Influence of Light Conditions and Medium Composition on Morphophysiological Characteristics of Stevia rebaudiana Bertoni In Vitro and In Vivo

We investigated the influence of different conditions (light composition and plant growth regulators (PGRs) in culture media) on the morphophysiological parameters of Stevia rebaudiana Bertoni in vitro and in vivo. Both PGRs and the light spectra applied were found to significantly affect plant morphogenesis. During the micropropagation stage of S. rebaudiana, optimal growth, with a multiplication coefficient of 15, was obtained in an MS culture medium containing 2,4-epibrassinolide (Epin) and indole-3-acetic acid (IAA) at concentrations of 0.1 and 0.5 mg L−1, respectively. During the rooting stage, we found that the addition of 0.5 mg L−1 hydroxycinnamic acid (Zircon) to the MS medium led to an optimal root formation frequency of 85% and resulted in the formation of strong plants with well-developed leaf blades. Cultivation on media containing 0.1 mg L−1 Epin and 0.5 mg L−1 IAA and receiving coherent light irradiation on a weekly basis resulted in a 100% increase in the multiplication coefficient, better adventitious shoot growth, and a 33% increase in the number of leaves. S. rebaudiana microshoots, cultured on MS media containing 1.0 mg L−1 6-benzylaminopurine (BAP) and 0.5 mg L−1 IAA with red monochrome light treatments, increased the multiplication coefficient by 30% compared with controls (white light, media without PGRs).

Micropropagation and experimental field cultivation of Pulsatilla turczaninovii Kryl. et Serg. (Ranunculaceae)

Pulsatilla turczaninovii is an important medicinal plant, valued for high ornamental value of melliferous flowers. We assessed the efficiency of reproduction under in vitro conditions and the ex situ growth capacity of this important representative of the world flora. The seed germination percentage was assessed, followed by determination of micropropagation rate and rooting efficiency. Then, the possibility of plant development in three consecutive growing seasons was assessed. The in vitro germination percentage was approximately 55%. The highest multiplication coefficient, amounting to 5.17, was obtained on modified MS medium supplemented with 2.5 mg L−1 2iP and 1.0 mg L−1 IAA. Our study provided unique insight on biochemical background of root regeneration in P. turczaninovii. In comparison with standard auxin-supplemented rooting medium, the treatment with 1.0 mg L−1 level of ethylene precursor ACC elevated rooting by about 20%. The total content of soluble sugars was proved to be biomarker of rhizogenesis in the studied species. Their concentration was positively correlated with rooting efficiency, while a level of phenolic was positively correlated with the length of regenerated roots, and their number per rosette. The cultivation of the acclimatized material was successfully carried out and was evaluated over three subsequent years. In the third year of cultivation, the plants entered the stage of generative development and most of them bloomed profusely.

Examinations for creating an image of unacquired dose from the images of two types of dose in digital radiography

BACKGROUND: Digital radiography (DR) is grayscale adjustable and it can be unclear whether an acquired DR image is captured with the minimum radiation dose required. It is necessary to make an image of the amount of noise when taken at a lower dose than the acquired image, without increased exposure. OBJECTIVE: To examine whether an image of unacquired dose can be created from two types of dose DR images acquired using a phantom. METHODS: To create an additive image from two images of different doses, the pixel value of one image is multiplied by a coefficient and added to the other. The normalized noise power spectra (NNPS) of the normal image and the additive image with the same signal-to-noise ratio (SNR) are compared. The image noise of the unacquired doses is estimated from the graph changes of the pixel values and standard deviations of two images. The error between the SNR of the image obtained by changing the dose and the estimated SNR is measured. We propose a multiplication coefficient calculation formula that theoretically adjusts the additive image to the target SNR. The SNR error of the image created based on this formula is measured. RESULTS: The NNPS curves of the additive and normal images show a difference on the high frequency side. According to the statistics considering the preset of mAs value, there is no significant difference at 85%. The SNR estimation error is approximately 1%. The SNR error of the additive image created based on the formula is approximately 5%. CONCLUSION: The noise of the image of unacquired dose can be estimated, and the additive image adjusted to this value can be considered equivalent to the image taken at the actual dose.

On the Design of an Energy Efficient Digital IIR A-Weighting Filter Using Approximate Multiplication

This paper presents a new A-weighting filter’s design and explores the potential of using approximate multiplication for low-power digital A-weighting filter implementation. It presents a thorough analysis of the effects of approximate multiplication, coefficient quantization, the order of first-order sections in the filter’s cascade, and zero-pole pairings on the frequency response of the digital A-weighting filter. The proposed A-weighting filter was implemented as a sixth-order IIR filter using approximate odd radix-4 multipliers. The proposed filter was synthesized (Verilog to GDS) using the Nangate45 cell library, and MATLAB simulations were performed to verify the designed filter’s magnitude response and performance. Synthesis results indicate that the proposed design achieves nearly 70% reduction in energy (power-delay product) with a negligible deviation of the frequency response from the floating-point implementation. Experiments on acoustic noise suggest that the proposed digital A-weighting filter can be deployed in environmental noise measurement applications without any notable performance degradation.

