Advanced media technologies have become an integral part of people's daily lives, providing them with new tools and environments for the formation and enactment of their identities. To date, the ...literature acknowledges that media technologies, such as social networking sites, are used to form and enact online identities, and that these platforms can simultaneously pose challenges to individuals' identity work. However, we know little about the precise online identity work strategies that individuals employ in response to the challenges they face over time.
This paper examines the online identity work dynamics of Instagram micro-influencers, for whom social network sites enable and guide them in forming and enacting their online identities on a daily basis. The study was guided by the following research question: what are the challenges that Instagram micro-influencers perceive online and what are the online identity work strategies that they employ in response to these challenges over time?
This study employs an extreme case approach to rigorously explore the lives of seven micro-influencers on Instagram. We combine in-depth data from narrative interviews, longitudinal data from online autobiographical narratives revealed through the participants' Instagram timelines, and follow-up interviews.
Our analysis revealed three main themes that highlight the challenges that Instagram micro-influencers face online: (1) amplified social expectations, (2) feelings of inauthenticity, and, as a result thereof, (3) psychological distress. We found that these challenges were viewed as catalysts for their online identity work processes. We identified three key online identity work strategies that the Instagram micro-influencers employed in response over time: (1) experimenting with their online identities, followed by either (2) segmenting between their online and offline identities, or (3) adding identities through online multiplicity.
Our research provides new insights into how individuals may respond to the challenge of managing their online identities over time by engaging in different online identity work strategies. This study highlights the importance of designing online media technologies that enable individuals to cope with online challenges. We emphasize the need to design online spaces for (1) the expression of authentic identities, (2) community building, and (3) online multiplicity.
The colliding-wind binary HD 168112 Blomme, R.; Rauw, G.; Volpi, D. ...
Astronomy and astrophysics (Berlin),
07/2024, Letnik:
687
Journal Article, Web Resource
Recenzirano
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Context. Radio surveys of early-type stars have revealed a number of non-thermal emitters. Most of these have been shown to be binaries, where the collision between the two stellar winds is ...responsible for the non-thermal emission. Aims. HD 168112 is a non-thermal radio emitter, whose binary nature has only recently been confirmed spectroscopically. We obtained independent spectroscopic observations to determine its orbit, in addition to radio observations to see if the thermal or non-thermal nature of the emission changes during the periastron passage. Methods. We monitored HD 168112 spectroscopically for a 13 yr time span. From these data, we determined the orbital parameters, which we compared to the previous results in the literature. The stellar parameters of both components were determined by comparing the spectra to TLUSTY models. From the spectral index of the radio observations, we found how the nature of the emission changes as the system goes through periastron. Combining our results with other literature data allowed us to further constrain the orbital and stellar parameters. Results. We find HD 168112 to have an orbital period of P = 512.17 −0.11 +0.41 days, an eccentricity of e = 0.7533 −0.0124 +0.0053 , and a mass ratio close to one. From our spectroscopic modelling, we derived the stellar parameters, but we had difficulty arriving at a spectroscopic mass ratio of one. The radio observations around periastron show only thermal emission, suggesting that most of the synchrotron photons are absorbed in the two stellar winds at that phase. Combining our data with the optical interferometry detection, we could constrain the inclination angle to i ~ 63°, and the mass of each component to ~26 M ⊙ . Conclusions. We have provided an independent spectroscopic confirmation of the binary nature of HD 168112. Although detected as a non-thermal radio emitter, near periastron the radio emission of this highly eccentric system is thermal and is mainly formed in the colliding-wind region. This effect will also occur in other colliding-wind binaries.
Context. The long-period O-star binary system HD 168112 and the triple O-star system HD 167971 are well-known sources of non-thermal radio emission that arises from a colliding wind interaction. The ...wind-wind collisions in these systems should result in phase-dependent X-ray emissions. The presence of a population of relativistic electrons in the wind interaction zone could affect the properties of the X-ray emission and make it deviate from the behaviour expected for adiabatic shocks. Aims. We investigate the X-ray emission of these systems with the goals of quantifying the fraction of the X-ray flux arising from wind interactions and determining whether these emissions follow the predictions for adiabatic wind-wind collisions. Methods. Six X-ray observations were collected with XMM-Newton. Three observations were scheduled around the most recent peri-astron passage of HD 168112. Spectra and light curves were analysed and compared with simple predictions of model calculations for X-ray emission from colliding wind systems. Results. The X-ray emission of HD 168112 varies as the inverse of the orbital separation, as expected for an adiabatic wind interaction zone. The relative contribution of intrinsic X-ray emission from wind-embedded shocks varies between 38% at periastron to 81% at apastron. The wind-wind collision zone remains adiabatic even around periastron passage. The X-ray emission of HD 167971 displays variations on the orbital timescale of the inner eclipsing binary. The existing data of this system do not allow us to probe variations on the timescale of the outer orbit. Conclusions. Shock modification due to the action of relativistic electrons does not seem to be efficiently operating in the HD 168112 system. In the existing observations, a significant part of the emission of HD 167971 must arise in the inner eclipsing binary. The origin of this emission is as yet unclear.
