42,141 research outputs found
Further experimental tests for simple relations between unpolarized and polarized quark parton distributions
Some simple relations between unpolarized and polarized quark parton
distributions have direct experimental consequences which will be presented
here. In particular, we will see that it is possible to relate the deep
inelastic structure functions and , both for proton and deuteron, in
fair agreement with experimental data.Comment: 5 pages, in Latex, 3 figure
A Review and Outlook for the Removal of Radon-Generated Po-210 Surface Contamination
The next generation low-background detectors operating deep underground aim
for unprecedented low levels of radioactive backgrounds. The deposition and
presence of radon progeny on detector surfaces is an added source of energetic
background events. In addition to limiting the detector material's radon
exposure in order to reduce potential surface backgrounds, it is just as
important to clean surfaces to remove inevitable contamination. Such studies of
radon progeny removal have generally found that a form of etching is effective
at removing some of the progeny (Bi and Pb), however more aggressive
techniques, including electropolishing, have been shown to effectively remove
the Po atoms. In the absence of an aggressive etch, a significant fraction of
the Po atoms are believed to either remain behind within the surface or
redeposit from the etching solution back onto the surface. We explore the
chemical nature of the aqueous Po ions and the effect of the oxidation state of
Po to maximize the Po ions remaining in the etching solution of contaminated Cu
surfaces. We present a review of the previous studies of surface radon progeny
removal and our findings on the role of oxidizing agents and a cell potential
in the preparation of a clean etching technique.Comment: Proceedings of the Low Radioactivity Techniques (LRT) 2017, Seoul,
South Korea, May 24-26, 201
Dissipative hydrodynamics in 2+1 dimension
In 2+1 dimension, we have simulated the hydrodynamic evolution of QGP fluid
with dissipation due to shear viscosity. Comparison of evolution of ideal and
viscous fluid, both initialised under the same conditions e.g. same
equilibration time, energy density and velocity profile, reveal that the
dissipative fluid evolves slowly, cooling at a slower rate. Cooling get still
slower for higher viscosity. The fluid velocities on the otherhand evolve
faster in a dissipative fluid than in an ideal fluid. The transverse expansion
is also enhanced in dissipative evolution. For the same decoupling temperature,
freeze-out surface for a dissipative fluid is more extended than an ideal
fluid. Dissipation produces entropy as a result of which particle production is
increased. Particle production is increased due to (i) extension of the
freeze-out surface and (ii) change of the equilibrium distribution function to
a non-equilibrium one, the last effect being prominent at large transverse
momentum. Compared to ideal fluid, transverse momentum distribution of pion
production is considerably enhanced. Enhancement is more at high than at
low . Pion production also increases with viscosity, larger the viscosity,
more is the pion production. Dissipation also modifies the elliptic flow.
Elliptic flow is reduced in viscous dynamics. Also, contrary to ideal dynamics
where elliptic flow continues to increase with transverse momentum, in viscous
dynamics, elliptic flow tends to saturate at large transverse momentum. The
analysis suggest that initial conditions of the hot, dense matter produced in
Au+Au collisions at RHIC, as extracted from ideal fluid analysis can be changed
significantly if the QGP fluid is viscous.Comment: 11 pages, 10 figures (revised). In the revised version, calculations
are redone with ADS/CFT and perurbative estimate of viscosity. Comments on
the unphysical effects like early reheating of the fluid, in 1st order
dissipative theories are added. The particle spectra calculations are redone
with modified programm
Interleukin 2 restores CD3-zeta chain expression but fails to generate tumour-specific lytic activity in tumour-infiltrating lymphocytes derived from human colorectal hepatic metastases.
Metastatic colorectal cancer is usually progressive despite infiltration of the tumours by T lymphocytes, suggesting that these tumour-infiltrating lymphocytes (TILs) are functionally deficient. Recently, TILs from other tumours have been shown to express reduced levels of the T-cell receptor signal-transducing CD3-zeta chain. We were interested to determine whether a similar abnormality existed in TILs from human colorectal hepatic metastasis (CHM) and, if so, whether correcting the abnormality in vitro would restore anti-tumour activity and provide support for the development of immunotherapy for colorectal hepatic metastases. Twelve of 19 TILs from colorectal hepatic metastases were successfully expanded in vitro in high-dose recombinant interleukin 2 (rlL-2) and their specific anti-tumour cytolytic activity was determined. CD3-positive (CD3+) TILs were HLA-Drhigh and CD69high, suggesting that they had been activated by exposure to antigen but expressed low levels of CD25, CD71 and the nuclear proliferation antigen Ki-67. Furthermore, they showed reduced expression of CD3-zeta compared with autologous peripheral blood T cells (PBTs) and failed to proliferate in the absence of high-dose rIL-2. Expansion of TILs in rIL-2 resulted in restoration of CD3-zeta expression and the ability to lyse K562 and Daudi cells but not autologous tumour cells. The absence of autologous tumour-specific cytolytic T-cell (CTL) activity may be due to the poor immunogenicity of colorectal tumour cells, which we found expressed only low levels of MHC I antigens and CD54 and failed to express MHC II antigens or the co-stimulatory molecules CD80, CD86 or CD106. The inability of rIL-2 to generate tumour-specific CTLs despite restoration of CD3-zeta expression and the presence of an intact lytic mechanism suggests that successful immunotherapy may require the development of strategies to increase the immunogenicity of this tumour
Stopping and Baryon Transport in Heavy Ion Reactions
In this report I will give an experimental overview on nuclear stopping in
hadron collisions, and relate observations to understanding of baryon
transport. Baryon number transport is not only evidenced via net-proton
distributions but also by the enhancement of strange baryons near mid-rapidity.
