Merging Phase Research Articles

Spiraling work engagement and change appraisals: A three-wave longitudinal study during organizational change.

In this longitudinal field study, we examine reciprocal relationships between within-person changes in work engagement and cognitive appraisals of change (threat and challenge) across an organizational merger. Examination of these cyclical relationships provides a more accurate understanding of the complexity of employees' experience of change and a new test of spiraling work engagement and cognitive appraisals. Latent change score modeling is used to analyze 3 waves of longitudinal survey data (N = 623). Our findings showed that engagement mitigated threat appraisals and enhanced challenge appraisals through pre- and postmerger phases. A reciprocal relationship between threat appraisal and engagement was also observed, such that threat fueled decreases in engagement throughout the merger. Challenge appraisal was associated with enhanced work engagement during the first merger phase. This examination advocates managers of change to foster employees' work engagement already prior to change endeavors, along with mitigating threat appraisals throughout organizational change events. Fostering positive challenge appraisals appears to be particularly important for employees' work engagement during times of major changes. Findings suggest that upward spiral of work engagement, as postulated on the basis of the broaden-and-build theory, may be more likely to occur through engagement mitigating negative cognitions (threat) than promoting positive cognitions (challenge). (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Empirical relations for gravitational-wave asteroseismology of binary neutron star mergers

We construct new, multivariate empirical relations for measuring neutron star radii and tidal deformabilities from the dominant gravitational wave frequency in the post-merger phase of binary neutron star mergers. The relations determine neutron star radii and tidal deformabilities for specific neutron star masses with consistent accuracy and depend only on two observables: the post-merger peak frequency $f_{\rm peak}$ and the chirp mass $M_{\rm chirp}$. The former could be measured with good accuracy from gravitational waves emitted in the post-merger phase using next-generation detectors, whereas the latter is already obtained with good accuracy from the inspiral phase with present-day detectors. Our main data set consists of a gravitational wave catalogue obtained with CFC/SPH simulations. We also extract the $f_{\rm peak}$ frequency from the publicly available CoRe data set, obtained through grid-based GRHD simulations and find good agreement between the extracted frequencies of the two data sets. As a result, we can construct empirical relations for the combined data sets. Furthermore, we investigate empirical relations for two secondary peaks, $f_{2-0}$ and $f_{\rm spiral}$, and show that these relations are distinct in the whole parameter space, in agreement with a previously introduced spectral classification scheme. Finally, we show that the spectral classification scheme can be reproduced using machine-learning techniques.

Quantum enhanced kHz gravitational wave detector with internal squeezing

We propose adding a nonlinear element to a long signal recycling cavity to enhance the high-frequency sensitivity (900 Hz–5 kHz) of a kilometer-scale interferometric gravitational wave detector. Using numbers for absorption and scattering losses in the detector consistent with advanced LIGO+, we demonstrate a factor of 3.5 improvement in quantum noise limited strain sensitivity in the kHz regime. Such a configuration is robust to internal losses and reduces the requirement on the amount of circulating power in the detector to achieve sensitivity comparable to future gravitational wave detectors. This proposed configuration is compatible with the existing gravitational wave detector vacuum infrastructure and could enable exploration of exotic science, such as observing the merger phase of binary neutron stars, which in turn may provide constraints on the neutron star equation of state.

The GRIFFIN Project—Formation of Star Clusters with Individual Massive Stars in a Simulated Dwarf Galaxy Starburst

Abstract We describe a population of young star clusters (SCs) formed in a hydrodynamical simulation of a gas-rich dwarf galaxy merger resolved with individual massive stars at subparsec spatial resolution. The simulation is part of the griffin (Galaxy Realizations Including Feedback From INdividual massive stars) project. The star formation environment during the simulation spans seven orders of magnitude in gas surface density and thermal pressure, and the global star formation rate surface density (ΣSFR) varies by more than three orders of magnitude during the simulation. Young SCs more massive than form along a mass function with a power-law index α ∼ −1.7 (α ∼ −2 for ) at all merger phases, while the normalization and the highest SC masses (up to ∼106 M ⊙) correlate with ΣSFR. The cluster formation efficiency varies from Γ ∼ 20% in early merger phases to Γ ∼ 80% at the peak of the starburst and is compared to observations and model predictions. The massive SCs (≳104 M ⊙) have sizes and mean surface densities similar to observed young massive SCs. Simulated lower mass clusters appear slightly more concentrated than observed. All SCs form on timescales of a few Myr and lose their gas rapidly resulting in typical stellar age spreads between σ ∼ 0.1–2 Myr (1σ), consistent with observations. The age spreads increase with cluster mass, with the most massive cluster (∼106 M ⊙) reaching a spread of 5 Myr once its hierarchical formation finishes. Our study shows that it is now feasible to investigate the SC population of entire galaxies with novel high-resolution numerical simulations.

