Active Galactic Nuclei throughout the Spectrum: M 87, PKS 2052-47, and the MOJAVE sample

Active galactic nuclei (AGN) are one of the many mysteries in the Universe. AGN hosts a super massive black hole (SMBH) in its center surrounded by a rotating accretion disk, and a powerful jet is ejected along the pole directions of the accretion disk. The powerful jet is definitely the highlight of AGN. Those extragalactic jets appears to have superluminal motions up to 60 c, and they are very luminous and variable across the electromagnetic spectrum. The jets can be highly polarized, which indicates the existence of strong magnetic fields; they can have a highly bended morphology due to reasons we do not completely understand. Astronomers have been studying AGN jets for the past decades by performing observations from the radio to the gamma-ray band, applying physical jet models to the observed properties, and trying to put the pieces into the whole picture. We now understand many aspects of the AGN phenomena, but a significant part is still missing. The aim of this thesis is to study the extragalactic jets by using different approaches. We investigate: (i) a bright feature in the jet of the radio galaxy M 87 as observed using high-resolution VLBI technique; (ii) a multiband flare of the blazar PKS 2052-47 by conducting a multifrequency campaign; (iii) the broadband spectral energy distribution (SED) of a radio-selected, statistically-complete sample of the most conspicuous AGN in the Northern sky: the Monitoring Of Jets in Active galactic nuclei with VLBA Experiments (MOJAVE) sample. Very long baseline interferometry (VLBI) is a powerful technique that can resolve distant AGN to parsec-scales by combining global radio antennas to perform together as a giant telescope with a radius of the earth. With the VLBI technique, we are able to trace bright features being ejected from the center moving along the jet. In this thesis, we use the VLBI technique to detect a bright knot 80 pc from the center of the radio galaxy M 87. It was suggested that the HST-1 knot was the site where a TeV flare of M87 was generated from. By analyzing the VLBI data at 15 GHz from 2000 to 2009, we detected HST-1 during 2003 and 2007. We studied the apparent speed, the flux variability, and the spectral properties of HST-1. Although we found that the light curve of the compact HST-1 region at VLBA 15 GHz peaked in 2005, we saw that the HST-1 region was very extended and had a steep spectrum; the projected apparent speed of HST-1 was subluminal. Therefore, our results do not completely support the hypothesis. Studying multiband flares is one of the best ways to distinguish different mechanisms taken place in AGN. Current jet models suggest that time delays between multiband flares have different features while the emission mechanism differs. In this thesis, we studied the flat spectrum radio quasar PKS 2052-47, which experienced an optical flare followed by a gamma-ray flare in July 2009. We arranged a multiwavelength campaign from radio to gamma-ray after the blazar's flare. In the campaign, VLBI observations by the TANAMI program are included in order to trace any change of jet morphology, if any; the millimeter radio flux density was measured by the APEX telescope; the optical and the X-ray band observations were obtained by the Swift UV/Optical telescope (UVOT) and X-ray telescope (XRT); the gamma-ray observations were obtained by the Fermi Large Area Telescope (LAT). We do not see significant change in the X-ray photon indices and fluxes during the 5-day Swift monitoring of the source. The broadband SED reflects the emission properties of AGN, and it shows the energy output in different wavebands. By simulating physical jet models and reconstructing the broadband SED, one can probe the emission mechanism, the jet composition, the magnetic field, the bulk velocity in jet, and the structure of AGN. The MOJAVE program has been monitoring 135 radio-bright, statistically-complete sample of AGN using the Very Long Baseline Array (VLBA) at 15 GHz for a decade, and the MOJAVE sample is consisted of mostly blazars, which are AGN as seen jet-on. The typical broadband SED of a blazar has a double-hump profile. It is believed that the lower-energy hump is caused by the synchrotron emission from the AGN jet, and the higher-energy hump is produced by the inverse-Compton (IC) up-scattering of the seed photons from the jet or other external sources. We constructed a broadband SED catalog from the radio to the gamma-ray band of the MOJAVE sample, and we applied polynomial fits to the observed data at the low and the high energy humps of the SED as a first approach to understand the properties of the sources. In this thesis, we try to understand the AGN puzzles by using different approaches. We contributed in understanding the emission nature of AGN with novel techniques and instruments, and our efforts help to make a step forward to reveal the whole picture

TEL/AML1 Fusion Gene in Childhood Acute Lymphoblastic Leukemia in Southern Taiwan

Chromosomal abnormalities are found in 80–90% of childhood cases of acute lymphoblastic leukemia (ALL). Leukemia-specific chromosome aberrations not only have prognostic value, but also provide important clues for further investigation into leukogenesis, leukemic cell transformation, and proliferation. This study used reverse transcriptase–polymerase chain reaction techniques to detect transcripts of the leukemia-specific chromosome fusion gene, TEL/AML1, and to monitor the expression levels of the TEL-AML1 fusion transcript in ALL patients at sequential intervals during their treatment course. Twenty-five ALL patients were enrolled, including 20 who were newly diagnosed and five in relapse. The incidence of the TEL/AML1 fusion gene in this study was 32%. The clinical features of our eight TEL/AML1-positive ALL cases were similar to those in other studies. Blotting analysis of the levels of the TEL-AML1 fusion transcript was used to detect minimal residual disease. Reduced levels of TEL/AML1 expression were found in four of the six patients whose bone marrow or peripheral blood samples were obtained after treatment. Further investigation with a larger sample size is warranted

