Local Arm Research Articles

Impact of adjuvant sorafenib treatment after local ablation for HCC in the phase II SORAMIC trial

The aim of the study was to evaluate the efficacy and safety of adjuvant sorafenib treatment compared with placebo in patients with hepatocellular carcinoma who underwent local ablation. The SORAMIC trial is a randomised controlled trial with diagnostic, local ablation, and palliative sub-study arms. After initial imaging within the diagnostic study, patients were assigned to local ablation or palliative arms. In the local ablation cohort, patients were randomised 1:1 to local ablation+ sorafenib vs. local ablation+ placebo. The primary endpoint was time-to-recurrence (TTR). Secondary endpoints were local control rate and safety in terms of adverse events and quality-of-life. The recruitment was terminated prematurely after 104 patients owing to slow recruitment. One patient was excluded because of a technical failure. Fifty-four patients were randomised to local ablation+ sorafenib and 49 to local ablation+ placebo. Eighty-eight patients who underwent standardised follow-up imaging comprised the per-protocol population. The median TTR was 15.2 months in the sorafenib arm and 16.4 months in the placebo arm (hazard ratio 1.1; 95% CI 0.53-2.2; p= 0.82). Out of 136 lesions ablated within the trial, there was no difference in local recurrence rate between sorafenib (6/69, 8.6%) and placebo groups (5/67, 5.9%; p= 0.792).Overall (92.5% vs. 71.4%, p= 0.008) and drug-related (81.4% vs. 55.1%, p= 0.003) adverse events were more common in the sorafenib arm compared with the placebo arm. Dose reduction because of adverse events were common in the sorafenib arm (79.6% vs. 30.6%, p <0.001). Adjuvant sorafenib did not improve in TTR or local control rate after local ablation in patients with hepatocellular carcinoma within the limitations of an early terminated trial. Local ablation is the standard of care treatment in patients with early stages of hepatocellular carcinoma, along with surgical therapies. However, there is a risk of disease recurrence during follow-up. Sorafenib, an oral medication, is a routinely used treatment for patients with advanced hepatocellular carcinoma. This study found that sorafenib treatment after local ablation in people with early hepatocellular carcinoma did not significantly improve the disease-free period compared with placebo. EudraCT 2009-012576-27, NCT01126645.

Spiral-like features in the disc revealed by Gaia DR3 radial actions

Context. The so-called action variables are specific functions of the positions and velocities that remain constant along the stellar orbit. The astrometry provided by Gaia Early Data Release 3 (EDR3), combined with the velocities inferred from the Radial Velocity Spectrograph (RVS) spectra of Gaia DR3, allows for the estimation of these actions for the largest volume of stars to date. Aims. We explore such actions with the aim of locating structures in the Galactic disc. Methods. We computed the actions and the orbital parameters of the Gaia DR3 stars, assuming an axisymmetric model for the Milky Way. Using Gaia DR3 photometric data, we also selected a subset of giant stars with better astrometry as a control sample. Results. We find that the maps of the percentiles of the radial action JR reveal arc-like segments. We found a high JR region centered at R ≈ 10.5 kpc of 1 kpc width, as well as three arc-shape regions dominated by circular orbits at inner radii. We also identified the spiral arms in the overdensities of the giant population. Conclusions. For Galactic coordinates (X, Y, Z), we find good agreement with the literature in the innermost region for the Scutum-Sagittarius spiral arms. At larger radii, the low JR structure tracks the Local arm at negative X, while for the Perseus arm, the agreement is restricted to the X &lt; 2 kpc region, with a displacement with respect to the literature at more negative longitudes. We detected a high JR area at a Galactocentric radii of ∼10.5 kpc, consistent with some estimations of the Outer Lindblad Resonance location. We conclude that the pattern in the dynamics of the old stars is consistent in several places with the spatial distribution of the spiral arms traced by young populations, with small potential contributions from the moving groups.

