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ABSTRACT: The present study aimed to compare the dynamics of growth of various chicken genotypes exposed to heat stress, low-input diets, and free-range farming by using Gompertz model to gain insights into their capabilities to face environmental and nutritional challenges. Three in vivo trials (T1: heat stress, T2: low-input diets, and T3: free-range system) were conducted, involving a total of 671 animals. Five chicken genotypes were employed in each trial: 2 Italian local breeds, Bionda Piemontese (BP) and Robusta Maculata (RM), along with their crossbreeds with Sasso hens (BP×SA and RM×SA), and a commercial hybrid (Ross 308). One-day-old male chicks were individually identified, and the 5 genotypes were randomly allocated to different challenging conditions: T1 involved 2 environmental temperatures (thermoneutral vs. high temperature); T2 involved 2 diets (standard vs. low-input); T3 involved 2 rearing systems (conventional vs. free-range). The chickens were weighed once a week from their arrival until slaughtering, and the data were used to build growth curves using the Gompertz model. Chickens from different genotypes were slaughtered at varying ages based on their maturity. In all trials, the challenging conditions significantly reduced adult body weight (A; −31.0%) and maximum growth rate (MGR; −25.6%) of Ross chickens. In contrast, in T1 and T2, no significant changes were observed in the main growth curve parameters of local breeds and crossbreeds, while under free-range conditions, there was even an increase in the A and MGR of these genotypes. The crossbreeding was effective in increasing A and MGR of BP (+30.5% in BP×SA), as well as in improving the precocity and MGR of RM (+19.5% in RM×SA). Our findings highlight the effectiveness of the Gompertz model as a tool for evaluating birds’ adaptability and confirm the greater ability of local breeds and crossbreeds to adapt to different challenges. In conclusion, our methodological approach could be used to choose the genotype most suited to the environmental context and confirm the potential advantages of crossbreeding for enhancing resilience and sustainability.

The aim of this paper is to perform a State wise Analysis of the First and the Second COVID- 19 Waves experienced by India using the Gompertz Curves and to estimate the maximum number of affected individuals for each wave with the best possible accuracy. A total of 21 large States are chosen for the analysis encompassing 97% of the Indian population. Data on cumulative number of cases is available till 31st October 2021. The entire dataset is segregated into two parts, i.e., the First and the Second Waves and then modelled individually by the Gompertz Curves with some generalizations. The predicted maximum cumulative numbers of COVID-19 affected individuals are found to be quite accurate. Besides, it is found to be possible to give a methodology how one can predict these numbers with a much smaller dataset. This is important as it can help the authorities in taking an informed decision on the efficient allocation of the limited health care resources.

Vehicle ownership forecasting models based on the Gompertz curve generally employ per capita Gross Domestic Product as the primary explanatory variable. The γ coefficients in the curves specify the ultimate vehicle saturation level and α, β the profile of the S-curve shape. The γ coefficient is assumed to be the single universal value that all countries will eventually reach. The present research hypothesised that countries could have variable saturation levels and, as such, the γ coefficient would not be a universal constant. On that premise, it attempted modelling the γ coefficient as a function of several other extraneous factors that significantly influence a country’s vehicle ownership and ultimately its saturation level, thus resulting in a country-specific γ; the application of the Gompertz model and the relationship of vehicle ownership would then be influenced by the country-specific characteristics. It was found that, while vehicle ownership is influenced by the GDP as in the case of Gompertz model, the country-specific γ would also be influenced by other identifiable variables such as household size, population density, share of public transport, and percentage of female drivers in each country. The results confirm the globally observable phenomenon that high-income countries do not converge to a universal vehicle ownership saturation level. Singapore and Hong Kong are examples, usually excluded from the Gompertz model, which can now be explained by the new model.

