Distribution Of Axes Research Articles

Study on the bending behavior of CFRP-confined square concrete-filled steel tubes reinforced with internal latticed steel angles

The bending mechanical properties of FRP-confined square concrete-filled steel tubes (CFST) reinforced with internal latticed steel angles, including the failure modes, characteristic curves and characteristic mechanical parameters of tested specimens, were investigated through experiments in this paper. The bending mechanisms were also analyzed using an established finite element model, including the analysis of the bending moment borne by each component, the distributions of contact pressure between different components at the mid-span section, and the distributions of the neutral axis under the bending capacity. The key influential parameters, including the tensile strength and thickness of the FRP, were also examined. The results indicate that the FRP has almost no influence on bending stiffness, however, it enhances the yield bending moment and bending capacity to a certain extent. It was also found that the enhancement decreases as the width of steel tube increases, and the influence of FRP is more profound before reaching the peak load. The calculation formulas for the bending capacity were developed using the superposition method and numerical fitting method. Analysis of their accuracy shows that the formulation using the superposition method yields relatively accurate and safe prediction results, with the prediction errors of less than 20 %.

On Binary Formation from Three Initially Unbound Bodies

We explore three-body binary formation (3BBF), the formation of a bound system via gravitational scattering of three initially unbound bodies (3UB), using direct numerical integrations. For the first time, we consider systems with unequal masses, as well as finite-size and post-Newtonian effects. Our analytically derived encounter rates and numerical scattering results reproduce the 3BBF rate predicted by Goodman & Hut for hard binaries in dense star clusters. We find that 3BBF occurs overwhelmingly through nonresonant encounters and that the two most-massive bodies are never the most likely to bind. Instead, 3BBF favors pairing the two least-massive bodies (for wide binaries) or the most- plus least-massive bodies (for hard binaries). 3BBF overwhelmingly favors wide-binary formation with superthermal eccentricities, perhaps helping to explain the eccentric wide binaries observed by Gaia. Hard-binary formation is far rarer, but with a thermal eccentricity distribution. The semimajor axis distribution scales cumulatively as a 3 for hard and slightly wider binaries. Although mergers are rare between black holes when including relativistic effects, direct collisions occur frequently between main-sequence stars—more often than hard 3BBF. Yet, these collisions do not significantly suppress hard 3BBF at the low-velocity dispersions typical of open or globular clusters. Energy dissipation through gravitational radiation leads to a small probability of a bound, hierarchical triple system forming directly from 3UB.

Counterpropagating optical solitary waves in orientation-modulated nematic liquid crystals

We investigate counterpropagating optical solitary waves – nematicons – in non-homogeneously oriented nematic liquid crystals. A non-symmetric angular distribution of the optic axis versus beam propagation provides the solitons with direction-dependent trajectories. By performing numerical experiments in realistic planar samples, we launch nematicons in opposite directions and examine the resulting non-specular transmission in terms of optical nonreciprocity and isolation.

Immune profiling of mouse lung adenocarcinoma paraffin tissues using multiplex immunofluorescence panel: a pilot study

BackgroundImmune profiling has become an important tool for identifying predictive, prognostic and response biomarkers for immune checkpoint inhibitors from tumor microenvironment (TME). We aimed to build a multiplex immunofluorescence (mIF) panel to apply to formalin-fixed and paraffin-embedded tissues in mice tumors and to explore the programmed cell death protein 1/ programmed cell death 1 ligand 1 (PD-1/PD-L1) axis.ResultsAn automated eight-color mIF panel was evaluated to study the TME using seven antibodies, including cytokeratin 19, CD3e, CD8a, CD4, PD-1, PD-L1, F4-80 and DAPI, then was applied in six mice lung adenocarcinoma samples. Cell phenotypes were quantified by software to explore the co-localization and spatial distribution between immune cells within the TME. This mice panel was successfully optimized and applied to a small cohort of mice lung adenocarcinoma cases. Image analysis showed a sparse degree of immune cell expression pattern in this cohort. From the spatial analysis we found that T cells and macrophages expressing PD-L1 were close to the malignant cells and other immune cells.ConclusionsComprehensive immune profiling using mIF in translational studies improves our ability to correlate the PD-1/PD-L1 axis and spatial distribution of lymphocytes and macrophages in mouse lung cancer cells to provide new cues for immunotherapy, that can be translated to human tumors for cancer intervention.

