scholarly journals Skeletochronology and Paleohistology of Hyposaurus rogersii (Crocodyliformes, Dyrosauridae) from the Early Paleogene of New Jersey, USA

Animals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3067
Author(s):  
Rodrigo A. Pellegrini ◽  
Wayne R. Callahan ◽  
Alexander K. Hastings ◽  
David C. Parris ◽  
John D. McCauley
Keyword(s):  
Cross Sections ◽  
Fundamental System ◽  
Small Sample ◽  
Medullary Cavity ◽  
Mature Adult ◽  
Linear Path ◽  
Near Shore ◽  
Cyclical Growth ◽  
Early Paleogene ◽  
Secondary Osteons

The paleohistology of dyrosaurids is known from a small sample, despite being common fossils and representing a rare lineage of crocodylomorphs that survived the Cretaceous–Paleogene extinction. Their lifestyle has been inferred only from sections of the snout, vertebrae, partial femur, and tibia. To improve this, we conducted a skeletochronological and paleohistological study of midshaft cross-sections of both femora and humeri of a nearly complete Hyposaurus rogersii skeleton. We found lamellar-zonal bone that underwent remodeling, evidenced by resorption cavities and abundant secondary osteons within the primary periosteal cortex. The osteons, mostly longitudinally oriented and arranged in circular rows, often anastomose radially along a linear path, resembling radial rows. The medullary cavity is completely open, lacking trabeculae: endosteal deposition is limited to thin lamellae surrounding the cavity. Analysis of cyclical growth marks and the presence of an external fundamental system indicate the specimen was a fully mature adult 17–18 years of age. Comparison of the skeleton to others suggests sexual dimorphism and that it was female. The open medullary cavity, and no evidence for pachyosteosclerosis, osteosclerosis, osteoporosis, or pachyostosis indicate H. rogersii was not a deep diver or a fast swimmer in the open ocean but a near-shore marine ambush predator.

scholarly journals Application of the EGPT methodology in the analysis of small-sample reactivity worth experiments

2018 ◽  
Vol 4 ◽  
pp. 44 ◽  
Author(s):  
Pierre Leconte ◽  
Jean Tommasi ◽  
Alain Santamarina ◽  
Patrick Blaise ◽  
Paul Ros
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Capture Cross Section ◽  
Reference Sample ◽  
Small Sample ◽  
Capture Cross ◽  
Theoretical Formulation ◽  
Sensitivity Coefficients ◽  
Spectrum Experiment ◽  
The Impact

In the current paper, we investigate the application of the Equivalent Generalized Perturbation Theory (EGPT) to derive trends and associated covariances on the neutron capture cross section of one major fission product for both light water reactors and sodium-cooled fast reactors which is Rhodium-103. To do so, we have considered the ERMINE-V/ZONA1 & ZONA3 fast spectrum experiment and the MAESTRO thermal-spectrum experiment, where samples of these materials were oscillated in the MINERVE facility. In the paper, the theoretical formulation of EPGT is described and its derivation in the special case of the close loop oscillation technique where the reactivity worth is determined thanks to a power control system. A numerical benchmark is presented to assess the relevance of sensitivity coefficients provided by EGPT against direct perturbations where the microscopic cross sections are manually changed before calculating the adjoint and forward flux. The breakdown between direct and indirect contributions in the sensitivity analysis of the sample reactivity worth is presented and discussed, with the impact of using a calibration reference sample to normalize the measured reactivity worth. Finally, the assimilation of integral trends is done with the CONRAD code, using C/E comparisons between TRIPOLI4/JEFF3.2 calculations and experimental results and the sensitivity coefficients provided by the EGPT. Preliminary results of this study are showing that the JEFF3.2 evaluation of 103Rh gives satisfactory agreements in both thermal and fast spectrum experiments and that the combination of them can lead to a significant uncertainty reduction on the capture cross section, from ±5% to ±3% in the resolved resonance range (1 eV–10 keV) and from ±8% to ±5% in the unresolved resonance range (10 keV–1 MeV).

scholarly journals Time-restricted feeding from adulthood to old age improves biconditional associative learning in geriatric rats regardless of macronutrient composition

2020 ◽  
Author(s):  
Abbi R. Hernandez ◽  
Quinten P. Federico ◽  
Sara N. Burke
Keyword(s):  
Dietary Intervention ◽  
Small Sample Size ◽  
Control Diet ◽  
Small Sample ◽  
Restricted Feeding ◽  
Macronutrient Composition ◽  
Mature Adult ◽  
Age Related ◽  
Feeding Regimen ◽  
Ad Libitum

