Maximal Asymmetry Research Articles

Predictive importance of index of asymmetry in recovery following stroke

Quantitative electroencephalography (QEEG) has been proved as a powerfully tool for prediction of the stage of residual functional disable. For predictive value of QEEG, individual profile of every patient is most important. It has been demonstrated that Index of brain symmetry (BSI) present specific asymmetry of power spectra between two brain hemispheres and it has been normalized from 0 (perfect symmetry) and 1 (maximal asymmetry). We included in our analysis 86 normal subjects in EEG recording. We did frequency analysis using Fast Fourier transformation (FFT) in power spectra for 16 derivations and 20 frequency bands, from 0 to 20Hz, with step of 1. On the base of that data, we got normal distribution with coefficient of variation less than 30%. We determined grades of frontier of allowance in all derivations and in all frequency bands, in the conditions with closed eyes and with eyes open in normal control. Maximal grade for each condition was 320. In this way we appointed the standard. We recorded the EEG in patient on admission and after two months of neurorehabilitation. We did the same procedure in every patients and on the base of the standard we calculated grades. On the base of calculated grades, we determine index of asymmetry using formula (l-d)/(l+d) x 100, and make the curves. Curvilinear of this curve and extent of its declination from 0 suggest on electrophysiological stage of brain. Index of asymmetry in patients with poor long-lasting recovery is more, equal and little bit smaller on control, after two months of rehabilitation in relation to first EEG recording on admission. On the other hand in patients with good long-lasting recovery. Index of assymmetry is reduced.

A gravitino-rich universe

The gravitino may well play an important role in cosmology, not only because its interactions are Planck-suppressed and therefore long-lived, but also because it is copiously produced via various processes such as particle scatterings in thermal plasma, and (pseudo) modulus and inflaton decays. We study a possibility that the early Universe was gravitino-rich from various aspects. In particular, a viable cosmology is possible, if high-scale supersymmetry is realized in nature as suggested by the recent discovery of the standard-model like Higgs boson of mass about 125-126 GeV. We find that the Universe can be even gravitino-dominated, in which case there will be an entropy dilution by the gravitino decay. If the gravitino abundance is proportional to the reheating temperature, both the maximal baryon asymmetry in leptogenesis and the dark matter from the gravitino decay become independent of the reheating temperature. The dark matter candidate is the Wino-like neutralino, whose mass is suppressed compared to the anomaly-mediation relation.

On Application of a Probabilistic K-Nearest Neighbors Model for Cluster Validation Problem

K-Nearest Neighbors is a widely used technique for classifying and clustering data. In the current article, we address the cluster stability problem based upon probabilistic characteristics of this approach. We estimate the stability of partitions obtained from clustering pairs of samples. Partitions are presumed to be consistent if their clusters are stable. Clusters validity is quantified through the amount of K-Nearest Neighbors belonging to the point's sample. The null-hypothesis, of the well-mixed samples within the clusters, suggests Binomial Distribution of this quantity with K trials and the success probability 0.5. A cluster is represented by a summarizing index, of the p-values calculated over all cluster objects, under the null hypothesis for the alternative, and the partition quality is evaluated via the worst partition cluster. The true number of clusters is attained by the empirical index distribution having maximal suitable asymmetry. The proposed methodology offers to produce the index distributions sequentially and to assess their asymmetry. Numerical experiments exhibit a good capability of the methodology to expose the true number of clusters.

Asymmetry of Photodetachment of F− by Few-Cycle Infrared Laser Fields: Laser-Intensity Effects

Asymmetry of the photodetachment of F− by few-cycle circularly polarized infrared laser fields is studied by using a nonperturbative quantum scattering theory. The asymmetry of photoelectrons emitted to a pair of two opposite directions for low laser peak intensities is found and the dependence of the asymmetry on the laser peak intensity is investigated. It is found that the asymmetry degree varies with the carrier-envelope (CE) phase as a sine-like pattern. The asymmetry degree, the value of the maximal asymmetry degree and the value of the CE phase corresponding to the maximal asymmetry degree vary with the laser peak intensity dramatically. At higher laser intensities, the asymmetry is still distinctive for relatively-long few-cycle pulses. It provides a possible means to measure the CE phase of laser pulses at lower intensities.

