Exponential Growth Equation Research Articles

Dynamic magnetic characteristics of the kinetic Ising model under the influence of randomness.

In this paper, we propose to solve the issues of long-range or next-neighbor interactions by introducing randomness. This approach is applied to the square lattice Ising model. The Monte Carlo method with the Metropolis algorithm is utilized to calculate the critical temperature T_{C}^{*} under equilibrium thermodynamic phase transition conditions and to investigate the characterization of randomness in terms of magnetization. In order to further characterize the effect of this randomness on the magnetic system, clustering coefficients C_{p} are introduced. Furthermore, we investigate a number of dynamic magnetic behaviors, including dynamic hysteresis behaviors and metamagnetic anomalies. The results indicate that noise has the effect of destabilizing the system and promoting the dynamic phase transition. When the system is subjected to noise, the effect of this noise can be mitigated by the addition of a time-oscillating magnetic field. Finally, the evolution of anomalous metamagnetic fluctuations under the influence of white noise is examined. The relationship between the bias field corresponding to the peak of the curve h_{b}^{peak} and the noise parameter σ satisfies the exponential growth equation, which is consistent with other results.

Analysis of Police Personnel to Population Growth in Five Urban Local Government Areas in Ibadan Metropolis: A Panacea for Crime Free Environment

Adequate policing to the society enhances free crime and sustainable environment. This study analyses the Availability of Police Personnel to Population Growth of Persons in Five Urban Local Government Areas of Ibadan Metropolis, Oyo State, Nigeria with the purpose of determining the ratio of police personnel’s 2023 to 2023 population of persons’ for the study areas using Malthus Population Growth Model (Exponential Growth Equation). Police personnel’s data were acquire from the Police Divisional Headquarters, Eleyele, Ibadan, Nigeria. The geographic coordinates used to depict the distribution of police stations in each of the five urban local government areas was obtained from Grid3 Nigeria and processed using ArcGIS 10.4. The results revealed an accelerated increase in population in the study area. The results from this study however showed that the ratio of police personnel to population of persons does not meet up with the United Nation’s recommended ratio of 1:450. Generally, from the results, it showed that with the 2023 estimated population growth of 2,014,279 from 1,343,147 in 2006, and the required number of police personnel compared to the number obtained in 2023 from the police headquarters, as well as the number of police stations available, there is a need for the federal government in collaboration with the state government to take necessary actions and preventive control in the study areas so as to avoid constant criminal activities.

Use of dielectric properties measurements at microwave frequencies for real-time monitoring of water activity in almonds

A dielectric-based method for real-time tracking of changes in water activity in almond kernels is proposed. The method is based on measurement of the dielectric properties at a single microwave frequency. Samples of almond kernels (Butte/Padre and Nonpareil) were placed in a chamber with high humidity and their dielectric properties were measured at 10 GHz and room temperature (22 °C) every few hours. The dielectric properties increased linearly with time and exponentially with water activity. A three-parameter exponential growth equation provided relationships correlating the dielectric constant (ε’), the dielectric loss factor, (ε”), and the loss tangent (ε”/ε’) with water activity with high coefficients of determination (r2 ). From these equations, water activity calibration equations were obtained. Performance of these equations in predicting water activity under dynamic situations were assessed by calculating the standard error of calibration (SEC). Values of SEC ranged from 0.01 to 0.05.

Slow crack growth in multispectral zinc sulfide for use in aircraft window design