On the Origin of the North Celestial Pole Loop

The North Celestial Pole Loop (NCPL) provides a unique laboratory for studying the early-stage precursors of star formation. Uncovering its origin is key to understanding the dynamical mechanisms that control the evolution of its contents. In this study, we explore the 3D geometry and the dynamics of the NCPL using high-resolution dust extinction data and H i data, respectively. We find that material toward Polaris and Ursa Major is distributed along a plane similarly oriented to the Radcliffe wave. The Spider projected in between appears disconnected in 3D, a discontinuity in the loop shape. We find that the elongated cavity that forms the inner part of the NCPL is a protrusion of the Local Bubble (LB) likely filled with warm (possibly hot) gas that passes through and goes beyond the location of the dense clouds. An idealized model of the cavity as a prolate spheroid oriented toward the observer, reminiscent of the cylindrical model proposed by Meyerdierks et al., encompasses the protrusion and fits into arcs of warm H i gas expanding laterally to it. As first argued by Meyerdierks et al., the nonspherical geometry of the cavity and the lack of OB stars interior to it disfavor an origin caused by a single point-like source of energy or multiple supernovae. Rather, the formation of the protrusion could be related to the propagation of warm gas from the LB into a pre-existing nonuniform medium in the lower halo, the topology of which was likely shaped by past star formation activity along the Local Arm.

Արհեստական բանականության տեխնոլոգիայով սպառազինությունների արտադրության արդյունավետության հարցեր / Issues of effective Artificial Intelligence-implemented arms production

The artificial intelligence (IA)-implemented armament has globally grown into a key factor providing for strategic balance of powers. Every state pushes for positioning itself as a full-fledged participant in global technological race, in pursuit of economic, and military, and geopolitical advantages in the sphere of AI development. In such conditions, small states (especially those dealing with serious security problems) cannot stand aside, and also strive to replenish their military and military-political arsenal with “smart” weapons or accumulate the necessary potential for their own development and production of AI technologies. However, in terms of small states, the problem becomes noticeably more intricate, since they encounter the need to choose not only between imports and production, but also decide on the area of greater focus on the AI development – civilian or military. The research herein was conducted with the aim of contemplating on the effectiveness of the AI-implemented “smart” weapons production and determining the feasibility for such small states with major security problems like Armenia, investing funds in the development of the local military industry with a focus on the arms imports. One of the important issues is predicting the time to reach such a level of local arms production at which it will be possible to ensure the security of one’s own country. To this end, the author has studied academic approaches to the reallocation of military spending on the production of “smart” weapons, and identified the advantages of AI-based weapons in solving defense and security problems. The findings of the study allow us to conclude that from the perspective of solving defense-security tasks the peculiarities of the geo-economic environment in Armenia require that all the resources be directed towards the development of AI technologies with a focus on their application in the military sphere. That is the only direction the development of which will make room for saving military spending and the most efficient use of the limited budget, as well as modernize the armed forces to the earliest possible time.

Signatures of anisotropic diffusion around PeVatrons in 100 TeV gamma-ray data

The Tibet AS$\gamma$ collaboration has reported a diffuse $\gamma$-ray emission signal from the Galactic Plane. We consider the possibility that the diffuse emission from the outer Galactic Plane at the highest energies is produced by cosmic rays spreading from a single supernova-type source either in the Local or Perseus arm of the Milky Way. We show that anisotropic diffusion of multi-PeV cosmic rays along the Galactic magnetic field can produce an extended source spanning ten(s) of degrees on the sky, with a flux-per-unit-solid-angle consistent with Tibet AS$\gamma$ measurements. Observations of this new type of very extended sources, and measurements of their morphologies, can be used to characterize the anisotropic diffusion of PeV cosmic rays in the Galactic magnetic field, and to constrain the locations and properties of past PeVatrons.

Impact of handgrip exercise and ischemic preconditioning on local and remote protection against endothelial reperfusion injury in young men.

