scholarly journals Effect of tidal variation on the growth of Anadara senilis L. (1758) in the marine protected area of Bamboug (Senegal)

2020 ◽  
Vol 3 (3) ◽  
Keyword(s):  
Growth Rate ◽  
Sustainable Management ◽  
Marine Protected Area ◽  
Growth Parameters ◽  
Tidal Variation ◽  
R Software ◽  
Submerged Area ◽  
The Individual ◽  
A Minor

An in-situ study was conducted in the Sine Saloum Delta with the objective of studying the growth rate of Anadara senilis according to size and tide variation. The study revealed a minor allometry with values of 2.60 and 2.53 in the consistently submerged area and intermittently submerged area, respectively. The Von Bertalanffy linear growth parameters estimated from the ELEFAN in R Software are L∞ = 58.1 mm; K = 0.20, t0 = -0.70 and Φ’ = 2.83 in the intermittently submerged area and L∞ = 53.2 mm; K = 0.31; t0 = - 0.46 and Φ’= 2.94 in the consistently submerged area. The growth rate is inversely proportional to the size of the individual. The results of this study should help to develop strategies for the sustainable management of A. senilis in Sine Saloum Delta.

scholarly journals In situ Growth Rate Assessment of the Hexactinellid Sponge Asconema setubalense Using 3D Photogrammetric Reconstruction

2021 ◽  
Vol 8 ◽  
Author(s):  
Elena Prado ◽  
Javier Cristobo ◽  
Augusto Rodríguez-Basalo ◽  
Pilar Ríos ◽  
Cristina Rodríguez-Cabello ◽  
...  
Keyword(s):  
Growth Rate ◽  
Marine Protected Area ◽  
Growth Parameters ◽  
Benthic Communities ◽  
Monitoring Program ◽  
Maximum Size ◽  
Point Clouds ◽  
Von Bertalanffy ◽  
3D Point Clouds ◽  
Novel Approach

We describe the first application of a non-invasive and novel approach to estimate the growth rate of Asconema setubalense (Porifera, Hexactinellida) through the use of 3D photogrammetric methodology. Structure-from-Motion techniques (SfM) were applied to videos acquired with the Politolana ROTV in the El Cachucho Marine Protected Area (MPA) (Cantabrian Sea) on three different dates (2014, 2017, and 2019) over six years. With these data, a multi-temporal study was conducted within the framework of MPA monitoring. A complete 3D reconstruction of the deep-sea floor was achieved with Pix4D Mapper Pro software for each date. Having 3D point clouds of the study area enabled a series of measurements that were impossible to obtain in 2D images. In 3D space, the sizes (height, diameter, cup-perimeter, and cup-surface area) of several A. setubalense specimens were measured each year. The annual growth rates recorded ranged from zero (“no growth”) for a large size specimen, to an average of 2.2 cm year–1 in cup-diameter, and 2.5 cm year–1 in height for developing specimens. Von Bertalanffy growth parameters were estimated. Taking into account the size indicators used in this study and based on the von Bertalanffy growth model, this sponge reaches 95% maximum size at 98 years of age. During the MPA monitoring program, a high number of specimens disappeared. This raised suspicions of a phenomenon affecting the survival of this species in the area. This type of image-based methodology does not cause damage or alterations to benthic communities and should be employed in vulnerable ecosystem studies and MPA monitoring.

scholarly journals SOME ASPECTS OF THE CULTURE OF EUCHEMA

1970 ◽  
Vol 17 ◽  
pp. 145-146
Author(s):  
U. Horstman ◽  
A. Colina ◽  
W. Schramm
Keyword(s):  
Growth Rate ◽  
The Philippines ◽  
Minor Role ◽  
Bacterial Disease ◽  
Surrounding Water ◽  
Low Salinity ◽  
In Situ Experiments ◽  
Spraying Plants ◽  
A Minor

