A hypothetical stochastic mechanism of radiation effects in single cells

1981 ◽  
Vol 213 (1191) ◽  
pp. 139-160 ◽  
Keyword(s):  
Stochastic Model ◽  
Radiation Damage ◽  
Radiation Effects ◽  
Primary Particle ◽  
Single Cells ◽  
Living Cells ◽  
The Other ◽  
Mathematical Treatment ◽  
Secondary Particles ◽  
Stochastic Mechanism

This paper is a sequel to an earlier one (Neyman & Puri 1976), which deals with a hypothetical structural stochastic model of radiation effects in living cells. This model incorporates two important details of the mechanism overlooked in its mathematical treatment by the previous workers. The first is that the passage of a single ‘primary’ radiation particle generates a ‘cluster’ of secondaries which can produce ‘hits’ that damage the living cells. The second detail concerns the time scales of radiation damage and of the subsequent repair. The events of arrival of a primary particle, its generation of secondary particles and their causing ‘hits’ on the sensitive targets within the cells, all occur for all practical purposes instantly. On the other hand the subsequent changes in the damaged cell, such as repair, appear to require measurable amounts of time. While the biological and physical justifications for some of the underlying assumptions of the model were discussed in the previous paper referred to above, the present paper is concerned mainly with the mathematical details and also with how the model attempts to explain some of the empirical findings available in the literature.

Mischkolonien auxotropher und Wildtypzellen nach Behandlung von Esdierichia coli-Zellen mit salpetriger Säure

1963 ◽  
Vol 18 (3) ◽  
pp. 245-252 ◽  
Author(s):  
F. Kaudewitz ◽  
K. Moebus ◽  
H. Kneser
Keyword(s):  
Experimental Evidence ◽  
Nitrous Acid ◽  
Single Cells ◽  
The Other ◽  
Mathematical Treatment ◽  
E Coli ◽  
Type 3 ◽  
Good Agreement ◽  
Hybrid Dna ◽  
In Cells

Cells of E. coli incubated in nitrous acid give rise 1. to unchanged wildtype colonies, 2. to colonies composed of wildtype and auxotrophic cells and 3. to colonies consisting of auxotrophic cells only. The mixed colonies are considered to originate from single cells each of them harbouring hybrid DNA with one subunit, probably a sisterstrand, changed by deamination of a cytosine or adenine, the other one with unchanged wildtype composition. In cells producing type 3 colonies this wildtype strand is mutated lethally by a separate deamination of a cytosine or adenine. A mathematical treatment of this hypothesis leads to predictions which are in good agreement with experimental evidence. The data obtained are used for an estimation of the number of gene-loci of E. coli.

The development of body and organ shape

BMC Zoology ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Ansa E. Cobham ◽  
Christen K. Mirth
Keyword(s):  
Relative Position ◽  
Body Shape ◽  
Single Cells ◽  
The Other ◽  
Geometric Features ◽  
Main Text ◽  
Size Characterization ◽  
Organ Shape ◽  
The Many

Abstract Background Organisms show an incredibly diverse array of body and organ shapes that are both unique to their taxon and important for adapting to their environment. Achieving these specific shapes involves coordinating the many processes that transform single cells into complex organs, and regulating their growth so that they can function within a fully-formed body. Main text Conceptually, body and organ shape can be separated in two categories, although in practice these categories need not be mutually exclusive. Body shape results from the extent to which organs, or parts of organs, grow relative to each other. The patterns of relative organ size are characterized using allometry. Organ shape, on the other hand, is defined as the geometric features of an organ’s component parts excluding its size. Characterization of organ shape is frequently described by the relative position of homologous features, known as landmarks, distributed throughout the organ. These descriptions fall into the domain of geometric morphometrics. Conclusion In this review, we discuss the methods of characterizing body and organ shape, the developmental programs thought to underlie each, highlight when and how the mechanisms regulating body and organ shape might overlap, and provide our perspective on future avenues of research.

On the mN, M Relation for Eastern North American Earthquakes

1987 ◽  
Vol 58 (4) ◽  
pp. 119-124 ◽  
Author(s):  
Gail M. Atkinson ◽  
David M. Boore
Keyword(s):  
North America ◽  
Stochastic Model ◽  
Ground Motion ◽  
Seismic Moment ◽  
The Other ◽  
Moment Magnitude ◽  
Scaling Relations ◽  
Eastern North America ◽  
Data Set ◽  
Meaningful Data

Abstract A stochastic model of ground motion has been used as a basis for comparison of data and theoretically-predicted relations between mN (commonly denoted by mbLg) and moment magnitude for eastern North America (ENA) earthquakes. mN magnitudes are recomputed for several historical ENA earthquakes, to ensure consistency of definition and provide a meaningful data set. We show that by itself the magnitude relation cannot be used as a discriminant between two specific spectral scaling relations, one with constant stress and the other with stress increasing with seismic moment, that have been proposed for ENA earthquakes.

