531 research outputs found
Accretion and outflow activity on the late phases of pre-main-sequence evolution. The case of RZ Piscium
RZ Psc is an isolated high-latitude post-T Tauri star that demonstrates a UX
Ori-type photometric activity. The star shows very weak spectroscopic
signatures of accretion, but at the same time possesses the unusual footprints
of the wind in Na I D lines. In the present work we investigate new
spectroscopic observations of RZ Psc obtained in 2014 during two observation
runs. We found variable blueshifted absorption components (BACs) in lines of
the other alcali metals, K I 7699 \AA\ and Ca II IR triplet. We also confirmed
the presence of a weak emission component in the H line, which allowed
us to estimate the mass accretion rate on the star as Msun yr. We could not reveal any clear periodicity in the
appearance of BACs in sodium lines. Nevertheless, the exact coincidence of the
structure and velocities of the Na I D absorptions observed with the interval
of about one year suggests that such a periodicity should exist
Stability and flow fields structure for interfacial dynamics with interfacial mass flux
We analyze from a far field the evolution of an interface that separates
ideal incompressible fluids of different densities and has an interfacial mass
flux. We develop and apply the general matrix method to rigorously solve the
boundary value problem involving the governing equations in the fluid bulk and
the boundary conditions at the interface and at the outside boundaries of the
domain. We find the fundamental solutions for the linearized system of
equations, and analyze the interplay of interface stability with flow fields
structure, by directly linking rigorous mathematical attributes to physical
observables. New mechanisms are identified of the interface stabilization and
destabilization. We find that interfacial dynamics is stable when it conserves
the fluxes of mass, momentum and energy. The stabilization is due to inertial
effects causing small oscillations of the interface velocity. In the classic
Landau dynamics, the postulate of perfect constancy of the interface velocity
leads to the development of the Landau-Darrieus instability. This
destabilization is also associated with the imbalance of the perturbed energy
at the interface, in full consistency with the classic results. We identify
extreme sensitivity of the interface dynamics to the interfacial boundary
conditions, including formal properties of fundamental solutions and
qualitative and quantitative properties of the flow fields. This provides new
opportunities for studies, diagnostics, and control of multiphase flows in a
broad range of processes in nature and technology
On the search for 50 GeV neutrinos
Using the computer code CompHEP we estimate the number of events and the
background, at LEP II and TESLA, for the reaction ,
where is a hypothetical Dirac neutrino with mass of the order of 50 GeV.Comment: Standard LaTeX, 9 pages, 2 tables, 3 figure
Precision measurements, extra generations and heavy neutrino
The existence of extra chiral generations with all fermions heavier than
is strongly disfavored by the precision electroweak data. The exclusion
of one additional generation of heavy fermions in SUSY extension of Standard
Model is less forbidden if chargino and neutralino have low degenerate masses
with GeV. However the data are fitted nicely even by a few
extra generations, if one allows neutral leptons to have masses close to 50
GeV. Such heavy neutrino can be searched in the reaction at LEP-200 with total final luminosity of .Comment: 5 pages, 6 figures, Proceedings ICHEP2000 Osaka conferenc
Search for Higgs Boson at LHC in the Reaction pp->gamma+gamma+jet at a Low Luminosity
We discuss the SM Higgs discovery potential of the LHC in the channel
pp->H+jet->gamma+gamma+jet when the jet is observed at sufficiently high Pt and
a small rapidity to be reliably identified. We calculate all the signal
subprocesses and the irreducible background with realistic kinematical cuts.
The reducible QCD background is also estimated. We conclude that the channel
gamma+gamma+jet can give about 120-200 signal events for Higgs mass MH=100-140
GeV at the integrated luminosity of 30 inverse fb. This signal rate should be
compared with only 330-600 events for the irreducible background per two-photon
invariant mass interval of 2 GeV. We estimate the QCD reducible background at
the level of 20% of the irreducible one. Thus, one may hope that the Higgs
boson can be discovered already during the LHC operation at a low luminosity.
