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Plants memorize events associated with environmental fluctuations. The integration of environmental signals into molecular memory allows plants to cope with future stressors more efficiently—a phenomenon that is known as 'priming'. Primed plants are more resilient to environmental stresses than non-primed plants, as they are capable of triggering more robust and faster defence responses. Interestingly, exposure to various forms of mechanical stimuli (e.g. touch, wind, or sound vibration) enhances plants' basal defence responses and stress tolerance. Thus, mechanostimulation appears to be a potential priming method and a promising alternative to chemical-based priming for sustainable agriculture. According to the currently available method, mechanical treatment needs to be repeated over a month to alter plant growth and defence responses. Such a long treatment protocol restricts its applicability to fast-growing crops. To optimize the protocol for a broad range of crops, we need to understand the molecular mechanisms behind plant mechanoresponses, which are complex and depend on the frequency, intervals, and duration of the mechanical treatment. In this review, we synthesize the molecular underpinnings of plant mechanoperception and signal transduction to gain a mechanistic understanding of the process of mechanostimulated priming. [ABSTRACT FROM AUTHOR]

We have extensively studied the broad--band X-ray spectra of the source ESO 141–G055 using all available XMM–Newton and NuSTAR observations. We detect a prominent soft excess below |$2\rm \, \, {\rm keV}$|⁠ , a narrow Fe line, and a Compton hump (⁠|$\gt 10\rm \, \, {\rm keV}$|⁠). The origin of the soft excess is still debated. We used two models to describe the soft excess: the blurred reflection from the ionized accretion disc and the intrinsic thermal Comptonization model. We find that both of these models explain the soft excess equally well. We confirm that we do not detect any broad Fe line in the X-ray spectra of this source, although both the physical models prefer a maximally spinning black hole scenario (a > 0.96). This may mean that either the broad Fe line is absent or blurred beyond detection. The Eddington rate of the source is estimated to be |$\lambda _{\rm \, Edd}\sim 0.31$|⁠. In the reflection model, the Compton hump has a contribution from both ionized and neutral reflection components. The neutral reflector which simultaneously describes the narrow Fe K α and the Compton hump has a column density of |$N_{\rm H} \ge 7\times 10^{24} \, \rm cm^{-2}$|⁠. In addition, we detect a partially covering ionized absorption with ionization parameter |$\log \xi /\rm \, erg\, cm\, s^{-1}$|  =  |$0.1^{+0.1}_{-0.1}$| and column density |$N_{\rm H} =20.6^{+1.0}_{-1.0}\times 10^{22} \, \rm cm^{-2}$| with a covering factor of |$0.21^{+0.01}_{-0.01}$|⁠. [ABSTRACT FROM AUTHOR]

We have investigated the nature and origin of the Fe K emission lines in Mrk 205 using observations with Suzaku and XMM–Newton , aiming to resolve the ambiguity between a broad emission line and multiple unresolved lines of higher ionization. We detect the presence of a narrow Fe K α emission line along with a broad-band Compton reflection hump at energies |$E\gt 10\rm \, \, {\rm keV}$|⁠. These are consistent with reflected emission of hard X-ray photons off a Compton-thick material of |$N_{\rm H}\ge 2.15\times 10^{24}\rm \, \, {\rm cm^{-2}}$|⁠. In addition we detect a partially covering ionized absorption with ionization parameter |$\log (\xi /\rm \, erg\, cm\, s^{-1})=1.9_{-0.5}^{+0.1}$|⁠ , column density |$N_{\rm H}=(5.6_{-1.9}^{+2.0})\times 10^{22}\rm \, \, {\rm cm^{-2}}$|⁠ , and a covering factor of |$0.22_{-0.06}^{+0.09}$|⁠. We detect the presence of emission arising out of ionized disc reflection contributing in the soft and hard X-rays consistently in all the observations. We however, could not definitely ascertain the presence of a relativistically broadened Fe line in the X-ray spectra. Using relativistic reflection models, we found that the data are unable to statistically distinguish between the scenarios when the supermassive black hole is non-rotating and when it is maximally spinning. Using the disc reflection model we also find that the accretion disc of the active galactic nucleus may be truncated at a distance 6 R G < R < 12 R G, which may suggest why there may not be any broad Fe line. The Eddington rate of the source is low (λEdd = 0.03), which points to an inefficient accretion, possibly due to a truncated disc. [ABSTRACT FROM AUTHOR]

