4,084 research outputs found
Химический состав донных отложений реки Васюган и ее притоков
Приведены результаты изучения химического состава донных отложений реки Васюган Томской области и ее притоков. Установлен средний за 1997-2005 гг. уровень содержания нефтепродуктов и более 20-и химических элементов. Выявлены взаимосвязи между концентрациями нефтепродуктов и хлорид-иона в донных отложениях и речных водах. Показано, что донные отложения водотоков в среднем по бассейну реки Васюган характеризуются как умеренно загрязненные и загрязненные
H2O Maser Observations of Candidate Post-AGB Stars and Discovery of Three High-velocity Water Sources
We present the results of 22 GHz H_2O maser observations of a sample of 85
post-Asymptotic Giant Branch (post-AGB) candidate stars, selected on the basis
of their OH 1612 MHz maser and far-infrared properties. All sources were
observed with the Tidbinbilla 70-m radio telescope and 21 detections were made.
86 GHz SiO Mopra observations of a subset of the sample are also presented. Of
the 21 H_2O detections, 15 are from sources that are likely to be massive AGB
stars and most of these show typical, regular H_2O maser profiles. In contrast,
nearly all the detections of more evolved stars exhibited high-velocity H_2O
maser emission. Of the five sources seen, v223 (W43A, IRAS 18450-0148) is a
well known `water-fountain' source which belongs to a small group of post-AGB
stars with highly collimated, high-velocity H_2O maser emission. A second
source in our sample, v270 (IRAS 18596+0315), is also known to have
high-velocity emission. We report the discovery of similar emission from a
further three sources, d46 (IRAS 15445-5449), d62 (IRAS 15544-5332) and b292
(IRAS 18043-2116). The source d46 is an evolved post-AGB star with highly
unusual maser properties. The H_2O maser emission from d62 is probably
associated with a massive star. The source b292 is a young post-AGB star that
is highly likely to be a water-fountain source, with masers detected over a
velocity range of 210 km s^{-1}.Comment: 47 pages, 9 figures, 4 tables, accepted by Ap
Block Spin Effective Action for 4d SU(2) Finite Temperature Lattice Gauge Theory
The Svetitsky-Yaffe conjecture for finite temperature 4d SU(2) lattice gauge
theory is confirmed by observing matching of block spin effective actions of
the gauge model with those of the 3d Ising model. The effective action for the
gauge model is defined by blocking the signs of the Polyakov loops with the
majority rule. To compute it numerically, we apply a variant of the IMCRG
method of Gupta and Cordery.Comment: LaTeX2e, 22 pages, 8 Figure
Highly Sensitive Centrality Dependence of Elliptic Flow -- A Novel Signature of the Phase Transition in QCD
Elliptic flow of the hot, dense system which has been created in
nucleus-nucleus collisions develops as a response to the initial azimuthal
asymmetry of the reaction region. Here it is suggested that the magnitude of
this response shows a ``kinky'' dependence on the centrality of collisions for
which the system passes through a first-order or rapid transition between
quark-gluon plasma and hadronic matter. We have studied the system Pb(158AGeV)
on Pb employing a recent version of the transport theoretical approach RQMD and
find the conjecture confirmed. The novel phase transition signature may be
observable in present and forthcoming experiments at CERN-SPS and at RHIC, the
BNL collider.Comment: Version as published in PRL 82 (1999) 2048, title chang
Transverse QCD Dynamics Near the Light Cone
Starting from the QCD Hamiltonian in near-light cone coordinates, we study
the dynamics of the gluonic zero modes. Euclidean 2+1 dimensional lattice
simulations show that the gap at strong coupling vanishes at intermediate
coupling. This result opens the possibility to synchronize the continuum limit
with the approach to the light cone.Comment: 15 pages, LaTeX, 3 figures (7 PS files
Combining a root exclusion technique with continuous measurements of CO2 by chambers and inside soil for a pin-point separation of ecosystem respiration in croplands
