bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial coherence filtering of normal incidence light through leaky mode engineering
Authors: Li Hang , Haerinia Mohammad , Zheng Bowen , An Sensong , Tang Hong , Dong Yunxi , Fowler Clayton , Guo Wei , Zhang Hualiang , Ghebrebrhan Michael
Published: March 2022

Filtering light by coherence by metasurfaces would enable compact, integrable coherence filters. A recent such proposal centered on a metasurface of zigzags. Here, we show that spatial coherence filtering can be achieved at normal incidence with a similar zigzag metasurface and can be traced to the band structure of the leaky modes of the thin film structure. We fabricate a metasurface of zigzags etched through a gold film deposited on a GaAs substrate and measure the transmittance of long wave infrared radiation. Selectivity matches predictions based on the band structure of fully coherent radiation. Furthermore, the degree of coherence filtering is shown to be controlled by the Q-factor of leaky modes.
Equivalence of conditions on initial data below the ground state to NLS with a repulsive inverse power potential
Authors: Hamano Masaru , Ikeda Masahiro
Published: March 2022

In this paper, we consider the nonlinear Schrödinger equation (NLS) with a repulsive inverse power potential. First, we show some global well-posedness results and “blow-up or grow-up” results below the ground state without the potential. Then, we prove equivalence of the conditions on the initial data below the ground state without potential. Recently, we established the existence of a radial ground state and characterized it by the virial functional for NLS with a general potential in two or higher space dimensions obtained by Hamano and Ikeda [“Characterization of the ground state to the intercritical NLS with a linear potential by the virial functional,” in Advances in Harmonic Analysis and Partial Differential Equations, Trends in Mathematics (Birkhäuser/Springer, Cham, 2020), pp. 279–307]. Then, we also prove a global well-posedness result and a “blow-up or grow-up” result below the radial ground state with a repulsive inverse power potential obtained by Hamano and Ikeda [“Characterization of the ground state to the intercritical NLS with a linear potential by the virial functional,” in Advances in Harmonic Analysis and Partial Differential Equations, Trends in Mathematics (Birkhäuser/Springer, Cham, 2020), pp. 279–307].
Analysis and experimental research on high frequency magnetic properties of different magnetostrictive materials under variable temperature conditions
Authors: Huang Wenmei , Xia Zhiyu , Guo Pingping , Weng Ling
Published: March 2022

Magnetostrictive materials have excellent magneto-mechanical properties and are widely used in the field of energy conversion. Temperature has an important influence on the magnetic properties of them. Accurately studying the temperature dependence of magnetostrictive materials is a necessary prerequisite for the design of precision actuators. In this paper, we constructed a high-frequency magnetic property measurement system that can control the temperature. The magnetic characteristics of Terfenol-D, Fe-Ga and Fe-Co were measured at temperatures ranging from 10 °C to 80 °C, the frequencies from 1 kHz to 20 kHz and magnetic induction amplitudes from 0.01 T to 0.07 T. The temperature dependence of the three materials under different exciting conditions was comprehensively compared. The variation trends and temperature sensitivities of the coercivity, permeability, equivalent inductance, equivalent resistance and the magnetic energy losses are analyzed respectively. The results of this paper are oriented to practical engineering applications and can be used for high-frequency loss prediction and temperature control system design.
The effect of high pressure on the electrical and transport properties of the InSb-MnSb magnetic eutectic composition
Authors: Kochura A. V. , Dzhamamedov R. G. , Mekhiya A. B. , Oveshnikov L. N. , Arslanov T. R. , Rodionov V. V. , Alam M. , Kuzmenko A. P. , Davydov A. B. , Aronzon B. A.
Published: March 2022

In this work we studied transport properties of eutectic InSb-MnSb crystals with oriented MnSb needle-like inclusions under a hydrostatic pressure up to P = 8 GPa and after its application. We show that the pressure-induced variation of the samples resistivity and transport parameters at room temperature can be interpreted in the terms of crystal phase transition of the InSb matrix. We argue that the irreversibility of this transition, deduced from transport measurements, may stem from the composite nature of the crystals studied. The resistivity of the samples subjected to high pressures increases upon cooling, which can be a consequence of the increased disorder accompanying the irreversible transition. Magnetotransport data for these samples suggest that charge carriers interact with a low-temperature magnetic phase. The latter can be formed by isolated Mn atoms in the InSb matrix.
Preparation of Fe-Pt thin-sheet magnets using exfoliation behavior
Authors: Nakano M. , Miyahara Y. , Tsuruoka A. , Yamashita A. , Yanai T. , Honda T. , Shinshi T. , Fukunaga H.
Published: March 2022

In this research, Fe-Pt thin sheets thicker than 10 microns with Fe contents ranging from 50 to 60 at. % were prepared. Isotropic Fe-Pt thin sheets could be obtained by taking advantage of the exfoliation behavior after depositing Fe-Pt films on Si substrates using a laser ablation technique. A post-annealing process was used to obtain the L10 phase, and the (BH)max value of Fe-Pt thin sheets showed approximately 70 kJ/m3. Moreover, the test of a cantilever containing the obtained Fe-Pt thin sheet showed good mechanical characteristics.
A fungal effector suppresses the nuclear export of AGO1–miRNA complex to promote infection in plants
Authors: Zhu Chen , Liu Jia-Hui , Zhao Jian-Hua , Liu Ting , Chen Yun-Ya , Wang Chun-Han , Zhang Zhong-Hui , Guo Hui-Shan , Duan Cheng-Guo
Published: March 2022

