Characterisation of adherent microbubbles for molecular targeted ultrasound

Molecular imaging is a field of medicine which can offer great potential for both diagnostic and therapeutic purposes. Within this field contrast enhanced ultrasound displays the possibility of making molecular imaging a cost effective viable tool in an increasingly diverse set of clinical situations. One of the current challenges associated with this technique is how one differentiates the signal for adherent microbubbles from those produced by the bulk non-adherent population. The first part of this thesis acoustically examines the response of single microbubbles under the effects of adhesion and compares the response observed with that of the MBs non-adherent counterpart. It was found experimentally that differences could be observed in both the 2nd harmonic signals generation and in the stability over repeated exposure. These differences could be utilised as the basis for discretisation imaging strategies. The second section of this thesis attempts to characterize these differences in terms of current theoretical models. A more comprehensive modelling strategy is utilised for the fitting of increasingly complex theoretical models. Good agreement was found with the outputs of this fitting procedure with previously reported parameters. Further detail could also be observed in the form of various size/resonance effects which have not previously been reported. There was little observed difference between the parameters extracted for the adherent and non-adherent MBs although it was suggested that the effective elasticity of an adherent MB could be elevated in comparison to its non-adherent counterpart in the region of resonance. Efforts will be required to control and account for some of the variability observed in MB response before this can be stated definitively however.Open Acces

Synthesis and Analysis of Copper Beta-Diketonate Complexes

This research addresses the synthesis and characterization of Cu(II) complexes of silicon-based multidentate β-diketonate ligands. The possible products of the synthesis include (where L represents the coordinated ligand) cube Cu12L8, decahedron Cu24L16, and dodecahedron Cu30L20. This study aims to determine the structure of these discrete molecules, which may have applications in drug delivery, fuel storage, and chemical retention. Different techniques were involved in the characterization of Cu(II) complexes: Electrospray Ionization Time of Flight Mass Spectrometry (ESI-TOF MS), Atomic Force Microscopy (AFM) and Analytical Ultracentrifugation (AUC). In ESI-TOF MS, the exact mass of the molecules was attempted to be determined by experimenting if multiply charged ions could occur with these complexes. Although no multiply charged ion peaks were discovered, different experimental conditions yielded different ESI-TOF MS spectra. Additionally in ESI-TOF MS, peaks having large m/z values containing copper atoms were discovered. In AFM studies, heights of multiple copper complexes were measured to see if the discrete molecules of cube (2 nm), decahedron (3.5-4.5 nm), and dodecahedron (5 nm) could be identified. In creating an AFM histogram, the frequency of heights could be used to determine what kind of complexes were being formed and in what percentage. In the studies conducted, there were common occurrences of the samples at or around the heights of the projected structures (e.g. cube, decahedron, and dodecahedron). Additionally, there was a substantial occurrence of measured heights (i.e. 8 nm and 10 nm) that indicated possible aggregation of the discrete molecules. The AUC technique was used to determine whether the samples contained a pure compound or a mixture of discrete molecules, and also to estimate their molecular weight. What was found in the AUC studies of the Cu(II) complexes of silicon-based multidentate β-diketonate ligands were molecular weights similar to the empirical formula of the molecules (i.e. Cu3(MeSi(phac)3)2: 1322.07 g/mol; Cu3(MeSi(phpr)3)2: 1567.80 g/mol) and samples that were polydisperse. No evidence from AUC showed the discovery of compounds which had molecular weights similar to the proposed polyhedra. The numbers are based on assumed densities of 1.138 g/mL

Repositioning Tiered HotSpot Execution Performance Relative to the Interpreter

Although the advantages of just-in-time compilation over traditional interpretive execution are widely recognised, there needs to be more current research investigating and repositioning the performance differences between these two execution models relative to contemporary workloads. Specifically, there is a need to examine the performance differences between Java Runtime Environment (JRE) Java Virtual Machine (JVM) tiered execution and JRE JVM interpretive execution relative to modern multicore architectures and modern concurrent and parallel benchmark workloads. This article aims to fill this research gap by presenting the results of a study that compares the performance of these two execution models under load from the Renaissance Benchmark Suite. This research is relevant to anyone interested in understanding the performance differences between just-in-time compiled code and interpretive execution. It provides a contemporary assessment of the interpretive JVM core, the entry and starting point for bytecode execution, relative to just-in-time tiered execution. The study considers factors such as the JRE version, the GNU GCC version used in the JRE build toolchain, and the garbage collector algorithm specified at runtime, and their impact on the performance difference envelope between interpretive and tiered execution. Our findings indicate that tiered execution is considerably more efficient than interpretive execution, and the performance gap has increased, ranging from 4 to 37 times more efficient. On average, tiered execution is approximately 15 times more efficient than interpretive execution. Additionally, the performance differences between interpretive and tiered execution are influenced by workload category, with narrower performance differences observed for web-based workloads and more significant differences for Functional and Scala-type workloads.Comment: 17 page

