content variation
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2023 ◽  
Vol 83 ◽  
Author(s):  
Z. Hussain ◽  
Y. Sun ◽  
S. H. Shah ◽  
H. Khan ◽  
S. Ali ◽  
...  

Abstract Hybridization and Polyploidization are most common of the phenomenon observed in plants, especially in the genus Nicotiana leading to the duplication of genome. Although genomic changes associated with these events has been studied at various levels but the genome size and GC content variation is less understood because of absence of sufficient genomic data. In this study the flow cytometry technique was used to uncover the genome size and GC contents of 46 Nicotiana species and we compared the genomic changes associated with the hybridization events along evolutionary time scale. The genome size among Nicotiana species varied between 3.28 pg and 11.88 pg whereas GC contents varied between 37.22% and 51.25%. The tetraploid species in genus Nicotiana including section Polydiclae, Repandae, Nicotiana, Rustica and Sauveolentes revealed both up and downsizing in their genome sizes when compared to the sum of genomes of their ancestral species. The genome sizes of three homoploid hybrids were found near their ancestral species. Loss of large genome sequence was observed in the evolutionary more aged species (>10 Myr) as compared to the recently evolved one’s (<0.2 Myr). The GC contents were found homogenous with a mean difference of 2.46% among the Nicotiana species. It is concluded that genome size change appeared in either direction whereas the GC contents were found more homogenous in genus Nicotiana.


2022 ◽  
Vol 52 (1) ◽  
Author(s):  
Thalita Bordignon da Cunha ◽  
Antonio Vander Pereira ◽  
Francisco José da Silva Lédo ◽  
Rogério Figueiredo Daher ◽  
Juarez Campolina Machado

ABSTRACT: The objective of this study was to estimate sugar content variation (°Brix) in 95 accessions from the elephant grass germplasm active bank of Embrapa Dairy Cattle research center, located in Coronel Pacheco, MG, Brazil. The accessions with the highest sugar content were identified, and the effect of plant age on sugar concentration was evaluated. The experiment was conducted in randomized blocks design with two replications. Sugar content analysis occurred twice during the growth-cycle (at 70 and 100 days) along two points of the stem, one 30 cm from the base and the other at the midpoint. The analysis of variance considered the split plot model, with accessions as main plots and plant age as subplots. The means were compared using the Scott Knott test. While there was sugar content variation between accessions, increased plant age had no significant effect on the sugar content. However, some accessions did have a significant increase or decrease in sugar content as they aged. The highest and lowest mean sugar content was 6.96% (in the accession BAG80) and 4.03% (in the accession BAG13) °Brix, respectively.


Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sohrab Rahimi ◽  
Stavros Avramidis ◽  
Ciprian Lazarescu

Abstract Kiln drying is admittedly a significant value-adding step in timber processing where the importance of predicting moisture within a dried batch cannot be overemphasized. This study predicts and characterizes the moisture variation in kiln-dried wood based on the initial and target moisture values using polynomial models. Four polynomial models are used to correlate initial and final moisture characteristics. First model is linear while the three others are nonlinear. The robustness of the three best models is analyzed and a closed formula is proposed to evaluate the final moisture coefficient of variation based on the target moisture and initial moisture coefficient of variation. Three models could successfully characterize the final moisture variation with the best one showing an R 2 > 96%. However, the first (linear) model is the most resilient and, thus recommended for estimating final moisture variation.


2021 ◽  
Author(s):  
Shane L Hogle ◽  
Thomas Hackl ◽  
Randelle M Bundy ◽  
Jiwoon Park ◽  
Brandon Satinsky ◽  
...  

Prochlorococcus is one of the most abundant photosynthesizing organisms in the oligotrophic oceans. Gene content variation among Prochlorococcus populations in separate ocean basins often mirrors the selective pressures imposed by the region's distinct biogeochemistry. By pairing genomic datasets with trace metal concentrations from across the global ocean, we show that the genomic capacity for siderophore-mediated iron uptake is widespread in low-light adapted Prochlorococcus populations from iron-depleted regions of the oligotrophic Pacific and S. Atlantic oceans: Prochlorococcus siderophore consumers were absent in the N. Atlantic ocean (higher iron flux) but constituted up to half of all Prochlorococcus genomes from metagenomes in the N. Pacific (lower iron flux). Prochlorococcus siderophore consumers, like many other bacteria with this trait, also lack siderophore biosynthesis genes indicating that they scavenge exogenous siderophores from seawater. Statistical modeling suggests that the capacity for siderophore uptake is endemic to remote ocean regions where atmospheric iron fluxes are the smallest, particularly at deep chlorophyll maximum and primary nitrite maximum layers. We argue that abundant siderophore consumers at these two common oceanographic features could be a symptom of wider community iron stress, consistent with prior hypotheses. Our results provide a clear example of iron as a selective force driving the evolution of Prochlorococcus.


Author(s):  
Fernando Bernstein ◽  
Soudipta Chakraborty ◽  
Robert Swinney

Problem definition: We analyze a firm that sells repeatedly to a customer population over multiple periods. Although this setting has been studied extensively in the context of dynamic pricing—selling the same product in each period at a varying price—we consider intertemporal content variation, wherein the price is the same in every period, but the firm varies the content available over time. Customers learn their utility on purchasing and decide whether to purchase again in subsequent periods. The firm faces a budget for the total amount of content available during a finite planning horizon, and allocates content to maximize revenue. Academic/practical relevance: A number of new business models, including video streaming services and curated subscription boxes, face the situation we model. Our results show how such firms can use content variation to increase their revenues. Methodology: We employ an analytical model in which customers decide to purchase in multiple successive periods and a firm determines a content allocation policy to maximize revenue. Results: Using a lower bound approximation to the problem for a horizon of general length T, we show that, although the optimal allocation policy is not, in general, constant over time, it is monotone: content value increases over time if customer heterogeneity is low and decreases otherwise. We demonstrate that the optimal policy for this lower bound problem is either optimal or very close to optimal for the general T period problem. Furthermore, for the case of T = 2 periods, we show how two critical factors—the fraction of “new” versus “repeat” customers in the population and the size of the content budget—affect the optimal allocation policy and the importance of varying content value over time. Managerial implications: We show how firms that sell at a fixed price over multiple periods can vary content value over time to increase revenues.


Author(s):  
Zakka Izzatur Rahman Noor ◽  
Bambang Anggoro Soedjarno P ◽  
Pradita Octoviandiningrum Hadi

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