Significance

Increasing evidence demonstrates that small RNAs can serve as trafficking effectors to mediate bidirectional transkingdom RNA interference (RNAi) in interacting organisms, including plant–pathogenic fungi systems. Previous findings demonstrated that plants can send microRNAs (miRNAs) to fungal pathogen
Verticillium dahliae
to trigger antifungal RNAi. Here we report that
V. dahliae
is able to secret an effector to the plant nucleus to interfere with the nuclear export of AGO1–miRNA complexes, leading to an inhibition in antifungal RNAi and increased virulence in plants. Thus, we reveal an antagonistic mechanism that can be exploited by fungal pathogens to counteract antifungal RNAi immunity via manipulation of plant small RNA function.
FMRP promotes transcription-coupled homologous recombination via facilitating TET1-mediated m5C RNA modification demethylation
Authors: Yang Haibo , Wang Yumin , Xiang Yufei , Yadav Tribhuwan , Ouyang Jian , Phoon Laiyee , Zhu Xueping , Shi Yi , Zou Lee , Lan Li
Published: March 2022

Significance

This study shows that Fragile X mental retardation protein (FMRP) promotes messenger RNA (mRNA)-dependent recombination via facilitating ten-eleven translocation protein 1 (TET1)-mediated mRNA methyl-5-cytosine (m5C) demethylation. Loss of FMRP leads to damage induced mRNA m5C and R-loop accumulation at sites of active transcription, defective recombination repair, and increased radiosensitivity of tumor cells. FMRP-dependent RNA m5C demethylation and R-loop resolving during DNA repair are important for repair completion and the maintenance of genome stability. The removal of m5C by the FMRP–TET1 axis is coupled with R-loop dissolution, which ensures proper completion of DNA repair and survival of cells after DNA damage. These findings significantly advance our understanding of the regulation of RNA modifications in R-loop dynamics during DNA repair.
Single-molecule fluorescence imaging and deep learning reveal highly heterogeneous aggregation of amyloid-β 42
Authors: Meng Fanjie , Yoo Janghyun , Chung Hoi Sung
Published: March 2022

Significance

There are various diseases caused by protein aggregation such as Alzheimer’s, Parkinson’s, and Huntington’s diseases. From the diversity in the fibril structure, aggregation is expected to occur via heterogeneous pathways. However, characterization of this heterogeneity is extremely difficult because it requires following individual fibril formation in a mixture from early oligomerization stages. In this work, we investigated aggregation of the 42-residue isoform of amyloid β (Aβ42) using single-molecule fluorescence imaging and deep learning. We could track the growth of individual fibrils, which allows for a quantitative description of heterogeneous fibril formation and discovery of a new fibril nucleation mechanism. Further characterization of heterogeneity involving Aβ42 will be important for better understanding the disease mechanism.
Syntheses of three-dimensional catenanes under kinetic control
Authors: Wu Yong , Guo Qing-Hui , Qiu Yunyan , Weber Jacob A. , Young Ryan M. , Bancroft Laura , Jiao Yang , Chen Hongliang , Song Bo , Liu Wenqi , Feng Yuanning , Zhao Xingang , Li Xuesong , Zhang Long , Chen Xiao-Yang , Li Hao , Wasielewski Michael R. , Stoddart J. Fraser
Published: March 2022

Significance

During the past decades, the development of efficient methodologies for the creation of mechanically interlocked molecules (MIMs), such as catenanes and rotaxanes, has not only laid the foundation for the design and syntheses of artificial molecular machines (AMMs) but also opened up new research opportunities in multiple disciplines, ranging from contemporary chemistry to materials science. In this study, we describe a suitane-based strategy for the construction of three-dimensional (3D) catenanes, a subset of MIMs that are far from easy to make. Together with synthetic methodologies based on the metal coordination and dynamic covalent chemistry, this approach brings us one step closer to realizing routine syntheses of 3D catenanes.
Global genomic instability caused by reduced expression of DNA polymerase ε in yeast
Authors: Zhang Ke , Sui Yang , Li Wu-Long , Chen Gen , Wu Xue-Chang , Kokoska Robert J. , Petes Thomas D. , Zheng Dao-Qiong
Published: March 2022

Significance

Although most studies of the genetic regulation of genome stability involve an analysis of mutations within the coding sequences of genes required for DNA replication or DNA repair, recent studies in yeast show that reduced levels of wild-type enzymes can also produce a mutator phenotype. By whole-genome sequencing and other methods, we find that reduced levels of the wild-type DNA polymerase ε in yeast greatly increase the rates of mitotic recombination, aneuploidy, and single-base mutations. The observed pattern of genome instability is different from those observed in yeast strains with reduced levels of the other replicative DNA polymerases, Pol α and Pol δ. These observations are relevant to our understanding of cancer and other diseases associated with genetic instability.
Nitrogen addition frequency and propagule pressure influence
Solidago canadensis
invasion into native plant community
Authors: Liu Xuan-Shao , Cai Jing-Fang , Liu Lin , Sun Kai , Jiang Fan , Shen Yi-Luan , A Si-Ha , Li Hong-Li
Published: March 2022

Introduction

Propagule pressure (i.e., the number of propagules) has long been recognized to play an essential role in plant invasion. But it is not clear whether propagule pressure influences the invasion of exotic plants into native plant communities when different frequencies of nitrogen are added.

