ALMA observations of the vibrationally-excited rotational CO transition v=1,J=3−2v=1, J=3-2 towards five AGB stars

We report the serendipitous detection with ALMA of the vibrationally-excited pure-rotational CO transition $v=1, J=3-2$ towards five asymptotic giant branch (AGB) stars, $o$ Cet, R Aqr, R Scl, W Aql, and $\pi^1$ Gru. The observed lines are formed in the poorly-understood region located between the stellar surface and the region where the wind starts, the so-called warm molecular layer. We successfully reproduce the observed lines profiles using a simple model. We constrain the extents, densities, and kinematics of the region where the lines are produced. R Aqr and R Scl show inverse P-Cygni line profiles which indicate infall of material onto the stars. The line profiles of $o$ Cet and R Scl show variability. The serendipitous detection towards these five sources shows that vibrationally-excited rotational lines can be observed towards a large number of nearby AGB stars using ALMA. This opens a new possibility for the study of the innermost regions of AGB circumstellar envelopes.Comment: 6 pages, 2 figures, 2 tables, 2016MNRAS.463L..74

CO and HCN isotopologue ratios in the outflows of AGB stars

Isotopologue line intensity ratios of circumstellar molecules have been widely used to trace the photospheric elemental isotopic ratios of evolved stars. However, depending on the molecular species and the physical conditions of the environment, the circumstellar isotopologue ratio may deviate considerably from the stellar atmospheric value. In this paper, we aim to examine how the CO and HCN abundance ratios vary radially due to chemical reactions in the outflows of AGB stars and the effect of excitation and optical depth on the resulting line intensity ratios. We find that the circumstellar 12CO/13CO can deviate from its atmospheric value by up to 25-94% and 6-60% for C- and O-type CSEs, respectively. We show that variations of the intensity of the ISRF and the gas kinetic temperature can significantly influence the CO isotopologue ratio in the outer CSEs. On the contrary, the H12CN/H13CN ratio is stable for all tested mass-loss rates. The RT modeling shows that the integrated line intensity ratio of CO of different rotational transitions varies significantly for stars with intermediate mass-loss rates due to combined chemical and excitation effects. In contrast, the excitation conditions for the both HCN isotopologues are the same. We demonstrate the importance of using the isotopologue abundance profiles from chemical models as inputs to RT models in the interpretation of isotopologue observations. Previous studies of CO isotopologue ratios are based on multi-transition data for individual sources and it is difficult to estimate the errors in the reported values due to assumptions that are not entirely correct according to this study. If anything, previous studies may have overestimated the circumstellar 12CO/13CO abundance ratio. The use of the HCN as a tracer of C isotope ratios is affected by fewer complicating problems, provided one accounts corrections for high optical depths.Comment: 14 pages, 11 figure

Linear magnetoresistance in a quasi-free two dimensional electron gas in an ultra-high mobility GaAs quantum well

We report a magnetotransport study of an ultra-high mobility ($\bar{\mu}\approx 25\times 10^6$\,cm$^2$\,V$^{-1}$\,s$^{-1}$) $n$-type GaAs quantum well up to 33 T. A strong linear magnetoresistance (LMR) of the order of 10$^5$ % is observed in a wide temperature range between 0.3 K and 60 K. The simplicity of our material system with a single sub-band occupation and free electron dispersion rules out most complicated mechanisms that could give rise to the observed LMR. At low temperature, quantum oscillations are superimposed onto the LMR. Both, the featureless LMR at high $T$ and the quantum oscillations at low $T$ follow the empirical resistance rule which states that the longitudinal conductance is directly related to the derivative of the transversal (Hall) conductance multiplied by the magnetic field and a constant factor $\alpha$ that remains unchanged over the entire temperature range. Only at low temperatures, small deviations from this resistance rule are observed beyond $\nu=1$ that likely originate from a different transport mechanism for the composite fermions

Influence of additives on decrease of temperature of slag flow from energy coal in wet bottom boiler

