302 research outputs found
Effects of Preheated Clusters on the CMB Spectrum
Mounting evidence from -ray observations reveals that bound objects should
receive some form of energy in the past injected from non-gravitaional sources.
We report that an instantaneous heating scheme, for which gases in dense
regions were subjected to a temperature jump of 1keV at whereas those in
rarified regions remained intact, can produce bound objects obeying the
observed mass-temperature and luminosity-temperature relations. Such preheating
lowers the peak Sunyaev-Zeldovich (SZ) power by a factor of 2 and exacerbates
the need for the normalization of matter fluctuations to assume an
extreme high value for the SZ signals to account for the excess
anisotropy on 5-arcminute scale detected by the Cosmic Background Imager in the
cosmic microwave background radiation.Comment: 6 pages, 3 figs, submitted to ApJL. Corrected for a normalization
problem and one more simulation result is included. Conclusion has been
reversed. Motion pictures of simulations can be found at
http://asweb.phys.ntu.edu.tw/~tseng/MEMO/SZE.htm
Hydrodynamical simulations of colliding jets:modeling 3C 75
Radio observations suggest that 3C 75, located in the dumbbell shaped galaxy
NGC 1128 at the center of Abell 400, hosts two colliding jets. Motivated by
this source, we perform three-dimensional hydrodynamical simulations using a
modified version of the GPU-accelerated Adaptive-MEsh-Refinement hydrodynamical
parallel code () to study colliding extragalactic jets. We find
that colliding jets can be cast into two categories: 1) bouncing jets, in which
case the jets bounce off each other keeping their identities, and 2) merging
jets, when only one jet emerges from the collision. Under some conditions the
interaction causes the jets to break up into oscillating filaments of opposite
helicity, with consequences for their downstream stability. When one jet is
significantly faster than the other and the impact parameter is small, the jets
merge; the faster jet takes over the slower one. In the case of merging jets,
the oscillations of the filaments, in projection, may show a feature which
resembles a double helix, similar to the radio image of 3C 75. Thus we
interpret the morphology of 3C 75 as a consequence of the collision of two jets
with distinctly different speeds at a small impact parameter, with the faster
jet breaking up into two oscillating filaments.Comment: 13 pages, 9 figures, accepted for publication in Ap
AMiBA: Array for Microwave Background Anisotropy
As part of a 4-year Cosmology and Particle Astrophysics (CosPA) Research
Excellence Initiative in Taiwan, AMiBA a 19-element dual-channel 85-105 GHz
interferometer array is being specifically built to search for high redshift
clusters of galaxies via the Sunyaev-Zeldovich Effect (SZE). In addition, AMiBA
will have full polarization capabilities, in order to probe the polarization
properties of the Cosmic Microwave Background. AMiBA, to be sited on Mauna Kea
in Hawaii or in Chile, will reach a sensitivity of mJy or 7K in 1
hour. The project involves extensive international scientific and technical
collaborations. The construction of AMiBA is scheduled to starting operating in
early 2004.Comment: Contribution to IAU Symposium 201, `New Cosmological Data and the
Values of the Fundamental Parameters', eds. A Lasenby and A Wilkinson; 6
pages including 2 figures. Also available form the AMiBA website at
http://www.asiaa.sinica.edu.tw/amiba/papers/iauamiba.tar.gz. Minor
corrections in text
Can We Detect the Color–Density Relation with Photometric Redshifts?
