A New Mass Estimate of the Central Supermassive Black Hole in NGC 4051 with Reverberation Mapping

Mathematical and Physical Sciences: 1st Place (The Ohio State University Edward F. Hayes Graduate Research Forum)There is increasingly strong evidence from observations of the local universe that every galaxy hosts a black hole at its center with a mass of hundreds of thousands to millions of times the mass of the sun.  It is also becoming clear that these supermassive' black holes are connected to the evolution of galaxies. Therefore, understanding how galaxies form requires an understanding of the demographics of their central black holes. One of the few direct methods of measuring black hole masses in distant galaxies is to apply a technique known as reverberation mapping to objects that are actively accreting matter (active galactic nuclei or AGNs) and for which we have a generally unobscured view of the galactic nucleus (type 1 AGNs). Reverberation mapping takes advantage of an observed time delay between brightness fluctuations in light originating from a continuum source very near the black hole (the hot accretion disk) and broad emission lines (i.e., resolved in Doppler velocity) that are produced by rapidly moving gas in the vicinity of the nucleus, the broad-line emitting region (BLR).  If the BLR gas is in virial equilibrium and under gravitational influence of the supermassive black hole, the velocity of the BLR gas, measured from the widths of broad emission lines, and the BLR radius are related through the mass of the black hole itself.  Long observing campaigns monitor the continuum and emission-line brightness variations to measure the time delay, t, which corresponds to the light travel time across the BLR. Measurements of t then allow for an estimate of the size of the region, R_BLR = c*t, with which we can then estimate the black hole mass.  We present the first results from a multi-month reverberation mapping campaign undertaken primarily at MDM Observatory but with supporting observations from telescopes around the world.  We feature the results for NGC 4051 because it was previously found to be a significant outlier from the relationship between the BLR radius and the optical continuum luminosity, the R_BLR-L relationship, found for other AGNs.  We measure a relatively small BLR radius and thus black hole mass for NGC 4051 that would have been impossible for past studies to resolve because the variations were previously undersampled. Our new results indicate that this AGN is actually completely consistent with the R_BLR-L relationship, thus resolving the previous discrepancy and strengthening the evidence for the homologous nature of AGNs --- an exciting interpretation of the tightness of the R_BLR-L relationship, given the diverse demographics of galaxies.No embarg

Influence of Feedback and Comment Labels on Information Sharing in a Computer Mediated Collaborative Environment

A group support system (GSS) uses a combination of networked personal computers, software, and human facilitation to improve the group decision-making process. Group support Systems are being used in the Air Force today in a variety of capacities and in particular by the Warner-Robins Air Logistics Center (WR-ALC) to assess acquisition risks. Prior GSS research has found that certain structural and social dimensions of GSS designs might influence whether optimal process improvements take place. However, the dimensions that positively influence group performance have continued to be a matter of debate. This thesis looked at several structural and social contingencies to explore possible explanations for the mixed results found in GSS research. The study examined the effect of: anonymity, identification, self-regulation, and facilitator provided feedback on user information sharing behavior, quality of the group decision, unequal participation among group members, and user attitudes with the GSS meeting. The results of the study indicated that the anonymity theory was partially supported since users in an anonymous condition provided more intellective comments than any other condition. In addition, the self-regulation theory was partially supported since users were found to have more satisfaction with the GSS meeting in this treatment

High Redshift Standard Candles: Predicted Cosmological Constraints

We investigate whether future measurements of high redshift standard candles (HzSCs) will be a powerful probe of dark energy, when compared to other types of planned dark energy measurements. Active galactic nuclei and gamma ray bursts have both been proposed as potential HzSC candidates. Due to their high luminosity, they can be used to probe unexplored regions in the expansion history of the universe. Information from these regions can help constrain the properties of dark energy, and in particular, whether it varies over time. We consider both linear and piecewise parameterizations of the dark energy equation of state, $w(z)$, and assess the optimal redshift distribution a high-redshift standard-candle survey could take to constrain these models. The more general the form of the dark energy equation of state $w(z)$ being tested, the more useful high-redshift standard candles become. For a linear parameterization of $w(z)$, HzSCs give only small improvements over planned supernova and baryon acoustic oscillation measurements; a wide redshift range with many low redshift points is optimal to constrain this linear model. However to constrain a general, and thus potentially more informative, form of $w(z)$, having many HzSCs can significantly improve limits on the nature of dark energy.Comment: Accepted MNRAS, 27 Pages, 15 figures, matches published versio

The political economy of trade policy in the KORUS FTA

This is an abridged version of the winner of the best paper award at the 2011 Seoul inter-GSIS competition at the Korean Institute for International Economic Policy (KIEP). The full and original paper can be found here

The Importance of Broad Emission-Line Widths in Single Epoch Black Hole Mass Estimates