Ischemic preconditioning (IPC), cyclical bouts of nonlethal ischemia, provides immediate protection against ischemic injury, which is evident both locally and remotely. Given the similarities in protective effects of exercise with ischemic preconditioning, we examined whether handgrip exercise also offers protection against endothelial ischemia-reperfusion (IR) injury and whether this protection is equally present in the local (exercised) and remote (contralateral, nonexercised) arm. Fifteen healthy males (age, 24 ± 3 yr; body mass index, 25 ± 2 kg/m2) attended the laboratory on three occasions. Bilateral brachial artery flow-mediated dilation (FMD) was examined at rest and after a temporary IR injury in the upper arm. Before the IR injury, in the dominant (local) arm, participants performed (randomized, counterbalanced): 1) 4 × 5 min unilateral handgrip exercise (50% maximal voluntary contraction), 2) 4 × 5 min unilateral IPC (220 mmHg), or 3) 4 × 5 min rest (control). Data were analyzed using repeated-measures general linear models. Allometrically scaled FMD declined after IR in the control condition (4.6 ± 1.3% to 2.2 ± 1.7%, P < 0.001), as well as following handgrip exercise (4.6 ± 1.6% to 3.4 ± 1.9%, P = 0.01), however, was significantly attenuated with IPC (4.5 ± 1.4% to 3.8 ± 3.5%, P = 0.14). There were no differences between the local and remote arm. Our findings reinforce the established protective effects of IPC in young, healthy males and also highlight a novel strategy to protect against IR injury with handgrip exercise, which warrants further study.

An asymmetric morbilliform eruption in an adult male

An asymmetric morbilliform eruption in an adult male

IMPLEMENTING A HEALTHY BRAIN INITIATIVE IN THE NATION’S LARGEST COUNTY JURISDICTION

Abstract In 2019, there were an estimated 166,857 Los Angeles County (LAC) residents living with Alzheimer’s disease. By 2040, this number is expected to rise by 150% to 405,382, with 152,980 and 35,341 of them, respectively, being Black and Latinx. Locally, there is special interest in reducing dementia risk among the two communities, as modifiable risk factors such as untreated hypertension, diabetes, and smoking are disproportionately higher in these groups (e.g., hypertension – Black, 35.9% vs. White, 27.3%; diabetes – Black and Latinx, 14.4% and 13.6%, respectively, vs. White, 8.8%). In LAC, considerable investments have been made to help create and implement the local arm of the California Healthy Brain Initiative (Healthy Brain Initiative: Los Angeles or HBI-LA). Launched in 2019, HBI-LA utilized a multi-level, multi-sector approach to expand the breadth and quality of tools available to the Black and Latinx communities and key stakeholders who work with these communities. The initiative set out to complete the following State-approved objectives: (i) educate the public and health professionals about dementia care and prevention; (ii) develop policies that improve access to health, aging, and prevention services for those with cognitive decline; and (iii) disseminate reliable, culturally sensitive information and tools to promote best practices on brain health. The present investigation examines the stepwise process that LAC took to achieve these objectives, including the development of two culturally tailored educational workshops (one for community members, one for healthcare and social services professionals) and how a U.S. Congressperson and County Supervisor supported dissemination efforts.

The Cassiopeia Filament: A Blown Spur of the Local Arm

We present wide-field and high-sensitivity CO(1–0) molecular line observations toward the Cassiopeia region, using the 13.7 m millimeter telescope of the Purple Mountain Observatory. The CO observations reveal a large-scale highly filamentary molecular cloud within the Galactic region of 132.°0 ≥ l ≥ 122.°0 and −1.°0 ≤ b ≤ 3.°0 and the velocity range from approximately +1 to +4 km s−1. The measured length of the large-scale filament, referred to as the Cassiopeia Filament, is ∼390 pc. The observed properties of the Cassiopeia Filament, such as length, column density, and velocity gradient, are consistent with those synthetic large-scale filaments in the inter-arm regions. Based on its observed properties and location on the Galactic plane, we suggest that the Cassiopeia Filament is a spur of the Local arm, which is formed due to the galactic shear. The western end of the Cassiopeia Filament shows a giant arc-like molecular gas shell, which extends in the velocity range from roughly −1 to +7 km s−1. Finger-like structures, with systematic velocity gradients, are detected in the shell. The CO kinematics suggest that the large shell is expanding at a velocity of ∼6.5 km s−1. Both the shell and finger-like structures outline a giant bubble with a radius of ∼16 pc, which is likely produced by the stellar wind from the progenitor star of a supernova remnant. The observed spectral line widths suggest that the whole Cassiopeia Filament was quiescent initially until its west part was blown by the stellar wind and became supersonically turbulent.

