Comparative Studies of Accelerated Amphibian Metamorphosis

1928 ◽  
Vol 5 (3) ◽  
pp. 212-232
Author(s):  
E. A. SPAUL
Keyword(s):  
Anterior Pituitary ◽  
Potassium Cyanide ◽  
Cumulative Effect ◽  
Anterior Lobe ◽  
Rate Of Change ◽  
Tissue Response ◽  
X Rays ◽  
Rates Of Change ◽  
Inducing Factors ◽  
Qualitative Responses

(1) The administration of active anterior lobe extracts in solution is not effective in producing precocious transformation of tadpoles. (2) The rate of metamorphosis induced by injection of either thyroid or anterior pituitary depends within limits on the concentration of the initial dose. The time for completion with thyroid depends upon the total quantity given--a cumulative effect. The repetition of the stimulus given by a dose, the quantity per dose having maximum and minimum values, at suitable intervals decides the time of completion with anterior pituitary. (3) Susceptibility of tadpoles to metamorphosis inducing factors increases with age. (4) The effects produced by iodine in metamorphosis (mortality, reduction in size and shrinkage) agree more closely with those obtained in thyroid than pituitary treatment. (5) There is a differential response of certain tissues to concentrations of the thyroid but not to anterior pituitary. (6) Exposure of tadpoles to X-rays alters the susceptibility to factors accelerating metamorphosis. The effect increases with age. (7) Alcohol and potassium cyanide lower the response to thyroid and anterior pituitary stimulation according to the concentration and the age of tadpoles. (8) Normal rates of change are produced by thyroid and anterior pituitary in tadpoles under narcosis. The mortality is slightly higher with thyroid and depends on the concentration of the anaesthetic. Prolonged narcosis reduces the rate of change. (9) Precocious metamorphosis is not found in tadpoles after feeding upon the endostyle of Ciona intestinalis. (10) The relation to iodine, quantitative and qualitative responses of tadpoles to treatment, and the differential tissue response serve to differentiate between the metamorphic principles of the thyroid and anterior pituitary.

scholarly journals Disease-related disability burden: a comparison of seven chronic conditions in middle-aged and older adults

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Chieh-Ying Chou ◽  
Ching-Ju Chiu ◽  
Chia-Ming Chang ◽  
Chih-Hsing Wu ◽  
Feng-Hwa Lu ◽  
...  
Keyword(s):  
Older Adults ◽  
Physical Disability ◽  
Chronic Conditions ◽  
Chronic Condition ◽  
Disease Diagnosis ◽  
Rate Of Change ◽  
Middle Aged ◽  
Rates Of Change ◽  
Depression Status ◽  
Stage Disease

Abstract Background Although previous studies have explored the effect of chronic conditions on physical disability, little is known about the levels and rates of change in physical disability after a chronic condition diagnosis in middle-aged and older adults in the Asian population. The aim of this study is to ascertain the average levels and rates of change in the development of disability after disease diagnosis, as well as to determine the influences of sociodemographic and health-related correlates in the development of disability. Methods This is a retrospective cohort study analyzing data of nationally representative participants aged 50 and over with a chronic condition or having developed one during follow-ups based on data from the 1996–2011 Taiwan Longitudinal Study on Aging (TLSA) (n = 5131). Seven chronic conditions were examined. Covariates included age at initial diagnosis, gender, education level, number of comorbidities, and depression status. Physical disability was measured by combining self-reported ADL, IADL, and strength and mobility activities with 17 total possible points, further analyzed with multilevel modeling. Results The results showed that (1) physical disability was highest for stroke, followed by cancer and diabetes at the time of the initial disease diagnosis. (2) The linear rate of change was highest for stroke, followed by lung disease and heart disease, indicating that these diseases led to higher steady increases in physical disability after the disease diagnosis. (3) The quadratic rate of change was highest in diabetes, followed by cancer and hypertension, indicating that these diseases had led to higher increments of physical disability in later stage disease. After controlling for sociodemographic and comorbidity, depression status accounted for 39.9–73.6% and 37.9–100% of the variances in the physical disability intercept and change over time, respectively. Conclusions Despite the fact that a comparison across conditions was not statistically tested, an accelerated increase in physical disabilities was found as chronic conditions progressed. While stroke and cancer lead to disability immediately, conditions such as diabetes, cancer, and hypertension give rise to higher increments of physical disability in later stage disease. Mitigating depressive symptoms may be beneficial in terms of preventing disability development in this population.

