Long-distance Scale Research Articles

Molecular Nature of X(3872) in B 0 → K 0 X(3872) and B + K + X(3872) Decays

We investigate the decays of B 0 → K 0 X(3872) and B + → K + X(3872) based on the picture where the X(3872) resonance is strongly coupled to the channel. In addition to the decay mechanism where the X(3872) resonance is formed from the pair hadronization with the short-distance interaction, we have also considered the rescattering diagrams in the long-distance scale, where D and are formed from c and separately. Because of the difference of the mass thresholds of charged and neutral channels, and the rather narrow width of the X(3872) resonance, at the X(3872) mass, the loop functions of and are much different. Taking this difference into account, the ratio of can be naturally obtained. Based on this result, we also evaluate the decay widths of . It is expected that future experimental measurements of these decays can be used to elucidate the nature of the X(3872) resonance.

Unsupervised Segmentation-Based Machine Learning as an Advanced Analysis Tool for Single Molecule Break Junction Data

Improved understanding of charge-transport in single molecules is essential for harnessing the potential of molecules e.g. as circuit components at the ultimate size limit. However, interpretation and analysis of the large, stochastic datasets produced by most quantum transport experiments remains an ongoing challenge to discovering much-needed structure-property relationships. Here, we introduce Segment Clustering, a novel unsupervised hypothesis generation tool for investigating single molecule break junction distance-conductance traces. In contrast to previous machine learning approaches for single molecule data, Segment Clustering identifies groupings of similar pieces of traces instead of entire traces. This offers a new and advantageous perspective into dataset structure because it facilitates the identification of meaningful local trace behaviors that may otherwise be obscured by random fluctuations over longer distance scales. We illustrate the power and broad applicability of this approach with two case studies that address common challenges encountered in single molecule studies: First, Segment Clustering is used to extract primary molecular features from a varying background to increase the precision and robustness of conductance measurements, enabling small changes in conductance in response to molecular design to be identified with confidence. Second, Segment Clustering is applied to a known data mixture to qualitatively separate distinct molecular features in a rigorous and unbiased manner. These examples demonstrate two powerful ways in which Segment Clustering can aid in the development of structure-property relationships in molecular quantum transport, an outstanding challenge in the field of molecular electronics.

The relative role of spatial and environmental processes on seasonal variations of phytoplankton beta diversity along different anthropogenic disturbances of subtropical rivers in China

The phytoplankton community structure is potentially influenced by both environmental and spatial processes. In addition, the relative importance of these two processes to phytoplankton assemblage will be affected by hydrological connectivity. However, the impacts of anthropogenic activities on phytoplankton beta diversity and the relative importance of these two processes to phytoplankton are still poorly understood, especially in water conservation areas. Here, we examined the relative importance of local and regional environmental control and spatial structuring of phytoplankton communities in five rivers with different degrees of disturbance during wet and dry seasons. We found that community structure and local environmental conditions varied greatly in seasons and rivers. The reference river (with minimum disturbance) had the highest homogeneity of environmental conditions and phytoplankton assemblage, while the excessive disturbance rivers (sand mining activities) had the greatest environmental heterogeneity and species dissimilarity between sites. Variation partitioning analysis showed that the phytoplankton community variation was mainly explained by the spatial variables in the wet season (summer and autumn) and winter, while the local environmental variables explained the largest variation of phytoplankton community in the dry season (spring). However, broad-scale variables were selected by redundancy analysis in both dry and wet seasons, which indicates that long-distance scales always have low river connectivity, regardless of whether the river is overflowing or drying up. Local environmental processes explained the most variation in phytoplankton community within all of the rivers, suggesting that deterministic processes usually work on relatively small spatial scales. However, this effect would be weakened by anthropogenic activities, especially sand mining activities. We inferred that sand mining activities increased the environmental heterogeneity and species dissimilarity between sites by causing watercourse habitat patches and obstructing river connectivity. On the other hand, as the excessive disturbance, sand mining activities significantly reduced the species richness and abundance of phytoplankton.