AbstractDeclining health and cognition are hallmarks of advanced age that reduce both the quality and length of the lifespan. While caloric restriction has been highlighted as a dietary intervention capable of improving the healthspan by restoring metabolic function in late life, time-restricted feeding and changes in dietary macronutrient composition may be more feasible alternatives with similar health outcomes. To investigate the potential of these two interventions, a pilot cohort of fully mature adult rats were placed on a time-restricted feeding regimen of a ketogenic or micronutrient and calorically matched control diet from 8 to 21 months of age. A third group of rats was permitted to eat standard chow ad libitum. At 22 months, all rats were then placed on time-restricted feeding and tested on a biconditional association task. While the data presented here are preliminary (small sample size of 3-4/diet group), additional animals are currently undergoing the feeding regimen, and will be added into the behavioral studies at a later date. For the current data, regardless of dietary composition, time-restricted-fed rats performed significantly better than ad libitum-fed rats. This observation could not be accounted for by differences in motivation, procedural or sensorimotor impairments, indicating that mid-life dietary interventions capable of preventing metabolic impairments may also serve to prevent age-related cognitive decline.

scholarly journals A classical approach to eigenvalue problems associated with a pair of mixed regular Sturm-Liouville equations I

2001 ◽  
Vol 14 (2) ◽  
pp. 205-214 ◽  
Author(s):  
M. Venkatesulu ◽  
Pallav Kumar Baruah
Keyword(s):  
Boundary Value Problems ◽  
Cross Sections ◽  
Eigenvalue Problems ◽  
Fundamental System ◽  
Variable Cross ◽  
Classical Approach ◽  
New Class ◽  
Transverse Vibrations ◽  
Acoustic Waveguides ◽  
Sturm Liouville

In the studies of acoustic waveguides in ocean, buckling of columns with variable cross sections in applied elasticity, transverse vibrations in non homogeneous strings, etc., we encounter a new class of problems of the type L1y1=−d2y1dx2+q1(x)y1=λy1 defined on an interval [d1,d2] and L2y2=−d2y2dx2+q2(x)y2=λy2 on the adjacent interval [d2,d3] satisfying certain matching conditions at the interface point x=d2.Here in Part I, we constructed a fundamental system for (L1,L2) and derive certain estimates for the same. Later, in Part II, we shall consider four types of boundary value problems associated with (L1,L2) and study the corresponding spectra.

scholarly journals Age-related changes of the histological structure in the limb bones of the domestic fowl

2021 ◽  
Vol 22 (2) ◽  
pp. 264-277
Author(s):  
N. S. Sukhanova
Keyword(s):  
Bone Tissue ◽  
Cross Sections ◽  
Domestic Fowl ◽  
Distal Part ◽  
Histological Structure ◽  
Limb Bones ◽  
Tissue Degeneration ◽  
Age Related ◽  
The Cross ◽  
Secondary Osteons

To assess the possibility of using the bird bone tissue as a recording structure, the histomorphological parameters of the bone tissue of laying hens of the lohman brown cross from the Kirov region (9 females and 1 male) aged from 1 month to 7.5 years were investigated. The comparison of the cross-sections of the humerus and femur, the phalanx of the toe and tibiotarsus of a 6-year-old individual revealed that tibiotarsus is the least susceptible to resorption. For further research in 7 individuals, this bone was divided into 3 sections (T1, T2 and T3), for each of which the description and measurement of the microstructure of the cross sections was carried out. It was revealed that the process of resorption of the periosteum begins at 2.5 years of age with the appearance of primary osteons. At the age of 3.5 years and later they penetrate into all layers of the periosteum, locating in chains between the lines of arrested growth. At 4.5 years of age, secondary osteons appear in the place of the primary ones, and areas of resorption are formed at the intersection of the Haversian and Volkmann canals. At the age of 5.5 years the medullary bone disappears from the bone cavity, rounded cavities filled with centripetal deposition of new bone tissue at the edges appear within the resorption sites. At the age of 6-7 years, bone tissue degeneration occurs, when the small cavities enlarge and merge into large resorption cavities, up to the complete resorption of the mesost. In the distal part of tibiotarsus (T3), a prolonged apposition of the layers of the periosteum and the latest resorption were recorded. The increase of the thickness of the periosteum and a decrease in the density of the osteon population was revealed by the morphometry of cross sections of the center of diaphysis. The sites of tibiotarsus where the age of females corresponds to the lines of growth layer of the periosteum were determined. The sites with additional lines of the arrested growth were demarcated. It was concluded that the periosteal layer of the domestic fowl tibiotarsus in the distal and proximal sites are suitable as a recording structure.

