Asymmetry Term Research Articles

No relationship found between dental fluctuating asymmetry, birthweight, and birth term in two modern North American samples.

Deciduous dental crowns primarily develop during gestation and early infancy and embody early life stress exposures. Composite measures of dental fluctuating asymmetry (DFA) generated from the deciduous teeth may therefore indicate cumulative gestational stress in developmental origins of health and disease (DOHaD) studies. This study examines whether higher composite measures of deciduous DFA are associated with low birthweight and prematurity, two aspects of birth phenotype consistently associated with increased morbidity and mortality risks in adulthood. We evaluated associations between composite deciduous DFA, birthweight, and birth term in two contemporary North American samples: an autopsy sample from New Mexico (n = 94), and sample from a growth cohort study in Burlington, Ontario (n = 304). Dental metric data for each sample was collected from postmortem CT scans and dental casts, respectively. Composite DFA was estimated using buccolingual (BL) and mesiodistal (MD) crown diameters from paired deciduous teeth. Contrary to expectations, the results of linear regression indicated no significant relationship between birthweight and DFA, or birth term and DFA, in either sample. Deciduous DFA does not predict aspects of birth phenotype associated with gestational stress. Birthweight and birth term are plastic relative to the more developmentally stable deciduous dentition, which may only subtly embody early life stress. We suggest that deciduous DFA should be utilized with caution in DOHaD studies until its relationship with gestational stress is clarified.

DeepEZ: A Graph Convolutional Network for Automated Epileptogenic Zone Localization From Resting-State fMRI Connectivity.

Epileptogenic zone (EZ) localization is a crucial step during diagnostic work up and therapeutic planning in medication refractory epilepsy. In this paper, we present the first deep learning approach to localize the EZ based on resting-state fMRI (rs-fMRI) data. Our network, called DeepEZ, uses a cascade of graph convolutions that emphasize signal propagation along expected anatomical pathways. We also integrate domain-specific information, such as an asymmetry term on the predicted EZ and a learned subject-specific bias to mitigate environmental confounds. We validate DeepEZ on rs-fMRI collected from 14 patients with focal epilepsy at the University of Wisconsin Madison. Using cross validation, we demonstrate that DeepEZ achieves consistently high EZ localization performance (Accuracy: 0.88 ± 0.03; AUC: 0.73 ± 0.03) that far outstripped any of the baseline methods. This performance is notable given the variability in EZ locations and scanner type across the cohort. Our results highlight the promise of using DeepEZ as an accurate and noninvasive therapeutic planning tool for medication refractory epilepsy. While prior work in EZ localization focused on identifying localized aberrant signatures, there is growing evidence that epileptic seizures affect inter-regional connectivity in the brain. DeepEZ allows clinicians to harness this information from noninvasive imaging that can easily be integrated into the existing clinical workflow.

Evolution of the isoscalar giant monopole resonance in the Ca isotope chain

Background: Two recent studies of the evolution of the isoscalar giant monopole resonance (ISGMR) within the calcium isotope chain report conflicting results. One study suggests that the monopole resonance energy, and thus the incompressibility of the nucleus, KA, increase with mass, which implies that Kτ, the asymmetry term in the nuclear incompressibility, has a positive value. The other study reports a weak decreasing trend of the energy moments, resulting in a generally accepted negative value for Kτ. Differences in the observed trends have been attributed to the use of different techniques to account for instrumental background and the physical continuum. Purpose: An independent measurement of the ISGMR in the Ca isotope chain is provided to gain a better understanding of the origin of possible systematic trends. Methods: Inelastically scattering of 196 MeV α particles were observed at small scattering angles, including 0∘, for a range of calcium targets (40,42,44,48Ca). The scattered α particles were momentum analyzed in the K600 magnetic spectrometer at iThemba LABS, South Africa. Monopole strengths spanning an excitation-energy range between 9.5 and 25.5 MeV were obtained using the difference-of-spectra (DoS) technique, adjusted to allow corrections for the variation of the angular shape of the sum of the L>0 multipoles as a function of excitation energy, and compared with previous results that employed the multipole-decomposition analysis (MDA) techniques. Results: The structure of the E0 strength distributions of Ca40,42,44 agrees well with the results from the previous measurement that support a weak decreasing trend of the energy moments, while no two datasets agree in the case of Ca48. Despite the variation in the structural character of E0 strength distribution from different studies, we find for all datasets that the moment ratios, calculated from the ISGMR strength in the excitation-energy range that covers the resonance peak, display at best only a weak systematic sensitivity to a mass increase. Conclusion: Different trends observed in the nuclear incompressibility are caused by contributions to the E0 strength outside of the region covering the resonance peak, and in particular for high excitation energies. While procedures exist to identify and subtract instrumental background, more work is required to characterize and subtract continuum background contributions at high excitation energies.4 MoreReceived 30 January 2022Accepted 16 May 2022DOI:https://doi.org/10.1103/PhysRevC.105.054319©2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasCollective levelsH & He induced nuclear reactionsNucleon-nucleon interactionsResonance reactionsProperties39 ≤ A ≤ 58Nuclear Physics