Eucheuma striatum and Eucheuma spinosum, are red algae of commercial value because of their carrageenin content, to an increasing extent are cultivated in the Philippines. The influence of environmental factors on growth rate and photosynthesis of these seaweeds were studied through observations in their natural biotope in seaweed farms, from in-situ experiments, and photosynthesis experiments in an incubator. While difference in light intensity and temperature play only a minor role, the algae were found out to be sensitive to low salinity and to the amount of dissolved gases and nutrients in the surrounding seawater. The algae can only be cultured in areas where there is sufficient current but to a cer-tain extent lack of current can be compensated by exposing the plants to wave action. This leads to certain conclusions regarding the most suitable method of commercial Eucheuma culture. Eucheuma can be successfully cultured in small rafts or in floating baskets in areas where there is insufficient current for the use of fixed nets or strings. There is evidence that-the CO2 -02 metabolism in the surrounding water plays an important role in Eucheuma growth. Eucheuma harvest can be further increased by introducing more nutrients. Fertilizing with phosphate caused a bigger increase in growth rate than with nitrogen. The method of spraying plants after temporarily removing them from the water, found to be more effective than fertilizing solutions by the use of clay pots. The presence of a bacterial disease, locally referred to as "ice-ice", was recognized as a clear indication that certain environment conditions were unfavourable for Eucheuma culture. Low salinity, in the first place, but also lack of current favors the attack of "ice-ice". Finally, it was found that Eucheuma adapts itself to its culture site in such a way that after maintaining seedlings in an area for a sufficient length of time, the cultured plants showed better growth rates and were resistent to unfavorable conditions than plants recently transferred to the area.

Estimating Bacterial Growth Parameters by Means of Detection Times

1999 ◽  
Vol 65 (2) ◽  
pp. 732-736 ◽  
Author(s):  
József Baranyi ◽  
Carmen Pin
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Bacterial Growth ◽  
Specific Growth ◽  
Growth Parameters ◽  
Physiological State ◽  
Cell Number ◽  
Maximum Specific Growth Rate ◽  
Specific Rate ◽  
The Individual

ABSTRACT We developed a new numerical method to estimate bacterial growth parameters by means of detection times generated by different initial counts. The observed detection times are subjected to a transformation involving the (unknown) maximum specific growth rate and the (known) ratios between the different inoculum sizes and the constant detectable level of counts. We present an analysis of variance (ANOVA) protocol based on a theoretical result according to which, if the specific rate used for the transformation is correct, the transformed values are scattered around the same mean irrespective of the original inoculum sizes. That mean, termed the physiological state of the inoculum,α̂, and the maximum specific growth rate, μ, can be estimated by minimizing the variance ratio of the ANOVA procedure. The lag time of the population can be calculated as λ = −ln α̂/μ; i.e. the lag is inversely proportional to the maximum specific growth rate and depends on the initial physiological state of the population. The more accurately the cell number at the detection level is known, the better the estimate for the variance of the lag times of the individual cells.

In-Situ Spectroscopic Ellipsometry for the Control of Si based Thin Multi-Layers Grown by UHV-CVD

1994 ◽  
Vol 342 ◽  
Author(s):  
F. Glowacki ◽  
A. Larre ◽  
F. Ferrieu ◽  
Y. Campidelli ◽  
D. Bensahel
Keyword(s):  
Growth Rate ◽  
Quantum Well ◽  
Spectroscopic Ellipsometry ◽  
Growth Parameters ◽  
Optical Data ◽  
Surface Control ◽  
Different Temperatures ◽  
Multi Quantum Well

ABSTRACTIn-situ Spectroscopic Ellipsometry as a function of time is used to follow the growth of Si/SiGe Multi Quantum Well (MQW) structures. It provides both the starting surface control and the growth parameters understanding (thickness, growth rate, Ge content). Si and SiGe optical data were recorded at different temperatures on individual Si and SiGe layers. Using the measured indices and the known thicknesses of the layers, the experimental MQW data are fitted without adjustable parameters.

Study of MBE ZnSe Growth Using Rheed Oscillations

1989 ◽  
Vol 145 ◽  
Author(s):  
Francoise S. Turco ◽  
M.C. Tamargo
Keyword(s):  
Growth Rate ◽  
Quantitative Study ◽  
Growth Parameters ◽  
Growth Conditions ◽  
High Energy ◽  
Growth Mechanisms ◽  
Mbe Growth ◽  
Wide Range ◽  
Main Growth

AbstractReflection high energy electron diffraction (RHEED) intensity oscillations are often used to investigate in situ the growth of III-V materials by molecular beam epitaxy (MBE). In this work, we have used RHEED oscillations to perform a quantitative study of the growth mechanisms of ZnSe, a II-VI semiconductor.Our experiments illustrate that the RHEED pattern of ZnSe is far less intense than that of III-V materials grown by MBE, and no specular spot is observed over a wide range of growth conditions. We have, however, been able to record up to 25 oscillations allowing a quantitative study of the growth of ZnSe by MBE. Thus we have used RHEED oscillations to make an in situ systematic study of the influence of the three main growth parameters (substrate temperature and Zn or Se impinging fluxes) on the ZnSe growth rate. We observed that the variation of the ZnSe growth rate is due to a non unity sticking coefficient of both Zn and Se species at the interface in the standard growth conditions used. Our observations can be described using a thermodynamic model and enable us to control the desired growth conditions. Our work demonstrates the utility of RHEED oscillations to understand the MBE growth mechanisms of II-VI compounds.

