Difference In Rate Of Increase Research Articles

Growth of embryonic softshell turtles is unaffected by uremia

We injected eggs of softshell turtles (Trionyx spiniferus) with solutions of urea at the midpoint of incubation to induce different levels of uremia in developing embryos. The experiment was undertaken as a test of the hypothesis that urea inhibits intermediary metabolism of embryos and thereby causes a reduction in their rates of growth. The injection protocol elicited a physiologically realistic range of uremias, but we found no evidence that metabolism or growth of embryos was impaired even at the highest levels of uremia. The most likely explanation for our results is that the uremias commonly encountered during natural incubation by embryos of this and other species of turtle are insufficient to inhibit intermediary metabolism. Thus, the influence of the hydric environment on metabolism and growth of embryonic turtles apparently is not mediated by differential rates of increase in the concentration of urea in body fluids.

Cyclophytic effects on wood structure in Pinusradiata D. Don. II. Tracheid morphology

The effects of apical ontogeny on xylem morphology in Pinusradiata were examined in grafted trees and in clonal pairs of trees grown from cuttings from hedge- and tree-form donors (H and T). At the time of sampling the grafted rootstocks were 21 years old, and trees from H and T plants were 11 years old from the date of planting rooted cuttings. In grafted trees tracheids were longer, and the rate of increase in tracheid length was greater above the graft. Since growth rings were narrower above the graft, the difference in rate of increase in tracheid length above and below the graft was greater when plotted against distance from pith than against growth ring number. In comparisons of H and T plants, T plants (expected to be at a later stage of apical ontogeny) produced fewer but longer and wider tracheids. Cell wall volumes per tracheid were greater in T plants, but because the tracheid diameters in H plants were smaller, wall volumes per unit tracheid volumes were consistently greater in H plants. The role of apical ontogeny in explaining patterns of anatomical variation within the stem is discussed. H and T plants of radiata pine were from the three mainland populations: Año Nuevo, Monterey, and Cambria. The Año Nuevo population produced the greatest numbers and the largest tracheids. The Monterey population had the shortest tracheids amongst H plants, but their tracheid lengths were equal to those of the Año Nuevo population in T plants.

Ｖｅｎｏｕｓ ｏｃｃｌｕｓｉｏｎ負荷時の血液凝固線溶系の変動について

The present study aimed to evaluate the blood coagulability and fibrinolytic activity in thrombotic patients during the venous occlusion test. Subjects were 7 healthy adults and 16 patients with myocardial infarction, 2 patients with cerebral infarction. Measured were ATIII, PLG, α2PI, P-C, TPA, VIIIC, VIIIRAG, FPA, FPBβ15-42. Before occlusion, mean levels of VIIIRAG in the venous blood were higher and those of P-C were lower in patient group than in control group. After 10 minutes' occlusion, there was no significant difference noted in increase rate of VIIIRAG and TPA between patient and control groups.In conclusion, Venous stasis induces the release of TPA and VIIIRAG without significant difference in increase rate of these substances between patient and control groups. However, the lower level of P-C and higher level of VIIIRAG observed in thrombotic patients indicated that patient group was in hypercoagulable state.

The evolution of r- and K-strategies

The evolution of a population of organisms will be dependent upon the ecological circumstances in which it lives. It has been suggested that organisms in constant environments will be subject to natural selection acting to influence their equilibrium population density, but in organisms in temporally variable environments natural selection will act more on differences in rates of increase in population size. These two types of selection have been called r- and K-selection. A quantitative relationship between the optimum genotype of an organism and environmental variability is calculated, and shown to depend upon the trade-off between evolutionarily possible values of r and K.

RESISTANCE TO APHIS CRACCIVORA (HOMOPTERA:APHIDIDAE) IN SELECTED VARIETIES OF COWPEA

Nearly 200 varieties of cowpea, Vigna unguiculata (L.) Walp, were screened for resistance to the cowpea aphid, Aphis craccivora Koch. Three varieties known to be resistant in West Africa were highly susceptible to an aphid population from the southern United States. Four other varieties, however, inhibited growth of the southern United States population both in the laboratory and in the field. Life-table comparisons using a resistant and a susceptible variety revealed a three-fold difference in the intrinsic rate of increase and a more than twenty-fold difference in the net reproductive rate. High nymphal mortality and low fecundity on resistant plants were largely responsible for these differences.

