Bacterial wilt is a serious problem affecting many important food crops. Recent studies have indicated that treatment with biotic or abiotic stress factors may increase the resistance of plants to ...bacterial infection. This study investigated the effects of magnesium oxide nanoparticles (MgO NP) on disease resistance in tomato plants against Ralstonia solanacearum, as well as its antibacterial activity. The roots of tomato seedlings were inoculated with R. solanacearum and then immediately treated with MgO NP; the treated plants showed very little inhibition of bacterial wilt. In contrast, when roots were drenched with a MgO NP suspension prior to inoculation with the pathogen, the incidence of disease was significantly reduced. Rapid generation of reactive oxygen species such as O₂ ⁻˙ radicals was observed in tomato roots treated with MgO NP. Further O₂ ⁻˙ was rapidly generated when tomato plant extracts or polyphenols were added to the MgO NP suspension, suggesting that the generation of O₂ ⁻˙ in tomato roots might be due to a reaction between MgO NP and polyphenols present in the roots. Salicylic acid‐inducible PR1, jasmonic acid‐inducible LoxA, ethylene‐inducible Osm, and systemic resistance‐related GluA were up‐regulated in both the roots and hypocotyls of tomato plants after treatment of the plant roots with MgO NP. Histochemical analyses showed that β‐1,3‐glucanase and tyloses accumulated in the xylem and apoplast of pith tissues of the hypocotyls after MgO NP treatment. These results indicate that MgO NP induces systemic resistance in tomato plants against R. solanacearum.
We present improved relative astrometry for stars within the central half parsec of our Galactic Center (GC) based on data obtained with the 10 m W. M. Keck Observatory from 1995 to 2017. The new ...methods used to improve the astrometric precision and accuracy include correcting for local astrometric distortions, applying a magnitude-dependent additive error, and more carefully removing instances of stellar confusion. Additionally, we adopt jackknife methods to calculate velocity and acceleration uncertainties. The resulting median proper motion uncertainty is 0.05 mas yr−1 for our complete sample of 1184 stars in the central 10″ (0.4 pc). We have detected 24 accelerating sources, 2.6 times more than the number of previously published accelerating sources, which extend out to 4″ (0.16 pc) from the black hole. Based on S0-2's orbit, our new astrometric analysis has reduced the systematic error of the supermassive black hole (SMBH) by a factor of 2. The linear drift in our astrometric reference frame is also reduced in the north-south direction by a factor of 4. We also find the first potential astrometric binary candidate S0-27 in the GC. These astrometric improvements provide a foundation for future studies of the origin and dynamics of the young stars around the SMBH, the structure and dynamics of the old nuclear star cluster, the SMBH's properties derived from orbits, and tests of general relativity in a strong gravitational field.
Measurement of the quantum-mechanical phase in quantum matter provides the most direct manifestation of the underlying abstract physics. We used resonant x-ray scattering to probe the relative phases ...of constituent atomic orbitals in an electronic wave function, which uncovers the unconventional Mott insulating state induced by relativistic spin-orbit coupling in the layered 5d transition metal oxide Sr2IrO4. A selection rule based on intra-atomic interference effects establishes a complex spin-orbital state represented by an effective total angular momentum = 1/2 quantum number, the phase of which can lead to a quantum topological state of matter.
We investigate the Schmid theorem, which states that if one has a tree level mechanism with a particle decaying to two particles and one of them decaying posteriorly to two other particles, the ...possible triangle singularity developed by the mechanism of elastic rescattering of two of the three decay particles does not change the cross section provided by the tree level. We investigate the process in terms of the width of the unstable particle produced in the first decay and determine the limits of validity and violation of the theorem. One of the conclusions is that the theorem holds in the strict limit of zero width of that resonance, in which case the strength of the triangle diagram becomes negligible compared to the tree level. Another conclusion, on the practical side, is that for realistic values of the width, the triangle singularity can provide a strength comparable or even bigger than the tree level, which indicates that invoking the Schmid theorem to neglect the triangle diagram stemming from elastic rescattering of the tree level should not be done. Even then, we observe that the realistic case keeps some memory of the Schmid theorem, which is visible in a peculiar interference pattern with the tree level.
