Constant Growth Rate Research Articles

The impact of swirl and wake strength on turbulent axisymmetric wake evolution

An experimental investigation of swirl and wake strength influence on axisymmetric turbulent wake evolution was conducted. A novel wake generator design wire mounted in a wind tunnel test section with low free-stream turbulence produced wake Reynolds numbers based on momentum thickness and free-stream velocity in excess of 14 000 and swirl numbers up to 0.4 with minimal blockage. Steady-state blade element momentum simulations of reference wind turbine designs indicated that wind turbines operate in the flow regimes studied, indicating the practical aspects of this work. Stereoscopic particle image velocimetry was used to acquire three components of velocity in the swirling wake at locations up to approximately ten diameters downstream. Quantitative measures of wake growth and decay were deduced using available equilibrium similarity scaling for the swirling wake. The results show an increase above 50% in growth and axial velocity decay rate constants over the range of swirl strength studied compared to those of the non-swirling wake. Tangential velocity decay constants were shown to decrease with swirl strength over the range of conditions studied. Notably, changes in wake strength have little influence on growth and decay rates when compared to changes in swirl strength for the flow regimes studied in this work.

Phenotypic effect of growth media on Arabidopsis thaliana root hair growth

ABSTRACT Over the years, many different growth media have been used to grow Arabidopsis thaliana in vitro in petri dishes. For these media the nutrient composition may vary, sugars may or may not be added, the medium may or may not be buffered and there is a choice between different gelling agents. The magnitude of possible combinations of these variables obstructs easy comparison of seedling phenotypes grown on the different media. This is especially obvious when it concerns the study of root hairs that are extremely sensitive to changes in their environment. To demonstrate this effect, we have grown Arabidopsis thaliana wild-type seeds on 18 different combinations of growth media and quantified root hair development. Comparison of root hair length and the respective root hair profiles identified the media that result in the formation of the longest root hairs. On these favored media they elongate through tip growth at a constant growth rate until they reach their final length (around 0.6 mm) at a distance of ±4 mm from the root tip.

High-temperature effects on kinetics and grain orientation of the Cu41Sn11 phase formed from the full Cu3Sn joint during the aging process

In the present study, the intermetallic compound (IMC) joints consisting of Cu3Sn were aged at high temperatures of 540, 560, and 580 °C to form a sole phase of Cu41Sn11 in a short time period. The variations in morphology, growth kinetics, and grain orientation for the Cu41Sn11 phase originating from the Cu3Sn during the high temperature conditions were systematically investigated. The original Cu3Sn phase appeared as slender grains, while the final phase, which contained Cu41Sn11 grains, was displayed as coarse columnar grains. The growth kinetics for the Cu41Sn11 phase during the 540, 560, and 580 °C temperature testing periods were roughly controlled by the grain boundary diffusion and more precisely controlled by the activation energy, which was 72.86 kJ/mol. The growth rate constant of k0 was 2.5*10^7 μm3/min. The original Cu3Sn phase exhibited two preferred orientations of [100] and [203], while the Cu41Sn11 phase did not exhibit the apparent grain orientation. Various temperatures had specific effects on the kinetics and the orientation: The newly formed Cu41Sn11 grains were used to maintain the coherent or semi-coherent interface ((111)F//(100)P and [101]F//[010]P) and reduce the interfacial energy, which resulted in the step-growth mechanism during the early stage noted at 540 °C (lower temperature); by contrast, non-coherent interface between Cu3Sn and Cu41Sn11 was formed during the higher temperature (580 °C), which also resulted in the formation of more small-size cores with large amounts of grain boundaries without apparent orientation; their mechanism of growth was controlled by the grain boundary diffusion.

Tumor growth inhibition modeling to support the starting dose for dacomitinib.

