Initial Growth Rate Research Articles

Monitoring, modelling and managing beaver (Castor fiber) populations in the River Otter catchment, Great Britain

Abstract Eurasian beaver (Castor fiber) were nearly hunted to extinction but have recovered to occupy much of their former range. Beaver were extirpated from Great Britain c. 400 years ago but have recently been reintroduced. The River Otter catchment, Devon was the site of the first licensed wild release of beavers in England. With further releases being considered, there is a need to better understand population dynamics of this native, keystone species to inform conservation and management. Field signs were surveyed from 2015 to 2021. A semi‐automated territory detection method was adopted to estimate territory counts. A spatially explicit model was developed to estimate the ecological territory capacity of the catchment. Future territory expansion was modelled using logistic growth curves; initial growth rate was estimated from observed territory counts and the estimated territory capacity range was used to define the limiting value of the growth curve. Beaver territory removal was simulated, across a range of management intensities and start times, to determine potential impacts of translocation or lethal control upon population dynamics. Territory numbers increased from four to 18, inclusive of four additionally released individuals, during study period. In the absence of population management, the territory capacity of the catchment was estimated to range between 120 and 183; this may be reached between 2028 and 2057. Simulated territory removal, where territories were removed at a fixed rate from the sum of the estimated total population and the population increase for that year, demonstrated large uncertainties in predicted population responses. Simulations with territory removals >3/year all predicted potential population collapse. This finding emphasizes the need for caution when considering population management strategies; translocation of animals out of the catchment or culling should be considered only when populations are established and all alternatives have been considered. These results provide critical information for the expected rate and magnitude of beaver population change in the River Otter catchment. The methods provide a reproducible and generalizable approach for understanding beaver population change, which can inform policy on the reintroduction of beavers and the potential timing and intensity of future beaver population management.

Growth and shedding of harbor seal (Phoca vitulina) whiskers

Accurate and precise estimates of the timing of whisker growth and shedding are necessary to interpret biochemical information stored in whiskers. This fine-scale examination of harbor seal ( Phoca vitulina Linnaeus, 1758) whisker growth and shedding identified an asymptotic growth pattern with initial rapid growth that decays over time that can be defined with the von Bertalanffy curve. Initial growth rates were similar among whiskers, but estimated growth coefficients ( K) and asymptotic lengths ( L∞) differed by follicle positions suggesting that differences in total whisker lengths result from dissimilarly shaped growth curves. In other words, longer whisker length is attained by delaying the growth rate decay. There was substantial intra- and interseal variation in shedding dates; whisker shedding began at the caudal margin of the whisker bed and progressed toward the nose. Shedding of marked whiskers from the three study seals took from 78 to 133 days; however, selecting whiskers only from the most caudal follicle of the bottom three rows constrained the period of whisker shedding to 7–43 days. These differences in growth and shedding of harbor seal whiskers emphasize the importance of considering follicle position to select whiskers that are the most similar for analyses of information stored in whiskers.

Assessment of the combined pesticide and cadmium load on the soil using higher plants

