Improving permeability semivariograms with transition probability models of hierarchical sedimentary architecture derived from outcrop analog studies

2005 ◽  
Vol 41 (7) ◽  
Author(s):  
Zhenxue Dai ◽  
Robert W. Ritzi ◽  
David F. Dominic
Keyword(s):  
Transition Probability ◽  
Probability Models ◽  
Sedimentary Architecture ◽  
Outcrop Analog

scholarly journals Cell Cycle Commitment and the Origins of Cell Cycle Variability

2021 ◽  
Vol 9 ◽  
Author(s):  
Robert F. Brooks
Keyword(s):  
Cell Cycle ◽  
Dynamic Behavior ◽  
Transition Probability ◽  
Molecular Networks ◽  
Probability Models ◽  
Clonal Population ◽  
Restriction Point ◽  
The Relationship ◽  
Mitogenic Signal

Exit of cells from quiescence following mitogenic stimulation is highly asynchronous, and there is a great deal of heterogeneity in the response. Even in a single, clonal population, some cells re-enter the cell cycle after a sub-optimal mitogenic signal while other, seemingly identical cells, do not, though they remain capable of responding to a higher level of stimulus. This review will consider the origins of this variability and heterogeneity, both in cells re-entering the cycle from quiescence and in the context of commitment decisions in continuously cycling populations. Particular attention will be paid to the role of two interacting molecular networks, namely the RB-E2F and APC/CCDH1 “switches.” These networks have the property of bistability and it seems likely that they are responsible for dynamic behavior previously described kinetically by Transition Probability models of the cell cycle. The relationship between these switches and the so-called Restriction Point of the cell cycle will also be considered.

Modeling of vehicle driving conditions using transition probability models

2011 ◽  
Author(s):  
Kevin McDonough ◽  
Ilya Kolmanovsky ◽  
Dimitar Filev ◽  
Diana Yanakiev ◽  
Steve Szwabowski ◽  
...  
Keyword(s):  
Transition Probability ◽  
Probability Models ◽  
Driving Conditions

scholarly journals Biological integrity enhances the qualitative effectiveness of conditional mice-oak mutualisms

2021 ◽  
Author(s):  
Mario Díaz ◽  
Teresa Morán-López ◽  
Jesús Sánchez-Dávila ◽  
Ignasi Torre ◽  
Alvaro Navarro-Castilla ◽  
...  
Keyword(s):  
Seed Dispersal ◽  
Predation Risk ◽  
Large Scale ◽  
Transition Probability ◽  
Joint Effect ◽  
Tree Regeneration ◽  
Probability Models ◽  
Scatter Hoarding ◽  
Extrinsic Factors ◽  
Dispersal Effectiveness

Scatter-hoarding decisions by rodents are key for the long-term maintenance of scattered tree populations. Decisions are determined by seed value, competition and predation risk, so that they can be influenced by the integrity of the biological system composed by trees, rodents, ungulate competitors, and rodent predators. We manipulate and model the oak-mice interaction in a Spanish dehesa, an anthropogenic savanna system suffering chronic tree regeneration failure, and quantify the joint effect of intrinsic and extrinsic factors on acorn dispersal effectiveness. First, we conducted a large-scale cafeteria field experiment, where we modified ungulate presence and predation risk, and followed mouse scatter-hoarding decisions under contrasting levels of moonlight and acorn availability. Then, we estimated the net effects of competition and risk by means of transition probability models that simulated mouse scatter-hoarding decisions according to the environmental context.  Our results show that suboptimal conditions for mice balance the interaction towards the mutualism as they force mice to forage less efficiently. Under stressful conditions (predation risks and presence of ungulates), lack of antipredatory cover around dehesa trees limited transportation of acorns, but also precluded mice activities outside tree canopies. As a result, post-dispersal predation rates were reduced and large acorns had a higher probability to survive. Our work shows that inter-specific interactions preventing efficient foraging by scatter-hoarders benefitted seed dispersal. Therefore, the maintenance of the full set of producers, consumers, dispersers and predators in ecosystems is key for promoting seed dispersal effectiveness in conditional mutualisms.

scholarly journals Cell Size Control and a Cell-intrinsic Maturation Program in Proliferating Oligodendrocyte Precursor Cells

1997 ◽  
Vol 138 (6) ◽  
pp. 1367-1377 ◽  
Author(s):  
Fen-Biao Gao ◽  
Martin Raff
Keyword(s):  
Cell Cycle ◽  
Cycle Time ◽  
Daughter Cell ◽  
Transition Probability ◽  
Video Recording ◽  
Precursor Cells ◽  
Oligodendrocyte Precursor Cells ◽  
Probability Models ◽  
Cell Cycle Time ◽  
Oligodendrocyte Precursor

We have used clonal analysis and time-lapse video recording to study the proliferative behavior of purified oligodendrocyte precursor cells isolated from the perinatal rat optic nerve growing in serum-free cultures. First, we show that the cell cycle time of precursor cells decreases with increasing concentrations of PDGF, the main mitogen for these cells, suggesting that PDGF levels may regulate the cell cycle time during development. Second, we show that precursor cells isolated from embryonic day 18 (E18) nerves differ from precursor cells isolated from postnatal day 7 (P7) or P14 nerves in a number of ways: they have a simpler morphology, and they divide faster and longer before they stop dividing and differentiate into postmitotic oligodendrocytes. Third, we show that purified E18 precursor cells proliferating in culture progressively change their properties to resemble postnatal cells, suggesting that progressive maturation is an intrinsic property of the precursors. Finally, we show that precursor cells, especially mature ones, sometimes divide unequally, such that one daughter cell is larger than the other; in each of these cases the larger daughter cell divides well before the smaller one, suggesting that the precursor cells, just like single-celled eucaryotes, have to reach a threshold size before they can divide. These and other findings raise the possibility that such stochastic unequal divisions, rather than the stochastic events occurring in G1 proposed by “transition probability” models, may explain the random variability of cell cycle times seen within clonal cell lines in culture.

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