How Does Nodular Chromite Nucleate and Grow? An Integrated Microstructural and Petrological Approach

Abstract Nodular chromite ore deposits are found in ophiolites and crop out in structures interpreted as former dykes. Most of them are transposed parallel to the plastic foliation of the host peridotite. Many studies have been conducted in order to decipher the origin and evolution of nodular chromite but the outstanding lack of consensus paves the way for an integrated field, geochemical and microstructural approach to be carried out. We sampled the well-characterized Maqsad chromitite dyke that crops out at the top of the mantle–crust dunitic transition zone in the Oman ophiolite and that was not affected by transposition. The spectacular variations in nodule size and texture and their distribution within the dyke have been perfectly preserved which is a rather unique situation. We selected about 40 nodules representative of the shapes and size variability of this ore deposit. Nodules have been classified in three categories: Type-1 nodules are large skeletal chromite grains associated with amphibole and olivine filling their former porosity; Type-3 nodules have a central nucleus of chromite/silicate surrounded by a mantle of close-packed chromite grains. Their shape is best described as almond-like, and they may reach 3 cm in length; Type-2 includes all of the intermediate nodules shapes and sizes between type-1 and type-3 varieties. Electron Probe MicroAnalyser (EPMA) transects and maps show that mineral chemical variations in type-1 nodules and in the nuclei of type-2 and type-3 nodules record out of equilibrium crystal growth. They exhibit high XCr and relatively low-TiO2 and likely resulted from transient interactions between hydrothermal fluids and basaltic melts. Contrary to type-1 and nuclei, the mantles of type-2 and -3 nodules have lower Cr2O3 contents, decreasing toward the nodule edges. They are richer in TiO2 than type-1 nodules but concentration patterns of this element along edge to edge transects are quite variable. The chromite mantles of type-2 and -3 are best understood as the fractional crystallization products of a parent melt of type-1 nodules in different pFluids and/or redox conditions. The analysis of the distribution of the misorientation axis between the skeletal grains and the adjacent chromite grains in the mantle (N = 222 in 28 nodules) revealed a clustering around a [111] axis across the whole range of misorientation angles. Accordingly, we suggest that the growth of the Maqsad nodules is achieved by accretion of finer euhedral chromite grains onto a skeletal chromite grain by juxtaposition of their flat crystal facets. Combined EDS-EBSD mapping together with EPMA transects revealed that a ~1-mm-thick rim of high XCr, displaying a homothetic shape to its corresponding nuclei, is a common feature in the mantle when the nodule sizes exceed about 1 cm. We interpret this observation as the result of the accretion of grains with higher XCr compositions during the nodule construction. Overall, our new study of the Maqsad nodular chromitite highlights the peculiar and transient conditions needed to give rise to the textural and chemical complexity that is preserved in these enigmatic rocks.

Two-dimensional rheo-optical measurement system to study dynamics and structure of complex fluids

Abstract We have developed a novel rheo-optical measurement system based on two-dimensional polarization analysis, which can evaluate the rheological properties and structure of a complex fluid simultaneously. To assess the utility of the system, we used it to investigate the relationship between yield behavior and structural evolution in a TEMPO-oxidized cellulose nanofiber (T-CNF) suspension, which is a yield-stress fluid that has been actively studied in recent years. To analyze the structural evolution of a T-CNF suspension, stress-ramp tests were conducted. A two-step yield behavior was observed, and distributions of retardation and orientation axis varied dramatically with increasing shear stress. In particular, different distributions were observed in the three regions: after the first yield point, before the second yield point, and after the second yield point. In experiments with a low-concentration T-CNF suspension that exhibits no yield behavior, the retardation increased monotonically with increasing shear stress, and its distribution was uniform. It was demonstrated that the yield behavior and related structures can be analyzed from these results. More detailed structural mechanisms require various rheological tests using the developed system. However, the present insights demonstrate the valuable information provided by the developed rheo-optical measurement system, contributing essential knowledge for applications in various fields.

