Longitudinal Asymmetry Research Articles

Laboratory study of the influence of dip and ore width on gravity flow during longitudinal sublevel caving

A self-designed scaled physical draw model was used to mimic the extraction of a moderately stable and inclined medium-thick ore body. In terms of the ore dip and width, the gravity flow of the blasted ore and waste rock was investigated using tracing with labeled markers. The laboratory results indicate that the ore dip and its width have an impact on the flow axis and shape of the draw body. The flow axis was divided into two parts with lower and upper flow axes, respectively. The upper flow axis was parallel to the upper inclined wall, and the lower flow axis coincided with the axis of the draw point. The length of the upper flow axis and the area of draw body, influenced by the upper inclined wall, increased as the ore width or its dip decreased. The shape of the draw body in the lower part had longitudinal asymmetry and was similar to an inverted water drop; however, the shape of the draw body, which was influenced by the upper inclined wall, produced a variation and rotation to a certain extent, and no longer had the revolution symmetry about the central axis of the draw point. To this end, the gravity flow presented can provide a theoretical basis for ore recovery optimization.

Longitudinal Double Spin Asymmetries of π0 - Jet Correlations in Polarized Proton Collisions at s = 510 GeV at STAR

One of the primary goals of the spin physics program at STAR is to constrain the polarized gluon distribution function, [Formula: see text], by measuring the longitudinal double-spin asymmetry ([Formula: see text]) of various final-state channels. Using a jet in the mid-rapidity region [Formula: see text] correlated with an azimuthally back-to-back [Formula: see text] in the forward rapidity region [Formula: see text] provides a new possibility to access the [Formula: see text] distribution at Bjorken-[Formula: see text] down to 0.01. Compared to inclusive jet or inclusive [Formula: see text] measurements, this channel also allows to constrain the initial parton kinematics. In these proceedings, we will present the status of the analysis of the [Formula: see text]-jet [Formula: see text] in longitudinally polarized proton+proton collisions at [Formula: see text] =510 GeV with 80 pb[Formula: see text] of data taken during the 2012 RHIC run. We also compare the projected [Formula: see text] uncertainties to theoretical predictions of the [Formula: see text] by next-to-leading order (NLO) model calculations with different polarized parton distribution functions.

Cross-sectional and longitudinal voxel-based grey matter asymmetries in Huntington's disease.

Huntington's disease (HD) is a progressive neurodegenerative disorder that can be genetically confirmed with certainty decades before clinical onset. This allows the investigation of functional and structural changes in HD many years prior to disease onset, which may reveal important mechanistic insights into brain function, structure and organization in general. While regional atrophy is present at early stages of HD, it is still unclear if both hemispheres are equally affected by neurodegeneration and how the extent of asymmetry affects domain-specific functional decline. Here, we used whole-brain voxel-based analysis to investigate cross-sectional and longitudinal hemispheric asymmetries in grey matter (GM) volume in 56 manifest HD (mHD), 83 pre-manifest HD (preHD), and 80 healthy controls (HC). Furthermore, a regression analysis was used to assess the relationship between neuroanatomical asymmetries and decline in motor and cognitive measures across the disease spectrum. The cross-sectional analysis showed striatal leftward-biased GM atrophy in mHD, but not in preHD, relative to HC. Longitudinally, no net 36-month change in GM asymmetries was found in any of the groups. In the regression analysis, HD-related decline in quantitative-motor (Q-Motor) performance was linked to lower GM volume in the left superior parietal cortex. These findings suggest a stronger disease effect targeting the left hemisphere, especially in those with declining motor performance. This effect did not change over a period of three years and may indicate a compensatory role of the right hemisphere in line with recent functional imaging studies.

Monte Carlo Simulation of THz Radiation Detection in GaN MOSFET n+nn+ Channel with Uncentered Gate in n-region

Electron transport and drain current noise in the wurtzite GaN MOSFET have been studied by Monte Carlo particle simulation which simultaneously solves the Boltzmann transport and pseudo-2D Poisson equations. A proper design of GaN MOSFET n+nn+ channel with uncentered gate in n-region to reach the maximum detection sensitivity is proposed. It is shown that the main role in formation of longitudinal transport asymmetry and THz radiation detection is played by optical phonon emission process. It is found that the detection current at 300 K is maximal in frequency range from 0.5 to 7 THz. At higher frequenciea the detection current rapidly decreases due to the inertia of electron motion.