Although the focus is on high-energy data obtained from pp and heavy ions from
RHIC, relevant data from SPS and ISR will be considered. A discussion how the
available data at higher energy relates and gives information on baryon
junction, quark-diquark breaking will be made.Comment: 8 pages, 7 figures. Invited plenary talk for the 5'th international
conference on Physics and Astrophysics of Quark Gluon Plasma, February 8-12,
2005, Salt Lake City, Kolkata, Indi
Key barriers to community cohesion: views from residents of 20 London deprived neighbourhoods
The notion of community has been central to the political project of renewal of New Labour in the UK. The paper explores how the discourses of community are framed within New Labour and discusses these in the light of the results from research which focuses on how people within urban deprived areas construct their community. It draws upon the results of one part of a larger research project (the ‘Well London’ programme) which aimed to capture the views of residents from 20 disadvantaged neighbourhoods throughout London using an innovative qualitative method known as the ‘World Café’. Our results show the centrality of young people to the development of cohesive communities, the importance of building informal relationships between residents alongside encouraging greater participation to policy making, and the need to see these places as fragile and temporary locations but with considerable social strengths. Government policies are only partially addressing these issues. They pay greater attention to formally encouraging citizens to become more involved in policy making, largely ignore the contribution young people could make to the community cohesion agenda, and weakly define the shared norms and values that are crucial in building cohesive communities. Thus, the conclusion is that whilst an emphasis of the government on ‘community’ is to be welcome, more needs to be done in terms of considering the ‘voices’ of the community as well as enabling communities to determine and act upon their priorities
Simultaneous Kummer congruences and -orientations of KO and tmf
Building on results of M. Ando, M.J. Hopkins and C. Rezk, we show the
existence of uncountably many -String orientations of real
K-theory KO and of topological modular forms tmf, generalizing the -
(resp. the Witten) genus. Furthermore, the obstruction to lifting an
-String orientations from KO to tmf is identified with a
classical Iwasawa-theoretic condition. The common key to all these results is a
precise understanding of the classical Kummer congruences, imposed for all
primes simultaneously. This result is of independent arithmetic interest.Comment: final versio
Applications of Laser Microprobe Mass Analysis for Characterization of Asbestos
Laser microprobe mass analysis with the commercial LAMMA-500 (transmission type) instrument when utilized in laser desorption conditions provides information which allows the identification of particular asbestos varieties, in various types of samples, including lung tissue. Also it has detection capability of adsorbed organic material and it is a valuable tool for the study of the surface of chemically modified asbestos fibers manufactured by silanation or through phosgene treatment (chrysophosphate). Recent progress within our laboratory is discussed, and shortcomings of the methodology are indicated
The Surface Characterization of Modified Chrysotile Asbestos
In this paper, results of a semi-quantitative and qualitative leaching study of chrysotile and Chrysophosphate® fibers in oxalic acid and succinate salt buffer solutions with laser microprobe mass analysis (LAMMA) and electron probe X-ray micro-analysis (EPXMA) are presented, which demonstrate clearly the potential of these sensitive surface analytical tools for the analysis of natural physico-chemically modified and depleted fibers. These results are verified with those obtained by atomic absorption spectroscopy (AAS) for the measurement of the leached magnesium and iron concentration in solution. In order to study differences in adsorption behaviour and reaction capability between natural and chemically modified chrysotile, LAMMA-analysis was performed on fibers treated with benzo[a]pyrene, N,N-dimethylaniline (DMA) and ortho-phenylene-diamine (OPDA). In correlation with biomedical investigations. this study could contribute to the elucidation of the potential sequences of fiber surface properties in relation to the biological activity and cytotoxicity
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