Multiple soft radiation at one-loop order and the emission of a soft quark\u2013antiquark pair

We consider the radiation of two or more soft partons in QCD hard-scattering at one-loop order. The corresponding scattering amplitude is singular, and the singular behaviour is controlled by a process-independent soft current. Using regularization in d=4 - 2epsilon space-time dimensions, we explicitly evaluate the ultraviolet and infrared divergent (epsilon -pole) terms of the one-loop soft current for emission of an arbitrary number of soft partons in a generic hard-scattering process. Then we consider the specific case of soft quark–antiquark (q{{bar{q}}}) emission and we compute the one-loop current by including the finite terms. We find that the one-loop soft-q{{bar{q}}} current exhibits a new type of transverse-momentum singularity, which has a quantum (absorptive) origin and a purely non-abelian character. At the squared amplitude (cross section) level, this transverse-momentum singularity produces contributions to multijet production processes in hadron collisions. The one-loop squared current also leads to charge asymmetry terms, which are a distinctive features of soft-q{{bar{q}}} radiation. We also extend these results to the cases of QED and mixed QCDtimes QED radiative corrections for soft fermion–antifermion emission.

Skew-kappa Distribution Functions and Whistler Heat Flux Instability in the Solar Wind: The Core-strahlo Model

Abstract Electron velocity distributions in the solar wind are known to have field-aligned skewness, which has been characterized by the presence of secondary populations such as the halo and strahl. Skewness may provide energy for the excitation of electromagnetic instabilities, such as the whistler heat flux instability (WHFI), which may play an important role in regulating the electron heat flux in the solar wind. Here we use kinetic theory to analyze the stability of the WHFI in a solar-wind-like plasma where solar wind core, halo, and strahl electrons are described as a superposition of two distributions: a Maxwellian core, and another population modeled by a Kappa distribution to which an asymmetry term has been added, representing the halo and also the strahl. Considering distributions with small skewness, we solve the dispersion relation for the parallel-propagating whistler mode and study its linear stability for different plasma parameters. Our results show that the WHFI can develop in this system and provide stability thresholds for this instability, as a function of the electron beta and the parallel electron heat flux, to be compared with observational data. However, since different plasma states, with different stability level to the WHFI, can have the same moment heat flux value, it is the skewness (i.e., the asymmetry of the distribution along the magnetic field), and not the heat flux, that is the best indicator of instabilities. Thus, systems with high heat flux can be stable enough to WHFI, so that it is not clear whether the instability can effectively regulate the heat flux values through wave–particle interactions.

Signature of magic numbers in light exotic nuclei

The advent of technology widened the study of shell closure for nuclei lying far away from the stability line. The classic shell closures are observed to be valid for nuclei near the stability line. The light exotic nuclei exhibit unique behavior compared to those of stable ones. The objective of this work is to study the shell closure in light nuclei near the neutron drip-line to the proton drip-line region. The systematics of two nucleon separation energy difference ([Formula: see text]) between calculated and experimental data are taken as a tool to study the shell closure of light nuclei. Nucleon separation energy is determined using the liquid drop model (LDM) expression with modified asymmetry and pairing energy terms. The light mass numbered isotopes and isotones as a function of even neutron and even proton numbers were considered for this work. The shell structure predicted by [Formula: see text] systematics is compared with the first excitation energy [Formula: see text]. The modified LDM is successful in identifying the shell structure properties of light nuclei in exotic region. The study supports the emergence of new shell closure and the disappearance of existing classic shell closure for both neutron and proton numbers. The shell structure predicted by [Formula: see text] systematics for isotopes (isotones) of magic nucleon number [Formula: see text] was in agreement with the results of [Formula: see text] analysis.