The present study aimed to compare the dynamics of growth of various chicken genotypes exposed to heat stress, low-input diets, and free-range farming by using Gompertz model to gain insights into their capabilities to face environmental and nutritional challenges. Three in vivo trials (T1 : heat stress, T2 : low-input diets, and T3 : free-range system) were conducted, involving a total of 671 animals. Five chicken genotypes were employed in each trial: 2 Italian local breeds, Bionda Piemontese (BP) and Robusta Maculata (RM), along with their crossbreeds with Sasso hens (BP×SA and RM×SA), and a commercial hybrid (Ross 308). One-day-old male chicks were individually identified, and the 5 genotypes were randomly allocated to different challenging conditions: T1 involved 2 environmental temperatures (thermoneutral vs. high temperature); T2 involved 2 diets (standard vs. low-input); T3 involved 2 rearing systems (conventional vs. free-range). The chickens were weighed once a week from their arrival until slaughtering, and the data were used to build growth curves using the Gompertz model. Chickens from different genotypes were slaughtered at varying ages based on their maturity. In all trials, the challenging conditions significantly reduced adult body weight (A ; −31.0%) and maximum growth rate (MGR ; −25.6%) of Ross chickens. In contrast, in T1 and T2, no significant changes were observed in the main growth curve parameters of local breeds and crossbreeds, while under free-range conditions, there was even an increase in the A and MGR of these genotypes. The crossbreeding was effective in increasing A and MGR of BP (+30.5% in BP×SA), as well as in improving the precocity and MGR of RM (+19.5% in RM×SA). Our findings highlight the effectiveness of the Gompertz model as a tool for evaluating birds' adaptability and confirm the greater ability of local breeds and crossbreeds to adapt to different challenges. In conclusion, our methodological approach could be used to choose the genotype most suited to the environmental context and confirm the potential advantages of crossbreeding for enhancing resilience and sustainability. [ABSTRACT FROM AUTHOR]

Curvilinear growth trajectories of products/services are common in the tourism and hospitality industry. To fit nonlinear growth patterns with multilevel structures, this study proposed Bayesian hierarchical growth curve models (BHGCMs) in line with the increasing adoption of Bayesian analysis in tourism and hospitality academia. We provided the basic form of BHGCM along with its unique advantages. For an empirical test, this study applied several growth curves to approximate online reviews of U.S. hotels from August 2020 to January 2021. After selecting a Gompertz curve as a mean function of the GCM, a Bayesian hierarchical approach was employed to estimate growth parameters—namely, base and maximum volume of hotel reviews, inflection week, and relative growth rate—and identify their determinants. Our findings demonstrate the superiority of the proposed BHGCM in fitting the growth patterns of hotel reviews while revealing the effect of price and accumulated reviews on the parameters. • We proposed a Bayesian hierarchical growth curve model (BHGCM) to fit curvilinear growth patterns. • In comparison with growth models, the advantages of BHGCM were discussed. • To find the best fitted BHGCM, different growth curve functions were compared. • An empirical test validated the outperformance of the proposed BHGCM in fitting growth curves of hotel reviews. • We also identified the determinants of four growth model parameters. [ABSTRACT FROM AUTHOR]

The paper explores the economic opportunities of growing fast-growing plants for bioenergy production and use. Based on primary data of the above-ground dry biomass of the Miscanthus × giganteus, from the experimental field of Kolíňany, the average yield during the life cycle of the crop was 33.31 t/ha (stand. dev. 7.07). The next step was assembling the economic model of gross financial yield based on using the biomass for the production of bioenergy. Using the Discounted Cash-flow model, the gross financial yield, neglecting the costs, was set to 1547 €/ha. Finally, adjusting for the growing conditions of the Miscanthus, we set the gross financial yield as a deferred annuity to 3036.93 €/ha per one life cycle of the crop.