To better assess ecosystem C budgets of croplands and understand their potential response to climate and management changes, detailed information on the mechanisms and environmental controls driving the individual C flux components are needed. This accounts in particular for the ecosystem respiration (Reco) and its components, the autotrophic (Ra) and heterotrophic respiration (Rh) which vary tremendously in time and space. Therefore, we developed and tested a method to separate Reco into Ra (as the sum of Ra (shoot) and Ra (root)) and Rh in order to detect temporal and small-scale spatial dynamics within their relative contribution to overall Reco. Investigations were carried out for winter wheat (Triticum aestivum) during the crop season 2015 at an experimental plot (CarboZALF-D) located in the hummocky ground moraine landscape of NE Germany. Reco was derived from CO2 flux measurements from plant stand and soil during nighttime using automatic chambers. Rh was derived from CO2 efflux measurements from fallow next to the automatic chambers using CO2 sampling tubes in 10 cm soil depth. Ra (root) was calculated as the difference between CO2 efflux measurements in planted soil and Rh. Ra (shoot) was calculated as Reco - Ra (root) - Rh. Reco varied seasonally from <1 to 9.5 g C m-2 d-1, and was higher in adult (a) and reproductive (r) than juvenile (j) stands (g C m-2 d-1: j 1.2, a 4.6, r 5.3). Observed Ra and Rh were in general smaller compared to the independently measured Reco, contributing in average 56 % and 44 % to Reco. However, both varied strongly regarding their environmental drivers and particular contribution throughout the study period, following the seasonal development of soil temperature and moisture (Rh) as well as crop development (Ra). Thus, our results consistently revealed temporal dynamics regarding the relative contribution of Ra (root) and Ra (shoot) to Ra, as well as of Ra and Rh to Reco. Based on the observed results, implications for partitioning of Reco in croplands are given, which requires a spatial and temporal pin-point approach to increase reliability
The Thermodynamics of Quarks and Gluons
This is an introduction to the study of strongly interacting matter. We
survey its different possible states and discuss the transition from hadronic
matter to a plasma of deconfined quarks and gluons. Following this, we
summarize the results provided by lattice QCD finite temperature and density,
and then investigate the nature of the deconfinement transition. Finally we
give a schematic overview of possible ways to study the properties of the
quark-gluon plasma.Comment: 19 pages, 21 figures; lecture given at the QGP Winter School,
Jaipur/India, Feb.1-3, 2008; to appear in Springer Lecture Notes in Physic
The Polarized H and D Atomic Beam Source for ANKE at COSY-J\"ulich
A polarized atomic beam source was developed for the polarized internal
storage-cell gas target at the magnet spectrometer ANKE of COSY-J\"ulich. The
intensities of the beams injected into the storage cell, measured with a
compression tube, are hydrogen atoms/s (two hyperfine
states) and deuterium atoms/s (three hyperfine states). For
the hydrogen beam the achieved vector polarizations are . For the deuterium beam, the obtained combinations of vector
and tensor () polarizations are (with a
constant ), and or (both with vanishing ). The paper includes a detailed
technical description of the apparatus and of the investigations performed
during the development.Comment: 18 pages, 26 figures, 4 table
Beating dark-dark solitons in Bose-Einstein condensates
Motivated by recent experimental results, we study beating dark-dark solitons
as a prototypical coherent structure that emerges in two-component
Bose-Einstein condensates. We showcase their connection to dark- bright
solitons via SO(2) rotation, and infer from it both their intrinsic beating
frequency and their frequency of oscillation inside a parabolic trap. We
identify them as exact periodic orbits in the Manakov limit of equal inter- and
intra-species nonlinearity strengths with and without the trap and showcase the
persistence of such states upon weak deviations from this limit. We also
consider large deviations from the Manakov limit illustrating that this
breathing state may be broken apart into dark-antidark soliton states. Finally,
we consider the dynamics and interactions of two beating dark-dark solitons in
the absence and in the presence of the trap, inferring their typically
repulsive interaction.Comment: 13 pages, 14 figure
Towards a Realistic Equation of State of Strongly Interacting Matter
We consider a relativistic strongly interacting Bose gas. The interaction is
manifested in the off-shellness of the equilibrium distribution. The equation
of state that we obtain for such a gas has the properties of a realistic
equation of state of strongly interacting matter, i.e., at low temperature it
agrees with the one suggested by Shuryak for hadronic matter, while at high
temperature it represents the equation of state of an ideal ultrarelativistic
Stefan-Boltzmann gas, implying a phase transition to an effectively weakly
interacting phase.Comment: LaTeX, figures not include
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