A semi-hybrid model for malaria with limited superinfection

1998 ◽  
Vol 30 (04) ◽  
pp. 1027-1057 ◽  
Author(s):  
Philippe Picard
Keyword(s):  
Stochastic Model ◽  
Population Size ◽  
Hybrid Model ◽  
Human Population ◽  
Threshold Level ◽  
The Other ◽  
The Difference ◽  
The One

Modelling malaria with consistency necessitates the introduction of at least two families of interconnected processes. Even in a Markovian context the simplest fully stochastic model is intractable and is usually transformed into a hybrid model, by supposing that these two families are stochastically independent and linked only through two deterministic connections. A model closer to the fully stochastic model is presented here, where one of the two families is subordinated to the other and just a unique deterministic connection is required. For this model a threshold theorem can be proved but the threshold level is not the one obtained in a hybrid model. The difference disappears only when the human population size approaches infinity.

Neutron Radiation Effects on Lubricants and O-Rings for Target and Accelerator Applications

2021 ◽  
Vol 1024 ◽  
pp. 127-133
Author(s):  
Matteo Ferrari ◽  
Aldo Zenoni ◽  
Yong Joong Lee ◽  
Alberto Andrighetto
Keyword(s):  
Gamma Radiation ◽  
Radiation Damage ◽  
Radiation Effects ◽  
Nuclear Reactor ◽  
Neutron Radiation ◽  
Radioactive Isotopes ◽  
Structural Level ◽  
Radiation Resistant ◽  
Under Construction ◽  
Neutron Radiation Effects

Lubricants and O-rings are necessarily used for the construction of many accelerator-driven facilities as spallation sources or facilities for the production of radioactive isotopes. During operation, such component will absorb high doses of mixed neutron and gamma radiation, that can degrade their mechanical and structural properties. Experimental radiation damage tests of these components are mandatory for the construction of the facility. Methodologies for irradiation in nuclear reactor mixed fields and post-irradiation examination of lubricating oils, greases and O-rings were developed and are here presented. Samples were characterized with standard mechanical and physical-chemical tests. Parametric studies on the dose rate effects have been performed on O-rings. A case studies for a specific O-ring application in a gate valve has been developed. Some of the tested samples showed a dramatic change of their properties with dose, while others remain stable. Results were collected on nine commercial greases, on one oil and on four commercial elastomeric O-rings. The most radiation resistant among the selected products are now considered for application in facilities under construction. The main mechanisms of neutron and gamma radiation damage on these polymers were investigated at the mechanical and structural level.

scholarly journals Concerted loop motion triggers induced fit of FepA to ferric enterobactin

2014 ◽  
Vol 144 (1) ◽  
pp. 71-80 ◽  
Author(s):  
Chuck R. Smallwood ◽  
Lorne Jordan ◽  
Vy Trinh ◽  
Daniel W. Schuerch ◽  
Amparo Gala ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Exponential Decay ◽  
Living Cells ◽  
The Other ◽  
Iron Chelate ◽  
Spectroscopic Analyses ◽  
Conformational Motion ◽  
Surface Loops ◽  
Single Exponential ◽  
Loop Motion

Spectroscopic analyses of fluorophore-labeled Escherichia coli FepA described dynamic actions of its surface loops during binding and transport of ferric enterobactin (FeEnt). When FeEnt bound to fluoresceinated FepA, in living cells or outer membrane fragments, quenching of fluorophore emissions reflected conformational motion of the external vestibular loops. We reacted Cys sulfhydryls in seven surface loops (L2, L3, L4, L5, L7 L8, and L11) with fluorophore maleimides. The target residues had different accessibilities, and the labeled loops themselves showed variable extents of quenching and rates of motion during ligand binding. The vestibular loops closed around FeEnt in about a second, in the order L3 > L11 > L7 > L2 > L5 > L8 > L4. This sequence suggested that the loops bind the metal complex like the fingers of two hands closing on an object, by individually adsorbing to the iron chelate. Fluorescence from L3 followed a biphasic exponential decay as FeEnt bound, but fluorescence from all the other loops followed single exponential decay processes. After binding, the restoration of fluorescence intensity (from any of the labeled loops) mirrored cellular uptake that depleted FeEnt from solution. Fluorescence microscopic images also showed FeEnt transport, and demonstrated that ferric siderophore uptake uniformly occurs throughout outer membrane, including at the poles of the cells, despite the fact that TonB, its inner membrane transport partner, was not detectable at the poles.

scholarly journals Estimating primary energy of cosmic rays by calculating secondary particles density in optimum distance from shower core

