Dispersion and asymmetry of chiral gravitational waves in gyroscopic mechanical systems. Part 2: Continuum asymptotic models in equatorial and polar regions

Heliospheric Latitude Variations of Properties of Cometary Plasma Tails: A Test of the Ulysses Comet Watch Paradigm

Recent work has underscored the importance of membrane trafficking events during cytokinesis. For example, targeted membrane secretion occurs at the cleavage furrow in animal cells, and proteins that regulate endocytosis also influence the process of cytokinesis. Nonetheless, the prevailing dogma is that endosomal membrane trafficking ceases during mitosis and resumes after cell division is complete. In this study, we have characterized endocytic membrane trafficking events that occur during mammalian cell cytokinesis. We have found that, although endocytosis ceases during the early stages of mitosis, it resumes during late mitosis in a temporally and spatially regulated pattern as cells progress from anaphase to cytokinesis. Using fixed and live cell imaging, we have found that, during cleavage furrow ingression, vesicles are internalized from the polar region and subsequently trafficked to the midbody area during later stages of cytokinesis. In addition, we have demonstrated that cytokinesis is inhibited when clathrin-mediated endocytosis is blocked using a series of dominant negative mutants. In contrast to previous thought, we conclude that endocytosis resumes during the later stages of mitosis, before cytokinesis is completed. Furthermore, based on our findings, we propose that the proper regulation of endosomal membrane traffic is necessary for the successful completion of cytokinesis.

The composition and vertical structure of the lower cloud deck on Venus

In this study, the morphological properties of pollen of 14 species from 9 different sections of the genus Astragalus L. (Fabaceae) distributed in Türkiye were examined, identified, and compared under light microscope (LM) and scanning electron microscope (SEM). Pollen grains of the studied taxa are radially symmetrical and isopolar. Pollen shapes were determined as prolate, subprolate, spheroidal, and prolate-spheroidal. The polar axis lengths of the pollen grains were determined to be between 24.5 and 34.4 μm, and the equatorial axis lengths were determined to be between 22.4 and 27.5 μm. The aperture type of pollen grains is mainly trizonacolporate, rarely trisyncolporate. Colpus are thin and long with acute ends. The shapes of the pores were determined as oblate, suboblate, or oblate-spheroidal. Colpus lengths were found to be between 18.2 and 28.8 μm, and widths were found to be between 2.7 and 7.1 μm. In the studied species, four types of ornamentation were determined according to the differences in the polar region and equatorial region. Type 1: perforate in polar and equatorial regions; Type 2: perforate in polar region, microreticulate in equatorial region; Type 3: microreticulate in polar and equatorial regions; Type 4: psilate-perforate in polar region, microreticulate in equatorial region. Principal component analysis (PCA) and unweighted pair group method using arithmetic average (UPGMA) analyses showed that morphological characters of pollen grains were effective in distinguishing species but could not contribute significantly to a distinction according to sections. Pollen size, colpus characteristics, and ornamentation were determined to be important characteristics that distinguish the studied taxa. This study contributes to Astragalus taxonomy and different sub-branches of palynology.

We analyze the extraction of the rotational energy of a Kerr black hole (BH) endowed with a test charge and surrounded by an external test magnetic field and ionized low-density matter. For a magnetic field parallel to the BH spin, electrons move outward(inward) and protons inward(outward) in a region around the BH poles(equator). For zero charge, the polar region comprises spherical polar angles -60∘≲θ≲60∘ and the equatorial region 60∘≲θ≲120∘. The polar region shrinks for positive charge, and the equatorial region enlarges. For an isotropic particle density, we argue the BH could experience a cyclic behavior: starting from a zero charge, it accretes more polar protons than equatorial electrons, gaining net positive charge, energy and angular momentum. Then, the shrinking(enlarging) of the polar(equatorial) region makes it accrete more equatorial electrons than polar protons, gaining net negative charge, energy, and angular momentum. In this phase, the BH rotational energy is extracted. The extraction process continues until the new enlargement of the polar region reverses the situation, and the cycle repeats. We show that this electrodynamical process produces a relatively limited increase of the BH irreducible mass compared to gravitational mechanisms like the Penrose process, hence being a more efficient and promising mechanism for extracting the BH rotational energy.