The use of control strategies for the biological process of hydrogen (H 2) production can increase productivity, stability, and robustness, increasing the viability of the implementation of these systems at the industrial level. A feedback control strategy for optimizing biohydrogen production from organic solid waste in a discontinuous process was proposed and pragmatically tested. The control strategy, which is based on recursively fitting a modified Gompertz model to gathered online data of the cumulative H 2 volume, could eventually stabilize the system at an optimal reaction time. The control strategy was evaluated during 140 degradation cycles maintaining a stable H 2 production with a reproducible form in the cumulative H 2 production curve. Independent of the changes in the microbial population dynamics in the reactor, the control strategy maintained a stable H 2 production avoiding the presence of methanogenic archaea. With the proposed controller, a compromise between the needed HRT and the H 2 production was obtained. • A feedback control strategy for H 2 production was proposed and validated. • The control maintained stable and reproducible bioH 2 production. • A compromise between the needed HRT and the bioH 2 production was obtained. [ABSTRACT FROM AUTHOR]

This article shows how new time series models can be used to track the progress of an epidemic, forecast key variables and evaluate the effects of policies. The univariate framework of Harvey and Kattuman (2020, Harvard Data Science Review, Special Issue 1—COVID-19, https://hdsr.mitpress.mit.edu/pub/ozgjx0yn) is extended to model the relationship between two or more series and the role of common trends is discussed. Data on daily deaths from COVID-19 in Italy and the UK provides an example of leading indicators when there is a balanced growth. When growth is not balanced, the model can be extended by including a non-stationary component in one of the series. The viability of this model is investigated by examining the relationship between new cases and deaths in the Florida second wave of summer 2020. The balanced growth framework is then used as the basis for policy evaluation by showing how some variables can serve as control groups for a target variable. This approach is used to investigate the consequences of Sweden's soft lockdown coronavirus policy in the spring of 2020. [ABSTRACT FROM AUTHOR]

Growth rate is a major component of feed efficiency when estimating residual feed intake (RFI). Quantile regression (QR) methodology can be used to identify animals with different growth trajectories. The objective of this study was to evaluate the use of QR to identify phenotypic and genetic differences in pigs selected for low RFI. Using performance data on 750 Yorkshire pigs selected for low RFI, individual average daily gain (ADG), average daily feed intake (ADFI), RFI and Gompertz growth curve parameters (asymptotic weight (a), inflection point (b) and decay parameter (c)) were estimated for each pig. Using QR methodology, three Gompertz growth curves were estimated for the whole population for three quantiles (0.1, 0.5 and 0.9) of the BW data. Each animal was classified into one of the quantile regression groups (QRG) based on their overall Euclidian distance between each observed and estimated BW from the quantile growth curves. These three curves were also estimated using only part of the data (generations −1 to 3, and −1 to 4) in order to evaluate the agreement classification rate of animals from later generations into QRGs. We evaluated the effect of QRG on growth parameters and performance traits. Genetic parameters were estimated for these traits, as well as for QRG. In addition, genetic trends for each QRG were estimated. Three distinct growth curves were observed for animals classified into either quantiles 0.1 (QRG0.1), 0.5 (QRG0.5) or 0.9 (QRG0.9). When only part of the data was used to estimate quantile growth curves, all animals from QRG0.1 were correctly classified in their group. Animals in QRG0.1 had significantly lower ADFI, ADG and RFI, and greater a, b and c than animals in the other groups. Quantile regression groups analysed as a trait was highly heritable (0.41) and had high (0.8) and moderate (0.46) genetic correlations with ADG and RFI, respectively. Selection for reduced RFI increased the number of animals classified as QRG0.1 in the population. Overall, downward genetic trends were observed for all traits as a function of selection for reduced RFI. However, QRG0.1 was the only group that had a positive genetic trend for ADG. Altogether, these results indicate that selection for reduced RFI changes the shape of growth curves in Yorkshire in pigs, and that QR methodology was able to identify animals having different genetic potential for feed efficiency, bringing a new opportunity to improve selection for reduced RFI.

