The
Fortran package QCD-
Pegasus is presented. This program provides fast, flexible and accurate solutions of the evolution equations for unpolarized and polarized parton distributions of hadrons in ...perturbative QCD. The evolution is performed using the symbolic moment-space solutions on a one-fits-all Mellin inversion contour. User options include the order of the evolution including the next-to-next-to-leading order in the unpolarized case, the type of the evolution including an emulation of brute-force solutions, the evolution with a fixed number
n
f
of flavors or in the variable-
n
f
scheme, and the evolution with a renormalization scale unequal to the factorization scale. The initial distributions are needed in a form facilitating the computation of the complex Mellin moments.
Title of program: QCD-
Pegasus
Version: 1.0
Catalogue identifier: ADVN
Program summary URL:
http://cpc.cs.qub.ac.uk/summaries/ADVN
Program obtainable from: CPC Program Library Queen's University of Belfast, N. Ireland
License: GNU Public License
Computers: all
Operating systems: all
Program language:
Fortran 77 (using the common compiler extension of procedure names with more than six characters)
Memory required to execute: negligible (
<
1
MB
)
Other programs called: none
External files needed: none
Number of lines in distributed program, including test data, etc.: 8157
Number of bytes in distributed program, including test data, etc.: 240 578
Distribution format: tar.gz
Nature of the physical problem: Solution of the evolution equations for the unpolarized and polarized parton distributions of hadrons at leading order (LO), next-to-leading order and next-to-next-to-leading order of perturbative QCD. Evolution performed either with a fixed number
n
f
of effectively massless quark flavors or in the variable-
n
f
scheme. The calculation of observables from the parton distributions is not part of the present package.
Method of solution: Analytic solution in Mellin space (beyond LO in general by power-expansion around the lowest-order expansion) followed by a fast Mellin inversion to
x-space using a fixed one-fits-all contour.
Restrictions on complexity of the problem: The initial distributions for the evolution are required in a form facilitating an efficient calculation of their complex Mellin moments. The ratio of the renormalization and factorization scales
μ
r
/
μ
has to be a fixed number.
Typical running time: One to ten seconds, on a PC with a 2.0 GHz Pentium-IV processor, for performing the evolution of 200 initial distributions to 500
(
x
,
μ
)
points each. For more details see Section 6.
Lives in Transitchronicles the dangerous journeys of Central American migrants in transit through Mexico. Drawing on fieldwork in humanitarian aid shelters and other key sites, Wendy A. Vogt examines ...the multiple forms of violence that migrants experience as their bodies, labor, and lives become implicated in global and local economies that profit from their mobility as racialized and gendered others. She also reveals new forms of intimacy, solidarity, and activism that have emerged along transit routes over the past decade. Through the stories of migrants, shelter workers, and local residents, Vogt encourages us to reimagine transit as a site of both violence and precarity as well as social struggle and resistance.
Acute pain and emotion are processed in two forebrain networks, and the cingulate cortex is involved in both. Although Brodmann's cingulate gyrus had two divisions and was not based on any functional ...criteria, functional imaging studies still use this model. However, recent cytoarchitectural studies of the cingulate gyrus support a four-region model, with subregions, that is based on connections and qualitatively unique functions. Although the activity evoked by pain and emotion has been widely reported, some view them as emergent products of the brain rather than of small aggregates of neurons. Here, we assess pain and emotion in each cingulate subregion, and assess whether pain is co-localized with negative affect. Amazingly, these activation patterns do not simply overlap.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Human posterior cingulate cortex (PCC) and retrosplenial cortex (RSC) form the posterior cingulate gyrus, however, monkey connection and human imaging studies suggest that PCC area 23 is not uniform ...and atlases mislocate RSC. We histologically assessed these regions in 6 postmortem cases, plotted a flat map, and characterized differences in dorsal (d) and ventral (v) area 23. Subsequently, functional connectivity of histologically guided regions of interest (ROI) were assessed in 163
18Ffluorodeoxyglucose human cases with PET. Compared to area d23, area v23 had a higher density and larger pyramids in layers II, IIIc, and Vb and more intermediate neurofilament-expressing neurons in layer Va. Coregisrtration of each case to standard coordinates showed that the ventral branch of the splenial sulci coincided with the border between d/v PCC at −5.4 ± 0.17 cm from the vertical plane and +1.97 ± 0.08 cm from the bi-commissural line. Correlation analysis of glucose metabolism using histologically guided ROIs suggested important circuit differences including dorsal and ventral visual stream inputs, interactions between the vPCC and subgenual cingulate cortex, and preferential relations between dPCC and the cingulate motor region. The RSC, in contrast, had restricted correlated activity with pericallosal cortex and thalamus. Visual information may be processed with an orbitofrontal link for synthesis of signals to drive premotor activity through dPCC. Review of the literature in terms of a PCC duality suggests that interactions of dPCC, including area 23d, orient the body in space via the cingulate motor areas, while vPCC interacts with subgenual cortex to process self-relevant emotional and non-emotional information and objects and self-reflection.