Electron microscopy combined with spatial analysis: quantitative mapping of the nano-assemblies of plasma membrane-associating proteins and lipids

The plasma membrane (PM) is a complex environment consisting of > 700 species of lipids and many different types of membrane-associating proteins. These lipids and membrane proteins are distributed heterogeneously into nanometer-sized domains, called nanoclusters. The lateral spatial segregation in the PM gives rise to different curvature and lipid composition, which determines the efficiency of effector binding and signal transmission. Here, we describe an electron microscopy (EM)-spatial mapping technique to quantify the extent of nanoclusters formation in the PM. The nano-assemblies in the PM are quantified via expressing the GFP-tagged proteins or lipid-binding domains in the cells, which are then immunolabeled with the gold nanoparticles pre-coupled to the anti-GFP antibody. The gold nanoparticles are visualized via the transmission EM at high magnification. The statistical analysis of the Ripley’s K-function calculates the spatial distribution of the gold nanoparticles. Important spatial parameters, such as the extent of nanoclustering, the clustered fraction, the number of proteins per cluster, the optimal size of a nanocluster, and the number of proteins localized to the PM, can be calculated. Further detailed aggregation pattern, such as the populations of monomers, dimers, trimers, and higher ordered oligomers, can also be extracted from the spatial analysis. The EM-bivariate analysis quantifies the extent of co-localization between two different components in the PM and provides key information on the protein–protein and the protein–lipid interactions over a long-distance scale from 8 to 240 nm.

Invasive Russian Knapweed (Acroptilon repens) Creates Large Patches Almost Entirely by Rhizomic Growth

Russian knapweed is an outcrossing perennial invasive weed in North America that can spread by both seed and horizontal rhizomic growth leading to new shoots. The predominant mode of spread at the local scale and dispersal at the long-distance scale informs control but has not been quantitatively researched. We used amplified fragment-length polymorphisms (AFLPs) of DNA collected from 174 shoots in two discrete patches of Russian knapweed at each of three locations in Montana. Out of the 174 shoots collected, we found nine AFLP genotypes. Three out of the six patches were monotypic; the other three patches each had one rare genotype. No genotypes were shared between patches. The maximum diameter of a genet (a genetic individual) was 56.5 m. These results indicate that patch expansion at the local scale is almost entirely by rhizomes that spread and develop new shoots. At the long-distance scale, dispersal is by seed. Controlling seed development through biological control and herbicide use may be effective at stopping long-distance dispersal but may not affect expansion of existing patches.

Microbial eukaryote plankton communities of high-mountain lakes from three continents exhibit strong biogeographic patterns.

Microbial eukaryotes hold a key role in aquatic ecosystem functioning. Yet, their diversity in freshwater lakes, particularly in high-mountain lakes, is relatively unknown compared with the marine environment. Low nutrient availability, low water temperature and high ultraviolet radiation make most high-mountain lakes extremely challenging habitats for life and require specific molecular and physiological adaptations. We therefore expected that these ecosystems support a plankton diversity that differs notably from other freshwater lakes. In addition, we hypothesized that the communities under study exhibit geographic structuring. Our rationale was that geographic dispersal of small-sized eukaryotes in high-mountain lakes over continental distances seems difficult. We analysed hypervariable V4 fragments of the SSU rRNA gene to compare the genetic microbial eukaryote diversity in high-mountain lakes located in the European Alps, the Chilean Altiplano and the Ethiopian Bale Mountains. Microbial eukaryotes were not globally distributed corroborating patterns found for bacteria, multicellular animals and plants. Instead, the plankton community composition emerged as a highly specific fingerprint of a geographic region even on higher taxonomic levels. The intraregional heterogeneity of the investigated lakes was mirrored in shifts in microbial eukaryote community structure, which, however, was much less pronounced compared with interregional beta-diversity. Statistical analyses revealed that on a regional scale, environmental factors are strong predictors for plankton community structures in high-mountain lakes. While on long-distance scales (>10000km), isolation by distance is the most plausible scenario, on intermediate scales (up to 6000km), both contemporary environmental factors and historical contingencies interact to shift plankton community structures.

