Motion

For tumor tracking, a correlation model is used to estimate internal tumor position based on external surrogate motion. When patients experience an internal/external surrogate drift, an update of the correlation model is required to continue tumor tracking. In this study, the accuracy of the internal tumor position estimation for both the clinical available update at discrete points in time (rebuild) and an in-house developed non-clinical online update approach was investigated. A dynamic phantom with superimposed baseline drifts and 14 SBRT patients, treated with real-time tumor tracking (RTTT) on the Vero system, were retrospectively simulated for three update scenarios, respectively no update, clinical rebuild and 0.5 Hz automated online update of the correlation model. By comparing the target positions based on 0.5 Hz verification X-ray images with the estimated internal tumor positions regarding all three update scenarios, 95th percentile modeling errors (ME95), incidences of f...

Advances in 99mTc-based radiopharmaceuticals and multiple-detector gantries have the potential to increase the significance of patient motion on the diagnostic integrity of myocardial perfusion SPECT acquisitions. An experimental study was used to evaluate the effect of various patient motions on the diagnostic integrity of myocardial perfusion SPECT data using 522 motion simulations generated from a technically and diagnostically normal dataset. Of studies with induced motion, 21.7% of simulated motion demonstrated motion-induced artifacts. Abrupt motion resulted in artifacts for 52.6% of studies, whereas bounce motion resulted in artifacts in 6.8% of studies. The locations where motion resulted in the most studies with artifacts were at 45 degrees (36.1%) and 75 degrees (32.4%). No statistical difference was demonstrated between single, dual-, and triple-head configurations. Combining these results with those of the clinical evaluation of incidence indicates that patient motion du...

Despite advances in (99m)Tc-based radiopharmaceuticals and multiple-detector gantries, patient motion in myocardial perfusion SPECT acquisitions is still problematic and may produce artifacts that mimic coronary artery disease. A prospective cross-sectional study of 800 myocardial perfusion SPECT studies performed with (99m)Tc-based radiopharmaceuticals at 3 private nuclear medicine sites was used to determine the incidence, type, and location of visually detectable motion. The rotating cinematic display and sinograms of the ungated datasets were visually assessed by 2 experienced technologists unaware of the other observer's responses and the clinical outcome. Among the 800 studies analyzed, 36% contained visually detectable motion. Motion was seen on 31.5% of rest studies, compared with 40.5% of stress studies (P = 0.004). The most common type of motion detected was multiple bounce, which represented 47.6% of motion. Left anterior oblique and anterior were the most common spec...

Sedimentary basins increase the damaging effects of earthquakes by trapping and amplifying seismic waves. Simulations of seismic wave propagation in sedimentary basins capture this effect; however, there exists no method to validate these results for earthquakes that have not yet occurred. We present a new approach for ground motion prediction that uses the ambient seismic field. We apply our method to a suite of magnitude 7 scenario earthquakes on the southern San Andreas fault and compare our ground motion predictions with simulations. Both methods find strong amplification and coupling of source and structure effects, but they predict substantially different shaking patterns across the Los Angeles Basin. The virtual earthquake approach provides a new approach for predicting long-period strong ground motion.

Considering as the point of departure an examination of the concept of stillness - as it is present and perceived in our reality - my thesis research gradually unfolds the world of frame-by-frame drawn animation, exploring how stillness functions in an animated moment.

Through these explorations, my research encounters a paradox in the field of frame-by-frame animation: namely, that movement is composed from still images.

Proceeding from this paradox, I take up questions concerning the ways in which the spectator perceives these lingering moments in drawn animated films, and how they resonate intuitive emotional reactions.
My thesis poses a final connection that interlaces theoretical aspects taken up in this study and my personal animating practice, and is represented through my graduation film η μητέρα μου, η θάλασσα (my mother, the sea). This work investigates physical tools - corporeal apparatuses - that enabled me to capture the movement of my transitional stillness through my emotional journey.