The multicomponent nature of agroecosystem pollution complicates the effectiveness of the ecotoxicological control. The danger of the combined pesticide and cadmium soil load was investigated in the laboratory conditions using agricultural plants (test crops). The aim of the study was an integral assessment of the complex impact of pesticide and cadmium soil contamination on wheat Triticum aestivum L. by biotesting. The widely used pesticides in agriculture were tested: systemic fungicides Azimut (a.i.: tebuconazole, 125 g/dm³ + triadimefon, 100 g/dm³), Azimut Classic (a.i.: tebuconazole, 250 g/dm³) and soil-acting herbicide Extrabit (a.i.: S-metolachlor, 960 g/dm³). The levels of Cadmium accumulation by plants (by inductively coupled plasma atomic emission spectroscopy) and pesticide active ingredients (by high-performance liquid chromatography with a mass detector) were determined. It was found that a exceeding the rate of pesticide application leads to their accumulation by plants. At combined soil load with Cadmium (3-fold maximum allowable concentration, MAC) and the associated pesticide, an increase in the accumulation of active ingredients by plants is observed (tebuconazole by 1.85 and 1.47 times for Azimut and Azimut Classic, respectively, and S-metolachlor by 1.47 times for Extrabit) compared to a single pesticide. In addition, phytotoxicity of pesticides was noted in the conditions of the experiment. Thus, for the fungicide Azimut and the herbicide Extrabit, a decrease in the initial growth rate of plants (length of roots and seedlings) by more than 40 % was found, which indicates a level of phytotoxicity above average. It was concluded that new pesticide formulations (including soil-acting pesticides) should be tested for toxicity in relation to higher plants. This is important for development of countermeasures to reduce pesticide accumulation in agricultural plants, especially in conditions of soil contamination with heavy metals. Key words: biotesting, combined action, pesticides, cadmium, phytotoxicity, Triticum aestivum L.

Modeling the effect of gut microbiome on therapeutic efficacy of immune checkpoint inhibitors against cancer

Immune checkpoint inhibitors have been shown to be highly successful against some solid metastatic malignancies, but only for a subset of patients who show durable clinical responses. The overall patient response rate is limited due to the interpatient heterogeneity. Preclinical and clinical studies have recently shown that the therapeutic responses can be improved through the modulation of gut microbiome. However, the underlying mechanisms are not fully understood. In this paper, we explored the effect of favorable and unfavorable gut bacteria on the therapeutic efficacy of anti-PD-1 against cancer by modeling the tumor-immune-gut microbiome interactions, and further examined the predictive markers of responders and non-responders to anti-PD-1. The dynamics of the gut bacteria was fitted to the clinical data of melanoma patients, and virtual patients data were generated based on the clinical patient survival data. Our simulation results show that low initial growth rate and low level of favorable bacteria at the initiation of anti-PD-1 therapy are predictive of non-responders, while high level of favorable bacteria at the initiation of anti-PD-1 therapy is predictive of responders. Simulation results also confirmed that it is possible to promote patients’ response rate to anti-PD-1 by manipulating the gut bacteria composition of non-responders, whereby achieving long-term progression-free survival.

The impact of three progressively introduced interventions on second wave daily COVID-19 case numbers in Melbourne, Australia

BackgroundThe city of Melbourne, Australia experienced two waves of the COVID-19 epidemic peaking, the first in March and a more substantial wave in July 2020. During the second wave, a series of control measure were progressively introduced that initially slowed the growth of the epidemic then resulted in decreasing cases until there was no detectable local transmission.MethodsTo determine the relative efficacy of the progressively introduced intervention measures, we modelled the second wave as a series of exponential growth and decay curves. We used a linear regression of the log of daily cases vs time, using a four-segment linear spline model corresponding to implementation of the three successive major public health measures. The primary model used all reported cases between 14 June and 15 September 2020 then compared the projection of the model with observed cases predicting future case trajectory up until the 31 October 2020 to assess the use of exponential models in projecting the future course and planning future interventions. The main outcome measures were the exponential daily growth constants, analysis of residuals and estimates of the 95% confidence intervals for the expected case distributions, comparison of predicted daily cases.ResultsThe exponential growth/decay constants in the primary analysis were: 0.122 (s.e. 0.004), 0.035 (s.e. 0.005), − 0.037 (s.e. 0.011), and − 0.069 (s.e. 0.003) for the initial growth rate, Stage 3, Stage 3 + compulsory masks and Stage 4, respectively. Extrapolation of the regression model from the 14 September to the 31 October matched the decline in observed cases over this period.ConclusionsThe four-segment exponential model provided an excellent fit of the observed reported case data and predicted the day-to-day range of expected cases. The extrapolated regression accurately predicted the decline leading to epidemic control in Melbourne.