Double-longitudinal spin asymmetry in single-inclusive lepton scattering at NLO

We calculate the double-spin asymmetries $A_{\mathrm{LL}}$ for the processes $\ell N\to h X$ and $\ell N\to {\mathrm{jet}}\, X$ at next-to-leading order accuracy in perturbative QCD. We compare our theoretical results for $A_{\mathrm{LL}}$ to data from the SLAC E155 experiment, finding only partially satisfactory agreement. We conclude that measurements of $A_{\mathrm{LL}}$ and the relevant polarized and unpolarized cross sections should be performed at the present-day fixed-target lepton scattering experiments, as well as at a future electron ion collider, in order to verify our understanding of this process. We present predictions of the longitudinal double-spin asymmetries for these experiments.

Gluon orbital angular momentum at small x

We present a general analysis of the orbital angular momentum (OAM) distribution of gluons ${L}_{g}(x)$ inside the nucleon with particular emphasis on the small-$x$ region. We derive a novel operator representation of ${L}_{g}(x)$ in terms of Wilson lines and argue that it is approximately proportional to the gluon helicity distribution ${L}_{g}(x)\ensuremath{\approx}\ensuremath{-}2\mathrm{\ensuremath{\Delta}}G(x)$ at small $x$. We also compute longitudinal single-spin asymmetry in exclusive diffractive dijet production in lepton-nucleon scattering in the next-to-eikonal approximation and show that the asymmetry is a direct probe of the gluon helicity/OAM distribution as well as the QCD odderon exchange.

Асимметрия рельсовых цепей с реле ДСШ-2

Objective: To consider the causes and ways to reduce voltage sags on resonant track relays of track circuits with dssh-2 relays. Methods: Analysis of voltage depressions causes on a track relay with track circuit, free of rolling stock on rails, was carried out by means of natural experiments with oscillography and voltage on a track relay analysis, as well as measurement of insulation resistance of rail lines and the inductances of the main windings of transformers. Results: It was determined that one of the causes of voltage depressions on road relays were the transverse asymmetry of the resistance of rail lines caused by metal chips generated by pantograph trains when passing a nonoverlayable interval on the approach to the station. The impact of longitudinal spin asymmetry of rail line resistance on voltage sags, which is formed by a variation in inductance of the primary winding sections of an impedance bond. The relationship of voltage sags and the methods of rolling stock handling as well as places of electric power cut-offs’ was studied. Practical importance: The rule of connecting the main windings of transformers to the rails of sections was proposed, in order to reduce the impact of the variation in total inductance of transformers’ sections on the longitudinal asymmetry of rail line resistance. The conducted research made it possible to determine the causes and ways to reduce voltage dips on the resonant track relays of track circuits with dssh-2 relays.

Hunting the Gluon Orbital Angular Momentum at the Electron-Ion Collider.

Applying the connection between the parton Wigner distribution and orbital angular momentum (OAM), we investigate the probe of the gluon OAM in hard scattering processes at the planned electron-ion collider. We show that the single longitudinal target-spin asymmetry in the hard diffractive dijet production is very sensitive to the gluon OAM distribution. The associated spin asymmetry leads to a characteristic azimuthal angular correlation of sin(ϕ_{q}-ϕ_{Δ}), where ϕ_{Δ} and ϕ_{q} are the azimuthal angles of the proton momentum transfer and the relative transverse momentum between the quark-antiquark pair. This study may motivate a first measurement of the gluon OAM in the proton spin sum rule.

Measurement of the cross section and longitudinal double-spin asymmetry for dijet production in polarized pp collisions at s=200 GeV

We report the first measurement of the longitudinal double-spin asymmetry $A_{LL}$ for mid-rapidity di-jet production in polarized $pp$ collisions at a center-of-mass energy of $\sqrt{s} = 200$ GeV. The di-jet cross section was measured and is shown to be consistent with next-to-leading order (NLO) perturbative QCD predictions. $A_{LL}$ results are presented for two distinct topologies, defined by the jet pseudorapidities, and are compared to predictions from several recent NLO global analyses. The measured asymmetries, the first such correlation measurements, support those analyses that find positive gluon polarization at the level of roughly 0.2 over the region of Bjorken-$x > 0.05$.