Asymmetry in the Strong-field Photodetachment of H− by Linearly Polarized Few-cycle Pulses

Photodetachment of H− irradiated by linearly polarized few-cycle laser field is investigated by time-dependent Schrödinger equation numerically. The photo-electron left-right asymmetry parameter as a function of carrier-envelop (CE) phase of few-cycle pulses is attained. We confirm the asymmetry of photoelectron distribution in H− photodetachment and find that the maximal asymmetry parameter of H− is equal to that of H atom under the same conditions but the corresponding CE phases are quite different. Thus a CE phase shift appears. Compared to that of H atom and field free electron, the zero asymmetry CE phase shift is sensitively affected by Coulomb field. The Coulomb effect on the asymmetry of H− photodetachment mainly behaves in the CE phase shift of H− instead of the amplitude of asymmetry parameter curve.

Second-order direct CP asymmetry in [formula omitted

A direct CP asymmetry in inclusive semileptonic B(s) decays vanishes by CPT to lowest order in weak interactions. Calculating the asymmetry at second-order-weak interactions in the Cabibbo–Kobayashi–Maskawa framework we find Asl=(−3.2±0.9)×10−9. A maximal asymmetry which is two orders of magnitude larger is estimated in a left–right-symmetric model. This quite generic upper bound implies negligible effects on wrong-sign lepton asymmetries in B0 and Bs decays.

A nonparametric symmetry test for absolutely continuous bivariate copulas

Based on the works by Klement and Mesiar (Comment Math Univ Carolinae 47:141–148, 2006) and Nelsen (Stat Pap 48:329–336, 2007) on maximal asymmetry of copulas, we define and study the concept of tri-symmetry and we propose a simple statistic to test symmetry of a bivariate copula, given a random sample of an absolutely continuous bivariate random vector. We also make a power comparison against some other well known nonparametric symmetry tests.

Nuclear symmetry energy effects on liquid-gas phase transition in hot asymmetric nuclear matter

The liquid-gas phase transition in hot asymmetric nuclear matter is investigated within relativistic mean-field model using the density dependence of nuclear symmetry energy constrained from the measured neutron skin thickness of finite nuclei. We find symmetry energy has a significant influence on several features of liquid-gas phase transition. The boundary and area of the liquid-gas coexistence region, the maximal isospin asymmetry and the critical values of pressure and isospin asymmetry all of which systematically increase with increasing softness in the density dependence of symmetry energy. The critical temperature below which the liquid-gas mixed phase exists is found higher for a softer symmetry energy.

Computed Tomographic Validation of the Porcine Model for Thoracic Scoliosis

Computed Tomographic Analysis of the Porcine Scoliosis Model. To describe the spinal and rib cage modifications using computed tomography (CT). Optimal development of nonfusion techniques for treatment of adolescent idiopathic scoliosis (AIS) requires a reliable large animal model that achieves spinal and rib cage modifications similar to AIS. Previous work has described the global 3-dimensional nature of the progressive deformity. This IACUC-approved study includes 11 extracted scoliotic spines from a previous investigation. Scoliosis was induced through unilateral posterior ligament tethering of the spine via pedicle screw fixation, and ipsilateral rib cage tethering. CT analysis was used to quantify rib cage asymmetry, axial rotation, and wedging of the apical functional unit (2 vertebrae and intervening disc) for each specimen. The mean coronal Cobb angle was 55.7 degrees (n = 11). Vertebral and intervertebral heights of the apical functional unit demonstrated convex heights (untethered) were always larger than concave (tethered) heights (P < 0.05). Axial rotation was maximal (mean, 20 degrees ) at 1 to 2 levels distal to the coronal apex. Maximal rib cage asymmetry was demonstrated at the transverse apex with significant coupling of the rotational and rib cage modifications (r = 0.82). A large initial Cobb index (tether tension) was significantly correlated with vertebral and intervertebral wedging and coronal curve progression. The present study has used CT analysis to analyze spinal and rib cage modifications in the Porcine Scoliosis Model. Placement of a unilateral ligamentous spinal tether combined with concave rib cage ligament tethering during the rapid growth stage of the Yorkshire pig results in significant apical vertebral and intervertebral wedging and rotational and rib cage modifications. The porcine model is a reliable and duplicable model for scoliosis, which bears significant similarities to AIS.

