The magnetic field of the evolved star W43A

The majority of the observed planetary nebulae exhibit elliptical or bipolar structures. Theoretical modeling has indicated that magnetically collimated jets may be responsible for the formation of the non-spherical planetary nebulae. The aim of this project is to measure the Zeeman splitting caused by the magnetic field in the OH and H2O maser regions occurring in the circumstellar envelope and bipolar outflow of the evolved star W43A. We report a measured magnetic field of approximately 100 micro-gauss in the OH maser region of the circumstellar envelope around W43A. The GBT observations reveal a magnetic field strength B|| of ~30 mG changing sign across the H2O masers at the tip of the red-shifted lobe of the bipolar outflow. We also find that the OH maser shell shows no sign of non-spherical expansion and that it probably has an expansion velocity that is typical for the shells of regular OH/IR stars. The GBT observations confirm that the magnetic field collimates the H2O maser jet, while the OH maser observations show that a strong large scale magnetic field is present in the envelope surrounding the W43A central star. The magnetic field in the OH maser envelope is consistent with the one extrapolated from the H2O measurements, confirming that magnetic fields play an important role in the entire circumstellar environment of W43A.Comment: 6 pages, 5 figure

Double Relaxation via AdS/CFT

We exploit the AdS/CFT correspondence to investigate thermalization in an N=2 strongly coupled gauge theory including massless fundamental matter (quark). More precisely, we consider the response of a zero temperature state of the gauge theory under variation of an external electric field leading to a time-dependent current. The holographic dual of the above set-up is given by introducing a time-dependent electric field on the probe D7-brane embedded in an AdS_5 X S^5 background. In the dual gravity theory, due to a time-dependent electric field an apparent horizon forms on the brane which, according to AdS/CFT dictionary, is the counterpart of the thermalization process in the gauge theory. We classify different functions for time-dependent electric field and study their effect on the apparent horizon formation. In the case of pulse functions where the electric field varies from zero to zero, apart from non-equilibrium phase, we observe that two apparent horizons form on the brane. On the gauge theory side, it means that the state of the gauge theory experiences two different temperatures during the time evolution.Comment: 28 pages, 13 figures, published versio

From the ashes: JVLA observations of water fountain nebula candidates show the rebirth of IRAS 18455+0448

[abridged] The class of water fountain nebulae is thought to represent the stage of the earliest onset of collimated bipolar outflows during the post-Asymptotic Giant Branch phase. They thus play a crucial role in the study of the formation of bipolar Planetary Nebulae (PNe). To date, 14 water fountain nebulae have been identified. The identification of more sources in this unique stage of stellar evolution will enable us to study the origin of bipolar PNe morphologies in more detail. We present the results of seven sources observed with the JVLA that were identified as water fountain candidates in an Effelsberg 100m telescope survey of 74 AGB and early post-AGB stars. We find that our sample of water fountain candidates displays strong variability in their 22 GHz H2O maser spectra. The JVLA observations show an extended bipolar H2O maser outflow for one source, the OH/IR star IRAS 18455+0448. This source was previously classified as a 'dying' OH/IR star based on the exponential decrease of its 1612 MHz OH maser and the lack of H2O masers. We therefore also re-observed the 1612, 1665, and 1667 MHz OH masers. We confirm that the 1612 MHz masers have not reappeared and find that the 1665/1667 MHz masers have decreased in strength by several orders of magnitude during the last decade. The OH/IR star IRAS 18455+0448 is confirmed to be a new addition to the class of water fountain nebulae. Its kinematic age is approximately 70 yr, but could be lower, depending on the distance and inclination. Previous observations indicate, with significant uncertainty, that IRAS 18455+0448 has a surprisingly low mass compared to available estimates for other water fountain nebulae. The available historical OH maser observations make IRAS 18455+0448 unique for the study of water fountain nebulae and the launch of post-AGB bipolar outflows...Comment: 8 pages, 5 figures, accepted for publication in A&A (revised minor typos

Magnetic fields around evolved stars: further observations of H2_2O maser polarization

We aim to detect the magnetic field and infer its properties around four AGB stars using H$_2$O maser observations. The sample we observed consists of the following sources: the semi-regular variable RT Vir and the Mira variables AP Lyn, IK Tau, and IRC+60370. We observed the 6$_{1,6}-5_{2,3}$ H$_2$O maser rotational transition, in full-polarization mode, to determine its linear and circular polarization. Based on the Zeeman effect, one can infer the properties of the magnetic field from the maser polarization analysis. We detected a total of 238 maser features, in three of the four observed sources. No masers were found toward AP Lyn. The observed masers are all located between 2.4 and 53.0 AU from the stars. Linear and circular polarization was found in 18 and 11 maser features, respectively. We more than doubled the number of AGB stars in which magnetic field has been detected from H$_2$O maser polarization, as our results confirm the presence of fields around IK Tau, RT Vir and IRC+60370. The strength of the field along the line of sight is found to be between 47 and 331 mG in the H$_2$O maser region. Extrapolating this result to the surface of the stars, assuming a toroidal field ($\propto$ r$^{-1}$), we find magnetic fields of 0.3-6.9 G on the stellar surfaces. If, instead of a toroidal field, we assume a poloidal field ($\propto$ r$^{-2}$), then the extrapolated magnetic field strength on the stellar surfaces are in the range between 2.2 and $\sim$115 G. Finally, if a dipole field ($\propto$ r$^{-3}$) is assumed, the field strength on the surface of the star is found to be between 15.8 and $\sim$1945 G. The magnetic energy of our sources is higher than the thermal and kinetic energy in the H$_2$O maser region of this class of objects. This leads us to conclude that, indeed, magnetic fields probably play an important role in shaping the outflows of evolved stars. (abridged)Comment: 15 pages, 5 figures, 7 tables. Accepted for publication in A&