2018 ◽  
Vol 27 (02) ◽  
pp. 1750190
Author(s):  
G. Rastegarzadeh ◽  
L. Rafezi
Keyword(s):  
Primary Particle ◽  
Primary Energy ◽  
Energy Estimation ◽  
Array Configuration ◽  
Secondary Particles ◽  
Shower Core ◽  
Optimum Distance ◽  
Array Detectors ◽  
Estimation Function ◽  
Minimum Uncertainty

Optimum distance (R[Formula: see text]) is a distance from the shower core in which the density calculated by lateral distribution function, has its minimum uncertainty. In this paper, using CORSIKA code, proton, carbon and iron primary in the energy range between 10[Formula: see text]–[Formula: see text][Formula: see text]eV are simulated to find R[Formula: see text] for Alborz-I array located at an altitude of 1200[Formula: see text]m above sea level. It is shown that R[Formula: see text] is approximately independent of characteristics of primary particle and it is only dependent to array configuration. Dependency of R[Formula: see text] on layout and detector spacing for 20 Alborz-I array detectors, are studied. It is shown that the Alborz-I array layout and its detector spacing result into the best (minimum uncertainty) R[Formula: see text] for its number of detectors. In this work, R[Formula: see text] for Alborz-I array is obtained about [Formula: see text][Formula: see text]m (from NKG function) and [Formula: see text][Formula: see text]m (from NKG type function). In addition, it is shown that, by finding dependency of primary energy to density in optimum distance, energy of primary particle can be estimated well. An energy estimation function is suggested and the function is examined by another set of simulated showers.

A Study of Radiation Effects in Curium-Doped Gd2Ti2O7 (Pyrochlore) and CaZrTi2O7 (Zirconolite)

1981 ◽  
Vol 11 ◽  
Author(s):  
J.W. Wald ◽  
P. Offemann
Keyword(s):  
Radiation Damage ◽  
Nuclear Waste ◽  
Radiation Effects ◽  
Laboratory Data ◽  
Primary Host ◽  
Waste Forms ◽  
Rare Earth Titanate ◽  
Effects Of Radiation ◽  
Similar Phase ◽  
Nuclear Waste Forms

Radiation effects studies in both glass and glass ceramic nuclear waste forms have identified a rare-earth titanate phase of the general formula (RE) 2Ti207 which is capable of acting as a host phase for actinides.1,2 Ringwood and co-workers3 have also proposed a structurally similar phase, zirconolite (CaZrTi2 07), as one of the primary host phases in the SYNROC waste form. Data from these and other previous studies, as well as mineralogical information available on these titanate phases, have not provided an unambiguous interpretation of the effects of radiation damage relative to nuclear waste forms. This paper reports new laboratory data concerning radiation damage effects in both of these phases.

The multiplicity characteristics of 7Li-Em interactions as a function of noninteracting projectile nucleons

2020 ◽  
Vol 29 (08) ◽  
pp. 2050063
Author(s):  
M. Mohery ◽  
E. M. Sultan ◽  
N. N. Abdallah ◽  
M. H. Farghaly
Keyword(s):  
Impact Parameter ◽  
Charged Particles ◽  
Heavy Ion ◽  
The Other ◽  
Total Charge ◽  
Secondary Particles ◽  
Ion Interactions ◽  
Charged Secondary ◽  
The Impact ◽  
Relativistic Particles

In this work, the interactions of 7Li nuclei with emulsion at 3 A GeV/c were studied. Multiplicity of the charged secondary particles as well as the charge of the outgoing projectile fragments were measured, while correlations among them are discussed. The values of the total charge of the noninteracting projectile nucleons and the average number of interacting projectile nucleons are estimated. The dependence of the secondary particles on the number of heavily-ionized tracks is analyzed. The results show that interactions of 7Li nuclei with emulsion nuclei exhibit a number of regularities, which had been noted in experiments with lighter nuclei. The absorption of relativistic particles, while increasing the degree of target destruction, is observed. The average multiplicities of the secondary charged particles depend on the impact parameter, as their values increase, while decreasing the impact parameter. The number of secondary charged particles in the heavy-ion interactions depends on the degree of disintegration of the target nuclei. This dependence is not observed in the case of the interaction of hadron with emulsion. The experimental data of the interaction of 7Li are systematically compared with the other interactions at different energies. The results agree with the corresponding results at nearly the same energy.

scholarly journals Simultaneous quantification of multiple endogenous biothiols in single living cells by plasmonic Raman probes

2017 ◽  
Vol 8 (11) ◽  
pp. 7582-7587 ◽  
Author(s):  
Shan-Shan Li ◽  
Qi-Yuan Guan ◽  
Mengmeng Zheng ◽  
Yu-Qi Wang ◽  
Deju Ye ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Single Cells ◽  
Principal Component ◽  
Component Analysis ◽  
Living Cells ◽  
Simultaneous Quantification ◽  
Single Living Cells ◽  
Single Living

Three endogenous biothiols in single cells were simultaneously quantified by plasmonic Raman probes and quantitative principal component analysis (qPCA).

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