An X-ray/optical study of the geometry and dynamics of MACS J0140.0-0555, a massive post-collision cluster merger

We investigate the physical properties, geometry and dynamics of the massive cluster merger MACS J0140.0-0555 (z=0.451) using X-ray and optical diagnostics. Featuring two galaxy overdensities separated by about 250 kpc in projection on the sky, and a single peak in the X-ray surface brightness distribution located between them, MACS J0140.0-0555 shows the tell-tale X-ray/optical morphology of a binary, post-collision merger. Our spectral analysis of the X-ray emission, as measured by our Chandra ACIS-I observation of the system, finds the intra-cluster medium to be close to isothermal (~8.5 keV) with no clear signs of cool cores or shock fronts. Spectroscopic follow-up of galaxies in the field of MACS J0140.0-0555 yields a velocity dispersion of 875 (+70/-100) km/s (n_z=66) and no significant evidence of bimodality or substructure along the line of sight. In addition, the difference in radial velocity between the brightest cluster galaxies of the two sub-clusters of 144+/-25 km/s is small compared to typical collision velocities of several 1000 km/s. A strongly lensed background galaxy at z=0.873 (which features variable X-ray emission from an active nucleus) provides the main constraint on the mass distribution of the system. We measure M(<75 kpc) = (5.6+/- 0.5)*10^13 M_sun for the north-western cluster component and a much less certain estimate of (1.5-3)*10^13 M_sun for the south-eastern subcluster. These values are in good agreement with our X-ray mass estimates which yield a total mass of MACS J0140.0-0555 of M(<r_500) ~ (6.8-9.1)*10^14 M_sun. ......Comment: 11 pages, 8 figures, and 2 tables. Accepted for publication in MNRA

Multiple Radial Cool Molecular Filaments in NGC 1275

We have extended our previous observation (Lim et al. 2008) of NGC1275 covering a central radius of ~10kpc to the entire main body of cool molecular gas spanning ~14kpc east and west of center. We find no new features beyond the region previously mapped, and show that all six spatially-resolved features on both the eastern and western sides (three on each side) comprise radially aligned filaments. Such radial filaments can be most naturally explained by a model in which gas deposited "upstream" in localized regions experiencing an X-ray cooling flow subsequently free falls along the gravitational potential of PerA, as we previously showed can explain the observed kinematics of the two longest filaments. All the detected filaments coincide with locally bright Halpha features, and have a ratio in CO(2-1) to Halpha luminosity of ~1e-3; we show that these filaments have lower star formation efficiencies than the nearly constant value found for molecular gas in nearby normal spiral galaxies. On the other hand, some at least equally luminous Halpha features, including a previously identified giant HII region, show no detectable cool molecular gas with a corresponding ratio at least a factor of ~5 lower; in the giant HII region, essentially all the pre-existing molecular gas may have been converted to stars. We demonstrate that all the cool molecular filaments are gravitationally bound, and without any means of support beyond thermal pressure should collapse on timescales ~< 1e6yrs. By comparison, as we showed previously the two longest filaments have much longer dynamical ages of ~1e7yrs. Tidal shear may help delay their collapse, but more likely turbulent velocities of at least a few tens km/s or magnetic fields with strengths of at least several ~10uG are required to support these filaments.Comment: 52 pages, 11 figures. Accepted to Ap

A Machine Learning Artificial Neural Network Calibration of the Strong-Line Oxygen Abundance

The HII region oxygen abundance is a key observable for studying chemical properties of galaxies. Deriving oxygen abundances using optical spectra often relies on empirical strong-line calibrations calibrated to the direct method. Existing calibrations usually adopt linear or polynomial functions to describe the non-linear relationships between strong line ratios and Te oxygen abundances. Here, I explore the possibility of using an artificial neural network model to construct a non-linear strong-line calibration. Using about 950 literature HII region spectra with auroral line detections, I build multi-layer perceptron models under the machine learning framework of training and testing. I show that complex models, like the neural network, are preferred at the current sample size and can better predict oxygen abundance than simple linear models. I demonstrate that the new calibration can reproduce metallicity gradients in nearby galaxies and the mass-metallicity relationship. Finally, I discuss the prospects of developing new neural network calibrations using forthcoming large samples of HII region and also the challenges faced.Comment: 12 pages, 15 figures. Accepted to MNRA

Culturally Diverse and Underserved Populations of Gifted Students In the United States and in Taiwan: Equitable Access to Gifted Education