Dacomitinib is a second-generation, irreversible EGFR tyrosine kinase inhibitor for first-line treatment of patients with metastatic non-small cell lung cancer and EGFR-activating mutations. A high rate of dose reductions in the pivotal trial led to an observed inverse exposure-response (ER) relationship with the primary end points. Three ER models were developed to determine if the starting dose from the pivotal trial, 45 mg once daily (q.d.) dose, is appropriate: a longitudinal logistic regression model for adverse event-related dose changes, a Claret tumor growth inhibition (TGI) model, and a Cox model for progression-free survival (PFS) based on the TGI model predictions. This analysis included 266 patients taking dacomitinib with a starting dose of 45 mg (N=250) or 30 mg (N=16) q.d. The ER relationships with the time-varying exposure metrics, most recent maximum plasma concentration (Cmax ) and average concentration (Cavg ) from the first dose, were established for the dose reduction and TGI models, respectively. The TGI model characterized the tumor inhibition over time with constant growth rate (kL =0.0012 years-1 ) and highly variable kill rate (kD =1.002 years-1 /[μg/L]θcavg , coefficient of variation [CV]=89%) and drug resistance (λ=14.47 years-1 , CV=96%) leading to prolonged tumor shrinkage. The ER relationship was characterized using an exposure parameter with a power parameterization (θcavg=0.454, p < 0.0001). The Cox model found that baseline tumor size (p=0.0166) and week 8 tumor shrinkage rate (p=0.0726) were the best predictors of PFS. Simulations of dose reductions and drug interruptions on tumor shrinkage over time showed greater and more prolonged tumor shrinkage with a starting dose of 45 mg q.d.

Beta‐Dependent Constraints on Ion Temperature Anisotropy in Jupiter’s Magnetosheath

AbstractMost space plasmas are weakly collisional. Due to the low collision rate, the plasmas are routinely out of local thermal equilibrium and often exhibit non‐Maxwellian velocity distributions. The charged particles typically exhibit anisotropy in temperature measurements, that is, distinct temperatures are observed perpendicular and parallel (T⊥i and T||i) to the local magnetic field. Numerous prior studies have shown that for increasing values of parallel ion beta (β||i), the range of ion temperature anisotropy (Ri = T⊥i/T||i) values becomes narrower. Conventionally, this behavior has been attributed to the actions of kinetic microinstabilities. This study is the first to explore such β||i‐dependent limits on ion temperature anisotropy in Jupiter's magnetosheath. We use linear Vlasov theory to compute contours of constant growth rate for different instability thresholds, which closely align with the limits of the data distribution, supporting that these instabilities are acting to limit extremes of ion temperature anisotropy in the Jovian magnetosheath.

Greigite (Fe3S4) Formation in Artificial Sediments via Solid‐State Transformation of Lepidocrocite

AbstractGreigite (Fe3S4) is a ferrimagnetic iron‐sulfide mineral that forms in sediments during diagenesis. Greigite growth can occur diachronously within a stratigraphic profile, complicating or overprinting environmental and paleomagnetic records. An important objective for paleo‐ and rock‐magnetic studies is to identify the presence of greigite and to discern its formation conditions. Greigite detection remains, however, challenging and its magnetic properties obscure due to the lack of pure, stable material of well‐defined grain size. To overcome these limitations, we report a new method to selectively transform lepidocrocite to greigite via the intermediate phase mackinawite (FeS). In‐situ magnetic characterization was performed on discrete samples with different sediment substrates. Susceptibility and chemical remanent magnetization increased proportionally over time, defining two distinct greigite growth regimes. Temperature dependent and constant initial growth rates indicate a solid‐state FeS to greigite transformation with an activation energy of 78–90 kJ/mol. Low and room temperature magnetic remanence and coercivity ratios match with calculated mixing curves for superparamagnetic (SP) and single domain (SD) greigite and suggest ∼25% and ∼50% SD proportions at 300 and 100 K, respectively. The mixing trend coincides with empirical data reported for natural greigite‐bearing sediments, suggesting a common SP endmember size of 5–10 nm that is likely inherited from mackinawite crystallites. The average particle size of 20–50 nm determined by X‐ray powder diffraction and electron microscopy accords with theoretical predictions of the SP/SD threshold size in greigite. The method constitutes a novel approach to synthesize greigite and to investigate its formation in sediments.

