Dependence Of Asymmetry Research Articles

Causal discovery in heavy-tailed models

Causal questions are omnipresent in many scientific problems. While much progress has been made in the analysis of causal relationships between random variables, these methods are not well suited if the causal mechanisms only manifest themselves in extremes. This work aims to connect the two fields of causal inference and extreme value theory. We define the causal tail coefficient that captures asymmetries in the extremal dependence of two random variables. In the population case, the causal tail coefficient is shown to reveal the causal structure if the distribution follows a linear structural causal model. This holds even in the presence of latent common causes that have the same tail index as the observed variables. Based on a consistent estimator of the causal tail coefficient, we propose a computationally highly efficient algorithm that estimates the causal structure. We prove that our method consistently recovers the causal order and we compare it to other well-established and nonextremal approaches in causal discovery on synthetic and real data. The code is available as an open-access R package.

Polarization dependent beaming properties of a plasmonic lattice laser

We study beaming properties of laser light produced by a plasmonic lattice overlaid with organic fluorescent molecules. The crossover from spontaneous emission regime to stimulated emission regime is observed in response to increasing pump fluence. This transition is accompanied by a strong reduction of beam divergence and emission linewidth due to increased degree of spatial and temporal coherence, respectively. The feedback for the lasing signal is shown to be mainly one-dimensional due to the dipolar nature of the surface lattice resonance. Consequently, the beaming properties along x and y directions are drastically different. From the measurements, we obtain the M 2 value along both principal directions of the square lattice as a function of the pump fluence. Our work provides the first detailed analysis of the beam quality in plasmonic lattice lasers and reveals the underlying physical origin of the observed strong polarization dependent asymmetry of the lasing signal.

Polarization asymmetry of the dark-resonance frequency dependence on the magnetic field

We demonstrate the possibility of suppressing the linear response of the coherent population trapping resonance frequency to variations in the external magnetic field. The suppression can be achieved at a specific value of the clock magnetic field B due to the competition between the frequency pulling by neighboring resonances and the quadratic Zeeman shift. The effect is possible only with certain combinations of the optical field polarization and the direction of the magnetic field. An incorrect field configuration can significantly increase the magnetic-induced frequency shifts.

The Effect Mechanism of Tie Strength of Supply Networks on Risk Sharing: Based on the Empirical Data of China’s Automobile Manufacturing Industry

Based on the research perspective of the cooperation risk and opportunistic risk between supply network enterprises, this article investigates the mechanism of how tie strength between manufacturers and suppliers influences risk sharing among enterprises from two dimensions of tie strength: structural strength and relational strength. In particular, we introduce how asymmetry of dependence moderates the relationship between tie strength and risk sharing. We surveyed China’s domestic auto OEMs and their first-tier suppliers in China through 260 questionnaires and used a hierarchical regression model as a research method to carry out the empirical analysis and test. We found an inverted U-shaped relationship between tie strength and risk sharing among enterprises, and asymmetry of dependence has a significant negative adjustment function on relational strength of the tie and risk-sharing relationship, while there is no significant adjustment function on the structural strength of it. Our findings suggest that keeping moderate tie strength among enterprises is conducive to achieving risk sharing. Moreover, trust and reciprocity is inhibitory regarding the adjustment effect of asymmetry of the dependence influencing relational strength and risk-sharing relationship. However, the structural strength and risk-sharing relationship are not interfered with by the adjustment function of asymmetry of dependence; that is, structural strength plays a decisive role in risk sharing.

Charge-dependent transverse momentum and its impact on the search for the chiral magnetic wave

The chiral magnetic wave (CMW) is sought using the charge asymmetry (${A}_{\mathrm{ch}}$) dependence of anisotropic flow in heavy-ion collisions. The charge-dependent transverse momentum (${p}_{\mathrm{T}}$), however, could play a role as a background. With the string fragmentation models, including pythia, we demonstrate the origin of the ${A}_{\mathrm{ch}}\text{\ensuremath{-}}{p}_{\mathrm{T}}$ correlation and its connection with the local charge conservation (LCC). The impact of ${A}_{\mathrm{ch}}\text{\ensuremath{-}}{p}_{\mathrm{T}}$ and its behavior in varied kinematic windows are also discussed. This study provides more insights for the search for the CMW and comprehending the collective motion of the quark-gluon plasma.