Comparison of Transient Modeling Techniques for a Micro Turbine Engine

2006 ◽  
Author(s):  
Craig R. Davison ◽  
A. M. Birk
Keyword(s):  
Gas Turbines ◽  
Relative Size ◽  
Rate Of Change ◽  
Single Stage ◽  
Radial Compression ◽  
Shaft Speed ◽  
Transient Effects ◽  
Rates Of Change ◽  
Experimental Apparatus ◽  
Transient Modeling

A large number of papers have been published on transient modeling of large industrial and military gas turbines. Few, however, have examined micro turbines. The decrease in size affects the relative rates of change of shaft speed, gas dynamics and heat soak. This paper compares the modeled transient effects of a micro turbojet engine comprised of a single stage of radial compression and a single stage of axial expansion, with a diameter of 12cm. The model was validated with experimental data. Several forms of the model were produced starting with the shaft and fuel transients. Conservation of mass, and then energy, was subsequently added for the compressor, combustor and turbine, and a large inlet plenum that was part of the experimental apparatus. Heat soak to the engine body was incorporated into both the shaft and energy models. Heat soak was considered in the compressor, combustor and turbine. Since the engine diameter appears in the differential equations to different powers, the relative rates of change vary with diameter. The rate of change of shaft speed is very strongly influenced. The responses of the different transient effects are compared. The relative solution times are also discussed, since the relative size of the required time steps changes when compared to a large engine.

THE DEVELOPMENT OF A FEEDBACK MECHANISM BETWEEN THE OVARY AND THE DIENCEPHALIC-HYPOPHYSIAL SYSTEM IN THE RAT

1963 ◽  
Vol 26 (2) ◽  
pp. 287-NP ◽  
Author(s):  
J. PRESL ◽  
J. HORSKÝ ◽  
M. HENZL ◽  
J. JIRÁSEK
Keyword(s):  
Anterior Pituitary ◽  
Anterior Lobe ◽  
Feedback Mechanism ◽  
Histological Structure ◽  
Histological Investigation ◽  
Basic Information ◽  
Ovarian Weight ◽  
The Difference ◽  
Golgi Zone ◽  
Mucoid Cells

SUMMARY With the object of obtaining basic information concerning the establishment of the feedback mechanism between the ovaries and the diencephalic-hypophysial system (DHS), changes in the gonadotrophic activity and histological structure of the anterior pituitary lobe were determined in groups of rats 21 days following ovariectomy on the day of birth or at 5, 10, 15, 20, 30 and 50 days. It was shown that the gonadotrophic activity of the hypophysis of spayed females and non-spayed controls differed using the criterion of uterine weight of the recipient, following ovariectomy at birth. After spaying at the age of 5 days the difference was also statistically significant using the criterion of ovarian weight. Histological investigation showed that in animals ovariectomized at days 1 and 5 there was an increase in PAS-positive mucoid cells in the adenohypophysis with a distinct PAS-positive Golgi zone in the pale centre of the cytoplasm. The results of these experiments show that a feedback mechanism between the ovaries and the DHS becomes established at an age between (21–x) and (26–x) days, where x is the period necessary for the development of demonstrable post-castration changes in the anterior lobe. In view of the reported initiation of ovarian oestrogen production, the hypothesis is discussed that the feedback mechanism begins to function during very early post-natal life.

