824 research outputs found
Good management improves productivity, but it may worsen environmental performance
The reduction of greenhouse gas (GHG) emissions is an increasingly important policy objective for many governments, both in developed and developing economies. This is reflected, among other things, in the emergence of energy efficiency as a high-priority topic on the policy agenda. In manufacturing – one of the key sectors from the point of view of GHG emissions and energy intensity – improvements in energy efficiency can come about from upgrading or closing existing plants or adding new production capacity that uses more modern technology. Moreover, recent research has found that management practices – such as those focused on how a firm handles a process-related problem, collection of production indicators, the timescale and difficulty of its targets and incentives – also play a significant role in reducing the energy intensity of firms
Magnetic ionization-thermal instability
Linear analysis of the stability of diffuse clouds in the cold neutral medium
with uniform magnetic field is performed. We consider that gas in equilibrium
state is heated by cosmic rays, X-rays and electronic photoeffect on the
surface of dust grains, and it is cooled by the collisional excitation of fine
levels of the CII. Ionization by cosmic rays and radiative recombinations is
taken into account. A dispersion equation is solved analytically in the
limiting cases of small and large wave numbers, as well as numerically in the
general case. In particular cases the dispersion equation describes thermal
instability of Field (1965) and ionization-coupled acoustic instability of
Flannery and Press (1979). We pay our attention to magnetosonic waves arising
in presence of magnetic field, in thermally stable region,
K and density n\lessapprox 10^3\,\mbox{cm}^{-3}. We have shown that these
modes can be unstable in the isobarically stable medium. The instability
mechanism is similar to the mechanism of ionization-coupled acoustic
instability. We determine maximum growth rates and critical wavelengths of the
instability of magnetosonic waves depending on gas temperature, magnetic field
strength and the direction of wave vector with respect to the magnetic field
lines. The minimum growth time of the unstable slow magnetosonic waves in
diffuse clouds is of Myr, minimum and the most unstable wavelengths lie
in ranges and pc, respectively. We discuss the application
of considered instability to the formation of small-scale structures and the
generation of MHD turbulence in the cold neutral medium.Comment: 11 pages, 9 figures, 2 tables, accepted for publication in MNRA
The Long Run Effects of R&D Place-based Policies: Evidence from Russian Science Cities
We study the long run effects of a unique historical place-based policies targeting R&D: the
creation of “Science Cities” in former Soviet Russia. The establishment of Science Cities and
the criteria for selecting their location were largely guided by political and military-strategic
considerations. We compare current demographic and economic characteristics of Science
Cities to those of appropriately matched localities that were similar to them at the time of
their establishment. We find that in the modern Russian economy, despite the massive cuts
of governmental support to R&D that followed the dissolution of the USSR, Science Cities
host more high-skilled workers and more developed R&D and ICT sectors; are the origin of
more international patents; and generally appear to be more productive and economically
developed. Within a spatial equilibrium framework, we interpret these findings as the result
of the interaction between persistence and agglomeration forces. Furthermore, we rule out
alternative explanations that have to do with the differential use of public resources, and
we find limited support for a case of equilibrium reversion. Finally, by analyzing firm-level
data we obtain evidence in favor of spillover effects with a wide spatial breadth
Optimization of Discrete Parameters Using the Adaptive Gradient Method and Directed Evolution
The problem is considered of optimizing discrete parameters in the presence
of constraints. We use the stochastic sigmoid with temperature and put forward
the new adaptive gradient method CONGA. The search for an optimal solution is
carried out by a population of individuals. Each of them varies according to
gradients of the 'environment' and is characterized by two temperature
parameters with different annealing schedules. Unadapted individuals die, and
optimal ones interbreed, the result is directed evolutionary dynamics. The
proposed method is illustrated using the well-known combinatorial problem for
optimal packing of a backpack (0-1 KP).Comment: 19 pages, 12 figure
Experimental and Numerical Investigation of Near-field Rotor Aeroacoustics
This work presents comparisons between experimental and numerical estimates of near-field rotor
aeroacoustics in hover. The experiments took place at the Kazan National Research Technical University
named after A. N. Tupolev (Kazan Aviation Institute). A set of rotor blades with NACA-0012 aerofoil sections
was used to obtain the sound pressure distribution using a linear array of microphones. It is shown that CFD
and experimental results are in good agreement suggesting that the obtained test data can be useful as a
validation case for development of CFD tools
Experimental and numerical study of rotor aeroacoustics
The work documents recent experiments at the Kazan National Research Technical University named after A.N. Tupolev (Kazan Aviation Institute), related to helicopter acoustics. The objective is to measure nar-field acoustics of rotors in hover and provide data suitable for computational fluid dynamics validation. The obtained set of data corresponds to a scaled rotor of known planform and the results are of high resolution. An advantage of the current dataset is that direct near-field acoustic data is made available and this allows for easy and direct comparisons with computational fluid dynamics predictions, without the need to use far-field aeroacoustic methods
Paleo-Balkan and Slavic Contributions to the Genetic Pool of Moldavians
Moldova has a rich historical and cultural heritage, which may be reflected in the current genetic makeup of its population.
To date, no comprehensive studies exist about the population genetic structure of modern Moldavians. To bridge this gap
with respect to paternal lineages, we analyzed 37 binary and 17 multiallelic (STRs) polymorphisms on the non-recombining
portion of the Y chromosome in 125 Moldavian males. In addition, 53 Ukrainians from eastern Moldova and 54 Romanians
from the neighboring eastern Romania were typed using the same set of markers. In Moldavians, 19 Y chromosome
haplogroups were identified, the most common being I-M423 (20.8%), R-M17* (17.6%), R-M458 (12.8%), E-v13 (8.8%), RM269*
and R-M412* (both 7.2%). In Romanians, 14 haplogroups were found including I-M423 (40.7%), R-M17* (16.7%), RM405
(7.4%), E-v13 and R-M412* (both 5.6%). In Ukrainians, 13 haplogroups were identified including R-M17 (34.0%), I-M423
(20.8%), R-M269* (9.4%), N-M178, R-M458 and R-M73 (each 5.7%). Our results show that a significant majority of the
Moldavian paternal gene pool belongs to eastern/central European and Balkan/eastern Mediterranean Y lineages.
Phylogenetic and AMOVA analyses based on Y-STR loci also revealed that Moldavians are close to both eastern/central
European and Balkan-Carpathian populations. The data correlate well with historical accounts and geographical location of
the region and thus allow to hypothesize that extant Moldavian paternal genetic lineages arose from extensive recent
admixture between genetically autochthonous populations of the Balkan-Carpathian zone and neighboring Slavic group
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