Physico-chemical parameters, heavy-metals and soil particle distribution of Liverpool axis of Badagry Creek, Lagos, South-western Nigeria

Heavy metal pollution is a serious issue of concern worldwide because it can bioaccumulate in aquatic organisms and transferred through the food chain to harm humans. Information on the heavy metal pollution of aquatic ecosystems is essential to protect life. Therefore, this study was undertaken to determine the physico-chemical parameters of surface water, soil particle distribution (SPD) and heavy metals in two shellfish species in Liverpool axis of Badagry Creek, Lagos State, Nigeria. Twelve physico-chemical parameters and four heavy metals were studied using standard methods. The results showed that maximum temperature was 31.0±1.00˚0C; turbidity, 118.00±50.90NTU; dissolved oxygen (DO), 13.3±3.8mg/l; dissolved carbon dioxide (COD), 67.7±19.1mg/l; total hardness, 173.0±63.1mg/l; conductivity, 39.2±12.2μS/cm and chloride was 2.0±0.7mg/l. Water quality parameters showed significant spatial variations (p<0.05) among sample stations. Pearson’s correction matrices revealed high correlation of DO with nitrate (r = 0.61), total hardness (r=0.62) and COD (r=0.52) at p<0.05. The heavy metal concentrations (mg/kg) in the shellfishes, Callinectes pallidus and Farfantepenaeus notialis were: lead, 0.05±0.05 and 0.04±0.02; copper, 2.03±0.17 and 0.84±0.18; zinc, 3.51±0.44 and 1.99±0.2 and cadmium, 0.02±0.02 and 0.03±0.04 respectively. These levels were not above the WHO standards (for heavy metals in fish and shell fish). The sediment particle distribution (SPD) showed that Liverpool Jetty had 19.05% coarse sand and 43.91% fine sand, while Apapa Jetty had the highest amount of clay 45.29% in the environment. Heavy metals in shellfishes were above the WHO standards.

Study on anisotropy orientation due to well-ordered fibrous biological microstructures.

Most biological fibrous tissues have anisotropic optical characteristics, which originate from scattering by their fibrous microstructures and birefringence of biological macromolecules. The orientation-related anisotropic interpretation is of great value in biological tissue characterization and pathological diagnosis. We focus on intrinsic birefringence and form birefringence in biological tissue samples. By observing and comparing the forward Mueller matrix of typical samples, we can understand the interpretation ability of orientation-related polarization parameters and further distinguish the sources and trends of anisotropy in tissues. For glass fiber, silk fiber, skeletal muscle, and tendon, we construct a forward measuring device to obtain the Mueller matrix image and calculate the anisotropic parameters related to orientation. The statistical analysis method based on polar coordinates can effectively analyze the difference in anisotropic parameters. For those birefringent fibers, the statistical distribution of fast-axis values derived from Mueller matrix polar decomposition was found to exhibit bimodal characteristics, which is a key point in distinguishing the single-layer birefringent fiber sample from a layered, multioriented fibrous sample. The application conditions and interference factors of anisotropic orientation parameters are analyzed. Based on the parameters extracted from the orientation bimodal distribution, we can evaluate the relative change trend of intrinsic birefringence and form birefringence in anisotropic samples. The cross-vertical bimodal distribution of the fast axis of anisotropic fibers is beneficial to accurately analyze the anisotropic changes in biological tissues. The results imply the potential of anisotropic orientation analysis for applications in pathological diagnosis.

The Orbital Structure and Selection Effects of the Galactic Center S-star Cluster

