Sonoporation with phase-shift nanoemulsions: an in vitro study

Acoustic cavitation (i.e. acoustically stimulated microbubble activity) has gained interest in the biomedical community due to its ability to locally concentrate mechanical forces inside the body. Biological structures in close proximity experience stresses that temporally disrupt their normal function and allow passage of material that would otherwise be impermeable. Examples include blood-brain barrier disruption, enhanced penetration of drugs into tumors, disruption of the blood vessel endothelium, and permeabilization of cell membranes (i.e. sonoporation). The goal of this thesis was to investigate a new class of acoustic cavitation nuclei for sonoporation called phase-shift nanoemulsions (PSNE). Ultrasound can be used to nucleate, or phase-shift PSNE into microbubbles with a process termed acoustic droplet vaporization (ADV). Specifically, the focus was to use PSNE for delivery of small interfering RNA (siRNA) to an in vitro cell suspension using sonoporation. Small interfering RNA is an exogenous RNA molecule and has gained increased attention due to its ability to knockdown specific proteins central to disease progression. Results showed that siRNA delivery with PSNE is possible with high uptake efficiency (i.e. ratio of the number of cells with uptake to the number of cells originally). Uptake was highly dependent on the amount of acoustic cavitation activity generated from PSNE. The acoustic emissions from individual PSNE were explored to understand the microbubble dynamics following ADV. Results showed that PSNE immediately undergo an explosive growth and collapse at the ADV threshold, and the maximum size of the microbubble depends on the ultrasound frequency. This led to the hypothesis that the sonoporation efficiency with PSNE is governed by the choice of frequency. Lower frequencies were shown to expand microbubbles to larger maximum radii, which in turn caused more energetic collapses leading to cell death. This explains the lower uptake efficiencies at lower frequencies (39.45% at 1 MHz and 46.62% at 2.5 MHz), compared to the relatively high uptake efficiency at 5 MHz (66.81%). In general, uptake efficiencies > 50% have rarely been achieved with current sonoporation methods and these results are a significant improvement. PSNE could also serve as a unique platform for numerous other therapeutic ultrasound applications that utilize the mechanical effects of acoustic cavitation. The frequency-dependent control over the microbubble dynamics following ADV could provide a way to tune the level of stress experienced by biological structures.2017-02-17T00:00:00

International Air Transport Association Vision 2050 Report Assessment

The International Air Transport Associations report Vision 2050 report addresses how the aviation industry members participating in the Vision 2050 will work towards meeting combined established goals, which include improving and creating a consistent profitability across the industry, focusing on the consumer, producing an improved global infrastructure, and advancements in technology. Understanding prospective future air transport volumes will help aviation industry participants plan now, how to meet the future needs for training a workforce, working with the government today on policy changes that may be needed and how to expand airline and airport operations to meet needs. The importance of aviation on a global scale and meeting initiatives could be beneficial to many areas within the aviation communities

D-Brane Dynamics and NS5 Rings

We consider the classical motion of a probe D-brane moving in the background geometry of a ring of NS5 branes, assuming that the latter are non-dynamical. We analyse the solutions to the Dirac-Born-Infield (DBI) action governing the approximate dynamics of the system. In the near horizon (throat) approximation we find several exact solutions for the probe brane motion. These are compared to numerical solutions obtained in more general cases. One solution of particular interest is when the probe undergoes oscillatory motion through the centre of the ring (and perpendicular to it). By taking the ring radius sufficiently large, this solution should remain stable to any stringy corrections coming from open-strings stretching between the probe and the NS5-branes along the ring.Comment: 17 pages, Latex, 8 figures; References adde

Reliability and validity of the running anaerobic sprint test (RAST) in soccer players.

To investigate the validity and relative and absolute reliability of the Running Anaerobic Sprint Test (RAST) in ama teur soccer players. Cross-sectional experimental design with an element of repeated measures. Twenty three males completed the RAST on two occasions and a Wingate test (WAnT) as criterion measure of anaero bic power. Criterion validity for the RAST was strong for peak power (r = 0.70, p < 0.001) and average power (r = 0.60, p = 0.002); however, the RAST significantly underestimated peak power compared to WAnT. The RAST showed very good relative reli ability for average power, ICC = 0.88 and good relative reliability for peak power, ICC = 0.72. Assessment of absolute reliability highlighted that although when averaged across a group, test and re-test scores will be similar, when monitoring individuals an individual's retest score may range between 0.81 and 1.2 times the original value for peak power and between 0.9 and 1.16 for average power. The RAST is a practicable field test to estimate levels of average anaerobic power. However, the results show that the RAST is not sensitive enough to detect strongly individual changes below 20 % and is therefore not recommended to continually monitor an individual's anaerobic power. Also, if true measures of peak power are required the RAST test is limited