Method

We established an experiment with three plant communities that included native plant communities alone (four grasses, two legumes and two forbs) or native plant communities with one or five invasive plants,
Solidago canadensis
, under three frequencies of nitrogen addition (no addition or low or high addition with the same amount).

Results

High propagule pressure significantly enhanced the biomass and relative dominance index of
S. canadensis
. Moreover, high propagule pressure only decreased the total and aboveground biomass of the legumes. However, the competitive effect between
S. canadensis
and the native community and biomass of the whole native community varied according to different frequencies.

Conclusion

Overall, high propagule pressure encouraged invasion by
S. canadensis
, while alow nitrogen frequency was advantageous for the native community to resist invasion in this experiment. The results provide a scientific basis to manage and control the invasion of
S. canadensis
.
Prion-like domains drive CIZ1 assembly formation at the inactive X chromosome
Authors: Sofi Sajad , Williamson Louisa , Turvey Gabrielle L. , Scoynes Charlotte , Hirst Claire , Godwin Jonathan , Brockdorff Neil , Ainscough Justin , Coverley Dawn
Published: March 2022

CIZ1 forms large assemblies at the inactive X chromosome (Xi) in female fibroblasts in an Xist lncRNA-dependent manner and is required for accurate maintenance of polycomb targets genome-wide. Here we address requirements for assembly formation and show that CIZ1 undergoes two direct interactions with Xist, via independent N- and C-terminal domains. Interaction with Xist, assembly at Xi, and complexity of self-assemblies formed in vitro are modulated by two alternatively spliced glutamine-rich prion-like domains (PLD1 and 2). PLD2 is dispensable for accumulation at existing CIZ1–Xi assemblies in wild-type cells but is required in CIZ1-null cells where targeting, assembly, and enrichment for H3K27me3 and H2AK119ub occur de novo. In contrast, PLD1 is required for both de novo assembly and accumulation at preexisting assemblies and, in vitro, drives formation of a stable fibrillar network. Together they impart affinity for RNA and a complex relationship with repeat E of Xist. These data show that alternative splicing of two PLDs modulates CIZ1’s ability to build large RNA–protein assemblies.
Investigation of the high-field transport, Joule-heating-driven conductivity improvement and low-field resistivity behaviour in lightly-reduced free-standing graphene oxide papers
Authors: Thamkrongart Krongtham , Ramamoorthy Harihara , Buapan Kanokwan , Chiawchan Tinna , Somphonsane Ratchanok
Published: March 2022

Free-standing reduced graphene oxide (rGO) has been gaining popularity for its use in supercapacitors and battery applications due its facile synthesis, multi-layered structure, and high-current carrying capacity. Pertinent to the successful implementation of such applications, however, is the need to develop a thorough understanding of the electrical properties of such materials when subject to high applied electric fields. In this work, we undertake a detailed study of high-field electrical properties of mm-scale, lightly-reduced, rGO papers. Our results reveal that theI–Vcurves exhibit substantial nonlinearity with associated hysteresis that depends strongly on the applied electric field. The nonlinear behaviour which was interpreted using conventional transport models of Fowler–Nordheim tunnelling and space charge limited conduction revealed that while these models provided good qualitative fits to our data, they were quantitatively lacking, thus leaving the issue of high-field transport mechanisms in rGO open for debate. CarefulI–Vcycling experiments with measurement time-delay introduced between cycles revealed that the observed hysteresis contained recoverable and non-recoverable parts that we identified as arising from charge trapping and Joule heating effects, respectively. Time-dependent measurements showed that these effects were characterized by two distinct time scales. Importantly, the Joule heating was found to cause a permanent conductivity improvement in the rGO via the ‘current annealing’ effect by effectively eliminating oxygenated groups from the rGO. The analysis of the electrical breakdown in our samples resembled a thermal runaway-like event that resulted in premature damage to the rGO. Finally, we investigated the low-field resistivity in the 80 K–300 K temperature range. The reduced activation energy analysis revealed a robust power law behaviour below 230 K, while deviating from this trend at higher temperatures. For samples that received current annealing treatment, a reduced value for the power law exponent was obtained, confirming the effective lowering of disordered regions.
Enhanced perpendicular magnetic anisotropy of ferrimagnetic Mn4N films deposited on the glass substrate
Authors: Li Wenchang , Xu Xinxing , Gao Tenghua , Harumoto Takashi , Nakamura Yoshio , Shi Ji
Published: March 2022