Leading-order determination of the gluon polarisation from semi-inclusive deep inelastic scattering data

Using a novel analysis technique, the gluon polarisation in the nucleon is re-evaluated using the longitudinal double-spin asymmetry measured in the cross section of semi-inclusive single-hadron muoproduction with photon virtuality Q^2>1~(mathrm{GeV}/c)^2. The data were obtained by the COMPASS experiment at CERN using a 160 GeV/c polarised muon beam impinging on a polarised ^6LiD target. By analysing the full range in hadron transverse momentum p_mathrm{T}, the different p_mathrm{T}-dependences of the underlying processes are separated using a neural-network approach. In the absence of pQCD calculations at next-to-leading order in the selected kinematic domain, the gluon polarisation Delta g/g is evaluated at leading order in pQCD at a hard scale of mu ^2= langle Q^2 rangle = 3 (mathrm{GeV}/c)^2. It is determined in three intervals of the nucleon momentum fraction carried by gluons, x_mathrm{g}, covering the range 0.04 !<! x_{ mathrm g}! <! 0.28 and does not exhibit a significant dependence on x_mathrm{g}. The average over the three intervals, langle Delta g/g rangle = 0.113 pm 0.038_mathrm{(stat.)}pm 0.036_mathrm{(syst.)} at langle x_mathrm{g} rangle approx 0.10, suggests that the gluon polarisation is positive in the measured x_mathrm{g} range.

Measuring (subglacial) bedform orientation, length, and longitudinal asymmetry – Method assessment

Geospatial analysis software provides a range of tools that can be used to measure landform morphometry. Often, a metric can be computed with different techniques that may give different results. This study is an assessment of 5 different methods for measuring longitudinal, or streamlined, subglacial bedform morphometry: orientation, length and longitudinal asymmetry, all of which require defining a longitudinal axis. The methods use the standard deviational ellipse (not previously applied in this context), the longest straight line fitting inside the bedform footprint (2 approaches), the minimum-size footprint-bounding rectangle, and Euler’s approximation. We assess how well these methods replicate morphometric data derived from a manually mapped (visually interpreted) longitudinal axis, which, though subjective, is the most typically used reference. A dataset of 100 subglacial bedforms covering the size and shape range of those in the Puget Lowland, Washington, USA is used. For bedforms with elongation > 5, deviations from the reference values are negligible for all methods but Euler’s approximation (length). For bedforms with elongation < 5, most methods had small mean absolute error (MAE) and median absolute deviation (MAD) for all morphometrics and thus can be confidently used to characterize the central tendencies of their distributions. However, some methods are better than others. The least precise methods are the ones based on the longest straight line and Euler’s approximation; using these for statistical dispersion analysis is discouraged. Because the standard deviational ellipse method is relatively shape invariant and closely replicates the reference values, it is the recommended method. Speculatively, this study may also apply to negative-relief, and fluvial and aeolian bedforms.

Broadside Dual-Channel Orthogonal-Polarization Radiation Using a Double-Asymmetric Periodic Leaky-Wave Antenna

The paper demonstrates that double unit-cell asymmetry in periodic leaky-wave antennas (P-LWAs), i.e. asymmetry with respect to both the longitudinal and transversal axes of the structure -- or longitudinal asymmetry (LA) and transversal asymmetry (TA) -- allows for the simultaneous broadside radiation of two orthogonal modes excited at the two ports of the antenna. This means that the antenna may simultaneously support two orthogonal channels, which represents an interesting polarization diversity characteristics for wireless communications. The double asymmetric (DA) unit cell combines a circularly polarized LA unit cell and a coupled mode TA unit cell, where the former provides equal radiation in the series and shunt modes while the latter separates these two modes in terms of their excitation ports. It is also shown that the degree of TA in the DA unit cell controls the cross-polarization discrimination level. The DA P-LWA concept is illustrated by two examples, a series-fed line-connected patch (SF-LCP) P-LWA and a series-fed capacitively-coupled patch (SF-CCP) P-LWA, via full-wave simulation and also experiment for the SF-LCP P-LWA case.

Confirmation of the upside-down drop shape theory in gravity flow and development of a new empirical equation to calculate the shape

Understanding the flow rules of caved ore and rock is the foundation for efficiently applying the caving mining method, and studying the change trends in both extraction zone (EZ) and movement zone (MZ) is the basis for researching these rules and for optimizing structural parameters. Ellipsoid draw theory is one of the traditional theories for the shapes of the extraction zone and the movement zone, which has played an important role in investigating the draw problems in caving mining method for a very long time. The isolated draw tests conducted in this study confirmed the upside-down drop shape theory's prediction that the EZ's shape has obvious longitudinal asymmetry, and is not a standard ellipsoid. The MZ's shape was further studied according to model experiments conducted by Castro, resulting in the fact that the MZ's shape is also the upside down drop shape. On this basis, a new way was proposed to investigate the extraction zone and movement zone shapes and their change trends, and then new empirical equations were deduced for calculation of their shapes.

