Relating vanishing points to catadioptric camera calibration

This paper presents the analysis and derivation of the geometric relation between vanishing points and camera parameters of central catadioptric camera systems. These vanishing points correspond to the three mutually orthogonal directions of 3D real world coordinate system (i.e. X, Y and Z axes). Compared to vanishing points (VPs) in the perspective projection, the advantages of VPs under central catadioptric projection are that there are normally two vanishing points for each set of parallel lines, since lines are projected to conics in the catadioptric image plane. Also, their vanishing points are usually located inside the image frame. We show that knowledge of the VPs corresponding to XYZ axes from a single image can lead to simple derivation of both intrinsic and extrinsic parameters of the central catadioptric system. This derived novel theory is demonstrated and tested on both synthetic and real data with respect to noise sensitivity

Development of Approaches of Tumor Trapping Enhanced BB2R-Targeted Radiopharmaceuticals for Prostate Cancer

The Gastrin-Releasing Peptide Receptor (BB2r) has been intensively investigated as a cancer target over the years. Numerous diagnostic and therapeutic BB2r-targeted agents have been developed for various solid tumors, including prostate cancers, due to the high expression level of BB2r on neoplastic relative to normal tissues. The development of those targeted agents have mainly utilized the modified c-terminal of bombesin(BBN), a peptide that has nanomolar binding affinity to human BB2r. However, a major issue that hinders the clinical translational potential of low-molecular weight, receptor-targted agents, is their short residence time at tumor tissues due to the intrinsically high diffusion and clearance rates. Detailed in this dissertation is a comparison study investigating important biological differences between two mouse models of prostate cancer and how these factors impact the delivery of BB2r-targeted agents. Specifically, we have evaluated the impact of differences in tumor vassculatur density, hypoxia burden and perfusion efficacy on BB2r-targeted agent uptake and distribution. Furthermore, herein, we proposed two different approaches to increase the tumor residualization of BB2r-targeted radiopharmaceutical agents, by developing chemical approaches to “trap” BB2r-targeted agents in prostate cancer cells through adduct formation with macromolecules. First proposed, BB2r-targted agents incorporating hydrophilic cysteine cathepsin (CC) inhibitors was developed. Due to the high concentration of CCs found in endolysosomal compartments, our agents have the ability to irreversibly bind to CCs after endocytosis. Two analogs, based on BB2r-targeted agonist and antagonist separately, demonstrated enhanced tumor retention and optimal tumor-to-non-target ratios compared to the matching controls. The second approach focused on the hypoxic nature of prostate cancer, which is due to the distorted architecture leading to the insuffucient delivery of oxygen, and was examined as a mechanism to increase retention of BB2r-targeted agents. Specifically, we explored the hypoxic-selectivity of a 2-nitroimidazole phosphoramide nitrogen mustard (2-NIPAM), a potential tumor trapping agent which is able to irreversibly bind to intracellular nucleophiles in hypoxic tissues. Overall, we seek to determine the most suitable mouse model in evaluating the BB2r-targeted agents. We are also exploring strategies to elongate the retention time of BB2r-targeted agents in the prostate tumor tissues, thereby increasing the clinical translational potential of these agents. Future works include: 1) synthesis and evaluation of 2-NIPAM incorporated BB2r-targeted peptides in vitro and in vivo; 2) synthesis and assessment of hydrophilic CC inhibitors integrated into other receptor-targeted analogs. Further work is needed to demonstrate the feasibility and wide applicability of our strategies in different receptor-targeted systems

Exchange Rate Dynamics, Intervention and Regime Shifts in China: A Market Microstructure Analysis