Mapping Milky Way disk perturbations in stellar number density and vertical velocity using Gaia DR3

We have mapped the number density and mean vertical velocity of the Milky Way’s stellar disk out to roughly two kiloparsecs from the Sun using Gaia Data Release 3 (DR3) and complementary photo-astrometric distance information from StarHorse. For the number counts, we carefully masked spatial regions that are compromised by open clusters, great distances, or dust extinction and used Gaussian processes to arrive at a smooth, non-parametric estimate for the underlying number density field. We find that the number density and velocity fields depart significantly from an axisymmetric and mirror-symmetric model. These departures, which include projections of the Gaia phase-space spiral, signal the presence of local disturbances in the disk. We identify two features that are present in both stellar number density and mean vertical velocity. One of these features appears to be associated with the Local Spiral Arm. It is most prominent at small heights and is largely symmetric across the mid-plane of the disk. The density and velocity field perturbations are phase-shifted by roughly a quarter wavelength, suggesting a breathing mode that is propagating in the direction of Galactic longitude l ∼ 270 deg. The second feature is a gradient in the stellar number density and mean vertical velocity with respect to galactocentric radius. This feature, which extends across the entire region of our analysis, may be associated with the extension of the Galactic warp into the solar neighbourhood in combination with more localised bending waves.

Peering into the Milky Way by FAST: IV. Identification of two new Galactic supernova remnants G203.1+6.6 and G206.7+5.9

A 5$^{\circ}$ $\times$ 7$^{\circ}$ sky area containing two large radio structures of G203.1+6.6 and G206.7+5.9 with a size of about 2.5$^{\circ}$ and 3.5$^{\circ}$ respectively is scanned by using the L-band 19-beam receiver of the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The FAST L-band receiver covers a frequency range of 1.0-1.5 GHz. Commissioning of the receiving system, including the measurements of the half-power beam width, gain, and main-beam efficiency is made by observing the calibrators. The multi-channel spectroscopy backend mounted to the receiver allows an in-band spectral-index determination. The brightness-temperature spectral indices of both objects are measured to be $\beta$ $\sim$ $-$2.6 to $-$2.7. Polarized emission is detected from the archival Effelsberg $\lambda$11 cm data for all the shell structures of G203.1+6.6 and G206.7+5.9. These results clearly indicate a non-thermal synchrotron emitting nature, confirming that G203.1+6.6 and G206.7+5.9 are large shell-type supernova remnants (SNRs). Based on morphological correlation between the radio continuum emission of G206.7+5.9 and the HI structures, the kinematic distance to this new SNR is estimated to be about 440 pc, placing it in the Local Arm.

Molecular and Atomic Clouds Associated with the Gamma-Ray Supernova Remnant Puppis A

We have carried out a study of the interstellar medium (ISM) toward the shell-like supernova remnant (SNR) Puppis A using NANTEN CO and ATCA H i data. We synthesized a comprehensive picture of the SNR radiation by combining the ISM data with the gamma-ray and X-ray distributions. The ISM, both atomic and molecular gas, is dense and highly clumpy, and is distributed all around the SNR, but mainly in the northeast. The CO distribution revealed an enhanced line intensity ratio of CO(J = 2–1)/(J = 1–0) transitions as well as CO line broadening, which indicate shock heating/acceleration. The results support the assertion that Puppis A is located at 1.4 kpc, in the Local Arm. The ISM interacting with the SNR has a large mass of ∼104 M ⊙, which is dominated by H i, showing good spatial correspondence with the Fermi-LAT gamma-ray image. This favors a hadronic origin of the gamma-rays, while an additional contribution from a leptonic component is not excluded. The distribution of the X-ray ionization timescales within the shell suggests that the shock front ionized various parts of the ISM at epochs ranging over a few to ten thousand years. We therefore suggest that the age of the SNR is around 104 yr as given by the largest ionization timescale. We estimate the total cosmic-ray energy W p to be 1047 erg, which is well placed in the cosmic-ray escaping phase of an age–W p plot including more than ten SNRs.

