scholarly journals Continuous color model as a tool to improve speleothem age model development

2021 ◽  
Vol 50 (3) ◽  
pp. 313-326
Author(s):  
Celia Campa-Bousoño ◽  
Ángel García-Pérez ◽  
Ana Moreno ◽  
Miguel Iglesias ◽  
Hai Cheng ◽  
...  
Keyword(s):  
Growth Rate ◽  
High Resolution ◽  
Environmental Variability ◽  
Model Development ◽  
Linear Interpolation ◽  
Large Sample Size ◽  
Continuous Growth ◽  
Age Model ◽  
Depth Relationship ◽  
Relationship Of

Because they can archive a variety of geochemical proxies and be precisely and accurately dated with the U-Th decay series chronometer, stalagmites are widely used for paleoclimate reconstructions. However, limitations in the use of this chronometer arise because U-Th dating is analytically time consuming, expensive, and requires a relatively large sample size. These limitations restrict the number of absolute dates usually obtained, which can result in significant uncertainties in the age model and inhibit the ability to archive high resolution records of environmental variability, particularly in those stalagmites where there are variations in growth rate not constrained by U-Th dates. Here, we explore the relationship between stalagmite color and growth rate. Consequently, we evaluate the use of a simple, practically non-destructive approach to model the age-depth relationship of stalagmites using the sample color to provide a continuous record of growth rate. The method was developed by comparing high-resolution color images with pre-determined U-Th dates along the growth axes of seven stalagmites. The obtained results suggest that prior to dating, a color-derived, continuous growth rate model may be used to identify important changes in growth rate which may aid in the determination of the most efficacious locations for U-Th dating. Further, continuous color-derived interpolations between U-Th derived dates may be superior to traditional linear interpolation methods. Such an approach has the potential to greatly improve a researcher’s ability to efficiently choose sampling locations for more precise, albeit laborious and costly, U-Th dating.

High-Resolution Measurements of Transient Changes in the Growth Rate of Intact Lupin Seedlings

1976 ◽  
Vol 3 (2) ◽  
pp. 237 ◽  
Author(s):  
DC Marshall ◽  
D Penny
Keyword(s):  
Growth Rate ◽  
Steady State ◽  
High Resolution ◽  
Simple Relationship ◽  
Anaerobic Conditions ◽  
High Co2 ◽  
Mannitol Solution ◽  
Condi Tions ◽  
Relationship Of ◽  
Minimum Yield

Measurements of the growth rate of intact lupin seedlings were made under steady-state conditions and as the environment was altered. Although the growth rate frequently changed smoothly with the new condition, there were several cases where periodicity or oscillations in the growth rate were observed. These cases included growth oscillations induced by: the solution in which the roots were immersed being changed back from a mannitol solution to water; the replacement of anaerobic conditions by air or oxygen; the tension being increased on the hypocotyl; and, under some condi- tions, the addition or removal of high CO2 concentrations. The observed periodicity is more complex than is accounted for by a simple relationship of the minimum yield stress increasing or decreasing with the growth rate, but more information is needed to develop a better model.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

TOWARD A HIGH-RESOLUTION AGE MODEL FOR THE DECCAN TRAPS BY U-PB ZIRCON GEOCHRONOLOGY

2017 ◽  
Author(s):  
Blair Schoene ◽  
◽  
Kyle Michael Samperton ◽  
Michael P. Eddy ◽  
Gerta Keller ◽  
...  
Keyword(s):  
High Resolution ◽  
Deccan Traps ◽  
Zircon Geochronology ◽  
Age Model

CONTINUOUS CULTURE OF BRUCELLA ABORTUS S.19

1961 ◽  
Vol 7 (4) ◽  
pp. 491-505 ◽  
Author(s):  
Andreas H. W. Hauschild ◽  
Hilliard Pivnick
Keyword(s):  
Growth Rate ◽  
Continuous Culture ◽  
Dilution Rate ◽  
Brucella Abortus ◽  
Specific Growth ◽  
Limiting Factor ◽  
Continuous Growth ◽  
Viable Cells ◽  
Metabolic Products ◽  
Growth Of Bacteria