Plasma enhanced chemical vapor deposition of p-type Cu2O from metal organic precursors

The scope of this work was to optimize the reactant delivery parameters for the plasma enhanced chemical vapor deposition (PECVD) of p-type Cu2O films from Cu(hfac)(tmvs), with the aim to explore an alternative to other large-area deposition techniques such as sputtering. While n-type metal oxide semiconductors such as amorphous indium gallium zinc oxide have now been developed and offer significantly improved device performance over hydrogenated amorphous silicon, with devices achieving mobilities >10cm2(Vs)−1, there is still an absence of good p-type inorganic semiconductors that provide similar performance. Cu2O is a promising p-type metal oxide, but there remain limitations on the industrial scalability of some of the deposition processes demonstrated so far. PECVD has been scaled for uniform deposition on generation 10 display glass (2.88×3.13m2) and so provides a viable alternative. The Cu2O films deposited in this work achieved a Hall mobility of ∼1cm2(Vs)−1 and were stable over a period of months. Contrary to previous reports of an “incubation” period, the initial growth rate during and immediately following nucleation was (∼40 nm/pulse) 10 times greater than the steady state growth (∼4 nm/pulse) achieved later in the deposition. Topographical scaling methods and fractal analysis of the film surface morphology using atomic force microscopy, at different stages during growth development, link this shift to a regime transition from growth dominated by surface diffusion to volume diffusion.

Combustion and flame position impacts on shear layer dynamics in a reacting jet in cross-flow

This study experimentally investigates reacting jets in cross-flow (RJICF), considering flame/shear layer offset, momentum flux ratio ( $J$ ) and density ratio ( $S$ ) effects. These results demonstrate that non-reacting JICF and RJICF can exhibit very similar or completely different dynamics and controlling physics, depending upon streamwise and radial flame location. Consistent with prior measurements of Getsinger et al. (Exp. Fluids, vol. 53 (3), 2012, pp. 783–801), spatial amplification rates of shear layer vortex (SLV) structures increased with decreasing $S$ for non-reacting cases. Similar $S$ dependencies exist for reacting cases in which the flame lay outside the jet shear layer, whose flow topology is also quite similar to non-reacting cases, albeit with reduced SLV growth rates. However, although the reacting cases have lower growth rates, these SLV structures ultimately reach approximately the same peak strength as in the non-reacting cases. Finally, the SLV decay rate in both non-reacting and reacting cases was found to similarly scale inversely with the initial SLV growth rate. As such, primarily inertial mechanisms govern SLV growth and decay for reacting cases where the flame lies outside the shear layer. In contrast, very different behaviour is exhibited by reacting cases where the flame lies inside the shear layer, where the locally increased viscosity exerts significant influences. In these reacting cases, SLV roll-up is completely suppressed and the entire jet column undulates over a long length scale relative to the jet diameter. As such, the relative roles of inertial and viscous mechanisms in controlling combustion influences on the SLV dynamics, changes markedly with shear layer–flame offset.

Крупноплодный сорт подсолнечника кондитерского направления Кондитер

The large-seeded sunflower variety Konditer was developed at V.S. Pustovoit All-Russian Research Institute of Oil Crops as part of the breeding program for developing varieties of different maturity groups, directions of use and resistance to stressful environment conditions. The variety Konditer belongs to the middle maturity group. The period from seedling to physiological maturity is 96–98 days. Its feature is a potentially high yield, resistance to the complex of broomrape races E, F, G. The plant height is 190–200 cm. The new variety is characterized by high initial growth rate and high germination energy. Thousand-seed weight varies within 100 g at a density of 40 thousand plants/ha, under the recommended density of 25–30 thousand plants/ha, the thousand-seed weight is more than 150 g. Dehulling ability of the variety Konditer is the same as that of the standard variety Dzhinn. The variety Kodniter has been in-cluded in the State Register of Breeding Achieve-ments of the Russian Federation since 2022 and is approved for cultivation in the Central Black Earth (5), North Caucasus (6), Middle Volga (7), and Lower Volga (8) regions.

