Evidence for a 3 x 10^8 solar mass black hole in NGC 7052 from HST observations of the nuclear gas disk

We present an HST study of the nuclear region of the E4 radio galaxy NGC 7052, which has a nuclear disk of dust and gas. The WFPC2 was used to obtain B, V and I broad-band images and an H_alpha+[NII] narrow-band image. The FOS was used to obtain H_alpha+[NII] spectra along the major axis, using a 0.26 arcsec diameter circular aperture. The observed rotation velocity of the ionized gas is V = 155 +/- 17 km/s at r = 0.2 arcsec from the nucleus. The Gaussian dispersion of the emission lines increases from sigma = 70 km/s at r=1 arcsec, to sigma = 400 km/s on the nucleus. To interpret the gas kinematics we construct axisymmetric models in which the gas and dust reside in a disk in the equatorial plane of the stellar body. It is assumed that the gas moves on circular orbits, with an intrinsic velocity dispersion due to turbulence. The circular velocity is calculated from the combined gravitational potential of the stars and a possible nuclear black hole (BH). Models without a BH predict a rotation curve that is shallower than observed (V_pred = 92 km/s at r = 0.2 arcsec), and are ruled out at > 99% confidence. Models with a BH of 3.3^{+2.3}_{-1.3} x 10^8 solar masses provide an acceptable fit. NGC 7052 can be added to the list of active galaxies for which HST spectra of a nuclear gas disk provide evidence for the presence of a central BH. The BH masses inferred for M87, M84, NGC 6251, NGC 4261 and NGC 7052 span a range of a factor 10, with NGC 7052 falling on the low end. By contrast, the luminosities of these galaxies are identical to within 25%. Any relation between BH mass and luminosity, as suggested by independent arguments, must therefore have a scatter of at least a factor 10.Comment: 39 pages, LaTeX, with 16 PostScript figures. Submitted to the Astronomical Journal. Postscript version with higher resolution figures available from http://sol.stsci.edu/~marel/abstracts/abs_R22.htm

Роберт Конквест про голокост та голодомор

Purpose – Previous research has demonstrated strong relations between work characteristics (e.g. job demands and job resources) and work outcomes such as work performance and work engagement. So far, little attention has been given to the role of authenticity (i.e. employees’ ability to experience their true selves) in these relations. The purpose of this paper is to explore the relationship of state authenticity at work with job demands and resources on the one hand and work engagement, job satisfaction, and subjective performance on the other hand. Design/methodology/approach – In total, 680 Dutch bank employees participated to the study. Structural equation modelling was used to test the goodness-of-fit of the hypothesized model. Bootstrapping (Preacher and Hayes, 2008) was used to examine the meditative effect of state authenticity. Findings – Results showed that job resources were positively associated with authenticity and, in turn, that authenticity was positively related to work engagement, job satisfaction, and performance. Moreover, state authenticity partially mediated the relationship between job resources and three occupational outcomes. Research limitations/implications – Main limitations to this study were the application of selfreport questionnaires, utilization of cross-sectional design, and participation of a homogeneous sample. However, significant relationship between workplace characteristics, occupational outcomes, and state authenticity enhances our current understanding of the JD-R Model. Practical implications – Managers might consider enhancing state authenticity of employees by investing in job resources, since high levels of authenticity was found to be strongly linked to positive occupational outcomes. Originality/value – This study is among the first to examine the role of authenticity at workplace and highlights the importance of state authenticity for work-related outcomes

Organizing The Innovation System For Reusability: The Case Of Made-To-Order Markets

This paper examines the transfer of designs between projects within firm in the context of made-to-order producing companies. This practice is also known as knowledge reuse. Past studies has provided a detailed account of the strategies and processes involved in the reuse of technologies. Nonetheless, a large portion of this research was based on evidence collected in mass-producing companies. This paper attempts to develop a complementary framework to identify the strategies involved in reusing technologies in the made-to-order context. Data were drawn from three aerospace companies based in Israel. Two strategies emerged from the empirical evidence: exploit product success and design for reuse

New Constraints on the Efficiencies of Ram-Pressure Stripping and the Tidal Disruption of Satellite Galaxies

Using data from the Sloan Digital Sky Survey (SDSS) it has recently been shown that the red fraction of satellite galaxies increases with stellar mass. Semi-analytical models, however, predict red satellite fractions that are independent of stellar mass, and much higher than observed. It has been argued that this discrepancy owes to the fact that the models assume that satellite galaxies are instantaneously stripped of their hot gas reservoirs at the moment they are accreted into a bigger halo. In this letter we show that the fraction of red satellites can be brought in better agreement with the data by simply decreasing this stripping efficiency. However, this also results in a red fraction of massive centrals that is much too low. This owes to the fact that the massive centrals now accrete satellite galaxies that are bluer and more gas-rich. However, if a significant fraction of low mass satellite galaxies is tidally disrupted before being accreted by their central host galaxy, as suggested by recent studies, the red fractions of both centrals and satellites can be reproduced reasonably well. A problem remains with the red fraction of centrals of intermediate mass, which is likely to reflect an oversimplified treatment of AGN feedback.Comment: A few discussions added, updated to match the accepted version to ApJ Letter