In recent years, the influence of earthquake on geotechnical engineering has been paid more and more attention, and the study of soil dynamic characteristics is the most important part. In order to reveal the dynamic characteristics of the silty clay in the reservoir area of the hydropower station, firstly many samples are taken for dry-wet cycle several times to simulate the changes of soil in the reservoir slope under the condition of reservoir water level change or rainfall evaporation. And then dynamic triaxial tests are carried out on those samples to determine the dynamic deformation development law of the soil. The model is established based on Gompertz curve, making it be applied to the deformation curve of soil dynamics. The dynamic deformation curve of samples after different times of dry-wet cycle is fitted. The error of fitting value and actual value is within 5 %, and the relationship between vibration frequency and dynamic strain is established. The research results have practical significance for the prediction of dynamic deformation of soil and the application of Gompertz curve. [ABSTRACT FROM AUTHOR]

Induction and proliferation of cancer cells are complex processes whose ab initio mathematical description is virtually impossible. Nevertheless, some integral characteristics such as the Gompertz law, which is generally used to describe cancer development, can result from a simple mathematical consideration of biophysical processes. The simplified response to a single-source lesion created in a cell's DNA consists in the repair of the lesion or induction of a mutation which can lead to neoplastic transformation. This approach makes it possible to propose a single mathematical formula connecting the Gompertz curve with the simplified biophysical characteristics of tumor growth. Such an approach, which merges the process of neoplastic transformation with cancer development, is shown in the present paper based on the relatively simple analytical and Monte-Carlo models. The models operate with a small number of biophysical parameters and account, at least in part, for the mechanisms that operate in an organism exposed to low doses of ionizing radiation. [ABSTRACT FROM AUTHOR]

In traditional calculating median, mean and sorting of grain-size distribution (GSD) by Folk and Ward (1957), graphing cumulative probability curves and estimating grain-sizes are tedious and slow for vast samples. Taking 88 samples of cores in Well Y1 in Gasikule Oilfield, Qaidam Basin, as the primary material, a new approach to calculate these three parameters is proposed in this paper, which is based on sigmoidal Gompertz curve and Folk-Ward Formula. Establishing Gompertz curve to fit cumulative probability values is the first stage. Solving the coefficients of Gompertz curve using least-squares algorithm is the second stage. Calculating median, mean and sorting of GSD by Gompertz inverse function in Folk-Ward Formula is the third stage. Coefficient of determination between fitted and laboratorial cumulative probability values are ranged from 0.994 to 1, and that of frequency values are larger than 0.565. The coefficients of determination of calculated and laboratorial median, mean and sorting of 88 samples are 0.9960, 0.9943 and 0.5416 respectively. The results demonstrate that the proposed method is feasible and effective to fit the cumulative probability values of GSD, and calculate median and mean in Folk-Ward Formula. [ABSTRACT FROM AUTHOR]

Bioturbation by the sand dollar Scaphechinus griseus is suspected to inhibit the recruitment of Pseudocardium sachalinense, a commercially important bivalve. This study aimed to develop a standard method for the extermination of the sand dollar by examining its reproductive cycle, relationships between age and growth, and population structure in Tomakomai, southwest Hokkaido, Japan. Histological observations of the gonads indicated that the sand dollar has one spawning season per year, in June–August. Seasonal changes in the appearance of a dark band around the interambulacral plate suggested that the annual ring primarily forms in June–July, with the first ring forming at 1 year of age. Analysis of fitness by growth models showed that the Gompertz curve was better matched to the data than the von Bertalanffy and logistic curves; growth is fast until 1.6 years of age, then slows. The population density was 190–257 individuals/m2, and average test diameters were 39.0–40.9 mm. Three-year-olds comprised the highest percentage of the population; no individuals of 8 years of age or older were detected. In conclusion, to reduce the density of sand dollars efficiently and to prevent their reproduction, individuals with a test diameter of over 30 mm should be exterminated before the spawning season. [ABSTRACT FROM AUTHOR]