Extracting the number of short-range correlated nucleon pairs from inclusive electron scattering data

The extraction of the relative abundances of short-range correlated (SRC) nucleon pairs from inclusive electron scattering is studied using the generalized contact formalism (GCF) with several nuclear interaction models. GCF calculations can reproduce the observed scaling of the cross-section ratios for nuclei relative to deuterium at high-$x_B$ and large-$Q^2$, $a_2=(\sigma_A/A)/(\sigma_d/2)$. In the non-relativistic instant-form formulation, the calculation is very sensitive to the model parameters and only reproduces the data using parameters that are inconsistent with ab-initio many-body calculations. Using a light-cone GCF formulation significantly decreases this sensitivity and improves the agreement with ab-initio calculations. The ratio of similar mass isotopes, such as $^{40}$Ca and $^{48}$Ca, should be sensitive to the nuclear asymmetry dependence of SRCs, but is found to also be sensitive to low-energy nuclear structure. Thus the empirical association of SRC pair abundances with the measured $a_2$ values is only accurate to about $20\%$. Improving this will require cross-section calculations that reproduce the data while properly accounting for both nuclear structure and relativistic effects.

Transverse momentum dependent forward neutron single spin asymmetries in transversely polarized p+p collisions at s=200 GeV

In 2015, the PHENIX collaboration has measured very forward ($\eta>6.8$) single-spin asymmetries of inclusive neutrons in transversely polarized proton-proton and proton-nucleus collisions at a center of mass energy of 200 GeV. A previous publication from this data set concentrated on the nuclear dependence of such asymmetries. In this measurement the explicit transverse-momentum dependence of inclusive neutron single spin asymmetries for proton-proton collisions is extracted using a bootstrapping-unfolding technique on the transverse momenta. This explicit transverse-momentum dependence will help improve the understanding of the mechanisms that create these asymmetries.

Supplier dependence asymmetry and investment in innovation: The role of psychological uncertainty

A key source of competitive advantage for large firms accrues from investments in innovative products and processes by their suppliers, incentivized by a positive relationship climate. A fundamental hindrance lies in a condition that commonly characterizes buyer-supplier relationships: asymmetric levels of dependence between business partners. Such asymmetry has been shown to be detrimental to the relationship, enhancing the likelihood of conflict, and negatively impacting the performance of the more dependent party. Considering that such dependence asymmetry is likely to persist, large buyers face the challenge of promoting a relationship environment that provides an incentive for suppliers to invest in innovation. In this study, we propose that large, dominant buyers can influence suppliers' intentions and behaviors by mitigating the effects of their perceived riskiness and ambiguity that emerge from a situation of dependence asymmetry. Specifically, using the lens of resource dependence theory, we investigate the effects of these two psychological dimensions of uncertainty on a supplier's trust, commitment, and willingness to invest in innovation, as well as the moderating effect of a buyer's information sharing in shaping a supplier's perceived uncertainty. The model is tested with a scenario-based experiment and results are corroborated by interviews with experienced managers of retail suppliers. Our findings indicate that a supplier's dependence on a large buyer increases its perception of ambiguity and riskiness in the relationship, negatively impacting its trust, commitment, and willingness to invest in innovation. However, a buyer who shares relevant and timely information with the supplier mitigates its perceived uncertainty, promoting the supplier's positive attitudes towards the buyer and incentivizing innovation. Sharing operational and strategic information such as point-of-sales data, sales forecasts, or strategic plans, becomes a valuable strategy to powerful buyers in the pursuit of becoming a preferred customer and enhancing a supplier's resource mobilization towards the relationship.