Truncation of stellar disks in galaxies at z~1

We report here the first evidence for stellar disk truncation at high redshift, based on surface photometry of a sample of 16 high redshift (0.6 < z < 1.0) disk galaxies from the GOODS HST/ACS data. The radial profiles are best fit by a double exponential profile. This result agrees with the profile of disks in local galaxies. The cosmological surface brightness dimming at this redshift range only allows us to detect galaxies with spatially ``early'' truncation, R_br/h_in <= 3.5. Six galaxies show the radial double exponential structure, with an average value of R_br/h_in ~ 1.8. Such ``early'' truncated galaxies are missing in local samples so far. This result opens the ground for observing directly disk evolution through the study of the truncation radius as a function of redshift.Comment: 4 pages, 1 figure, accepted for publication in the A&A Letter

Two-Step lagrange interpolation method for the multilevel fast multipole algorithm

We present a two-step Lagrange interpolation method for the efficient solution of large-scale electromagnetics problems with the multilevel fast multipole algorithm (MLFMA). Local interpolations are required during aggregation and disaggregation stages of MLFMA in order to match the different sampling rates for the radiated and incoming fields in consecutive levels. The conventional one-step method is decomposed into two one-dimensional interpolations, applied successively. As it provides a significant acceleration in processing time, the proposed two-step method is especially useful for problems involving large-scale objects discretized with millions of unknowns. © 2006 IEEE

WFPC2 Images of the Central Regions of Early-Type Galaxies - I. The Data

We present high resolution R-band images of the central regions of 67 early-type galaxies obtained with the Wide Field and Planetary Camera 2 (WFPC2) aboard the Hubble Space Telescope (HST). Our sample strikingly confirms the complex morphologies of the central regions of early-type galaxies. In particular, we detect dust in 43 percent of all galaxies, and evidence for embedded stellar disks in a remarkably large fraction of 51 percent. In 14 of those galaxies the disk-like structures are misaligned with the main galaxy, suggesting that they correspond to stellar bars in S0 galaxies. We analyze the luminosity profiles of the galaxies in our sample, and classify galaxies according to their central cusp slope. To a large extent we confirm the clear dichotomy found in previous HST surveys: bright, boxy ellipticals with shallow inner cusps (`core' galaxies) on one hand and faint, disky ellipticals with steep central cusps (`power-law' galaxies) on the other hand. The advantages and shortcomings of classification schemes utilizing the extrapolated central cusp slope are discussed, and it is shown that this cusp slope might be an inadequate representation for galaxies whose luminosity profile slope changes smoothly with radius rather than resembling a broken power-law. In fact, we find evidence for an `intermediate' class of galaxies, that cannot unambiguously be classified as either core or power-law galaxies, and which have central cusp slopes and absolute magnitudes intermediate between those of core and power-law galaxies.Comment: 44 pages, 7 Postscript figures. Accepted for publication in the Astronomical Journal. The associated Appendix with figures of luminosity profiles, contour plots and isophotal parameters for all galaxies is available at http://www.astro.washington.edu/rest/centralpro

Semantic data set construction from human clustering and spatial arrangement

Abstract Research into representation learning models of lexical semantics usually utilizes some form of intrinsic evaluation to ensure that the learned representations reflect human semantic judgments. Lexical semantic similarity estimation is a widely used evaluation method, but efforts have typically focused on pairwise judgments of words in isolation, or are limited to specific contexts and lexical stimuli. There are limitations with these approaches that either do not provide any context for judgments, and thereby ignore ambiguity, or provide very specific sentential contexts that cannot then be used to generate a larger lexical resource. Furthermore, similarity between more than two items is not considered. We provide a full description and analysis of our recently proposed methodology for large-scale data set construction that produces a semantic classification of a large sample of verbs in the first phase, as well as multi-way similarity judgments made within the resultant semantic classes in the second phase. The methodology uses a spatial multi-arrangement approach proposed in the field of cognitive neuroscience for capturing multi-way similarity judgments of visual stimuli. We have adapted this method to handle polysemous linguistic stimuli and much larger samples than previous work. We specifically target verbs, but the method can equally be applied to other parts of speech. We perform cluster analysis on the data from the first phase and demonstrate how this might be useful in the construction of a comprehensive verb resource. We also analyze the semantic information captured by the second phase and discuss the potential of the spatially induced similarity judgments to better reflect human notions of word similarity. We demonstrate how the resultant data set can be used for fine-grained analyses and evaluation of representation learning models on the intrinsic tasks of semantic clustering and semantic similarity. In particular, we find that stronger static word embedding methods still outperform lexical representations emerging from more recent pre-training methods, both on word-level similarity and clustering. Moreover, thanks to the data set’s vast coverage, we are able to compare the benefits of specializing vector representations for a particular type of external knowledge by evaluating FrameNet- and VerbNet-retrofitted models on specific semantic domains such as “Heat” or “Motion.”</jats:p

Hallmarks of neurodegenerative diseases

Decades of research have identified genetic factors and biochemical pathways involved in neurodegenerative diseases (NDDs). We present evidence for the following eight hallmarks of NDD: pathological protein aggregation, synaptic and neuronal network dysfunction, aberrant proteostasis, cytoskeletal abnormalities, altered energy homeostasis, DNA and RNA defects, inflammation, and neuronal cell death. We describe the hallmarks, their biomarkers, and their interactions as a framework to study NDDs using a holistic approach. The framework can serve as a basis for defining pathogenic mechanisms, categorizing different NDDs based on their primary hallmarks, stratifying patients within a specific NDD, and designing multi-targeted, personalized therapies to effectively halt NDDs