1,055 research outputs found
Sizes and Kinematics of Extended Narrow-Line Regions in Luminous Obscured AGN Selected by Broadband Images
To study the impact of active galactic nuclei (AGN) feedback on the galactic
ISM, we present Magellan long-slit spectroscopy of 12 luminous nearby type 2
AGN (L_bol~10^{45.0-46.5} erg/s, z~0.1). These objects are selected from a
parent sample of spectroscopically identified AGN to have high
[OIII]{\lambda}5007 and WISE mid-IR luminosities and extended emission in the
SDSS r-band images, suggesting the presence of extended [OIII]{\lambda}5007
emission. We find spatially resolved [OIII] emission (2-35 kpc from the
nucleus) in 8 out of 12 of these objects. Combined with samples of higher
luminosity type 2 AGN, we confirm that the size of the narrow-line region
(R_NLR) scales with the mid-IR luminosity until the relation flattens at ~10
kpc. Nine out of 12 objects in our sample have regions with broad [OIII]
linewidths (w_80>600 km/s), indicating outflows. We define these regions as the
kinematically-disturbed region (KDR). The size of the KDR (R_KDR) is typically
smaller than R_NLR by few kpc but also correlates strongly with the AGN mid-IR
luminosity. Given the unknown density in the gas, we derive a wide range in the
energy efficiency {\eta}=dot{E}/L_bol=0.01%-30%. We find no evidence for an AGN
luminosity threshold below which outflows are not launched. To explain the
sizes, velocity profiles, and high occurrence rates of the outflows in the most
luminous AGN, we propose a scenario in which energy-conserving outflows are
driven by AGN episodes with ~10^8-year durations. Within each episode the AGN
flickers on shorter timescales, with a cadence of ~10^6 year active phases
separated by ~10^7 years.Comment: 32 pages, 21 figures, ApJ in revie
ALMA Observations of a Candidate Molecular Outflow in an Obscured Quasar
We present Atacama Large Millimeter/Submillimeter Array (ALMA) CO (1-0) and
CO (3-2) observations of SDSS J135646.10+102609.0, an obscured quasar and
ultra-luminous infrared galaxy (ULIRG) with two merging nuclei and a known
20-kpc-scale ionized outflow. The total molecular gas mass is M_{mol} ~
9^{+19}_{-6} x 10^8 Msun, mostly distributed in a compact rotating disk at the
primary nucleus (M_{mol} ~ 3 x 10^8 Msun) and an extended tidal arm (M_{mol} ~
5 x 10^8 Msun). The tidal arm is one of the most massive molecular tidal
features known; we suggest that it is due to the lower chance of shock
dissociation in this elliptical/disk galaxy merger. In the spatially resolved
CO (3-2) data, we find a compact (r ~ 0.3 kpc) high velocity (v ~ 500 km/s)
red-shifted feature in addition to the rotation at the N nucleus. We propose a
molecular outflow as the most likely explanation for the high velocity gas. The
outflowing mass of M_{mol} ~ 7 x 10^7 Msun and the short dynamical time of
t_{dyn} ~ 0.6 Myr yield a very high outflow rate of \dot{M}_{mol} ~ 350 Msun/yr
and can deplete the gas in a million years. We find a low star formation rate
(< 16 Msun/yr from the molecular content and < 21 Msun/yr from the far-infrared
spectral energy distribution decomposition) that is inadequate to supply the
kinetic luminosity of the outflow (\dot{E} ~ 3 x 10^43 erg/s). Therefore, the
active galactic nucleus, with a bolometric luminosity of 10^46 erg/s, likely
powers the outflow. The momentum boost rate of the outflow (\dot{p}/(Lbol/c) ~
3) is lower than typical molecular outflows associated with AGN, which may be
