Optical Coherence Photoacoustic Microscopy (OC-PAM) for Multimodal Imaging

Optical coherence tomography (OCT) and Photoacoustic microscopy (PAM) are two noninvasive, high-resolution, three-dimensional, biomedical imaging modalities based on different contrast mechanisms. OCT detects the light backscattered from a biological sample either in the time or spectral domain using an interferometer to form an image. PAM is sensitive to optical absorption by detecting the light-induced acoustic waves to form an image. Due to their complementary contrast mechanisms, OCT and PAM are suitable for being combined to achieve multimodal imaging. In this dissertation, an optical coherence photoacoustic microscopy (OC-PAM) system was developed for in vivo multimodal retinal imaging with a pulsed broadband NIR light source. To test the capabilities of the system on multimodal ophthalmic imaging, the retina of pigmented rats was imaged. The OCT images showed the retinal structures with quality similar to conventional OCT, while the PAM images revealed the distribution of melanin in the retina since the NIR PAM signals are generated mainly from melanin in the posterior segment of the eye. By using the pulsed broadband light source, the OCT image quality highly depends on the pulse-to-pulse stability of the light source without averaging. In addition, laser safety is always a concern for in vivo applications, especially for eye imaging with a pulsed light source. Therefore, a continuous wave (CW) light source is desired for OC-PAM applications. An OC-PAM system using an intensity-modulated CW superluminescent diode was then developed. The system was tested for multimodal imaging the vasculature of a mouse ear in vivo by using Gold Nanorods (GNRs) as contrast agent for PAM, as well as excised porcine eyes ex vivo. Since the quantitative information of the optical properties extracted from the proposed NIR OC-PAM system is potentially able to provide a unique technique to evaluate the existence of melanin and lipofuscin specifically, a phantom study has been conducted and the relationship between image intensity of OCT and PAM was interpreted to represent the relationship between the optical scattering property and optical absorption property. It will be strong evidence for practical application of the proposed NIR OC-PAM system

Liquid Chromatography - Mass Spectrometry for the Study of Arachidonic Acid Metabolites

LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY FOR THE STUDY OF ARACHIDONIC ACID METABOLITES Xiaojing Liu Ian A. Blair, PhD Arachidonic acid (AA) oxidation metabolism has been an important research topic for decades, and numerous oxidation products as well as enzymes involved in AA metabolism together with their downstream metabolites have been identified, although unknown pathways still remain to be characterized. In the present a study a new AA metabolite, 11-oxo-eicosatetraenoic acid (ETE), generated from a major product of cyclooxygenase (COX-2), 11(R)-hydroxyeicosatetraenoic acid (HETE), through 15-hydroxyprostaglandine dehydrogenase (15-PGDH)-mediated oxidation. 11-Oxo-ETE was found to have an anti-proliferative effect on human umbilical vein endothelial cells (HUVECs), with a similar IC50 to a well- known anti-inflammatory mediator, 15-deoxy-12,14-prostaglandin J2 (15d-PGJ2). It was also found that 11-oxo-ETE could be inactivated through the glutathione-S-transferase (GST)/glutathione (GSH) pathway by forming a GSH adduct, or by undergoing reduction to 11(S)-HETE through metabolism by unknown reductases. AA is also subject to non-enzymatic oxidation due to its bis-allylic hydrogen atoms and four double bonds. Chiral LC-MS methods were used to distinguish the enzymatic and non-enzymatic products by monitoring the relevant products that were formed. Non-enzymatic pathways generate racemic mixtures, while enzymatic pathways are normally highly stereoselective. It is known that both enzymatic and non-enzymatic oxidation of AA followed by decomposition of the resulting oxidized intermediates, can generates short-chain aldehydes such as 4-hydroperoxy-2(E)-nonenal (HPNE), 4-hydroxy-2(E) nonenal (HNE), and 4-oxo-2(E)-nonenal (ONE). However, it was discovered that the endoperoxide product of COX-2, PGG2, is a major contributor to the formation of these aldehydes. Moreover, PGG2 and other hydroperoxides generate HPNE or HNE with different chiral characteristics. From COX-2 expressing human colorectal adenocarcinoma epithelial cell line (LoVo) cell lysate, 4(S)-HNE was detected with high enantiomeric purity indicating that the primary source was prostaglandin G2 (PGG2) and not 15- hydroperoxyeicosatetraenoic acid (HPETE) as had been previously suggested. Finally, through studies of 11(R)-HPETE and 15-HPETE decomposition, a new carboxylate-containing aldehyde, 11-oxoundeca-5,8-dienoic acid (OUDE) was identified. OUDE contains the -terminus of the lipid hydroperoxide precursor and is analogous to HNE, which is derived from the -terminus. Nuclear magnetic resonance spectroscopy (NMR) together with chiral liquid chromatography-mass spectrometry (LC-MS) analysis showed that OUDE was a mixture of two double bond isomers. It has been proposed that the two isomers are generated as a result of a rearrangement reaction subsequent to the formation of OUDE. In addition, , by monitoring the chirality of the HNE that was formed from 11(R)-HPETE and 15-HPETE decomposition, a homolytic mechanism for HNE formation has been proposed

