5,427 research outputs found
Gravitational waves and stalled satellites from massive galaxy mergers at z <= 1
We present a model for merger-driven evolution of the mass function for
massive galaxies and their central supermassive black holes at late times. We
discuss the current observational evidence in favor of merger-driven massive
galaxy evolution during this epoch, and demonstrate that the observed evolution
of the mass function can be reproduced by evolving an initial mass function
under the assumption of negligible star formation. We calculate the stochastic
gravitational wave signal from the resulting black-hole binary mergers in the
low redshift universe (z <= 1) implied by this model, and find that this
population has a signal-to-noise ratio as much as ~5x larger than previous
estimates for pulsar timing arrays, with an expectation value for the
characteristic strain h_c (f=1 yr^{-1}) = 4.1 x 10^{-15} that may already be in
tension with observational constraints, and a {2-sigma, 3-sigma} lower limit
within this model of h_c (f=1 yr^{-1}) = {1.1 x 10^{-15}, 6.8 x 10^{-16}}. The
strength of this signal is sufficient to make it detectable with high
probability under conservative assumptions within the next several years, if
the principle assumption of merger-driven galaxy evolution since z = 1 holds
true. For cases where a galaxy merger fails to lead to a black hole merger, we
estimate the probability for a given number of satellite unmerged black holes
to remain within a massive host galaxy, and interpret the result in light of
ULX observations. In particular, we find that the brightest cluster galaxies
should have 1-2 such sources with luminosities above 10^{39} erg/s, which is
consistent with the statistics of observed ULXs.Comment: 11 pages, 5 figures, submitted to ApJ, v2 includes the referee's
requested change
Pengaruh Corporate Ability dan Corporate Social Responsibility terhadap Evaluasi Konsumen (Studi Produk Tolak Angin PT. Sidomuncul di Kota Semarang)
This study aims to investigate the influence of corporate abiliy and corporate social responsibility on consumer evaluations.The population in this research is the community Semarang user product Tolak Angin PT. Sidomuncul. Samples were taken as much as 85 respondents, the data collection technique using non-probability sampling method by purposive sampling technique. The method of data collection is done field research methods through observation, interviews with the questions and answers directly to the respondents , a list of questions (questionnaire) and the method of literature. Analysis of the data used is to use a validity test, reliability test, descriptive statistical analysis. Furthermore, in the analysis using multiple linear regression techniques. From the analysis in the corporate ability to know that a significant effect to evaluate the product and corporate social responsibility have a significant effect to evaluate the product. This study is expected to be overview of further research, if the same variable menggnakan this study to be more detailed and in-depth by taking into account the level of education and research dissemination city
A Dynamical Systems Approach to Schwarzschild Null Geodesics
The null geodesics of a Schwarzschild black hole are studied from a dynamical
systems perspective. Written in terms of Kerr-Schild coordinates, the null
geodesic equation takes on the simple form of a particle moving under the
influence of a Newtonian central force with an inverse-cubic potential. We
apply a McGehee transformation to these equations, which clearly elucidates the
full phase space of solutions. All the null geodesics belong to one of four
families of invariant manifolds and their limiting cases, further characterized
by the angular momentum L of the orbit: for |L|>|L_c|, (1) the set that flow
outward from the white hole, turn around, then fall into the black hole, (2)
the set that fall inward from past null infinity, turn around outside the black
hole to continue to future null infinity, and for |L|<|L_c|, (3) the set that
flow outward from the white hole and continue to future null infinity, (4) the
set that flow inward from past null infinity and into the black hole. The
critical angular momentum Lc corresponds to the unstable circular orbit at
r=3M, and the homoclinic orbits associated with it. There are two additional
critical points of the flow at the singularity at r=0. Though the solutions of
geodesic motion and Hamiltonian flow we describe here are well known, what we
believe is a novel aspect of this work is the mapping between the two
equivalent descriptions, and the different insights each approach can give to
the problem. For example, the McGehee picture points to a particularly
interesting limiting case of the class (1) that move from the white to black
hole: in the limit as L goes to infinity, as described in Schwarzschild
coordinates, these geodesics begin at r=0, flow along t=constant lines, turn
around at r=2M, then continue to r=0. During this motion they circle in azimuth
exactly once, and complete the journey in zero affine time.Comment: 14 pages, 3 Figure
The scientific merit of Carpobrotus mellei L. based on antimicrobial activity and chemical profiling
Species of the genus Carpobrotus are similar in appearance and have been used for medicinal
purposes over many generations. Carpobrotus mellei is endemic to the south-Western Cape of South
Africa, and also used for various ailments. To date no scientific validation and information has been
reported on C. mellei. This study investigated the antimicrobial potential of C. mellei against
Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Mycobacterium smegmatis,
and determined the minimum inhibitory concentrations (MIC) by two-fold serial dilution. C. mellei
showed antimicrobial activity against S. aureus and M. smegmatis in the disc diffusion method. Eight
chemical compounds showed clear zones of inhibition in the bioautograms, seven against S. aureus
and three compounds were active against M. smegmatis. The ethyl acetate extracts have MIC values of
7.5 mg/ml and 15 mg/ml against S. aureus and M. smegmatis, respectively. Phytochemical tests
indicated the presence of flavonoids, hydrolysable tannins, phytosterols and aromatic acids. High
performance liquid chromatography (HPLC) showed a species-specific spectrum at a wavelength of 280
nm. The results confirm that C. mellei has scientific merit, and can substitute one of the other
Carpobrotus species for antimicrobial usage within the south-Western Cape of South Africa
P120 catenin is required for morphogenetic movements involved in the formation of the eyes and the cranlofacial skeleton in Xenopus
ANALISIS FAKTOR-FAKTOR YANG BERPENGARUH TERHADAP AUDITOR SWITCHING SECARA VOLUNTARY (Studi Empiris pada Perusahaan Manufaktur yang Terdaftar di Bursa Efek Indonesia Tahun 2010-2014)
The purpose of this research is to analyze the factors that affect the replacement of public accountant on a voluntary basis in the manufacturing companies listed on the Indonesia Stock Exchange. The examined factors of this research are audit delay, audit opinion, company size, company growth, change in management, the financial condition of the company and the complexity of the company as the independent variable, while the auditor switching as the dependent variable.
