Empirical Growth Curves Research Articles

Modelling Hygroscopic Particle Growth in Human Lung Airways

An inhaled particle deposition program has been modified to take hygroscopic aerosol growth into account. The new model uses empirical or theoretical growth curves to calculate aerosol particle deposition in each airway generation. A substantial body of research on hygroscopic growth of particles has evolved which uses thermodynamic modelling to relate postulated temperature and humidity conditions in the lung to particle growth rate as a function of time (Ferron and Busch, 1996). Our approach differs from these models by simply using empirical or theoretical aerosol growth curves. Using this approach, we show that predicted inhaled particle growth and regional deposition patterns are similar to those predicted by other models.

Postnatal Growth and Age Estimation in the Indian Pygmy Bat Pipistrellus mimus

The Indian pygmy bat Pipistrellus mimus produced two young per litter, which were altricial at birth. Empirical growth curves were derived by measuring length of forearm, body mass, and length of the total gap of the fourth metacarpal-phalangeal joint. Length of forearm and body mass followed a linear pattern of growth until day 20 and subsequently reached stability. The length of the total gap of the metacarpal-phalangeal joint showed a linear increase up to 20 days, followed by a linear decrease until ca. 80 days when it closed. A quantitative method of estimation of age was derived from values of length of forearm and length of the total gap of the fourth metacarpal-phalangeal joint during the preflight (first 20 days) and postflight stages, respectively. Width of the 95% confidence level was ±0.6 days at a mean length of forearm of 15.1 mm, and it was ±0.9 days at a mean length of the total gap of the fourth metacarpal-phalangeal joint of 2.0 mm. Initiation of flight occurred 21 days after birth. At 33 days of age, young were able to forage on their own. Females experienced their first parturition at the mean age of 112 days. Females of P. mimus apparently attains sexual maturity within 2 months after birth, which may be the youngest age for sexual maturity in a bat.

Postnatal Growth and Development in the Mexican Free-Tailed Bat (Tadarida brasiliensis mexicana): Birth Size, Growth Rates, and Age Estimation

Based on mark-recapture data, we quantified changes in body mass, length of forearm, and lengths of the total, proximal, and distal epiphyseal gaps of individual Mexican free-tailed bats (Tadarida brasiliensis mexicana) from birth to peak lactation. We used these data to develop empirical growth curves, derive growth rates, establish age-predictive equations, and compare growth parameters based on three nonlinear growth models. Length of forearm and body mass of neonates averaged 18.5 mm ? 0.7 (SD) and 3.2 g + 0.3, respectively. Mean body mass of pups increased linearly for the first 3 weeks, by which time they had achieved ca. 80% of the mean postpartum mass of adult females. Thereafter, body mass remained relatively stable until a small decrease in body mass was observed at the beginning of the 6th week when young first began to fly. The growth trajectory of the forearm also was linear for the first 3 weeks, but, thereafter, increased more slowly until average adult dimensions were reached in the 6th week. Length of total epiphyseal gap increased to its maximum size during the first 2 weeks and subsequently decreased in a linear fashion. Secondary centers of ossification appeared in the metacarpal and first phalanx of the fourth digit at ca. 14 days, thus, making it possible to quantify age-related changes in the proximal and distal epiphyseal gaps. The equation for estimating age based on length of the forearm is valid when this dimension is -39 mm, whereas the equation for estimating age based on length of the total epiphyseal gap is valid when length of the forearm is >39 mm. Together, these two equations make it possible to estimate the age of pups from 1 to 42 days of age in T. brasiliensis. Of the three nonlinear growth models (logistic, Gompertz, and von Bertalanffy), the logistic equation provides the best fit to the empirical curves for length of forearm and body mass.

Column densities of Interstellar Gas in the direction of the starε Ori (B0 IA)

We have investigated the star e Ori with IUE high resolution SWP spectrum in order to derive curve of growth and column densities of Al II, Si II, S II, Fe II, Ni II and Zn II. It has been possible to fit these ions on one empirical curve of growth with a velocity parameterb = 11 km s−1 for the star studied.