The slow crack growth rate and inert strength of multispectral zinc sulfide were measured for use in aircraft window lifetime analysis. Dynamic fatigue data for uncoated multispectral zinc sulfide were fit to a power law by linear regression and to an exponential law by computer-aided numerical integration to obtain best-fit slow crack growth rate parameters. For the power law slow crack growth equation, crack velocity ( v ) = A * (KI/KIc)n, we find A * = 0.00769 m / s and n = 14.65, where KI is the stress intensity factor, KIc = 0.72 MPam is the critical stress intensity factor, and we assign the value of the geometric factor to be Y = 2 / π. Parameters for the exponential law slow crack growth equation, crack velocity ( v ) = vo exp ( βKI ) are vo = 3.02 × 10 − 14 m / s and β = 43.64 (MPam) − 1. There were only small differences in the crack growth rate between uncoated and antireflection-coated material. The crack growth rate that we observe is 10 to 200 times faster than previously reported for a stress intensity factor KI = 0.25 MPam, which is a representative value of KI for an aircraft window in service. The faster crack growth rate predicts a correspondingly shorter window lifetime. The inert strength of uncoated biaxial flexure disks (38.1 mm diameter with 15.88 mm load diameter and 31.75 mm support diameter) measured in dry nitrogen exhibited a 50% Weibull failure probability at 115 MPa with an unbiased ASTM C1239 Weibull modulus of 4.68. Antireflection-coated material had a 50% Weibull failure probability at 100 MPa with a Weibull modulus of 5.25.

L-carnitine does not improve valproic acid poisoning management: a cohort study with toxicokinetics and concentration/effect relationships

BackgroundValproic acid (VPA) poisoning is responsible for life-threatening neurological and metabolic impairments. Despite only low-level evidence of effectiveness, L-carnitine has been used for years to prevent or reverse VPA-related toxicity. We aimed to evaluate the effects of L-carnitine used to treat acute VPA poisoning on the time-course of plasma VPA concentrations and VPA-related toxicity. We designed a single-center cohort study including all VPA-poisoned patients admitted to the intensive care unit. We studied VPA toxicokinetics using a nonlinear mixed-effects model-based population approach and modeled individual plasma VPA/blood lactate concentration relationships. Then, we evaluated L-carnitine-attributed effects by comparing VPA elimination half-lives and time-courses of blood lactate levels and organ dysfunction [assessed by the Sequential Organ Failure Assessment (SOFA) score] between matched L-carnitine-treated and non-treated patients using a multivariate analysis including a propensity score.ResultsSixty-nine VPA-poisoned patients (40F/29 M; age, 41 years [32–47]) (median [25th–75th percentiles]; SOFA score, 4 [1–6]) were included. The presumed VPA ingested dose was 15 g [10–32]. Plasma VPA concentration on admission was 231 mg/L [147–415]. The most common manifestations were coma (70%), hyperlactatemia (3.9 mmol/L [2.7–4.9]) and hyperammonemia (127 mmol/L [92–159]). VPA toxicokinetics well fitted a one-compartment linear model with a mean elimination half-life of 22.9 h (coefficient of variation, 28.1%). Plasma VPA (C)/blood lactate concentration (E) relationships were well described by an exponential growth equation [E={E}_{0}times {e}^{kcdot C}; with baseline E0 = 1.3 mmol/L (43.9%) and rate constant of the effect, k = 0.003 L/mg (59.5%)]. Based on a multivariate analysis, peak blood lactate concentration was the only factor independently associated with L-carnitine administration (odds ratio, 1.9, 95% confidence interval, 1.2–2.8; P = 0.004). We found no significant contribution of L-carnitine to enhancing VPA elimination, accelerating blood lactate level normalization and/or preventing organ dysfunction.ConclusionsVPA poisoning results in severe toxicity. While L-carnitine does not contribute to enhancing VPA clearance, its impact on accelerating blood lactate level normalization and/or preventing organ dysfunction remains uncertain. Investigating VPA toxicokinetics and concentration/effect relationships may help understanding how to improve VPA-poisoned patient management.

The time evolution of the large exponential and power population growth and their relation to the discrete linear birth-death process

<abstract><p>The Feller exponential population growth is the continuous analogues of the classical branching process with fixed number of individuals. In this paper, I begin by proving that the discrete birth-death process, $ M/M/1 $ queue, could be mathematically modelled by the same Feller exponential growth equation via the Kolmogorov forward equation. This equation mathematically formulates the classical Markov chain process. The non-classical linear birth-death growth equation is studied by extending the first-order time derivative by the Caputo time fractional operator, to study the effect of the memory on this stochastic process. The approximate solutions of the models are numerically studied by implementing the finite difference method and the fourth order compact finite difference method. The stability of the difference schemes are studied by using the Matrix method. The time evolution of these approximate solutions are compared for different values of the time fractional orders. The approximate solutions corresponding to different values of the birth and death rates are also compared.</p></abstract>

Formation and Prediction of PhIP, Harman, and Norharman in Chemical Model Systems Containing Epicatechin under Various Reaction Conditions.