Statistical Characteristics of Field‐Aligned Currents in the Plasma Sheet Boundary Layer

AbstractEnergy and momentum can be transferred from the magnetosphere to the ionosphere through field‐aligned currents (FACs), which show seasonal variations due to seasonal variation of the ionospheric conductance. Using Magnetospheric Multiscale Mission observations, we investigate the characteristics of kinetic‐scale (close to local ion inertial length) FACs in the plasma sheet boundary layer (PSBL), such as occurrence rate, magnitude, and carriers. The results show that: (1) the occurrence rates of FACs exhibit a trident distribution; they are also larger in the northern hemisphere than in the southern hemisphere, especially for the earthward FACs. (2) Distribution patterns vs. plasma β are different for the beam‐type and the flow‐type FACs. Flow‐type FACs are observed closer to the central plasma sheet (higher β), and their occurrence rate decreases linearly toward the tail lobe (lower β), while the beam‐type FACs are mainly and equally distributed within 0.1 < β < 1.0. (3) The magnitude of FACs shows little dependence on β, and generally increases closer to the Earth. (4) Occurrence rate and magnitude of FACs both increase during active periods, consistent with ionospheric observations. (5) The main carriers for FACs in the PSBL are thermal electrons, while cold electrons also contribute occasionally, especially during active periods. Hemispheric asymmetry of occurrence rate and dependence on geomagnetic activity of the kinetic‐scale FACs in the PSBL are consistent with FACs at ionospheric altitudes. This fact demonstrates that kinetic‐scale FACs are significant in magnetosphere‐ionosphere coupling and illustrates the possible ionospheric feedback effects to the magnetosphere in the nightside.

Mapping cortical and subcortical asymmetries in substance dependence: Findings from the ENIGMA Addiction Working Group.

Brain asymmetry reflects left-right hemispheric differentiation, which is a quantitative brain phenotype that develops with age and can vary with psychiatric diagnoses. Previous studies have shown that substance dependence is associated with altered brain structure and function. However, it is unknown whether structural brain asymmetries are different in individuals with substance dependence compared with nondependent participants. Here, a mega-analysis was performed using a collection of 22 structural brain MRI datasets from the ENIGMA Addiction Working Group. Structural asymmetries of cortical and subcortical regions were compared between individuals who were dependent on alcohol, nicotine, cocaine, methamphetamine, or cannabis (n=1,796) and nondependent participants (n=996). Substance-general and substance-specific effects on structural asymmetry were examined using separate models. We found that substance dependence was significantly associated with differences in volume asymmetry of the nucleus accumbens (NAcc; less rightward; Cohen's d=0.15). This effect was driven by differences from controls in individuals with alcohol dependence (less rightward; Cohen's d=0.10) and nicotine dependence (less rightward; Cohen's d=0.11). These findings suggest that disrupted structural asymmetry in the NAcc may be a characteristic of substance dependence.

Nuclear temperature and its dependence on the source neutron-proton asymmetry deduced using the Albergo thermometer

Albergo thermometers with double isotope, isotone, and isobar yield ratio pairs with one proton and/or neutron difference are investigated. Without any extra sequential decay correction, a real temperature value of $4.9\ifmmode\pm\else\textpm\fi{}0.5$ MeV is deduced from the yields of the experimentally reconstructed primary hot intermediate mass fragments (IMFs) from $^{64}\mathrm{Zn}+^{112}\mathrm{Sn}$ collisions at 40 MeV/nucleon using the Albergo thermometer for the first time. An experimental sequential decay correction from the apparent temperatures to the real ones for 12 other reaction systems with different neutron-proton ($N/Z$) asymmetries in the same experiment, $^{70}\mathrm{Zn}$, $^{64}\mathrm{Ni}$ on $^{112,124}\mathrm{Sn}$, $^{58,64}\mathrm{Ni}$, $^{197}\mathrm{Au}$, and $^{232}\mathrm{Th}$ at 40 MeV/nucleon, is performed using an empirical correction factor approach of Tsang et al. [Phys. Rev. Lett. 78, 3836 (1997)] with the deduced 4.9-MeV temperature value. The dependence of nuclear temperature on the source $N/Z$ asymmetry is further investigated using these deduced real source temperature values from the present 13 systems. It is found that the deduced real source temperatures at the present source $N/Z$ range show a rather weak dependence on the source $N/Z$ asymmetry. By comparison between our previous results and those from other independent experiments, a consistent description for the $N/Z$ asymmetry dependence of nuclear temperature is addressed.

