Model-independent test of gravity with a network of ground-based gravitational-wave detectors

The observation of gravitational waves with a global network of interferometric detectors such as advanced LIGO, advanced Virgo, and KAGRA will make it possible to probe into the nature of space-time structure. Besides Einstein's general theory of relativity, there are several theories of gravitation that passed experimental tests so far. The gravitational-wave observation provides a new experimental test of alternative theories of gravity because a gravitational wave may have at most six independent modes of polarization, of which properties and number of modes are dependent on theories of gravity. This paper proposes a method to reconstruct the independent modes of polarization in time-series data of an advanced detector network. Since the method does not rely on any specific model, it gives model-independent test of alternative theories of gravity

Cosmological test of gravity with polarizations of stochastic gravitational waves around 0.1-1 Hz

In general relativity, a gravitational wave has two polarization modes (tensor mode), but it could have additional polarizations (scalar and vector modes) in the early stage of the universe, where the general relativity may not strictly hold and/or the effect of higher-dimensional gravity may become significant. In this paper, we discuss how to detect extra-polarization modes of stochastic gravitational wave background (GWB), and study the separability of each polarization using future space-based detectors such as BBO and DECIGO. We specifically consider two plausible setups of the spacecraft constellations consisting of two and four clusters, and estimate the sensitivity to each polarization mode of GWBs. We find that a separate detection of each polarization mode is rather sensitive to the geometric configuration and distance between clusters and that the clusters should be, in general, separated by an appropriate distance. This seriously degrades the signal sensitivity, however, for suitable conditions, space-based detector can separately detect scalar, vector and tensor modes of GWBs with energy density as low as ~10^-15.Comment: 16 pages, 11 figure

Sense-making of consumer wellbeing in information technology-enabled services from a relational ontology position

Information technology (IT) built into products and services have become the key drivers for service innovation. How information technology-enabled services (ITESs) affect consumer wellbeing has increasingly become a concern to service scholars. In response to this, transformative service research (TSR) has emerged as a new stream in service research. This paper investigates consumer wellbeing derived from the consumption of ITESs in consumers’ daily lives. A mixed-method approach was employed in our study, including self-reflective reports, in-depth interviews and visual artistic methods. We demonstrated that a relational ontology, drawing on the ‘focal things’ concept (Borgmann, 1984) and sociomateriality (Orlikowski, 2009), could be used as a lens for us to understand consumer wellbeing in ITESs. We used four vignettes to demonstrate how relational ontology can enhance our understanding of consumer wellbeing in ITESs. Theoretically, this paper contributes to TSR by proposing and demonstrating the need to shift or at least extend the extant predominant technology ontology in marketing literature to make sense of consumer experiences and wellbeing in ITESs. In practice, this research encourages ITESs designers to emphasise the relational entanglement of technology with consumer routine practices in their service innovations for the purposes of consumer wellbeing

Visser's Massive Gravity Bimetric Theory Revisited

A massive gravity theory was proposed by Visser in the late nineties. This theory, based on a backgroung metric $b_{\alpha \beta}$ and on an usual dynamical metric $g_{\alpha \beta}$ has the advantage of being free of ghosts as well as discontinuities present in other massive theories proposed in the past. In the present investigation, the equations of Visser's theory are revisited with a particular care on the related conservation laws.\ It will be shown that a multiplicative factor is missing in the graviton tensor originally derived by Visser, which has no incidence on the weak field approach but becomes important in the strong field regime when, for instance, cosmological applications are considered. In this case, contrary to some previous claims found in the literature, we conclude that a non-static background metric is required in order to obtain a solution able to mimic the $\Lambda$CDM cosmology.Comment: 10 pages - Accepted for publication in Physical Review

The Music of the Aetherwave - B-mode Polarization in Einstein-Aether Theory

We study how the dynamical vector degree of freedom in modified gravity affects the CMB B-mode polarization in terms of the Einstein-aether theory. In this theory, vector perturbations can be generated from inflation, which can grow on superhorizon scales in the subsequent epochs and thereby leaves imprints on the CMB B-mode polarization. We derive the linear perturbation equations in a covariant formalism, and compute the CMB B-mode polarization using the CAMB code modified so as to incorporate the effect of the aether vector field. We find that the amplitude of the B-mode signal from the aether field can surpass the contribution from the inflationary gravitational waves for a viable range of model parameters. We also give an analytic argument explaining the shape of the spectrum based on the tight coupling approximation.Comment: 12 pages, 6 figure

Alternate Method of Phycocyanin Extraction

Phycocyanin is an abundant protein-pigment complex in many photosynthetic microbes and the feedstock for several emerging products in the food and pharmaceutical industries. The purpose of this project was to research the effectiveness of sonication technology to improve the efficiency and yields of phycocyanin production from the cyanobacterium Spirulina platensis. Sonication is the application of sound energy to agitate and break particles or cells. When used to augment the current methods of phycocyanin production, it has the potential benefit of reducing cell extraction volumes and increasing the yield of phycocyanin. Experiments were conducted to determine the effects of sonication time on the release of phycocyanin from concentrated S. platensis cell suspensions. The results show that sonication of a cell suspension containing 80 g dry weight S. platensis per 400 mL water for ~ 400 seconds provides maximum release of phycocyanin. The conventional method requires several hours of soaking 90 g dry weight S. platensis per 1000 mL water and achieves a lower degree of extraction. In summary, sonication can improve the efficiency of the conventional phycocyanin production process by shortening the time needed for initial release of phycocyanin from cells and with a smaller volume (more concentrated) cell suspension