Comet de Vico (122P) and latitude variations of plasma phenomena

High-resolution 3-μm spectra of Jupiter: Latitudinal spectral variations influenced by molecules, clouds, and haze

Kyushu University, Kyushu Institute of Technology and Fukuoka Institute of Technology are now designing, developing and building a micro-satellite called “QSAT”. The primary objective of QSAT is understanding the mechanism of spacecraft charging, which can be achieved with the onboard magnetometer, high-frequency probe (HP) and Langmuir probe (LP). The magnetometer measures the magnetic field variations caused by field-aligned currents (FACs) in the polar and equatorial regions. Polar FACs are well understood, while equatorial FACs are not. The science goals are as follows: (1) to better understand FACs in the polar region, (2) to compare the FACs observed in orbit with ground-based MAGDAS observations, (3) to investigate spatial distribution of FACs in the equatorial region. FACs play a crucial role in the coupling between solar wind, magnetosphere and ionosphere in terms of energy transfer. Also if we understand the relationship between the space and ground-based FACs data, then we can conduct long-term study on the solar wind–magnetosphere–ionosphere coupling in the future by mainly using data from ground-based magnetometer arrays.

Formation of cholinergic synapse-like specializations at developing murine muscle spindles

The surface of Ganymede is dominated by crystalline water ice, but amorphous water ice has been observed at the poles of both hemispheres [1]. Recent hyperspectral data from the James Webb Space Telescope have confirmed the presence of amorphous water ice in the north polar region of the leading hemisphere [2]. Because Ganymede is embedded in the Jovian magnetosphere, its surface is continuously irradiated by charged particles (ions and electrons), which induces radiolysis, chemistry, sputtering of surface molecules, and likely amorphization of water ice [3,4]. However, the irradiation flux is not uniform across Ganymede's surface due to its own magnetic field [5], and the equatorial region is partially shielded from ion and electron irradiation. This fact, along with higher temperatures at lower latitudes that efficiently promotes recrystallization, may explain that the presence of amorphous water ice is restricted to the polar regions.Here, we question the presence of amorphous water ice in the north polar region using a numerical approach. The ion and electron fluxes impinging on the polar and equatorial regions are taken from a number of previous publications [6,7]. We first estimate the erosion rate of water ice at the surface for different case models using sputtering yields of H2O and O2 [8,9,10]. The nuclear and electronic doses deposited in the subsurface with depth were calculated using the stopping powers generated by the SRIM software (http: //www.srim.org/) [11]. The contribution of bremsstrahlung emission from decelerating electrons was not included in this calculation. The erosion rate mitigates the actual doses accumulated in the surface, and our numerical code included a moving surface front.Our calculations show that water ice erosion is dominated by O and S ions, and the contribution of electrons is 3 orders of magnitude smaller. Although sputtering is more efficient at high temperatures [12], we found that the polar regions are more eroded due to a higher ion flux. The doses accumulated in the surface reach a steady state within ~ 100000 years and are in the range of 100-1000 eV/atom. These values are underestimates, corresponding to a maximum erosion rate where no sputtered water molecules sink back to the surface. The fraction of crystalline water ice transformed into amorphous water ice was estimated using the kinetics reported in [13]. Since amorphous water ice crystallization competes with radiolytic amorphization, we also considered this process and used the kinetic parametric equation of [14]. Finally, our calculations show that amorphous water ice is essentially formed in the polar regions, where temperatures are < 100 K, to a depth of ~600 µm. This result is consistent with the detection of amorphous water ice at the north pole of Ganymede by the JWST telescope, but not with the lack of detection at the south pole. Our analysis of experimental data in the literature shows that the kinetics of water ice amorphization is not well constrained in the temperature range 90-120 K for low energy projectiles. This issue is being addressed through irradiation experiments. Ongoing simulations also include more realistic erosion rates. [1] Ligier et al. (2019), Icarus 333, 496–515.[2] Bockelée-Morvan et al. (2024), Astronomy and Astrophysics 681, A27[3] Cooper et al. (2001), Icarus 149, 133-159[4] Johnson et al. (2004), Jupiter. The Planet, Satellites and Magnetosphere, 485-512[5] Kivelson et al. (1996), Nature 384, 537-541[6] Poppe et a. (2018), Journal of Geophysical Research 123, 389-391[7] Liuzzo et al. (2020), Journal of Geophysical Research 125, e28347[8] Fama et al. (2008), Surface Science 602, 156-161[9] Johnson et al. (2009), Europa, 507[10] Teolis et al. (2017), Journal of Geophysical Research 122, 1996-2012[11] Ziegler et al. (2010), Nuclear Instruments and Methods in Physics Research B 268, 1818-1823[12] Brown et al. (1980), Physical Review Letters 45, 1632-1635[13] Fama et al. (2010), Icarus 207, 314-319[14] Schmitt et al. (1989), Physics and Mecanics of Cometary Materials 302, 65-69