This paper describes the features of the energy coal combusted in a power plant, its impact on energy production, while the possibility of using natural and secondary raw materials to modify the properties of energy coal. All selected types of additives (fluorspar, de-metallized steelmaking slag (DSS), dolomite, and limestone) in admixture of coal have clearly proved their ability to reduce the pour point of the ash in the laboratory experiments. The highest decrease of the temperature at 5 % of the additive was achieved by fluorspar and dolomite from the temperature of 1 593 °C to the temperature of 1 307 °C. In terms of the economy and the availability of the additives the most suitable seems to be DSS

Strategic and large scale government IT projects management: innovation report

This research focuses on the Implementation of IT systems and public sector and national ID card projects in particular. Such projects have high expectations but low success rates. The study Investigated the factors contributing to IT projects failure through on extensive review of the existing literature. This was enriched and tested by close Involvement with the UAE national ID card project, surveys and In depth interviews with senior managers from other ID card projects and presentations and attendance at over 50 conferences on this subject. Many of the factors leading to either success or failure identified in many practical studies could be addressed through a well designed project management methodology. Based on the literature, practical experience, observations and feedback from practitioners a project management methodology; named PROMOTE - PROject Management Of Technology Endeavours - was developed and tested for the planning and Implementing large scale IT projects mainly In a government context. The US$200+ million dollar national ID programme In the United Arab Emirates was the main test vehicle. Its Innovations include a hybrid systems development/project management customer based philosophy, a number of new tools and techniques and the Introduction of a mentor for the project manager. To help assess the general applicability of the methodology it was also tested In the Saudi Arabia, Oman, and Bahrain national ID initiatives. The methodology phases were refined several times (and other phases were added) to address the problems Identified from UAE project, the literature, the experiences reported at GCC committee meetings and from other large scale Implementations around the world (from conferences and study visits to other countries). From the testing conducted, the methodology is believed to add a significant contribution to the field of IT projects Implementation and In Increasing the success chances of such projects. Such success should have a profound Impact on government services. The study also recognises that a better understanding of the new methodology and its contributions Is only possible through further research and application In other large scale IT projects. This should allow the extension of the applicability of this methodology to a much wider spectrum

Metallurgical brownfields re-use in the conditions of Slovakia – a case study

The article deals with a system approach to solving the problems of re-use of metallurgical brownfields in Slovakia, as a potential tool to support further regional development, accepting the valid legal regulations of the Slovak Republic, as well as the principles of sustainable environmental development. The solution to this problem was based on the identification of the specific aspects of the benefits and risks of internal and external environment determining the resulting benefit from the realisation of potential metallurgical brownfields development projects and monitoring of selected indicators supporting the development of the region itself

Anisotropic and strong negative magneto-resistance in the three-dimensional topological insulator Bi2Se3

We report on high-field angle-dependent magneto-transport measurements on epitaxial thin films of Bi2Se3, a three-dimensional topological insulator. At low temperature, we observe quantum oscillations that demonstrate the simultaneous presence of bulk and surface carriers. The magneto- resistance of Bi2Se3 is found to be highly anisotropic. In the presence of a parallel electric and magnetic field, we observe a strong negative longitudinal magneto-resistance that has been consid- ered as a smoking-gun for the presence of chiral fermions in a certain class of semi-metals due to the so-called axial anomaly. Its observation in a three-dimensional topological insulator implies that the axial anomaly may be in fact a far more generic phenomenon than originally thought.Comment: 6 pages, 4 figure

Modelling of copper and zinc adsorption onto zeolite

Adsorption of Cu(II) and Zn(II) ions from metallurgical solutions has been studied and the adsorption capacity of zeolite (Nižný Hrabovec, SK) has been determined. Zeolites are characterized by relatively high sorption capacity, i.e. Cu(II) and Zn(II) can be removed even at relatively low concentrations. The experiments were realised in a batch system and evaluated using isotherms. According to the results of the experiments the adsorption equilibrium of Cu(II) and Zn(II) on zeolite was best described by Freundlich isotherm. The maximum sorption capacity was 1,48 and 1,49 mg/g for Cu(II) and Zn(II), respectively. The experimental results of this study demonstrate that zeolite is suitable for adsorption of copper and zinc from aqueous solutions at low concentrations