The orbital distribution of the S-star cluster surrounding the supermassive black hole in the center of the Milky Way is analyzed. A tight dependence of the pericenter distance r p on orbital eccentricity e ⋆ is found, log(rp)∼(1−e⋆) , which cannot be explained simply by a random distribution of semimajor axis and eccentricities. No stars are found in the region with high e ⋆ and large log(rp) or in the region with low e ⋆ and small log(rp) . Although the sample is still small, the G-clouds show a very similar distribution. The likelihood P(log(rp),(1−e⋆)) to determine the orbital parameters of S-stars is determined. P is very small for stars with large e ⋆ and large log(rp) . S-stars might exist in this region. To determine their orbital parameters, one however needs observations over a longer time period. On the other hand, if stars would exist in the region of low log(rp) and small e ⋆, their orbital parameters should by now have been determined. That this region is unpopulated therefore indicates that no S-stars exist with these orbital characteristics, providing constraints for their formation. We call this region, defined by log(rp/AU)<1.57+2.6(1−e⋆) , the zone of avoidance. Finally, it is shown that the observed frequency of eccentricities and pericenter distances is consistent with a random sampling of log(rp) and e ⋆ if one takes into account the fact that no stars exist in the zone of avoidance and that orbital parameters cannot yet be determined for stars with large r p and large e ⋆.

The Piluo Paleolithic site in Daocheng, Sichuan

Abstract The Piluo site, located on the southeastern edge of the Qinghai-Tibet Plateau, underwent excavation and systematic survey from April to November 2021. The work was a joint effort between the Sichuan Institute of Cultural Relics and Archaeology and the School of Archaeology and Museology at Peking University. The excavation revealed seven cultural strata that had been deposited continuously since the late Middle Pleistocene. Tens of thousands of lithics, including typical hand axes, were discovered, along with many remains of Paleolithic Age cultural activities such as residential floors created by prehistoric populations. These findings provide valuable data for investigating issues such as early human evolution in the Qinghai-Tibet Plateau, as well as the distribution, origin, and development of East Asian hand axes.

Exoplanets around Red Giants: Distribution and Habitability

As the search for exoplanets continues, more are being discovered orbiting Red Giant stars. We use current data from the NASA Exoplanet Archive to investigate planet distribution around Red Giant stars and their presence in the host’s habitable zone. As well, we explore the distribution of planet mass and orbital semi major axis for evolved stars with increasing stellar radii. From the distance distribution of the planets, we found evidence of engulfment during the post-Main Sequence evolution of the star. We found 9 Red Giant-hosted exoplanets, and 21 Subgiant-hosted exoplanets to be in the optimistically calculated habitable zone, 5 and 17 of which are in a more conservatively calculated habitable zone. All the planets detected within their habitable zone orbit stars that are in early stages of evolution. We believe that with more powerful instrumentation, more habitable planets may be found around stars that are in later stages of evolution.

Critical assessment of the recent report on the gigaparsec-scale correlation of the orientations of large quasar groups

ABSTRACT Recently, it was reported that large quasar groups (LQGs) identified from the Sloan Digital Sky Survey (SDSS) data release seven catalogue are not randomly oriented but preferentially aligned or orthogonal over scales 1–2 Gpc. To confirm this claim, I reproduced the same LQG sample and performed Sobolev tests of uniformity on the LQG orientation axes in the redshift space. Contrary to the original report based on the bimodal distribution of the LQG position angles in the sky, I found no departure from uniformity in the distribution of the LQG orientation axes. I also examined whether the LQGs are physical structures using a statistically more reliable data set constructed from the SDSS data release 16 (DR16) large-scale structure (LSS) quasar catalogue. Considering the Gaussian primordial density fluctuations and shot noise, I estimated the mass density contrasts of the LQGs from the number counts of the DR16 LSS quasars and found that most of the LQGs do not trace statistically significant high-density regions. I conclude that the LQG sample is a collection of unphysical chance associations and should not be used for any cosmological studies.

Intra-grain orientation distributions in deformed aluminium: Synchrotron X-ray diffraction experiment and crystal-plasticity finite-element simulation