The aim of this study was to investigate the formation rules of 1-methyl-6-phenylimidazo[4,5-b]-pyridine (PhIP), 1-methyl-9H-pyrido[3,4-b]-indole (Harman), and 9H-pyrido[3,4-b]-indole (Norharman) in chemical model systems containing epicatechin under various reaction conditions and establish their prediction models. The results indicated that at 100-200 °C and pH 5.5-7.5 for 10-90 min, epicatechin inhibited the formation of PhIP, Harman, and Norharman by 32-100, 1-93, and 5-98%, respectively. The exponential growth equation in the growth model with R2 of 0.986-0.997, the second-order equation in the polynomial model with R2 of 0.900-0.949, and the trigonometric function equation in the Fourier model with R2 of 0.513-0.926 were well fitted for the formation of PhIP, Harman, and Norharman at various temperatures, times, and pHs, respectively. The calibration set (R2c) and the prediction set (R2p) of the optimal partial least squares regression prediction model was 0.74 and 0.70 for PhIP, 0.75 and 0.70 for Harman, and 0.90 and 0.91 for Norharman, respectively. The results provide theoretical support to develop technologies or equipment for the real-time synchronous monitoring of PhIP, Harman, and Norharman during meat processing.

Mathematical modeling applied to ruminal digestion and gas production in vitro

The ruminal digestion performed by ruminants is one of the essential and most important processes for the use of dietary nutrients. However, the use of mathematical models applied to digestion kinetics has been widely applied to provide prediction of animal performance, maximize the use of nutrients and reduce nutritional losses due to excreta and a reduction in the cost of animal production. In this context, it aimed to conduct a literature review on the use of mathematical models and to analyze comparisons of different models to predict ruminal digestion. The in vitro gas production technique provides direct measurement of the ruminal digestion rate associated with gas production and the respective gravimetric measurement of the food or diet under test. Nonlinear models are chosen to evaluate ruminal digestion due to a better interpretation of biological parameters, they produce exponential and sigmoidal growth equations. However, the most suitable model for evaluation depends on the type of food or diet. The two-compartment logistical model presents a better adjustment of the gas production curve, mainly for foods with a high proportion of fiber. Among this, single-compartment models can be well applied to evaluate the degradation kinetics of foods with low fibrous carbohydrate content. Therefore, the choice of the most appropriate model is up to the researcher to assess which model best suits the chemical-chemical composition of the food or diet.

Automated Census Population Projection and Data Management System

Population census data has become more pervasive to lives which has demanded for increase in scope, completeness, accuracy and validity, and improve on their national value and international comparability. The accuracy of population projections has been attracting more attention, driven by concerns about the possible long-term effects of aging and other demographic trends. This paper therefore, attempt to improve on the manual way of managing census data by developing an automated census data management system. This system in addition, is capable of projecting population growth using exponential growth equation. The National Population Commission, Benin City was used as a case study.

Impact of COVID-19 epidemic curtailment strategies in selected Indian states: An analysis by reproduction number and doubling time with incidence modelling.