Growth, mortality and recruitment rates of giant clams, Tridacna gigas and T. derasa, at Michaelmas Reef, central Great Barrier Reef, Australia

Growth, recruitment and mortality rates of a population of giant clams (Tridacna gigas and T. derasa) were monitored between 1978 and 1985 in a 2.7 ha study area on Michaelmas Reef, Great Barrier Reef. The initial 1978 census revealed the presence of 1166 T. gigas and 44 T. derasa. For T. gigas, the Fabens method provided growth-parameter estimates of L∞ = 85.7 cm, K = 0.07 and to = 0.732 year. The generated von Bertalanffy growth curve was a relatively poor fit to an empirical growth curve. A better description of growth was obtained for younger clams by using a forced value of L∞, = 80 cm, yielding K = 0.105 and to = 0.145 year. There was marked variability in the growth rate of individual clams, which has implications for the aquaculture industry. Average annual mortality rates in two census intervals (1978 to 1980-81 and 1980-81 to 1985) were 3.4 and 10.7% respectively. A comparison of the calculated size structure (assuming constant recruitment) with the observed size structure clearly suggested that recruitment was not constant and had declined drastically from a peak in the 1950s. For the much smaller population of T. derasa, the Fabens routine yielded estimates of L∞ = 46.91 cm, K= 0.108 and to = -0.188 year. The average annual mortality rate was 4.4%. Trends in recruitment could not be determined because of the small sample size. This study has highlighted the need for follow-up studies of this and other populations of giant clams if we are to understand more fully the processes of growth, recruitment and mortality in wild stocks and the implications for stock management and aquaculture.

ON THE GROWTH-CURVE METHOD FOR CALIBRATING STELLAR PHOTOMETRY WITH CCDS

ABSTRACT Stellar photometry with CCDs usually relies on the construction of aperture growth curves for its ultimate calibration. In the past this has been a tedious chore requiring a great deal of human intervention, mostly to select data suitable for defining empirical growth curves from data sets containing some corrupt values. A computer program has been written which incorporates a priori knowledge of the typical morphology of stellar profiles and is capable of taking a synoptic overview of all the aperture growth curves from an entire night or observing run. The program is thus enabled to make its own judgments as to the reliability of individual data points and to draw physically reasonable growth curves without human supervision, even for individual frames with insufficient or badly contaminated data. The program runs quickly and independently and produces results not noticeably inferior to those obtained by traditional hand-and-eye methods.

Ultraviolet studies of the interstellar gas in the direction of the stars AE Aur (09.5V) andθ 2 Ori A (09.0V)

We have studied high-resolution SWP spectra of AE Aur andθ2 Ori A, obtained from the International Ultraviolet Explorer Satellite; and derived curve of growth and column densities ofCii,Cii*, Alii, Siii, Siii*,Sii, Crii, Feii, Niii, and Znii. It has been possible to fit these ions on one empirical curve of growth with a velocity parameterb=13 km s−1 for both stars.

Growth of rock lobsters (Jasus edwardsii)in Fiordland, New Zealand

Abstract Moulting periods, growth per moult, annual and long‐term growth, moult frequency, and growth rates were estimated for recaptured Jasus edwardsii tagged between Thompson and Caswell Sounds in Fiordland, New Zealand. Males grew faster than females, and both showed a progressively decreasing growth rate. For females immature at tagging and recapture, there was no relationship between growth per moult or annual growth and size. For females immature at tagging and mature at recapture, and for mature females, there was a significant decrease in growth per moult and annual growth with an increase in size. Some immature females moulted twice each year and others once, while all mature females moulted once. Empirical growth curves were better descriptors of the growth of females than the von Bertalanfiy curve, especially for smaller and younger individuals. For males there was no relationship between growth per moult and size; however, there was a significant decrease in moult frequency and annual growth ...

Abundance of interstellar aluminum

New observations of Al II 1670 A, the only line of the dominant ionization stage of interstellar aluminum detected to date, are presented. Observations of ionized silicon are used to define an empirical curve of growth from which aluminum depletions can be derived. The depletion ranges from a factor of 10 in alpha Vir, with E(B-V) of about 0.04, to a factor of 1000 in omicron Per. The depletion is similar to that of iron, but a factor of 2-10 lower than that for silicon in the same stars. The observations of near-UV lines using the Copernicus V1 tubes with removal of a high cosmic-ray-induced fluorescent background are described.