This thesis applies the market microstructure approach to investigate exchange rate dynamics, intervention and regime shifts in China’s exchange rate system. This research first examines exchange rate determination and dynamics from a microstructural perspective. An index of order flow is constructed in the Chinese context to reflect excess demand pressure. A VAR model is then estimated to explore to what extent order flow may explain long-term determination and short-term fluctuations of the renminbi exchange rate. Focusing on the cointegrating relationship between cumulative order flow and the exchange rate of the RMB against the US dollar, this research find that in the new Chinese exchange rate regime in place since 2005, order flow is able to explain a significant part of fluctuations in the RMB-dollar exchange rate. China is internationally noted for its intervention in the foreign exchange market. Based on high-frequency data this thesis adopt a multi-dimensional approach to explore how interventions are conducted in China, what the consequences are, and to what extent they are effective. This thesis identify evidence of China’s extensive intervention and find that the authority is more likely to intervene to curb devaluation. Decomposition analysis shows that the direct impact of intervention on the exchange rate is more important than the impact via order flow. Intervention via the central bank’s involvement in trading is effective in influencing both the exchange rate and order flow, but tends to increase volatility. Intervention by the central bank’s varying the central parity condition plays some role in ‘leaning against the wind’, but cannot reverse the trend. China announced the reform of its exchange rate system in 2005. The reform was disrupted by the breakout of the global financial crisis around 2008, but was reiterated in 2010. The thesis analyses the behaviour of China’s exchange rate policy since then. This research detect 21st June 2010 as the date of regime shift, since when the RMB has been allowed greater room for flexibility, and consequently exchange rate volatility has increased. This research unearths evidence confirming that the renminbi no longer pegs only to the dollar. During the crisis period, deviations from the central parity rate (CPR) increase the possibility of government intervention, and the intervention correlates with bid-ask exchange rate spread. The Chinese monetary authority is found to act to keep the exchange rate stable. In the post-crisis period, the correlation becomes time-varying and the government prefers the RMB exchange rate to gradually appreciate. This research finds evidence that appreciation of the RMB exchange rate is order flow driven during the post-crisis period. There is a significant negative currency exposure during the financial crisis, caused by changes in the RMB exchange rate, indicating that the Chinese stock market exhibits a negative reaction in the period. However, no significant impact is found in the post- crisis period. In order to modify the exchange rate exposure to fluctuations of the US dollar, the Chinese government seems to have adopted the relatively more efficient exchange rate regime to handle the effects of the global financial crisis

Examining Factors Impacting Purchase Intention of 3D Cameras of Gen Y Customers In Chengdu, China

Purpose: In marketing studies, purchase intention is a key indicator for the product development, marketization and sales strategy. Therefore, this study aims to examining factors impacting purchase intention of 3D cameras of Generation Y customers in Chengdu, China. Research design, data and methodology: This quantitative research selects 500 consumers between the age of 25 and 40 years old who are living in Chengdu, China and have at least one year of experience with top three 3D camera brands. Sampling techniques are judgmental, quota and convenience samplings. Item Objective Congruence (IOC) Index validity test and Cronbach’s Alpha reliability test were approved before the data collection. SPSS and SPSS Amos statistical software were implemented for Confirmatory Factor Analysis (CFA), including factor loadings, convergent validity, discriminant validity, composite reliability, AVE and goodness of fit. Structural Equation Model (SEM) was applied to test hypotheses. Results: Gen Y customers' purchase intention is significantly impacted by social influence, perceived quality, attitude, satisfaction, and trust. In addition, trust has the strongest significant influence on customer’s purchase intention of 3D Cameras. Conclusions: The findings contribute to marketers and salespersons to understand motivational factors of 3D cameras’ purchase decision of Generation Y customers, leading to the development of marketing and sales strategy for such products

The Influencing Factors of Gen Y Consumers' Purchase Intention of 3D Cameras in Mianyang, China

Purpose: The purpose of this study is to examine relationship between social influence, perceived quality, attitude, satisfaction, and trust that influence purchase intention of 3D cameras of Generation Y customers in Mianyang, China. Research design, data and methodology: The quantitative method was used to distributing online questionnaire to 500 participants between the age of 25 and 40 years old, who are living in Mianyang, China and have at least one year of experience with top three 3D camera brands. Judgmental, quota and convenience sampling techniques were carried out. Before collecting the data, validity and reliability results were accepted by using Item Objective Congruence (IOC) Index and Cronbach’s Alpha reliability test. Confirmatory Factor Analysis (CFA) was applied to measure factor loadings, convergent validity, discriminant validity, composite reliability, AVE and goodness of fit. The effect between relationships and hypotheses were accounted by Structural Equation Model (SEM). Results: The findings reveal that trust has the strongest significant influence on customer’s purchase intention of 3D Cameras. Additionally, social influence, perceived quality, attitude, satisfaction, and trust have a significant impact on Gen Y customers' purchase intention. Conclusions: The recommendations were made for manufacturers, dealers, marketers and salespersons to develop marketing and sales strategies for raising customer’s purchase intention