Epidemiological analysis of bovine ephemeral fever in 2012-2013 in the subtropical islands of Japan.

BackgroundBovine ephemeral fever (BEF) is a febrile disease of cattle that is transmitted by arthropod vectors such as mosquitoes and Culicoides biting midges. An outbreak of BEF recently occurred in Ishigaki Island and surrounding islands that are located southwest of Japan. In this study, an epidemiological analysis was conducted to understand the temporal and spatial characteristics of the outbreak. Factors associated with the disease spread within Ishigaki Island were investigated by hierarchical Bayesian models. The possibility of between-island transmission by windborne vectors and transmission by long-distance migration of infected vectors were examined using atmospheric dispersion models.ResultsIn September 2012, the first case of the disease was detected in the western part of Ishigaki Island. In 1 month, it had rapidly spread to the southern part of the island and to surrounding islands, and led to 225 suspected cases of BEF during the outbreak. The dispersion model demonstrated the high possibility of between-island transmission by wind. Spatial analysis showed that paddy fields, farmlands, and slope gradients had a significant impact on the 1-km cell-level incidence risk. These factors may have influenced the habitats and movements of the vectors with regard to the spread of BEF. A plausible incursion event of infected vectors from Southeast Asia to Ishigaki Island was estimated to have occurred at the end of August.ConclusionThis study revealed that the condition of a terrain and land use significantly influenced disease transmission. These factors are important in assessing favorable environments for related vectors. The results of the dispersion model indicated the likely transmission of the infected vectors by wind on the local scale and on the long-distance scale. These findings would be helpful for developing a surveillance program and developing preventive measures against BEF.

SPECTROSCOPIC SURVEY OF G AND K DWARFS IN THE HIPPARCOS CATALOG. I. COMPARISON BETWEEN THE HIPPARCOS AND PHOTOMETRIC PARALLAXES

ABSTRACT The tension between the Hipparcos parallax of the Pleiades and other independent distance estimates continues even after the new reduction of the Hipparcos astrometric data and the development of a new geometric distance measurement for the cluster. A short Pleiades distance from the Hipparcos parallax predicts a number of stars in the solar neighborhood that are sub-luminous at a given photospheric abundance. We test this hypothesis using the spectroscopic abundances for a subset of stars in the Hipparcos catalog, which occupy the same region as the Pleiades in the color–magnitude diagram. We derive stellar parameters for 170 nearby G- and K-type field dwarfs in the Hipparcos catalog based on high-resolution spectra obtained using KPNO 4 m echelle spectrograph. Our analysis shows that, when the Hipparcos parallaxes are adopted, most of our sample stars follow empirical color–magnitude relations. A small fraction of stars are too faint compared to main-sequence fitting relations by Δ M V ≳ 0.3 ?> mag, but the differences are marginal at a 2 &sgr; ?> level, partly due to relatively large parallax errors. On the other hand, we find that the photometric distances of stars showing signatures of youth as determined from lithium absorption line strengths and R HK ′ ?> chromospheric activity indices are consistent with the Hipparcos parallaxes. Our result is contradictory to a suggestion that the Pleiades distance from main-sequence fitting is significantly altered by stellar activity and/or the young age of its stars, and provides an additional supporting evidence for the long-distance scale of the Pleiades.