Functional Conservation Of The Male Germ-line Regulator DUO1 In Flowering Plants

In flowering plants the development of the male germ-line in pollen to form two functional sperm cells is essential for reproduction. DUO1 an R2R3 MYB transcription factor plays a key role in regulating genes required for germ-line division and specification into mature sperm cells. Mutant duo1 pollen contain a singular germ-like cell that cannot fertilize. Present studies of DUO1 have focused on the model organism Arabidopsis thaliana with regulation of DUO1 being of interest. This study tests if regulatory mechanisms are evolutionarily conserved across diverse flowering plant species with a focus on the legume Medicago truncatula. A DUO1 orthologue in M. truncatula was able to complement the A. thaliana duo1 mutant through restoring mitotic function at pollen mitosis II. Specification and differentiation of the male germ-line was also restored as shown by successful male transmission from the complemented male germ-line. This indicated functional conservation between the two proteins. In the A. thaliana DUO1 promoter a cis-regulatory module, Regulatory region of DUO1 (ROD1) is known to provide germ-line specific expression. Here analysis of the full length M. truncatula DUO1 promoter using a fluorescent promoter reporter showed male germ-line specific GFP fluorescence in A. thaliana during pollen development similar to that of the A. thaliana DUO1 promoter. Analysis of a 5ˊ deletion series of the M. truncatula DUO1 promoter then identified key regions necessary for expression with no GFP seen in a construct lacking the ROD1 module. The ROD1 regulatory module from M. truncatula was then isolated and used in a promoter reporter to show that M. truncatula ROD1 provides germ-line specific expression similar to A. thaliana ROD1. Collectively these results demonstrated that ROD1 is an evolutionarily conserved cis-regulatory module that determines germ-line specific expression of DUO1 critical for pollen development in dicotyledonous plants. A. thaliana and M. truncatula DUO1 is thought to be able to auto-activate expression through DUO1 binding sites in the DUO1 promoter. This was explored through dual luciferase assays, however technical difficulties lead to inconclusive results and no clear conclusions could be made

Incremental Semantics for Dialogue Processing: Requirements, and a Comparison of Two Approaches

International audienceTruly interactive dialogue systems need to construct meaning on at least a word-byword basis. We propose desiderata for incremental semantics for dialogue models and systems, a task not heretofore attempted thoroughly. After laying out the desirable properties we illustrate how they are met by current approaches, comparing two incremental semantic processing frameworks: Dynamic Syntax enriched with Type Theory with Records (DS-TTR) and Robust Minimal Recursion Semantics with incremental processing (RMRS-IP). We conclude these approaches are not significantly different with regards to their semantic representation construction, however their purported role within semantic models and dialogue models is where they diverge

Marshall University Music Department Presents the MU Guitar Ensemble

https://mds.marshall.edu/music_perf/1280/thumbnail.jp

Localized vs distributed deformation associated with the linkage history of an active normal fault, Whakatane Graben, New Zealand

The deformation associated with an active normal fault is investigated at a high temporal resolution (c. 104 yr). The Rangitaiki Fault (Whakatane Graben, New Zealand) and its adjacent faults accommodated an overall extension of ?0.83% oriented at ?N324°E over the past 17 kyr. This is consistent along strike, but the pattern of faulting that accommodates this strain defines two different spatial domains. To the SW, one domain is characterized by a few large faults, with >80% of strain localized onto geometrically and kinematically linked segments of the main fault. This produces marked heterogeneity in the spatial distribution of strain across the graben. In contrast, to the NE, a domain of distributed faulting is characterized by numerous small faults contributing to the overall deformation, with only ?35% of strain localized onto the Rangitaiki Fault. The transition from distributed to localized deformation is attributed to an increase in linkage maturity of the Rangitaiki Fault. Progressive strain localization has been ongoing within the network over the last 17 kyr, with localization of fault activity increasing by ?12%, indicating this process occurs over kyr time periods that only reflect a few earthquake events