Bilateral symmetry of radial pulse in high-level tennis players: implications for the validity of central aortic pulse wave analysis

Reconstruction of the central aortic pressure wave from the noninvasive recording of the radial pulse with applanation tonometry has become a standard tool in the field of hypertension. It is not presently known whether recording the radial pulse on the dominant or the nondominant side has any effect on such reconstruction. We carried out radial applanation tonometry on both forearms in young, healthy, male volunteers, who were either sedentary (n = 11) or high-level tennis players (n = 10). The purpose of including tennis players was to investigate individuals with extreme asymmetry between the dominant and nondominant upper limb. In the sedentary individuals, forearm circumference and handgrip strength were slightly larger on the dominant (mean +/- SD respectively 27.9 +/- 1.5 cm and 53.8 +/- 10 kg) than on nondominant side (27.3 +/- 1.6 cm, P < 0.001 vs. dominant, and 52.1 +/- 11 kg, P = NS). In the tennis players, differences between sides were more conspicuous (forearm circumference: dominant 28.0 +/- 1.7 cm nondominant 26.4 +/- 1.5 cm, P < 0.001; handgrip strength 61.4 +/- 10.8 vs. 53.4 +/- 9.7 kg, P < 0.001). We found that in both sedentary individuals and tennis players, the radial pulse had identical shape on both sides and, consequently, the reconstructed central aortic pressure waveforms, as well as derived indices of central pulsatility, were not dependent on the side where applanation tonometry was carried out. Evidence from individuals with maximal asymmetry of dominant vs. nondominant upper limb indicates that laterality of measurement is not a methodological issue for central pulse wave analysis carried out with radial applanation tonometry.

Asymmetry in Quadriceps Rate of Force Development as a Functional Outcome Measure in TKA

Quadriceps muscle strength is an important predictor of functional abilities in patients having TKA. However, because several daily activities are characterized by a limited time to generate force, it has been suggested that rate of force development (RFD) could better predict functional difficulties than maximal strength. We therefore hypothesized the side-to-side asymmetry would be larger for RFD than for maximal strength, and RFD asymmetry relates to subjective symptoms and/or functional daily living activities. We studied 31 subjects (17 women, 14 men) 6 +/- 1 months after undergoing TKA for unilateral osteoarthritis. Symptoms and limitations during activities of daily living were quantified using the knee outcome survey-activities of daily living scale (KOS-ADLS). Quadriceps maximal strength and RFD at different times (50 to 200 ms from contraction onset) were quantified during unilateral maximal voluntary isometric actions. Side-to-side asymmetries (involved versus uninvolved side) were larger for RFD (approximately 36%) than for maximal strength (approximately 24%). Subjective knee function related to all RFD asymmetry variables, but not to maximal strength asymmetry. In addition to maximal strength, quadriceps RFD in the first 100 to 200 ms from contraction onset provides an alternative functional outcome measure for individuals undergoing TKA.

Thermal rectification in nonlinear quantum circuits

We present a theoretical study of radiative heat transport in nonlinear solid-state quantum circuits. We give a detailed account of heat rectification effects, i.e., the asymmetry of heat current with respect to a reversal of the thermal gradient, in a system consisting of two reservoirs at finite temperatures coupled through a nonlinear resonator. We suggest an experimentally feasible superconducting circuit employing the Josephson nonlinearity to realize a controllable low-temperature heat rectifier with a maximal asymmetry of the order of 10%. We also discover a parameter regime where the rectification changes sign as a function of temperature.