The loss of asymmetry and reduced interhemispheric connectivity in adolescents with autism: A study using diffusion spectrum imaging tractography

Evidence from neuroimaging and neurobiological studies suggests that abnormalities in cortical–cortical connectivity involving both local and long-distance scales may be related to autism. The present study analyzed the microstructural integrity of the long-range connectivity related to social cognition and language processing with diffusion tractography among adolescents with autism compared with neurotypical adolescents. Tract-specific analyses were used to study the long-range connectivity responsible for integrating social cognition and language processing. Specifically, three pairs of association fibers and three portions of callosal fiber tracts were analyzed. Generalized fractional anisotropy (GFA) values were measured along individual targeted fiber tracts to investigate alterations in microstructure integrity. The asymmetry patterns were also assessed in three pairs of association fibers. In neurotypical participants, we found a consistent leftward asymmetry in three pairs of association fibers. However, adolescents with autism did not demonstrate such asymmetry. Moreover, adolescents with autism had significantly lower mean GFA in three callosal fiber tracts than neurotypical participants. The loss of leftward asymmetry and reduction of interhemispheric connection in adolescents with autism suggest alterations of the long-range connectivity involved in social cognition and language processing. Our results warrant further investigation by combining developmental and neurocognitive data.

Contracted Representation of Yang's Spacetime Algebra and Buniy-Hsu-Zee's Discrete Spacetime

Motivated by the recent proposition by Buniy, Hsu, and Zee with respect to discrete spacetime and finite spatial degrees of freedom of our physical world with short- and long-distance scales, l P and L, we reconsider the Lorentz-covariant Yang's quantized spacetime algebra (YSTA), which is intrinsically equipped with two such kinds of scale parameters, λ and R. In accordance with their proposition, we find the so-called contracted representation of YSTA with finite spatial degrees of freedom associated with the ratio R/λ, which gives a possibility of the divergence-free noncommutative field theory on YSTA. The canonical commutation relations familiar in the ordinary quantum mechanics appear as the cooperative Inonu-Wigner's contraction limit of YSTA, λ → 0 and R → ∓.

Renormalization Group in Bayesian Statistical Inference

The prediction in Bayesian framework is extended from the point of view of renormalization group. For this purpose, we first make it clear that the advantages of Bayesian statistical inference can be understood by an adaptive property of a long-distance length scale. This suggests a close connection of Bayesian statistical inference to renormalization group. Next, we show that a cumulative entropic error can be rewritten as an effective action, which directly leads to a renormalization group equation in non-parametric Bayesian statistical inference. As a result, we introduce a scaling part to a prior distribution, and determine it so that we can obtain better prediction performance. We discuss how prediction performance improves, taking an example of a density estimation problem.

Abelian Projection of Massive SU(2) Yang–Mills Theory

We derive an effective Abelian gauge theory (EAGT) of a modified SU(2) Yang–Mills theory. The modification is made by explicitly introducing mass terms of the off-diagonal gluon fields into pure SU(2) Yang–Mills theory, in order that Abelian dominance at a long-distance scale is realized in the modified theory. In deriving the EAGT, the off-diagonal gluon fields involving longitudinal modes are treated as fields that produce quantum effects on the diagonal gluon field and other fields relevant at a long-distance scale. Unlike earlier papers, a necessary gauge fixing is carried out without spoiling the global SU(2) gauge symmetry. We show that the EAGT allows a composite of the Yukawa and the linear potentials which also occurs in an extended dual Abelian Higgs model. This composite potential is understood to be a static potential between color-electric charges. In addition, we point out that the EAGT involves the Skyrme–Faddeev model.

On the existence of differences in luminosity between horizontal branch stars in globular clusters and in the field

The discrepancy between a LONG distance scale derived from Hipparcos based distances to globular clusters via main sequence fitting to local subdwarfs, and a SHORT distance scale derived from the absolute magnitude of field RR Lyraes via statistical parallaxes and the Baade-Wesselink method could be accounted for whether an intrinsic difference of about 0.1-0.2 mag was found to exist between horizontal branch (HB) stars populating the sparse general field and the dense globular clusters. In this paper we discuss the possible existence of such a systematic difference comparing the period-shifts observed for field and cluster RR Lyraes. Various approaches based on different parameters and data-sets for both cluster and field variables were used in order to establish the size of such a hypothetical difference, if any. We find that on the whole very small not significant differences exist between the period-metallicity distributions of field and cluster RR Lyraes, thus confirming with a more quantitative approach, the qualitative conclusions by Catelan (1998). This observational evidence translates into a very small difference between the horizontal branch luminosity of field and cluster stars, unless RR Lyraes in Globular Clusters are about 0.06 Mo more massive than field RR Lyrae at same metallicity, which is to be proven.