The Correlation for Effective Distribution Coefficient with Initial Impurity Concentration and Growth Rate for Acrylic Acid in Melt Crystallization

The layer growth rates and resulting crystal purity during solid-layer melt crystallization were experimentally measured for acrylic acid (AA) with impurity propionic acid (PA) operated at various cooling temperatures. A power law was adopted to correlate the growth rate with the temperature difference between melt and coolant. The effective distribution coefficient was determined from the resulting crystal purity for each condition. An empirical equation modified from the analytical solution for the mass transfer boundary layer was proposed in this work to relate the effective distribution coefficient to the initial impurity concentration and growth rate.

Face masking and COVID-19: potential effects of variolation on transmission dynamics.

Face masks do not completely prevent transmission of respiratory infections, but masked individuals are likely to inhale fewer infectious particles. If smaller infectious doses tend to yield milder infections, yet ultimately induce similar levels of immunity, then masking could reduce the prevalence of severe disease even if the total number of infections is unaffected. It has been suggested that this effect of masking is analogous to the pre-vaccination practice of variolation for smallpox, whereby susceptible individuals were intentionally infected with small doses of live virus (and often acquired immunity without severe disease). We present a simple epidemiological model in which mask-induced variolation causes milder infections, potentially with lower transmission rate and/or different duration. We derive relationships between the effectiveness of mask-induced variolation and important epidemiological metrics (the basic reproduction number and initial epidemic growth rate, and the peak prevalence, attack rate and equilibrium prevalence of severe infections). We illustrate our results using parameter estimates for the original SARS-CoV-2 wild-type virus, as well as the Alpha, Delta and Omicron variants. Our results suggest that if variolation is a genuine side-effect of masking, then the importance of face masks as a tool for reducing healthcare burdens from COVID-19 may be under-appreciated.

Heterogeneous Rate Constant for Amorphous Silica Nanoparticle Adsorption on Phospholipid Monolayers.

The interaction of amorphous silica nanoparticles with phospholipid monolayers and bilayers has received a great deal of interest in recent years and is of importance for assessing potential cellular toxicity of such species, whether natural or synthesized for the purpose of nanomedical drug delivery and other applications. This present communication studies the rate of silica nanoparticle adsorption on to phospholipid monolayers in order to extract a heterogeneous rate constant from the data. This rate constant relates to the initial rate of growth of an adsorbed layer of nanoparticles as SiO2 on a unit area of the monolayer surface from unit concentration in dispersion. Experiments were carried out using the system of dioleoyl phosphatidylcholine (DOPC) monolayers deposited on Pt/Hg electrodes in a flow cell. Additional studies were carried out on the interaction of soluble silica with these layers. Results show that the rate constant is effectively constant with respect to silica nanoparticle size. This is interpreted as indicating that the interaction of hydrated SiO2 molecular species with phospholipid polar groups is the molecular initiating event (MIE) defined as the initial interaction of the silica particle surface with the phospholipid layer surface promoting the adsorption of silica nanoparticles on DOPC. The conclusion is consistent with the observed significant interaction of soluble SiO2 with the DOPC layer and the established properties of the silica–water interface.

Growth analysis of broilers fed by diets containing different oils

Objective of this study is to evaluate growth pattern of boilers fed diets containing different oils. Data for this study were obtained from an experiment involving 160 unsexed one day old chicks of Ross 308 cross randomly allocated to four dietary treatments (n=40) with five replicates in each of them (eight birds per replicate) over 42 days. Feeding experimental diets was introduced in the last 21 days. Composition of experimental diets (C, D1, D2 i D3) was the same, containing different levels of added oils. Control diet contained 6% of sunflower oil. D1, D2 and D3 diets contained added oils in the following combinations: 1% fish oil + 2% linseed oil + 3% rapeseed oil (D1), 1.5% fish oil + 1.5% linseed oil + 3% rapeseed oil (D2) and 2% fish oil + 1% linseed oil + 3% rapeseed oil (D3). All diets were isoenergetic and contained 0.015% vitamin E. Gompertz model fits the data obtained from weekly weighing of birds. The model indicated high accuracy with the determination coefficient of over 99.9%. Predicted mature weight of birds, initial specific growth rate per week, rate of exponential decay of the initial specific growth rate, age of birds at inflection point, weight at the inflection point, and maximum weight gain at inflection point for each dietary treatment were subjected to one-way variance analysis. A positive effect of dietary omega-3 fatty acids on most of examined growing curve parameters has been established.

