23,798 research outputs found
Slag ladle insulation
Slag from Pasminco's lead-zinc smelters, which is rich in zinc, is transferred in thirteen tonne capacity ladles from the blast furnace to the slag fuming furnace. The cycle time is about three hours. The Study Group was asked to examine whether heat could be conserved by some insulation strategy, without at any stage overheating the steel of the ladle
Quenched Chiral Perturbation Theory for Baryons
We develop quenched chiral perturbation theory for baryons using the
graded-symmetry formalism of Bernard and Golterman and calculate non-analytic
contributions to the baryon masses coming from quenched chiral loops. The usual
term proportional to is substantially altered due to the
cancellation of diagrams with internal quark loops. In addition, the
``hairpin'' vertex leads to a new correction, proportional to . We
compare our results to numerical lattice data and use them to estimate the size
of the quenching error in the octet baryon masses.Comment: 7 pages (An abridged version of this note will appear in the
proceedings of Lattice'93. Latex + 14 postscript files, bundled using
uufiles. Needs psfig.) UW/PT-93-0
Decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation
We study the decuplet baryon magnetic moments in a QCD-based quark model
beyond quenched approximation. Our approach for unquenching the theory is based
on the heavy baryon perturbation theory in which the axial couplings for baryon
- meson and the meson-meson-photon couplings from the chiral perturbation
theory are used together with the QM moment couplings. It also involves the
introduction of a form factor characterizing the structure of baryons
considered as composite particles. Using the parameters obtained from fitting
the octet baryon magnetic moments, we predict the decuplet baryon magnetic
moments. The magnetic moment is found to be in good agreement with
experiment: is predicted to be compared to the
experimental result of (2.02 0.05) .Comment: 19 pages, 2 figure
Development of high thermal conductivity polymeric materials for spacecraft use Final report, 1 Jul. 1966 - 31 May 1969
High thermal conductivity polymeric materials for spacecraft applications using phenyl compound
Regulation of transcription by the Arabidopsis UVR8 photoreceptor involves a specific histone modification
The photoreceptor UV RESISTANCE LOCUS 8 (UVR8) specifically mediates photomorphogenic responses to UV-B wavelengths. UVR8 acts by regulating transcription of a set of genes, but the underlying mechanisms are unknown. Previous research indicated that UVR8 can associate with chromatin, but the specificity and functional significance of this interaction are not clear. Here we show, by chromatin immunoprecipitation, that UV-B exposure of Arabidopsis increases acetylation of lysines K9 and/or K14 of histone H3 at UVR8-regulated gene loci in a UVR8-dependent manner. The transcription factors HY5 and/or HYH, which mediate UVR8-regulated transcription, are also required for this chromatin modification, at least for the ELIP1 gene. Furthermore, sequencing of the immunoprecipitated DNA revealed that all UV-B-induced enrichments in H3K9,14diacetylation across the genome are UVR8-dependent, and approximately 40 % of the enriched loci contain known UVR8-regulated genes. In addition, inhibition of histone acetylation by anacardic acid reduces the UV-B induced, UVR8 mediated expression of ELIP1 and CHS. No evidence was obtained in yeast 2-hybrid assays for a direct interaction between either UVR8 or HY5 and several proteins involved in light-regulated histone modification, nor for the involvement of these proteins in UVR8-mediated responses in plants, although functional redundancy between proteins could influence the results. In summary, this study shows that UVR8 regulates a specific chromatin modification associated with transcriptional regulation of a set of UVR8-target genes
Electromagnetic Moments of the Baryon Decuplet
We compute the leading contributions to the magnetic dipole and electric
quadrupole moments of the baryon decuplet in chiral perturbation theory. The
measured value for the magnetic moment of the is used to determine
the local counterterm for the magnetic moments. We compare the chiral
perturbation theory predictions for the magnetic moments of the decuplet with
those of the baryon octet and find reasonable agreement with the predictions of
the large-- limit of QCD. The leading contribution to the quadrupole
moment of the and other members of the decuplet comes from one--loop
graphs. The pionic contribution is shown to be proportional to (and so
will not contribute to the quadrupole moment of nuclei), while the
contribution from kaons has both isovector and isoscalar components. The chiral
logarithmic enhancement of both pion and kaon loops has a coefficient that
vanishes in the limit. The third allowed moment, the magnetic octupole,
is shown to be dominated by a local counterterm with corrections arising at two
loops. We briefly mention the strange counterparts of these moments.Comment: Uses harvmac.tex, 15 pages with 3 PostScript figures packed using
uufiles. UCSD/PTH 93-22, QUSTH-93-05, Duke-TH-93-5
Thermally conducting electron transfer polymers
New polymeric material exhibits excellent physical shock protection, high electrical resistance, and thermal conductivity. It is especially useful for electronic circuitry, such as subminiaturization of components and modular construction of circuits
Improved thermally conducting electron transfer polymers
Development of polymers with improved heat transfer coefficients for use in encapsulating electronic modules is discussed. Chemical reactions for synthesizing the polymers are described and thermodynamic and physical properties are analyzed
Supplement to MTI Study on Selective Passenger Screening in the Mass Transit Rail Environment, MTI Report 09-05
This supplement updates and adds to MTIs 2007 report on Selective Screening of Rail Passengers (Jenkins and Butterworth MTI 07-06: Selective Screening of Rail Passengers). The report reviews current screening programs implemented (or planned) by nine transit agencies, identifying best practices. The authors also discuss why three other transit agencies decided not to implement passenger screening at this time. The supplement reconfirms earlier conclusions that selective screening is a viable security option, but that effective screening must be based on clear policies and carefully managed to avoid perceptions of racial or ethnic profiling, and that screening must have public support. The supplement also addresses new developments, such as vapor-wake detection canines, continuing challenges, and areas of debate. Those interested should also read MTI S-09-01 Rail Passenger Selective Screening Summit
Electromagnetic Polarisability of the Nucleon in Chiral Perturbation Theory
We compute the polarisability of the nucleon to leading order in chiral
perturbation theory. The contributions from kaons and baryon resonances as
intermediate states are included in addition to the contribution from pions and
nucleons that had been previously computed. The isoscalar operators are
dominated by the infrared behaviour of pion loops giving rise to a
coefficient. In contrast, the isovector operators are dominated by loops
involving kaons, giving a coefficient, and further demonstrates that
the strange quark is an important component of the nucleon. In addition, the
inclusion of the decuplet of baryon resonances as intermediate states
substantially modifies the result found from the octet baryons alone for the
isoscalar polarisability.Comment: 11 pages (uses harvmac, figures available upon request) , UCSD/PTH
92-30, QUSTH-92-0
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