The Government of India in-network with the state governments has implemented the epidemic curtailment strategies inclusive of case-isolation, quarantine and lockdown in response to ongoing novel coronavirus (COVID-19) outbreak. In this manuscript, we attempt to estimate the impact of these steps across ten selected Indian states using crowd-sourced data. The trajectory of the outbreak was parameterized by the reproduction number (R0), doubling time, and growth rate. These parameters were estimated at two time-periods after the enforcement of the lockdown on 24th March 2020, i.e. 15 days into lockdown and 30 days into lockdown. The authors used a crowd sourced database which is available in the public domain. After preparing the data for analysis, R0 was estimated using maximum likelihood (ML) method which is based on the expectation minimum algorithm where the distribution probability of secondary cases is maximized using the serial interval discretization. The doubling time and growth rate were estimated by the natural log transformation of the exponential growth equation. The overall analysis shows decreasing trends in time-varying reproduction numbers (R(t)) and growth rate (with a few exceptions) and increasing trends in doubling time. The curtailment strategies employed by the Indian government seem to be effective in reducing the transmission parameters of the COVID-19 epidemic. The estimated R(t) are still above the threshold of 1, and the resultant absolute case numbers show an increase with time. Future curtailment and mitigation strategies thus may take into account these findings while formulating further course of action.

Effect of specimen processing, growth supplement, and different metabolic population on Mycobacterium tuberculosis laboratory diagnosis.

IntroductionSputum specimen decontamination steps are essential due to the presence of other saprophytic and infectious organisms. However, they negatively affect the mycobacterial recovery. In addition, little is known about the Mycobacterium tuberculosis killing efficacy of the PANTA (polymyxin-B, amphotericin-B, nalidixic acid, trimethoprim, azilocillin) antibiotics. Moreover, M. tuberculosis can be present in more than one metabolic population, but the effect of different growth characteristics on the mycobacterial growth indicator tube (MGIT) based time-to-positive (TTP) is not well studied.MethodsWe performed—(1) experiments using the solid agar and MGIT method to determine the effect of the NALC-NaOH decontamination method, (2) concentration-response studies with each individual antibiotic in the PANTA, and (3) the effect of the M. tuberculosis metabolic population on the TTP. TTP was recorded using the Epicenter software and exponential growth equation was used to calculate the doubling time of the bacteria, whereas, CFU/mL was analyzed using the Inhibitory Sigmoid Emax model for each antibiotic.ResultsDecontamination resulted in 4.36+0.13 log10 CFU/mL difference in cultures treated with NALC-NaOH versus no decontamination process and the limit of detection decreased from 1.47 log10 CFU/mL to the 0.42 log10 CFU/mL following NALC-NaOH treatment. PANTA at currently used antibiotic concentrations, did not had negative effect on mycobacterial recovery. Exponential growth model estimated doubling time for the log-phase growth M. tuberculosis as 2.04 days, for the semi-dormant bacilli as 2.80 days, and 6.37 days for the anaerobic cultures.ConclusionSpecimen decontamination method negatively affect the laboratory diagnosis of M. tuberculosis, polymyxin-B and nalidixic acid have anti-tuberculosis efficacy at high concentrations, and the doubling time of different metabolic population should be considered when deciding the time-in-protocol for the MGIT system.

Monitoring of a long term phytoremediation process of a soil contaminated by heavy metals and hydrocarbons in Tuscany.

The purpose of this study was to monitor and model indicators of soil contamination, organic matter evolution and biochemical processes involved in a long-term phytoremediation process. Populus nigra L., Paulownia tomentosa Steud., Cytisus scoparius L. and natural vegetation were used in differently contaminated areas (high, medium and low levels of contamination). Parameters indicating contamination (total petroleum hydrocarbons (TPH) and heavy metals) and agronomic (C, N and P) and functional (enzyme activities) soil recovery were monitored for 3.5 years. Three subareas with different levels of contamination (high, medium and low) were identified according to the Nemerow Index. A considerable decrease in TPH (52% on average) over time in the whole site was measured, while the metal reduction was only of about 22% at surface level. A stimulation in metabolic soil processes and improvement in the chemical quality of the soil was also observed throughout the experimental site. Statistical analysis modelling showed that the contaminant content decreased following a one-phase decay model, while the dramatic increase in enzyme activities could be represented by an exponential growth equation. On the basis of our data, it is possible to conclude that the initial contamination level affected neither the decontamination process nor the improvement in soil quality, which occurred similarly in the three different contaminated areas.

Saccharomyces cerevisiae Exponential Growth Kinetics in Batch Culture to Analyze Respiratory and Fermentative Metabolism.