Abstract PS1-49: The effect of oncoplastic reduction on the incidence of post-operative breast lymphedema in breast cancer patients undergoing lumpectomy

Abstract Purpose / Objectives: In patients with macromastia, breast conservation surgery (BCS) followed by radiation therapy (RT) for the treatment of breast cancer may be associated with a different complication profile than those without macromastia. General complications of BCS followed by RT includes seroma, infection, wound complications, cosmetic deformity, asymmetry, acute versus long term arm and/or breast lymphedema. Oncoplastic reduction mammoplasty (ORM) aims to reduce breast volume while excising the tumor bed and its margins. Since breast volume was found to be a risk factor for chronic breast lymphedema, this study was performed to determine the impact of ORM on chronic breast lymphedema as well as other complications compared to BCS without ORM. Materials / Methods: We performed a retrospective chart review on patients who underwent lumpectomy with RT from 2014 to 2018. Chronic breast lymphedema (CBL) was defined as swelling that persisted >1 year post-RT. Breast volumes (BV) were determined by contoured breast volumes or, if unavailable, estimated by the 95% isodose volumes from the RT treatment planning system. Univariate analysis was used to evaluate various patient factors and treatment outcomes in women with BV ≥1300 cc compared to <1300 cc. These same factors were compared in women who underwent ORM vs. BCS alone. Multivariate regression analysis was used to evaluate factors associated with ≥1 complication. Logistic regression was performed to identify factors associated with the development of CBL. Results: The total population included 1173 patients, of which 51 (4.3%) underwent ORM and 1122 (95.7%) underwent BCS. 440 (37.5%) patients had BV ≥1300 cc and 733 (62.5%) patients had a BV <1300 cc. Multivariate regression analysis demonstrated that patients with BV ≥1300 cc had a higher BMI (OR=1.200, P<0.001), decreased risk of grade 2 radiation dermatitis (OR=0.457, P=0.002), and increased risk of CBL (OR=2.127, P=0.024) compared to patients with BV <1300 cc. However, oncoplastic reduction was associated with an increased risk of hematoma (OR=5.934, P<0.001), increased risk of wound dehiscence (OR=12.433, P<0.001), and decreased risk of seroma (OR=0.201, P<0.001) compared to BCS patients. Conclusions: Our data demonstrates that patients with breast volume > 1300 cc are at increased risk for developing several complications regardless of the presence of ORM. Those who had ORM experienced an increase in wound complications but having undergone ORM appeared to eliminate the increased risk of CBL associated with macromastia. This suggests that ORM should be considered at the time of BCS to reduce their future risk of CBL as there is no cure for this disease. Citation Format: Jenna Nicole Luker, Cara Canella, Sanjay Rama, Kelley Park, Renee Barry, Saheli Ghosh, Simeng Zhu, Yalei Chen, Jessica Bensenhaver, Eleanor Walker, Kenneth Levin, Maristella Evangelista, Dunya Atisha. The effect of oncoplastic reduction on the incidence of post-operative breast lymphedema in breast cancer patients undergoing lumpectomy [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS1-49.