At a high luminosity the observation of several hundreds of high Pt Higgs
bosons in this channel will be possible with significance higher than 15 for
L=100 inverse fb.Comment: 21 pages (LaTeX code, epsf.sty), 2 tables, 9 figures; to appear in
the Proceedings of XIIth International Workshop on High Energy Physics and
Quantum Field Theory (QFTHEP-97), Samara, Russia, September 4-10, 199
Sociology, labour and transition in post-Soviet Russia: A view from within
For almost 20 years, since the early 1990s, Professor Simon Clarke led multiple international research projects in Russia, China and Vietnam studying labour relations, enterprise restructuring and household economics under post-socialist transition. Breaking out of post-socialist scholarship’s narrow confines, both social and ideological, he led an exploration of the void opened by former Soviet Union disintegration reconnecting with those who brought the brunt of it. Equally unique among western scholars was his promotion of a vast network of former Soviet Union researchers and activists, later formalised in the Institute for Comparative Research in Labour Relations. Here, for the first time, some of its leading scholars reflect on his legacy, methods and ever-lasting contribution to the advancement of sociology and social activism in Russia. Their accounts convey the radically alternative character of the overall project, returning both achievements and limitations. In substantive terms, the emerging picture confirms the indeterminacy and complexity of Clarke’s original findings: no linear development from ‘the subsumption of labour under capital’ to ‘familiar patterns of class conflict’ has occurred. Instead, growing labour protests follow labour degradation and restructuring, a strong state becoming the arbiter in the stand-off between neoliberalism and workers’ resistance
Raman spectroscopic techniques for meat analysis: A review
Raman spectroscopy (vibrational spectroscopy) proved to be an effective analytical approach in the field of geology, semiconductors, materials and polymers. Over the past decade, Raman spectroscopy has attracted the attention of researchers as a non-destructive, highly sensitive, fast and eco-friendly method and has demonstrated the unique capabilities of food analysis. The use of Raman spectroscopic methods (RSMs) to assess the quality of meat and finished products is rapidly expanding. From the analysis of one sample, you can get a large amount of information about the structure of proteins, the composition of fatty acids, organoleptic parameters, autolysis and spoilage indicators, authentication of raw materials, technological properties. An important advantage of the method is the comparability of the results obtained with the data of traditional analytical methods. Traditional methods of determining the quality of meat are often time-consuming, expensive and lead to irreversible damage to a sample. It is difficult to use them in production conditions directly on the meat processing lines. Technological advances have made it possible to develop portable Raman spectroscopes to use directly in production. The article presents the basic principles of Raman spectroscopy, system atizes the results of the use of RSMs for the analysis of meat quality from different types of slaughter animals and provides tools for analyzing the data of the obtained spectra. Raman spectra have many dependent variables, so chemometric assays are used to work with them. Literature analysis has shown that currently there is no unified database of meat spectra in the world, standardized protocols for conducting research and processing the obtained results. In Russia, the use of RSMs is a new,Raman spectroscopy (vibrational spectroscopy) proved to be an effective analytical approach in the field of geology, semiconductors, materials and polymers. Over the past decade, Raman spectroscopy has attracted the attention of researchers as a non-destructive, highly sensitive, fast and eco-friendly method and has demonstrated the unique capabilities of food analysis. The use of Raman spectroscopic methods (RSMs) to assess the quality of meat and finished products is rapidly expanding. From the analysis of one sample, you can get a large amount of information about the structure of proteins, the composition of fatty acids, organoleptic parameters, autolysis and spoilage indicators, authentication of raw materials, technological properties. An important advantage of the method is the comparability of the results obtained with the data of traditional analytical methods. Traditional methods of determining the quality of meat are often time-consuming, expensive and lead to irreversible damage to a sample. It is difficult to use them in production conditions directly on the meat processing lines. Technological advances have made it possible to develop portable Raman spectroscopes to use directly in production. The article presents the basic principles of Raman spectroscopy, system atizes the results of the use of RSMs for the analysis of meat quality from different types of slaughter animals and provides tools for analyzing the data of the obtained spectra. Raman spectra have many dependent variables, so chemometric assays are used to work with them. Literature analysis has shown that currently there is no unified database of meat spectra in the world, standardized protocols for conducting research and processing the obtained results. In Russia, the use of RSMs is a new, promising and relevant area of research in the field of meat quality
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