A variety of methods have been proposed to define and to quantify galaxy environments. While these techniques work well in general with spectroscopic redshift samples, their application to photometric redshift surveys remains uncertain. To investigate whether galaxy environments can be robustly measured with photo-z samples, we quantify how the density measured with the nearest-neighbor approach is affected by photo-z uncertainties by using the Durham mock galaxy catalogs in which the 3D real-space environments and the properties of galaxies are known exactly. Furthermore, we present an optimization scheme in the choice of parameters used in the 2D projected measurements that yield the tightest correlation with respect to the 3D real-space environments. By adopting the optimized parameters in the density measurements, we show that the correlation between the 2D projected optimized density and the real-space density can still be revealed, and the color–density relation is also visible out to z ~ 0.8 even for a photo-z uncertainty () up to 0.06. We find that at redshifts 0.3 < z < 0.5 a deep (i ~ 25) photometric redshift survey with yields a performance in small-scale density measurement that is comparable to a shallower i ~ 22.5 spectroscopic sample with ~10% sampling rate. Finally, we discuss the application of the local density measurements to the Pan-STARRS1 Medium Deep Survey (PS-MDS), one of the largest deep optical imaging surveys. Using data from ~5 square degrees of survey area, our results show that it is possible to measure local density and to probe the color–density relation with 3σ confidence level out to z ~ 0.8 in the PS-MDS. The color–density relation, however, quickly degrades for data covering smaller areas
Genotypic analysis of genes associated with transmission and drug resistance in the Beijing lineage of Mycobacterium tuberculosis
AbstractThe Beijing genotype of Mycobacterium tuberculosis is an endemic lineage in East Asia that has disseminated worldwide. It is a major health concern, as it is geographically widespread and is considered to be hypervirulent. To elucidate its genetic diversity in Taiwan, phylogenetic reconstruction was performed using 338 M. tuberculosis Beijing family clinical isolates. Region-of-difference analysis revealed the strains from Taiwan to be distributed among six subgroups of a phylogenetic tree. Synonymous single nucleotide polymorphisms at 10 chromosomal positions were also analysed. Among the 338 isolates analysed for single-nucleotide polymorphisms by using mass spectrometry, the most frequent strain found was ST10 (53.3%), followed by ST19 (14.8%) and ST22 (14.5%). Tests of drug resistance showed that the sublineages ST10, ST19 and ST26 were over-represented in the multidrug-resistant population. The presence of mutations in putative genes coding for DNA repair enzymes, which could confer a mutator phenotype to facilitate spreading of the pathogen, did not demonstrate an association with multidrug resistance. Therefore, the DNA repair genes may be involved in transmission but not in drug resistance
Problems of innovative receptivity of personnel of enterprises of industrial automation
Стаття присвячена аналізу галузі промислової автоматики (ПА), позначенню та з’ясовуванню проблематики у підприємств ПА для поліпшення інноваційної діяльності (ІД) шляхом комплексного підвищення інноваційної сприйнятливості (ІС) персоналу в системі управління персоналом. Показана динаміка виробничих економічних показників українських підприємств ПА за 2011-2017 рр., запропоновані рекомендації по підвищенню ІС персоналу. Наведено аналіз техніко-економічних показників підприємств ПА. Приведений загальний огляд реалізації продукції (товарів, послуг за видами економічної діяльності) на Україні за період 2010-2017 рр. Для дослідження приведена методологія порівняльного аналізу. Результати дослідження показують виявлення проблем підприємств ПA, які полягають у збільшенні реалізованої продукції і зниженні прибутку, що говорить про необхідність підвищення IС персоналу в системі управління персоналом.The article is devoted to the analysis of industrial areas in particular the field of industrial automation (ІA), the identification and clarification of problems in PA enterprises, to improve innovation activity (IА) through a comprehensive increase in the innovative receptivity (IR) of personnel in the personnel management system. The industrial enterprises of Ukraine and in particular industry of ІА now experiences heavy times of competitive activity with foreign companies and in particular with more cheap commodities from China. Not to lose the positions and occupy new markets it is needed not only to watch after novelties in the field of productive but also in the sphere of personnel and increase of him ІR for the increase of competitiveness. The dynamics of the production of economic indicators of the Ukrainian enterprises of IA for 2011-2017 is shown, recommendations for increasing the executive personnel are offered. The analysis of technical and economic indicators of IA enterprises is given. And also provides a general overview of the sale of products (goods,