This study, with a top T-52 class athlete, determines the relationship between stroke frequency (SF) and push time (PT) and wheelchair velocity (Wv) using different handrim diameters (HD) and the effect of different HDs on the athlete’s heart rate (HR) and blood lactate (LACT) at competition speeds. Wv shows a linear-direct relationship with SF but a linear-inverse relationship with PT (p < .001 in both cases). Using bigger handrims (0.37 m instead of 0.36 m), SF increases 6%, while PT decreases 27% (at 24 Km·h–1). HR (p < .0001) increases with Wv and is also affected by HD with differences between the 0.34 m—0.36 m handrim group (lower values) and the 0.37 m handrim (higher values). Significant interaction (p < .0001) is identified between HD and Wv. LACT results seem to follow the same direction as HR. This methodology helped the athlete to choose the optimum HD, and his achievements (some world records) indicate that HD optimization could be highly profitable in sport te...

The chemotactic movement of decanol droplets in aqueous solutions of sodium decanoate in response to concentration gradients of NaCl has been investigated. Key parameters of the chemotactic response, namely the induction time and the migration velocity, have been evaluated as a function of the sodium decanoate concentration and the NaCl concentration gradient. The ability of the decanol droplets to migrate in concentration gradients has been demonstrated not only in a linear chemotactic assay but also in a topologically complex environment. Additionally, the ability to reverse the direction of movement repeatedly, to carry and release a chemically reactive cargo, to select a stronger concentration gradient from two options, and to initiate chemotaxis by an external temperature stimulus have been demonstrated.

This study assessed accuracy of surface and underwater 3D reconstruction of a calibration volume with and without homography. A calibration volume (6000 × 2000 × 2500 mm) with 236 markers (64 above and 88 underwater control points—with 8 common points at water surface—and 92 validation points) was positioned on a 25 m swimming pool and recorded with two surface and four underwater cameras. Planar homography estimation for each calibration plane was computed to perform image rectification. Direct linear transformation algorithm for 3D reconstruction was applied, using 1600000 different combinations of 32 and 44 points out of the 64 and 88 control points for surface and underwater markers (resp.). Root Mean Square (RMS) error with homography of control and validations points was lower than without it for surface and underwater cameras (P≤0.03). With homography, RMS errors of control and validation points were similar between surface and underwater cameras (P≥0.47). Without homography,...

We study the dynamics of inertial particles in three-dimensional incompressible maps, as representations of volume-preserving flows. The impurity dynamics has been modeled, in the Lagrangian framework, by a six-dimensional dissipative bailout embedding map. The fluid-parcel dynamics of the base map is embedded in the particle dynamics governed by the map. The base map considered for the present study is the Arnold-Beltrami-Childress (ABC) map. We consider the behavior of the system both in the aerosol regime, where the density of the particle is larger than that of the base flow, as well as the bubble regime, where the particle density is less than that of the base flow. The phase spaces in both the regimes show rich and complex dynamics with three types of dynamical behaviors--chaotic structures, regular orbits, and hyperchaotic regions. In the one-action case, the aerosol regime is found to have periodic attractors for certain values of the dissipation and inertia parameters. For ...

An active swimmer can tow a passive cargo by binding it to form a self-propelling dimer. The orientation of the cargo relative to the axis of the active dimer's head is determined by the hydrodynamic interactions associated with the propulsion mechanism of the latter. We show how the tower-cargo angular configuration greatly influences the dimer's diffusivity and, therefore, the efficiency of the active swimmer as a micro-towing motor.

Proton MR spectroscopy is a powerful noninvasive method that enables measurement of certain brain metabolites in healthy subjects and patients with diseases. A major difficulty with clinical and research applications of in vivo proton MR spectroscopy is the variability of metabolite concentrations, especially in regions with substantial physiologic motion. In our preliminary evaluation, we tested the hypothesis that physiologic brain motion leads to lower mean metabolite concentrations and higher SDs for the measured metabolite concentrations.