6,211 research outputs found
The Structure and the Distance of Collinder 121 from Hipparcos and Photometry: Resolving the Discrepancy
We present further arguments that the Hipparcos parallaxes for some of the
clusters and associations represented in the Hipparcos catalog should be used
with caution in the study of the Galactic structure. It has been already shown
that the discrepancy between the Hipparcos and ground based parallaxes for
several clusters including the Pleiades, Coma Ber and NGC 6231 can be resolved
by recomputing the Hipparcos astrometric solutions with an improved algorithm
diminishing correlated errors in the attitude parameters. Here we present new
parallaxes obtained with this algorithm for another group of stars with
discrepant data - the galactic cluster Cr 121. The original Hipparcos
parallaxes led de Zeeuw et al. to conclude that Cr 121 and the surrounding
association of OB stars form a relatively compact and coherent moving group at
a distance of 550 -- 600 pc. Our corrected parallaxes reveal a different
spatial distribution of young stellar populace in this area. Both the cluster
Cr 121 and the extended OB association are considerably more distant (750 --
1000 pc), and the latter has a large depth probably extending beyond 1 kpc.
Therefore, not only are the recalculated parallaxes in complete agreement with
the photometric uvbybeta parallaxes, but the structure of the field they reveal
is no longer in discrepancy with that found by the photometric method.Comment: 7 pages, 1 figure, ApJL accepte
The spatial distribution patterns of condensed phase post-blast explosive residues formed during detonation
The continued usage of explosive devices, as well as the ever growing threat of ‘dirty’ bombs necessitates a comprehensive understanding of particle dispersal during detonation events in order to develop effectual methods for targeting explosive and/or additive remediation efforts. Herein, the distribution of explosive analytes from controlled detonations of aluminised ammonium nitrate and an RDX-based explosive composition were established by systematically sampling sites positioned around each firing. This is the first experimental study to produce evidence that the post-blast residue mass can distribute according to an approximate inverse-square law model, while also demonstrating for the first time that distribution trends can vary depending on individual analytes. Furthermore, by incorporating blast-wave overpressure measurements, high-speed imaging for fireball volume recordings, and monitoring of environmental conditions, it was determined that the principle factor affecting all analyte dispersals was the wind direction, with other factors affecting specific analytes to varying degrees. The dispersal mechanism for explosive residue is primarily the smoke cloud, a finding which in itself has wider impacts on the environment and fundamental detonation theory
The costs and benefits of European immigration
In the early 21st century Europe is confronted with an ageing population, stagnating or even declining native populations, high unemployment and in the most key countries also with slow economic growth. At the same time Europe remains one of the prime destinations of international migration. Free movement of people is a means of creating an integrated Europe. Geographic mobility also helps on establishing a more efficient labour market, to the long-term benefit of workers, employers, taxpayers and EU Member States. Thus, our paper quantifies current migration patterns (see pp. 14-15); it recollects theoretical (see pp. 16-27) and empirical arguments (see pp. 28-47) on why immigration is so important, to what extent labour mobility allows individuals to improve their job prospects and employers to recruit people with adequate skills. The paper also discusses what kind of common European policies should be undertaken to optimise benefits of international migration. All our findings might not only avail understanding the economic impact of immigration. But they have policy implications for migrant receiving countries in Europe as well. The aim is to develop a better understanding of how the EU and its Member States could use availability and skills of today's and future immigrant populations in order to cope with economic and demographic challenges. --
Study of the Hydrophobin Genes in Verticillium Dahliae and Characterization of the Hydrophobin Gene VDH5