Saccharomyces cerevisiae cells in the exponential phase sustain their growth by producing ATP through fermentation and/or mitochondrial respiration. The fermentable carbon concentration mainly governs how the yeast cells generate ATP; thus, the variation in fermentable carbohydrate levels drives the energetic metabolism of S. cerevisiae. This paper describes a high-throughput method based on exponential yeast growth to estimate the effects of concentration changes and nature of the carbon source on respiratory and fermentative metabolism. The growth of S. cerevisiae is measured in a microplate or shaken conical flask by determining the optical density (OD) at 600 nm. Then, a growth curve is built by plotting OD versus time, which allows identification and selection of the exponential phase, and is fitted with the exponential growth equation to obtain kinetic parameters. Low specific growth rates with higher doubling times generally represent a respiratory growth. Conversely, higher specific growth rates with lower doubling times indicate fermentative growth. Threshold values of doubling time and specific growth rate are estimated using well-known respiratory or fermentative conditions, such as non-fermentable carbon sources or higher concentrations of fermentable sugars. This is obtained for each specific strain. Finally, the calculated kinetic parameters are compared with the threshold values to establish whether the yeast shows fermentative and/or respiratory growth. The advantage of this method is its relative simplicity for understanding the effects of a substance/compound on fermentative or respiratory metabolism. It is important to highlight that growth is an intricate and complex biological process; therefore, preliminary data from this method must be corroborated by the quantification of oxygen consumption and accumulation of fermentation byproducts. Thereby, this technique can be used as a preliminary screening of compounds/substances that may disturb or enhance fermentative or respiratory metabolism.

Predictable tendency of Bi NIR emission in Bi‐doped magnesium aluminosilicate laser glasses

AbstractBecause of superbroad luminescence in the range of near infrared (NIR), Bi‐doped glasses and fibers have received more attentions recently for the applications in super broadband optical fiber amplifiers or new wavelength lasers. As the luminescence comes from the transitions between naked 6p orbitals of bismuth, it is very susceptible to slight changes of local field around Bi. Therefore, it is always very challenging to predict NIR emission of bismuth in advance. Here, we found bismuth NIR emission shows predictable tendency in ternary glass system of MgO–Al2O3–SiO2. The emission peak shifts red along the content of magnesium upon the excitation of 484 nm, which follows a single exponential growth equation. In the meantime, the full width at half maximum (FWHM) is broadened while the lifetime keeps decreasing. Glass structure analysis on basis of FTIR, 27Al NMR, 29Si NMR spectra reveals that these changes correlate to integrity of glass network, the increased disorder of local field around bismuth and the enhanced interaction between bismuth and host, which are perhaps due to the linear increase of nonbridging oxygen, and the enhanced Si–O asymmetric stretching vibrations along with magnesium, respectively. Electron probe microanalysis shows good homogeneity of Si, Al, Mg, Bi, and O distribution within the samples, and yoyo experiments of heating and cooling between 30°C and 300°C reveal the good resistance of such doped glasses to thermal degradation. This makes the glasses promising in applications of fiber devices even under extreme condition such as at higher temperature. The finding in this work should be helpful for the design of Bi‐doped laser glasses in future.

Comparative analysis of the fatigue short crack growth on Al 6061-T6 alloy by the exponential crack growth equation and a proposed empirical model

In this work, the short crack propagation and growth rate nonlinear behavior of an Al 6061 alloy in T6 condition, were assessed. The specimens were fatigue tested at 20Hz in a rotating bending fatigue machine with constant amplitude loading of 88%, 61% and 38% of yield strength, and the short crack initiation and propagation were followed up using optical microscopy. The interaction between the surface cracks and aluminium microstructure were identified: persistent slip marks (PSMs) can be observed on the surface specimen, where persistent slip bands (PSBs) emerge from the surface as a result of accumulated damage by intrusion-extrusion mechanism, which eventually leads to the accumulation of dislocations within the grain as a consequence of grain border barriers and stress concentration at second phase particles. The recorded length crack paths were later analyzed to study the crack growth using the Frost and Dugdale exponential crack growth equation (ECG) and its comparison with a proposed model (PM) developed by multiple linear regression. The results showed that the crack growth rate is affected by microstructural features in the early growth stage, which is assumed to be from the nucleation up to 150µm of crack length. The ECG is reliable only for the stage where the crack growth is mainly a consequence of stress concentration at crack tip; in contrast, the PM do properly describes the nonlinearity behavior between short and long crack growth.