Monte Carlo comparison of LCCA- and ML-based cointegration tests for panel var process with cross-sectional cointegrating vectors

2019 ◽  
Vol 65 (2) ◽  
pp. 173-182
Author(s):  
Piotr Kębłowski
Keyword(s):  
Cross Sections ◽  
Small Sample ◽  
Small Samples ◽  
Panel Var ◽  
Var Models ◽  
Rank Tests ◽  
Cross Sectional ◽  
Long Run ◽  
Cointegration Tests ◽  
Small Sample Properties

Small-sample properties of bootstrap cointegration rank tests for unrestricted panel VAR process are considered when long-run cross-sectional dependencies occur. It is shown that the bootstrap cointegration rank tests for the panel VAR model based on levels canonical correlation analysis are oversized, whereas the bootstrap cointegration rank tests based on maximum likelihood framework are undersized. Moreover, the former tests are in general outperformed by the latter in terms of performance. The results of the investigation indicate that the ML-based bootstrap cointegration rank tests perform well in small samples for small-sized panel VAR models with a few cross-sections.

scholarly journals A classical approach to eigenvalue problems associated with a pair of mixed regular Sturm-Liouville equations I

2000 ◽  
Vol 13 (3) ◽  
pp. 303-312
Author(s):  
M. Venkatesulu ◽  
Pallav Kumar Baruah
Keyword(s):  
Boundary Value Problems ◽  
Cross Sections ◽  
Eigenvalue Problems ◽  
Fundamental System ◽  
Variable Cross ◽  
Classical Approach ◽  
New Class ◽  
Transverse Vibrations ◽  
Acoustic Waveguides ◽  
Sturm Liouville

In the studies of acoustic waveguides in ocean, buckling of columns with variable cross sections in applied elasticity, transverse vibrations in non-homogeneous strings, etc., we encounter a new class of problems of the type L1y1=−d2y1dx2+q1(x)y1=λy1 defined on an interval [d1,d2] and L2y2=−d2y2dx2+q2(x)y2=λy2 on the adjacent interval [d2,d3] satisfying certain matching conditions at the interface point x=d2.Here in Part I, we constructed a fundamental system for (L1,L2) and derive certain estimates for the same. Later, in Part II, we shall consider four types of boundary value problems associated with (L1,L2) and study the corresponding spectra.

scholarly journals Osteohistology of the hadrosauroid (Dinosauria: Ornithopoda) from Labirinta cave, Bulgaria: An example of insular dwarfism or simply young giant?

2018 ◽  
Author(s):  
Vladimir Georgiev Nikolov
Keyword(s):  
Bone Tissue ◽  
Bone Remodeling ◽  
Growth Rates ◽  
Fundamental System ◽  
Lamellar Bone ◽  
Mature Animal ◽  
Thin Sections ◽  
Tissue Matrix ◽  
Secondary Osteons ◽  
Upper Maastrichtian

The hadrosauroid remains from Kajlâka Formation (Upper Maastrichtian) limestones of the Labirinta Cave, NW Bulgaria, are most interesting for their small size but without paleohistological data it was not possible to affirm whether they belong to young individual/s or to small-sized mature animal/s. To elucidate their histology and ontogenetic state, 6 associated cortical fragments and one partial diaphysis were sectioned and studied. Thin-sections reveal cortex build of highly vascularized tissues of the woven-parallel complex. Vascularization patterns are somewhat intermediate between those of derived hadrosauroids and non-hadrosauroid ornithopods, yet characterized by thick sequences of laminar bone. Bone tissue matrix consists largely of parallel-fibered or lamellar bone tissue. Cortical tissues are affected by processes of secondary remodeling that locally results in dense Haversian tissue reaching the subperiosteal cortex. No growth marks or external fundamental system are observed in any of the specimens. The transition from bone tissues with predominantly longitudinally oriented osteons to true laminar bone, the thickness of the latter, the extensive secondary bone remodeling and Haversian tissue with at least 3 generations of secondary osteons, as well as the presence of endosteal bone in one of studied specimens all suggest that the material pertains to animal/s at a late sub-adult ontogenetic stage. The high presence of parallel-fibered and lamellar tissues in the cortex indicates significantly slower growth rates in comparison with similarly sized but ontogenetically younger derived hadrosauroids. The osteohistology of the Bulgarian hadrosauroid reveals yet another example of dinosaurian insular dwarfism in latest Cretaceous European archipelago.

scholarly journals A classical approach to eigenvalue problems associated with a pair of mixed regular Sturm-Liouville equations II

2002 ◽  
Vol 15 (2) ◽  
pp. 181-187
Author(s):  
M. Venkatesulu ◽  
Pallav Kumar Baruah
Keyword(s):  
Boundary Value Problems ◽  
Cross Sections ◽  
Eigenvalue Problems ◽  
Fundamental System ◽  
Variable Cross ◽  
Classical Approach ◽  
New Class ◽  
Transverse Vibrations ◽  
Acoustic Waveguides ◽  
Sturm Liouville

In the studies of acoustic waveguides in ocean, buckling of columns with variable cross sections in applied elasticity, transverse vibrations in nonhomogeneous strings, etc., we encounter a new class of problems of the type L1y1≡−y1′​′+q1(x)y1=λy1 defined on an interval [d1,d2] and L2y2≡−y2′​′+q2(x)y2=λy2 defined on the interval [d2,d3] satisfying certain matching conditions at the interface point x=d2.Earlier, in Part I, we constructed a fundamental system for (L1,L2) and derived certain estimates for the same.Here, in Part II, we consider four types of boundary value problems associated with (L1,L2) and study the corresponding spectra.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

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