Comparative study of deep learning models for optical coherence tomography angiography.

Optical coherence tomography angiography (OCTA) is a promising imaging modality for microvasculature studies. Meanwhile, deep learning has achieved rapid development in image-to-image translation tasks. Some studies have proposed applying deep learning models to OCTA reconstruction and have obtained preliminary results. However, current studies are mostly limited to a few specific deep neural networks. In this paper, we conducted a comparative study to investigate OCTA reconstruction using deep learning models. Four representative network architectures including single-path models, U-shaped models, generative adversarial network (GAN)-based models and multi-path models were investigated on a dataset of OCTA images acquired from rat brains. Three potential solutions were also investigated to study the feasibility of improving performance. The results showed that U-shaped models and multi-path models are two suitable architectures for OCTA reconstruction. Furthermore, merging phase information should be the potential improving direction in further research.

Inferring prompt black-hole formation in neutron star mergers from gravitational-wave data

The gravitational-wave GW170817 is associated to the inspiral phase of a binary neutron star coalescence event. The LIGO-Virgo detectors sensitivity at high frequencies was not sufficient to detect the signal corresponding to the merger and post-merger phases. Hence, the question whether the merger outcome was a prompt black hole formation or not must be answered using either the pre-merger gravitational wave signal or electromagnetic counterparts. In this work we present two methods to infer the probability of prompt black hole formation, using the analysis of the inspiral gravitational-wave signal. Both methods combine the posterior distribution from the gravitational-wave data analysis with numerical relativity results. One method relies on the use of phenomenological models for the equation of state and on the estimate of the collapse threshold mass. The other is based on the estimate of the tidal polarizability parameter $\tilde{\Lambda}$ that is correlated in an equation-of-state agnostic way with the prompt BH formation. We analyze GW170817 data and find that the two methods consistently predict a probability of ~ 50-70% for prompt black-hole formation, which however may significantly decrease below 10% if the maximum mass constraint from PSR J0348+0432 or PSR J0740+6620 is imposed.

Talent management and the HR function in cross-cultural mergers and acquisitions: The role and impact of bi-cultural identity

This paper examines bi-cultural talent in relation to human resource management (HRM) practices in cross-cultural merger and acquisitions (M&A). The intersection of HRM, bi-cultural talent management and cross-cultural M&A literature proposes a conceptual framework to capture the complexity of bi-cultural talent management and reveals the dominant macro-characterization of the extant HRM literature focussing on a more micro-orientated perspective. The paper develops a matrix by underlining spatial dimensions (spanning micro-aspects of the individual employee through to the macro-entity of firm and its location in the macro-national cultural context) and temporal dimensions (consisting of pre-merger, during merger and post-merger phases). This provides a template which examines the multi-level dynamics of bi-cultural talent management. The argument identifies ways in which extant cross-cultural lenses require deeper understanding of bi-cultural talent management in M&A settings. Future research directions and agendas are identified.

Coordinated lane change in autonomous driving: a computationally aware solution

Abstract This paper addresses the design of coordinated maneuvers in an autonomous driving set-up involving multiple vehicles. In particular, we consider a lane change problem where a vehicle has to merge in a platoon traveling in the adjacent lane of a two-lane one way road. We propose a cooperative solution that trades optimality for computational feasibility without simplifying the merging vehicle dynamics. The key idea is decoupling the problem into two phases: an online coordination phase where vehicles in the platoon create a gap where the merging vehicle can safely enter, and a merging phase, where the merging vehicle change lane by tracking a pre-computed optimal maneuver. A numerical case study shows the achieved trade off between performance degradation and reduction in computing time of the proposed solution.