The development of intra-grain orientation distributions is analyzed for 446 individual grains of an aluminium polycrystal deformed in tension to successive strains of 1, 1.5, 2, 2.5 and 4.5%. In the experiment, diffraction contrast tomography (DCT) and far-field 3D X-ray diffraction microscopy (3DXRD) were used, and a reduced-order representation of the intra-grain orientation distributions was determined from the broadening of the 3DXRD diffraction spots. A high-resolution finite-element simulation (700 elements/grain on average) was conducted on the same polycrystal, providing detailed information on orientation evolution. Several metrics were considered to analyze the experimental and simulated orientation distributions, including the average disorientation angles and the preferential disorientation axes. The average disorientation angles were found to increase almost linearly with strain, and to be in appreciable correlation between experiment and simulation (albeit evolving faster in simulation). It was shown that the preferential disorientation axes are distributed perpendicular to the tensile direction (Z) and perpendicular to the X–Y component of the Rodrigues orientation vector. Detailed crystal plasticity analyses showed that the distribution of preferential disorientation axes is related to the presence of larger slip variabilities on particular slip systems. Using a simplified approach, it was shown that accurate knowledge of the average stress of a grain is necessary in order to predict the preferential disorientation axis, which is well-captured by the finite-element simulation. The intra-grain stress distribution appears to have comparatively less influence.

Multiples among B stars in the Scorpius-Centaurus association

Context. The frequency, semi-major axis, and mass distribution of stellar companions likely depend on the mass of the primaries and on the environment where the stars form. These properties are very different for early- and late-type stars. However, data are largely incomplete, even for the closest environments to the Sun, preventing a cleaner view of the problem. Aims. This paper provides basic information about the properties of companions to B stars in the Scorpius-Centaurus association (age ∼ 15 Myr); this is the closest association containing a large population of 181 B-stars. Methods. We gathered available data combining high contrast imaging samples from BEAST, SHINE, and previous surveys with evidence of companions from Gaia (both through direct detection and astrometry), from eclipsing binaries, and from spectroscopy. We evaluated the completeness of the binary search and estimated the mass and semi-major axis for all detected companions. These data provide a complete sample of stellar secondaries (extending well in the substellar regime) for separation&gt; 3 au, and they are highly informative as to closer companions. Results. We found evidence for 200 companions around 181 stars. We did not find evidence for companions for only 43 (23.8 ± 3.6%) of the targets, with the fraction being as low as 15.2 ± 4.1% for stars with MA &gt; 3.5 M⊙ while it is 31.5 ± 5.9% for lower-mass stars. This confirms earlier findings for a clear trend of a binary fraction with stellar mass. The median semi-major axis of the orbits of the companions is smaller for B than in A stars, confirming a turn-over previously found for OB stars. The mass distribution of the very wide (a &gt; 1000 au) and closer companions is different. Very few companions of massive stars MA &gt; 5.0 M⊙ have a mass below solar and even fewer are M stars with a semi-major axis &lt; 1000 au. However, the scarcity of low-mass companions extends throughout the whole sample. Period and mass ratio distributions are different for early B stars (up to B7 spectral type) and stars of a later spectral type: most early B stars are in compact systems with massive secondaries, while less massive stars are mainly in wider systems with a larger spread in mass ratios. We derived log-normal fits to the distribution of the semi-major axis and mass ratios for low and high-mass B stars; these relations suggest that it is not probable that the planets and brown dwarf (BD) companions to b Cen and μ2 Sco are extreme cases in the distribution of stellar companions. Conclusions. We interpret our results as the formation of secondaries with a semi-major axis &lt; 1000 au (about 80% of the total) by fragmentation of the disk of the primary and selective mass accretion on the secondaries. The formation of secondaries within the disk of primaries in close binaries has been proposed by many others before; it unifies the scenarios for formation of close binaries with that of substellar companions that also form within the primary disk, though on a different timescale. We also find that the observed trends with primary mass may be explained by a more prolonged phase of accretion episodes on the disk and by a more effective inward migration. Finally, in the Appendices we describe the detection of twelve new stellar companions from the BEAST survey and of a new BD companion at 9.599 arcsec from HIP 74752 using Gaia data, and we discuss the cases of possible BD and low-mass stellar companions to HIP 59173, HIP 62058, and HIP 64053.