Respects of Dependence and Symmetry

In this article I discuss several apparent counterexamples to the asymmetry of ontological dependence. These counterexamples were introduced in discussions about grounding, but they can affect every theory of ontological dependence. I show that, if one adopts metaontological pluralism (i.e., the view according to which there are many dependence relations), one has some advantages when it comes to defending the asymmetry of dependence. In Section 1, I introduce metaontological pluralism and my own version of it, which is based on Respect-of-Dependence Relations (rd-relations). I then single out five strategies to deal with apparent cases of symmetric dependence and show that two of them are only available to metaontological pluralists. In Sections 2, 3, and 4 I deal with cases of symmetric dependence by adopting these strategies. Finally, in Section 5, I anticipate and reply to three objections against my account.

Asymmetric carrier transport and weak localization in few layer graphene grown directly on a dielectric substrate.

Temperature-dependent electrical and magneto-transport measurements have been performed on devices composed of few layer (4L) graphene grown directly on SiO2/Si substrates using the CVD method. An intrinsic energy band-gap of 4.6 meV in 4L graphene is observed, which primarily dictates the current transport at T <50 K. Unusual temperature dependent electron-hole conduction asymmetry is observed at T >50 K, which can be explained in the framework of the defect scattering of relativistic charge carriers. Magneto-transport measurements reveal a weak localization effect sustainable till T >200 K. The coexistence of phonon mediated carrier mobility and defect induced weak localization effects in measuring devices suggests low disorder and impurity scattering.

Fair Private Governance for the Platform Economy: EU Competition and Contract Law Applied to Standard Terms

In recent years a platform economy has emerged that is dominated by undertakings such as Google, Amazon, Facebook, Apple and Microsoft. They have established a form of private governance vis-a-vis their consumers and customers by means of standard terms that create a risk of exploitation. This trend clashes with the internal market effort of the EU that is predicated on consumer rights and fair competition to address market failures such as market power, information asymmetry and asymmetrical contractual dependency. In this article we examine how the resulting tensions can be addressed by means of EU competition and contract law. This is based on enforcing fairness by requiring (i) the implementation of proportionality – balancing interests – and (ii) respect of the duty of care, in the sense of compliance by design. Jointly this can be seen as an expression of accountability that needs to be made explicit. Apart from pre-existing case law and legislation we take into account the December 2020 Commission proposals for platform regulation, as well as behavioral insights into consumer behavior.

Importance of non-flow background on the chiral magnetic wave search

An observable sensitive to the chiral magnetic wave (CMW) is the charge asymmetry dependence of the π− and π+ anisotropic flow difference, Δνn(Ach). We show that, due to non-flow correlations, the flow measurements by the Q-cumulant method using all charged particles as reference introduce a trivial linear term to Δνn(Ach). The trivial slope contribution to the triangle flow difference Δν3(Ach) can be negative if the non-flow is dominated by back-to-back pairs. This can explain the observed negative Δν3(Ach) slope in the preliminary STAR data. We further find that the non-flow correlations give rise to additional backgrounds to the slope of Δν2(Ach) from the competition among different pion sources and from the larger multiplicity dilution to π+ (π−) at positive (negative) Ach.

Asymmetric tail dependence between stock market returns and implied volatility

The main objective of this paper is to analyze tail dependence between returns and changes in implied volatility. We verify the asymmetry in dependence of positive and negative extreme returns with implied volatility. This empirical study is based on 678 series of options listed on the Warsaw Stock Exchange, in Poland during the period 2007 to 2018. We use a copula methodology and a nonparametric asymptotic dependence approach to estimate tail dependence. We find that changes in implied volatility are asymptotically independent on positive extreme returns and significantly dependent on negative extreme returns. The same asymmetry we obtained for call and put options regardless of their moneyness. The empirical evidence also suggests that implied volatility of put options rise more than that for call options in crash times and falls deeper in times of low volatility.