Intensity-dependent asymmetric photoionization in few-cycle laser pulses

The asymmetric photoionization of atoms irradiated by intense, few-cycle laser pulses is studied numerically. The results show that the pulse intensity affects the asymmetric photoionization in three aspects. First, at higher intensities, the asymmetry becomes distinctive for few-cycle pulses of longer durations. Second, as the laser intensity increases, the maximal asymmetry first decreases then increases after it has reached a minimal value. Last, the value of the carrier-envelope phase corresponding to the maximal asymmetry varies with the pulse intensity. This study reveals that the increasing of pulse intensity is helpful for observing the asymmetric photoionization.

Continuous EEG Monitoring During Thrombolysis in Acute Hemispheric Stroke Patients Using the Brain Symmetry Index

Continuous EEG monitoring could benefit stroke patients as it may detect changes in brain function in a possible reversible state, allowing early intervention. The Brain Symmetry Index (BSI) was introduced previously as a measure to quantify ischemia in acute hemispheric stroke patients, and a positive correlation was found between the BSI and the National Institutes of Health Stroke Scale. Here, we explore the feasibility and potential clinical relevance of continuous EEG monitoring in acute hemispheric stroke, with the BSI as an indicator of the effect of thrombolysis with recombinant tissue plasminogen activator (r-tPA). Patients with acute hemispheric stroke treated with r-tPA were monitored using a bipolar eight channel EEG. The BSI is defined as the mean of the absolute value of the difference in the mean hemispheric amplitude spectrum; values range from 0 (no asymmetry) to 1 (maximal asymmetry). The clinical condition of the patients was assessed with the National Institutes of Health Stroke Scale. In this pilot study 16 patients were included. In all patients, the BSI remained constant or showed improvement during and after treatment with r-tPA. The correlation between the BSI and National Institutes of Health Stroke Scale in this study is significant, and confirms previous results. The correlation between the change in BSI and the change in National Institutes of Health Stroke Scale during treatment with r-tPA is significant, as well. No clinical significant complications occurred during r-tPA treatment. Our results show that continuous EEG monitoring using the BSI is technically feasible and provides real-time information about the effect of thrombolysis in acute hemispheric stroke patients.

Predicting seizure-free status for temporal lobe epilepsy patients undergoing surgery: prognostic value of quantifying maximal metabolic asymmetry extending over a specified proportion of the temporal lobe.

Conventional visual analysis of brain (18)F-FDG PET scans is useful for predicting postsurgical improvement for temporal lobe epilepsy (TLE) patients, but prognostic value for identifying patients who will achieve seizure-free status is considerably lower. We aimed to develop an approach with which to quantitatively assess prognostically pertinent aspects of metabolic asymmetry in presurgical PET scans for forecasting postsurgical seizure-free clinical outcomes. Presurgical brain PET scans of 75 TLE patients were examined using a display/analysis tool that quantified maximal metabolic asymmetry in a specified proportion (x%) of the temporal lobe pixels in the most asymmetric plane, generating a temporal lobe asymmetry index (T-AI(x)). Results of this analysis were compared with patients' actual postsurgical outcomes after an average of approximately 4 y of clinical follow-up. The investigation was divided into 2 main steps: The PET scans examined in the first step, selected by chronological order of scan acquisition dates, comprised just less than two thirds of the patient group studied (n=47) and were used to look for parameters predicting seizure-free postsurgical outcome; in the second step, the predictive value of the parameters suggested by the analysis in the first step was independently examined using the set of remaining PET scans (n=28) to check for wider applicability of the approach. Of the 75 patients studied, 42 became seizure free after surgery, whereas 33 continued to seize beyond the immediate postoperative period, during a mean 3.8-y follow-up interval. The specified proportion of temporal pixels with which to assess maximal asymmetry that provided the highest prognostic value with respect to achieving seizure-free status was 20%. Across the study population, those patients with scans having lower T-AI(20) values (corresponding to <40% difference in pixel intensities between left and right temporal lobes, among the 20% most asymmetric left-right pixel pairs measured in the most asymmetric plane) were only half as likely to continue to have seizures postsurgically as those with scans having higher T-AI(20) values (positive likelihood ratio for achieving seizure-free outcome, 1.98; 95% confidence interval, 1.07-3.67). Overall, those patients with greater maximal asymmetry, as indexed by higher T-AI(20) values, had a significantly decreased chance of achieving seizure-free status after surgery than those with lower degrees of asymmetry (P=0.017), and this same tendency was observed for both the first and second series of PET scans examined. A quantifying approach to assessing maximal temporal asymmetry over a specified proportion of the temporal lobe may help to predict whether patients will likely be free of seizures during the years after neurosurgical resection of epileptogenic tissue.