Mn4N films have been prepared on the glass substrate by reactive magnetron sputtering, using Mn3N2 as the seed layer. Compared with Mn4N film directly grown on the glass substrate, the crystallinity and perpendicular magnetic anisotropy (PMA) of the Mn4N film with the seed layer are significantly enhanced. By varying the thickness of the Mn3N2 seed layer, the structural and magnetic properties are systematically investigated. It is shown that the seed layer thickness is pivotal in the growth of Mn4N with good crystallinity. The crystallinity of Mn4N first improves with the increase in the layer thickness of Mn3N2, and degrades after an optimal thickness; this is related to the change in the surface roughness of the Mn3N2 layers. The Mn3N2 layer not only promotes the growth of Mn4N film with c-axis orientation, but also provides additional N atoms to the growing surface to prevent Mn4N from being oxidized. This simple method can be used to prepare high-quality Mn4N films on a glass substrate, which show strong PMA and are suitable for spintronics applications.
Prediction and comparative analysis of CTCF binding sites based on a first principle approach
Authors: Oiwa Nestor Norio , Li Kunhe , Cordeiro Claudette E , Heermann Dieter W
Published: March 2022

We calculated the patterns for the CCCTC transcription factor (CTCF) binding sites across many genomes on a first principle approach. The validation of the first principle method was done on the human as well as on the mouse genome. The predicted human CTCF binding sites are consistent with the consensus sequence, ChIP-seq data for the K562 cell, nucleosome positions for IMR90 cell as well as the CTCF binding sites in the mouse HOXA gene. The analysis of Homo sapiens, Mus musculus, Sus scrofa, Capra hircus and Drosophila melanogaster whole genomes shows: binding sites are organized in cluster-like groups, where two consecutive sites obey a power-law with coefficient ranging from 0.3292 ± 0.0068 to 0.5409 ± 0.0064; the distance between these groups varies from 18.08 ± 0.52 kbp to 42.1 ± 2.0 kbp. The genome of Aedes aegypti does not show a power law, but 19.9% of binding sites are 144 ± 4 and 287 ± 5 bp distant of each other. We run negative tests, confirming the under-representation of CTCF binding sites in Caenorhabditis elegans, Plasmodium falciparum and Arabidopsis thaliana complete genomes.
The evolution of the solitons in periodic photonic moiré lattices controlled by rotation angle with saturable self-focusing nonlinearity media
Authors: Zhang Yingying , Qin Yali , Zheng Huan , Ren Hongliang
Published: March 2022

We explored the evolution and stability of solitons formed by a Gaussian beam excited on-site in periodic photonic moiré lattices controlled by an angle with saturable self-focusing nonlinearity medium of lower applied bias, which makes use of the square lattices as a reference. When we introduce the rotation angle

θ

(

θ
∈
(
0
,

π

/

2

)

), which satisfies the Pythagorean theorem and is commensurable, it will create a new lattice structure by rotating and superimposing two square lattices of the same period, which we called periodic photonic moiré lattices. Its energy band structure is special, which includes the flat band, and even opens the higher band-gap compared with square lattices. On the other hand, when we reduce the applied bias of the crystal, periodic photonic moiré lattices can still suppress the diffraction behaviour of Gaussian beam effectively and realize light localization by contrast with square lattices. Moreover, we proved the stability of the solitons formed by the Gaussian beams excited on-site in periodic photonic moiré lattices and revealed that the solitons could keep stable, but their stability regimes depend on the rotation angle shrinks and belong to the different bandgap. The discovery of the photonic moiré lattice provides a fresh approach for suppressing the diffraction behaviour of light and reduces the requirement for nonlinearity, which is beneficial for the diversity of our crystal material selection, and also provides a new way to manufacture high-efficiency optoelectronic devices.
Conservative mass transfer on eclipsing binary AE Phe from O-C diagram analysis
Authors: Vidante C , Malasan H L
Published: March 2022

Eclipsing binary is an edge-on binary system where the components appear to be eclipsing one another. Eclipsing binaries therefore give a lot of information on the systems’ behavior, one of them from their period change. O-C diagram exhibits the deviation of the observed time of minimum from the calculated ones and its analysis will reveal the responsible mechanism, such as a hidden third component, apsidal motion, and mass transfer. AE Phe (V = 8.15 mag and spectral class G0V) is a W UMa W-type binary. Previous studies of its degree of contact have revealed AE Phe to be a shallow-contact binary. Photometric data were taken using PROMPT (Panchromatic Robotic Optical Monitoring and Polarimetry Telescopes), CTIO on October 4th, 2013 on four filters: B, V, R, and I. The Kwee and van Woerden (1956) method was also used to determine AE Phe’s time of minimum. Analysis of the O-C diagram (taken from 1975 toward our observation) suggest that the period of AE Phe shows a long-term continuous increase. These period increase and degree of contact suggest that AE Phe is undergoing thermal relaxation oscillation (TRO) and is evolving to a broken-contact phase, with a possibility of angular momentum loss (AML) through magnetic braking.
Morpho-kinematics study of planetary nebula Sh 2-71 based on astrophysical 3-d modeling
Authors: Fajrin M. , Malasan H. L. , Akbar E. I.
Published: March 2022