related to its compactness. The molecular and ionized outflows are likely two
distinct bursts induced by episodic AGN activity that varies on a time scale of
10^7 yr.Comment: 16 pages, 7 figures, ApJ accepte
CIRCUitS
The purpose of this design research was to explore the integration of wearable light-emitting diode (LED) elements with traditional garment/accessory embellishment and construction techniques. Tacit knowledge of circus costuming involving wearable LED tech informed the basis of the research, and couture beading techniques were employed alongside LED application. The ensemble of a metallic brocade coatdress with contrast lining and complementing top hat utilized LED circuitry to illuminate a beaded appliqué on the back of the coatdress. LEDs along the underside of the hat\u27s brim cast light onto the beading, complementing LEDs residing underneath the beaded appliqué. Adaptations to existing computer code were employed to adjust the LED programming via an Adafruit FLORA microprocessor, and design challenges resulted due to the designer\u27s lack of prior knowledge of computer programming. Safety measures against electrocution and conductivity were employed in the form of insulating layers and careful stitching of conductive threads
Extended X-ray Emission From a Quasar-Driven Superbubble
We present observations of extended, 20-kpc scale soft X-ray gas around a
luminous obscured quasar hosted by an ultra-luminous infrared galaxy caught in
the midst of a major merger. The extended X-ray emission is well fit as a
thermal gas with a temperature of kT ~ 280 eV and a luminosity of L_X ~ 10^42
erg/s and is spatially coincident with a known ionized gas outflow. Based on
the X-ray luminosity, a factor of ~10 fainter than the [OIII] emission, we
conclude that the X-ray emission is either dominated by photoionization, or by
shocked emission from cloud surfaces in a hot quasar-driven wind.Comment: Accepted for publication in ApJ, 6 pages, 2 figure
Oxidative stress alters cell morphology and cell death indices in immortalized astrocytes
Abstract only availableMenadione, usually known as vitamin K3, also serves as a trigger for oxidative stress, delivering reactive oxygen species (ROS) upon entering the cells. Astrocytes are glial cells that are found in the brain and are extremely important in providing nourishment to cells in the brain, especially neurons. Oxidative stress may cause damage to astrocytes and alter their function. Increase in oxidative stress is the underlying cause for many neurodegenerative diseases like Alzheimer's disease and stroke. In this study, we used menadione as an oxidant compound to study effects of oxidative stress on cell morphology and viability in an immortalized astrocyte cell line (DITNC). Menadione causes cytoskeletal rearrangement and stress fiber protrusions in astrocytes. This event is accomplished by an increase in LDH release and a decrease in MTT release, suggesting loss of cell viability. Resveratrol (enriched in grape) and curcumin (from turmeric), polyphenolic antioxidants, have been shown to inhibit damage caused by ROS. In this study, we also used these botanical compounds to demonstrate their inhibitory properties against menadione-mediated morphological changes and cell damage in DITNC cells.NSF-REU Biology & Biochemistr
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Naïve Bayesian Classifier and Genetic Risk Score for Genetic Risk Prediction of a Categorical Trait: Not so Different after all!
