Evidence of a mis-aligned secondary bar in the Large Magellanic Cloud

Evidence of a mis-aligned secondary bar, within the primary bar of the Large Magellanic Cloud (LMC) is presented. The density distribution and the de-reddened mean magnitudes ($I_0$) of the red clump stars in the bar obtained from the OGLE II data are used for this study. The bar region which predominantly showed wavy pattern in the line of sight in \citet{a03} was located. These points in the X-Z plane delineate an S-shaped pattern, clearly indicating a mis-aligned bar. This feature is statistically significant and does not depend on the considered value of $I_0$ for the LMC center. The rest of the bar region were not found to show the warp or the wavy pattern. The secondary bar is found to be considerably elongated in the Z-direction, with an inclination of 66$^o$.5 $\pm$ 0$^o$.9, whereas the undisturbed part of the primary bar is found to have an inclination of 15$^o$.1 $\pm$ 2$^o$.7, such that the eastern sides are closer to us with respect to the western sides of both the bars. The PA$_{maj}$ of the secondary bar is found to be 108$^o$.4 $\pm$ 7$^o$.3. The streaming motions found in the H I velocity map close to the LMC center could be caused by the secondary bar. The recent star formation and the gas distribution in LMC could be driven by the mis-aligned secondary bar.Comment: 10 pages, to appear in ApJ Letter

Modeling and simulation: the paradigm shift for cohesive resource harnessing

This paper presents the details of a specialized framework developed for the teaching of the modeling and simulation course for postgraduate students in Universiti Putra Malaysia. The unique feature of the subject is that it requires students ability to gain knowledge in several fields and relate them aptly to the need of performance analysis. IT also demands acquiring skills to develop comprehensive tools using the principles of discrete event simulation. The developed framework focuses on student-centered learning of queuing analysis, the development of models and relating them to performance analysis, the specialized activities to derive discrete event simulation components, and output analysis. It also deals with the tool's impact on research within the area. The framework was evaluated in a course. It showed the ability to enhance the level of student's understanding and application of competency gained to research

Poetry's Afterthought: Kalidasa and the Experience of Reading

This dissertation concerns the reception of the poet Kalidasa (c. 4th century), one of the central figures in the Sanskrit literary tradition. Since the time he lived and wrote, Kalidasa’s works have provoked many responses of different kinds. I shall examine how three writers contributed to this vast tradition of reception: Kuntaka, a tenth-century rhetorician from Kashmir; Vedantadesika, a South Indian theologian who lived in the thirteenth and fourteenth centuries; and Sri Aurobindo, an Indian English writer of the late nineteenth and early twentieth centuries who started out as an anticolonial activist and later devoted his life to spiritual exercises. While these readers lived well after Kalidasa, they were all deeply invested in his poetry. I wish to understand why Kalidasa’s poetry continued to provoke extended responses in writing long after its composition. It is true that readers often use past literary texts to various ends of their own devising, just as they often fall victim to reading texts anachronistically. In contradistinction to such cases, the examples of reading I examine highlight the role that texts themselves, not just their charisma or the mental habits of their readers, can have in constituting the reading process. They therefore urge us to formulate a more robust understanding of textual reception, and to reconsider the contemporary practice of literary criticism

Star Clusters in the Magellanic Clouds-1: Parameterisation and Classification of 1072 Clusters in the LMC

We have introduced a semi-automated quantitative method to estimate the age and reddening of 1072 star clusters in the Large Magellanic Cloud (LMC) using the Optical Gravitational Lensing Experiment (OGLE) III survey data. This study brings out 308 newly parameterised clusters. In a first of its kind, the LMC clusters are classified into groups based on richness/mass as very poor, poor, moderate and rich clusters, similar to the classification scheme of open clusters in the Galaxy. A major cluster formation episode is found to happen at 125 +- 25 Myr in the inner LMC. The bar region of the LMC appears prominently in the age range 60 - 250 Myr and is found to have a relatively higher concentration of poor and moderate clusters. The eastern and the western ends of the bar are found to form clusters initially, which later propagates to the central part. We demonstrate that there is a significant difference in the distribution of clusters as a function of mass, using a movie based on the propagation (in space and time) of cluster formation in various groups. The importance of including the low mass clusters in the cluster formation history is demonstrated. The catalog with parameters, classification, and cleaned and isochrone fitted CMDs of 1072 clusters, which are available as online material, can be further used to understand the hierarchical formation of clusters in selected regions of the LMC.Comment: 19 pages, 19figures, published in MNRAS on August 16, 2016 Supplementary material is available in the MNRAS websit