Dynamics of COVID-19 pandemic at constant and time-dependent contact rates

We constructed a simple Susceptible–Infected–Infectious–Excluded model of the spread of COVID-19. The model is parametrised only by the average incubation period, τ, and two rate parameters: contact rate, rC, and exclusion rate, rE. The rates can be manipulated by non-therapeutic interventions and determine the basic reproduction number, R = rC/rE, and, together with τ, the daily multiplication coefficient at the early exponential phase, β. Initial β determines the reduction of rC required to contain epidemic spread. In the long-term, we consider a scenario based on typical social behaviours, in which rC first decreases in response to a surge of daily new cases, forcing people to self-isolate, and then slowly increases when people gradually accept higher risk. Consequently, initial abrupt epidemic spread is followed by a plateau and slow regression. This scenario, although economically and socially devastating, will grant time to develop, produce, and distribute a vaccine, or at least limit daily cases to a manageable number.

Dynamics of COVID-19 pandemic at constant and time-dependent contact rates

We constructed a simple Susceptible−Exposed–Infectious–Removed model of the spread of COVID-19. The model is parametrised only by the average incubation period, τ, and two rate parameters: contact rate, β, and exclusion rate, γ. The rates depend on nontherapeutic interventions and determine the basic reproduction number, R0 = β/γ, and, together with τ, the daily multiplication coefficient in the early exponential phase, θ. Initial R0 determines the reduction of β required to contain the spread of the epidemic. We demonstrate that introduction of a cascade of multiple exposed states enables the model to reproduce the distributions of the incubation period and the serial interval reported by epidemiologists. Using the model, we consider a hypothetical scenario in which β is modulated solely by anticipated changes of social behaviours: first, β decreases in response to a surge of daily new cases, pressuring people to self-isolate, and then, over longer time scale, β increases as people gradually accept the risk. In this scenario, initial abrupt epidemic spread is followed by a plateau and slow regression, which, although economically and socially devastating, grants time to develop and deploy vaccine or at least limit daily cases to a manageable number.

Shoot multiplication via elongated stem node culture under darkness: a novel method in micropropagation of Paphiopedilum villosum

Paphiopedilum villosum is a beautiful orchid species and has high value in trade; however, this is one of the most difficult to propagate orchids. So far, there has been very little publication on micropropagation. In this study, the effects of plant growth regulators on shoot regeneration from stem node culture of elongated P. villosum shoots in the darkness were investigated. Shoots (1.5 cm) were elongated and produced individual stem nodes under darkness condition for 3 months. Stem nodes were cultured on SH medium and supplemented with individually BA, KIN or TDZ to investigate shoot regeneration. The shoot multiplication rate was also recorded in this study. The highest stem node was observed in the dark with 5.25 cm in the height and the number of stem nodes were 3 stem nodes/shoot. The isolated stem node was cultured on SH medium supplemented with 30 g/L sucrose, 8 g/L agar, 1 g/L charcoal and different concentrations of BA, KIN, TDZ. The results observed after 3 months showed that the best shoot regeneration rate (85%) and highest shoot multiplication coefficient (6.6 shoots/stem node) was obtained when shoots derived from stem node were cultured on SH medium supplemented with 0.5 mg/L TDZ, 30 g/L sucrose, 8 g/L agar and 1 g/L charcoal. Those shoots obtained in the above treatments were subcultured on MS medium supplemented with 0.3 mg/L NAA for rooting and gave the highest number of roots (6.6 roots/shoot) after 1 month; and these plantlets were acclimatized in Taiwan sphagnum moss and transferred into greenhouse with the best survival rate (100%) after 3 months.

Effects of Different Paclobutrazol-Cultar Concentrations on the Micropropagation of Sugarcane (Saccharum Officinarum) Variety CPCL99-4455

Sugarcane (Saccharum officinarum), being an important cash crop in Belize, accounts for 60% of agricultural exports providing employment for thousands of Belizeans. This research was carried out to determine the effects of different Paclobutrazol (PBZ-Cultar) concentrations used in the culture media on in vitro multiplication of sugarcane variety CPCL99-4455. Three PBZ-Cultar concentrations were tested and compared with the control. The parameters evaluated to determine the effects of PBZ-Cultar were average height, number of dead leaves and multiplication coefficient. The plants from this experiment were planted in the acclimatization phase to determine if the use of PBZ-Cultar had any effect of the growth and development of the plants ex vitro. The results revealed that the culture medium supplemented with 0.08% PBZ-Cultar concentration had the best results both in the multiplication phase as well as the acclimatization phase.