Growth rate is a major component of feed efficiency when estimating residual feed intake (RFI). Quantile regression (QR) methodology can be used to identify animals with different growth trajectories. The objective of this study was to evaluate the use of QR to identify phenotypic and genetic differences in pigs selected for low RFI. Using performance data on 750 Yorkshire pigs selected for low RFI, individual average daily gain (ADG), average daily feed intake (ADFI), RFI and Gompertz growth curve parameters (asymptotic weight (a), inflection point (b) and decay parameter (c)) were estimated for each pig. Using QR methodology, three Gompertz growth curves were estimated for the whole population for three quantiles (0.1, 0.5 and 0.9) of the BW data. Each animal was classified into one of the quantile regression groups (QRG) based on their overall Euclidian distance between each observed and estimated BW from the quantile growth curves. These three curves were also estimated using only part of the data (generations −1 to 3, and −1 to 4) in order to evaluate the agreement classification rate of animals from later generations into QRGs. We evaluated the effect of QRG on growth parameters and performance traits. Genetic parameters were estimated for these traits, as well as for QRG. In addition, genetic trends for each QRG were estimated. Three distinct growth curves were observed for animals classified into either quantiles 0.1 (QRG0.1), 0.5 (QRG0.5) or 0.9 (QRG0.9). When only part of the data was used to estimate quantile growth curves, all animals from QRG0.1 were correctly classified in their group. Animals in QRG0.1 had significantly lower ADFI, ADG and RFI, and greater a, b and c than animals in the other groups. Quantile regression groups analysed as a trait was highly heritable (0.41) and had high (0.8) and moderate (0.46) genetic correlations with ADG and RFI, respectively. Selection for reduced RFI increased the number of animals classified as QRG0.1 in the population. Overall, downward genetic trends were observed for all traits as a function of selection for reduced RFI. However, QRG0.1 was the only group that had a positive genetic trend for ADG. Altogether, these results indicate that selection for reduced RFI changes the shape of growth curves in Yorkshire in pigs, and that QR methodology was able to identify animals having different genetic potential for feed efficiency, bringing a new opportunity to improve selection for reduced RFI. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has highlighted the need for finding mathematical models to forecast the evolution of the contagious disease and evaluate the success of particular policies in reducing infections. In this work, we perform Bayesian inference for a non-homogeneous Poisson process with an intensity function based on the Gompertz curve. We discuss the prior distribution of the parameter and we generate samples from the posterior distribution by using Markov Chain Monte Carlo (MCMC) methods. Finally, we illustrate our method analyzing real data associated with COVID-19 in a specific region located at the south of Spain.

The Gompertz method is used to analyze the growing glioblastoma data and estimate how accurate the results of growth over time are. The Gompertz curve is expressed as V(t) = αe-βe-γt. The data from the tumor is graphed in Excel along with the values from the Gompertz equation. Excel solver is used to assist in determining the constant values of α, β, and γ. The data of the tumor is overall very close to the outcome of the Gompertz model following a sigmoidal “S” curve.

ABSTRACT The objective of this study was to determine the adjustment quality of non-linear models and estimate the growth parameters and body chemical composition of a meat-type quail strain (Coturnix coturnix coturnix) and two laying quail strains (Coturnix coturnix japonica), designated yellow and red. The study used 1500 quail, not sexed, distributed in a completely randomized design with three treatments and five repetitions. The experimental period was from 1-42 days of age. The birds were raised in a conventional system and fed ad libitum with a diet formulated to meet their nutritional requirements. Quail were weighed weekly, and a representative sample was slaughtered to evaluate their body chemical composition. The adjustment quality of the models was evaluated by means of the residual mean square (RMS), regression residue squares sum (SSRR), and number of iterations required for convergence. In evaluating the adjustment quality for the body weight of the three strains, the Gompertz, Logistic, and Von Bertalanffy models gave good fit, with Gompertz providing the best adjustment among them. For body composition, the Gompertz and Logistic models were the best, with Gompertz showing a slight superiority. Gompertz is the best model for describing growth curves and body chemical composition of body weight, protein, water, and ash in meat-type quail. In addition, it is the best model for describing growth curves and body chemical composition of body weight of yellow laying quail and of body weight, protein, and ash in red laying quail. Logistic was the best model for describing growth curves and body chemical composition of water, protein, and ash in yellow laying quail, and of water in red laying quail.

