Minimum achievable decay rates of the discrete linear inclusion

2015 ◽  
Author(s):  
Ray Essick ◽  
Geir Dullerud
Keyword(s):  
Decay Rates ◽  
Linear Inclusion

Comparison of decay rates of faecal indicator organisms in recreational coastal water and sediment

2002 ◽  
Vol 2 (3) ◽  
pp. 131-138 ◽  
Author(s):  
D.L. Craig ◽  
H.J. Fallowfield ◽  
N.J. Cromar
Keyword(s):  
Water Column ◽  
Coastal Water ◽  
Decay Rates ◽  
Organic Carbon Content ◽  
Indicator Organisms ◽  
Filtration Method ◽  
E Coli ◽  
Water And Sediment ◽  
Increased Risk ◽  
High Organic Carbon Content

A laboratory based microcosm study utilising intact non-sterile sediment cores was undertaken to determine the survival of the faecal indicator organisms Escherichia coli, Enterococcus faecium and somatic coliphage in both recreational coastal water and sediment. Overlying water was inoculated with the test organisms and incubated at 10°C, 20°C or 30°C. E. coli, enterococcus and coliphage were enumerated from the water column and sediment by the membrane filtration method, Enterolert (IDEXX Laboratories) and the double-agar overlay methods respectively on days 0, 1, 2, 7, 14 and 28 following inoculation. It was demonstrated that for all organisms, greater decay (k; d-1) occurred in the water column compared to sediment. Sediment characteristics were found to influence decay, with lowest decay rates observed in sediment consisting of high organic carbon content and small particle size. Decay of E. coli was significantly greater in both the water column and sediment compared with enterococcus and coliphage under all conditions. Decay of enterococcus was found to closely resemble that of coliphage decay. Survival of all organisms was inversely related to temperature, with greatest decay at 30°C. However, increased temperature had a less significant impact on survival of enterococcus and coliphage compared with E. coli. The importance of this study for estimating risk from recreational exposure is great if some pathogenic microorganisms behave similarly to the organisms tested in this study. In particular if survival rates of pathogens are similar to enterococcus and coliphage, then their ability to accumulate in coastal sediment may lead to an increased risk of exposure if these organisms are resuspended into the water column due to natural turbulence or human recreational activity.

scholarly journals A new stability result for a thermoelastic Bresse system with viscoelastic damping

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Soh Edwin Mukiawa ◽  
Cyril Dennis Enyi ◽  
Tijani Abdulaziz Apalara
Keyword(s):  
Stability Result ◽  
Bending Moment ◽  
Decay Rates ◽  
Viscoelastic Damping ◽  
Physical Parameters ◽  
Bresse System ◽  
Solution Energy ◽  
Optimal Decay Rates ◽  
Optimal Decay ◽  
Weaker Conditions

AbstractWe investigate a thermoelastic Bresse system with viscoelastic damping acting on the shear force and heat conduction acting on the bending moment. We show that with weaker conditions on the relaxation function and physical parameters, the solution energy has general and optimal decay rates. Some examples are given to illustrate the findings.

scholarly journals Longitudinal analysis of antibody decay in convalescent COVID-19 patients

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Weiming Xia ◽  
Mingfei Li ◽  
Ying Wang ◽  
Lewis E. Kazis ◽  
Kim Berlo ◽  
...  
Keyword(s):  
Immune Response ◽  
Reduction Rate ◽  
Mixed Linear Model ◽  
Decay Rates ◽  
Primary Study ◽  
Igg Antibody ◽  
Blood Samples ◽  
Response Capacity ◽  
Index Level ◽  
Abbott Architect

AbstractDetermining the sustainability of antibodies targeting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is essential for predicting immune response against the Coronavirus disease 2019 (COVID-19). To quantify the antibody decay rates among the varying levels of anti-nucleocapsid (anti-N) Immunoglobulin G (IgG) in convalescent COVID-19 patients and estimate the length of time they maintained SARS-CoV-2 specific antibodies, we have collected longitudinal blood samples from 943 patients over the course of seven months after their initial detection of SARS-CoV-2 virus by RT-PCR. Anti-N IgG levels were then quantified in these blood samples. The primary study outcome was the comparison of antibody decay rates from convalescent patients with high or low initial levels of antibodies using a mixed linear model. Additional measures include the length of time that patients maintain sustainable levels of anti-N IgG. Antibody quantification of blood samples donated by the same subject multiple times shows a gradual decrease of IgG levels to the cutoff index level of 1.4 signal/cut-off (S/C) on the Abbott Architect SARS-CoV-2 IgG test. In addition, this study shows that antibody reduction rate is dependent on initial IgG levels, and patients with initial IgG levels above 3 S/C show a significant 1.68-fold faster reduction rate compared to those with initial IgG levels below 3 S/C. For a majority of the donors naturally occurring anti-N antibodies were detected above the threshold for only four months after infection with SARS-CoV-2. This study is clinically important for the prediction of immune response capacity in COVID-19 patients.