Chandrayaan-I, is India's first scientific mission to the moon. It is launched with prime objective to expand scientific knowledge about the origin and evolution of moon. Chandrayaan-I mission carried various remote sensing instruments into space for achieving its scientific objectives. Mini-SAR was launched on Chandrayaan-I mission and operated for nine months. The prime goal of Mini-SAR on Chandrayaan-I mission is to map permanently dark areas near Polar Regions. Mini SAR data is already analyzed by the researchers in past for identifying water ice deposits. However studies comparing the behavior of lunar craters present near Polar Regions and equatorial Regions is scarce if non-existent. In present work authors have taken initiative for comparing the behavior of lunar craters present near polar and equatorial regions. Various child parameters extracted from strokes parameters for comparison purpose.

Evaluation of the IRI model using CHAMP observations in polar and equatorial regions

We investigate a model for the excitation of high-order oscillations in roAp stars. In this model we assume that the strong concentration of magnetic field about the magnetic poles is enough to suppress convection. Thus the model considered is composed of two polar regions, in which convection is presumed to be suppressed totally, and an equatorial region, where the convection is unaffected. This model is generated by building pairs of locally spherically symmetrical equilibria to represent the polar and equatorial regions of the star, which are patched together below the base of the convection zone. Gravitational settling of heavy elements is taken into account by choosing appropriate chemical composition profiles for both the polar and equatorial regions. Our results indicate that the composite model is unstable against axisymmetric non-radial high-order modes of pulsation that are aligned with the magnetic poles. The oscillations are excited by the κ mechanism acting principally in the hydrogen ionization zones of the polar regions. The effect of the lateral inhomogeneity on the second frequency differences is also investigated; we find that the perturbation to them by the inhomogeneity is of the same order as the second differences themselves, thereby hindering potential attempts to use such differences to identify the degrees of the modes in a straightforward way.

The role of the nerve in maintaining the ultrastructural integrity of avian muscle spindles was investigated by denervating the pigeon's extensor digitorum communis for periods of 10, 19, and 28 days. The equatorial region of control intrafusal fibers had a reduced density of myofilaments. Sensory endings contained mitochondria and structures resembling synaptic vesicles, and were associated with satellite cells. In the polar region, fibers had a high concentration of myofilaments; small motor endings, unlike sensory endings, lay outside of the fiber's basal lamina. The outer capsule consisted of thin, tightly layered cells which gradually became reduced in number distal to the equatorial region. In both equatorial and polar regions the capsule became more disrupted with longer denervation periods, and lysosomes and phagocytes became more abundant. The equatorial region of denervated fibers contained many myofibrils and some had peripherally-located nuclei, unlike the controls; sensory terminals were absent. The polar region of some fibers had disorganized myofilaments and others had a reduced myofilament density. Fiber diameters increased significantly in both regions. Thus, denervated intrafusal fibers lost some characteristics which distinguish them from extrafusal fibers.

4-μm Polar Continuum of Jupiter