We have carried out a systematic X-ray spectral analysis of a sample of low-luminosity quasars (LLQSO) to investigate the nature of the central engines of these sources. The optically selected LLQSO sample consists of close, known bright active galactic nuclei (AGN) which serves as an important link between the powerful quasars at higher redshift and local Seyfert galaxies. We find that although the bolometric luminosities of the LLQSOs are lower than those of the higher redshift quasars by almost an order of magnitude, their distribution of the Eddington rate $$\lambda _{\rm \, Edd}$$ is similar. We detect a strong anticorrelation between αOX and $$L_{2500 \mathring{\rm A}}$$, as has also been detected in several other quasar studies with large sample sizes, indicating that as the UV luminosity of the source increases, the X-ray luminosity decreases. We do not detect any significant neutral obscuration ($$N_{\rm H}\ge 10^{22}\rm \, \, {\rm cm^{-2}}$$) in the X-ray spectra of the LLQSOs, and hence rule out obscuration as a possible cause for their lower luminosity. We conclude that the central engines of the LLQSOs function similarly to those of the higher redshift quasars, and the difference is possibly because of the fact that the LLQSOs have lower black hole masses. We do not find any correlation between the molecular gas in the host galaxies and accretion states of the AGN. This indicates that the presence of molecular gas in the host galaxies of the LLQSOs does not significantly influence the instantaneous accretion rates of their SMBHs. [ABSTRACT FROM AUTHOR]

We present a broad-band spectral study of the radio-loud narrow-line Seyfert 1 galaxy 1H 0323+342 based on multi-epoch observations performed with Nuclear Spectroscopic Telescope Array on 2014 March 15, and two simultaneous observations performed with Suzaku and Swift on 2009 July 26 and 2013 March 1. We found the presence of a strong soft X-ray excess emission, a broad but weak Fe line and hard X-ray excess emission. We used the blurred reflection (relxill) and the intrinsic disc Comptonization (optxagnf), two physically motivated models, to describe the broad-band spectra and to disentangle the disc/corona and jet emission. The relxill model is mainly constrained by the strong soft X-ray excess although the model failed to predict this excess when fitted above $3\rm \,\,{\rm keV}$ and extrapolated to lower energies. The joint spectral analysis of the three data sets above $3\rm \,\,{\rm keV}$ with this model resulted in a high black hole spin (a > 0.9) and moderate reflection fraction R ∼ 0.5. The optxagnf model fitted to the two simultaneous data sets resulted in an excess emission in the ultraviolet (UV) band. The simultaneous UV-to-hard X-ray spectra of 1H 0323+342 are best described by a model consisting of a primary X-ray power-law continuum with Γ ∼ 1.8, a blurred reflection component with R ∼ 0.5, Comptonized disc emission as the soft X-ray excess, optical/UV emission from a standard accretion disc around a black hole of mass ∼107M⊙ and a steep power law (Γ ∼ 3–3.5) component, most likely the jet emission in the UV band. The fractional rms variability spectra suggest that both the soft excess and the power-law component are variable in nature. [ABSTRACT FROM AUTHOR]

Being sessile, plants continuously deal with their dynamic and complex surroundings, identifying important cues and reacting with appropriate responses. Consequently, the sensitivity of plants has evolved to perceive a myriad of external stimuli, which ultimately ensures their successful survival. Research over past centuries has established that plants respond to environmental factors such as light, temperature, moisture, and mechanical perturbations (e.g. wind, rain, touch, etc.) by suitably modulating their growth and development. However, sound vibrations (SVs) as a stimulus have only started receiving attention relatively recently. SVs have been shown to increase the yields of several crops and strengthen plant immunity against pathogens. These vibrations can also prime the plants so as to make them more tolerant to impending drought. Plants can recognize the chewing sounds of insect larvae and the buzz of a pollinating bee, and respond accordingly. It is thus plausible that SVs may serve as a long-range stimulus that evokes ecologically relevant signaling mechanisms in plants. Studies have suggested that SVs increase the transcription of certain genes, soluble protein content, and support enhanced growth and development in plants. At the cellular level, SVs can change the secondary structure of plasma membrane proteins, affect microfilament rearrangements, produce Ca2+ signatures, cause increases in protein kinases, protective enzymes, peroxidases, antioxidant enzymes, amylase, H+-ATPase / K+ channel activities, and enhance levels of polyamines, soluble sugars and auxin. In this paper, we propose a signaling model to account for the molecular episodes that SVs induce within the cell, and in so doing we uncover a number of interesting questions that need to be addressed by future research in plant acoustics. [ABSTRACT FROM AUTHOR]