services by type of economic activity) in Ukraine for the period 2010-2017. For research methodology over of comparative analysis is brought. Research results are exposures of problems of enterprises of IA such as an increase of the realized products and decline of profit, that talks at the necessity of increase of IR of personnel, in control system by a personnel. Innovative activity of every enterprise of industrial automation (IA) is important for the increase of competitiveness and increase arrived. The innovative oriented skilled personnel
failing in the Ukrainian enterprises, what called to provide development and increase of efficiency of activity of enterprises. For development normatively of technical documentation on a management and development of personnel experience of front-rank world companies is poorly used what track is adapted to take into account taking into account Ukrainian realities. To the necessity of development of control system by a personnel with the purpose of leading to of them to the standards of front-rank world companies
Time delay between images of the lensed quasar UM673
We study brightness variations in the double lensed quasar UM673 (Q0142-100)
with the aim of measuring the time delay between its two images. In the paper
we combine our previously published observational data of UM673 obtained during
the 2003 - 2005 seasons at the Maidanak Observatory with archival and recently
observed Maidanak and CTIO UM673 data. We analyze the V, R and I-band light
curves of the A and B images of UM673, which cover ten observational seasons
from August 2001 to November 2010. We also analyze the time evolution of the
difference in magnitudes between images A and B of UM673 over more than ten
years. We find that the quasar exhibits both short-term (with amplitude of \sim
0.1 mag in the R band) and high-amplitude (\sim 0.3 mag) long-term variability
on timescales of about several months and several years, respectively. These
brightness variations are used to constrain the time delay between the images
of UM673. From cross-correlation analysis of the A and B quasar light curves
and error analysis we measure the mean time delay and its error of 89 \pm11
days. Given the input time delay of 88 days, the most probable value of the
delay that can be recovered from light curves with the same statistical
properties as the observed R-band light curves of UM673 is 95{+5/-16}{+14/-29}
days (68 and 95 % confidence intervals). Analysis of the V - I color variations
and V, R and I-band magnitude differences of the quasar images does not show
clear evidence of the microlensing variations between 1998 and 2010.Comment: Submitted to A&A, 11 pages, 9 figure
Density waves in the shearing sheet V. Feedback cycle for swing amplification by non-linear effects
Non-linear effects in the dynamical evolution of a shearing sheet made of
stars are studied. First the implications of hitherto neglected non-linearities
of the Boltzmann equation for the dynamical evolution of the shearing sheet are
investigated. Using a formalism developed previously on the basis of the
linearized Boltzmann equation it is demonstrated that the inclusion of the
non-linear term leads to a feedback cycle for swing amplified density waves in
the unbounded shearing sheet. Such a feedback is unique to star disks and is
not known for gas disks. In order to present concrete examples of the
non-linear feedback cycle a SCF code was developed and numerical simulations of
the dynamical evolution of the shearing sheet are performed. The numerical
results seem to confirm the theoretical predictions. The evolution of the
shearing sheet resembles closely and might actually explain the recurrent
spiral instabilities found in large-scale numerical simulations of the
dynamical evolution of galactic disks.Comment: 13 pages, 11 figures, accepted by Astron. Astrophy
AMiBA: scaling relations between the integrated Compton-y and X-ray derived temperature, mass, and luminosity
We investigate the scaling relations between the X-ray and the thermal
Sunyaev-Zel'dovich Effect (SZE) properties of clusters of galaxies, using data
taken during 2007 by the Y.T. Lee Array for Microwave Background Anisotropy
(AMiBA) at 94 GHz for the six clusters A1689, A1995, A2142, A2163, A2261, and
A2390. The scaling relations relate the integrated Compton-y parameter Y_{2500}
to the X-ray derived gas temperature T_{e}, total mass M_{2500}, and bolometric
luminosity L_X within r_{2500}. Our results for the power-law index and
normalization are both consistent with the self-similar model and other studies
in the literature except for the Y_{2500}-L_X relation, for which a physical
explanation is given though further investigation may be still needed. Our
results not only provide confidence for the AMiBA project but also support our
understanding of galaxy clusters.Comment: Accepted by ApJ; 8 pages, 3 figures, 5 table
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