Determination of the asymmetry term strength in the n–A elastic scattering process using a nonlocal optical model

In previous works, the imaginary surface and (or) the imaginary volume depths of the optical potential were parametrized as linear functions of the projectile’s incident energy and neutron-proton asymmetry (N – Z)/A of the target nucleus. However, the obtained asymmetry strength parameters were not robust nor unique. In this work, we determine values for the strength parameters by simultaneously fitting 38 angular distribution data sets corresponding to neutron elastic scattering off chains of isotopes. For each isotopic chain, we considered the data sets that are measured at the same energy. This minimises the effect of the known energy dependence of the optical model and projects the dependence on the asymmetry term, which in turn leads to more reliable values of the strength parameters. To demonstrate the significance of the obtained strength values, we use the model to predict elastic angular distributions for neutron scattering off nuclei not considered in the χ2 analysis. Our theoretical angular distributions are in good agreement with the measured data and are also comparable to the predictions of local global models. In addition, our predicted total elastic and total reaction cross sections are in fair overall agreement with experiment. An additional result of this work is the determination of a global set of nonlocal parameters that describe neutron elastic scattering off nuclei that fall in the mass range 24 ≤ A ≤ 208 corresponding to incident neutron energies between ≈10–30 MeV.

A nonlocal optical potential with a Gaussian nonlocality for proton elastic scattering off light 1p-shell nuclei

In a recent work we used the nonlocal optical model of Perey and Buck (Nucl Phys A 32:353, 1962) to fit the angular distribution data corresponding to neutron elastic scattering off light nuclei from $$^6\hbox {Li}$$ to $$^{18}\hbox {O}$$ over the 9–35 MeV energy range. Although such nuclei posses diffuse edges that complicate the scattering process, the model resulted in improved angular distribution fits compared to those obtained using local optical models. In this work we extend the treatment to the case of proton elastic scattering off light 1p-shell nuclei, but consider the wider 10–70 MeV energy range. No single global set of nonlocal parameters adequately described the measured data across the entire energy range. Instead, we obtained two global sets of fixed nonlocal parameters; one corresponds to the 10–39 MeV range, the other is for the higher 40–70 MeV incident energies. Each set resulted in angular distribution fits which are in very good agreement with experimental data even in the large-angle scattering region, which is usually endowed by nonlocal effects. The fits were improved even further by expressing the imaginary volume and imaginary surface depths as linear functions of energy and the $$(N-Z)/A$$ asymmetry term. This indicates that there is still need for energy-dependent parameters even when nonlocality is explicitly included in the potential. We also used the model to predict elastic angular distributions for proton scattering off nuclei not included in the fitting procedure. The theoretical predictions showed very good agreement with experiment. As a further test of the nonlocal model, we calculated total reaction cross sections for proton scattering off light 1p-shell nuclei. Our predictions are in fair overall agreements with the experimental data.

Compression-mode resonances in the calcium isotopes and implications for the asymmetry term in nuclear incompressibility

Recent data on isoscalar giant monopole resonance (ISGMR) in the calcium isotopes 40,44,48Ca have suggested that Kτ, the asymmetry term in the nuclear incompressibility, has a positive value. A value of Kτ>0 is entirely incompatible with present theoretical frameworks and, if correct, would have far-reaching implications on our understanding of myriad nuclear and astrophysical phenomena. This paper presents results of an independent ISGMR measurement with the 40,42,44,48Ca(α,α′) reaction at Eα=386 MeV. These results conclusively discount the possibility of a positive value for Kτ, and are consistent with the previously-obtained values for this quantity.

Interaction-induced edge states in HgTe/CdTe quantum wells under a magnetic field

In this paper, we study doped HgTe/CdTe quantum well with Hubbard-type interaction under perpendicular magnetic field using a lattice Bernevig-Hughes-Zhang (BHZ) model with a bulk inversion asymmetry (BIA) term. We show that the BIA term is strongly enhanced by interaction around the region when the band inversion of the topological insulator is destroyed by a magnetic field. The enhanced BIA term creates edge-like electronic states which can explain the experimentally discovered edge conductance in doped HgTe/CdTe quantum well at similar magnetic field regime.