Nucleon structure functions and longitudinal spin asymmetries

The chiral constituent quark model (χ CQM) has been used to analyse the phenomenological dependence of the spin independent (F 1 p, n and F 2 p, n ) and the spin dependent (g 2 p, n ) structure functions of the nucleon on the the Bjorken scaling variable x . The implication of the presence of the sea quarks has been discussed for the p and n longitudinal spin asymmetries (A 1 p (x ) and A 1 n (x ) ratio of polarized to unpolarized quark distribution functions for up and down quarks in the p and n , , , and . The results have been compared with the recent available experimental observations.

Longitudinal asymmetry and proton spin rotation in p⃗d scattering with pionless effective field theory

The energy dependence of the longitudinal asymmetry $({A}_{L})$ and the spin rotation of the proton on the deuterium target in the $\stackrel{P\vec}{p}d$ scattering are presented using the pionless effective field theory formalism. The strong, weak, and Coulomb interactions have been introduced in the $\stackrel{P\vec}{p}d$ scattering. We have shown that in the presence of Coulomb interaction, the parity-conserving (PC) and the parity-violating (PV) sectors are modified. The PV two-body transitions diagrams have been evaluated with the inclusion of Coulomb interaction and consequently the PV observables are enhanced. The leading-order values of the ${A}_{L}$ and the spin rotation of the proton on the deuterium target are calculated at the proton laboratory energies above 0.7 MeV, in order to calculate the Coulomb effect perturbatively, up to 3 MeV where typical momenta is $Q\ensuremath{\ll}{m}_{\ensuremath{\pi}}$. With the lack of experimental data for the low-energy coupling constants (LECs), we have used two estimated sets for the five independent (PV) LECs of the weak $NN$ PV Lagrangian. The order of magnitude, of the PV observables with these two sets, is found to be ${10}^{\ensuremath{-}6}$ to ${10}^{\ensuremath{-}7}$ which indicates that the expected order is achieved in this energy range. The cutoff independent results support the validity of our approach.

Conjugate hemisphere ionospheric response to the St. Patrick's Day storms of 2013 and 2015 in the 100°E longitude sector

AbstractThe effects of the St. Patrick's Day geomagnetic storms of 2013 and 2015 in the equatorial and low‐latitude regions of both hemispheres in the 100°E longitude sector is investigated and compared with the response in the Indian sector at 77°E. The data from a chain of ionosondes and GPS/Global Navigation Satellite Systems receivers at magnetic conjugate locations in the 100°E sector have been used. The perturbation in the equatorial zonal electric field due to the prompt penetration of the magnetospheric convective under shielded electric field and the over shielding electric field gives rise to rapid fluctuations in the F2 layer parameters. The direction of IMF Bz and disturbance electric field perturbations in the sunset/sunrise period is found to play a crucial role in deciding the extent of prereversal enhancement which in turn affect the irregularity formation (equatorial spread F) in the equatorial region. The northward (southward) IMF Bz in the sunset period inhibited (supported) the irregularity formation in 2015 (2013) in the 100°E sector. Large height increase (hmF2) during sunrise produced short‐duration irregularities during both the storms. The westward disturbance electric field on 18 March inhibited the equatorial ionization anomaly causing negative (positive) storm effect in low latitude (equatorial) region. The negative effect was amplified in low midlatitude by disturbed thermospheric composition which produced severe density/total electron content depletion. The longitudinal and hemispheric asymmetry of storm response is observed and attributed to electrodynamic and thermospheric differences.

Whole-brain analysis reveals increased neuroanatomical asymmetries in dementia for hippocampus and amygdala.

Structural magnetic resonance imaging data are frequently analysed to reveal morphological changes of the human brain in dementia. Most contemporary imaging biomarkers are scalar values, such as the volume of a structure, and may miss the localized morphological variation of early presymptomatic disease progression. Neuroanatomical shape descriptors, however, can represent complex geometric information of individual anatomical regions and may demonstrate increased sensitivity in association studies. Yet, they remain largely unexplored. In this article, we introduce a novel technique to study shape asymmetries of neuroanatomical structures across subcortical and cortical brain regions. We demonstrate that neurodegeneration of subcortical structures in Alzheimer's disease is not symmetric. The hippocampus shows a significant increase in asymmetry longitudinally and both hippocampus and amygdala show a significantly higher asymmetry cross-sectionally concurrent with disease severity above and beyond an ageing effect. Our results further suggest that the asymmetry in these structures is undirectional and that primarily the anterior hippocampus becomes asymmetric. Based on longitudinal asymmetry measures we subsequently study the progression from mild cognitive impairment to dementia, demonstrating that shape asymmetry in hippocampus, amygdala, caudate and cortex is predictive of disease onset. The same analyses on scalar volume measurements did not produce any significant results, indicating that shape asymmetries, potentially induced by morphometric changes in subnuclei, rather than size asymmetries are associated with disease progression and can yield a powerful imaging biomarker for the early presymptomatic classification and prediction of Alzheimer's disease. Because literature has focused on contralateral volume differences, subcortical disease lateralization may have been overlooked thus far.