Growth of Tagged American Lobsters, Homarus americanus, in the Bay of Fundy

Sphyrion-tagged lobsters recaptured in the Bay of Fundy during 1977–80 yielded mean annual molt increment and molt probability data for male and female lobsters of 60–171 mm carapace length from which growth curves were calculated. In addition, a multiple regression model was used to generate growth curves from premolt size, number of molt periods lobsters were exposed to, and growth increment data for 850 tagged lobsters at liberty for 1–5 yr. Von Bertalanffy parameters were calculated from these empirical growth curves, which suggest that lobsters take 20–35 yr from time of hatching to reach 200 mm carapace length in the Bay of Fundy. Analysis of pleopods indicated that the majority of lobsters molt during August–October each year. Growth per molt of immature (60–94 mm carapace length) and mature (95–170 mm carapace length) male and immature female lobsters was arithmetic (regression slope 1.04) but was regressive for mature females (slope 0.95). Mature lobsters molted less frequently than immature lobsters, but mature males grew more rapidly than mature females. Most mature females in the Bay of Fundy are on a 2-yr molt–reproductive cycle. About 20% of ovigerous females recaptured within 2 yr after release had extruded eggs a second time without molting, confirming that multiple egg extrusions between molts do occur naturally.

Recruitment and growth patterns of juvenile marine teleosts caught at King's Beach, Algoa Bay

The recruitment patterns of six teleosts were studied at King's Beach, Algoa Bay. February to May marked the major recruit· ment period for Dip/odus sargus, Lithognathus mormyrus, Rhabdosargus g/obiceps and Trachurus capensis. The major recruitment of Sarpa sa/pa fry took place between August and September. Pomadasys olivaceum fry of < 5 cm total length were caught throughout the year indicating an extended breeding period. The estimated growth rates of new recruits between February and May (autumn/winter) was 0,60 cm month - 1 for L. mormyrus, 0,75 cm month -1 for R. g/obiceps and 0,40 cm month -1 for T. capensis. The empirical growth curve derived for S. sa/pa indicated a growth rate of 0,75 cm month -1. No growth estimates could be made for P. olivaceum or D. sargus.

Interstellar absorption lines in the spectrum of Gamma Velorum

Copernicus scans of selected interstellar absorption lines in the UV spectrum of Gamma Vel are analyzed, together with ground-based data, to obtain column densities for various ion states of C, N, O, Na, Mg, Al, Si, P, S, Cl, Ar, Ca, Mn, Fe, and CO. N I and O I are fitted to a single empirical curve of growth with a velocity parameter (b) of 8 km/s; Mg II, Si II, P II, S II, Mn II, and Fe II are fitted to another curve with b between 3 and 9 km/s. Abundance determinations relative to H I show that: (1) C, N, P, S, and Ar are probably close to their solar values; (2) O may be depleted by about a factor of 2; (3) Mg, Al, Si, Cl, Mn, and Fe are depleted by a factor of 4 or more: (4) Al is depleted by at least a factor of 10 in the H II region; and (5) both N V and O VI are present, but not C IV. The N V/O VI ratio implies that the electron temperature in the H II region is about 275,000 K.

Parameter estimation in nonlinear regression models1

Publisher Summary This chapter discusses the concept of parameter estimation in nonlinear regression models. As for linear models, the least squares method occurs as the most important estimation method because many favorable properties known from the linear theory can be at least asymptotically assured. The solution of the corresponding nonlinear optimization problem requires in general iterative methods. In concrete case studies, the selection of an appropriate procedure from the large set of iterative methods proposed in the literature, the choice of starting guesses, incremental change, and step size requires a lot of experience. The examples of nonlinear regression models are empirical growth curves, exponential models, and Coob–Douglas models. The least squares estimation is the main estimation method in nonlinear regression. The formulation as an inadequate least squares problem may be needed because of the fact that the numerical treatment may be much simpler or, looking on statistical efficiency, it could seem to be reasonable to diminish the dimension of parameters. However, the investigation of weighted inadequate least squares approximation (WILSA) is of basic importance, taking into consideration that the model choice problem in the nonlinear case is difficult. The chapter discusses the problem of approximating a nonlinear response function in a given linear set of functions, polynomial approximation, the consistency of least squares estimators, asymptotic distribution of least-squares estimators, asymptotic optimality of GLSE without normality, maximum likelihood estimation, robust nonlinear regression, and confidence regions of the model.