Ion loss to space has played an important role in atmospheric escape and climate change on Mars because of intense solar activity during a younger, more active phase of the Sun. Although the ...existence of an intrinsic magnetic field on ancient Mars is also a key factor in ion loss, its effect remains unclear. Based on multispecies magnetohydrodynamics (MHD) simulations, we investigated processes and rates of ion loss from Mars under extreme solar conditions and the existence of a dipole field with different strengths. The effects of a dipole field on ion loss depend on whether the dipolar magnetic pressure is strong enough to sustain the solar wind dynamic pressure. When the dipole field is existent but weak, it facilitates the cusp outflow and increases the loss rates of molecular ions (O2+ and CO2+) by a factor of 6 through the high‐latitude magnetotail. When the dipole field is strong enough, the loss rates of molecular ions are decreased by 2 orders of magnitude, and peaks of the escape flux are located near the equatorial plane due to the magnetic reconnection in the northern‐dusk or southern‐dawn lobe regions. The pickup process on the extended oxygen corona created by the strong EUV flux contributes to the total O+ loss. Therefore, the effects of the dipole field are less pronounced for O+. Under more moderate solar EUV conditions, the effects on O+ loss can be stronger and thus contribute to climate change.
Plain Language Summary
It has been suggested that ancient Mars had an atmosphere thick enough to sustain liquid water on its surface, while present Mars only has a thin atmosphere. Ion loss to space is one of the important processes for the removal of the atmosphere because a younger Mars would have been exposed to much stronger solar activity. Over 4 Ga, Mars had an intrinsic magnetic field like that of the Earth. The existence of an intrinsic magnetic field changes the electromagnetic environment around the planet and affects the ion loss. We investigate the ion loss from Mars at approximately 4.5 Ga, assuming both the strong solar conditions and the existence of an intrinsic magnetic field using numerical simulations. The results show that the existence of the weak dipole field increases the loss of molecular ions such as O2+ and CO2+. Contrary to the weak intrinsic magnetic field, however, a strong intrinsic magnetic field substantially decreases the loss of molecular ions. The ion loss processes are also affected by the intrinsic magnetic field. These effects of the intrinsic magnetic field are less pronounced for O+ loss because of the extended O+ corona.
Key Points
A weak intrinsic magnetic field increases ion loss rates when the solar wind dynamic pressure exceeds the magnetic pressure (overpressure)
The existence of intrinsic magnetic field facilitates cusp outflows enabling more escape of molecular ions (O2+ and CO2+) by a factor of 6
In nonoverpressure cases, the ion loss rates decrease by 2 orders for molecular ions, but the effect is mild for O+ with extended corona
The association between pancreatic fat, obesity and metabolic disease is well-documented, and although a potentially exciting target for novel therapies, remains poorly understood. Non-invasive ...quantitative imaging-derived biomarkers can provide insights into pathophysiology and potentially provide robust trial endpoints for development of new treatments. In this review, we provide an overview of the pathophysiology of non-alcoholic fatty pancreas disease and associations with metabolic factors, obesity and diabetes. We then explore approaches to pancreatic fat quantification using ultrasound, CT and MRI, reviewing the strengths, limitations and current published evidence in the assessment of pancreatic fat. Finally, we explore the broader challenges of pancreatic fat quantification as we move toward translating these methods into the clinical setting.
Tests for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral ribonucleic acid (RNA) using reverse transcription polymerase chain reaction (RT-PCR) are pivotal to detecting current ...coronavirus disease (COVID-19) and duration of detectable virus indicating potential for infectivity.
We conducted an individual participant data (IPD) systematic review of longitudinal studies of RT-PCR test results in symptomatic SARS-CoV-2. We searched PubMed, LitCOVID, medRxiv, and COVID-19 Living Evidence databases. We assessed risk of bias using a QUADAS-2 adaptation. Outcomes were the percentage of positive test results by time and the duration of detectable virus, by anatomical sampling sites.
Of 5078 studies screened, we included 32 studies with 1023 SARS-CoV-2 infected participants and 1619 test results, from - 6 to 66 days post-symptom onset and hospitalisation. The highest percentage virus detection was from nasopharyngeal sampling between 0 and 4 days post-symptom onset at 89% (95% confidence interval (CI) 83 to 93) dropping to 54% (95% CI 47 to 61) after 10 to 14 days. On average, duration of detectable virus was longer with lower respiratory tract (LRT) sampling than upper respiratory tract (URT). Duration of faecal and respiratory tract virus detection varied greatly within individual participants. In some participants, virus was still detectable at 46 days post-symptom onset.
RT-PCR misses detection of people with SARS-CoV-2 infection; early sampling minimises false negative diagnoses. Beyond 10 days post-symptom onset, lower RT or faecal testing may be preferred sampling sites. The included studies are open to substantial risk of bias, so the positivity rates are probably overestimated.