One of the most popular modeling approaches to genetic risk prediction is to use a summary of risk alleles in the form of an unweighted or a weighted genetic risk score, with weights that relate to the odds for the phenotype in carriers of the individual alleles. Recent contributions have proposed the use of Bayesian classification rules using Naïve Bayes classifiers. We examine the relation between the two approaches for genetic risk prediction and show that the methods are mathematically related. In addition, we study the properties of the two approaches and describe how they can be generalized to include various models of inheritance
Refining the M_BH-V_c scaling relation with HI rotation curves of water megamaser galaxies
Black hole - galaxy scaling relations provide information about the
coevolution of supermassive black holes and their host galaxies. We compare the
black hole mass - circular velocity (MBH - Vc) relation with the black hole
mass - bulge stellar velocity dispersion (MBH - sigma) relation, to see whether
the scaling relations can passively emerge from a large number of mergers, or
require a physical mechanism, such as feedback from an active nucleus. We
present VLA H I observations of five galaxies, including three water megamaser
galaxies, to measure the circular velocity. Using twenty-two galaxies with
dynamical MBH measurements and Vc measurements extending to large radius, our
best-fit MBH - Vc relation, log MBH = alpha + beta log(Vc /200 km s^-1), yields
alpha = 7.43+/-0.13, beta = 3.68+1.23/-1.20, and intrinsic scatter epsilon_int
= 0.51+0.11/-0.09. The intrinsic scatter may well be higher than 0.51, as we
take great care to ascribe conservatively large observational errors. We find
comparable scatter in the MBH - sigma relations, epsilon_int = 0.48+0.10/-0.08,
while pure merging scenarios would likely result in a tighter scaling with the
dark halo (as traced by Vc) than baryonic (sigma) properties. Instead, feedback
from the active nucleus may act on bulge scales to tighten the MBH - sigma
relation with respect to the MBH - Vc relation, as observed.Comment: 27 pages, 15 figures, ApJ accepte
Optical imaging and stimulation systems for engineered human cardiac tissues
Heart disease is the leading cause of death in the world. Finding future therapeutics for heart disease requires the development of mature 3D engineered human cardiac tissues that can serve as reliable models for biological studies and drug development. The ability to measure and stimulate cardiac action potentials (APs) is key to the development of these 3D tissue models.
Optical measurement and stimulation methods offer an enticing solution to longstanding tissue development testbed needs. However, existing optical measurement methods have relied on toxic voltage dyes and motion inhibiting drugs, and existing optical stimulation methods have mainly focused on optogenetic modification techniques.
In this dissertation, I present two related optical systems built for 3D engineered human cardiac microtissues, organized into two chapters: 1) a dual-mode voltage and contraction imaging optical microscope for tracking action potential metrics with fluorescent genetically encoded voltage indicator Archon1, and 2) an all optical cardiac stimulation system for unmodified engineered human cardiac micro-tissues with red and blue laser pulse options. These systems offer cardiac researchers less invasive optical solutions for cardiac action potential visualization and pacing: the microscope system allows direct action potential measurements without the use of toxic dyes, and the stimulation system allows ex-vivo pacing without any modification to the sample, genetic or otherwise. I will discuss the system design motivations, challenges, results, and mechanisms of this work
Morphology of AGN Emission Line Regions in SDSS-IV MaNGA Survey
Extended narrow-line regions (NLRs) around active galactic nuclei (AGN) are
shaped by the distribution of gas in the host galaxy and by the geometry of the
circumnuclear obscuration, and thus they can be used to test the AGN
unification model. In this work, we quantify the morphologies of the
narrow-line regions in 308 nearby AGNs (, \lbol
\erg{}) from the MaNGA survey. Based on the narrow-line region maps, we find
that a large fraction (81\%) of these AGN have bi-conical NLR morphology. The
distribution of their measured opening angles suggests that the intrinsic
opening angles of the ionization cones has a mean value of 85--98 with
a finite spread of 39-44 (1-). Our inferred opening angle
distribution implies a number ratio of type I to type II AGN of 1:1.6--2.3,
consistent with other measurements of the type I / type II ratio at low AGN
luminosities. Combining these measurements with the WISE photometry data, we
find that redder mid-IR color (lower effective temperature of dust) corresponds
to stronger and narrower photo-ionized bicones. This relation is in agreement
with the unification model that suggests that the bi-conical narrow-line
regions are shaped by a toroidal dusty structure within a few pc from the AGN.
Furthermore, we find a significant alignment between the minor axis of host
galaxy disks and AGN ionization cones. Together, these findings suggest that
obscuration on both circumnuclear (pc) and galactic ( kpc) scales
are important in shaping and orienting the AGN narrow-line regions.Comment: 14 pages, 7 figures, and 1 table, accepted for publication in MNRA
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