A planetary nebula is formed when a low to intermediate mass star approaches the end of its life. Before the ejected materials finally interact with and dissipate into the interstellar matters, the nebula will be visible surrounding its former stellar core. The variety of planetary nebulae visual appearances indicates that the material ejected and leave the central star behind in unique ways. Morpho-kinematics study aims to find out the 3-d shape using the help of imaging and spectroscopic observations. Imaging allows on to observe the projection of planetary nebulae onto the plane perpendicular to the line of sight to the observer, while spectroscopy gives the ability to infer the expansion characteristics from the spectrum produced by shells within planetary nebulae. We report the 3-d shape modeling of Sh 2-71 (PNG 035.9-01.1, α(J2000.0) = 19h01m59.96s, δ(J2000.0) = 02°09’16.1”) using images obtained from Gemini Multi-Object Spectrograph (GMOS), Hong Kong/Australian Astronomical Observatory/Strasbourg Observatory Ha Planetary Nebula (HASH PN Database), and DSS image combined with high-resolution long-slit spectra from San Pedro Martir Kinematic Catalogue of Planetary Nebulae. The 3-d modeling is carried out with software that specializes in modeling three dimensional astrophysical object SHAPE. The acquired data from observations show that Sh 2-71 possesses a torus with three bipolar lobes while modeling by SHAPE tells that the torus is inclined by 37° and the bipolar lobes are on the same plane.
Anisotropic quark star and the energy conditions
Authors: Claudia T.S. Gracella , Sulaksono Anto
Published: March 2022

One of the compact objects that are attractive for investigating their energy conditions is quark stars. The existence of radial and tangential pressure differences in quark stars can cause anisotropic effects on the stars. We focus on and examine the energy conditions of quark stars using the Einstein Field Equation Solution. The energy stability of an anisotropic quark star can be determined by evaluating the profile of the pressure and energy density of the star using the anisotropic EOS as an input. The used equation is the extended MIT Bag Model, which involves the constant B and interaction parameter a
4 and the corresponding parameters of anisotropic part. It is known that parameter a
4 affects the mass distribution of quark stars to be more anisotropic. This anisotropic pressure also affects the energy condition profile of the star. We find the energy state of an anisotropic quark star satisfies the energy state of an ideal fluid.
Membership and age determination of M67 open cluster using GAIA EDR3 data
Authors: Ghosh Esan Mouli , Sulistiyowati  , Tucio Princess , Fajrin Muhammad
Published: March 2022

We present our study on the membership and age determination of M67 (NGC 2682), one of the oldest open clusters known to date. Proper motions and parallax of stars collected in the Gaia Early Data Release 3 are used to derive the cluster members by employing the Hierarchical Density-Based Spatial Clustering of Applications with Noise algorithm, which is further improved upon using a Gaussian Mixture Model. We calculate the position of the cluster centre and the parallax to be α = 08h51m24s±1m33s, δ = 11°49’12"±0°22’48" and 1.1497±0.06 mas respectively. The proper motion of the cluster is obtained to be μa
= −10.96 ± 0.20 mas/yr and μs
= −2.90 ± 0.19 mas/yr. Subsequently, we perform an isochrone fitting to the Color-Magnitude Diagram (CMD) of M67 source members by using the Automated Stellar Cluster Analysis tool (ASteCA). Our findings estimate the log age, metallicity (z), reddening (EB–V
), and distance modulus (m – M)0 to be 9.630 ± 0.033 log-years, 0.01865 ± 0.001, 0.037 ± 0.008, and 9.409 ± 0.031 respectively.
Recurring Nova RS Oph spectroscopic observation at Bosscha Observatory and ITERA Astronomical Observatory (IAO)
Authors: Imaduddin I. , Fajrin M. , Muztaba R. , Hafizah I. , Akbar E. I. , Malasan H. L.
Published: March 2022

We report low and intermediate resolution spectra of the recurrent nova RS Oph taken at two observatories. A low resolution spectrum (R ≈ 1000) was taken at ITERA Astronomical Observatory (IAO) in Lampung by using 25 cm (f/8) RC Astrograph telescope equipped with a LISA Pack Spectrograph eight days after the outburst. Twenty intermediate spectra (R ≈ 5000) were taken on several consecutive nights using LHIRES III spectrograph attached to a 25 cm (f/10) Meade LX-200R telescope at Bosscha Observatory, Lembang. We identified significant change in the strength of atomic lines from low resolution spectrum compared to previous observations. A clear and distinct Balmer emission decrement can be seen from the spectrum. Our intermediate resolution spectroscopy revealed a variability of P-Cygni profile on a broad Hα line. The P-Cygni profile evolved and disappeared at recent observations. It is thought that there was a new shell formed after the outburst and later combined with the previous shell in the next days. From the broad Hα profile, we measured and found decreasement in expansion velocity during our observation. We estimated vexp
= 2907.97 ± 64.14 km/s and vexp
= 997.12 ± 8.18 km/s on 1.6440 and 22.729 days after the outburst, respectively.
Report on seeing, sky brightness, and meteorological properties measurements at Timau National Observatory site
Authors: Saputra M B , Danarianto M D , Murti M D , Alwan M A , Yanti R J , Chikmah
Published: March 2022