A nonlocal optical model for neutron scattering from light 1p-shell nuclei

Nonlocal effects result in complications when predicting scattering observables. This is usually seen when one analyses the data for nucleon scattering off light 1p-shell nuclei using local optical model potentials. In this work we employ the nonlocal optical model of Perey and Buck (1962) [10] to study the neutron-light nucleus scattering process. By fitting the individual elastic angular distributions we determine energy-dependent, target-specific potential parameters. Then, for each nucleus, a constant set of nonlocal parameters is obtained by simultaneously fitting the corresponding elastic angular distributions. The good quality of the fits prompted us to search for a global constant set of nonlocal parameters by simultaneously fitting a large number elastic angular distribution sets for neutron scattering off light nuclei from 6Li to 18O over the energy range 9 to 35 MeV. We also show that the implicit inclusion of nonlocality in the optical model does not fully remove the need for energy-dependent potential parameters. This is achieved by expressing the nonlocal imaginary volume and surface depths of the constant global set as linear functions of energy and the asymmetry term. The effectiveness of this set is tested by applying it to additional light nuclei and energies outside the fitted range. The predicted elastic angular distributions compared well with the measured data.

Influence of nuclear isospin and angular momentum on α-decay half-lives

In this work the influence of isospin and angular momentum on two versions of Ren formula has been studied by adding the asymmetry and angular momentum terms for α-decay half-lives. We obtain coefficients for the two new formulae (New Ren A, New Ren B) and previous Ren (Ren B) formula, the coefficient are determined by least square fitting method of 356 nuclei for the even–even, even–odd, odd–even and odd–odd sets of nuclei. For each formula, the average and standard deviations have been evaluated. The new expressions provide good agreement between the calculated and experimental data for the α-decay half-lives when we consider the influence of nuclear isospin and angular momentum.

Application of a GARCH, TGARCH, and EGARCH, Models to Test the Spot GBP/USD Exchange Rate Volatility.

In this article, we have tested the volatility of the returns of the spot exchange rate of GBP/USD for changing conditional variances. Generalized autoregressive conditional heteroskedastic models, GARCH, threshold generalized autoregressive conditional heteroskedastic models, (TGARCH), and exponential generalized autoregressive conditional heteroskedastic models, (EGARCH) models take into account the non- linearity that arises in financial time series. We have checked the volatility clusters for a long period of time that arises in the financial times series of returns or the fact that large and small values occur persistently in clusters. By applying a GARCH (1,1) model, we have found that the variance equation of the natural logarithmic returns of the GBP/USD spot rate are very significant. The coefficients of the ARCH and GARCH effects are statistically significant, which is a sign that the conditional variance and volatility clusters are persistent. By applying a TGARCH (1,1) model, we have found that there is no leverage effect. By applying an EGARCH (1,1) model, we have found that the asymmetry term is not statistically significant at the 5% significance level. Negative shocks do not imply a higher next period conditional variance than positive shocks of the same sign. There is no serial correlation in the residuals of the GARCH (1,1), TGARCH (1,1), and EGARCH (1,1), models. The residuals of the GARCH (1,1), TGARCH (1,1), and EGARCH (1,1) are homoskedastic and there is no additional ARCH effect. Finally, there are negative and positive shocks that are driving the GBP/USD exchange spot rate away from normality. The data that we have used are monthly returns starting from 01/01/1990 to 01/01/2013, which total to 276 observations. The data was obtained from the Federal Reserve Statistical Release Department and the symbol of the series is H.10.

A note on the Nelson-Cao inequality constraints in the GJR-GARCH model: is there a leverage effect?

The majority of the stylised facts of financial time series and several value-at-risk measures are modelled via univariate or multivariate GARCH processes. It is not rare that advanced GARCH models fail to converge for computational reasons, and a usual parsimonious approach is the GJR-GARCH model. There is a disagreement in the literature and the specialised econometric software, on which constraints should be used for the parameters, introducing indirectly the distinction between asymmetry and leverage. We show that the approach used by various software packages is not consistent with the Nelson-Cao inequality constraints. Implementing Monte Carlo simulations, despite of the results being empirically correct, the estimated parameters are not theoretically coherent with the Nelson-Cao constraints for ensuring positivity of conditional variances. On the other hand ruling out the leverage hypothesis, the asymmetry term in the GJR model can take negative values when typical constraints are imposed.