On the USAF ‘risk of failure’ approach and its applicability to composite repairs to metal airframes

The USAF report on the risk analysis of aging aircraft fleets notes that the operational life of individual airframes is seldom equal to the design life of the fleet and that the life of an aircraft fleet tends to be determined more by its inherent operational capability and maintenance costs rather than by the number of flight hours specified at the design stage. As such this paper focuses on whether the USAF approach to risk assessment can be used for airframes repaired with a composite patch/doubler. To this end the present paper describes a test program designed to study the effect of adhesively-bonded composite repairs to fatigue cracks that, prior to repair, have grown from small naturally-occurring materials discontinuities. This study reveals that crack growth in composite repairs conforms to the exponential growth equation used in the USAF approach to assessing the risk of failure. Furthermore, the exponent, ω, in the exponential growth law can be determined from the crack growth history associated with the unrepaired specimens and the simple reduction in the stress due to the application of the composite patch/doubler, using the ‘cubic rule’ that was previously used to assess crack growth in the RAAF F/A-18 (Hornet) fleet.

Carbon sequestration dynamic, trend and efficiency as affected by 22‐year fertilization under a rice–wheat cropping system

AbstractThe maintenance and accumulation of soil organic carbon (SOC) in agricultural systems is critical to food security and climate change, but information about the dynamic trend and efficiency of SOC sequestration is still limited, particularly under long‐term fertilizations. In a typical Purpli‐Udic Cambosols soil under subtropical monsoon climate in southwestern China this study thus estimated the dynamic, trend and efficiency of SOC sequestration after 22‐year (1991–2013) long‐term inorganic and/or organic fertilizations. Nine fertilizations under a rice–wheat system were examined: control (no fertilization), N, NP, NK, PK, NPK, NPKM (NPK plus manure), NPKS (NPK plus straw), and 1.5NPKS (150% NPK plus straw). Averagely, after 22‐years SOC contents were significantly increased by 4.2–25.3% and 10.2–32.5% under these fertilizations than under control conditions with the greatest increase under NPKS. The simulation of SOC dynamic change with an exponential growth equation to maximum over the whole fertilization period predicted the SOC level in a steady state as 18.1 g kg−1 for NPKS, 17.4 g kg−1 for 1.5NPKS, and 14.5–14.9 g kg−1 for NK, NP, NPK, and NPKM, respectively. Either inorganic, organic or their combined fertilization significantly increased crop productivity and C inputs that were incorporated into soil ranging from 0.91 to 4.63 t (ha · y)−1. The C sequestration efficiency was lower under NPKM, NPKS, and 1.5NPKS (13.2%, 9.0%, and 10.1%) than under NP and NPK (17.0% and 14.4%). The increase of SOC was asymptotical to a maximum with increasing C inputs that were variedly enhanced by different fertilizations, indicating an existence of SOC saturation and a declined marginal efficiency of SOC sequestration. Taken all these results together, the combined NPK plus straw return is a suitable fertilizer management strategy to simultaneously achieve high crop productivity and soil C sequestration potential particularly in crop rotation systems.

Deriving Population Growth Models by Growing Fruit Fly Colonies

Population growth presents a unique opportunity to make the connection between mathematical and biological reasoning. The objective of this article is to introduce a method of teaching population growth that allows students to utilize mathematical reasoning to derive population growth models from authentic populations through active learning and firsthand experiences. To accomplish this, we designed a lab in which students grow and count populations of Drosophila over the course of 12 weeks, modifying abiotic and biotic limiting factors. Using the data, students derive exponential and logistic growth equations, through mathematical reasoning patterns that allow them to understand the purpose of these models, and hypothesize relationships between various factors and population growth. We gathered student attitudinal data and found that students perceived the lab as more effective, better at preparing them for lecture, and more engaging than the previous lab used. Through this active and inquiry-based method of teaching, students are more involved and engaged in both mathematical and biological reasoning processes.