With the existence of the Timau National Observatory, the site testing of the observatory location must be carried out to provide supporting data regarding the quality of the National Observatory site. Some site testing that needs to be done are seeing, sky brightness, and meteorological properties measurements. In this paper, the seeing and sky brightness measurements in July-August 2021 are presented. These measurements were conducted using the Differential Image Motion Monitor (DIMM) method with a 20 cm telescope and a Sky Quality Meter (SQM) respectively. From the results of these measurements, it was found that the site of Timau National Observatory has good seeing conditions with median of 0.92 arcseconds and most sky brightness values are around 22.02 magnitude per square arcsecond. The monitoring results of meteorological properties, such as air temperature, barometric pressure, relative humidity, and wind speed and direction during August 2021 that recorded by an automatic weather station are also presented.
Artificial intelligence generated solar farside magnetogram using conditional generative adversarial network
Authors: Dani T , Muhamad J , Nurzaman M Z , Kesumaningrum R , Sulistiani S , Pangestu A D
Published: March 2022

A solar flare occurs due to a magnetic field reconnection above the active region. The active region magnetic complexity observed in the magnetogram could be used as proxies for solar flare forecasting. It is also known that solar flares that occur from emerging active regions located near the solar disk eastern limb can still have an impact on the Earth. Therefore, magnetic observation of active regions in the solar farside is important to forecast east limb flares occurrences. This study utilizes the conditional Generative Adversarial Network (cGAN) model to generate Artificial Intelligence (AI) solar farside magnetogram. Our model was trained using the solar frontside observations dataset from Solar Dynamic Observatory (SDO)/Atmospheric Imaging Assembly (AIA) 304 Angstrom as input images and SDO/Helioseismic and Magnetic Imager (HMI) magnetogram as output images. Our model generates solar farside magnetogram using solar farside observation from Solar Terrestrial Relations Observatory (STEREO)/Extreme Ultraviolet Imager (EUVI) 304 Angstrom. We also conducted validation on the similarity of our AI-generated magnetogram with the magnetogram observation from SDO/HMI using the Structural Similarity Index (SSIM) method. SSIM obtained an average similarity value of 0.61±0.06 for training data and 0.47±0.02 for validation data which contain active regions producing flares.
Potential hazards analysis of the space debris over 10 cm in size based on their orbital parameters
Authors: Neflia  , Ahmad N , Rohmah F
Published: March 2022

The increasing population of artificial space objects every year triggers a polemic about the safety of launching satellites into orbit as well as the safety of satellites operating in space. The artificial space object also provides a potential danger when it re-entry and then falls to Earth. Indonesia as a country that has the 2nd longest coastline in the world and has a span of 1/8 of the world’s circumference (± 5000 km) is very vulnerable to experience atmospheric re-entry of which these space objects might fall to the Earth. Space objects that have the potential to experience re-entry and then fall to the Earth originate from space objects with a size of more than 10 cm. Until 2020, there are 6560 space objects with size 0.1<RCS<1 m2 and 9526 space objects with size RCS>1 m2. There are 5678 pieces of space debris with 4435 pieces with size 0.1<RCS<1m2 and 1236 pieces over 1m2. Of all space debris, only those with an altitude below 200 km potentially fall to the Earth which is around 1517 pieces. In addition, the most dangerous debris over the Indonesia region commonly has a low inclination with the passage around 12 to 16 times a day. However, there are only 15 objects which satisfy this category with a small number. Hence, the need of space debris surveillance should be done for mitigation purposes.
Prototype of automatic satellite streak detection, identification and initial orbit determination pipeline from optical observation
Authors: Danarianto M. D. , Maharani A. M. , Falah B. M. , Rohmah F.
Published: March 2022

We present a working prototype of automatic satellite streak detection, identification and initial orbit determination pipeline from optical telescope images based on python. The pipeline process calibrated and plate-solved astronomical images in fits format. We utilized Hough transform-based feature detection to detect the light streaks and extract the equatorial position based on the image header information. The streaks were then identified by comparing their center position with the calculated SGP4 based satellite position from available TLE data. The corresponding initial orbit is calculated by utilizing the Laplacian method by interpolating the streak position and time. We test the pipeline by using 85 blind-survey 10 cm telescope images around the celestial equator. The pipeline correctly detects 123 lines with 0.85 sensitivity, automatically identify 92 detected satellites unambiguously and determine the initial orbit of 118 streaks.
The development of PIL extraction application in active region of SDO/HMI magnetogram
Authors: Utama A Z , Nurzaman M Z , Dani T
Published: March 2022

The Polarity Inversion Line (PIL) on the active region (AR) is a parameter that correlates with the occurrence of the solar flare. This research has developed application to extract the PIL length in the AR. Image processing techniques were used to detect and classify AR from the SDO/HMI Magnetogram image of 1024x1024 pixels. The detection of AR in magnetogram images has its challenges because the ARs are constructed by the white (black) regions represent the magnetic positive (negative) polarities. To improve detection accuracy, the application used The Solar Region Summary (SRS), compiled by SWPC, and the centroid position of sunspot on SDO/HMI Continuum as additional information. The results of AR detection had high accuracy because SRS stores the centroid position of the flaring active region at peak time with the Stonyhurst heliographic on the solar disk which is converted to Cartesian coordinates. The application test used 1450 images and obtained the PIL length on the peak time of the X-class and M-class flares from 2011-2017. The application detected the high distribution of PIL length in the range of 120 to 580 Mm for X class flare, and 120 to 390 Mm for M-class flare. This research provides new data that has the potential to improve the machine learning-based solar flare prediction models.
Africa mid and low latitude ionosphere response observed during the geomagnetic storms of July 15 and 9 March 2012 using GPS
Authors: Anoruo Chukwuma Moses , Okeke Francisca Nneka , Okpala Kingsley Chukwudi
Published: March 2022