scholarly journals Influence of Tsunami Aspect Ratio on Near and Far-Field Tsunami Amplitude

Geosciences ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 178
Author(s):  
Natalia K. Sannikova ◽  
Harvey Segur ◽  
Diego Arcas
Keyword(s):  
Aspect Ratio ◽  
Near Field ◽  
Decay Rates ◽  
Far Field ◽  
Present Evidence ◽  
Positive Wave ◽  
Initial Wave ◽  
N Wave ◽  
Tsunami Amplitude ◽  
Wave Shapes

This study presents a numerical investigation of the source aspect ratio (AR) influence on tsunami decay characteristics with an emphasis in near and far-field differences for two initial wave shapes Pure Positive Wave and N-wave. It is shown that, when initial total energy for both tsunami types is kept the same, short-rupture tsunami with more concentrated energy are likely to be more destructive in the near-field, whereas long rupture tsunami are more dangerous in the far-field. The more elongated the source is, the stronger the directivity and the slower the amplitude decays in the intermediate- and far-fields. We present evidence of this behavior by comparing amplitude decay rates from idealized sources and showing their correlation with that observed in recent historical events of similar AR.

Proton inelastic scattering in inverse kinematics as a mean for determining decay rates in continuum: The 9Be + p case

2021 ◽  
Vol 1008 ◽  
pp. 122155
Author(s):  
A. Pakou ◽  
O. Sgouros ◽  
V. Soukeras ◽  
F. Cappuzzello ◽  
L. Acosta ◽  
...  
Keyword(s):  
Inelastic Scattering ◽  
Inverse Kinematics ◽  
Decay Rates ◽  
Proton Inelastic Scattering

Stabilization of the wave equation with a nonlinear delay term in the boundary conditions

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Wassila Ghecham ◽  
Salah-Eddine Rebiai ◽  
Fatima Zohra Sidiali
Keyword(s):  
Wave Equation ◽  
Original Problem ◽  
Existence Of Solutions ◽  
Semigroup Theory ◽  
Decay Rates ◽  
Uniform Decay ◽  
Delay Term ◽  
Nonlinear Semigroup Theory ◽  
Nonlinear Boundary Feedback ◽  
Nonlinear Delay

Abstract A wave equation in a bounded and smooth domain of ℝ n {\mathbb{R}^{n}} with a delay term in the nonlinear boundary feedback is considered. Under suitable assumptions, global existence and uniform decay rates for the solutions are established. The proof of existence of solutions relies on a construction of suitable approximating problems for which the existence of the unique solution will be established using nonlinear semigroup theory and then passage to the limit gives the existence of solutions to the original problem. The uniform decay rates for the solutions are obtained by proving certain integral inequalities for the energy function and by establishing a comparison theorem which relates the asymptotic behavior of the energy and of the solutions to an appropriate dissipative ordinary differential equation.

scholarly journals Parameter-dependent transmission dynamics and optimal control of foot and mouth disease in a contaminated environment

2019 ◽  
Vol 27 (1) ◽  
Author(s):  
Francis Mugabi ◽  
Joseph Mugisha ◽  
Betty Nannyonga ◽  
Henry Kasumba ◽  
Margaret Tusiime
Keyword(s):  
Optimal Control ◽  
Deterministic Model ◽  
Foot And Mouth Disease ◽  
Decay Rates ◽  
Mouth Disease ◽  
Control Measures ◽  
Transmission Dynamics ◽  
Optimality System ◽  
Foot And Mouth ◽  
Environmental Decontamination

AbstractThe problem of foot and mouth disease (FMD) is of serious concern to the livestock sector in most nations, especially in developing countries. This paper presents the formulation and analysis of a deterministic model for the transmission dynamics of FMD through a contaminated environment. It is shown that the key parameters that drive the transmission of FMD in a contaminated environment are the shedding, transmission, and decay rates of the virus. Using numerical results, it is depicted that the host-to-host route is more severe than the environmental-to-host route. The model is then transformed into an optimal control problem. Using the Pontryagin’s Maximum Principle, the optimality system is determined. Utilizing a gradient type algorithm with projection, the optimality system is solved for three control strategies: optimal use of vaccination, environmental decontamination, and a combination of vaccination and environmental decontamination. Results show that a combination of vaccination and environmental decontamination is the most optimal strategy. These results indicate that if vaccination and environmental decontamination are used optimally during an outbreak, then FMD transmission can be controlled. Future studies focusing on the control measures for the transmission of FMD in a contaminated environment should aim at reducing the transmission and the shedding rates, while increasing the decay rate.

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