Fence-sitters Protect Cooperation in Complex Networks

Evolutionary game theory is one of the key paradigms behind many scientific disciplines from science to engineering. In complex networks, because of the difficulty of formulating the replicator dynamics, most of previous studies are confined to a numerical level. In this paper, we introduce a vectorial formulation to derive three classes of individuals' payoff analytically. The three classes are pure cooperators, pure defectors, and fence-sitters. Here, fence-sitters are the individuals who change their strategies at least once in the strategy evolutionary process. As a general approach, our vectorial formalization can be applied to all the two-strategies games. To clarify the function of the fence-sitters, we define a parameter, payoff memory, as the number of rounds that the individuals' payoffs are aggregated. We observe that the payoff memory can control the fence-sitters' effects and the level of cooperation efficiently. Our results indicate that the fence-sitters' role is nontrivial in the complex topologies, which protects cooperation in an indirect way. Our results may provide a better understanding of the composition of cooperators in a circumstance where the temptation to defect is larger.Comment: an article with 6 pages, 3 figure

Emergence of Cooperation in Non-scale-free Networks

Evolutionary game theory is one of the key paradigms behind many scientific disciplines from science to engineering. Previous studies proposed a strategy updating mechanism, which successfully demonstrated that the scale-free network can provide a framework for the emergence of cooperation. Instead, individuals in random graphs and small-world networks do not favor cooperation under this updating rule. However, a recent empirical result shows the heterogeneous networks do not promote cooperation when humans play a Prisoner's Dilemma. In this paper, we propose a strategy updating rule with payoff memory. We observe that the random graphs and small-world networks can provide even better frameworks for cooperation than the scale-free networks in this scenario. Our observations suggest that the degree heterogeneity may be neither a sufficient condition nor a necessary condition for the widespread cooperation in complex networks. Also, the topological structures are not sufficed to determine the level of cooperation in complex networks.Comment: 6 pages, 5 figure

Papel de los microARNs en el diagnóstico del carcinoma hepatocelular relacionado con el virus de la hepatitis B y su papel en la regulación del ADN circular covalente cerrado en pacientes con hepatitis B crónica en la zona gris