Opening up extra dimensions at ultralarge scales.

The standard picture of viable higher-dimensional theories is that direct manifestations of extra dimensions occur at short distances only, whereas long-distance physics is effectively four-dimensional. We show that this is not necessarily true in models with infinite extra dimensions. As an example, we consider a five-dimensional scenario with three 3-branes in which gravity is five dimensional at both short- and very long-distance scales, with conventional four-dimensional gravity operating at intermediate length scales. A phenomenologically acceptable range of validity of four-dimensional gravity extending from microscopic to cosmological scales is obtained without strong fine-tuning of parameters.

Structure−Property Correlations in Lithium Phosphate Glasses: New Insights from 31P ↔ 7Li Double-Resonance NMR

The macroscopic properties of binary alkali phosphate glasses are characterized by the presence of unexpected minima in the glass transition temperatures at alkali concentrations near 20−25 mol %. In the present study, the structural origin of this behavior is explored on the basis of multinuclear single- and double-resonance NMR experiments. 31P magic-angle spinning NMR spectra track the successive network depolymerization caused by Li2O addition, while 6Li chemical shifts indicate a lithium coordination number of four to five. The monotonic evolution of these spectra with increasing alkali content reveals that the nonlinear macroscopic behavior does not reflect any abrupt structural changes at the local level. In contrast, 31P{7Li} rotational echo double-resonance spectroscopy indicates substantial restructuring on longer distance scales, relating to the spatial arrangement of the lithium ions with respect to the phosphorus sites in the network. The data suggest that the average number of lithium atoms ...

The ΔS = 1 weak chiral lagrangian as the effective theory of the chiral quark model

We use the chiral quark model to construct the complete O( p 2) weak ΔS = 1 chiral lagrangian via the bosonization of the ten relevant operators of the effective quark lagrangian. The chiral coefficients are given in terms of f π the quark and gluon condesates and the scale-dependent NLO Wilson coefficients of the corresponding operators; in addition, they depend on the constituent quark mass M, a parameter characteristic of the model. All contributions of order N c 2 as well as N c and α s N c are included. The γ 5-scheme dependence of the chiral coefficients, computed via dimensional regularization, and the Fierz transformation properties of the operator basis are discussed in detail. We apply our results to the evaluation of the hadronic matrix elements for the decays K → 2 π, consistently including the renormalization induced by the meson loops. The effect of this renormalization is sizable and introduces a long-distance scale dependence that matches in the physical amplitudes the short-distance scale dependence of the Wilson coefficients.

Are cyons really anyons?

An unresolved issue in (2 + 1)-dimensional quantum mechanics is whether a composite object formed from a charged particle bound to a magentic flux tube carries fractional angular momentum. We argue that this is indeed so, that the result confirms Wilczek's generalized connection of spin and statistics, and that further confirmation is provided by the recently discovered induced charged and spin of flux tubes in (2 + 1)-dimensional QED, a theory in which different spin and statistics are defined at short- and at long-distance scales.

Scale-dependent analysis of phase structures in quantum field theories

The structure of the vacuum is studied in quantum field theories as a function of scale length R. As explicit examples, we analyze (1+1)-dimensional models which are exactly solvable in the leading 1/N approximation. In the Gross-Neveu model we find that chiral-symmetry breakdown occurs dynamically only at a long-distance scale (RR/sub c/); conversely, at a short-distance scale (R>R/sub c/) the gauge field is massive as a consequence of the symmetry breaking and does not produce a linear potential; R/sub c/ can be interpreted as the size of the bag within which quarks are confined. We also consider a modified Gross-Neveu model which has a permutation group S/sub L/ as an additional symmetry, where we analyze the dynamical breakdown of the S/sub L/ symmetry and the mass spectrum as a function of scale length R. In all these models the vacuum undergoes a phase transition in scale length R; for RR/sub c/ it is an ordered phase. It is emphasized that the critical point R/sub c/ is renormalization-group invariant.