High Precision Mass Balancing Method for the Fourth Harmonic of Mass Defect of Fused Quartz Hemispherical Resonator Based on Ion Beam Etching Process

In this paper, a novel ultra-high precision mass balancing method for fused quartz hemispherical resonator based on the ion beam etching process is proposed from the perspective of vibration mechanics. Firstly, the motion equations of resonator with mass defect are established to reveal the quantitative relationship between the amplitude of defective mass and frequency split, and the geometrical relationship between the distribution of defective mass and eigenfrequency axis, which is the equivalent morphology of mass defect. Secondly, according to the motion equations, the radial vibration model of resonator lip edge is deduced, then a new identification model for the vibration parameters composed of the frequency split, mechanical time constant, and azimuth of eigenfrequency axis based on the vibration envelope and spectral analysis is established. The vibration parameters are identified by nonlinear optimization method. After that, the mass removal function and etching efficiency function of ion beam acting on the resonator are calibrated by experimental data, then the etching trajectory is planned and the etching time is calculated. Finally, the experimental result of mass balancing indicates that the frequency split is reduced from 0.2354Hz to 0.0006Hz, and the quality factor is greater than 2.2×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> , which can significantly improve the vibration performance of resonator.

Eccentric compression performance of round-ended CFST slender columns with different aspect ratios

The objective of this study is to investigate the behaviour of round-ended concrete filled steel tubular (RECFST) under eccentric compression via tests and numerical analyses. This type of structural member has been utilized in arches and piers due to its advantages of major-minor axis distribution and low fluid resistance. Eleven specimens of RECFST slender columns were tested. The experimental results indicated that the failure mode of the RECFSTs was characterized by global buckling deformation. Finite element (FE) models were then established and benchmarked against the experimental data. Subsequently, the parametric investigations were performed to assess the influences of eccentricity ratio e (0.0–1.0), aspect ratio B/D (1.5–3.0), slenderness ratio λ (17–43), steel ratio α (8%–16%) and strengths of concrete fy (30 MPa–50 MPa) and steel fcu (355 MPa–420 MPa) on the carrying capacity of the RECFST slender columns. Considering distinct major and minor axes of the rectangular CFSTs, the applicability of design methods for rectangular CFSTs to RECFST slender columns was assessed by using the equivalent method. As the B/D increases, design methods tend to yield more conservative results under eccentric loading conditions. Generally, EC4 has demonstrated accurate predictions of the ultimate load for RECFSTs with B/D ranging from 1.5 to 3.0 after being equivalent to a rectangular section.

The Boundary Areas Structure of the Malko-Petropavlovsk Fracture Zone from Local Seismic Tomography and Earthquake Foci Mechanisms Data

Abstract —This study continues analysis of the new seismic tomographic structure of the suprasubduction complex of the central zone of Kamchatka, obtained from the dense local networks data of 2018–2020, and is devoted to the analysis of the velocity structure in the Malko-Petropavlovsk fracture zone margins and around them. The seismic tomographic model involves about 98,000 P- and S-wave travel times from 2963 local earthquakes from August 2018 to July 2020. The resolution of this model makes it possible to trace the feeding systems of volcanoes of the South Kamchatka and East Volcanic Belt to the slab surface, as well as to identify subvertical structural faults. To construct the orientations of the compression and extension axes we used the foci mechanisms of 41 earthquakes with М ≥ 4.5 from the catalog of the International Seismological Center for the period 1979–2019. Along the Malko-Petropavlovsk fracture zone, the Avacha transform fault is clearly traced in the geometry and mutual arrangement of velocity anomalies almost throughout the entire depth of the model. Comparison of seismic anomalies with a map of the directions of the compression and extension axes distribution from the earthquake foci mechanisms showed the correlation between the change in the value of the velocity anomalies along the Avacha transform fault with the axes direction change by almost 180°. A near-surface low-velocity anomaly to the depths of 25–35 km was found along the western border of the Malko-Petropavlovsk zone under the southern tip of the Sredinny Ridge. This anomaly probably marks the axes junction zone boundary of the ancient volcanic front along the Sredinny Ridge and the modern active Eastern Volcanic Belt, which formed as a result of the Kronotsky paleoarc accretion. To the west from the Sredinny Ridge southern tip, another low-velocity anomaly was revealed. This anomaly was traced to a depth of ~150 km, has a contrasting southern boundary confirmed by the distribution of the compression and extension axes directions by the earthquake foci mechanisms and apparently marks the southern boundary of the West Kamchatka block.

Can the orbital distribution of Neptune’s 3:2 mean-motion resonance result from stability sculpting?