346. Measurements of the rate of change of temperature in high temperature-short time pasteurization plant

1947 ◽  
Vol 15 (1-2) ◽  
pp. 18-23
Author(s):  
F. Steghart
Keyword(s):  
High Temperature ◽  
Time Constant ◽  
Rate Of Change ◽  
Hot Water ◽  
Water Pipe ◽  
Temperature Changes ◽  
Rates Of Change ◽  
High Temperature Short Time ◽  
Short Time

It has recently been claimed that in modern high temperature-short time pasteurization plant fluctuations in temperature of the order of 1° F./sec. are unusual and probably artefacts, and that an instantaneous drop is certainly fictitious.It has, nevertheless, been shown that such rapid drops in temperature do in fact occur frequently in high temperature-short time plants of the type investigated. The plant investigated was not of the latest design incorporating devices for speeding up the control by injecting steam directly into the hot-water pipe.Temperature changes of the order of those in question were first observed by Mattick & Hiscox(1) of the National Institute for Research in Dairying, who carried out tests on pasteurization plant using a small mirror galvanometer with a very short time constant. The maximum rates of change were, however, not observed.

Factors Influencing Diuresis in Rats Following Total-Body X-Irradiation

1957 ◽  
Vol 189 (1) ◽  
pp. 11-14 ◽  
Author(s):  
E. Irene Pentz ◽  
Robert J. Hasterlik
Keyword(s):  
Adrenal Cortex ◽  
Anterior Pituitary ◽  
Adrenal Glands ◽  
Anterior Lobe ◽  
Posterior Pituitary ◽  
Cortical Control ◽  
Factors Influencing ◽  
X Irradiation ◽  
Diuretic Response ◽  
Total Body

An immediate diuresis has been observed in rats exposed to total-body x-irradiation ranging between 100 and 400 r. Since the highest dosage produced more consistent results, it was used in conjunction with extirpation of various glands and other organs in an effort to determine the mechanism that responds so promptly to x-irradiation. The anterior pituitary and the adrenal cortex are of prime importance in this reaction. Removal of the anterior lobe of the pituitary or removal of the adrenal glands is sufficient to completely inhibit diuresis following 400 r x-irradiation. This diuretic response is not dependent upon the presence of the posterior pituitary since animals having only this gland removed became diuretic following exposure to 400 r. The evidence suggests that the release of antidiuretic substances from tissues other than the posterior pituitary is under anterior pituitary-adrenal cortical control.

The Anthropocene equation

2017 ◽  
Vol 4 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Owen Gaffney ◽  
Will Steffen
Keyword(s):  
Limit Cycle ◽  
Late Quaternary ◽  
Rate Of Change ◽  
Earth System ◽  
Human Influence ◽  
Rates Of Change ◽  
The Earth ◽  
Uncertain Future ◽  
External Forces ◽  
Anthropogenic Forcings

The dominant external forces influencing the rate of change of the Earth System have been astronomical and geophysical during the planet’s 4.5-billion-year existence. In the last six decades, anthropogenic forcings have driven exceptionally rapid rates of change in the Earth System. This new regime can be represented by an ‘Anthropocene equation’, where other forcings tend to zero, and the rate of change under human influence can be estimated. Reducing the risk of leaving the glacial–interglacial limit cycle of the late Quaternary for an uncertain future will require, in the first instance, the rate of change of the Earth System to become approximately zero.

scholarly journals Environmental perturbations influence telomere dynamics in long-lived birds in their natural habitat

2013 ◽  
Vol 9 (5) ◽  
pp. 20130511 ◽  
Author(s):  
Yuichi Mizutani ◽  
Naoki Tomita ◽  
Yasuaki Niizuma ◽  
Ken Yoda
Keyword(s):  
Natural Habitat ◽  
Weather Conditions ◽  
Rate Of Change ◽  
Natural Setting ◽  
Stress Exposure ◽  
Free Living ◽  
Rates Of Change ◽  
Environmental Perturbations ◽  
Cellular Ageing ◽  
Telomere Dynamics