Role of tumor-suppressor genes in the life longevity has not been studied in detail. The purpose of the current work is to study the influence of heterozygous tumor suppressors on the life span of drosophila. We show that heterozygotes for l(3)hem, hyd, gd, ex or ft, both females and males, have a shorter life. The analysis of Gompertz curve parameters indicates that the l(3)hem, hyd or gd mutations increase age-related parameter (α) in males, while gd mutation increases the death background parameter (R) and the ex agerelated parameter in females. The effects of the mutations on the life span are probably associated with hedgehog (hyd), Notch (gd) и Hippo (ex и ft) signal transduction pathways.

The main objective of this work is to study the existence of a possible dependence between different individuals of the same species of Mediterranean shrubs, in particular Ulex parviflorus Pourret , located on an area of 100 m 2 in the Desert of Las Palmas (Benicassim, Castellón, Spain). The possible correlation between them is limited to the temporal and spatial dependence, that is to say, to identify if the individuals have statistically significant growth curves, and in the case of being, to see if there is a correlation of the individuals located with proximity in the space. The characteristics (variables) studied are the height and diameter of the Ulex parviflorus , and one data per week is available for a period of two years. At the same time, the coordinates (x, y) within the study region for each individual of the species studied are also available. The conclusion is that the spatial pattern of the Ulex parviflorus is not random but is governed by some biological mechanism that provides a structure of inhibition at small distances combining a certain aggregation structure at distances between 3 and 4 m. [ABSTRACT FROM AUTHOR]

The objectives of the present study were to determine the parameters of Gompertz equations and to determine curves and growth rate, feed intake and body component deposition, as well as allometric coefficients of body water, protein, and fat relative to live weight of male and female broilers of intermediate performance (C44) and high performance (Cobb-500) genetic strains. In total, 384 one-d-old chicks were distributed into four treatments: male Cobb 500, male C44, female Cobb 500, and female C44, with six replicates of 16 birds, according to a completely randomized experimental design. Average body weight, weight gain, and feed intake were weekly determined, and six birds, representing the average weight of each treatment, were sacrificed to determine body composition. Growth curves were built applying Gompertz function, with excellent fit, and growth, feed intake, and tissue deposition rates were obtained by its derivatives. Superior growth rate was obtained for Cobb 500 male broilers. This genetic strain has higher feed intake capacity, which is achieved earlier than in the C44 strain. Protein and fat deposition maturity was reached earlier in males than in females in Cobb 500. The allometric coefficients showed earlier maturity for body water in C44 and females. In terms of body protein, male Cobb 500 broilers reached maturity earlier than females and C44. Body fat deposition maturity was reached earlier in Cobb 500 than in C44. The Gompertz equations obtained in the present study efficiently described body growth, feed intake, and deposition of body components, with a coefficient of determination higher than 0.99.

In this paper we present a simple mathematical model of cancer growth. The model is discrete, it is a linear map ( T) on three dimensional Eucledian vector space. But for some values of the parameters there exists a linear vector field on three dimensional Eucledian vector space whose time one map is T. We can analyze what happens to the flow of this vector field on one of the coordinate hyperplanes (see Fig. 5 in Sect. 4). In words this figure depicts, that if you have a bad ratio of growth inhibitor to growth factor cancer grows and if you have a good ratio cancer is eradicated. We can modify the dynamical system to model giving chemo therapy or immune therapy and discuss the consequences. We fit the model predictions to a Gompertz function and this gives a good fit for some values of the parameters (see Figs. 1, 2, 3 and 4). A main topic of the present paper is a mass action kinetic model for cancer growth. This gives a three dimensional ODE model, for which the first orthant is positively invariant. We discretize the linearization of this nonlinear ODE and with appropriate parameter definitions we recover the model T of Sect. 1. For some parameter values the model T induces a two dimensional map of the plane, see Sect. 5 . [ABSTRACT FROM AUTHOR]