Noise Created Through the Interactions of Arbitrageurs and Noise Traders in the FOREX Market. An Analysis Based on ARCH, GARCH, TGARCH and EGARCH Models

In this article, we have tested the volatility of the returns of the spot exchange rate of EURO/USD, the returns of a real exchange rate index and the money supply, (M1), for changing conditional variances. Autoregressive Conditional Heteroskedastic models (ARCH), Generalized Autoregressive Conditional Heteroskedastic models, (GARCH), Threshold GARCH, (TGARCH) and exponential, (EGARCH) models take into account the non-linearity that arises in financial time series. In this article, we are not testing the regressive relationship between exchange rate volatility and macroeconomic indicators such as the money supply, interest rates, and real GDP. We have checked the volatility clusters for a long period of time that arises in the financial times series of returns or the fact that large and small values occur persistently in clusters. In other words, we have concluded that negative shocks implied a higher next period conditional variance than positive shocks of the same extent. The asymmetry terms are highly statistically significant by using the family of autoregressive models. We have found that there is a significant positive and negative volatility clusters, which confirms the ARCH and GARCH, TGARCH and EGARCH effect on the time series of the EURO/USD spot rate, based on the F-statistic, the Lagrange Multiplier, (LM), the leverage effect, the Jarque – Bera normality tests. The data that we have used are monthly returns starting from 01/01/2000 to 01/01/2013, which total to 156 observations. The data was obtained from the Federal Reserve Statistical Release Department and the symbols of the series are H.10 and H.6.

A note on the Nelson-Cao inequality constraints in the GJR-GARCH model: is there a leverage effect?

The majority of stylized facts of financial time series and several Value-at-Risk measures are modeled via univariate or multivariate GARCH processes. It is not rare that advanced GARCH models fail to converge for computational reasons, and a usual parsimonious approach is the GJR-GARCH model. There is a disagreement in the literature and the specialized econometric software, on which constraints should be used for the parameters, introducing indirectly the distinction between asymmetry and leverage. We show that the approach used by various software packages is not consistent with the Nelson-Cao inequality constraints. Implementing Monte Carlo simulations, despite of the results being empirically correct, the estimated parameters are not theoretically coherent with the Nelson-Cao constraints for ensuring positivity of conditional variances. On the other hand ruling out the leverage hypothesis, the asymmetry term in the GJR model can take negative values when typical constraints like the condition for the existence of the second and fourth moments, are imposed.

Analysis of Herding in Reits of an Emerging Market: The Case of Turkey

Executive SummaryIn this paper, we examine herding behavior in Turkish REITs (TREITs) by using daily closing prices over the period from 07/1/2007 to 05/30/2016. To the best of our knowledge, we are the first to examine the herding behavior in TREITs by utilizing Chang, Cheng, and Khorana's (2000) methodology. Our results indicate herding behavior, the presence of directional asymmetry, and a linear relation between volatility and herding. The evidence also suggests that herding is a persistent phenomenon and increases during market stress. We also find transition periods in both with/without asymmetry term models. Our findings suggest critical implications for portfolio managers and supervisors dealing with the behavioral aspects of irrationality arising from herding behaviors in emerging stock markets and TREITs.

The quantitative Faber–Krahn inequality for the Robin Laplacian

We prove a quantitative form of the Faber–Krahn inequality for the first eigenvalue of the Laplace operator with Robin boundary conditions. The asymmetry term involves the square power of the Fraenkel asymmetry, multiplied by a constant depending on the Robin parameter, the dimension of the space and the measure of the set.

Estimation of the alpha decay of Platinum isotopes using different versions of theoretical formula

The alpha decay half-lives of even–even and even–odd Platinum (Pt) nuclei have been studied within the Coulomb and proximity potential model (CPPM). The present study is restricted to even–even nuclei with [Formula: see text]–198. The results are compared with other calculations such as the Semi-empirical formula (SemFIS) from Poenaru et al. based on fission theory of alpha decay, the Viola–Seaborg (VS), Royer (R) and Brown formulae. Also, the alpha decay half-lives have been calculated using the Scaling law of Brown (SLB), the Universal Decay Law (UDL) of Qi et al., the Scaling Law of Horoi et al. (SLH), and Akrawy–Dorin formula (ADF) of Akrawy and Poenaru, which are the Royer modified formula for alpha decay half-live by adding asymmetry term.