The populations in this study are all manufacturing companies listed in the Indonesia Stock Exchange in the period 2010-2014 but for some variables needed data in previously. Data collection method used in the research is purposive sampling, based on predetermined criteria. A total 140 companies is used as sample company. Data were analyzed using logistic regression analysis.
Based on analytical results shows that variable audit delay and company size have a significant influence on voluntary auditor switching, while variable audit opinion, company growth, change in management, financial condition of the company and the complexity of the company doesn’t have significant influence on the companies decision to do voluntary auditor switching
Cigarette smoke regulates the expression of TLR4 and IL-8 production by human macrophages
<p>Abstract</p> <p>Background</p> <p>Toll-like receptors (TLRs) are present on monocytes and alveolar macrophages that form the first line of defense against inhaled particles. The importance of those cells in the pathophysiology of chronic obstructive pulmonary disease (COPD) has well been documented. Cigarette smoke contains high concentration of oxidants which can stimulate immune cells to produce reactive oxygen species, cytokines and chemokines.</p> <p>Methods</p> <p>In this study, we evaluated the effects of cigarette smoke medium (CSM) on TLR4 expression and interleukin (IL)-8 production by human macrophages investigating the involvement of ROS.</p> <p>Results and Discussion</p> <p>TLR4 surface expression was downregulated on short term exposure (1 h) of CSM. The downregulation could be explained by internalization of the TLR4 and the upregulation by an increase in TLR4 mRNA. IL-8 mRNA and protein were also increased by CSM. CSM stimulation increased intracellular ROS-production and decreased glutathione (GSH) levels. The modulation of TLR4 mRNA and surface receptors expression, IRAK activation, IκB-α degradation, IL-8 mRNA and protein, GSH depletion and ROS production were all prevented by antioxidants such as N-acetyl-L-cysteine (NAC).</p> <p>Conclusion</p> <p>TLR4 may be involved in the pathogenesis of lung emphysema and oxidative stress and seems to be a crucial contributor in lung inflammation.</p
Recommended from our members
Grain Growth in Thin Films with a Fibre Texture Studied by Phase-Field Simulations and Mean Field Modelling
The evolution of fiber textured structures is simulated in 2 dimensions using a generalized phase field model assuming two forms for the misorientation, a steady-state regime is reached after a finite amount of grain growth, where the numer and length weighted misorientation distribution functions (MDF) are constant in time, and the mean grain area A as a function of time t follows a power growth law A - A0 = kt^n with n close to 1 and A0 the initial mean grain area. The final shape of the MDF and value of the prefactor k in the power growth law clearly correlate with the misorientation dependence of the grain boundary energy. From a quantitative point of view, the fraction of special boundaries obtained in simulations is quite sensitive to the number of possible discrete orientations. Furthermore, a mean field approach is worked out to predict the growth exponent for systems with nonuniform grain boundary energy. The conclusions from the mean field approach are consistent with the simulation results.Physic
Fully broadband vAPP coronagraphs enabling polarimetric high contrast imaging
We present designs for fully achromatic vector Apodizing Phase Plate (vAPP)
coronagraphs, that implement low polarization leakage solutions and achromatic
beam-splitting, enabling observations in broadband filters. The vAPP is a pupil
plane optic, inducing the phase through the inherently achromatic geometric
phase. We discuss various implementations of the broadband vAPP and set
requirements on all the components of the broadband vAPP coronagraph to ensure
that the leakage terms do not limit a raw contrast of 1E-5. Furthermore, we
discuss superachromatic QWPs based of liquid crystals or quartz/MgF2
combinations, and several polarizer choices. As the implementation of the
(broadband) vAPP coronagraph is fully based on polarization techniques, it can
easily be extended to furnish polarimetry by adding another QWP before the
coronagraph optic, which further enhances the contrast between the star and a
polarized companion in reflected light. We outline several polarimetric vAPP
system designs that could be easily implemented in existing instruments, e.g.
SPHERE and SCExAO.Comment: 11 pages, 5 figures, presented at SPIE Astronomical Telescopes and
Instrumentation 201
- …