G51.04+0.07 and its environment: Identification of a new Galactic supernova remnant at low radio frequencies

We have identified a new supernova remnant (SNR), G51.04+0.07, using observations at 74 MHz from the Very Large Array Low-Frequency Sky Survey Redux (VLSSr). Earlier, higher frequency radio continuum, recombination line, and infrared data had correctly inferred the presence of nonthermal radio emission within a larger, complex environment including ionised nebulae and active star formation. However, our observations have allowed us to redefine at least one SNR as a relatively small source (7.05 × 30in size) located at the southern periphery of the originally defined SNR candidate G51.21+0.11. The integrated flux density of G51.04+0.07 at 74 MHz is 6.1 ± 0.8 Jy, while its radio continuum spectrum has a slope α = −0.52 ± 0.05 (Sν ∝ να), typical of a shell-type remnant. We also measured spatial variations in the spectral index between 74 and 1400 MHz across the source, ranging from a steeper spectrum (α = −0.50 ± 0.04) coincident with the brightest emission to a flatter component (α = −0.30 ± 0.07) in the surrounding fainter region. To probe the interstellar medium into which the redefined SNR is likely evolving, we have analysed the surrounding atomic and molecular gas using the 21 cm neutral hydrogen (HI) and 13CO(J = 1 − 0) emissions. We found that G51.04+0.07 is confined within an elongated HI cavity and that its radio emission is consistent with the remains of a stellar explosion that occurred ∼6300 yr ago at a distance of 7.7 ± 2.3 kpc. Kinematic data suggest that the newly discovered SNR lies in front of HII regions in the complex, consistent with the lack of a turnover in the low frequency continuum spectrum. The CO observations revealed molecular material that traces the central and northern parts of G51.04+0.07. The interaction between the cloud and the radio source is not conclusive and motivates further study. The relatively low flux density (∼1.5 Jy at 1400 MHz) of G51.04+0.07 is consistent with this and many similar SNRs lying hidden along complex lines of sight towards inner Galactic emission complexes. It would also not be surprising if the larger complex studied here hosted additional SNRs.Fil: Supán, Jorge Leonardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Castelletti, Gabriela Marta. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Peters, W. M.. Spece Sciences División. Naval Research Laboratory; Estados UnidosFil: Kassim, N. E.. Spece Sciences División. Naval Research Laboratory; Estados Unido

A Reverse Monte Carlo study of H+D Lyman alpha absorption from QSO spectra

A new method based on a Reverse Monte Carlo [RMC] technique and aimed at the inverse problem in the analysis of interstellar (intergalactic) absorption lines is presented. The line formation process in chaotic media with a finite correlation length $(l > 0)$ of the stochastic velocity field (mesoturbulence) is considered. This generalizes the standard assumption of completely uncorrelated bulk motions $(l \equiv 0)$ in the microturbulent approximation which is used for the data analysis up-to-now. It is shown that the RMC method allows to estimate from an observed spectrum the proper physical parameters of the absorbing gas and simultaneously an appropriate structure of the velocity field parallel to the line-of-sight. The application to the analysis of the H+D Ly$\alpha$ profile is demonstrated using Burles & Tytler [B&T] data for QSO 1009+2956 where the DI Ly$\alpha$ line is seen at $z_a = 2.504$. The results obtained favor a low D/H ratio in this absorption system, although our upper limit for the hydrogen isotopic ratio of about $4.5\times10^{-5}$ is slightly higher than that of B&T (D/H = $3.0^{+0.6}_{-0.5} \times 10^{-5}$). We also show that the D/H and N(HI) values are, in general, correlated, i.e. the derived D-abundance may be badly dependent on the assumed hydrogen column density. The corresponding confidence regions for an arbitrary and a fixed stochastic velocity field distribution are calculated.Comment: 6 pages, LaTeX, 2 Postscript figures, to appear in "The Primordial Nuclei and Their Galactic Evolution", eds. N. Prantzos, M. Tosi, R. von Steiger (Kluwer: Dordrecht

The Future of Academic MIS: Redux

As the quotes that preface this article indicate, predicting the future is tough. This article is about the future of the academic discipline called Management Information Systems, often referred to simply by the acronym MIS. Since the late 2000s, faculty who teach MIS and conduct research in this academic discipline have been concerned about issues like fluctuating enrollments, changing technologies, and concerns about the relevance of research in the discipline. This article begins by describing and examining the field of MIS in 2010, and then the analysis turns to a description of what the future looks like from the perspective of 2016. The next topic is the intellectual underpinnings of our field, with a focus on the broad research categories that have characterized MIS research in the past. This leads to a discussion of a series of research topics that are important today, to both academics and practitioners, and that will still be of great importance to both groups three to five to even 10 years in the future. The next section explores what is being published in top MIS journals currently, compared to which topics have been popular over the past few decades, and compared to the research topics identified as important now and in the future. The article ends with a few closing thoughts

Rendering real-time dashboards using a GraphQL-based UI Architecture

With the increase in the complexity of the systems being built and demand in the quality of service by the customers, developing and providing highly efficient real-time systems is one of the biggest challenges today for software enterprises. BluemixTM ─ IBM’s cloud offering implemented on Cloud Foundry, an open source “Platform as a Service” (PaaS), is an example of such a system. Currently, there are approx. 26 infrastructural services running in the background from where the data is fetched and is rendered on different dashboards of the system. However, the system suffers from performance issues. This thesis explores the performance improvements of the real-time dashboards by introducing our proposed GraphQL-based UI architecture which allows caching and asynchronous loading. The test results of this architecture’s implementation on the Bluemix Usage Dashboard show that the Real data renders 245% faster and the Switching Account 153% faster than the existing system

Gaucho Banking Redux

Argentina's economic crisis has strong similarities with previous crises stretching back to the nineteenth century. A common thread runs through all these crises: the interaction of a weak, undisciplined, or corruptible banking sector, and some other group of conspirators from the public or private sector that hasten its collapse. This pampean propensity for crony finance was dubbed gaucho banking' more than one hundred years ago. What happens when such a rotten structure interacts with a convertibility plan? We compare the 1929 and 2001 crises the two instances where rigid convertibility plans failed and reach two main conclusions. First, a seemingly robust currency-board can be devastated by an ill-conceived approach to the problems of internal and external convertibility (or, to rephrase Gresham, bad inside money drives out good outside money'). Second, when modern economic orthodoxy collides with caudillo-style institutional backwardness, a desperate regime with its hands tied in both monetary and fiscal domains will be sorely tempted by a capital levy' on the financial sector (for, as Willie Sutton said when asked why he robbed banks, because that's where the money is).

Gaucho banking redux

Argentina's economic crisis has strong similarities with previous crises stretching back to the nineteenth century. A common thread runs through all these crises: the interaction of a weak, undisciplined, or corruptible banking sector, and some other group of conspirators from the public or private sector that hasten its collapse. This pampean propensity for crony finance was dubbed "gaucho banking" more than one hundred years ago. What happens when such a rotten structure interacts with a convertibility plan? We compare the 1929 and 2001 crises-the two instances where rigid convertibility plans failed-and reach two main conclusions. First, a seemingly robust currency-board can be devastated by an ill-conceived approach to the problems of internal and external convertibility (or, to rephrase Gresham, "bad inside money drives out good outside money"). Second, when modern economic orthodoxy collides with caudillo-style institutional backwardness, a desperate regime with its hands tied in both monetary and fiscal domains will be sorely tempted by a "capital levy" on the financial sector (for, as Willie Sutton said when asked why he robbed banks, "because that's where the money is").Argentina