Comparative analysis of physiologic responses to three different maximal graded exercise test protocols in healthy women

The purpose of this study was to compare the three most commonly used maximal graded exercise test (GXT) protocols in healthy women. Submaximal and maximal metabolic and hemodynamic responses were determined from two treadmill protocols, Bruce and Balke, and a bicycle protocol, in 49 women. Maximum oxygen uptake (VO 2 max) was significantly different among protocols (Bruce = 40.3, Balke = 38.4, and Bike = 36.6 ml/kg·min −1). Maximum heart rate (HR max) was significantly lower during Bike (178 beats/min) than during Bruce (182) and Balke (183) protocols. No differences in rate of increase in HR or systolic blood pressure (BP) per increase in multiples of the rest metabolic (METs) were found between Bruce and Balke protocols. The rate of recovery of HR and systolic BP was not different among tests. Comparisons of active and sedentary groups showed differences in VO 2 max and submaximal HR and recovery HR at common minutes; however, the rate of increase in HR and systolic BP during exercise and the rate of decrease during recovery were not significantly different. Prediction of VO 2 max with Bruce and Balke protocols from treadmill time was r = 0.91 (SEE ± 2.7 ml/kg·min −1) and r = 0.94 (SEE 2.2 ml/kg·min −1), respectively. These data suggest a difference between men and women in increased HR and systolic BP per METs increase in exertion.

Ecological differences among clones of Daphnia pulex Leydig.

Natural populations of Daphnia pulex that reproduce by obligate parthenogenesis include a number of clones. Studies on two common and two rare clones from southwestern Ontario revealed significant differences in their intrinsic rates of increase, competitive abilities, rates of ephippial egg production, and lifespans. Environmental factors such as temperature and food type had large inluences on the rate of increase of each clone. Differences in rates of increase among clones were most pronounced at temperatures higher than those encountered in nature. In general, the covariance of life history traits among clones was high. The outcome of competitive encounters between clones was deterministic and in most cases was unaffected by temperature. Clones with high rates of increase tended to be better competitors than those with low rates of increase.

Quality of oil from acid delintered cottonseed

AbstractOils were extracted experimentally by direct solvent and prepress solvent processes from saw delintered cottonseed as well as from some of the same seed delintered with dilute sulfuric acid. Oils were refined, bleached and deodorized. Deodorized oils were stored in an air oven at 60 C for 30–35 days. Approximately twice a week, stored samples were analyzed for peroxide value. No significant differences in rate of increase of peroxide value were found among the oils.

Interaction between External and Internal Conditions in the Development of Photosynthetic Features in a Grass Leaf

Lolium multiflorum plants were grown under a low- or high-light regime until third leaves had emerged to one-third their final length and then were transferred to a contrasting light regime. At this stage, the leaf possesses a tissue-age gradient from tip to base; thus, the reversibility of light-acclimated responses as a function of the degree of differentiation was analyzed in individual leaves.Regional responses in the apical, medial, and basal zones of leaves of transferred plants were analyzed before and after light transfer and compared to leaves from plants kept in constant light. Leaves transferred from low to high light showed rapid recovery and attained light-saturated rates and ribulose bisphosphate carboxylase activities equivalent to those of high-light controls. However, fresh or dry weight and chlorophyll content were intermediate between those for the two irradiances. In the reciprocal experiment, the apical leaf zone retained high-light characteristics for maximum photosynthesis, whereas all the other functional parameters adapted rapidly to values characteristic of their low-light counterparts (equivalent foliar zones).On the ultrastructural level, chloroplasts in the apical zone of transferred leaves surpassed their respective constant light controls in absolute membrane content and size. However, a shift to high light induced an increase in plastid volume and, in relative terms, the plastid membrane content was diluted. A shift to low-light treatment led to smaller membrane-dense plastids. The ultrastructural readaptation is realized through differential rates of increase in plastid volume and lamellar content. Proplastids (leaf base), or juvenile plastids having reached an intermediate developmental stage (leaf middle zone) at the time of transfer, took on characteristics of the latter light regime (equivalent to controls).These results provide evidence for rapid reacclimation processes under changing light regimes and suggest a capacity for regional light responses along the leaf.

Size‐sorting during suspension transportation—lognormality and other characteristics

ABSTRACTGrain size distributions of the suspended loads above a bed of bimodal size distribution (size range 2‐00‐0.04 mm) were studied in a laboratory flume at water velocities varying from 42 to 160 cm/s. With increase of velocity the phi (logarithmic) size distribution of the suspended particles (at 5‐20 cm above the bed) changed from a strongly skewed to a nearly symmetrical, unimodal form (nearly lognormal) through an intermediate bimodal stage. At low velocity the skewness of the distribution changed from positive to negative with increase of height. The experiments indicate that lognormality of‘weight frequency’ distribution of grain sizes is a transitional feature, attained through size sorting within a critical range of velocity and height above a sand bed of a given composition.The observed changes in the size distribution patterns were effected by a differential rate of increase in weight in the different size classes in suspension with increase of flow velocity. The phenomenon could be explained by the equation of relative suspension concentration which relates the relative concentration of a suspended particle of a particular diameter to the flow velocity of the turbulent fluid and the height of suspension above the bed.