Estimates of the mass of super-massive black holes (BHs) in distant active galactic nuclei (AGNs) can be obtained efficiently only through single-epoch spectra, using a combination of their broad emission-line widths and continuum luminosities. Yet the reliability and accuracy of the method, and the resulting mass estimates, M_BH, remain uncertain. A recent study by Croom using a sample of SDSS, 2QZ and 2SLAQ quasars suggests that line widths contribute little information about the BH mass in these single-epoch estimates and can be replaced by a constant value without significant loss of accuracy. In this Letter, we use a sample of nearby reverberation-mapped AGNs to show that this conclusion is not universally applicable. We use the bulge luminosity (L_Bulge) of these local objects to test how well the known M_BH - L_Bulge correlation is recovered when using randomly assigned line widths instead of the measured ones to estimate M_BH. We find that line widths provide significant information about M_BH, and that for this sample, the line width information is just as significant as that provided by the continuum luminosities. We discuss the effects of observational biases upon the analysis of Croom and suggest that the results can probably be explained as a bias of flux-limited, shallow quasar samples.Comment: 10 text pages + 4 Figures + 1 Table. Accepted for publication in ApJ Letter

Data Center Security: Analysis of Two Audit Reports

The increasing volume of electronic data, the need for secure storage of this data and the necessity for organizations to prepare for disaster are key reasons promoting the prominence of data centers in our society. Since data centers house large volumes of valuable information, proper security of organizational data centers is essential. This paper provides the reader with an overview of security principles relevant to data centers. We then offer a synopsis, aggregation and exploratory analysis of two audit reports of government data centers in the United States. We suggest general observations from the audit reports before concluding. As a contribution to the literature, this paper offers an investigative analysis of data center audits that can form a baseline for a more thorough future study on this relevant topic

Comprehensiveness of infant formula and bottle feeding resources: A review of information from Australian healthcare organisations.

The use of infant formula is widespread internationally. In Australia, 55% of infants receive formula before 6 months of age, with higher rates among disadvantaged communities. Infant formula use can contribute to childhood overweight and obesity, through formula composition and feeding behaviours, such as adding cereal to bottles and parental feeding style. While information abounds to promote and support breastfeeding, formula-feeding parents report a paucity of advice and support; many rely on formula packaging for information. This study systematically searched and reviewed online resources for infant formula and bottle feeding from Australian governments, health services, hospitals, and not-for-profit parenting organisations. A comprehensive search strategy located 74 current resources, mostly for parents. Researchers evaluated the resources against best practice criteria derived from Australian government and UNICEF guidelines on six topics. They assessed how comprehensively the resources addressed each topic and whether the resources provided all the information necessary for parents to understand each topic. The mean 'comprehensiveness' rating for topics across all resources was 54.36%. However, some topics were addressed more fully than others. Information on 'discussing infant formula with health workers' and on 'preparing infant formula' was more frequently accurate and comprehensive. However, there was much less comprehensive information on 'using infant formula', including amounts of formula to feed, use of bottle teats, appropriate bottle-feeding practice and responsiveness to infant satiety cues. Over half the resources were written at an acceptable reading level

A programmable SDN+NFV-based architecture for UAV telemetry monitoring

The explosive growth in the worldwide use of Unmanned Aerial Vehicles (UAVs) has raised a critical concern with respect to the adequate management of their ad hoc network configuration as required by their mobility management process. As UAVs migrate among ground control stations, associated network services, routing and operational control must also rapidly migrate to ensure a seamless transition. In this paper, we present a novel, lightweight and modular architecture which supports high mobility and situational-awareness through the application of Software Defined Networking (SDN) and Network Function Virtualization (NFV) principles on top of the UAV infrastructure. By combining SDN+NFV programmability we can achieve a robust migration of UAV-related network services, such as network monitoring and anomaly detection as well as smooth UAV migration that confronts high mobility requirements. The proposed container-based monitoring and anomaly detection Network Functions (NFs) as employed within our architecture can be tuned to specific UAV types providing operators better insight during live, high-mobility deployments. We evaluate our architecture against telemetry from over 80 flights from a scientific research UAV infrastructure showing our ability to tune and detect emerging challenges

Influences on consumption of soft drinks and fast foods in adolescents

Soft drink and fast food are energy dense foodstuffs that are heavily marketed to adolescents, and are likely to be important in terms of risk of obesity. This study sought to examine the influences on soft drink and fast food consumption among adolescents as part of a cross-sectional survey of 2,719 adolescents (aged 11-16) from 93 randomly selected schools in New South Wales, Australia. Students provided information on soft drink and fast food consumption, and responded to statements examining influences over consumption. Over half of the boys and more than one third of the girls reported drinking soft drink daily, and consumption peaked in Grade 8 students. A quarter of students reported choosing soft drinks instead of water or milk, and around 40% agreed that soft drink was usually available in their homes. Availability in the home and drinking soft drinks with meals was most strongly associated with consumption in all age groups. Fast food consumption was higher among boys than girls in all age groups. Convenience and value for money yielded the strongest associations with fast foodconsumption in boys, while preferring fast food to meals at home and preferring to &ldquo;upsize&rdquo; meals were most strongly associated with consumption in girls. Interventions to reduce consumption of soft drinks should target availability in both the home and school environment by removing soft drinks and replacing them with more nutritive beverages. Fast food outlets should be encouraged to provide a greater range of healthy and competitively priced options in reasonable portions.<br /