Abstract
The Solar Dynamics Observatory (SDO), a NASA multispectral decade-long mission that has been daily producing terabytes of observational data from the Sun, has been recently used as a use ...case to demonstrate the potential of machine-learning methodologies and to pave the way for future deep space mission planning. In particular, the idea of using image-to-image translation to virtually produce extreme ultraviolet channels has been proposed in several recent studies, as a way to both enhance missions with fewer available channels and to alleviate the challenges due to the low downlink rate in deep space. This paper investigates the potential and the limitations of such a deep learning approach by focusing on the permutation of four channels and an encoder–decoder based architecture, with particular attention to how morphological traits and brightness of the solar surface affect the neural network predictions. In this work we want to answer the question: can synthetic images of the solar corona produced via image-to-image translation be used for scientific studies of the Sun? The analysis highlights that the neural network produces high-quality images over 3 orders of magnitude in count rate (pixel intensity) and can generally reproduce the covariance across channels within a 1% error. However, the model performance drastically diminishes in correspondence to extremely high energetic events like flares, and we argue that the reason is related to the rareness of such events posing a challenge to model training.
The activity of the Sun alternates between a solar minimum and a solar maximum, the former corresponding to a period of “quieter” status of the heliosphere. During solar minimum, it is in principle ...more straightforward to follow eruptive events and solar wind structures from their birth at the Sun throughout their interplanetary journey. In this paper, we report analysis of the origin, evolution, and heliospheric impact of a series of solar transient events that took place during the second half of August 2018, that is, in the midst of the late declining phase of Solar Cycle 24. In particular, we focus on two successive coronal mass ejections (CMEs) and a following high-speed stream (HSS) on their way toward Earth and Mars. We find that the first CME impacted both planets, whilst the second caused a strong magnetic storm at Earth and went on to miss Mars, which nevertheless experienced space weather effects from the stream interacting region preceding the HSS. Analysis of remote-sensing and in-situ data supported by heliospheric modeling suggests that CME–HSS interaction resulted in the second CME rotating and deflecting in interplanetary space, highlighting that accurately reproducing the ambient solar wind is crucial even during “simpler” solar minimum periods. Lastly, we discuss the upstream solar wind conditions and transient structures responsible for driving space weather effects at Earth and Mars.
Prostate cancer (PCa) represents the second most common cancer in men and affects millions worldwide. Chemotherapy is a common treatment for PCa but the development of resistance is often a problem ...during therapy. NRF2 (nuclear factor erythroid 2‐related factor 2) is one of the major transcription factors regulating antioxidant enzymes and is also involved with drug efflux and detoxification. Cancer cells submitted to chemotherapy often promote NRF2 activation to benefit themselves with the cytoprotective response. Here, we found that DU145 and PC3 PCa cell lines have different responses regarding NRF2 activation, when subjected to arsenite‐induced stress, even in the presence of MG132, a proteasome inhibitor. We also observed that only in PC3 cells treated with arsenite, NRF2 was able to translocate to the nucleus. To better understand the role of NRF2 in promoting chemoresistance, we performed CRISPR knockout of NRF2 (NKO) in DU145 and PC3 cells. The effectiveness of the knockout was confirmed through the downregulation of NRF2 targets (p < 0.0001). PC3 NKO cells exhibited higher levels of reactive oxygen species (ROS) compared to wild‐type cells (p < 0.0001), while this alteration was not observed in DU145 NKO cells. Despite no modulation in ROS content, a lower IC50 value (p < 0.05) for cisplatin was observed in DU145 NKO cells, suggesting that the knockout sensitized the cells to the treatment. Besides, the treatment of DU145 NKO with cisplatin led cells to apoptosis as observed by the increased levels of PARP1 cleavage (p < 0.05), possibly triggered by increased DNA damage. Reduced levels of KU70 and phospho‐CHK2 (p < 0.05) were also detected. The data presented here support that NRF2 is a mediator of oncogenesis and could be a potential target to sensitize PCa cells to chemotherapy, reinforcing the importance of knowing the specific genetic and biochemical characteristics of the cancer cells for a more effective approach against cancer.
Galactinol synthase (EC 2.4.1.123; GolS) catalyzes the first step in the synthesis of raffinose family oligosaccharides (RFOs). Their accumulation in response to abiotic stresses implies a role for ...RFOs in stress adaptation. In this study, the expression patterns of three isoforms of
galactinol synthase (
CaGolS1-2-3) from
Coffea arabica were evaluated in response to water deficit, salinity and heat stress. All
CaGolS isoforms were highly expressed in leaves while little to no expression were detected in flower buds, flowers, plagiotropic shoots, roots, endosperm and pericarp of mature fruits. Transcriptional analysis indicated that the genes were differentially regulated under water deficit, high salt and heat stress.
CaGolS1 isoform is constitutively expressed in plants under normal growth conditions and was the most responsive during all stress treatments.