The subject of this study is the psychological contract approach to the employment relationship within the hospitality industry with special reference to highly educated employees. The purpose was to ...research the differences in the psychological contract and its relation to the intention to leave between highly-educated male and female employees. The research study conducted among this specific group worldwide provided a corpus of 247 respondents. The results show that psychological contract measures, and in particular job content, can explain why there is a substantial amount of variance among highly-educated employees regarding their intention to leave an organization, especially if the mediating role of affective commitment is taken into account. Moreover, it would appear that for women in particular, promotion opportunities and work-family balance were related to turnover intentions while for men the clarity of the job description was an important predictor for leaving. We suggest that the results of this study should be considered when developing gender-specific HRM policies to retain highly-educated staff. Considering the limitations of this study, we suggest that it be followed by research studies which concentrate on the job aspects which may be related to employee turnover. A longitudinal study concentrating on the relation between the psychological contract, turnover intentions and actual turnover behaviour should also be carried out.
We model the detailed time-evolution of discrete absorption components (DACs) observed in P Cygni profiles of the Si iv lambda1400 resonance doublet lines of the fast-rotating supergiant HD 64760 ...(B0.5 Ib). We adopt the common assumption that the DACs are caused by corotating interaction regions (CIRs) in the stellar wind. We perform 3D radiative transfer calculations with hydrodynamic models of the stellar wind that incorporate these large-scale density- and velocity-structures. We develop the 3D transfer code Wind3D to investigate the physical properties of CIRs with detailed fits to the DAC shape and morphology. We constrain the properties of large-scale wind structures with detailed fits to DACs observed in HD 64760. A model with two spots of unequal brightness and size on opposite sides of the equator-image and image brighter than the stellar surface and with opening angles of image and image diameter, respectively-provides the best fit to the observed DACs. The recurrence time of the DACs compared to the estimated rotational period corresponds to spot velocities that are 5 times slower than the rotational velocity. The mass-loss rate of the structured-wind model for HD 64760 does not exceed the rate of the spherically symmetric smooth-wind model by more than image. The fact that DACs are observed in a large number of hot stars constrains the clumping that can be present in their winds, as substantial amounts of clumping would tend to destroy the CIRs.
Building on social-exchange and self-determination theory, this study aimed to contribute to the scholarly literature on leadership and knowledge sharing by simultaneously testing how shared and ...transformational leadership and their interrelatedness may foster employees' perceptions of knowledge sharing behaviour among peers. Additionally, we investigated the mediating role of employees' basic psychological needs satisfaction (in terms of autonomy, competence and relatedness, respectively) as an additional explanatory mechanism to reveal how shared and transformational leadership may foster individuals' perceptions of knowledge sharing behaviour among peers. We employed PLS structural equation modelling to analyse survey data obtained from professionals in an R&D unit of a knowledge-intensive firm. We found shared leadership to be the most important factor enhancing employees' perceptions of knowledge sharing among peers, both directly and indirectly through employees' satisfaction of the need for autonomy. Transformational leadership was found to foster employees' knowledge sharing ultimately, through shared leadership and the need for autonomy satisfaction. We concluded that shared forms of leadership supplemented with transformational leadership on the part of formal leaders are important in contemporary work environments as they can foster employees' perceptions of knowledge sharing among peers and contribute towards employees' self-determination, which ultimately enhances perceptions of knowledge sharing among peers.
Modern astrometric and spectroscopic surveys have revealed a wealth of structure in the phase space of stars in the Milky Way, with evidence of resonance features and non-equilibrium processes. Using ...the third
Gaia
data release, we present evidence of a new resonance-like feature in the outer disc of the Milky Way. The feature is most evident in the angular momentum distribution of the young classical Cepheids, a population for which we can derive accurate distances over much of the Galactic disc. We then searched for similar features in the outer disc using a much larger sample of red giant stars, as well as a compiled list of over 31 million stars with spectroscopic line-of-sight velocity measurements. While much less evident in these two older samples, the distribution of stars in action-configuration space suggests that resonance features are present here as well. The position of the feature in action-configuration space suggests that the new feature may be related to the Galactic bar, but other possibilities are discussed.