Assortative mixing among vaccination groups and biased estimation of reproduction numbers

Assortative mixing among vaccination groups and biased estimation of reproduction numbers

Kingfish (Seriola lalandi) adjust to low salinity with only subtle effects to cardiorespiratory and growth performance

At reduced salinities nearing isosmotic conditions, marine fishes experience reduced osmotic gradients between body fluids and the surrounding water, which should lower energetic costs of osmoregulation. Such energy savings on osmoregulation can potentially be directed to other processes such as growth, suggesting the possibility that rearing euryhaline fishes under reduced salinity in aquaculture may be a beneficial practice. The yellowtail kingfish (Seriola lalandi) is one such aquaculture species that appears to benefit from low salinity, as juveniles display faster growth when reared at salinities approaching isosmotic conditions. Here, we tested the hypothesis that, due to reduced osmoregulatory costs, growth is improved in sub-adult kingfish reared at low salinity, and this is associated with a down-regulation of resting cardiorespiratory activity reflecting energetic savings. Furthermore, to gain a more complete picture of how low salinity impacts cardiorespiratory function in kingfish, we also assessed maximal cardiorespiratory responses to enforced exercise. Two experiments were carried out. The first assessed resting and maximum cardiac and respiratory performance of kingfish acclimated to seawater (35 ppt), and after ~20 h (acute) or > 4 weeks (chronic) exposure to brackish water (17 ppt). Acute 17 ppt exposure reduced standard metabolic rate (i.e. resting O2 consumption rate; 179.4 mg O2∙h−1∙kg−1) relative to fish maintained in seawater (198.3 mg O2∙h−1∙kg−1), but this difference was no longer apparent following chronic acclimation to 17 ppt (191.3 mg O2∙h−1∙kg−1). While maximum metabolic rate was not affected by salinity, kingfish both acutely transferred and acclimated to 17 ppt had a reduced excess post-exercise O2 consumption compared to fish in 35 ppt. Acclimation to 17 ppt was also associated with a reduced proportion of ventricle compact myocardium. In a second experiment, we analyzed growth rate and feed conversion efficiency of kingfish acclimated to seawater (35 ppt) or brackish water (24 and 12 ppt) for 8 weeks. Contrary to our initial hypothesis, growth rate and feed conversion efficiency were slightly deteriorated (by ~5 and ~ 6% for growth rate and feed conversion efficiency, respectively) after 4 weeks acclimation to 12 ppt; however, these differences were no longer apparent after 8 weeks acclimation. This study shows neither substantial benefits nor costs of brackish water exposure to cardiorespiratory and growth performance in sub-adult kingfish, suggesting this species can be reared at salinities as low as 12 ppt.

A high-order spectral method for effective simulation of surface waves interacting with an internal wave of large amplitude

In this study, we propose a new method for simulating complex surface waves interacting with a large amplitude internal solitary wave. Our model is based on a high-order spectral method for surface waves with the bottom boundary conditions computed from an internal wave solver. The convergence of the model is first tested using an internal wave case without surface waves. We then perform simulations of a canonical nonlinear wave interaction case involving two surface wave components and a prescribed internal wave component. The initial wave energy growth rate of the resonant wave component is found to agree with the analytical value predicted by the perturbation theory. We also use the model to simulate the interaction between surface waves and a weakly nonlinear internal wave, and the result is nearly identical to that calculated using a two-layer model. Finally, we show the application of our model in a multiscale nested modeling framework, where the internal wave parameters are extracted from the mesoscale simulation using a nonhydrostatic ocean model. The evolution of the spatial variations of the surface roughness is captured and the surface wave orbital velocity also changes in space due to the surface motions induced by the internal wave. Our phase-resolved model provides a computationally efficient tool for simulating complex surface wave fields in the background of internal waves of large amplitudes.

