2,207 research outputs found
Reconsideration of the QCD corrections to the decays into light hadrons using the principle of maximum conformality
In the paper, we analyze the decays into light hadrons at the
next-to-leading order QCD corrections by applying the principle of maximum
conformality (PMC). The relativistic correction at the -order level has been included in the discussion, which gives about
contribution to the ratio . The PMC, which satisfies the renormalization
group invariance, is designed to obtain a scale-fixed and scheme-independent
prediction at any fixed order. To avoid the confusion of treating -terms,
we transform the usual pQCD series into the one under the
minimal momentum space subtraction scheme. To compare with the prediction under
conventional scale setting, , after applying the PMC, we obtain
, where the
errors are squared averages of the ones caused by and . The PMC prediction agrees with the recent PDG value within errors, i.e.
. Thus we think the mismatching
of the prediction under conventional scale-setting with the data is due to
improper choice of scale, which however can be solved by using the PMC.Comment: 5 pages, 2 figure
Understanding the internet topology evolution dynamics
The internet structure is extremely complex. The Positive-Feedback Preference
(PFP) model is a recently introduced internet topology generator. The model
uses two generic algorithms to replicate the evolution dynamics observed on the
internet historic data. The phenomenological model was originally designed to
match only two topology properties of the internet, i.e. the rich-club
connectivity and the exact form of degree distribution. Whereas numerical
evaluation has shown that the PFP model accurately reproduces a large set of
other nontrivial characteristics as well. This paper aims to investigate why
and how this generative model captures so many diverse properties of the
internet. Based on comprehensive simulation results, the paper presents a
detailed analysis on the exact origin of each of the topology properties
produced by the model. This work reveals how network evolution mechanisms
control the obtained topology properties and it also provides insights on
correlations between various structural characteristics of complex networks.Comment: 15 figure
Bis(4-acetyl-3-methyl-1-phenyl-1H-pyrazol-5-olato-κ2 O,O′)bis(N,N-dimethylformamide-κO)nickel(II)
The title complex, [Ni(C12H11N2O2)2(C3H7NO)2], lies on on an inversion center. The NiII ion is coordinated in a slightly distorted octahedral coordination enviroment by four O atoms from two bis-chelating 4-acety-3-methyl-1-phenyl-1H-pyrazol-5-olate ligands in the equatorial plane and two O atoms from two N,N-dimethylformamide ligands in the axial sites. In the crystal structure, weak intermolecular π–π stacking interactions with centroid–centroid distances of 3.7467 (13) Å link molecules into chains extending alongthe b axis
Structural and colored disruption as camouflage strategies in two sympatric Asian box turtle species (<i>Cuora</i> spp.)
Disruptive coloration is a common camouflage strategy that breaks body outlines and ostensibly blends into complex backgrounds. However, the contrasting false edge caused by the animal's structure can also break the outline, and there is no empirical evidence to support this strategy. Here, we examined the Gabor edge disruption ratio (GabRat) of two species with divergent carapaces, the keeled box turtle (Cuora mouhotii) and the Indochinese box turtle (C. galbinifrons), on preferred (e.g., deciduous leaves) and non-preferred (i.e., grass) substrates. We quantified edge disruption in different substrates to compare between-species differences in the GabRat of disruptive coloration among the turtles’ preferred and non-preferred (control) substrates. We found that both species exhibited higher GabRat on preferred substrates, but interestingly, the keeled box turtle, with a uniformly colored carapace containing flat scutes and two keels, had a higher GabRat than the Indochinese box turtle, characterized by two yellow stripes on its carapace. Our results indicated that the strong brightness gradients caused by the directional illumination of the flatted and keeled carapace creates disruptive coloration in the keeled box turtle, whereas a high chroma contrast creates disruptive coloration in the Indochinese box turtle. For these turtles, the structural modifications result in variations in brightness that lead to higher levels of disruption than the chromatic disruption of the Indochinese box turtle. Our study provides, to our knowledge, the first evidence of disruptive camouflage in turtles and the first comprehensive test of structural and colored disruption in vertebrates
Partial masquerading and background matching in two Asian box turtle species (<i>Cuora</i> spp.)
Animals living in heterogeneous natural environments adopt different camouflage strategies against different backgrounds, and behavioral adaptation is crucial for their survival. However, studies of camouflage strategies have not always quantified the effect of multiple strategies used together. In the present study, we used a human visual model to quantify similarities in color and shape between the carapace patterns of two Cuora species and their preferred habitats. Our results showed that the color of the middle stripe on the carapace of Cuora galbinifrons (Indochinese box turtle) was significantly similar to the color of their preferred substrates. Meanwhile, the middle stripe on the carapace of C. mouhotii (keeled box turtle) contrasted more with their preferred substrates, and the side stripe matched most closely with the environment. Furthermore, the carapace side stripe of C. galbinifrons and the carapace middle stripe of C. mouhotii highly contrasted with their preferred substrates. We quantified the similarity in shape between the high-contrast stripes of both Cuora species and leaves from their habitats. The carapace middle stripe of C. mouhotii was most similar in shape to leaves from the broad-leaves substrate, and the carapace side stripe of C. galbinifrons was the most similar in shape to leaves from the bamboo-leaves substrate. We determined that these species adopt partial masquerading when their entire carapace is exposed and partially match their background when they semi-cover themselves in leaf litter. To the best of our knowledge, this is the first study to demonstrate that partial masquerading and background matching improve the camouflage effect of Asian box turtles in their preferred habitats. This is a novel study focusing on the influence of the shape and color of individual carapace segments on reducing detectability and recognition.</p
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