CaGolS2 is unique among the three isoforms in that it was detected only under severe water deficit and salt stresses.
CaGolS3 was primarily expressed under moderate and severe drought. This isoform was induced only at the third day of heat and under high salt stress. The increase in
GolS transcription was not reflected into the amount of galactinol in coffee leaves, as specific glycosyltransferases most likely used galactinol to transfer galactose units to higher homologous oligosaccharides, as suggested by the increase of raffinose and stachyose during the stresses.
► Three
galactinol synthases cDNAs from
Coffea arabica named
CaGolS1-2-3 were isolated. ► All
CaGolS isoforms were highly and predominantly expressed in leaves. ► The isoforms were differentially regulated under water deficit, salinity and heat stresses. ► The increase in
GolS transcription was not related to the galactinol accumulation in leaves. ► The accumulation of raffinose and stachyose depends on the type and level of the stress.
Abstract
We investigate the effects of the evolutionary processes in the internal magnetic structure of two interplanetary coronal mass ejections (ICMEs) detected in situ between 2020 November 29 and ...December 1 by the Parker Solar Probe (PSP). The sources of the ICMEs were observed remotely at the Sun in EUV and subsequently tracked to their coronal counterparts in white light. This period is of particular interest to the community as it has been identified as the first widespread solar energetic particle event of solar cycle 25. The distribution of various solar and heliospheric-dedicated spacecraft throughout the inner heliosphere during PSP observations of these large-scale magnetic structures enables a comprehensive analysis of the internal evolution and topology of such structures. By assembling different models and techniques, we identify the signatures of interaction between the two consecutive ICMEs and the implications for their internal structure. We use multispacecraft observations in combination with a remote-sensing forward modeling technique, numerical propagation models, and in situ reconstruction techniques. The outcome, from the full reconciliations, demonstrates that the two coronal mass ejections (CMEs) are interacting in the vicinity of the PSP. Thus, we identify the in situ observations based on the physical processes that are associated with the interaction and collision of both CMEs. We also expand the flux rope modeling and in situ reconstruction technique to incorporate the aging and expansion effects in a distorted internal magnetic structure and explore the implications of both effects in the magnetic configuration of the ICMEs.
The magnetic field configurations associated with interplanetary coronal mass ejections (ICMEs) are the
in situ
manifestations of the entrained magnetic structure associated with coronal mass ...ejections (CMEs). We present a comprehensive study of the internal magnetic field configurations of ICMEs observed at 1 AU by the
Wind
mission during 1995 – 2015. The goal is to unravel the internal magnetic structure associated with the ICMEs and establish the signatures that validate a flux-rope structure. We examine the expected magnetic field signatures by simulating spacecraft trajectories within a simple flux rope,
i.e.
, with circular–cylindrical (CC) helical magnetic field geometry. By comparing the synthetic configurations with the 353 ICME
in situ
observations, we find that only 152 events (
F
r
) display the clear signatures of an expected axial-symmetric flux rope. Two more populations exhibit possible signatures of flux rope; 58 cases (
F
−
) display a small rotation (
<
90
∘
) of the magnetic field direction, interpreted as a large separation of the spacecraft from the center, and, 62 cases (
F
+
) exhibit larger rotations, possibly arising from more complex configuration. The categories,
C
x
(14%) and
E
events (9%), reveal signatures of complexity possibly related with evolutionary processes. We then reconstruct the flux ropes assuming CC geometry. We examine the orientation and geometrical properties during the solar activity levels at the end of Solar Cycle 22 (SC22), SC23 and part of SC24. The orientation exhibits solar cycle trends and follow the heliospheric current sheet orientation. We confirm previous studies that found a Hale cycle dependence of the poloidal field reversal. By comparing our results with the occurrence of CMEs with large angular width (
AW
>
60
∘
) we find a broad correlation suggesting that such events are highly inclined CMEs. The solar cycle distribution of bipolar
vs.
unipolar
B
z
configuration confirms that the CMEs may remove solar cycle magnetic field and helicity.
Among the current challenges in space weather, one of the main ones is to forecast the internal magnetic configuration within interplanetary coronal mass ejections (ICMEs). The classification of such ...an arrangement is essential to predict geomagnetic disturbances. When a monotonic and coherent magnetic configuration is observed, it is associated with the result of a spacecraft crossing a large flux rope with the topology of helical magnetic field lines. This article applies machine learning and a current physical flux rope analytical model to identify and further understand the internal structure of ICMEs. We trained an image recognition artificial neural network with analytical flux rope data, generated from the range of many possible trajectories within a cylindrical (circular and elliptical cross-section) model. The trained network was then evaluated against the observed ICMEs from Wind during 1995–2015.
The methodology developed in this article can classify 84% of simple real cases correctly and has a 76% success rate when extended to a broader set with 5% noise applied, although it does exhibit a bias in favor of positive flux rope classification. As a first step towards a generalizable classification and parameterization tool, these results are promising. With further tuning and refinement, our model presents a strong potential to evolve into a robust tool for identifying flux rope configurations from in situ data.
