26,652 research outputs found
Russian manufacturing and the threat of ‘Dutch disease’: a comparison of competitiveness developments in Russian and Ukrainian industry
This paper examines the development of Russian industry in comparison with that of Ukrainian industry during 1995–2004 in an effort to ascertain to what extent, if any, Russian manufacturing showed signs of succumbing to ‘Dutch disease’. Ukraine and Russia began the market transition with broadly similar institutions, industrial structures and levels of technology, and the economic reforms implemented in the two countries were also similar, although Ukraine was reckoned to lag behind Russia in many areas. The main difference between them is Russia’s far greater resource wealth. It follows that differences in industrial development since 1991 may to some degree be attributable to differences in initial natural resource endowments. In short, Ukraine could provide a rough approximation of how a resource-poor Russia might have developed over the transition
Vacuum field energy and spontaneous emission in anomalously dispersive cavities
Anomalously dispersive cavities, particularly white light cavities, may have
larger bandwidth to finesse ratios than their normally dispersive counterparts.
Partly for this reason, their use has been proposed for use in LIGO-like
gravity wave detectors and in ring-laser gyroscopes. In this paper we analyze
the quantum noise associated with anomalously dispersive cavity modes. The
vacuum field energy associated with a particular cavity mode is proportional to
the cavity-averaged group velocity of that mode. For anomalously dispersive
cavities with group index values between 1 and 0, this means that the total
vacuum field energy associated with a particular cavity mode must exceed . For white light cavities in particular, the group index approaches
zero and the vacuum field energy of a particular spatial mode may be
significantly enhanced. We predict enhanced spontaneous emission rates into
anomalously dispersive cavity modes and broadened laser linewidths when the
linewidth of intracavity emitters is broader than the cavity linewidth.Comment: 9 pages, 4 figure
Estimation of the methane emission factor for the Italian Mediterranean buffalo
In order to contribute to the improvement of the national greenhouse gas emission inventory, this work aimed at estimating a country-specific enteric methane (CH4) emission factor for the Italian Mediterranean buffalo. For this purpose, national agriculture statistics, and information on animal production and farming conditions were analysed, and the emission factor was estimated using the Tier 2 model of the Intergovernmental Panel on Climate Change. Country-specific CH4 emission factors for buffalo cows (630 kg body weight, BW) and other buffalo (313 kg BW) categories were estimated for the period 1990–2004. In 2004, the estimated enteric CH4 emission factor for the buffalo cows was 73 kg/head per year, whereas that for other buffalo categories it was 56 kg/head per year. Research in order to determine specific CH4 conversion rates at the predominant production system is suggested
Investigating the Relation between Galaxy Properties and the Gaussianity of the Velocity Distribution of Groups and Clusters
We investigate the dependence of stellar population properties of galaxies on
group dynamical stage for a subsample of Yang catalog. We classify groups
according to their galaxy velocity distribution into Gaussian (G) and
Non-Gaussian (NG). Using two totally independent approaches we have shown that
our measurement of Gaussianity is robust and reliable. Our sample covers Yang's
groups in the redshift range 0.03 z 0.1 having mass
10. The new method, Hellinger Distance (HD), to determine
whether a group has a velocity distribution Gaussian or Non-Gaussian is very
effective in distinguishing between the two families. NG groups present halo
masses higher than the G ones, confirming previous findings. Examining the
Skewness and Kurtosis of the velocity distribution of G and NG groups, we find
that faint galaxies in NG groups are mainly infalling for the first time into
the groups. We show that considering only faint galaxies in the outskirts,
those in NG groups are older and more metal rich than the ones in G groups.
Also, examining the Projected Phase Space of cluster galaxies we see that
bright and faint galactic systems in G groups are in dynamical equilibrium
which does not seem to be the case in NG groups. These findings suggest that NG
systems have a higher infall rate, assembling more galaxies which experienced
preprocessing before entering the group.Comment: 55 pages, 5 Tables and 12 Figures. Accepted for publication in
Astronomical Journa
Complexity analysis of Klein-Gordon single-particle systems
The Fisher-Shannon complexity is used to quantitatively estimate the
contribution of relativistic effects to on the internal disorder of
Klein-Gordon single-particle Coulomb systems which is manifest in the rich
variety of three-dimensional geometries of its corresponding quantum-mechanical
probability density. It is observed that, contrary to the non-relativistic
case, the Fisher-Shannon complexity of these relativistic systems does depend
on the potential strength (nuclear charge). This is numerically illustrated for
pionic atoms. Moreover, its variation with the quantum numbers (n, l, m) is
analysed in various ground and excited states. It is found that the
relativistic effects enhance when n and/or l are decreasing.Comment: 4 pages, 3 figures, Accepted in EPL (Europhysics Letters
Star formation in the giant HII regions of M101
The molecular components of three giant HII regions (NGC 5461, NGC 5462, NGC
5471) in the galaxy M101 are investigated with new observations from the James
Clerk Maxwell Telescope, the NRAO 12-meter, and the Owens Valley millimeter
array. Of the three HII regions, only NGC 5461 had previously been detected in
CO emission.