There is a continuing increase in the African American and Hispanic student populations in public schools. The students who are invited to gifted programs are overwhelmingly White. This is the situation in schools in the United States and also in Taiwan. Misunderstanding or unawareness of culture difference among educators might contribute to underrepresentation of minority students in gifted programs. The research literature reviewed indicates that a deficit in orientation, ineffective teacher referral policies, and the use of culturally biased assessments are the major reasons responsible for low rates of identification for gifted minority students. The purpose of this thesis is to explore more effective strategies to identify, or to increase awareness of gifted minority students and provide them equitable access to gifted education. The researcher interviewed six teachers of the gifted program to collect information in the United States and in Taiwan related to underrepresented minority students in gifted education programs. According to the results, the researcher generalized four key reasons of disparity in the gifted program: definition of giftedness, family factors, identification procedure and instruments, and curriculum and instruction

Distorting your perception of Russia’s aggression: how can we combat information warfare?

Despite the brutality of the Russian invasion of Ukraine, support or sympathy toward Russia is shown by some actors on the international stage. This could be attributed to the multi-facet information warfare conducted by Russia and its strategic partner China. However, the analysis of information warfare during the current war remains scattered. This article, therefore, adopts a documentary analysis of relevant documents and media sources to conceptualize the forms of information warfare used by these two countries to contribute to future studies. It then proceeds to discuss that the Russia-Ukraine war implies a growing use of information warfare in present and future wars under digitalization. Facing a growing threat posed to people’s cognitive understanding, the democratic community has to be aware of this increasingly dangerous military strategy and develop corresponding solutions. This article suggests that different societal stakeholders must collaborate to develop comprehensive education and thus strengthen digital citizenship. This is vital to nurturing people into critical and responsible citizens, thus equipping themselves with the resilience needed to combat information warfare

Taking Note: A Design Solution for Physician Documentation to Balance the Benefits of Handwritten Notes and Electronic Health Records

Master of Design in Integrative DesignUniversity of Michiganhttps://deepblue.lib.umich.edu/bitstream/2027.42/136865/1/THo_2017_MDes-Thesis.pd

How large is the potential market of microwave food in China?

In China, food industry brings huge profit in every year, but the microwave food industry still faces the problem of underdevelopment. To explore the extent of the potential market of microwave food, a research on it can be contributed. However, there are rare similar researches on the circumstances of microwave food in China, so it is valuable to design a research project which particularly focuses on the mainland conditions of microwave food. Shanghai is one of the most desirable places among the major mainland cities. Thus, its market of microwave food can perform as a model for other cities to develop a wider and sustainable expansion in the entire mainland market. To study the microwave food’s market in China, we will gather and analyze the information about the trend of microwave food and the effect of demographic and sociocultural factors on the growth of microwave food in Shanghai from primary and secondary sources. For the primary source, a survey was conducted and 150 samples were collected. We try to analyze our research hypotheses through the survey and useful data was collected. Besides, the secondary information was also collected through the Internet, books, journals, etc. With the information, we will analyze the circumstances of mainland food market, describe the environment factors in Shanghai and its current status of food market, and use the case study to predict the growing phenomenon of microwave food in China. We hope that this research can contribute in creating a favorable environment of microwave food market for the future and designing an appropriate strategy to implement into the microwave food industry. Besides, the potential for microwave ready meals in this convenience-led society is a huge opportunity for manufacturers. Consequently, they can gain an appreciable return through the development of microwave food in China. As an effectual marketing strategy should be designed for a specific company, we choose the famous frozen food company in Hong Kong, Tao Fa, Amoy. We take it as an example and suggest the marketing plan for its development of microwave food in China

The Dissimilar Effects of Fairness on Knowledge Sharing in Distributed Workgroups: A Social Network Perspective

Distributed workgroups are increasingly adopted by global organizations, enabled by technology advances. While social ties and performance of such workgroups have been examined in existing literature, the distinctions in knowledge sharing practices remain blurred. We developed a research model to examine the effects of social ties on knowledge sharing practices through the lens of justice perceptions (i.e., fairness) from a dyadic level. The model was tested in a field study of distributed workgroups at a large multinational organization. Our results suggested that Simmelian-tied dyads (dyads embedded in three-person cliques) had significant influence on justice perceptions and knowledge sharing. Expertise knowledge sharing was influenced by procedural and informational justice perceptions. Contrary to previous studies, our study suggested that product knowledge sharing occurred regardless of distributive justice perception. The findings provided insights to the mechanisms underlying social ties, justice perceptions, and knowledge sharing