Determination of the line shapes of atomic nitrogen resonance lines by magnetic scans

A technique is given for calibrating an atomic nitrogen resonance lamp for use in determining column densities of atoms in specific states. A discharge lamp emitting the NI multiplets at 1200 A and 1493 A is studied by obtaining absorption by atoms in a magnetic field (0-2.5 T). This magnetic scanning technique enables the determination of the absorbing atom column density, and an empirical curve of growth is obtained because the atomic f-value is known. Thus, the calibrated lamp can be used in the determination of atomic column densities.

An Empirical Light Intensity Relationship for Elemental Mercury Emissions

Mercury in both its elemental and compound forms is an important environmental trace contaminant. One method of determining the concentration of mercury involves the application of atomic emission spectrometric principles. Most practical analytical applications are devoted to the construction of empirical growth curves (i.e., analytical signal vs concentration). The concentration of an unknown is then determined by interpolation. Ideally, at very low concentrations the signal will be found to be linearly related to the ground state concentration of the atoms which give rise to the signal. At higher atomic concentrations, the relationship becomes complex.

NI I transition probabilities and the solar nickel abundance

view Abstract Citations (51) References (24) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Ni I transition probabilities and the solar nickel abundance. Lennard, W. N. ; Whaling, W. ; Scalo, J. M. ; Testerman, L. Abstract Absolute transition probabilities have been measured for 97 lines from 11 levels in Ni I using the beam-foil lifetime and branching-ratio technique. We have measured equivalent widths at the disk center from the Preliminary Edition of the Kitt Peak Solar Atlas for 49 of the above lines. An empirical solar curve of growth has been constructed to test the consistency of the transition probabilities and equivalent widths. The solar Ni abundance has been computed (1) by matching the equivalent widths of the 10 weakest lines, and (2) by fitting the profiles of 19 lines. Both methods agree within experimental uncertainty and yield an average photospheric Ni abundance of 6.28 + 0.09. Subject headings: abundances, solar - transition probabilities Publication: The Astrophysical Journal Pub Date: April 1975 DOI: 10.1086/153538 Bibcode: 1975ApJ...197..517L Keywords: Abundance; Line Spectra; Nickel; Solar Spectra; Transition Probabilities; Atomic Energy Levels; Data Acquisition; Radiative Lifetime; Spectral Line Width; Tables (Data); Solar Physics full text sources ADS |

Frequency and intensity measurements on the quadrupole spectrum of molecular hydrogen

The quadrupole spectrum of molecular hydrogen has been investigated with spectroscopic instruments of high resolution and a large 44-meter multiple reflection absorption cell. The frequencies of seven lines in the 1-0 band and two lines in the 2-0 band were measured. Pressure shifts were obtained for five lines in the 1-0 band. These data were used to obtain precise molecular constants for the first few vibrational states. Intensity measurements on the lines of the 1-0 and 2-0 bands and the S(1) line of the 3-0 band were made and corrected by means of an empirical curve of growth. These measurements are compared with theoretical calculations of the hydrogen quadrupole matrix element.

Das organische Wachstum und seine Gesetzmäßigkeiten

The author gives a survey on the theory developed by him on organic growth. He succeeds in proving a relation between metabolism and growth. His hypothesis can be expressed by a simple differential equation. In the group of the metazoa, three different types of metabolism are found which can be distinguished from the point of view of the relation between oxygen consumption and body-weight. Growth formulas may be deduced for the different types of metabolism which are in good accordance with the empirical growth curves. The importance of growth principles for morphogenesis is stressed. It may be concluded that significant phenomena of the ontogenetic and phylogenetic process may be interpreted as manifestations of growth principles and may thus be submitted to a quantitative analysis.