Venturi nozzles for desalination brine discharges

Seawater desalination is a reliable way to confront the growing challenges of freshwater demands in the world. Brine is the primary by-product of this process and needs to be carefully managed and discharged back into the sea. In coastal desalination plants, the use of submerged outfall as a pipeline laying on the ocean floor is a popular strategy to minimize the environmental impacts of brine discharge. The Venturi nozzle has been proposed as a more efficient method for dispersing brine into the ocean. However, it requires a high exit velocity, which poses limitations for steep nozzle angles in shallow waters. This study aims to investigate the benefits of a lower range of exit velocities in the Venturi nozzles. The 60◦ inclined dense jet from a Venturi nozzle was explored, numerically and experimentally, and the results were compared to those of a simple dense jet. Comparisons showed that the Venturi nozzle decreases the flow path and diminishes flow dilution at the critical points. However, this reduction can be compensated by increasing the discharge Froude number to reach the same trajectory as a simple jet. It is important to note that this compensation is intricately linked to the discharge velocity, and it makes the use of Venturi nozzles for brine discharge a challenging proposition in both deep and shallow waters

Improving employees' performance through internal marketing and organizational learning: mediating role of organizational innovation in an emerging market

This study identifies a specific relationship between internal marketing and organizational learning as the key drivers of organizational innovation, which build employees performance in the context of the petroleum industry. A model of the antecedents of organizational innovation was examined in a survey conducted among managers and employed specialists working in the oil industry in Iran. Structural equation modelling via Smart PLS was employed to gain insight into the various influences and relationships. We empirically scrutinized relationships between these constructs by validating a conceptual model employing SEM. The results indicate that internal marketing and organizational learning are key drivers of organizational innovation, which they are build employees performance. As well as, the results clarify that it is possible to improve the level of employee performance even through the complementary partial mediating role of organizational innovation. Additionally, this study makes a managerial contribution to the understanding of internal marketing, organizational learning and innovation on employee performance

Information technology directors' efforts on innovation, integrated marketing communications and brand equity

Purpose – The main purpose of this study is to examine information directors in the area of communication activities related to innovation and marketing decisions in branding. Design/methodology/approach – The study is quantitative and utilized structural equation modeling technique with the approach of minimum trivial squares for analyzing the data. 130 questionnaires were distributed among information technology directors in Tehran and they form the statistical population for the research. Findings – The results suggested that innovation in integrated marketing communications has positively significant effect. In addition, both the variables of innovation and integrated marketing communications positively and significantly affect the three components of brand equity (namely, brand image, the perceived quality and brand loyalty). Originality/value – Despite the growing acknowledgment the importance of innovation, integrated marketing communications and brand equity, however, there are few studies on the role and importance of information technology directors’ efforts on innovation, integrated marketing communications and brand equity

Why leadership style matters: a closer look at transformational leadership and internal marketing

Purpose – The main purpose of this study is to evaluate the relationship between transformational leadership and internal marketing which is underscored by the centrality of human resources in satisfying employee’s needs and how internal marketing, as a moderator and mediator, can facilitate the effects of transformational leadership on social capital and employee loyalty. Design/methodology/approach – This study develops a model and a number of propositions, based on preceding literature on transformational leadership and internal marketing on social capital and employee loyalty Findings – The model proposes that transformational leadership can play a vital role in codification of human resources variables such as internal marketing, which is founded upon the principle of paying greater attention to employees. Moreover, despite the research gap on the relationship between social capital and employee loyalty, it can be concluded that social capital can increase the level of employee loyalty to organization. Research limitations/implications – The proposed model has a number of academic and managerial contributions. This study contributes the knowledge by examining the relationship between transformational leadership and internal marketing. Managerially, this study helps managers to emphasize the centrality of human resources in satisfying employees and increase their loyalty towards the company. In addition, guarantees management effectiveness and organizational success in reaching their intended goals. Originality/value – Despite the growing acknowledgment the importance of transformational leadership as a process in which leaders and followers upgrade each other’s level of ethic and motivation. However, there are few studies on the role and importance of transformational leadership on developing and reinforcing the internal marketing