Earnings dynamics and intergenerational transmission of skill

This paper develops and estimates a two-factor model of intergenerational skill transmission when earnings inequality reflects differences in individual skills and other non-skill shocks. We consider heterogeneity in both initial skills and skill growth rates, allowing variation in skill growth to change over the lifecycle. Using administrative tax data on two linked generations of Canadians covering 37 years, we exploit covariances in log earnings (at different ages) both across and within generations to identify and estimate the intergenerational correlation structure for initial skills and skill growth rates, lifecycle skill growth profiles, and the dynamics of non-skill earnings shocks.We estimate low intergenerational elasticities (IGEs) for earnings in Canada; however, skill IGEs are typically 2–3 times larger due to considerable (and persistent) variation in earnings conditional on skills. Both earnings and skill IGEs decline for more recent child cohorts and are lower for children born to younger fathers. Intergenerational transmission of both initial skills and skill growth rates explains up to 40% of children’s skill variation. Skills become a more important determinant of earnings over the first part of workers’ careers; however, intergenerational transmission of skills becomes less important as children age, because skill growth rates are not well-predicted by parental skills. Parents’ initial skills and skill growth rates are equally important determinants of children’s skills, largely because both strongly influence children’s initial skills.Finally, we study intergenerational mobility for the 35 largest cities in Canada, documenting the extent to which considerable differences in earnings and skill IGEs vary with the extent of local heterogeneity in parental skills vs. earnings instability.

Predicting the number of COVID-19 infections and deaths in USA

BackgroundUncertainties surrounding the 2019 novel coronavirus (COVID-19) remain a major global health challenge and requires attention. Researchers and medical experts have made remarkable efforts to reduce the number of cases and prevent future outbreaks through vaccines and other measures. However, there is little evidence on how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection entropy can be applied in predicting the possible number of infections and deaths. In addition, more studies on how the COVID-19 infection density contributes to the rise in infections are needed. This study demonstrates how the SARS-COV-2 daily infection entropy can be applied in predicting the number of infections within a given period. In addition, the infection density within a given population attributes to an increase in the number of COVID-19 cases and, consequently, the new variants.ResultsUsing the COVID-19 initial data reported by Johns Hopkins University, World Health Organization (WHO) and Global Initiative on Sharing All Influenza Data (GISAID), the result shows that the original SAR-COV-2 strain has R0<1 with an initial infection growth rate entropy of 9.11 bits for the United States (U.S.). At close proximity, the average infection time for an infected individual to infect others within a susceptible population is approximately 7 minutes. Assuming no vaccines were available, in the U.S., the number of infections could range between 41,220,199 and 82,440,398 in late March 2022 with approximately, 1,211,036 deaths. However, with the available vaccines, nearly 48 Million COVID-19 cases and 706, 437 deaths have been prevented.ConclusionThe proposed technique will contribute to the ongoing investigation of the COVID-19 pandemic and a blueprint to address the uncertainties surrounding the pandemic.

Do posttraumatic stress symptoms predict trajectories of sleep disturbance and fatigue in patients with breast cancer? A parallel-process latent growth model.