We calculate preliminary values for the molecular mass of the GMCs in NGC
5461 by assuming a CO-to-H_2 factor (X factor) and then compare these values
with the virial masses. We conclude that the data in this paper demonstrate for
the first time that the value of X may decrease in regions with intense star
formation.
The molecular mass for the association of clouds in NGC 5461 is approximately
3x10^7 Mo and is accompanied by 1-2 times as much atomic mass. The observed CO
emission in NGC 5461 is an order of magnitude stronger than in NGC 5462, while
it was not possible to detect molecular gas toward NGC 5471 with the JCMT. An
even larger ratio of atomic to molecular gas in NGC 5471 was observed, which
might be attributed to efficient conversion of molecular to atomic gas.
The masses of the individual clouds in NGC 5461, which are gravitationally
bound, cover a range of (2-8) x 10^5 Mo, comparable with the masses of Galactic
giant molecular clouds (GMCs). Higher star forming efficiencies, and not
massive clouds, appear to be the prerequisite for the formation of the large
number of stars whose radiation is required to produce the giant HII regions in
M101.Comment: 32 pages, 5 figures, accepted for publication in the Astrophysical
Journa
Structural anisotropy and orientation-induced Casimir repulsion in fluids
In this work we theoretically consider the Casimir force between two periodic
arrays of nanowires (both in vacuum, and on a substrate separated by a fluid)
at separations comparable to the period. Specifically, we compute the
dependence of the exact Casimir force between the arrays under both lateral
translations and rotations. Although typically the force between such
structures is well-characterized by the Proximity Force Approximation (PFA), we
find that in the present case the microstructure modulates the force in a way
qualitatively inconsistent with PFA. We find instead that effective-medium
theory, in which the slabs are treated as homogeneous, anisotropic dielectrics,
gives a surprisingly accurate picture of the force, down to separations of half
the period. This includes a situation for identical, fluid-separated slabs in
which the exact force changes sign with the orientation of the wire arrays,
whereas PFA predicts attraction. We discuss the possibility of detecting these
effects in experiments, concluding that this effect is strong enough to make
detection possible in the near future.Comment: 12 pages, 9, figure. Published version with expanded discussio
Sub-au imaging of water vapour clouds around four Asymptotic Giant Branch stars
We present MERLIN maps of the 22-GHz H2O masers around four low-mass
late-type stars (IK Tau U Ori, RT Vir and U Her), made with an angular
resolution of ~ 15 milliarcsec and a velocity resolution of 0.1 km s-1. The H2O
masers are found in thick expanding shells with inner radii ~ 6 to 16 au and
outer radii four times larger. The expansion velocity increases radially
through the H2O maser regions, with logarithmic velocity gradients of 0.5--0.9.
IK Tau and RT Vir have well-filled H2O maser shells with a spatial offset
between the near and far sides of the shell, which suggests that the masers are
distributed in oblate spheroids inclined to the line of sight. U Ori and U Her
have elongated poorly-filled shells with indications that the masers at the
inner edge have been compressed by shocks; these stars also show OH maser
flares. MERLIN resolves individual maser clouds, which have diameters of 2 -- 4
au and filling factors of only ~ 0.01 with respect to the whole H2O maser
shells. The CSE velocity structure gives additional evidence the maser clouds
are density bounded. Masing clouds can be identified over a similar timescale
to their sound crossing time (~2 yr) but not longer. The sizes and observed
lifetimes of these clouds are an order of magnitude smaller than those around
red supergiants, similar to the ratio of low-mass:high-mass stellar masses and
sizes. This suggests that cloud size is determined by stellar properties, not
local physical phenomena in the wind.Comment: 21 pages, including 14 figures and 8 tables. Accepted for publication
in MNRA
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