Searching for space-time variations of the constants of Nature is a promising way to search for new physics beyond general relativity and the standard model motivated by unification theories and ...models of dark matter and dark energy. We propose a new way to search for a variation of the fine-structure constant using measurements of late-type evolved giant stars from the S star cluster orbiting the supermassive black hole in our Galactic Center. A measurement of the difference between distinct absorption lines (with different sensitivity to the fine structure constant) from a star leads to a direct estimate of a variation of the fine structure constant between the star's location and Earth. Using spectroscopic measurements of five stars, we obtain a constraint on the relative variation of the fine structure constant below 10^{-5}. This is the first time a varying constant of nature is searched for around a black hole and in a high gravitational potential. This analysis shows new ways the monitoring of stars in the Galactic Center can be used to probe fundamental physics.
Ion escape has played a key role in atmospheric loss on ancient Mars due to intense solar activity. Under the existence of a strong global intrinsic magnetic field, as expected on ancient Mars, ...differential flows between different ion species can be important for ion escape. To assess effects of differential flows, we here developed a new global multifluid magnetohydrodynamics model with a cubed sphere grid named Multifluid Atmospheric Escape Simulations Toward Real elucidatiOn (MAESTRO). A test simulation under present‐day Mars conditions showed solar wind‐Mars interactions, for example, plasma boundaries, ionospheric profiles, and tailward outflows, consistent with observations and simulation studies. We then conducted multifluid and multispecies simulations with six different dipole field strengths under ancient Mars conditions. The multifluid cases show asymmetric outflow distributions with respect to the solar wind convection electric field, as pointed out by previous studies on present‐day Mars. Compared with multispecies cases, the multifluid representation increases the escape rates of O2+ and CO2+ by more than two orders of magnitude in the strong dipole field cases where the cusp outflow is dominant. The O+ escape rate is slightly lower in the multifluid cases with no or weak dipole field due to suppression of ion pickup in the −E hemisphere, while it is reduced by one order of magnitude in the strongest dipole field case. The existence of a dipole field can reduce the total escape rate by a factor of six. The impact on atmospheric evolution is diminished but still significant.
Plain Language Summary
Mars lost a significant part of the atmosphere during its early period and experienced a drastic climate change. The escape of charged atmospheric particles to space, called ion escape, is a significant removal process of the atmosphere because the activity of the young Sun was much stronger and stripped out the upper atmosphere of early Mars more powerfully. However, it is thought that Mars once had an intrinsic magnetic field like Earth, which can affect the escape of charged particles via electromagnetic forces. To reproduce the realistic processes and morphology of ion escape under the presence of a planetary intrinsic magnetic field, we developed a new simulation model that treats each ion species as a separate fluid. The simulation results of the new model show much stronger molecular ion outflow from the ionosphere at relatively low altitudes compared to our previous studies. The outflow enhancement is more remarkable when a stronger intrinsic magnetic field is assumed. On the other hand, atomic ion escape from high altitudes is not affected largely. The new model indicates that the effects of a planetary intrinsic magnetic field on ion escape are reduced, though still of significance.
Key Points
A new global multifluid magnetohydrodynamics (MHD) model of solar wind‐Mars interactions with a cubed sphere grid system named Multifluid Atmospheric Escape Simulations Toward Real elucidatiOn is developed
The multispecies MHD cases underestimate outflows of ionospheric ions in strong dipole field cases where cusp outflow is important
The effects of the multifluid representation on the O+ escape rate are small in no and weak dipole field cases where ion pickup is dominant
Abstract Background MicroRNAs (miRNAs) are a class of small, well-conserved, non-coding RNAs that regulate the translation of RNAs. They have a role in biological and pathological process including ...cell differentiation, apoptosis, proliferation and metabolism. Since their discovery, they have been shown to have a potential role in cancer pathogenesis through their function as oncogenes or tumor suppressors. A substantial number of miRNAs show differential expression in esophageal cancer tissues, and so have been investigated for possible use in diagnosis. Furthermore, there is increasing interest in their use as prognostic markers and determining treatment response, as well as identifying their downstream targets and understanding their mode of action. Methods We analyzed the most recent studies on miRNAs in esophageal cancer and/or Barrett's esophagus (BE). The publications were identified by searching in PuBMed for the following terms: Barrett's esophagus and microRNA; esophageal cancer and microRNA. Results Four miRNAs (mi-R-25, -99a, -133a and -133b) showed good potential as diagnostic markers and interestingly five (mi-R-21, -27b, -126, - 143 and -145) appeared to be useful both as diagnostic and prognostic/predictive markers. Conclusion The data so far on miRNAs in esophageal carcinogenesis is promising but further work is required to determine whether miRNAs can be used as biomarkers, not only in the clinical setting or added to individualized treatment regimes but also in non-invasive test by making use of miRNAs identified in blood.
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