Context. The Gaia-ESO Survey (GES) is a large spectroscopic survey that provides a unique opportunity to study the distribution of spectroscopic multiple systems among different populations of the ...Galaxy. Aims. Our aim is to detect binarity/multiplicity for stars targeted by the GES from the analysis of the cross-correlation functions (CCFs) of the GES spectra with spectral templates. Methods. We developed a method based on the computation of the CCF successive derivatives to detect multiple peaks and determine their radial velocities, even when the peaks are strongly blended. The parameters of the detection of extrema (doe) code have been optimized for each GES GIRAFFE and UVES setup to maximize detection. The doe code therefore allows to automatically detect multiple line spectroscopic binaries (SBn, n ≥ 2). Results. We apply this method on the fourth GES internal data release and detect 354 SBn candidates (342 SB2, 11 SB3, and even one SB4), including only nine SBs known in the literature. This implies that about 98% of these SBn candidates are new because of their faint visual magnitude that can reach V = 19. Visual inspection of the SBn candidate spectra reveals that the most probable candidates have indeed a composite spectrum. Among the SB2 candidates, an orbital solution could be computed for two previously unknown binaries: CNAME 06404608+0949173 (known as V642 Mon) in NGC 2264 and CNAME 19013257-0027338 in Berkeley 81 (Be 81). A detailed analysis of the unique SB4 (four peaks in the CCF) reveals that CNAME 08414659-5303449 (HD 74438) in the open cluster IC 2391 is a physically bound stellar quadruple system. The SB candidates belonging to stellar clusters are reviewed in detail to discard false detections. We suggest that atmospheric parameters should not be used for these system components; SB-specific pipelines should be used instead. Conclusions. Our implementation of an automatic detection of spectroscopic binaries within the GES has allowed the efficient discovery of many new multiple systems. With the detection of the SB1 candidates that will be the subject of a forthcoming paper, the study of the statistical and physical properties of the spectroscopic multiple systems will soon be possible for the entire GES sample.
We present e-MERLIN 21 cm (L-band) observations of single luminous OB stars in the Cygnus OB2 association, from the Cyg OB2 Radio Survey Legacy programme. The radio observations potentially offer the ...most straightforward, least model-dependent, determinations of mass-loss rates, and can be used to help resolve current discrepancies in mass-loss rates via clumped and structured hot star winds. We report here that the 21 cm flux densities of O3 to O6 supergiant and giant stars are less than ∼70 μJy. These fluxes may be translated to ‘smooth’ wind mass-loss upper limits of ∼4.4–4.8 × 10−6 M⊙ yr −1 for O3 supergiants and ≲2.9 × 10−6 M⊙ yr −1 for B0 to B1 supergiants. The first ever resolved 21 cm detections of the hypergiant (and luminous blue variable candidate) Cyg OB2 #12 are discussed; for multiple observations separated by 14 d, we detect an ∼69 per cent increase in its flux density. Our constraints on the upper limits for the mass-loss rates of evolved OB stars in Cyg OB2 support the model that the inner wind region close to the stellar surface (where Hα forms) is more clumped than the very extended geometric region sampled by our radio observations.
Context. The colliding winds in a massive binary system generate synchrotron emission due to a fraction of electrons that have been accelerated to relativistic speeds around the shocks in the ...colliding-wind region (CWR). Aims. We studied the radio light curve of 9 Sgr = HD 164794, a massive O-type binary with a 9.1-year period. We Investigated whether the radio emission varies consistently with orbital phase and we determined some parameters of the colliding-wind region (CWR). Methods. We reduced a large set of archive data from the Very Large Array (VLA) to determine the radio light curve of 9 Sgr at 2, 3.6, 6, and 20 cm. We also constructed a simple model that solves the radiative transfer in the CWR and both stellar winds. Results. The 2 cm radio flux shows clear phase-locked variability with the orbit. The behaviour at other wavelengths is less clear, mainly because of a lack of observations centred on 9 Sgr around periastron passage. The high fluxes and nearly flat spectral shape of the radio emission show that synchrotron radiation dominates the radio light curve at all orbital phases. The model provides a good fit to the 2 cm observations, allowing us to estimate that the brightness temperature of the synchrotron radiation emitted in the colliding-wind region at 2 cm Is at least 4 x 10 super(8) K. Conclusions. The simple model used here already allows us to derive important information about the CWR. We propose that 9 Sgr is a good candidate for more detailed modelling, as the CWR remains adiabatic during the whole orbit thus simplifying the hydrodynamics.
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