Epitaxial Growth on 4H-SiC on-Axis, 0.5°, 1.25°, 2°, 4°, 8° Off-Axis Substrates – Defects Analysis and Reduction

2011 ◽  
Vol 679-680 ◽  
pp. 95-98 ◽  
Author(s):  
Kinga Kościewicz ◽  
Wlodek Strupiński ◽  
Dominika Teklinska ◽  
Krystyna Mazur ◽  
Mateusz Tokarczyk ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Parameters ◽  
Elementary Cell ◽  
Epitaxial Layers ◽  
Developed Surface ◽  
Defects Analysis ◽  
Defect Elimination ◽  
Selection Of

A good selection of growth parameters (in-situ etching, C/Si ratio, growth rate) enables obtaining of ~1nm high steps of epitaxial layers, which are comparable to the size of an elementary cell (8°off-axis) and achieve the density of BPD=8•103/cm2. Due to crystallization on substrates with low misorientation (<2°off-axis) it is possible to obtain epitaxial layers substantially lacking in BPD dislocations. However, a slightly more developed surface with Ra=1-2.5nm (1.25°, 2°off-axis) characterizes these layers. By lowering the C/Si ratio, morphology of layers crystallized on substrates with low misorientation was improved. Extending growth rate improved both the crystallographic quality of the grown layers and their polytype stability. Nevertheless, growth without BPDs, also referred to as the homogeneous (4H) polytypic growth on 4H-SiC on-axis substrates, is the most efficient way of defect elimination.

Homoepitaxial growth of CVD diamond: effect of nitrogen contaminations on growth rates

1995 ◽  
Vol 416 ◽  
Author(s):  
C. Wild ◽  
R. Locher ◽  
P. Koidl
Keyword(s):  
Growth Rate ◽  
Microwave Plasma ◽  
Diamond Films ◽  
Polycrystalline Diamond ◽  
Laser Interferometry ◽  
Perfect Agreement ◽  
Homoepitaxial Growth ◽  
Process Gas ◽  
A Minor

ABSTRACTHomoepitaxial diamond films were deposited on {100} and {111} oriented substrates using microwave plasma assisted CVD. The growth rate was measured in situ using laser interferometry. Various amounts of 15N2 were admixed to the process gas (0-50 ppm). The growth rate on {100} faces was found to increase significantly (by a factor 1.8) with increasing 15N2 content. In contrast, on { 111 } faces only a minor increase of the growth rate upon nitrogen admixture was observed. These findings are in perfect agreement with the observed influence of nitrogen contaminations on the α-parameter, as derived by the X-ray texture analysis of polycrystalline diamond films [1]

The threshold energy for atom displacement in fcc metals

1990 ◽  
Vol 48 (4) ◽  
pp. 530-531
Author(s):  
Wilfried Sigle ◽  
Matthias Hohenstein ◽  
Alfred Seeger
Keyword(s):  
Growth Rate ◽  
Elevated Temperatures ◽  
Threshold Energy ◽  
Dislocation Loops ◽  
Absolute Minimum ◽  
Voltage Electron ◽  
Atom Displacement ◽  
Electron Microscopes ◽  
Fcc Metal

Prolonged electron irradiation of metals at elevated temperatures usually leads to the formation of large interstitial-type dislocation loops. The growth rate of the loops is proportional to the total cross-section for atom displacement,which is implicitly connected with the threshold energy for atom displacement, Ed . Thus, by measuring the growth rate as a function of the electron energy and the orientation of the specimen with respect to the electron beam, the anisotropy of Ed can be determined rather precisely. We have performed such experiments in situ in high-voltage electron microscopes on Ag and Au at 473K as a function of the orientation and on Au as a function of temperature at several fixed orientations.Whereas in Ag minima of Ed are found close to <100>,<110>, and <210> (13-18eV), (Fig.1) atom displacement in Au requires least energy along <100>(15-19eV) (Fig.2). Au is thus the first fcc metal in which the absolute minimum of the threshold energy has been established not to lie in or close to the <110> direction.

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