Quasi-normal modes of static spherically symmetric black holes in f(R) theory

We study the quasi-normal modes (QNMs) of static, spherically symmetric black holes in f(R) theories. We show how these modes in theories with non-trivial f(R) are fundamentally different from those in general relativity. In the special case of f(R) = alpha R^2 theories, it has been recently argued that iso-spectrality between scalar and vector modes breaks down. Here, we show that such a break down is quite general across all f(R) theories, as long as they satisfy f''(0)/(1+f''(0)) ne 0, where a prime denotes derivative of the function with respect to its argument. We specifically discuss the origin of the breaking of isospectrality. We also show that along with this breaking the QNMs receive a correction that arises when f''(0)/(1+f'(0)) ne 0 owing to the inhomogeneous term that it introduces in the mode equation. We discuss how these differences affect the “ringdown” phase of binary black hole mergers and the possibility of constraining f(R) models with gravitational-wave observations. We also find that even though the iso-spectrality is broken in f(R) theories, in general, nevertheless in the corresponding scalar-tensor theories in the Einstein frame it is unbroken.

A novel approach for merging ontologies using formal concept analysis

Ontologies are mainly used for knowledge sharing and also as a knowledge structure. Due to the rising nature of ontologies, the method of merging information in the corporate realm turns to be critical. In the existing methods, formal concept analysis does not provide an efficient pseudo-intent calculation and does not handle large context. The proposed technique focused the issue of ontology heterogeneity that blocks the ontology interoperability and proposed a novel algorithm called pseudo-intent with backtracking-based FCA-Merge. The pseudo-intent with backtracking-based FCA-Merge algorithm performs four phases to merge the given two ontologies. In the first phase, it obtains the perfect attribute for the matching object using decision tree and pseudo intent technique. In the second phase, the obtained results are warehoused in the linked list as a formal context. In the third phase, the perfect relationship among formal contexts from the linked list has been identified using backtracking techniques. Finally, the merging phase performs the merging between the identified relations. The experimental outcome shows that the pseudo-intent with backtracking-based FCA-Merge provides 97% of precision, 82% of recall and 89% of accuracy which is better than the existing technique.

A novel approach for merging ontologies using formal concept analysis

Ontologies are mainly used for knowledge sharing and also as a knowledge structure. Due to the rising nature of ontologies, the method of merging information in the corporate realm turns to be critical. In the existing methods, formal concept analysis does not provide an efficient pseudo-intent calculation and does not handle large context. The proposed technique focused the issue of ontology heterogeneity that blocks the ontology interoperability and proposed a novel algorithm called pseudo-intent with backtracking-based FCA-Merge. The pseudo-intent with backtracking-based FCA-Merge algorithm performs four phases to merge the given two ontologies. In the first phase, it obtains the perfect attribute for the matching object using decision tree and pseudo intent technique. In the second phase, the obtained results are warehoused in the linked list as a formal context. In the third phase, the perfect relationship among formal contexts from the linked list has been identified using backtracking techniques. Finally, the merging phase performs the merging between the identified relations. The experimental outcome shows that the pseudo-intent with backtracking-based FCA-Merge provides 97% of precision, 82% of recall and 89% of accuracy which is better than the existing technique.

Merger and Acquisition of Business Organization and Its Impact on Human Resources

There is an assumption that, when merger and acquisition takes place, two companies join together will have greater value than the companies functioning alone, ie., to create synergy. Merger and acquisition among the companies are gaining its momentum, due to the enhanced competition among the corporates in domestic and the global market. This paper discusses about merger and acquisition and the motives behind it. Some mergers and acquisitions are unsuccessful due to some factors like financial, marketing and operational issues. Human resource problems in the merged companies also resulted in the failure of the mergers and acquisitions. So, this article proposes to discuss about HR issues at each phase of merger and acquisition, strategies to overcome the issues were also discussed.

Decline of the Current Quadrupole Moment during the Merger Phase of Binary Black Hole Coalescence

Utilizing the tools of tendex and vortex, we study the highly dynamic plunge and merger phases of several π -symmetric binary black hole coalescences. In particular, we observe a decline of the strength of the current quadrupole moment compared to that of the mass quadrupole moment during the merger phase, contrary to a naive estimate according to the dependence of these moments on the separation between the black holes. We further show that this decline of the current quadrupole moment is achieved through the remnants of the two individual spins becoming nearly aligned or anti-aligned with the total angular momentum. We also speculate on the ability to achieve a consistency between the electric and magnetic parity quasinormal modes.