Telomeres are regarded as markers of biological or cellular ageing because they shorten with the degree of stress exposure. Accordingly, telomere lengths should show different rates of change when animals are faced with different intensities of environmental challenges. However, a relationship between telomere length and the environment has not yet been tested within a natural setting. Here, we report longitudinal telomere dynamics in free-living, black-tailed gulls ( Larus crassirostris ) through the recapture of birds of a known age over 2–5 consecutive years. The rate of change in telomere lengths differed with respect to year but not sex or age. The years when gulls showed stable telomere lengths or increases in telomere lengths (from 2009 to 2010) and decreases in telomere lengths (from 2010 to 2011) were characterized by El Niño and the Great Japan Earthquake, respectively. Both events are suspected to have had long-lasting effects on food availability and/or weather conditions. Thus, our findings that telomere dynamics in long-lived birds are influenced by dramatic changes in environmental conditions highlight the importance of environmental fluctuations in affecting stress and lifespan.

scholarly journals On the Regularity of Fluctuations in Annual and Secular Polar Motions

1972 ◽  
Vol 48 ◽  
pp. 61-67
Author(s):  
H. J. Abraham
Keyword(s):  
Rate Of Change ◽  
Rates Of Change ◽  
Amplitude Fluctuations ◽  
Chandler Frequency ◽  
Do So

It may become possible to explain much of the behaviour and remarkable regularity of fluctuations in reported annual and secular polar motions if the potential that causes an immediate excitation is also a factor in that excitation's rate of change afterwards.The Chandler frequency, for example, being a function of the deformation excitation, should then vary with the librational and nutational displacements of the pole of rotation. It is found that the frequency does in fact do so.The annual excitation would be affected as well. The steady and seasonal primary excitations are known to cause free and forced nutations that are accompanied by periodic secondary excitations. These would arise partly at once and partly in the course of time; they would modulate the primary annual excitation and also one another, according to the period of the beats between the annual and Chandler nutations. It is found that the reported annual excitation shows phase and amplitude fluctuations of this kind. (The data also show another large excitation that occurred briefly on two occasions).Finally, the amplitude and phase of the secular librations appear to have followed an expression that is obtained by integrating the rates of change of excitation. This expression is a function of the amplitude of the annual excitation and the period of the beats between the annual and Chandler nutations.

scholarly journals Period Changes in Magellanic Cloud Cepheids

1984 ◽  
Vol 108 ◽  
pp. 227-228
Author(s):  
H. Deasy ◽  
P. A. Wayman
Keyword(s):  
South African ◽  
Variable Stars ◽  
Period Change ◽  
Magellanic Clouds ◽  
Rate Of Change ◽  
Data Sets ◽  
Fractional Change ◽  
Rates Of Change ◽  
Observatory Data ◽  
Irregular Period

It has been found possible to obtain information on period change in data on 115 cepheid variable stars in the Magellanic Clouds (84 LMC cepheids and 31 SMC cepheids). Harvard Observatory data of the period 1910 to 1950 (collated by Payne-Gaposchkin and Gaposchkin) are combined with Dunsink Observatory observations carried out by C.J. Butler in 1966/67 and with South African Astronomical Observatory observations covering the years 1975–1977 by Martin, Thomas, Carter and Davies to derive mean periods for the intervals between the various data sets. Using these new periods in conjunction with the very accurate Harvard periods, seperate estimates of the time averaged fractional change of period per day, d/dt (ln P), with corresponding estimated errors, could be evaluated for two epochs, one around 1950 and the other around 1971. It was found that 70 stars give rates of change of period that are not significantly different from zero, that 20 stars have two values of rate of change of period that are in agreement at the two epochs (indicative of secular period change), while 22 stars give two disparate values of rate of change of period (indicative of irregular period changes).

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