Adaptive Non-myopic Quantizer Design for Target Tracking in Wireless Sensor Networks

In this paper, we investigate the problem of nonmyopic (multi-step ahead) quantizer design for target tracking using a wireless sensor network. Adopting the alternative conditional posterior Cramer-Rao lower bound (A-CPCRLB) as the optimization metric, we theoretically show that this problem can be temporally decomposed over a certain time window. Based on sequential Monte-Carlo methods for tracking, i.e., particle filters, we design the local quantizer adaptively by solving a particlebased non-linear optimization problem which is well suited for the use of interior-point algorithm and easily embedded in the filtering process. Simulation results are provided to illustrate the effectiveness of our proposed approach.Comment: Submitted to 2013 Asilomar Conference on Signals, Systems, and Computer

Global-Scale Resource Survey and Performance Monitoring of Public OGC Web Map Services

One of the most widely-implemented service standards provided by the Open Geospatial Consortium (OGC) to the user community is the Web Map Service (WMS). WMS is widely employed globally, but there is limited knowledge of the global distribution, adoption status or the service quality of these online WMS resources. To fill this void, we investigated global WMSs resources and performed distributed performance monitoring of these services. This paper explicates a distributed monitoring framework that was used to monitor 46,296 WMSs continuously for over one year and a crawling method to discover these WMSs. We analyzed server locations, provider types, themes, the spatiotemporal coverage of map layers and the service versions for 41,703 valid WMSs. Furthermore, we appraised the stability and performance of basic operations for 1210 selected WMSs (i.e., GetCapabilities and GetMap). We discuss the major reasons for request errors and performance issues, as well as the relationship between service response times and the spatiotemporal distribution of client monitoring sites. This paper will help service providers, end users and developers of standards to grasp the status of global WMS resources, as well as to understand the adoption status of OGC standards. The conclusions drawn in this paper can benefit geospatial resource discovery, service performance evaluation and guide service performance improvements.Comment: 24 pages; 15 figure

Exploring the Path of Ideological and Political Construction in Courses under the “One Body, Two Wings” Model - Taking the Course of Engineering Law Principles and Practice as an Example

The comprehensive advancement of ideological and political construction in university courses is a significant strategic move to thoroughly implement the important educational directives of General Secretary Xi Jinping and to fulfill the fundamental task of moral education. Universities should deepen educational and teaching reforms, thoroughly explore the ideological and political resources of courses, fully leverage the educational role of each course, and comprehensively improve the quality of talent training. The course on Engineering Law Principles and Practice has explored and practiced the path of ideological and political construction in courses. With the “One Body, Two Wings” model as the construction approach, it explores the path of ideological and political construction in this course. Focusing on student development, the course unfolds teaching through innovative application in teaching and value shaping for students as two wings. In terms of value shaping, it emphasizes not only exploring the ideological and political elements of the course in line with the actual situation of students but also requires teachers to lead by example and set a model for moral education. Additionally, establishing a scientific and effective evaluation system for the teaching effects of course ideological and political education ensures the effectiveness of the entire course’s ideological and political education. The teaching of the entire course enables students to not only learn knowledge and skills but also cultivate integrity, achieving the educational goals of the course