Merger induced clump formation in distant infrared luminous starburst galaxies

While the formation of stellar clumps in distant galaxies is usually attributed to gravitational violent disk instabilities, we show here that major mergers also represent a competitive mechanism to form bright clumps. Using ∼0.1″ resolution ACS F814W images in the entire COSMOS field, we measured the fraction of clumpy emission in 109 main sequence (MS) and 79 Herschel-detected starbursts (off-MS) galaxies at 0.5 < z < 0.9, representative of normal versus merger induced star-forming activity, respectively. We additionally identify merger samples from visual inspection and from Gini-M20 morphological parameters. Regardless of the merger criteria adopted, the clumpiness distribution of merging systems is different from that of normal isolated disks at a > 99.5% confidence level. The former reaches higher clumpiness values up to 20% of the total galaxy emission. We confirm the merger induced clumpiness enhancement with novel hydrodynamical simulations of colliding galaxies with gas fractions typical of z ∼ 0.7. Multi-wavelength images of three starbursts in the CANDELS field support the young nature of clumps, which are likely merger products rather than older preexisting structures. Finally, for a subset of 19 starbursts with existing near-infrared rest frame spectroscopy, we find that the clumpiness is mildly anti-correlated with the merger phase, which decreases toward final coalescence. Our result can explain recent ALMA detections of clumps in hyperluminous high-z starbursts, while normal objects are smooth. This work raises a question as to the role of mergers on the origin of clumps in high redshift galaxies in general.

Quasinormal modes, echoes and the causal structure of the Green's function

Quasinormal modes describe the return to equilibrium of a perturbed system, in particular the ringdown phase of a black hole merger. But as globally-defined quantities, the quasinormal spectrum can be highly sensitive to global structure, including distant small perturbations to the potential. In what sense are quasinormal modes a property of the resulting black hole? We explore this question for the linearized perturbation equation with two potentials having disjoint bounded support. We give a composition law for the Wronskian that determines the quasinormal frequencies of the combined system. We show that over short time scales the evolution is governed by the quasinormal frequencies of the individual potentials, while the sensitivity to global structure can be understood in terms of echoes. We introduce an echo expansion of the Green's function and show that, as expected on general grounds, at any finite time causality limits the number of echoes that can contribute. We illustrate our results with the soluble example of a pair of δ-function potentials. We explicate the causal structure of the Green's function, demonstrating under what conditions two very different quasinormal spectra give rise to very similar ringdown waveforms.

Growth and disruption in the Lyra complex

Context. Nearby clusters of galaxies, z ≲ 0.1, are cosmic structures still under formation. Understanding the thermodynamic properties of merging clusters can provide crucial information on how they grow in the local universe. Aims. A detailed study of the intra-cluster medium (ICM) properties of un-relaxed systems is essential to understand the fate of in-falling structures and, more generally, the virialization process. Methods. We analyzed a mosaic of XMM-Newton observations (240 ks) of the Lyra system (z ∼ 0.067) that shows a complex dynamical state. Results. We find the main cluster RXC J1825.3+3026 to be in a late merger phase, whereas its companion CIZA J1824.1+3029 is a relaxed cool-core cluster. We estimate a mass ratio of ∼1 : 2 for the pair. No diffuse X-ray emission is found in the region between them, indicating that these clusters are in a pre-merger phase. We found evidence of a galaxy group infalling on RXC J1825.3+3026 in an advanced state of disruption. The SG, one of the brightest galaxies in the Lyra complex, was very likely at the center of the infalling group. This galaxy has a gaseous “corona” indicating that it was able to retain some of its gas after the ram-pressure stripping of the intra-group medium. In this scenario the diffuse emission excess observed southwest of RXC J1825.3+3026 could be due to gas once belonging to the group and/or to cluster ICM dislocated by the passage of the group. Finally, we identified three high-velocity galaxies aligned between RXC J1825.3+3026 and the SG, two of these showing evidence of gas stripped from them during infall. We estimate them to be currently falling onto the main cluster at an infall velocity of ∼3000 km s−1. Conclusions. Our study of the Lyra complex provides important clues about the processes presiding over the virialization of massive clusters in the local Universe.