Potential Contamination Of High-Speed Dental Handpiece By Spray Impact On The Mouth Surface

Portable dentistry devices allow medical dentists to perform procedures on patients in their homes. However, considering the recent pandemic context, these procedures raise concerns regarding the potential of infection since high-speed dental handpieces use water sprays to cool the rotating tool. The water spray droplets impacting the mouth of an infected patient can, thus, become a contamination source. Therefore, to produce reliable data to develop numerical models of aerosol propagation, this work uses a Phase-Doppler Interferometer to characterize the water spray before impact and the application of spray impact models indicates that 80% of droplets are in the conditions to deposit on the mouth's soft tissues and 19% of droplets should rebound. While a mere 1% expects to generate splashing events, the liquid film stripping and the complex 3D flow emerging from dragging the surrounding air generates a spray exiting the mouth. This spray is different from the original, thus, it is the result of shear-driven film stripping. The mathematical function that best describes all sprays was the Log-Normal and this work explains it as the result of an exponential drop size diversity growth rate (Φ). Therefore, while the characteristic size is reasonably understood in its physical meaning, the standard deviation (s) acquires one, i.e., it is a measure of the constant drop size diversity growth rate (s ≡ Φ). This could be a relevant insight to the physical interpretation of fitting a Log-Normal probability density function to describe the distribution of drop sizes in sprays. Finally, a scale analysis of the rebound contact time using a simple diffusion model, indicates that these droplets can also become contaminants agents.

Effects of Initial Morphology on Growth Kinetics of Cu6Sn5 at SAC305/Cu Interface during Isothermal Aging.

Solder/Cu joints are important components responsible for interconnection in microelectronics. Construction of the solder/Cu joints through liquid/solid (L/S) reactions accompanies the formation of the Cu–Sn intermetallic compounds (IMCs) at the joint interface. The Cu6Sn5 IMC exhibits remarkable distinctions in thickness and morphology upon increasing the L/S reaction time. Effects of the initial characteristics of thickness and morphology on the growth kinetics of Cu6Sn5 during subsequent isothermal aging were investigated. SAC305 solder was reflowed on a Cu electroplated layer at 265 °C for 1 to 60 min to produce the Cu6Sn5 IMC with different thickness and morphology at the SAC305/Cu interface. The as-fabricated SAC305/Cu joint samples were aged at 200 °C for 72 to 360 h to investigate the growth kinetics of Cu6Sn5. The results show that the initial characteristics of thickness and morphology significantly influenced the growth kinetics of Cu6Sn5 during the subsequent solid/solid (S/S) reaction. A prolonged L/S reaction time of 60 min (L/S-60) produced a scallop-type Cu6Sn5 IMC with a larger grain size and a thicker thickness, which reduced the quantity of fast diffusion path (grain boundary) and the magnitude of concentration gradient, thus slowing down the growth rate of Cu6Sn5. According to the growth kinetics analysis, the growth rate constant of Cu6Sn5 could be remarkably reduced to 0.151 µm/h0.5 for the L/S-60 sample, representing a significant reduction of 70 % compared to that of the L/S-1 sample (0.508 µm/h0.5 for L/S reaction time of 1 min).