In this paper, the initial and recovery phases of July 15 and March 9, 2012 geomagnetic storms in African mid and low latitudes ionosphere has been studied using GPS. We employ relative total electron content (rTEC) variations using 2 stations from the Africa Geodetic Reference Frame (AFREF) to characterize African sector ionosphere responses during both storms. To characterize rTEC, we employ 15-day median-average sliding-window during the storm. Both storms lasted 18 h with Dst minima -139 nT for July 15 and -145 nT for March 9, when solar plasma wind speed recorded 545 km/s and 712 km/s respectively. The recovery phase lasted 48 h for -139 nT storm and 46 h for -145 nT when solar plasma wind speed recorded 485 km/s and 428 km/s respectively. It may be attributed that storm recovery phases do not depend on storm severity but the response of ionosphere during storms. Results show Positive storm dominates during the recovery phase and interplanetary electric field and solar plasma wind speed contribute to storm enhanced density. Ionospheric disturbances observed due to prompt penetration electric field shaped the magnetic field and prompted pre-storm rTEC enhancement. Plasma convection at mid-latitudes of African sector observed rTEC enhancements which did not appear in other studied sector results. Further observations should be carried out using other storms.
A model of the deviation between IRI-2016 and ionospheric TEC observation based on GISTM at low latitude Indonesia region
Authors: Husin A. , Suraina  , Putra AY. , Rasidi H.
Published: March 2022

The diurnal variation pattern of total electron content(TEC) from the International Recurrence Ionosphere (IRI-2016) model is generally is good agreement with observational data at all latitudes. However, at low latitudes the IRI TEC is not as accurate as in midlatitudes. Some reports showed that the IRI-2016 TEC model at the maximum and minimum solar activities at low latitudes tends to be underestimate. In this paper, TEC from GISTM (GPS Ionospheric Scintillation and TEC Monitoring) that is installed at Pontianak station (0.03° S;109.33°E geomagnetic latitude 9.7°S ) used for validation and evaluation of IRI-2016 TEC model over the low latitude Indonesian sector. Data from the 2012 - 2014 period representing solar maximum and data from 2018 representing solar minimum, were used in this study. We also developed VTEC deviation (ΔTEC) model by using multiple linear regression and tested the model by using data 2019. Results show that IRI-2016 generally reproduces the diurnal variations pattern but underestimates the observation data for many hours each day especially during maximum solar activity 2012-20114. The highest deviation in the equinoctial months and lowest during the June and December solstice. The deviation (ΔTEC) model showed good agreement with observation data on January and December but not for other months especially on equinox months. Testing of the VTEC deviation model using 2019 data did not show significant improvement compared to the IRI-2016 itself, which generally produces good TEC prediction in most of the months except for equinox months.
The feasibility study of Barus city as the new astrotourism destination from astronomical and meteorological aspect
Authors: Butar-Butar Arwin Juli Rakhmadi , Putra Singgih Prana , Hidayat Muhammad , Putraga Hariyadi
Published: March 2022

Astrotourism is a tourist activity that shows attractions in the form of astronomical phenomena and outer space. Astrotourism activities that can be carried out by tourists are such as studying and exploring astronomical phenomena such as eclipses, meteor showers, and so on in the conditions of the night sky. An important condition for the advancement of astrotourism in an area is that the area has dark skies that are characterized by no severe light pollution and had adequate atmospheric conditions such as at least clouds covering the sky so that celestial objects can be observed properly, temperature, humidity, wind speed. and good rainfall so that visitors or tourists can comfortably be at astronomical tourist sites for a long time. We’ve done collecting atmospheric data using portable weather station and sky brightness data using Unihedron Sky Quality Meter LU-DL type device from July 10th - 11th 2021 and we collected data from windy.com for atmospheric particle content and cloud coverage during those dates. The results showed that Barus can become a new potential astrotourism destination specifically in Northern Sumatera or broadly in Indonesia where the Light pollution in Barus city is quite low, with a maximum value of brightness sky of 21.6, 20.8, and 21.8 MPSAS for the east, zenith, and west directions, respectively; Atmospheric conditions are quite good with an average temperature of 25.9 °C, the humidity of 89.2%, wind speed of 2.07 km/h, rainfall of 33.1 mm, amount of particles in the atmosphere 0.13 AOD and heat index of 27.2 °C Future study is needed from other aspects to make Barus become a new astrotourism destination in Indonesia.
Study of Cassegrain-type antenna for radio telescope
Authors: Sobirin Farhan Fatwa , Nugraha Satia , Haz Fauzia , Sitompul Peberlin
Published: March 2022