Retrospective growth kinetics and radiosensitivity analysis of various human xenograft models.

The purpose of this study was to delineate the various factors that affect the growth characteristics of human cancer xenografts in nude mice and to reveal the relationship between the growth characteristics and radiosensitivity. We retrospectively analyzed 390 xenografts comprising nine different human cancer lines grown in nude mice used in our institute between 2009 and 2015. Tumor growth rate (TGR) was calculated using exponential growth equations. The relationship between the TGR of xenografts and the proliferation of the cells in vitro was examined. Additionally, we examined the correlations between the surviving fractions of cells after 2 Gy irradiation in vitro and the response of the xenograft to radiation. The TGR of xenografts was positively related to the proliferation of the cells in vitro (rP=0.9714, p<0.0001), whereas it was independent of the histological type of the xenografts. Radiation-induced suppression of the growth rate (T/C%) of xenografts was positively related to the radiosensitivity of the cells in vitro (SF2; rP=0.8684, p=0.0284) and TGR (rP=0.7623, p=0.0780). The proliferation of human cancer cells in vitro and the growth rate of xenografts were positively related. The radiosensitivity of cancer cells, as judged from the SF2 values in vitro, and the radiation-induced suppression of xenograft growth were positively related. In conclusion, the growth rate of human xenografts was independent of histological type and origin of the cancer cells, and was positively related to the proliferation of the cancer cells in vitro.

Age, growth, and recruitment patterns of juvenile ladyfish (Elops sp) from the east coast of Florida (USA).

Ladyfish (Elops sp) are a common and economically valuable coastal nearshore species found along coastal beaches, bays, and estuaries of the southeastern United States, and subtropical and tropical regions worldwide. Previously, ladyfish were a substantial bycatch in Florida’s commercial fisheries, but changes in regulations significantly reduced commercial landings. Today, ladyfish are still taken in commercial fisheries in Florida, but many are also taken by recreational anglers. Life-history information and research interest in ladyfish is almost non-existent, especially information on age and growth. Thus, the overarching purpose of this study was to expand our understanding of ladyfish age and growth characteristics. The specific objectives were to describe, for the first time, age, growth, and recruitment patterns of juvenile ladyfish from the east coast of Florida (USA). In the Indian River Lagoon (IRL), annual monthly length-frequency distributions were confounded because a few small individuals recruited throughout the year; monthly length-frequency data generally demonstrated a cyclical pattern. The smallest were collected in September and the largest in May. Post-hoc analysis showed no significant difference in length between August and May, or among the other months. In Volusia County (VC), annual monthly length-frequency distribution demonstrated growth generally occurred from late-winter and spring to summer. The smallest ladyfish were collected in February and the largest in August. On average, the absolute growth rate in the IRL was 36.3 mm in 60 days or 0.605 mm day−1. Cohort-specific daily growth rates, elevations, and coincidentals were similar among sampling years. Cohort-specific growth rates ranged from 1.807 in 1993 to 1.811 mm day−1 in 1994. Overall, growth was best (i.e., goodness of fit) described by exponential regression. On average, the absolute growth rate in VC was 28 mm in 150 days or 0.1866 mm day−1. Cohort-specific daily growth rates were significantly different among sampling years; however, the elevations and coincidentals were similar. Cohort-specific growth rates ranged from 1.741 in 1994 to 1.933 mm day−1 in 1993. Mean ladyfish growth was best described by linear regression; however, natural growth was explained better by exponential regression. In the IRL, the corrected exponential growth equation yielded a size-at-age 1 of 156.0 mm SL, which corresponded to an estimated growth rate of 0.4356 mm day−1. In VC, the corrected exponential growth equation yielded a size-at-age 1 of 80 mm SL corresponding to an estimated growth rate of 0.2361 mm day−1.