Geomagnetic disturbance forecasting is based on the identification of solar wind structures and accurate determination of their magnetic field orientation. For nowcasting activities, this is ...currently a tedious and manual process. Focusing on the main driver of geomagnetic disturbances, the twisted internal magnetic field of interplanetary coronal mass ejections (ICMEs), we explore a convolutional neural network’s (CNN) ability to predict the embedded magnetic flux rope’s orientation once it has been identified from
in situ
solar wind observations. Our work uses CNNs trained with magnetic field vectors from analytical flux rope data. The simulated flux ropes span many possible spacecraft trajectories and flux rope orientations. We train CNNs first with full duration flux ropes and then again with partial duration flux ropes. The former provides us with a baseline of how well CNNs can predict flux rope orientation while the latter provides insights into real-time forecasting by exploring how accuracy is affected by percentage of flux rope observed. The process of casting the physics problem as a machine learning problem is discussed as well as the impacts of different factors on prediction accuracy such as flux rope fluctuations and different neural network topologies. Finally, results from evaluating the trained network against observed ICMEs from Wind during 1995–2015 are presented.
ABSTRACT Downy mildew is one of the main foliar diseases affecting melon plants during the rainy season in the Northeast region of Brazil. Silicon (Si) application has emerged as an alternative ...method for pathogen control, forming physical barriers and activating defense mechanisms in plants. The objective of this study was to reduce the severity of downy mildew in melon plants during the rainy season through foliar application of Si. The treatments consisted of five rates (0, 0.25, 0.5, 1, and 2 L ha-1) of potassium silicate (12% Si and 15% potassium) applied from May to July 2022, with four replications. Disease severity was assessed using rating scales, chlorophyll contents, and transient chlorophyll a fluorescence (OJIP). The rate of 2 L ha-1 resulted in the best results by delaying pathogen development in leaves with disease incidence. Disease severity decreased to 68.27% and chlorophyll a, b, and total increased by 8.21%, 13.86%, and 9.72%, respectively. Si application resulted in beneficial changes in the following OJIP test parameters: ABS/RC, TR0/RC, ET0/RC, ABS/CS0, and TR0/CS0. During periods of high rainfall intensity and mild temperatures, Si application to melon plants reduces downy mildew severity and protects chlorophylls, enhancing the absorption flux (ABS) and electron storage (TR0) and transport (ET0).
RESUMO O míldio é umas das principais doenças foliares que acomete o meloeiro durante o período chuvoso na região Nordeste do Brasil. O silício (Si) tem se destacado como um método alternativo para o controle de patógenos tanto por constituir barreira físicas, como na ativação de mecanismos de defesa da planta. Assim, objetivou-se com este trabalho avaliar a severidade de míldio em meloeiro durante período chuvoso com aplicações foliares de Si. Durante as chuvas, nos meses de maio a julho de 2022 realizaram-se duas pulverizações de silicato de potássio (12% de Si e 15% de potássio) nas doses de 0; 0,25; 0,50; 1,0 e 2,0 L ha-1, com quatro repetições por dose. Realizaram-se avaliações da severidade do míldio em escalas de notas, índices de clorofila e fluorescência transiente da clorofila a (OJIP). A dose de 2,0 L ha-1 proporcionou melhores resultados retardando o desenvolvimento do patógeno em folhas com incidência da doença. Houve diminuição na severidade da doença de até 68,27%, além do aumento nos índices de clorofila a, b e total, em 8,21%, 13,86% e 9,72%, respectivamente. Além disso, o Si promoveu alterações benéficas nos parâmetros do teste OJIP: ABS/RC; TR0/RC; ET0/RC; ABS/CS0 e TR0/CS0. Durante períodos de alta intensidade de chuvas e temperaturas amenas, a aplicação de Si em meloeiro reduz a severidade do míldio e protege as clorofilas, resultando em maior absorção (ABS), armazenamento (TR0) e transporte de elétrons (ET0).
Redefining Flux Ropes in Heliophysics Nieves-Chinchilla, Teresa; Pal, Sanchita; Salman, Tarik M ...
Frontiers in astronomy and space sciences,
03/2023, Letnik:
10
Journal Article
Recenzirano
Odprti dostop
Magnetic flux ropes manifest as twisted bundles of magnetic field lines. They carry significant amounts of solar mass in the heliosphere. This paper underlines the need to advance on the fundamental ...understanding of heliospheric flux ropes and provides the motivation to significantly improve the status quo of flux rope research through the novel and requisite approaches. It briefly discusses the current understanding of flux rope formation and evolution, and summarizes the strategies that have been undertaken to understand the dynamics of heliospheric structures. The challenges and recommendations put forward to address them are expected to broaden the in-depth knowledge of our nearest star, its dynamics, and its role in its region of influence, the heliosphere.
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