An apparatus is described for the continuous growth of bacteria. Brucella abortus S.19 has been grown in continuous culture for periods up to 3 weeks with populations up to 2 × 1011viable cells per ml and without the establishment of nonsmooth variants.Concentrations between 3 × 109and 2 × 1011cells per ml could be maintained as a function of the dilution rate without the requirement of a known limiting factor in the medium. In a series of steady-state conditions, the specific growth rate increased steadily up to 0.28 hour−1with decreasing population levels.Incidence of mutants was governed by the dilution rate and could also be reduced by various chelating substances.In continuous growth combined with continuous dialysis, population levels were approximately twice those obtained in continuous growth without dialysis. The effect of dialysis appears to be the continuous removal of growth-limiting metabolic products.

scholarly journals Robustness of life histories to environmental variability in complex versus simple life cycles

2021 ◽  
Author(s):  
Annie Jonsson
Keyword(s):  
Growth Rate ◽  
Life Histories ◽  
Environmental Variability ◽  
Life Cycles ◽  
Relative Advantage ◽  
Complex Life Cycle ◽  
Life Stages ◽  
Vital Rates ◽  
Habitat Separation ◽  
Simple Life

AbstractMost animal species have a complex life cycle (CLC) with metamorphosis. It is thus of interest to examine possible benefits of such life histories. The prevailing view is that CLC represents an adaptation for genetic decoupling of juvenile and adult traits, thereby allowing life stages to respond independently to different selective forces. Here I propose an additional potential advantage of CLCs that is, decreased variance in population growth rate due to habitat separation of life stages. Habitat separation of pre- and post-metamorphic stages means that the stages will experience different regimes of environmental variability. This is in contrast to species with simple life cycles (SLC) whose life stages often occupy one and the same habitat. The correlation in the fluctuations of the vital rates of life stages is therefore likely to be weaker in complex than in simple life cycles. By a theoretical framework using an analytical approach, I have (1) derived the relative advantage, in terms of long-run growth rate, of CLC over SLC phenotypes for a broad spectrum of life histories, and (2) explored which life histories that benefit most by a CLC, that is avoid correlation in vital rates between life stages. The direction and magnitude of gain depended on life history type and fluctuating vital rate. One implication of our study is that species with CLCs should, on average, be more robust to increased environmental variability caused by global warming than species with SLCs.

scholarly journals High-resolution single-cell 3D-models of chromatin ensembles during Drosophila embryogenesis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Qiu Sun ◽  
Alan Perez-Rathke ◽  
Daniel M. Czajkowsky ◽  
Zhifeng Shao ◽  
Jie Liang
Keyword(s):  
High Resolution ◽  
Single Cell ◽  
3D Models ◽  
Computational Method ◽  
Midblastula Transition ◽  
Genome Wide ◽  
Large Ensembles ◽  
Chromatin Folding ◽  
Function Relationship ◽  
Relationship Of

AbstractSingle-cell chromatin studies provide insights into how chromatin structure relates to functions of individual cells. However, balancing high-resolution and genome wide-coverage remains challenging. We describe a computational method for the reconstruction of large 3D-ensembles of single-cell (sc) chromatin conformations from population Hi-C that we apply to study embryogenesis in Drosophila. With minimal assumptions of physical properties and without adjustable parameters, our method generates large ensembles of chromatin conformations via deep-sampling. Our method identifies specific interactions, which constitute 5–6% of Hi-C frequencies, but surprisingly are sufficient to drive chromatin folding, giving rise to the observed Hi-C patterns. Modeled sc-chromatins quantify chromatin heterogeneity, revealing significant changes during embryogenesis. Furthermore, >50% of modeled sc-chromatin maintain topologically associating domains (TADs) in early embryos, when no population TADs are perceptible. Domain boundaries become fixated during development, with strong preference at binding-sites of insulator-complexes upon the midblastula transition. Overall, high-resolution 3D-ensembles of sc-chromatin conformations enable further in-depth interpretation of population Hi-C, improving understanding of the structure-function relationship of genome organization.

scholarly journals Tumor growth characteristics of the Walker 256 AR tumor, a regressive variant of the rat Walker 256 A tumor