Abelian dominance and quark confinement in Yang-Mills theories. II. Oblique confinement andη′mass

Making a working hypothesis of Abelian dominance at a long-distance scale, we analyze the U(1) problem as well as the confinement problem in the $\mathrm{SU}(N)$ Yang-Mills theory with the vacuum angle $\ensuremath{\theta}$. We show that quarks are confined only when $\frac{\ensuremath{\theta}}{2\ensuremath{\pi}}$ is a rational number such that $\frac{\ensuremath{\theta}}{2\ensuremath{\pi}}\ensuremath{\ne}\frac{(1+nN)}{\mathrm{mN}}$, $n$ and $m$ being integers. We also calculate a correlation function of the topological charge density $Q(x)={(16{\ensuremath{\pi}}^{2})}^{\ensuremath{-}1}\mathrm{Tr}{F}_{\ensuremath{\mu}\ensuremath{\nu}}{F}_{\ensuremath{\mu}\ensuremath{\nu}}^{*}(x)$ at $\ensuremath{\theta}=0$. We derive that $\ensuremath{\int}{d}^{4}x〈T{Q(x)Q(0)}〉=\frac{{N}^{2}}{128{\ensuremath{\pi}}^{4}(N\ensuremath{-}1){({\ensuremath{\alpha}}^{\ensuremath{'}})}^{2}}$, where ${\ensuremath{\alpha}}^{\ensuremath{'}}$ denotes the Regge slope of mesons. This formula yields \ensuremath{\sim}${(150\phantom{\rule{0ex}{0ex}}\mathrm{M}\mathrm{e}\mathrm{V})}^{4}$ in case of SU(3), which gives rise to a mass \ensuremath{\sim} 550 MeV to the ${\ensuremath{\eta}}^{\ensuremath{'}}$ meson through a chiral anomaly in QCD with massless quarks. This numerical result would explain the ${\ensuremath{\eta}}^{\ensuremath{'}}$ mass reasonably well in the approximation where pions are massless Goldstone bosons.

Abelian dominance and quark confinement in Yang-Mills theories

We define the Abelian component of the gauge field as a gauge-invariant object in the Yang-Mills theory. Then, by assuming that the Abelian component dominates in the theory at a long-distance scale, we demonstrate that quarks as well as gluons are confined by electric vortices. The vacuum structure is shown to depend on resolution $R$. That is, the vacuum has two phases in $R$ and monopole condensation occurs for $R\ensuremath{\ge}{R}_{c}$. The string tension of mesons is obtained as ${\ensuremath{\sigma}}_{q}=\frac{{{g}_{c}}^{2}}{3\ensuremath{\pi}{{R}_{c}}^{2}}$, where ${g}_{c}$ is the effective coupling constant at the critical resolution ${R}_{c}$. We estimate ${{R}_{c}}^{\ensuremath{-}1}$ to be 0.6 GeV in the presence of static quarks, and the bag constant ${B}^{\frac{1}{4}}$ to be 0.2-0.4 GeV. We also derive a relation ${\ensuremath{\alpha}}_{g}^{\ensuremath{'}}=\frac{1}{3}{\ensuremath{\alpha}}^{\ensuremath{'}}$ between Regge slopes of mesons (${\ensuremath{\alpha}}^{\ensuremath{'}}$) and of gluonia (${\ensuremath{\alpha}}_{g}^{\ensuremath{'}}$). This relation agrees with experimental data remarkably well provided that gluonia are identified with states lying on the Pomeranchuk trajectory.