ABSTRACT We explore a simplified model of the outcome of an early outer Solar System gravitational upheaval during which objects were captured into Neptune’s 3:2 mean-motion resonance via scattering rather than smooth planetary migration. We use N-body simulations containing the sun, the four giant planets, and test particles in the 3:2 resonance to determine whether long-term stability sculpting over 4.5 Gyr can reproduce the observed 3:2 resonant population from an initially randomly scattered 3:2 population. After passing our simulated 3:2 resonant objects through a survey simulator, we find that the semimajor axis (a) and eccentricity (e) distributions are consistent with the observational data (assuming an absolute magnitude distribution constrained by prior studies), suggesting that these could be a result of stability sculpting. However, the inclination (i) distribution cannot be produced by stability sculpting and thus must result from a distinct process that excited the inclinations. Our simulations modestly under-predict the number of objects with high-libration amplitudes (Aϕ), possibly because we do not model transient sticking. Finally, our model under-populates the Kozai subresonance compared to both observations and to smooth migration models. Future work is needed to determine whether smooth migration occurring as Neptune’s eccentricity damped to its current value can resolve this discrepancy.

Modelling uncertainties in wide binary constraints on primordial black holes

ABSTRACT Dark matter in the form of compact objects with mass Mco ≳ 10 M⊙ can be constrained by its dynamical effects on wide binary stars. Motivated by the recent interest in primordial black hole dark matter, we revisit the theoretical modelling involved in these constraints. We improve on previous studies in several ways. Specifically, we (i) implement a physically motivated model for the initial wide-binary semimajor axis distribution, (ii) include unbound binaries, and (iii) take into account the uncertainty in the relationship between semimajor axis and observed angular separation. These effects all tend to increase the predicted number of wide binaries (for a given compact object population). Therefore, the constraints on the halo fraction in compact objects, fco, are significantly weakened. For the wide binary sample used in the most recent calculation of the constraints, we find the fraction of halo dark matter in compact objects is fco &amp;lt; 1 for $M_{\rm co} \approx 300 \, \mathrm{ M}_{\odot }$, tightening with increasing Mco to fco &amp;lt; 0.26 for $M_{\rm co} \gtrsim 1000 \, \mathrm{ M}_{\odot }$.

Short-Term Impact of Different Corneal Incision Positions on Postoperative Astigmatism and Visual Quality After SMILE Surgery.

This study aimed to evaluate the short-term impact of different incision positions on astigmatism and visual quality after small incision lenticule extraction (SMILE) surgery. This prospective study enrolled patients who decided to have SMILE to correct myopia. Patients were randomly allocated into three groups of different incision positions (groupA, B, and C with incision position at 90°, 120°, and 150° respectively). Preoperative and postoperative visual acuity, spherical equivalent, and high-order aberrations (HOAs) were measured and compared among groups. Astigmatism was analyzed with the ASSORT Group Analysis Calculator based on the Alpins method. A total of 148 eyes were included for analysis (48 eyes in groupA, 50 eyes in groupB, and 50 eyes in groupC). At 1month postoperatively, the mean uncorrected distance visual acuity (UDVA) logMAR in groupA, B, and C was - 0.03, - 0.03, and - 0.04, respectively. The mean corrected distance visual acuity (CDVA) logMAR in groupA, B, and C was - 0.03, - 0.04, and - 0.04, respectively (P > 0.05). The mean postoperative spherical equivalent (SE) values were - 0.01 ± 0.38, - 0.07 ± 0.39, and - 0.16 ± 0.49 (D) in groupA, B, and C, respectively (P > 0.05). There was no statistically significant difference in preoperative and postoperative magnitude of astigmatism among different groups (P > 0.05). Significant differences were found in the distribution of astigmatism axis among the three groups at 1day (P = 0.02) and 1week (P = 0.02) postoperatively. However, such differences were no longer significant at 1month after surgery (P > 0.05). No significant differences were found in HOAs among different groups 1month after surgery (P > 0.05). Different incision positions have no effect on postoperative astigmatism and visual quality 1month after SMILE surgery, though differences were found in the distribution of the astigmatism axis within 1week after the surgery.