Experimental study of pedestrian counterflow in a corridor

In this work the results of a pedestrian counterflow experiment in a corridor of width 2 mare presented. 67 participants were divided into two groups with varying relative andabsolute size and walked in opposite directions through a corridor. The video footage takenfrom the experiment was evaluated for passing times, walking speeds, fluxes and laneformation, including symmetry breaking. The results include comparatively large fluxes andspeeds as well as a maximal asymmetry between left- and right-hand traffic. The sum offlow and counterflow in any case turns out to be larger than the flow in all situationswithout counterflow.

Photoionization of H atoms in few-cycle laser pulses

Photoionization of hydrogen atoms in few-cycle laser pulses is studied numerically. The total ionization probability, the instantaneous ionization probability, and the partial ionization probabilities in a pair of opposite directions are obtained. The partial ionization probabilities are not always equal to each other which is termed as inversion asymmetry. The variation of asymmetry degree with the CE phase, the pulse duration and the pulse intensity is studied. It is found that the pulse intensity affects the asymmetry degree in many aspects. Firstly, the asymmetry is more distinct at higher intensities than that at lower intensities when the pulse duration exceeds 4 cycles; secondly, the maximal asymmetry in lower intensities varies with the CE phase visibly while at higher intensities not; thirdly, the partial ionization probabilities equal to each other for some special CE phases. For lower pulse intensities, the corresponding value of CE phase is always 0.5π and 1.5π, while for higher pulse intensities, the corresponding value varies with the pulse intensity. Similar phenomena were observed in a recent experiment using few-cycle radio-frequency (RF) pulses.

Efficiency and maximal CP-asymmetry of scalar triplet leptogenesis

We study thermal leptogenesis induced by decays of a scalar SU(2)L triplet. Despite the presence of gauge interactions, unexpected features of the Boltzmann equations make the efficiency close to maximal in most of the parameter space. We derive the maximal CP asymmetry in triplet decays, assuming that it is generated by heavier sources of neutrino masses: in this case successful leptogenesis needs a triplet heavier than 2.5×1010 GeV and does not further restrict its couplings, allowing detectable μ→eγ,τ→μγ rates in the context of supersymmetric models. Triplet masses down to the TeV scale are viable in presence of extra sources of CP-violation.

Junction of Three Quantum Wires: Restoring Time-Reversal Symmetry by Interaction

We investigate the transport of correlated fermions through a junction of three one-dimensional quantum wires pierced by a magnetic flux. We determine the flow of the conductance as a function of a low-energy cutoff in the entire parameter space. For attractive interactions and generic flux the fixed point with maximal asymmetry of the conductance is the stable one, as conjectured recently. For repulsive interactions and arbitrary flux we find a line of stable fixed points with vanishing conductance as well as stable fixed points with symmetric conductance (4/9)(e(2)/h).

Leptogenesis for pedestrians

During the process of thermal leptogenesis temperature decreases by about one order of magnitude while the baryon asymmetry is generated. We present an analytical description of this process so that the dependence on the neutrino mass parameters becomes transparent. In the case of maximal CP asymmetry all decay and scattering rates in the plasma are determined by the mass M1 of the decaying heavy Majorana neutrino, the effective light neutrino mass m∼1 and the absolute mass scale m¯ of the light neutrinos. In the mass range suggested by neutrino oscillations, msol≃8×10-3eV≲m∼1≲matm≃5×10-2eV, leptogenesis is dominated just by decays and inverse decays. The effect of all other scattering processes lies within the theoretical uncertainty of present calculations. The final baryon asymmetry is dominantly produced at a temperature TB which can be about one order of magnitude below the heavy neutrino mass M1. We also derive an analytical expression for the upper bound on the light neutrino masses implied by successful leptogenesis.