Construction and Characterization of Insect Cell-Derived Influenza VLP: Cell Binding, Fusion, and EGFP Incorporation

We have constructed virus-like particles (VLPs) harboring hemagglutinin (HA), neuraminidase (NA), matrix protein 1 (M1) ,and proton channel protein (M2) using baculovirus as a vector in the SF9 insect cell. The size of the expressed VLP was estimated to be ~100 nm by light scattering experiment and transmission electron microscopy. Recognition of HA on the VLP surface by the HA2-specific monoclonal antibody IIF4 at acidic pH, as probed by surface plasmon resonance, indicated the pH-induced structural rearrangement of HA. Uptake of the particle by A549 mediated by HA-sialylose receptor interaction was visualized by the fluorescent-labeled VLP. The HA-promoted cell-virus fusion activity was illustrated by fluorescence imaging on the Jurkat cells incubated with rhodamine-loaded VLP performed at fusogenic pH. Furthermore, the green fluorescence protein (GFP) was fused to NA to produce VLP with a pH-sensitive probe, expanding the use of VLP as an antigen carrier and a tool for viral tracking

Manipulation of Rat Movement via Nigrostriatal Stimulation Controlled by Human Visually Evoked Potentials

Here, we report that the development of a brain-to-brain interface (BBI) system that enables a human user to manipulate rat movement without any previous training. In our model, the remotely-guided rats (known as ratbots) successfully navigated a T-maze via contralateral turning behaviour induced by electrical stimulation of the nigrostriatal (NS) pathway by a brain-computer interface (BCI) based on the human controller's steady-state visually evoked potentials (SSVEPs). The system allowed human participants to manipulate rat movement with an average success rate of 82.2% and at an average rat speed of approximately 1.9 m/min. The ratbots had no directional preference, showing average success rates of 81.1% and 83.3% for the left-and right-turning task, respectively. This is the first study to demonstrate the use of NS stimulation for developing a highly stable ratbot that does not require previous training, and is the first instance of a training-free BBI for rat navigation. The results of this study will facilitate the development of borderless communication between human and untrained animals, which could not only improve the understanding of animals in humans, but also allow untrained animals to more effectively provide humans with information obtained with their superior perception.11Ysciescopu

Uncertainty Modeling for Robustness Analysis of Control Upset Prevention and Recovery Systems

Formal robustness analysis of aircraft control upset prevention and recovery systems could play an important role in their validation and ultimate certification. Such systems (developed for failure detection, identification, and reconfiguration, as well as upset recovery) need to be evaluated over broad regions of the flight envelope and under extreme flight conditions, and should include various sources of uncertainty. However, formulation of linear fractional transformation (LFT) models for representing system uncertainty can be very difficult for complex parameter-dependent systems. This paper describes a preliminary LFT modeling software tool which uses a matrix-based computational approach that can be directly applied to parametric uncertainty problems involving multivariate matrix polynomial dependencies. Several examples are presented (including an F-16 at an extreme flight condition, a missile model, and a generic example with numerous crossproduct terms), and comparisons are given with other LFT modeling tools that are currently available. The LFT modeling method and preliminary software tool presented in this paper are shown to compare favorably with these methods

Characterizing clinical isolates of Acanthamoeba castellanii with high resistance to polyhexamethylene biguanide in Taiwan

AbstractBackground/PurposeAcanthamoeba keratitis (AK), a painful infectious corneal disease, is caused by the free-living pathogenic species Acanthamoeba. The symptoms include corneal infiltrate, epithelial, and stromal destruction, and loss of vision. Current treatment generally involves an hourly application of polyhexamethylene biguanide (PHMB) over a period of several days; however, even this is not entirely effective against all strains/isolates. The aims of this study were to confirm the existence of pathogenic strains in Taiwan which are highly resistant to drugs and to characterize the behavior of these strains.MethodsAn in vitro Acanthamoeba species culture platform was established to observe the effectiveness of treatment and chart the morphological changes that occur under the effects of drugs using a light microscope and time-lapse recording. Changes in gene expression were examined using reverse transcription polymerase chain reaction (RT-PCR) and real-time PCR.ResultsOver 90% of the standard strain cells (ATCC 30010) were lysed after being treated with PHMB for 1 hour; however, clinical isolates of Acanthamoeba castellanii that differed in their susceptibility to the treatment drug were only partly lysed. Following treatment with PHMB, National Cheng Kung University Hospital isolation B (NCKH_B) transformed into a pseudocyst under the effects of drug stress; however, National Cheng Kung University Hospital isolation D (NCKH_D), an isolate with higher tolerance for PHMB, did not transform.ConclusionOur results confirm the existence of clinical isolates of A. castellanii with high resistance to PHMB in Taiwan and present the alternative drug tolerance of A. castellanii in addition to the transformation of pseudocyst/cyst

Serologic Status for Pandemic (H1N1) 2009 Virus, Taiwan

We studied preexisting immunity to pandemic (H1N1) 2009 virus in persons in Taiwan. A total of 18 (36%) of 50 elderly adults in Taiwan born before 1935 had protective antibodies against currently circulating pandemic (H1N1) 2009 virus. Seasonal influenza vaccines induced antibodies that did not protect against pandemic (H1N1) 2009 virus