OH Maser sources in W49N: probing differential anisotropic scattering with Zeeman pairs

Our analysis of a VLBA 12-hour synthesis observations of the OH masers in W49N has provided detailed high angular-resolution images of the maser sources, at 1612, 1665 and 1667 MHz. The images, of several dozens of spots, reveal anisotropic scatter broadening; with typical sizes of a few tens of milli-arc-seconds and axial ratios between 1.5 to 3. The image position angles oriented perpendicular to the galactic plane are interpreted in terms of elongation of electron-density irregularities parallel to the galactic plane, due to a similarly aligned local magnetic field. However, we find the apparent angular sizes on the average a factor of 2.5 less than those reported by Desai et al., indicating significantly less scattering than inferred earlier. The average position angle of the scattered broadened images is also seen to deviate significantly (by about 10 degrees) from that implied by the magnetic field in the Galactic plane. More intriguingly, for a few Zeeman pairs in our set, we find significant differences in the scatter broadened images for the two hands of polarization, even when apparent velocity separation is less than 0.1 km/s. Here we present the details of our observations and analysis, and discuss the interesting implications of our results for the intervening anisotropic magneto-ionic medium, as well as a comparison with the expectations based on earlier work.Comment: 5 pages, 3 figures, submitted to the Proceedings of the IAU Symposium 287: "Cosmic masers - from OH to H0

Microscopic mass estimations

The quest to build a mass formula which have in it the most relevant microscopic contributions is analyzed. Inspired in the successful Duflo-Zuker mass description, the challenges to describe the shell closures in a more transparent but equally powerful formalism are discussed.Comment: 14 pages, 6 figures, submitted to Journal of Physics G, Focus issue on Open Problems in Nuclear Structure Theor

Linear conjugacy of chemical kinetic systems

Two networks are said to be linearly conjugate if the solution of their dynamic equations can be transformed into each other by a positive linear transformation. The study on dynamical equivalence in chemical kinetic systems was initiated by Craciun and Pantea in 2008 and eventually led to the Johnston-Siegel Criterion for linear conjugacy (JSC). Several studies have applied Mixed Integer Linear Programming (MILP) approach to generate linear conjugates of MAK (mass action kinetic) systems, Bio-CRNs (which is a subset of Hill-type kinetic systems when the network is restricted to digraphs), and PL-RDK (complex factorizable power law kinetic) systems. In this study, we present a general computational solution to construct linear conjugates of any "rate constant-interaction function decomposable" (RID) chemical kinetic systems, wherein each of its rate function is the product of a rate constant and an interaction function. We generate an extension of the JSC to the complex factorizable (CE) subset of RID kinetic systems and show that any non-complex factorizable (NE) RID kinetic system can be dynamically equivalent to a CF system via transformation. We show that linear conjugacy can be generated for any RID kinetic systems by applying the JSC to any NE kinetic system that are transformed to CF kinetic system

Molecules with a peptide link in protostellar shocks: a comprehensive study of L1157

Interstellar molecules with a peptide link -NH-C(=O)-, like formamide (NH$_2$CHO), acetamide (NH$_2$COCH$_3$) and isocyanic acid (HNCO) are particularly interesting for their potential role in pre-biotic chemistry. We have studied their emission in the protostellar shock regions L1157-B1 and L1157-B2, with the IRAM 30m telescope, as part of the ASAI Large Program. Analysis of the line profiles shows that the emission arises from the outflow cavities associated with B1 and B2. Molecular abundance of $\approx~(0.4-1.1)\times 10^{-8}$ and $(3.3-8.8)\times 10^{-8}$ are derived for formamide and isocyanic acid, respectively, from a simple rotational diagram analysis. Conversely, NH$_2$COCH$_3$ was not detected down to a relative abundance of a few $\leq 10^{-10}$. B1 and B2 appear to be among the richest Galactic sources of HNCO and NH$_2$CHO molecules. A tight linear correlation between their abundances is observed, suggesting that the two species are chemically related. Comparison with astrochemical models favours molecule formation on ice grain mantles, with NH$_2$CHO generated from hydrogenation of HNCO.Comment: 11 pages, 9 figures. Accepted for publication in MNRAS Main Journal. Accepted 2014 August 19, in original form 2014 July

[Re] Measuring [LEED] sustainability: from a global rating system to tropical specificity

This paper explores the applicability of the LEED certification system through the case study of Puerto Rico (P.R.), a United States (U.S.) Commonwealth island in the Caribbean, where LEED has become widely recognized as a standard because of the geopolitical relationship with the mainland. Although LEED is used internationally, it was initially developed by the U.S. Green Building Council as a tool to measure building performance in a modern American urban environment with temperate climate, a steady economy and easy access to technology. Furthermore, regionalization strategies such as Regional Priority Credits (RPCs) and Alternate Compliance Paths (ACPs), do not address the sociocultural reality of many regions. Therefore, the focus of this research is to analyse what indicators should be added, modified or substituted to develop a revised LEED model for the specific sociocultural context of P.R.? A mixed methods research will be used to compare LEED criteria with Sustainable Assessment Systems (SAS) such as the Building Research Establishment Environmental Assessment Method, the Living Building Challenge and SB Tool. Also, SAS in tropical countries such as Singapore (BCA Green Mark), Costa Rica (RESET) and India (TERI-GRIHA) will be examined. Case studies will be analysed with a main focus in Schools