X-ray to NIR emission from AA Tauri during the dim state - Occultation of the inner disk and gas-to-dust ratio of the absorber

AA Tau is a well-studied, nearby classical T Tauri star, which is viewed almost edge-on. A warp in its inner disk periodically eclipses the central star, causing a clear modulation of its optical light curve. The system underwent a major dimming event beginning in 2011 caused by an extra absorber, which is most likely associated with additional disk material in the line of sight toward the central source. We present new XMM-Newton X-ray, Hubble Space Telescope FUV, and ground based optical and near-infrared data of the system obtained in 2013 during the long-lasting dim phase. The line width decrease of the fluorescent H$_2$ disk emission shows that the extra absorber is located at $r>1\,$au. Comparison of X-ray absorption ($N_H$) with dust extinction ($A_V$), as derived from measurements obtained one inner disk orbit (eight days) after the X-ray measurement, indicates that the gas-to-dust ratio as probed by the $N_H$ to $A_V$ ratio of the extra absorber is compatible with the ISM ratio. Combining both results suggests that the extra absorber, i.e., material at $r>1\,$au, has no significant gas excess in contrast to the elevated gas-to-dust ratio previously derived for material in the inner region ($\lesssim0.1\,$au).Comment: 16 pages, 12 figures, accepted by A&

Detection of Attribute Hierarchies and Classification Accuracy: the Value of the Hierarchical Diagnostic Classification Model in Formative Assessment Practices

The assumption that learning occurs sequentially, or in steps, is a common consideration in K12 education. As the landscape of student education continues to advance, driven by efforts to incorporate tools that offer educators and students feedback capable of identifying areas a student is excelling or struggling in, cognitive diagnostic models are emerging as potentially effective and efficient tools. Despite the value of diagnostic models, there are concerns regarding the application of these models when as learning hierarchy is present or theorized; applying nonhierarchical cognitive diagnostic models when an attribute hierarchy is present or applying hierarchical cognitive diagnostic models when an attribute hierarchy is not present influences the classification accuracy of the models. This study was designed to evaluate the efficiency of the HDCM in statistically testing for an attribute hierarchy, therein providing researchers with evidence and support for subsequent model application. By evaluating the results from a formative assessment designed based on the structure of a theorized attribute hierarchy, this study highlighted the model fit variations and student classification differences. The results of this study indicate that the HDCM does in fact provide a means for researchers to investigate the presence of a theorized hierarchy. Additionally, this study highlights the potential classification differences noted between models

Correspondence to General William Robertson Boggs, 1890s: March 7, 1892 - October 1, 1899.

Boggs Family Papers, Box 1, Folder 5. Correspondence to General William Robertson Boggs, 1890s: March 7, 1892 - October 1, 1899.https://digitalcommons.wofford.edu/littlejohnboggs/1004/thumbnail.jp

Concept of operations for data fusion visualization

Situational awareness in the operations and supervision of a industrial system means that decision making entity, whether machine or human, have the important data presented in a timely manner. An optimal presentation of information such that the operator has the best opportunity accurately interpret and react to anomalies due to system degradation, failures or adversaries. Anticipated problems are a matter for system design; however, the paper will focus on concepts for situational awareness enhancement for a human operator when the unanticipated or unaddressed event types occur. Methodology for human machine interface development and refinement strategy is described for a synthetic fuels plant model. A novel concept for adaptively highlighting the most interesting information in the system and a plan for testing the methodology is described

A UV-to-NIR Study of Molecular Gas in the Dust Cavity around RY Lupi

We present a study of molecular gas in the inner disk (r ∼ 0.4± 0.1 au; {r(narrow,H₂)} ∼ 3± 2 au). The 4.7 μm ¹²CO emission lines are also well fit by two-component profiles ( {{r}broad,CO} =0.4± 0.1 au; {{r}narrow,CO} =15± 2 au). We combine these results with 10 μm observations to form a picture of gapped structure within the mm-imaged dust cavity, providing the first such overview of the inner regions of a young disk. The HST SED of RY Lupi is available online for use in modeling efforts