Progression of Alzheimer's disease has been associated with the deposition of aggregated amyloid beta (Aβ) protein in the brain. Though first described in post-mortal tissue, the development of Aβ specific tracers for positron emission tomography (PET) permits in-vivo mapping of its distribution in the brain. One of the well-known and early-developed tracers is the Pittsburgh Compound B (PiB) (Klunk et al., 2004). However, the challenge with PiB lies in the stability of the radioisotope 11C. 11C's short half-life of only 20 minutes hinders its transportation and usage at imaging facilities that are not in close proximity with the radioisotopes manufacturer. Recently, an alternative Aβ tracer has been developed, Florbetapir (Wong et al, 2010.), with a half-life of 110 minutes that should allow wider accessibility to imaging sites while improve the detection of Aβ. To define better the specificity and utility of Florbetapir, we propose to utilize existing PET data acquired with the radioactive tracer Florbetapir from the Alzheimer's disease Neuroimaging Initiative (ADNI). Our goal is to characterize the symmetry of Aβ protein deposition in the brain of patients with Alzheimer's disease. While a previous study has investigated this issue using PiB, Florbetapir has not been used. Our project will involve data post-processing by segmenting out non-brain tissues. Segmented data is then normalized by the pixel intensity and a distribution curve is created using MathCad program. In addition, we will calculate the asymmetry score for Regions of Interest. This will permit comparison of the uptakes of tracer between brain hemispheres to be made. Results from our project can provide insight into Florbetapir's binding affinity for Aβ. In addition, Florbetapir's potential as a better alternative to PiB can also be evaluated.

BACKGROUND: Pre-term delivery is known to cause developmental problems due to the fragile nature of the premature brain. In particular, ventriculomegaly is a commonly observed phenomenon due to the hemorrhaging of the germinal matrix, and may cause alterations in the volumes of gray matter, white matter and cerebrospinal fluid in growing pre-term children. METHODS: The volume and symmetry of a sample population of ELGAN (Extremely Low Gestational Age Newborns) and normal-term population obtained from the NIH Study of Normal Brain Development was evaluated. The ELGAN group consisted of 88 subjects from age group 9 to 11 and the normal-term group consisted of 68 subjects from age group 7 to 11. Magnetic resonance images were taken from both samples and the intracranial matter was measured and segmented. RESULTS: Histograms of the obtained volumes showed a normal distribution and statistical analysis for each sample group and gender. The ELGAN group had higher intracranial volumes and showed statistically significant asymmetry that was not present in the normal term population with a larger right brain than left brain. Discussion: Results indicate that preterm delivery may alter processes that allow for symmetrical brain development and heavily favor the relative higher expansion of the right side of the brain. CONCLUSION: Further analysis of the concentration and location of the white matter and gray matter in both preterm and normal term children is necessary in order to understand the adaptive mechanisms that may be activated in order to offset the damage done to the premature brain.

Li Changzheng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 43-44). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Preliminaries --- p.3 / Chapter 2.1 --- Clifford Algebras --- p.3 / Chapter 2.2 --- Spin Representation and Spinor Bundles --- p.7 / Chapter 2.3 --- Normed Division Algebras --- p.11 / Chapter 3 --- Associated Representations on /\. V* --- p.15 / Chapter 3.1 --- Exterior Forms and Spinors --- p.15 / Chapter 3.2 --- Direct Calculations --- p.16 / Chapter 3.3 --- "u(l,l,K) Action on V + V*" --- p.24 / Chapter 3.4 --- "su(l,l,K)´so(R1´ة0+K)" --- p.30 / Chapter 4 --- Some Applications to Geometry --- p.35 / Chapter 4.1 --- Holonomy Representations and Spinor Bundles --- p.35 / Chapter 4.2 --- The Lefschetz Action: Kahler Case --- p.37 / Chapter 4.3 --- The Lefschetz Action: HyperKahler Case --- p.41 / Bibliography --- p.43

Many real life problems can naturally be modeled as constraint satisfaction problems (CSPs), which can sometimes contain both variable symmetries and value symmetries. Tree search based CSP solving algorithms often suffer from symmetries, which creates symmetrically equivalent states in the search tree. Exploring more than one of the symmetrically equivalent states is a waste of search efforts. Adding symmetry breaking constraints to a CSP can force the search to visit only one of the symmetrical regions and helps reduce search space. While variable symmetry breaking constraints can be expressed relatively easily and executed efficiently by enforcing lexicographic ordering, value symmetry breaking constraints are often difficult to formulate. In this thesis, we propose two methods of using symmetry breaking constraints to tackle value symmetries. In the first method, we show theoretically when value symmetries in one CSP model correspond to variable symmetries in another CSP model of the same problem. We also show when variable symmetry breaking constraints in the two models, combined using channeling constraints, are consistent. Such results allow tackling value symmetries efficiently using additional CSP variables and channeling constraints. In the second method, we identify a common and important class of value symmetries, namely symmetries of indistinguishable values, and introduce value precedence to break such symmetries. Although value precedence can be expressed straightforwardly using if-then constraints in existing constraint programming systems, the resulting formulation is inefficient both in terms of size and runtime. We present two propagation algorithms for implementing global constraints on value precedence for integer and set variables respectively. We also characterize the propagation levels attained by various usages of the global constraints and the conditions when the constraints are consistent with variable symmetry breaking constraints. Extensive experiments are conducted to verify the feasibility and efficiency of our two proposals. / Law Yat Chiu. / "September 2005." / Adviser: Jimmy Ho Man Lee. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3905. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 112-123). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