Role of the renin-angiotensin system in the development of COVID-19-associated neurological manifestations.

SARS-CoV-2 causes COVID-19, which has claimed millions of lives. This virus can infect various cells and tissues, including the brain, for which numerous neurological symptoms have been reported, ranging from mild and non-life-threatening (e.g., headaches, anosmia, dysgeusia, and disorientation) to severe and life-threatening symptoms (e.g., meningitis, ischemic stroke, and cerebral thrombosis). The cellular receptor for SARS-CoV-2 is angiotensin-converting enzyme 2 (ACE2), an enzyme that belongs to the renin-angiotensin system (RAS). RAS is an endocrine system that has been classically associated with regulating blood pressure and fluid and electrolyte balance; however, it is also involved in promoting inflammation, proliferation, fibrogenesis, and lipogenesis. Two pathways constitute the RAS with counter-balancing effects, which is the key to its regulation. The first axis (classical) is composed of angiotensin-converting enzyme (ACE), angiotensin (Ang) II, and angiotensin type 1 receptor (AT1R) as the main effector, which -when activated- increases the production of aldosterone and antidiuretic hormone, sympathetic nervous system tone, blood pressure, vasoconstriction, fibrosis, inflammation, and reactive oxygen species (ROS) production. Both systemic and local classical RAS’ within the brain are associated with cognitive impairment, cell death, and inflammation. The second axis (non-classical or alternative) includes ACE2, which converts Ang II to Ang-(1–7), a peptide molecule that activates Mas receptor (MasR) in charge of opposing Ang II/AT1R actions. Thus, the alternative RAS axis enhances cognition, synaptic remodeling, cell survival, cell signal transmission, and antioxidant/anti-inflammatory mechanisms in the brain. In a physiological state, both RAS axes remain balanced. However, some factors can dysregulate systemic and local RAS arms. The binding of SARS-CoV-2 to ACE2 causes the internalization and degradation of this enzyme, reducing its activity, and disrupting the balance of systemic and local RAS, which partially explain the appearance of some of the neurological symptoms associated with COVID-19. Therefore, this review aims to analyze the role of RAS in the development of the neurological effects due to SARS-CoV-2 infection. Moreover, we will discuss the RAS-molecular targets that could be used for therapeutic purposes to treat the short and long-term neurological COVID-19-related sequelae.

Numerical investigation on the effect of axial magnetic field on metallurgical quality of ingots during vacuum arc remelting process

The electromagnetic stirring force generated by the axial magnetic field (AMF) interacting with the process current greatly affects the solidification process and consequently the metallurgical quality of ingots, but there are few studies about the effect of AMF on the multi-physics field involving solute transport during VAR process. Based on this, a three-dimensional full-size transient model has been developed to investigate the role of AMF on the metallurgical quality evaluated by the segregation defect and solidification quality in this paper. All essential considerations of the fluid flow, heat transfer and solute transport are incorporated in the model. Both the local solidification time (LST) and secondary dendrite arm spacing (SDAS) are adopted as indexes to characterize the solidification quality. The results show that the stirring force caused by the AMF greatly promotes the downward heat transfer and thus leads to deeper molten pool. The final value of volume-averaged segregation extent is greatly reduced by 24.13% as the AMF intensity increases from 0 to 50 G, while the difference of this value between 50 G and 100 G is only 1.96%. The volume-averaged values of the LST and SDAS are all reduced with the increase of AMF intensity, in which both values change from 1088 s to 190 μm without AMF to 890 s and 182 μm under 100 G. These results indicate that the application of AMF can significantly improve the metallurgical quality of ingots, but this effect becomes more and more limited with the increase of AMF intensity.