Kicking gravitational wave detectors with recoiling black holes

Binary black holes emit gravitational radiation with net linear momentum leading to a retreat of the final remnant black hole that can reach up to $\sim5,000$ km/s. Full numerical relativity simulations are the only tool to accurately compute these recoils since they are largely produced when the black hole horizons are about to merge and they are strongly dependent on their spin orientations at that moment. We present eight new numerical simulations of BBH in the hangup-kick configuration family, leading to the maximum recoil. Black holes are equal mass and near maximally spinning ($|\vec{S}_{1,2}|/m_{1,2}^2=0.97$). Depending on their phase at merger, this family leads to $\sim\pm4,700$ km/s and all intermediate values of the recoil along the orbital angular momentum of the binary system. We introduce a new invariant method to evaluate the recoil dependence on the merger phase via the waveform peak amplitude used as a reference phase angle and compare it with previous definitions. We also compute the mismatch between these hangup-kick waveforms to infer their observable differentiability by gravitational wave detectors, such as advanced LIGO, finding currently reachable signal-to-noise ratios, hence allowing for the identification of highly recoiling black holes having otherwise essentially the same binary parameters.

The Pre-Deal Phase of Mergers and Acquisitions: A Review and Research Agenda

Despite the long-standing research interest in the pre-deal phase of mergers and acquisitions, many important questions remain unanswered. We review and synthesize the extensive but rather fragmented research on this topic area in the fields of management, finance, accounting, and economics. We organize our review according to six themes, that is, deal initiation, target selection, bidding and negotiation, valuation and financing, announcement, and closure, which represent the main categories of activities performed during the pre-deal phase. Our review shows that most of the existing research relies on a rather high-level, simplified, and static conception of the pre-deal phase. On the basis of our review, we put forward a research agenda that calls for a more granular examination of individual activities and decisions, a more comprehensive analysis of the interplay among the different actors involved in the pre-deal phase, a better understanding of the role of the temporal dynamics, and the extension of the theoretical base from variance-based to process-based theorizing.

The rotational profiles of cluster galaxies

ABSTRACT We compile two samples of cluster galaxies with complimentary hydrodynamic and N-body analysis using flash code to ascertain how their differing populations drive their rotational profiles and to better understand their dynamical histories. We select our main cluster sample from the X-ray Galaxy Clusters Database (BAX), which are populated with Sloan Digital Sky Survey (SDSS) galaxies. The BAX clusters are tested for the presence of substructures, acting as proxies for core mergers, culminating in sub-samples of eight merging and 25 non-merging galaxy clusters. An additional sample of 12 galaxy clusters with known dumbbell components is procured using galaxy data from the NASA/IPAC Extragalactic Database (NED) to compare against more extreme environments. BAX clusters of each sample are stacked on to a common RA–Dec. space to produce rotational profiles within the range of 0.0–2.5 r200. Merging stacks possess stronger core rotation at ≲0.5r200 primarily contributed by a red galaxy sub-population from relaxing core mergers; this is alongside high rotational velocities from blue galaxy sub-populations, until they mix and homogenize with the red sub-populations at ∼r200, indicative of an infalling blue galaxy sub-population with interactive mixing between both sub-populations at ≳ r200. flash code is utilized to simulate the merger phase between two originally independent clusters and test the evolution of their rotational profiles. Comparisons with the dumbbell clusters leads to the inference that the peculiar core rotations of some dumbbell clusters are the result of the linear motions of core galaxies relaxing on to the potential during post second infall.

Particle simulation studies of merging processes of two spherical-tokamak-type plasmoids

The merging processes of spherical-tokamak-type plasmoids (STs), which are confined in a rectangular conducting vessel, are investigated by means of a two-dimensional particle-in-cell simulation. A series of simulation runs with different mass ratios clarify that a starting time of the ST merging is nearly given by a transit time for an ion sound wave to travel from an inner edge of each ST in an initial profile to a reconnection point and a part of poloidal magnetic energy is transferred to the ion thermal energy and the electron thermal energy at the approximate rate of 3:1 during the ST merging process, which is almost independent of the mass ratio except for the smallest mass ratio case of (Mi/Me) = 100. This transfer process leads to the increases in a parallel component of electron temperature and a perpendicular component of ion temperature while keeping the other components almost constant. This is because the two-component electron distribution function with different velocity shifts along a toroidal magnetic field is formed around a reconnection point when two STs merge. On the other hand, an ion distribution function, consisting of three components with different velocity shifts perpendicular to the toroidal magnetic field, is formed around the reconnection point in the merging phase. It is also found that a sharp peak appears impulsively in the electron parallel temperature profile in the merging phase, which is consistent with the Mega Ampere Spherical Tokamak merging experiments [H. Tanabe et al., Nucl. Fusion 57, 056037 (2017)].