This thesis presents the search for the supersymmetric partner of the top quark in p s Æ 13 TeV proton-proton collisions at the LHC using data collected by the ATLAS detector in 2015 and 2016. Results were interpreted considering natural supersymmetric extensions of the Standard Model in R-parity conserving decays. Events characterised by four or more jets and missing transverse momentum in the final states were selected. The performance of the tracking algorithms used by the ATLAS online trigger were studied. Optimisation studies of the search regions to increase the sensitivity to supersymmetric signals were performed and data-driven techniques to estimate StandardModel backgrounds were employed. The agreement between data and background predictionswas extensively checked and the extrapolations frombackgroundenriched regions to signal-enriched regions were validated. The analysis yielded no significant excess therefore exclusion limits on various models were set.

Poggio and Vetter (1992) showed that learning one view of a bilaterally symmetric object could be sufficient for its recognition, if this view allows the computation of a symmetric, "virtual," view. Faces are roughly bilaterally symmetric objects. Learning a side-view--which always has a symmetric view--should allow for better generalization performances than learning the frontal view. Two psychophysical experiments tested these predictions. Stimuli were views of shaded 3D models of laser-scanned faces. The first experiment tested whether a particular view of a face was canonical. The second experiment tested which single views of a face give rise to best generalization performances. The results were compatible with the symmetry hypothesis: Learning a side view allowed better generalization performances than learning the frontal view.

Many observables have been developed to study the effects of the two component nature of nuclei. This dissertation has experimentally probed caloric curves as well as scaling observables for their dependence on the asymmetric portion of the nuclear equation of state. Projectile fragmentation sources were identified from the reactions of 86,78Kr+64,58Ni at 35 MeV/A taken on the NIMROD-ISiS array. The angular coverage, excellent isotopic resolution, and Neutron Ball allow for quasi-complete event reconstruction in both charge and mass. A new thermometer for nuclear fragmentation studies has been derived and is presented here. In this thermometer, the temperature is obtained from fluctuations of the transverse momentum. The proton transverse momentum fluctuations are used in this thesis to study the N/Z dependence of the nuclear caloric curve. The caloric curve constructed from proton momentum fluctuations does not show a significant dependence on the source N/Z ratio. Two other thermometers have also been studied in this thesis: the double isotope ratio, and moving source slope thermometers. These thermometers show no statistically significant dependence on the source N/Z. The source density has been derived from the evolution of fragment Coulomb barriers with increasing E*/A. This density showed no source N/Z dependence. However, a strong evolution in source density over the E*/A=1.5-7.5 MeV region was observed. Fragment scaling was investigated through isoscaling and power law scaling. The power law scaling showed a strong dependence on the source N/Z. This source N/Z dependence was further investigated through isoscaling. The fragment yields of this data have been shown to exhibit consistent isoscaling for Z=1-17. In addition, isoscaling was observed in data cut on the E*/A of the source yielding decreasing slopes (a) as a function of E*/A. This decrease, normalized to the asymmetries of the sources (a/delta), has been linked to a decrease in the asymmetry coefficient Csym. This dissertation has shown that the experimentally observed decrease in Csym with E*/A is well correlated to the temperature and density changes experimentally observed in this data.

No description available.

People prefer symmetric over asymmetric patterns (Reber, Schwarz, & Winkielman, 2004). According to the fluency attribution perspective, this preference reflects differences in processing speed where increased processing efficiency leads to increased pattern preference. To test the account, in Experiment 1, participants’ speed of response to a pattern predicted the relationship between pattern symmetry and pattern preference. Experiment 2 expanded this account and found that a second measure of processing efficiency, recognition accuracy for patterns, predicted the relationship between pattern symmetry and pattern preference. Experiment 3 tested the attribution account of the fluency attribution hypothesis. Participants made a judgment of pattern mood rather than pattern preference. Despite a change of judgment task to an unintuitive judgment of pattern mood, participants attributed increased processing efficiency for patterns to increased pattern happiness. The three experiments provide an integration of the information processing and fluency attribution perspectives to account for symmetry preference judgments.

No description available.