Fluctuations in growth are heritable and a potential indicator of resilience in Nile tilapia (Oreochromis niloticus)

Resilience can be defined as the capacity of an animal to be minimally affected by perturbations or to quickly recover to the state it had before the perturbation. When applied to production animals, resilience is defined as consistency in production over time. This consistency can be quantified by the variance of deviations from the expected trait level measured at multiple time points. The objectives of this study were to estimate genetic parameters for resilience in Nile tilapia, measured as consistency in growth. We used log-transformed variance of deviations (LnVar) of body weight measured five times during grow-out in either an aerated or a non-aerated pond. The hypothesis was that fish grown in non-aerated ponds are more challenged by environmental conditions, such that heritable variation in LnVar of body weight is more expressed showing larger differences between more and less resilient fish. The heritability for LnVar was 0.10 in aerated pond and 0.12 in the non-aerated pond. In aerated ponds the genetic correlation (rg) of LnVar with harvest weight (HW) was 0.36 ± 0.26, and with thermal growth coefficient (TGC) it was 0.47 ± 0.21. In the non-aerated pond, the rg with HW and TGC were close to zero (−0.01 ± 0.29 and − 0.08 ± 0.22). The genetic correlation for LnVar between both environments was 0.80. These estimates suggest that selection for HW or TGC in aerated ponds will increase LnVar in both environments. Increased LnVar may decrease resilience and this will be detrimental to performance. Selecting for more resilient fish would lead to more constant growth rates, which makes biomass estimation more accurate and could therefore result in more optimal feeding regimes and less feed waste. This would have a favorable effect on the feed efficiency in production units and on the environmental impact of fish farming. To improve resilience together with growth we recommend that fish breeding programs collect repeated records on body weight, preferably in challenging environments.

Modelling Nannochloropsis gaditana Growth in Reactors with Different Geometries, Determination of Kinetic Parameters and Biochemical Analysis in Response to Light Intensity

Microalgae are unicellular and photosynthetic microorganisms which grow thanks to inorganic salts, CO2 and light, and find applications in several fields thanks to their variety. The industrial application of microalgae has not often been fully exploited because of a lack of information about how microalgae respond to inputs and to different growth environments. In the present work a model able to predict the microalgae growth in reactors with different geometries was developed. We combined a Monod-like model for the specific growth rate with the Lambert-Beer law of homogeneous light distribution in thick photobioreactors. Kinetic parameters related to the cultivation of the microalga Nannochloropsis gaditana were obtained, for the first time through batch cultivation under different photon flux densities inside a quasi-isoactinic photobioreactor, in order to obtain a practically homogeneous light distribution. The maximum specific growth rate and saturation constant resulted, respectively as µmax = 0.0256 h−1 and Ik = 15.28 µE s−1m−2. These parameters were applied to the model to obtain data on microalgae growth in different geometries. Model simulation results are presented and discussed. Furthermore, biochemical analysis was performed on the biomass obtained at the end of each batch cultivation, grown both under different light intensities and in reactors with different configurations. Results indicated that lipid content increases with increasing average photon flux density. The fatty acid and carotenoids profiles markedly shift when the average light intensity varies: the PUFA content decreases and the SFA content increases when the average light intensity rises, and an accumulation of carotenoids at lower photon flux densities is observed. In conclusion, the model resulted in a useful tool, able to predict the growth of the microalga Nannochloropsis gaditana in reactors with different configurations.

Deterministic approximation for the nucleation-growth type model of nanoparticle formation: A validation against stochastic simulations

A deterministic approximation method is introduced here for a complicated kinetic model that describes nanoparticle formation with nucleation and growth steps. The model starts from monomer units, some of which combine in a nucleation reaction, and the number of monomer units (n) in a kinetically effective nucleus is an unbounded integer parameter in the model. The growth steps are second-order processes between a particle and a monomer unit, the rate constant of which depends on the size of the growing nanoparticle in a way that is given in a kernel function. Four different kernels are considered: diffusion kernel (size independence), Brownian kernel (direct proportionality to the linear size), surface kernel (direct proportionality to the surface), mass kernel (direct proportionality to the volume or mass). Aggregation or coagulation are not part of the model. The approximation method works well for all four kernels and all integer values of n, and yields analytical formulas for the average and the most important moments (zeroth, first, and the one that is relevant for the kernel function) of the nanoparticle size distribution at every stage of the process. The approximation is validated against stochastic simulations using the Gillespie algorithm within the framework of the continuous time discrete state approach to stochastic kinetics. The comparison shows that the obtained analytical formulas are applicable for all practically important cases of the model and provide a way to interpret the dependence of average nanoparticle size on the ratio of the rate constants of nucleation and particle growth.

