 8 cm when water was added to simulate 15-20-year rainfall conditions. The movement distance of tracers increased slowly with increasing water input, and the concentration of the tracers that moved related indirectly to the leaching area. Tracer movement at the edge of the simulated profile was affected by tracer type and concentration since there was no transition layer between soil and plastic column. Our field observations in two karst watersheds showed that ignoring the vertical movement of tracer can cause the overestimation of soil loss amount by 6.90% and 22.22% respectively. This study proved that in the karst area of Southwest China with abundant rainfall, &lt;sup&gt;137&lt;/sup&gt;Cs would move vertically, and the soil loss will be overestimated if the vertical movement distance of the tracer is ignored.&lt;/p&gt;

Inverse Kinematics Hand Tracking Method To Create 3D Animation

Abstract— 3D animation production stage is growing.Many new techniques apply to each production process. Not a lot of animation production that uses new techniques, thus allowing production houses to perform such techniques as one way to improve the quality of animation production in the country. One technique that is often used in producing 3D animation is the motion tracking. Hand tracking technique is one of motion tracking technique that focuses more on handorgan. Motion Tracking is a process in getting the rackerfrom marker a footage that has been paired marker. Markers generated from the motion tracking process can be referred to as a tracer. Tracer can be connected with 3D objects that have complete modeling and rigging. So it can generate an animation of the tracer movement that was hung with a 3d bone modeling. Using the inverse kinematics method approach is done to improve when the animation produced is more controlled movement and by adding DOF (Degree OfFreedom) in every space of motion model that has beenconnected tracer with bone (bone) riggingnya avoidanimation movement out of the path.

Vertical and lateral subsurface preferential flow along an agricultural catena

Despite all efforts, agricultural contaminants remain at alarming concentrations in Quebec surface waters. Preferential flow (PF) of soluble contaminants has been suggested as a contributing factor but has not been specifically studied in the humid climate of eastern Canadian soils. Three tracers were surface applied on plots along a catena on a loamy sand under intensive agricultural production in Beauce, Quebec. Tracer distribution in soil profiles was monitored three times over a 12-month period. At the summit, finger flow rapidly transported tracers into the subsurface. The subsurface preferential lateral flow rapidly brought the tracers downslope. Narrow points of preferential seepage and discharge and underground lateral PF were observed at the footslope. The summit and the backslope of the catena showed strong vertical and lateral subsurface PF, which made their contribution to subsurface tracer movement toward surface water equal to or greater than that of the footslope, in part because of the hydrological connectivity between summit, backslope, and surface water. PF and matrix flow were both significant in all parts of the catena. Therefore, all parts of a catena, even those far from surface water, should be considered when evaluating potential belowground contaminant transport toward surface water.