Using a parallel-process latent growth model (LGM), this study examined whether posttraumatic stress symptoms (PTSS) are associated with the trajectory of sleep disturbance (SD) and fatigue and whether the SD trajectory mediates the PTSS-fatigue relationship. Data were from 215 patients with breast cancer recruited from a tertiary hospital in South Korea. A self-report survey was administered at four time points during the course of adjuvant chemotherapy. The mean age of the participants was 46.69 (SD=9.08) and the majority was at stage I and the average months since diagnosis was 1.33 (SD=1.43). Unconditional parallel-process LGM indicated that SD and fatigue were positively associated with each other, both in terms of initial status and growth rate. Then, the conditional parallel-process LGM with baseline PTSS (i.e., avoidance, intrusion, and hyperarousal) as predictors were examined and anxiety, depressive symptoms and chronotype were entered as covariates in the model. Results indicated that a higher initial status and faster growth of SD were associated with a faster increase in fatigue. Greater baseline hyperarousal was directly related to a higher initial status and a slower increase in SD, and higher initial fatigue. Furthermore, a higher hyperarousal was associated with a greater initial SD, which was related to a faster increase in fatigue. Additionally, the late chronotype was related to a faster increase in fatigue through its impact on the initial SD. The detrimental impact of hyperarousal on the SD trajectory and fatigue suggests the need to intervene in PTSS and SD early and throughout the course of cancer treatments to prevent fatigue.

Innovation Research on Symbiotic Relationship of Organization’s Tacit Knowledge Transfer Network

The sustainable development of organizations is inseparable from innovation, and tacit knowledge is the core resource used to achieve organizational innovation. Due to the implicitness of tacit knowledge and the complexity of members’ relationships, symbiotic relationships between members have dramatically affected the transfer effect of tacit knowledge. However, previous studies on tacit knowledge transfer only focus on the characteristics of the subject or object; fewer consider the role of symbiotic relationships between knowledge subjects. An organization’s tacit knowledge transfer network (OTKTN) is a dynamic knowledge transfer network established among multiple members. Tacit knowledge transfer and sharing among network members conform to the symbiotic feature. To examine various relationships between members, and to investigate the mechanisms that impact tacit knowledge transfer, this article aims to analyze the symbiotic relationships in OTKTN based on the symbiotic perspective. The Lotka–Volterra model was used to construct symbiotic evolution model, and symbiotic coefficients were constructed from the four levels: knowledge-based psychological personal ownership (KPPO) of the knowledge provider, media richness, trust of the knowledge receiver, and organizational rewards matching, to discuss symbiotic modes. Finally, numerical simulation software was applied to simulate the evolution of knowledge levels in members. The results show that the four kinds of symbiotic modes between members include independence, commensalism, asymmetric mutualism, and symmetric mutualism. Symmetric mutualism is the best mode. In this mode, maximum level in independence mode affects the final stable knowledge level; the initial knowledge amount and natural growth rate both affect knowledge growth rate. Media richness, receiver’s trust, and organizational rewards matching can increase members’ tacit knowledge, but the knowledge provider’s KPPO inhibits members’ tacit knowledge growth. This article provides guidance to form a healthy symbiotic relationship and help organizations increase tacit knowledge.

Asymmetric Holmboe instabilities in arrested salt-wedge flows

The asymmetric Holmboe instabilities that form on an arrested salt wedge are investigated in the laboratory. The flow is characterized by three regions. Near the tip of the salt wedge, there is little wave activity; immediately downstream, mostly positive waves form; further downstream, both positive and negative waves are present. The appearance of these regions is determined by the spatial variation in the thickness of the saline layer, the shear layer thickness, and the offset between the density interface and velocity interface. We predict the growth of the instabilities by applying linear stability theory to the mean flow field. The predicted initial growth rate is consistent with the laboratory measurements until the Holmboe wave reaches a steepness ratio of 5–7 %. Then, the growth of the Holmboe wave is nonlinear. We found that the Holmboe wavelength increases downstream along the salt wedge. This wave stretching is related to the increase in the shear layer thickness and is supported by the gradual acceleration of the upper layer fluid. Eventually, the growth of the wave amplitude and the wave stretching balance a maximum wave steepness ratio of 10%. Although the wave is nonlinear, the predicted wave speed and wavelength are consistent with the laboratory measurements.