There are many critical parameters in the design of a radio telescope, such as antenna gain and antenna resolution. In telecommunications, radar, and radio telescopes, an antenna is a very important component. There are many designs of the antenna, such as dipole array and parabolic antenna. Parabolic antennas also have many sub-reflector and antenna methods that control the radio wave, such as the Cassegrain type. A Cassegrain-type antenna is a parabolic antenna in which the feed antenna is mounted at or behind the surface of the main parabolic reflector dish. For the transmitter system, the beam of radio waves from the feed antenna illuminates the secondary reflector (sub-reflector), which reflects it back to the main reflector dish and then forward to space. The Cassegrain design is widely used in parabolic antennas, for large antennas in satellite ground stations, communication satellites, and radio telescopes. In this paper discusses the design of a Cassegrain-type antenna for radio telescope, basic calculation, diameter size of the main reflector of 20 meters, the diameter size of sub-reflector of 2.5 meters, and frequency of 22 GHz and 43 GHz.
Floating microplastic loads in the nearshore revealed through citizen science
Authors: de Haan William P , Uviedo Oriol , Ballesteros Maria , Canales Íngrid , Curto Xavier , Guart Montse , Higueras Sara , Molina Alex , Sanchez-Vidal Anna
Published: March 2022

Research on plastic pollution has rapidly expanded in recent years and has led to the discovery of vast amounts of microplastics floating on the surface of subtropical oceanic gyres. However, the distribution of floating plastic in the ocean is still poorly constrained, and there is a lack of information from a few meters from the coastline where the largest plastic emissions take place. Here, we provide a comprehensive study on the loads of plastic debris in the coastal surface waters of the NW Mediterranean Sea using data from 124 manta trawl deployments collected along 7 months by citizen scientists. Our results reveal that pollution by microplastics in the nearshore is likely subject to seasonal variations associated to a combination of hydrodynamic and anthropogenic pressures. The high proportions of microplastics found indicate that potential breakdown of plastics in the nearshore may take place in line with previous works. We prove that citizen science is a powerful tool in plastic research to monitor microplastics in the nearshore as it provides scientifically meaningful results while stimulating citizen engagement. Future studies may benefit from targeting specific scientific open questions by using the citizen science methodological approach presented here.
Lifetime based axial contrast enable simple 3D-STED imaging
Authors: Ma Yuanqing , Macmillan Alex , Yang Ying , Gaus Katharina
Published: March 2022

Stimulated Emission Depletion (STED) microscopy increase spatial image resolution by laterally sharpening the illumination profile of the confocal microscope. However, it remains compromised in axial resolution. To improve axial STED resolution, constructive interference of the STED depletion beam must be formed surrounding the focal plane to turn off the fluorophores beyond the focal plane. For isotropic 3D-STED resolution, this axial STED interference pattern must be overlayed with the doughnut STED beam at nanometer accuracy. Such optical configurations can be challenging in alignment. In this current work, we introduced a straightforward lifetime based axial contrast in STED microscope by imaging the samples on an ITO coated glass coverslip. The STED laser generates surface plasmon resonance on the ITO surface that enhanced the metal induced energy transfer MIET effect on the ITO surface. The enhanced MIET effect established a lifetime gradient with ∼20% dynamic range that extend for mor than 400 nm from the ITO surface. The axial contrast based on the lifetime gradient was directly used for 3D-STED imaging of tubulin fibers inside COS-7 cells, where the vertical displacement of single tubulin fiber was revealed. Lifetime gating could be applied to further improve lateral spatial resolution. Considering that most common implementation of STED microscopes uses pulsed lasers and timing electronics, there is no optical modification of the microscope is required in the current 3D-STED approach.
Holomorphic solutions of soliton equations
Authors: Domrin A.
Published: March 2022

We present a holomorphic version of the inverse scattering method for soliton equations of parabolic type in two-dimensional space-time. It enables one to construct examples of solutions holomorphic in both variables and study the properties of all such solutions. We show that every local holomorphic solution of any of these equations admits an analytic continuation to a globally meromorphic function of the spatial variable. We also discuss the role of the Riemann problem in the theory of integrable systems, solubility conditions for the Cauchy problem, the property of trivial monodromy for all solutions of the auxiliary linear system, and the Painlevé property for soliton equations.
IHGC-GAN: influence hypergraph convolutional generative adversarial network for risk prediction of late mild cognitive impairment based on imaging genetic data
Authors: Bi Xia-an , Li Lou , Wang Zizheng , Wang Yu , Luo Xun , Xu Luyun
Published: March 2022

Predicting disease progression in the initial stage to implement early intervention and treatment can effectively prevent the further deterioration of the condition. Traditional methods for medical data analysis usually fail to perform well because of their incapability for mining the correlation pattern of pathogenies. Therefore, many calculation methods have been excavated from the field of deep learning. In this study, we propose a novel method of influence hypergraph convolutional generative adversarial network (IHGC-GAN) for disease risk prediction. First, a hypergraph is constructed with genes and brain regions as nodes. Then, an influence transmission model is built to portray the associations between nodes and the transmission rule of disease information. Third, an IHGC-GAN method is constructed based on this model. This method innovatively combines the graph convolutional network (GCN) and GAN. The GCN is used as the generator in GAN to spread and update the lesion information of nodes in the brain region-gene hypergraph. Finally, the prediction accuracy of the method is improved by the mutual competition and repeated iteration between generator and discriminator. This method can not only capture the evolutionary pattern from early mild cognitive impairment (EMCI) to late MCI (LMCI) but also extract the pathogenic factors and predict the deterioration risk from EMCI to LMCI. The results on the two datasets indicate that the IHGC-GAN method has better prediction performance than the advanced methods in a variety of indicators.