The Radcliffe wave as the gas spine of the Orion arm

The Radcliffe wave is a ∼3 kpc long coherent gas structure containing most of the star-forming complexes near the Sun. In this Letter we aim to find a Galactic context for the Radcliffe wave by looking into a possible relationship between the gas structure and the Orion (local) arm. We use catalogs of massive stars and young open clusters based on Gaia Early Data Release 3 (EDR3) astrometry, in conjunction with kiloparsec-scale 3D dust maps, to investigate the Galactic XY spatial distributions of gas and young stars. We find a quasi-parallel offset between the luminous blue stars and the Radcliffe wave, in that massive stars and clusters are found essentially inside and downstream from the Radcliffe wave. We examine this offset in the context of color gradients observed in the spiral arms of external galaxies, where the interplay between density wave theory, spiral shocks, and triggered star formation has been used to interpret this particular arrangement of gas and dust as well as OB stars, and outline other potential explanations as well. We hypothesize that the Radcliffe wave constitutes the gas reservoir of the Orion (local) arm, and that it presents itself as a prime laboratory to study the interface between Galactic structure, the formation of molecular clouds in the Milky Way, and star formation.

Parameters of the Radcliffe Wave from Masers, Radio Stars, and T Tauri Stars

The presence of the Radcliffe wave is shown both in the positions and in the vertical velocities of masers and radio stars belonging to the Local Arm. This gives the impression that the structure of the Radcliffe wave is not a wave in the full sense of the word. It is more like a local high-amplitude burst, rapidly fading away. Moreover, this structure has the largest amplitude in the immediate vicinity of the Sun, where the main ``contributors'' are the Gould Belt stars. Based on the spectral analysis of masers, the following estimates of the geometric and kinematic characteristics of the wave were obtained: the largest value of the vertical coordinate $z_{max}=87\pm4$ pc and the wavelength $\lambda=2.8\pm0.1$ kpc, the vertical velocity perturbation amplitude reaches $W_{max}=5.1\pm0.7$ km s$^{-1}$ and the wavelength found from vertical velocities is $\lambda=3.9\pm1.6$ kpc. The Radcliffe wave also manifests itself in the positions of very young stars that have not reached the main sequence stage. We extracted a sample of such stars from the Gaia DR2$\times$AllWISE database and obtained the following estimates from them: $z_{max}=118\pm3$ pc and wavelength $\lambda=2.0\pm0.1$ kpc.

Optical Linear Polarization Study toward Czernik 3 Open Cluster at Different Spatial Scales

We present the optical linear polarization observation of stars toward the core of the Czernik 3 cluster in the Sloan i band. The data were obtained using the EMPOL instrument on the 1.2 m telescope at Mount Abu Observatory. We study the dust distribution toward this cluster by combining the results from our polarization observations with the data from Gaia EDR3, WISE, and the H i, 12CO surveys. In addition, we use the polarimetric data of previously studied clusters within 15° of Czernik 3 to understand the large-scale dust distribution. The observational results of Czernik 3 show a large range in the degree of polarization, indicating that the dust is not uniformly distributed over the plane of the sky, even on a small scale. The distance to Czernik 3 is constrained to 3.6 ± 0.8 kpc using the member stars in the core region identified from Gaia EDR3 astrometry. This makes it one of the most distant clusters observed for optical polarization so far. The variation of observed degree of polarization and extinction toward this cluster direction suggests the presence of at least two dust layers along this line of sight at distances of ∼1 and ∼3.4 kpc. There is an indication of the presence of dust in the center of the cluster as seen from an increase in the degree of polarization and WISE W4 flux. The large-scale distribution of dust reveals the presence of a region of low dust content between the Local Arm and the Perseus arm.