Building on the model by Perdue, Long, and Allen, this study examined residents’ attitudes toward existing and future tourism development in several rural areas at different stages of tourism and ...economic development. Social exchange theory and destination life cycle model were used to examine the impacts of tourism development on residents’ attitudes when considered in conjunction with a community’s total economic activity. New social predictors and endogenous factors were tested in the model. Overall, residents of three distinct rural county-level areas were supportive of tourism development, and little evidence was found that suggests that attitudes toward tourism become negative with higher levels of tourism. After considering the level of tourism development in conjunction with the total economic activity, residents of the three county-level areas showed some signs of destination life cycle influencing their own relationship with tourism.
We present a new method for inferring the metallicity (Z) and ionization parameter (q) of H II regions and star-forming galaxies using strong nebular emission lines (SELs). We use Bayesian inference ...to derive the joint and marginalized posterior probability density functions for Z and q given a set of observed line fluxes and an input photoionization model. Our approach allows the use of arbitrary sets of SELs and the inclusion of flux upper limits. The method provides a self-consistent way of determining the physical conditions of ionized nebulae that is not tied to the arbitrary choice of a particular SEL diagnostic and uses all the available information. Unlike theoretically calibrated SEL diagnostics, the method is flexible and not tied to a particular photoionization model. We describe our algorithm, validate it against other methods, and present a tool that implements it called IZI. Using a sample of nearby extragalactic H II regions, we assess the performance of commonly used SEL abundance diagnostics. We also use a sample of 22 local H II regions having both direct and recombination line (RL) oxygen abundance measurements in the literature to study discrepancies in the abundance scale between different methods. We find that oxygen abundances derived through Bayesian inference using currently available photoionization models in the literature can be in good (~30%) agreement with RL abundances, although some models perform significantly better than others. We also confirm that abundances measured using the direct method are typically ~0.2 dex lower than both RL and photoionization-model-based abundances.
We report the discovery of optical emission from the nonradiative shocked ejecta of three young type Ia supernova remnants (SNRs): SNR 0519-69.0, SNR 0509-67.5, and N103B. Deep integral field ...spectroscopic observations reveal broad and spatially resolved Fe XIV 5303 Å emission. The width of the broad line reveals, for the first time, the reverse shock speeds. For two of the remnants we can constrain the underlying supernova explosions with evolutionary models. SNR 0519-69.0 is well explained by a standard near-Chandrasekhar mass explosion, whereas for SNR 0509-67.5 our analysis suggests an energetic sub-Chandrasekhar mass explosion. With S XII, Fe IX, and Fe XV also detected, we can uniquely visualize different layers of the explosion. We refer to this new analysis technique as "supernova remnant tomography".
We have derived the coefficients of the highest three1/
x
-enhanced small-
x
logarithms of all timelike splitting functions and the coefficient functions for the transverse fragmentation function in ...one-particle inclusive
e
+
e
−
annihilation at (in principle) all orders in massless perturbative QCD. For the longitudinal fragmentation function we present the respective two highest contributions. These results have been obtained from KLN-related decompositions of the unfactorized fragmentation functions in dimensional regularization and their structure imposed by the mass-factorization theorem. The resummation is found to completely remove the huge small-
x
spikes present in the fixed-order results, allowing for stable results down to very small values of the momentum fraction and scaling variable
x
. Our calculations can be extended to (at least) the corresponding
α
s
n
ln
2
n
−ℓ
x
contributions to the above quantities and their counterparts in deep-inelastic scattering.
The Mann–Kendall test associated with the Sen's slope is a very widely used non-parametric method for trend analysis. It requires serially uncorrelated
time series, yet most of the atmospheric ...processes exhibit positive
autocorrelation. Several prewhitening methods have therefore been designed
to overcome the presence of lag-1 autocorrelation. These include a
prewhitening, a detrending and/or a correction of the detrended slope and
the original variance of the time series. The choice of which prewhitening
method and temporal segmentation to apply has consequences for the
statistical significance, the value of the slope and of the confidence limits. Here, the effects of various prewhitening methods are analyzed for
seven time series comprising in situ aerosol measurements (scattering coefficient, absorption coefficient, number concentration and aerosol
optical depth), Raman lidar water vapor mixing ratio,
as well as tropopause and zero-degree temperature levels measured by radio-sounding. These time series are characterized by a broad variety of distributions, ranges and lag-1
autocorrelation values and vary in length between 10 and 60 years. A common
way to work around the autocorrelation problem is to decrease it by
averaging the data over longer time intervals than in the original time
series. Thus, the second focus of this study evaluates the effect of time
granularity on long-term trend analysis. Finally, a new algorithm involving
three prewhitening methods is proposed in order to maximize the power of the test, to minimize the number of erroneous detected trends in the absence of a real trend and to ensure the best slope estimate for the considered length of the time series.
We have computed the contributions of the quartic Casimir invariants to the four-loop anomalous dimensions of twist-2 spin-N operators at N≤16. The results provide new information on the structure of ...the next-to-next-to-next-to-leading order (N3LO) splitting functions Pik(3)(x) for the evolution of parton distributions, and facilitate approximate expressions which include the quartic-Casimir contributions to the (light-like) gluon cusp anomalous dimension. These quantities turn out to be closely related, by a generalization of the lower-order ‘Casimir scaling’, to the corresponding quark results. Using these findings, we present an approximate result for the four-loop gluon cusp anomalous dimension in QCD which is sufficient for phenomenological applications.
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