Sample Size for Bioindication of Pollution Level by the Method of Fluctuating Asymmetry

Bioindication is a convenient tool for assessing the environmental situation and the level of pollution of natural and man-made landscapes. One of the most important indicator is the fluctuating asymmetry of plant organs, less common – organs of animals and humans. In 2019, we studied the fluctuating asymmetry of Pinus sylvestris L. located in the industrial zone (Yanino-1), as well as in city parks of St. Petersburg (Alexandrino, Sergievka) and Moscow (Sokolniki). The dependence of the fluctuation asymmetry on the sample size is studied, the volumes of samples are substantiated, an algorithm for processing experimental data is proposed, which allows increasing the accuracy of experiments, avoids false positive or false

Flexible modelling of multivariate risks in pricing margin protection insurance: modelling portfolio risks with mixtures of mixtures

ABSTRACT Margin Protection Programs (MPPs) are relatively new insurance plans, introduced by USDA’s Risk Management Agency (RMA). The attractiveness of these risk management instruments lies in the fact that the financial stability of agricultural production and farming operations is more dependent on margins than solely revenues, which neglect production costs, as is the case for Revenue Protection Programs (RPPs). This article examines the structure and rating of margin protection insurance policies by considering a broad class of high-dimensional copula models that parameterize the dependence among multivariate sources of risks. A variety of copula methods, including Archimedean Copulas (ACs), Mixture Copulas (MCs), and Vine Copulas (VCs) are used to analyse the dependence structure between revenues and input costs. In terms of methodology, flexible mixtures of parametric distributions are applied to characterize marginal densities, and likewise flexible mixtures of alternative copulas are used to model dependence. This article also argues that the rating methodology that accounts for irregular and anomalous features of dependence such as asymmetry, non-linearity, non-ellipticity, and tail dependence between input prices and output prices can result in more accurate premiums, and therefore, can increase the hedging effectiveness of the MPPs and the market efficiency in the US crop insurance market.

The Evolution of Mutualistic Dependence

While the importance of mutualisms across the tree of life is recognized, it is not understood why some organisms evolve high levels of dependence on mutualistic partnerships, while other species remain autonomous or retain or regain minimal dependence on partners. We identify four main pathways leading to the evolution of mutualistic dependence. Then, we evaluate current evidence for three predictions: ( a) Mutualisms with different levels of dependence have distinct stabilizing mechanisms against exploitation and cheating, ( b) less dependent mutualists will return to autonomy more often than those that are highly dependent, and ( c) obligate mutualisms should be less context dependent than facultative ones. Although we find evidence supporting all three predictions, we stress that mutualistic partners follow diverse paths toward—and away from—dependence. We also highlight the need to better examine asymmetry in partner dependence. Recognizing how variation in dependence influences the stability, breakdown, and context dependence of mutualisms generates new hypotheses regarding how and why the benefits of mutualistic partnerships differ over time and space.

The effects of density dependence and habitat preference on species coexistence and relative abundance.

In plant communities, some mechanisms maintain differences in species' abundances, while other mechanisms promote coexistence. Asymmetry in conspecific negative density dependence (CNDD) and/or habitat preference is hypothesized to shape relative species abundance, whereas community compensatory trends (CCTs) induced by community-level CNDD and heterospecific facilitation are hypothesized to promote coexistence. We use survey data from three 1-ha permanent dynamic plots in a subtropical forest over the course of a decade to find out which of these processes are important and at which life-history stages (the seedling, sapling, and juvenile stages) they exert their effects. CNDD was not related to abundance in any of the life-history stages. Suitable habitats positively influenced plant abundance at all tested life stages, but especially so for juveniles. Community-level CNDD of seedling neighbors was detected at the seedling stage, while heterospecific facilitation was detected across all tested life-history stages. A CCT in seedling survival was detected, but there was no evidence for such trends across the other life-history stages. Altogether, our results suggest that habitat specificity increases the rarity of species, whereas a CCT at the seedling stage, which is likely to be induced by CNDD and heterospecific facilitation, enables such species to maintain their populations.