Antecedentes: La infección por el virus de la hepatitis B (VHB) sigue siendo un problema de salud pública mundial, destacando como el principal factor de riesgo del carcinoma hepatocelular (CHC). La mayoría de los pacientes con hepatitis B crónica (HBC) se encuentran en alguna de las 5 fases de la historia natural del VHB definidas por la Asociación Europea para el Estudio del Hígado (EASL) en 2017, pero algunos individuos no encajan en ninguno de los estados inmunes habituales y se consideran estar en la “zona gris (ZG)”. El ADN circular covalente cerrado (ADNccc) juega un papel clave en el ciclo de vida del virus y no puede ser eliminado por las terapias actuales. Además, la cuantificación del ADNccc no es fácil de generalizar debido a la naturaleza invasiva de la biopsia hepática. La creciente evidencia indica que los microARNs (miARNs) podrían regular la expresión del ADNccc intrahepático, participar en el diagnóstico y la historia natural de la enfermedad. Objetivos: (1) Realizar un metaanálisis para evaluar la precisión diagnóstica de miARN circulante como biomarcador no invasivo en el diagnóstico precoz del CHC relacionado con el VHB (CHC-VHB). (2) Explorar los marcadores subrogados no invasivos para ADNccc intrahepático en pacientes con hepatitis B crónica en la zona gris (HBC-ZG). (3) Explorar el papel regulador de los miARNs en la expresión del ADNccc en pacientes con HBC-ZG, establecer una red de interacción miARN-ARNm y proporcionar una base teórica para encontrar nuevas dianas terapéuticas. Materiales y métodos: Después de una revisión sistemática de los estudios relevantes, se combinaron la sensibilidad, la especificidad, la razón de verosimilitud positiva (PLR) y negativa (NLR), la odds ratio de diagnóstico (DOR) y el área bajo la curva (AUC) para diagnosticar el CHC-VHB. Se realizó un análisis de metarregresión y un análisis de subgrupos para explorar la heterogeneidad y se utilizó el gráfico en embudo de Deeks para evaluar el sesgo de publicación. Se incluyeron un total de 13 pacientes con HBC-ZG. Se cuantificaron el ADNccc intrahepático y los marcadores séricos de actividad virológica (incluido el ARNpg-VHB, ADN-VHB, cuantificación del HBsAg, ALT y AST). Las correlaciones entre el ADNccc intrahepático y los marcadores séricos de actividad virológica se analizaron mediante la prueba de correlación de Spearman. Se consideró estadísticamente significativa cuando p < 0,05. Según el nivel de expresión de ADNccc intrahepático, 13 pacientes con HBC-ZG se dividieron en grupo de referencia (n = 7) con ADNccc log1,5 y el valor p < 0,05 se establecieron como valor de corte. A continuación, se realizaron los análisis de enriquecimiento de las vías GO, KEGG y GSEA. Además, las interacciones miARN-ARNm se adquirieron a partir de miRTarBase, y se empleó cytoscape para construir la red de miARN-ARNm. Se calcularon el coeficiente de correlación de Pearson (r) y su valor p. Se consideró que la correlación entre miARN-ARNm diana era fuerte cuando el coeficiente era r < - 0,7 y el valor p < 0,01. Resultados: En el metaanálisis actual se incluyeron 19 artículos que incluyen 32 estudios. La sensibilidad, especificidad, PLR, NLR, DOR y AUC generales fueron 0,83 (IC 95%: 0,79 - 0,87), 0,78 (IC 95%: 0,73- 0,83), 3,9 (IC 95%: 3,0 - 4,9), 0,21 (IC 95%: 0,16 - 0,27), 18 (IC 95%: 12 - 27) y 0,88 (IC 95%: 0,85 - 0,91), respectivamente. El análisis de subgrupos muestra que el uso de los clusters de miARN junto con un aumento del tamaño de muestra pueden mejorar la precisión diagnóstica. Además, no hay sesgo de publicación. En pacientes con HBC-ZG, se vieron correlaciones significativas entre los niveles séricos de ARNpg-VHB, ADN-VHB y cuantificación del HBsAg con ADNccc intrahepático (r = 0,790, p = 0,001, r = 0,660, p = 0,013, y r = 0,730, p = 0,004, respectivamente). Se cribaron un total de 19 ED miARNs que consisten en 7 ED miARNs up-regulados y 12 down-regulados, y 340 ED ARNm que consisten en 180 up-regulados y 160 down-regulados. Los términos GO más enriquecidos estaban relacionados con el proceso biológico del virus, como la regulación del ciclo de vida viral, la regulación del proceso viral y la regulación de la replicación del genoma viral. El análisis de enriquecimiento de la vía KEGG sugirió que estos objetivos predichos estaban vinculados con la hepatitis B. Finalmente, se estableció una posible red reguladora de miARN-ARNm basada en los resultados del análisis de correlación de expresión, entre los cuales miR-4295 - ZNF224 mostró una correlación relativamente alta. Conclusión: Los miARNs circulantes (especialmente el miR-125b) podrían servir como un biomarcador no invasivo potencial en el diagnóstico precoz de pacientes con CHC-VHB. Existe una correlación significativa entre el ARNpg-VHB sérico y el ADNccc intrahepático en pacientes con HBC-ZG, lo que indica que el ARNpg-VHB sérico es un potencial biomarcador subrogado fiable del ADNccc intrahepático. La disminución de la expresión de miR-4295 en pacientes con HBC-ZG con bajo nivel de ADNccc está relacionada con el aumento de la expresión de ZNF224, que está involucrado en el proceso biológico de la replicación del virus y la regulación del ciclo de vida. Nuestros hallazgos pueden proporcionar nuevos objetivos potenciales para el tratamiento de HBC. En el futuro, se necesitan más experimentos para verificar nuestros hallazgos

In Vivo Molecular Imaging in Retinal Disease

There is an urgent need for early diagnosis in medicine, whereupon effective treatments could prevent irreversible tissue damage. The special structure of the eye provides a unique opportunity for noninvasive light-based imaging of ocular fundus vasculature. To detect endothelial injury at the early and reversible stage of adhesion molecule upregulation, some novel imaging agents that target retinal endothelial molecules were generated. In vivo molecular imaging has a great potential to impact medicine by detecting diseases or screening disease in early stages, identifying extent of disease, selecting disease and patient-specific therapeutic treatment, applying a directed or targeted therapy, and measuring molecular-specific effects of treatment. Current preclinical findings and advances in instrumentation such as endoscopes and microcatheters suggest that these molecular imaging modalities have numerous clinical applications and will be translated into clinical use in the near future