The broad host range, soil borne fungus Verticillium dahliae Kleb. is the causal agent of an economically significant vascular wilt disease. This species produces persistent resting structures, known as microsclerotia, which are the primary source of disease inoculum in the field. Five hydrophobin-like proteins (VDH1 to 5) have been identified in the genome of V. dahliae. The results of bioinformatics analyses suggested secretion of these proteins, and that they are all class II hydrophobins. Gene expression analyses of VDH1 to 5 indicate that the transcript levels of the individual genes vary under different growth conditions. Additionally, the transcript levels of these genes differ from one another. These results suggest that the members of this protein family have different roles in V. dahliae. One of the hydrophobin genes, VDH5, contains an extra domain known as an extended N terminus (ENT) domain. For further functional analyses of this particular hydrophobin, Agrobacterium tumefaciens-mediated transformation was used to generate a targeted gene disruption (vdh5TN), and gene deletion mutants (Δvdh5). Both Δvdh5 and vdh5TN strains showed reduced spores and microsclerotial production, as well as a less aggressive pathogenic phenotype. Similarly, a strain carrying a gene lacking the ENT domain was produced (vdh5ΔENT). No differences in development or pathogenicity were found between the vdh5ΔENT and the WT strains. The response of pathogenesis related genes (PR1, PR3, and PR5) in tomato plants inoculated with the Δvdh5 mutant, and with the mutant of the previously characterize vdh1, was also studied. The lower transcript levels of these genes in response to infection with either vdh1 or vdh5 mutant strain, compared to that of WT-inoculated plants, suggest that the plant is responding specifically to these two hydrophobin genes. The study and characterization of hydrophobin genes has proven their importance in developmental processes and in pathogenicity, and the knowledge produced here may lead to novel disease control methods
Correlation Between Gunung Padang and Sundanese Traditional Roof
Gunung Padang is the oldest prehistoric megaliths in Indonesia which has a function as a place of worship for the people who settled there about 2000BC according to its orientation and philosophy. Meanwhile after dark ages, people knowledge on building shelter arises therefore many traditional houses are build and had their philosophy implemented such as the vertical and horizontal beliefs in relation of human, nature, and divinity. This study concerns architecture identity correlation of place in the two eras because of cultural transition which can be observed until now. Gunung Padang has a similar vertical concept identity compare to Sundanese traditional roof according to both philosophy if the highest place is the most sacred place and describes the relationship between human, nature and divinity. The purpose of this study is to examine the correlation between Gunung Padang and the Sundanese traditional roof concept in religion and cultural aspect. Qualitative methods that leverages vernacular theory is used of the analysis methods
ALMA Observations of a Candidate Molecular Outflow in an Obscured Quasar
We present Atacama Large Millimeter/Submillimeter Array (ALMA) CO (1-0) and
CO (3-2) observations of SDSS J135646.10+102609.0, an obscured quasar and
ultra-luminous infrared galaxy (ULIRG) with two merging nuclei and a known
20-kpc-scale ionized outflow. The total molecular gas mass is M_{mol} ~
9^{+19}_{-6} x 10^8 Msun, mostly distributed in a compact rotating disk at the
primary nucleus (M_{mol} ~ 3 x 10^8 Msun) and an extended tidal arm (M_{mol} ~
5 x 10^8 Msun). The tidal arm is one of the most massive molecular tidal
features known; we suggest that it is due to the lower chance of shock
dissociation in this elliptical/disk galaxy merger. In the spatially resolved
CO (3-2) data, we find a compact (r ~ 0.3 kpc) high velocity (v ~ 500 km/s)
red-shifted feature in addition to the rotation at the N nucleus. We propose a
molecular outflow as the most likely explanation for the high velocity gas. The
outflowing mass of M_{mol} ~ 7 x 10^7 Msun and the short dynamical time of
t_{dyn} ~ 0.6 Myr yield a very high outflow rate of \dot{M}_{mol} ~ 350 Msun/yr
and can deplete the gas in a million years. We find a low star formation rate
(< 16 Msun/yr from the molecular content and < 21 Msun/yr from the far-infrared
spectral energy distribution decomposition) that is inadequate to supply the
kinetic luminosity of the outflow (\dot{E} ~ 3 x 10^43 erg/s). Therefore, the
active galactic nucleus, with a bolometric luminosity of 10^46 erg/s, likely
powers the outflow. The momentum boost rate of the outflow (\dot{p}/(Lbol/c) ~
3) is lower than typical molecular outflows associated with AGN, which may be
related to its compactness. The molecular and ionized outflows are likely two
distinct bursts induced by episodic AGN activity that varies on a time scale of
10^7 yr.Comment: 16 pages, 7 figures, ApJ accepte
Pengaruh Pertumbuhan Penjualan, Profitabilitas, Struktur Aktiva dan Ukuran Perusahaan terhadap Struktur Modal pada Perusahaan Pariwisata dan Perhotelan di BEI