Kinetic study of thermophilic anaerobic digestion of sugarcane vinasse in a single-stage continuous stirred tank reactor

Vinasse, the liquid waste from the bottom of a bioethanol distillation column, is a potential feedstock for biogas production due to its high organic content. Vinasse is discharged at a high temperature, i.e., 60–80 °C. Therefore, thermophilic anaerobic digestion is more efficient to directly treat the vinasse at a high organic loading rate (OLR). This study investigated the performance of thermophilic anaerobic digestion on sugarcane vinasse inoculated with acclimated digested cow manure (DCM). The experiment was run at varied OLRs (1,2; 1.8 and 2.4 gCOD.L−1.day−1). The process was carried out in a continuous stirred tank reactor (CSTR) with controlled pH (7 ± 0.5) and oxidation-reduction potential/ORP (−500 ± 10 mV). During the 111 days of the experiment, we monitored the volatile fatty acids (VFA), total chemical oxygen demand (tCOD), and soluble chemical oxygen demand (sCOD), as well as methane and biogas production rates, to evaluate the reactor performance. The experimental data were fitted on the Anaerobic Digestion Model 1 (ADM 1) using the AQUASIM® software. The data were categorized in three process stages observed in this study: stabilization, enrichment, and steady-state. The kinetic parameters, i.e., the coefficient of affinity (KS,ac, KS,pro) and the specific growth rate (km,ac and km, pro), were obtained from the data fitting. The good fit of ADM 1 to the data highlighted the flexibility of ADM 1 to represent a dynamic system of a thermophilic anaerobic digestion system with simultaneous changes in both process variables and microbial composition. The data fitting gave consistently low Ks values in the lower OLR of 0.2 gCOD. L−1.day−1 up to the higher OLR of 2.4 gCOD. L−1.day−1. The Ks values, which were less than 1/1000 of the specific growth rate constants (km), indicated that the combined effects of the thermophilic condition and vinasse composition increased the microbial-substrate affinity (showed by KS) more essentially than the microbial growth rate (addressed by km). In addition, inhibitory effects were not observed with all OLR values tested in this study.

Kinetic insights into the effect of promoters on Co/Al2O3 for Fischer-Tropsch synthesis

The fundamentals of promoter effects in the Fischer − Tropsch synthesis over Co-based catalysts were systematically investigated by employing the Rh, Ir, Sb and Ga as promoters of Co/Al2O3. Various characterizations showed the higher dispersion and reducibility over Rh- and Ir- promoted catalysts would cause a promoted adsorption property, while the Sb- and Ga- promoted catalysts showed a contrary result because the formation of alloy suppressed the accessibility of Co species. Based on the experimental results and kinetic calculations, a linear relationship for the activation energies of these catalysts as a function of activation entropies was proposed. Besides, steady state isotopic transient kinetic analysis (SSITKA) revealed that promoters mainly affected the surface CHx concentration to alter the CO reaction rate, and the chain growth rate constants would affect the product distribution. Since CoRhA and CoIrA greatly enhanced the CHx concentration and inhibited the chain growth ability, they owned a higher CO reaction rate and CH4 selectivity. While the CoSbA and CoGaA suppressed the CHx concentration and intrinsic activity, but enhanced the chain growth ability, thereby revealing a lower CO reaction rate and CH4 selectivity. Furthermore, the reactivity and selectivity difference were attributed to the modification of adsorption strength dictated by the enthalpy of activation on cobalt catalysts with different promoters. These findings provide kinetic insights into the promoter effects and pave the way for optimizing catalysts.