Several studies have examined ICT in relation to stock market development, economic growth and development and other macroeconomic variables. Most of the studies have been on the developed and emerging economies. Studies have been relatively scanty for the developing economies, especially Sub-Saharan Africa. Thus, knowledge gap has been identified in the literature for the African Continent. Pooled data were used in this paper to spur further studies on financial markets in Africa. This paper employed data on functional models adapted from Gompertz curve model for technology diffusion to investigate the effects of ICT on market outcomes of two leading stock exchange markets in Africa during the 1995-2015 periods. Results showed mixed effects of most ICT metrics and moderating variables in the study. Specifically, the effect of mobile telephone on all market indicators was positive and significant. Further, aggregate effect of the ICT proxies and moderating variables on all market indices was statistically significant. The ICT proxies accounted for positive dynamics in market outcomes, market operations and, thus, sine quo non to growth and development of the markets and financial sectors in the Continent. Therefore, more investments in ICT wares and innovation by the stock exchanges and financial sectors in Africa were recommended. [ABSTRACT FROM AUTHOR]

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Recently, the mobile telephony market of Kazakhstan has experienced rapid growth to the extent that the number of subscriptions exceeded the total population since 2009. In order to understand this phenomenon, this paper analyzes the diffusion of mobile telephony in Kazakhstan. Estimating the penetration rate of mobile telephony with the three most popular diffusion models, Logistic, Gompertz and Bass, it was found that the best fit model of the diffusion process for mobile telephony in Kazakhstan is Gompertz. Furthermore, we performed an empirical analysis to determine the significant factors that affect the fast diffusion speed and found that population and fixed line subscriptions are significant factors. Finally, we attempted to predict the demand of mobile telephony in Kazakhstan over the next ten years using a modified Gompertz model in which affecting factors are incorporated. [ABSTRACT FROM AUTHOR]

Copyright of Investigación Económica is the property of Universidad Nacional Autonoma de Mexico, Facultad de Economia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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This paper focuses on the measurement of human capital, specifically on the growth of cognitive skills (CS) during the higher education at university. CS have already been evaluated in a macroeconomic perspective inside the neoclassical growth models, but not still in a micro perspective. However the measure of educational quality and learning process is still an issue not fully addressed. The micro approach allows the researcher to focus on the evaluation of CS acquisition process. Based on these measurements, different types of CS accumulation can be identified. We will investigate CS through nonlinear latent growth modeling, and we will apply this methodology to administrative data of an Italian university. [ABSTRACT FROM AUTHOR]

The role of tumor suppressor genes in longevity has not been studied in detail. The aim of this study is to define the effects of haploinsufficiency for various tumor suppressor genes on life span in Drosophila melanogaster. We find that both females and males heterozygous for one of the tumor suppressor genes, l( 3) hem, hyd, gd, ex, or ft, have a shorter life span. In addition, we performed a statistical analysis using the Gompertz model to show gene and sex-specific differences in mortality rates in these mutant models. Analysis of the Gompertz curve shows a significant increase in the age-dependent mortality parameter (α) for l( 3) hem, hyd, and gd mutant males. At the same time, males deficient in gd show a rise only in the background mortality parameter ( R). In turn, only ex mutation results in a specific increase the age-dependent mortality in females. We propose that these aging and mortality effects are associated with interactions between specific tumor suppressors and signal transduction pathways mediated by hedgehog ( hyd), Notch ( gd), and Hippo ( ex and ft). [ABSTRACT FROM AUTHOR]