Financial management consists of three decisions, namely investment decisions, financing decisions and dividend policy. Financing decisions are influenced by capital structure. The capital structure is important to the company because it has the effect to the company's financial position, and the managers in a company should be able to know what factors affect the capital structure, it is intended that the company can maximize shareholder wealth. This study with the aim to determine the effect sales growth, profitability, asset structure and firm size on the capital structure. Location of the study is the tourism and hospitality companies in the period 2007-2011 IDX. The method of sample selection in this study is purposive sampling method, the sample is 10 samples. Methods of data collection is done through non - participant observation. The analysis technique used is multiple linear regression. The results showed that the sales growth, profitability, asset structure and firm size jointly have a significant effect . Sales growth has a significant negative effect on capital structure. Profitability significant positive effect on capital structure. Asset structure has a positive effect on capital structure. Firm size has a positive and significant impact on the capital structure
Analysis of Hydrogen Cyanide Hyperfine Spectral Components towards Star Forming Cores
Although hydrogen cyanide has become quite a common molecular tracing species
for a variety of astrophysical sources, it, however, exhibits dramatic non-LTE
behaviour in its hyperfine line structure. Individual hyperfine components can
be strongly boosted or suppressed. If these so-called hyperfine line anomalies
are present in the HCN rotational spectra towards low or high mass cores, this
will affect the interpretation of various physical properties such as the line
opacity and excitation temperature in the case of low mass objects and infall
velocities in the case of their higher mass counterparts. This is as a
consequence of the direct effects that anomalies have on the underlying line
shape, be it with the line structural width or through the inferred line
strength. This work involves the first observational investigation of these
anomalies in two HCN rotational transitions, J=1!0 and J=3!2, towards both low
mass starless cores and high mass protostellar objects. The degree of anomaly
in these two rotational transitions is considered by computing the ratios of
neighboring hyperfine lines in individual spectra. Results indicate some degree
of anomaly is present in all cores considered in our survey, the most likely
cause being line overlap effects among hyperfine components in higher
rotational transitions.Comment: 8th Serbian Conference on Spectral Line Shapes in Astrophysics,
Divicibare; 8 pages, 5 figure
Observations of Feedback from Radio-Quiet Quasars: I. Extents and Morphologies of Ionized Gas Nebulae
Black hole feedback -- the strong interaction between the energy output of
supermassive black holes and their surrounding environments -- is routinely
invoked to explain the absence of overly luminous galaxies, the black hole vs.
bulge correlations and the similarity of black hole accretion and star
formation histories. Yet direct probes of this process in action are scarce and
limited to small samples of active nuclei. We present Gemini IFU observations
of the distribution of ionized gas around luminous, obscured, radio-quiet (RQ)
quasars at z~0.5. We detect extended ionized gas nebulae via [O III]5007
emission in every case, with a mean diameter of 28 kpc. These nebulae are
nearly perfectly round. The regular morphologies of nebulae around RQ quasars
are in striking contrast with lumpy or elongated nebulae seen around radio
galaxies at low and high redshifts. We present the uniformly measured
size-luminosity relationship of [O III] nebulae around Seyfert 2 galaxies and
type 2 quasars spanning 6 orders of magnitude in luminosity and confirm the
flat slope of the correlation (R ~ L^{0.25+/-0.02}). We find a universal
behavior of the [O III]/H-beta ratio in our entire RQ quasar sample: it
persists at a constant value (~10) in the central regions, until reaching a
"break" isophotal radius ranging from 4 to 11 kpc where it starts to decrease.
We propose a model of clumpy nebulae in which clouds that produce line emission
transition from being ionization-bounded at small distances from the quasar to
being matter-bounded in the outer parts of the nebula, which qualitatively
explains the observed line ratio and surface brightness profiles. It is
striking that we see such smooth and round large-scale gas nebulosities in this
sample, which are inconsistent with illuminated merger debris and which we
suggest may be the signature of accretion energy from the nucleus reaching gas
at large scales.Comment: 44 pages, 11 figures, 3 tables. Accepted for publication in MNRA
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