Special regularities for lowering temperature during growth of high-quality CdTe semiconductor layers

To obtain epitaxial layers of A2B6 semiconductors with increased structural perfection from their own liquid phase, it has been proposed to use a technological process in which the synthesis temperature varies in such a manner that ensures a constant growth rate of layers during the whole process. The regularities of temperature variation with time for this process have been found on the basis of diffusion crystallization model. The developed model is realized by numerical methods and applied to description of the growth of cadmium telluride layers. Quantitative data on variations of synthesis temperature have been obtained, which can serve as a basis for choosing the temperature-time regimes of growth of cadmium telluride layers with a constant and required rate of solid phase formation.

Surgery, Chemotherapy and Radiotherapy May Promote Cancer Growth Speeds and Shorten Patient Lives

Medicine fails to find predictable cures for cancer in more than a century, and we explored the feasibility of controlling cancer growth speed by using lifestyle factors. After conducting an extensive literature review, we conducted simulations for cancer growth courses to see the feasibility of controlling cancer growth speeds. We found that (1) medical treatments are often accompanied by three to four lethal factors: treatment side-effects, emotional distress, and chronic stress, reduced exercises and physical inactivity, and excessive nutrition in some cases; (2) clinical trial exaggerates treatments short-term benefits and underestimates the slow-delivering adverse side effects as a result of statistical averaging, interfering effects of personal lifestyle factors and insufficient follow-up times; (3) the benefits of medical treatments are limited by chain comparisons, where surgery may work as a negative standard relative to the best alternatives for resolving cancer; (4) the strategy of destroying the tumor or killing all cancer cells is unworkable; (5) medical treatments can turn natural cancer growth curve into approximately doubly exponential curve; (6) multiple-factor non-medical measures are potentially much more powerful than medical treatments in controlling cancer growth and metastasis speeds; and (7) cancer early diagnosis and over treatments are unwise strategies in light of discoveries. Based on huge increases in cancer growth rate constants, substantial loss of vital organ functional capacity, and severe systemic aging-like cellular damages, we concluded that medical treatments may promote cancer growth and metastasis speeds and shorten patient lives in most situations, and the claimed benefits are caused by triple biases of clinical trials. By using the same method to explore how several lifestyle factors affect cancer growth rates, we concluded that the better strategy for ending the global cancer epidemic in the future is changing caner treatment strategy from killing cancer cells to slowing down cancer growth rates by using various lifestyle factors in combination. This study in part explains why cancer can self-resolve.

Time-dependent crack propagation in concrete under constant loading

This paper presents an experimental study on the fracture characteristics of concrete under constant loading, focusing on the crack propagation and the unstable fracture criterion. The test involves three-point bending (TPB) notched beams and compact tension (CT) specimens with different heights, and four constant loads are considered. The results show that the specimens fail within 0.37–4566 h and a higher constant load results in a shorter lifetime of concrete. Furthermore, the time-dependent crack mouth opening displacement and crack length, CMOD(t) and a(t), show three stages with the loading time, t. In the first stage, CMOD(t) and a(t) increase rapidly whereas their growth rates decrease. In the second stage, CMOD(t) and a(t) increase at constant growth rates, indicating cracks propagate stably. In the third stage, CMOD(t) and a(t) increase at greater growth rates than those in the second stage and the growth rates are increasing, indicating the unstable fracture occurs. Accordingly, the time of the boundary point between the second and third stages is defined as the critical time of the unstable fracture of concrete under constant loading, tc. CMOD(tc) and a(tc) are found to be greater than the critical CMOD and effective crack length under static loading, CMODc and ac, and decrease with increasing the constant load. Moreover, it is found that the unstable fracture toughness of concrete under static loading, KunIC, can also be used to determine whether the unstable fracture occurs under constant loading, i.e., when the stress intensity factor at tc reaches KunIC, the unstable fracture occurs.