2010 ◽  
Vol 53 (5) ◽  
pp. 1101-1108 ◽  
Author(s):  
Fernando Guimarães ◽  
Alessandra Soares Schanoski ◽  
Tereza Cristina Samico Cavalcanti ◽  
Priscila Bianchi Juliano ◽  
Ana Neuza Viera-Matos ◽  
...  
Keyword(s):  
Growth Rate ◽  
Tumor Growth ◽  
Wistar Rats ◽  
Tumor Regression ◽  
Growth Characteristics ◽  
Tumor Growth Rate ◽  
Continuous Growth ◽  
Tumor Bearing ◽  
Walker 256 ◽  
Complete Tumor

The present study aimed at characterizing the subcutaneous development of the Walker 256 (W256) AR tumor, a regressive variant of the rat W256 A tumor. Wistar rats were injected subcutaneously with 4x10(6) W256 A or W256 AR tumor cells. The development of tumors was evaluated daily by percutaneous measurements. None of the W256 A tumors (n=20) regressed, but 62% of the W256 AR tumor-bearing rats (n=21) underwent complete tumor regression within 35 days. Continuous growth of AR tumors was characterized by an increase of the tumor growth rate from day 12, which reached values above 1.0 g/day, and were significantly higher (p<0.05) than those of the regressive AR tumors. Immunosuppression by irradiation before subcutaneous injection of AR cells completely abrogated tumor regression and was associated with severe metastatic dissemination. Daily evaluation of the tumor growth rate enabled the discrimination, in advance, between continuously growing tumors and those that regressed later on.

scholarly journals Title: IDENTIFYING THE AXILLARY NERVE DURING SHOULDER SURGERY: AN ANATOMIC STUDY USING ADVANCED IMAGING

2021 ◽  
Vol 9 (7_suppl3) ◽  
pp. 2325967121S0003
Author(s):  
Michael E. Hachadorian ◽  
Brendon C. Mitchell ◽  
Matthew Y. Siow ◽  
Wilbur Wang ◽  
Tracey Bastrom ◽  
...  
Keyword(s):  
High Resolution ◽  
Rotator Cuff ◽  
Axillary Nerve ◽  
Small Sample ◽  
Shoulder Surgery ◽  
Rotator Cuff Tears ◽  
Large Sample Size ◽  
Musculoskeletal Radiology ◽  
Reconstructive Procedures ◽  
Mri Studies

Background: The axillary nerve (AXN) is one of the more commonly injured nerves during shoulder surgery. Prior anatomic studies of the AXN in adults were performed using cadaveric specimens with small sample sizes. Our research observes a larger cohort of magnetic resonance imaging (MRI) studies in order to gain a more representative sample of the course of the axillary nerve and aid surgeons intraoperatively. Methods: High-resolution 3T MRI studies performed at our institution from January 2010 to June 2019 were reviewed. Four blinded reviewers with musculoskeletal radiology or orthopaedic surgery training measured the distance of the AXN to the surgical neck of the humerus (SNH), the lateral tip of the acromion (LTA), and the inferior glenoid rim (IGR). Intra-class Correlation Coefficient (ICC) was calculated to assess reliability between reviewers. The nerve location was assessed relative to rotator cuff tear status. Results: A total of 257 shoulder MRIs were included. ICC was excellent at 0.80 for SNH, 0.90 for LTA and 0.94 for IGR. All intra-observer reliabilities were above 0.80. Mean distance from AXN to SNH was 1.7 cm (0.7-3.1 cm, IQR 1.38-2.00) and AXN to IGR was 1.6 cm (0.6-2.6 cm, IQR 1.33-1.88). The mean AXN to LTA distance was 7.1 cm, with a range of 5.2 to 9.0 cm across patient heights; there was a large effect size related to LTA to AXN distance and patient height with a correlation of r=0.603, (p<0.001). Rotator cuff pathology appears to affect nerve location by increasing the distance between AXN and SNH (p = 0.027). Discussion/Conclusion: The AXN is vulnerable to injury during both open and arthroscopic shoulder procedures. This injury can be either a result of direct trauma to the nerve or secondary to traction placed on the nerve with reconstructive procedures that distalize the humerus. Our study demonstrates that the axillary nerve can be found as little as 5.6 mm from IGR and 6.9 mm from the SNH. Additionally, we illustrate the relationship between patient height and LTA to AXN distance and complete rotator cuff tears and SNH to AXN distance. Our study is the first to demonstrate the nerve’s proximity to important surgical landmarks of the shoulder using a large sample size of high-resolution images in living human shoulders. Tables/Figures: [Figure: see text][Table: see text]

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