1,063 research outputs found
Renormalization of four-fermion operators for higher twist calculations
The evaluation of the higher twist contributions to Deep Inelastic Scattering
amplitudes involves a non trivial choice of operator bases for the higher
orders of the OPE expansion of the two hadronic currents. In this talk we
discuss the perturbative renormalization of the four-fermion operators that
appear in the above bases.Comment: LATTICE98(matrixelement), 3 page
Higher-twist contributions to the Structure Functions coming from 4-fermion operators
We evaluate the contribution of a class of higher-twist operators to the
lowest moment of the Structure Functions, by computing appropriate matrix
elements of six four-fermion operators in the quenched approximation. Their
perturbative renormalization constants and mixing coefficients are calculated
in the 't Hooft-Veltman scheme of dimensional regularization, using codes
written in the algebraic manipulation computer language FORM.Comment: Talk presented at LATTICE99(matrix elements), Pisa (Italy), June 29 -
July 3; 3 pages; to be published in Nucl. Phys. B (Proc. Suppl.
Dynamics of Bulk vs. Nanoscale WS_2: Local Strain and Charging Effects
We measured the infrared vibrational properties of bulk and nanoparticle
WS in order to investigate the structure-property relations in these novel
materials. In addition to the symmetry-breaking effects of local strain,
nanoparticle curvature modifies the local charging environment of the bulk
material. Performing a charge analysis on the \emph{xy}-polarized E
vibrational mode, we find an approximate 1.5:1 intralayer charge difference
between the layered 2H material and inorganic fullerene-like (IF)
nanoparticles. This effective charge difference may impact the solid-state
lubrication properties of nanoscale metal dichalcogenides.Comment: 6 pages, 5 figure
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Soft topographic map for clustering and classification of bacteria
In this work a new method for clustering and building a
topographic representation of a bacteria taxonomy is presented. The method is based on the analysis of stable parts of the genome, the so-called âhousekeeping genesâ. The proposed method generates topographic maps of the bacteria taxonomy, where relations among different
type strains can be visually inspected and verified. Two well known DNA alignement algorithms are applied to the genomic sequences. Topographic maps are optimized to represent the similarity among the sequences according to their evolutionary distances. The experimental analysis is carried out on 147 type strains of the Gammaprotebacteria
class by means of the 16S rRNA housekeeping gene. Complete sequences of the gene have been retrieved from the NCBI public database. In the experimental tests the maps show clusters of homologous type strains and present some singular cases potentially due to incorrect classification
or erroneous annotations in the database
Independent beta-arrestin 2 and G protein-mediated pathways for angiotensin II activation of extracellular signal-regulated kinases 1 and 2.
Stimulation of a mutant angiotensin type 1A receptor (DRY/AAY) with angiotensin II (Ang II) or of a wild-type receptor with an Ang II analog ([sarcosine1,Ile4,Ile8]Ang II) fails to activate classical heterotrimeric G protein signaling but does lead to recruitment of beta-arrestin 2-GFP and activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) (maximum stimulation approximately 50% of wild type). This G protein-independent activation of mitogen-activated protein kinase is abolished by depletion of cellular beta-arrestin 2 but is unaffected by the PKC inhibitor Ro-31-8425. In parallel, stimulation of the wild-type angiotensin type 1A receptor with Ang II robustly stimulates ERK1/2 activation with approximately 60% of the response blocked by the PKC inhibitor (G protein dependent) and the rest of the response blocked by depletion of cellular beta-arrestin 2 by small interfering RNA (beta-arrestin dependent). These findings imply the existence of independent G protein- and beta-arrestin 2-mediated pathways leading to ERK1/2 activation and the existence of distinct "active" conformations of a seven-membrane-spanning receptor coupled to each
An assessment framework for REDD+ benefit sharing mechanisms within a forest policy mix
Policy instruments for implementing the Reducing Emissions from Deforestation
and Forest Degradation and the enhancement of forest carbon stocks (REDD+)
mechanism operate within an orchestra of national contexts and policy mixes
that affect the forest and other land sectors. How will policymakers choose
between the myriad of options for distributing REDD+ benefits, and be able to
evaluate its potential effectiveness, efficiency and equity (3Es) within the
various institutional and governance structures a where such a REDD+ benefit
sharing mechanism is situated? This is a pressing issue given the results-
based aspect of REDD+. We present here a three-element assessment framework
for evaluating outcomes and performance of REDD+ benefit sharing mechanisms,
using the criteria of effectiveness, efficiency and equity: (1) the structures
(objective and policies) of a REDD+ benefit sharing mechanism; (2) the broader
institutional and policy contexts underlying forest governance; and (3)
outcomes of REDD+ including emissions reductions, ecosystem service provision
and poverty alleviation. A strength of the assessment framework is its
flexible design to incorporate indicators relevant to different contexts; this
helps to generate a shared working understanding of what is to be evaluated in
the different REDD+ benefit sharing mechanisms (BSMs) across complex socio-
political contexts. In applying the framework to case studies, the assessment
highlights trade-offs among the 3Es, and the need to better manage access to
information, monitoring and evaluation, consideration of local perceptions of
equity and inclusive decision-making processes. The framework aims not to
simplify complexity but rather, serves to identify actionable ways forward
towards a more efficient, effective and equitable implementation and re-
evaluation of REDD+ BSMs as part of reflexive policymaking
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Hydrogeologic controls on ground-water and contaminant discharge to the Columbia River near the Hanford Townsite
The purpose of this study is to quantify ground-water and contaminant discharge to the Columbia River in the Hanford Townsite vicinity. The primary objectives of the work are to: describe the hydrogeologic setting and controls on ground-water movement and contaminant discharge to the Columbia River; understand the river/aquifer relationship and its effects on contaminant discharge to the Columbia River; quantify the ground-water and contaminant mass discharge to the Columbia River; and provide data that may be useful for a three-dimensional model of ground-water flow and contaminant transport in the Hanford Townsite study area. The majority of ground-water contamination occurs within the unconfined aquifer; therefore, ground-water and contaminant discharge from the unconfined aquifer is the emphasis of this study. The period of study is primarily from June 1990 through March 1992
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