This study was aimed to unravel the productive and reproductive performance of Black Bengal goats under two feeding regime and fitting a growth curve function to predict the weaning weight in the semi-intensive system. The initial and subsequent live weight at bi- weekly intervals for the experimental males and females up to age at sexual maturity and then up to kidding and after kidding up to next conception was recorded. It was observed that the live weight of goats was declined after parturition from the live weight at advanced pregnant stage in both two feeding regimes and dam's weight was loosening after kidding to 30 days at a rate of 42g/day but then it was increased steadily. Similarly the adult buck was also loosening their weight when they used for serve to the doe. The kids birth weight was varied between sex. In the first few weeks, the kids live weight was increased faster than it was slower up to mature age. The kidding rate and kidding interval for both feeding regime was ranging from 1.50 to 1.62 and 220 to 243 days, respectively. The Gompertz curve function was fitted with the test day basis collected data. It was observed that the Gompertz function parameters were positive and the predicted weaning weight values were higher than the actual values. Significant differences were observed between feeding regime, but not between sexes. [ABSTRACT FROM AUTHOR]

• Growth of early weaned calves can be explained by a generalized Richards growth curve. • Male and female calves responded differently to early weaning. • Heifers increase their growth rate after approximately 60 kg of live weight. • Special care must be taken with weaning heifers that weigh less than 80 kg. In semi desert environments, prone to droughts, beef cow performance can be improved by early weaning. This study aimed to evaluate the growth curve of early weaned calves in a semidesert temperate area such as Patagonia, Argentina, using a classical growth curve model. Hereford and crossbred (3/4 Hereford x 1/4 Aberdeen Angus) calves (n = 56), born in spring (September - November), from multiparous cows (4 to 8 years old), were weaned at 45–145 d of age, with 43–156 kg live weight and placed in a feedlot. After a period of adaptation, the calves were fed ad libitum with a diet of corn (48%), soybean expellers (12%) and alfalfa (40%), which was adjusted weekly for the previous week's intake. The animals were weighed weekly. The growth curve was defined by a Bayesian stepwise model selection process based on Richards' growth curve. The resulting model is a Gompertz-like curve (near-zero shape parameter), in which females experience a change in growth rate at about 62.7 kg, from where their r increases from 0.0065 to 0.0121 becoming similar to that of males. The whole model had a high fit, with a generalized r2 of 0.8782. The average daily gain (ADG) was 0.804 kg/day for female calves and 0.934 kg/day for male calves. Female calves weighing less than 80 kg had an ADG of 0.672 kg/day, and those weighing more had an ADG of 0.847 kg/day. The current growth curve shows that it is possible to achieve high ADG in early weaned calves, confirming that early weaning is a viable alternative to make production systems more efficient in semi desert environments like Patagonia. Knowing the relationship between concentrate feeds and livestock prices, farmers will be able to decide whether early weaning is a profitable alternative or not is a profitable alternative. However, special care must be taken when weaning heifers that weigh less than 80 kg to achieve high ADG. [ABSTRACT FROM AUTHOR]

We investigated the role that urbanization and plague may have played in changes in life expectancy amongst artists in the Low Countries who were born between 1450 and 1909. Artists can be considered to be representative of a middle-class population living mostly in urban areas. The dataset was constructed using biographical information collected by the Rijksbureau voor Kunsthistorische Documentatie in The Hague, the Netherlands. As early as the beginning of the sixteenth century, life expectancy at age 20 amongst the artists had reached 40 years. After a substantial decline in the late sixteenth and the early seventeenth centuries, when plague hit the region, life expectancy at age 20 began to rise again, and this upward trend accelerated after 1850. The life expectancy of female artists commonly exceeded that of males, and sculptors had better survival prospects than painters. In comparison with elite groups in the Low Countries and elsewhere in Europe, life expectancy amongst the artists was rather high. [ABSTRACT FROM AUTHOR]