Optimal two-stage filtering of elastograms

In ultrasound elastography, tissue axial strains are obtained through the differentiation of measured axial displacements. However, during the measurement process, the displacement signals are often contaminated with de-correlation noise caused by changes in the speckle pattern in the tissue. Thus, the application of the gradient operator on the displacement signals results in the presence of amplified noise in the axial strains, which severely obscures the useful information. The use of an effective denoising scheme is therefore imperative. In this paper, a method based on a two-stage consecutive filtering approach is proposed for the accurate estimation of axial strains. The presented method considers a cascaded system of a frequency filter and a time window, which are both designed such that the overall system operates optimally as a minimum variance estimator. Experimentation on simulated signals shows that the two-stage scheme employed in this study has good potential as a denoising method for ultrasound elastograms

Teacher Knowledge and Learning In-situ: A Case Study of the Long Division Algorithm

The aim of the study reported in this paper was to explore and enhance experienced school mathematics teachers’ knowledge of students’ thinking, as it is manifested in practice. Data were collected from records of classroom observations, interviews with participating teachers, and weekly teacher-researcher meetings organized in the school. In this paper, we discuss the mathematical challenges faced by a primary school teacher as she attempts to unpack the structure of the division algorithm, while teaching in a Grade 4 classroom. Through this case study, we exemplify how a focus on mathematical knowledge for teaching ‘in situ’ helped in triggering a change in the teacher’s well-formed knowledge and beliefs about the teaching and learning of the division algorithm, and related students’ capabilities. We argue that in the context of educational reform, an analysis of knowledge demands placed on the teacher helps in understanding and supporting teachers’ work

Comparison of CFD and DSMC Using Calibrated Transport Parameters

Hypersonic re-entry flows span a wide range of length scales where regions of both rarefied and continuum flow exist. Traditional computational fluid dynamics (CFD) techniques do not provide an accurate solution for the rarefied regions of such mixed flow fields. Although direct simulation Monte Carlo (DSMC) can be used to accurately capture both the continuum and rarefied features of mixed flow fields, they are computationally expensive when employed to simulate the low Knudsen number continuum regimes. Thus, a hybrid framework for seamlessly combining the two methodologies, CFD and DSMC, continues to be a topic of significant research effort. Ensuring consistency in the reaction kinetics and transport models employed within CFD and DSMC is a crucial requirement for obtaining a reliable solution from a hybrid framework for combined continuum/rarefied high speed flows. This paper represents one of the first studies to utilize the calibrated transport parameters developed to ensure consistency between CFD and DSMC solvers. The new variable soft sphere (VSS) parameters are compared to both previous standard variable hard sphere (VHS) parameters and also to solutions from the CFD transport properties that the new parameters were developed to reproduce

Optical/IR studies of Be stars in NGC 6834 with emphasis on two specific stars

We present optical and infrared photometric and spectroscopic studies of two Be stars in the 70--80-Myr-old open cluster NGC 6834. NGC 6834(1) has been reported as a binary from speckle interferometric studies whereas NGC 6834(2) may possibly be a gamma Cas-like variable. Infrared photometry and spectroscopy from the United Kingdom Infrared Telescope (UKIRT), and optical data from various facilities are combined with archival data to understand the nature of these candidates. High signal-to-noise near-IR spectra obtained from UKIRT have enabled us to study the optical depth effects in the hydrogen emission lines of these stars. We have explored the spectral classification scheme based on the intensity of emission lines in the $H$ and $K$ bands and contrasted it with the conventional classification based on the intensity of hydrogen and helium absorption lines. This work also presents hitherto unavailable UBV CCD photometry of NGC 6834, from which the evolutionary state of the Be stars is identified.Comment: Published in Research in Astronomy and Astrophysics, RAA 14 (2014) 1173-1192, 20 pages, 10 figure