Longitudinal Asymmetry and its Measurable Effects in Pb–Pb Collisions at 2.76 TeV

Collisions of identical nuclei at finite impact parameter have an unequal number of participating nucleons from each nucleus due to fluctuations. The event-by-event fluctuations have been estimated by measuring the difference of energy in the zero-degree calorimeters on either side of interaction vertex. The fluctuations affect the global variables such as the rapidity distributions, and the effect has been correlated with a measure of these fluctuations.

Impact of Longitudinal Lesion Geometry on Location of Plaque Rupture and Clinical Presentations

ObjectivesThis study sought to investigate the impact of longitudinal lesion geometry on the location of plaque rupture and clinical presentation and its mechanism. BackgroundThe relationships among lesion geometry, external hemodynamic forces acting on the plaque, location of plaque rupture, and clinical presentation have not been comprehensively investigated. MethodsThis study enrolled 125 patients with plaque rupture documented by intravascular ultrasound. Longitudinal locations of plaque rupture were identified and categorized by intravascular ultrasound. Patients’ clinical presentations and TIMI (Thrombolysis In Myocardial Infarction) flow grade in an initial angiogram were compared according to the location of plaque rupture. Longitudinal lesion asymmetry was quantitatively assessed by the luminal radius change over the segment length (radius gradient [RG]). Lesions with a steeper radius change in the upstream segment compared with the downstream segment (RGupstream > RGdownstream) were defined as upstream-dominant lesions. ResultsOn the basis of the site of maximum rupture aperture, 56.0%, 16.0%, and 28.0% of the patients had upstream, minimal lumen area, and downstream rupture, respectively. Patients with upstream rupture more frequently presented with ST-segment elevation myocardial infarction (45.7%, 40.0%, 22.9%; p = 0.030) and with TIMI flow grade <3 (32.9%, 20.0%, 17.1%; p = 0.042). According to the ratio of upstream and downstream RG, 69.5% of lesions were classified as upstream-dominant lesions, and 30.5% were classified as downstream-dominant lesions. Among the 66 upstream-dominant lesions, 65 cases (98.5%) had upstream rupture, and the RG ratio (RGupstream/RGdownstream) was an independent predictor of upstream rupture (odds ratio: 1.481; 95% confidence interval: 1.035 to 2.120; p = 0.032). Upstream-dominant lesions more frequently manifested with ST-segment elevation myocardial infarction than did downstream-dominant lesions (48.5% vs. 24.1%; p = 0.026). ConclusionsBoth clinical presentation and degree of flow limitation were associated with the location of plaque rupture. Longitudinal lesion asymmetry assessed by RG, which can affect regional distribution of hemodynamic stress, was associated with the location of rupture and with clinical presentation.

On the east–west longitudinally asymmetric distribution of solar proton events

A large data set of 78 solar proton events observed near the Earth's orbit during 1996-2011 is investigated. An East-West longitudinal (azimuthal) asymmetry is found to exist in the distribution of flare sources of solar proton events. With the same longitudinal separation between the flare sources and the magnetic field line footpoint of observer, the number of the solar proton events originating from solar sources located on the eastern side of the nominal magnetic footpoint of observer is larger than the number of the solar proton events from solar sources located on the western side. We emphasize the importance of this statistical investigation in two aspects. On the one hand, this statistical finding confirms our previous simulation results obtained by numerically solving five-dimensional Fokker-Planck equation of solar energetic particle (SEP) transport. On the other hand, the East-West longitudinally (azimuthally) asymmetric distribution of solar proton events accumulated over a long time period provides an observational evidence for the effects of perpendicular diffusion on the SEP propagation in the heliosphere. We further point out that, in the sense of perpendicular diffusion, our numerical simulations and statistical results of SEP events confirm each other. We discuss in detail the important effects of perpendicular diffusion on the formation of the East-West azimuthal (longitudinal) asymmetry of SEP distribution in two physical scenarios, i.e., 'multiple SEP events with one spacecraft' and 'one SEP event with multiple spacecraft'. A functional relation I_{max}(r)=kr^{-1.7} quantifying the radial dependence of SEP peak intensities is obtained and utilized in the analysis of physical mechanism. The relationship between our results and those of Dresing et al. is also discussed.