Chemo-kinematics of the Milky Way spiral arms and bar resonances: Connection to ridges and moving groups in the solar vicinity

Making use of a new high-resolution spiral galaxy simulation as well as Gaia DR2 and EDR3 data complemented by chemical abundances from the Galah DR3, APOGEE DR16, and LAMOST DR5 surveys, we explore the possible link between the Milky Way (MW) spiral arms, (R, vϕ) ridges, and moving groups in local vR-vϕ space. We show that the tightly wound main spiral arms in the N-body simulation can be successfully identified using overdensities in angular momentum (AM) or guiding space and also in the distribution of dynamically cold stars close to their guiding centres. Stars in the AM overdensities that travel over many kiloparsec in radius trace extended density ridges in (R, vϕ) space and overdensities in the vR-vϕ plane of a solar neighbourhood (SNd)-like region, similar to those observed in the Gaia data. Similarly, the AM space of the MW contains several overdensities that correlate with a wave-like radial velocity pattern; this pattern is also reproduced by stars well beyond the SNd. We find that the fraction of Gaia stars located near their guiding centres shows three large-scale structures that approximately coincide with the MW spiral arms traced by distributions of maser sources in the Sagittarius, Local, and Perseus arms. This approach does not work for the Scutum arm near the end of the bar. Similar to the simulation, the stars in the AM overdensities follow the main (R, vϕ) density ridges with nearly constant angular momentum. When these ridges cross the SNd, they can be matched with the main vR-vϕ features. Thus we suggest that the Hat is the inner tail of the Perseus arm, one of the Hercules components is the Sagittarius arm, and the Arcturus stream is likely to be the outermost tail of the Scutum-Centaurus arm. Based on previous work, the bar corotation is suggested to coincide with the second, vϕ ≈ −55 km s−1 Hercules stream ridge, and the OLR with the Sirius stream. The latter is supported by a sharp decrease in mean metallicity beyond the Sirius stream, which is an expected behaviour of the OLR, limiting migration of the metal-rich stars from the inner MW. In various phase-space coordinates, the AM overdensity stars have a mean metallicity that is systematically higher by about 0.05 dex than the metallicity of the surrounding stars. This is a predicted behaviour of the spiral arms. We show that the wave-like metallicity pattern can be traced at least up to |z|≈1 kpc. It is linked to radial velocity variations seen even farther (|z|≈2 kpc) from the Galactic mid-plane.

Parameters of the Galactic Spiral Density Wave from Masers with Parallax Errors Less Than 10$$\boldsymbol{\%}$$

We have studied the kinematics of Galactic masers and radio stars with measured VLBI trigonometric parallaxes and proper motions. We have considered masers with relative trigonometric parallax errors less than 10\% and determined the Galactic rotation parameters from them. In particular, the linear rotation velocity of the Galaxy at the solar distance $R_0$ has been found to be $244.4\pm4.3$ km s$^{-1}$ (for the adopted $R_0=8.1\pm0.1$ kpc). We have performed a joint and separate spectral analysis of the radial, residual tangential, and vertical maser velocities. For example, from the vertical maser velocities we have estimated the velocity perturbation amplitude $f_W=5.2\pm1.5$ km s$^{-1}$ with the wavelength $\lambda_W=2.6\pm0.7$ kpc, arguing for the influence of the spiral density wave on the vertical stellar velocities. Based on 104 masers within 3 kpc of the Sun, as a result of the joint solution, we have estimated the radial, $f_R=6.7\pm1.1$ km s$^{-1}$, and tangential, $f_\theta=2.6\pm1.2$ km s$^{-1}$, velocity perturbations, the perturbation wavelength $\lambda=2.1\pm0.3$ kpc, and the Sun's phase in the Galactic spiral density wave $\chi_\odot=-148\pm15^\circ$. We have confirmed the presence of the Radcliffe wave in the spatial distribution of masers and radio stars belonging to the Local Arm.

Pulsar Survey With the QiTai 110 m Radio Telescope

With a collecting area of 9400 m2, the Xinjiang QiTai 110 m radio Telescope (QTT) will allow for a significant advance in the search and observation of pulsars. We have updated the galactic electron density model, scattering model, spectral distribution, and radial distribution of PsrPopPy to generate the population of isolate radio pulsars in the Galaxy. The spiral arm, including the local spiral arm, is considered when generating pulsar locations. By simulation, we estimate the number of previously undetected radio pulsars that QTT will discover with its possible receivers for different strategies. Using the PAF receiver, 2200 previously unknown pulsars could be discovered in 43 days. The 96-beam PAF receiver can produce ∼10.56 GB of data per second.