Artificial intelligence in energy industry: forecasting electricity consumption through cohort intelligence & adaptive neural fuzzy inference system

ABSTRACT Demand forecasting is critical for energy systems, as energy is difficult to store and should only be supplied as needed. Researchers attempted to improve forecasts of energy consumption. However, they assume independent factors increase at a constant growth rate, which is unrealistic. Existing methods are designed to determine annual consumption, whereas energy-planning organizations rely on short- or medium-term consumption values. Therefore, we propose a new forecasting framework that introduces new models and scenarios. We apply a cohort intelligence-based adaptive neuro-fuzzy inference system (CI-ANFIS) with a subtractive clustering and grid partition approach to forecast net electricity consumption. One challenge in accurately predicting electricity consumption for specific projection intervals is missing values for factors independent of those known for existing net consumption. Then, we utilize a regression equation scenario approach. We test our framework using a real-world energy consumption dataset and show that our proposed framework outperforms the existing methods.

Atomic Layer Deposition of the Conductive Delafossite PtCoO2

AbstractThe first atomic layer deposition process for a ternary oxide is reported, which contains a metal of the platinum group, the delafossite PtCoO2. The deposition with the precursors trimethyl‐Pt‐methylcyclopentadienyl, Co‐bis(N‐t‐butyl‐N′‐ethylpropanimidamidate), and oxygen plasma results in a process with a nearly constant growth rate and stoichiometric composition over a wide temperature window from 100 to 320 °C. Annealing of the as‐deposited amorphous films in an oxygen atmosphere in a temperature window from 700 to 800 °C leads to the formation of the delafossite phase. Very thin films show a pronounced preferred orientation with the Pt sheets being almost parallel to the substrate surface while arbitrary orientation is observed for thicker films. The conformal coating of narrow trenches highlights the potential of this atomic‐layer‐deposition process. Moreover, heterostructures with magnetic films are fabricated to demonstrate the potential of PtCoO2 for spintronic applications.

Assessment of two cichlids stocks with virtual population analysis in Garmat Ali River, Basrah, Iraq

The study is an attempt to evaluate the population characteristics and virtual population analysis (VPA) of two invasive species (Oreochromis niloticus and Oreochromis aureus) using the FiSAT II software based on the data collected from the Garmat Ali River, Iraq. A total of 4391 individuals (2727 of O. niloticus and 1664 of O. aureus) were measured for length-frequency analysis from October 2019 to September 2020. Length-weight relationships were derived, indicating allometric growth for both species. The asymptotic length (L∞) and growth rate constant (K) were estimated to be 30.5 cm and 0.45 for O. niloticus and 29.9 cm and 0.21 for O. aureus. The annual rates of fishing (F) and exploitation (E) for O. niloticus were found to be 2.24 and 0.69, respectively, and for O. aureus 0.48 and 0.43, respectively. The present exploitation rates (E) of both species were below the biological target reference points, E0.1 and Emax, thus expressing a case of under-exploitation of both species. Besides, the result of the virtual population analysis (VPA) revealed that the majority of O. niloticus and O. aureus individuals were harvested at lengths 20 cm and 17 cm, respectively. Also, the lengths at first capture (L50) for both species were considerably higher than their lengths at first maturity (Lm). Therefore, for management purposes, this study suggests that more yields can be obtained by increasing the fishing activities on these invasive species, such as increasing the number of fishing boats and decreasing the mesh size to decline its abundance in the long term.

Comments on Mathematical Aspects of the Biró–Néda Model

We address two mathematical aspects of the Biró–Néda dynamical model, recently applied in the statistical analysis of several and varied complex phenomena. First, we show that a given implicit assumption ceases to be valid outside the most simple and common cases, and we analyze the consequences thereof, in what the formulation of the model and probability conservation is concerned. Second, we revisit the transient behavior in the case of a constant reset rate and a constant or linear growth rate, improving on a previous analysis by including more general initial conditions.