Differential rates of increase in pontine tyrosine hydroxylase and dopamine-β-hydroxylase activities after reserpine

Differential rates of increase in pontine tyrosine hydroxylase and dopamine-β-hydroxylase activities after reserpine

Increase of Dwarf Mistletoe Infections on Young Lodgepole Pine

Field studies in southern Alberta revealed a rapid increase in the incidence of dwarf mistletoe (Arceuthobiumamericanum Nutt. ex Engelm.) in young lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.). In 10 areas of infected trees, the number of infections increased exponentially at a mean rate (base 10 logarithm) of 0.24 per year (range: 0.19–0.29 among areas). Differences in rates of increase among areas were not significant.

Alkaline Phosphatase: Lability in Fresh and Frozen Human Serum and in Lyophilized Control Material

Abstract On storage, the activity of alkaline phosphatase (AP) in human serum increases. This has been known, but largely ignored, for 40 years. Improved instrumentation makes this lability more obvious and more important because errors from other sources have been decreased. With a stabilized spectrophotometer we quantitated the effects of time and temperature on AP activity of human sera and of lyophilized "control" material. Activities of 10 fresh sera increased by an average of 0.9, 2.7, and 6.1% in 6, 24, and 96 h; that of pooled serum, frozen and thawed, increased about 1% per hour. For 22 lots of reconstituted lyophilized material the increase ranged from 3 to 22% in 6 h. Refrigeration greatly decreased, but room temperature restored, the rates of change. Freezing decreased the activity of some lots, and most had a smaller rate of increase. Generally, the lower the initial activity of a given lot, the greater was the rate of increase. The difference in rate of increase among materials from different sources varied widely. Delay in measurement of serum AP activity is not the only source of potentially serious error; time and temperature variations are also, when lyophilized materials are used.

Family Types and Family Headship: A Comparison of Trends among Blacks and Whites

The decrease in the proportion of husband-wife black families in recent decades has led to discussions of the breakdown of the Negro family. This hypothesis is examined, along with the hypothesis that the economic status of black men accounts for the instability of black families. The findings indicate that a growing proportion of adult Negroes are heading families. Differential rates of increase, especially the sharp rise in headship rates among black women, explain the changing distribution of families by type. Rather than confirming a trend toward a breakdown of the black family, these data report the changing living arrangements of adults. Available information indicates that socioeconomic status is positively related to the likelihood that a man will head a husband-wife family.

The effect of salt regimens on the development of (Na +-K +)-dependent ATPase activity during the growth of salt glands of ducklings

1. 1. A Mg 2+-activated, ouabain-sensitive (Na +-K +)-ATPase and a ouabain-insensitive Mg 2+-ATPase were characterized in salt gland homogenates of the domestic duck. 2. 2. 3 days after hatching, experimental birds were given 1% aqueous NaCl to drink for 12 h and fresh water for the remainder of each day. Control ducklings were maintained exclusively on fresh tap water. In homogenates of salt glands from experimental birds the specific activity of ATPase reached maximal levels in 9 days. (Na +-K +)-ATPase increased by a factor 4.1 and Mg 2+-ATPase increased by a factor of 1.8. There was no increase in ATPase activity in homogenates from control birds. 3. 3. Homogenates of glands from birds drinking only fresh water, after being maintained on the salt-water regimen for 22 days, exhibited a logarithmic decrease in (Na +-K +)-ATPase activity and in 9 days reached the level of activity recorded for control birds maintained only on fresh water. The Mg 2+-ATPase activity decreased rather slowly for the first 5 days on fresh water, and then dropped rapidly during the last 4 days of the experiment. 4. 4. The increase in ATPase levels in the salt glands of birds on the salt-water regimen is not cation-specific: both KCl and MgCl 2 regimens are capable of increasing this level, although neither is as effective as NaCl. 5. 5. Differential rates of increase and decrease of (Na +-K +)-ATPase and Mg 2+-ATPase activity resulting from various salt diets suggest that these activities may not be a consequence of bimodal functioning of the same enzyme.

Organization as a Key to Police Effectiveness

Citing evidence on intercity differences in crime rates, as well as differences in rates of increase for several kinds of crime, this paper argues that police departments differ in their effectiveness. The key to an understanding of effectiveness lies in the way police departments themselves are organized. How individual police men perform their occupational duties depends in part on how these duties are defined. In order to understand these definitions and the pressures which affect the way police perform their work, it is necessary to adopt a "systemic" view of legal and illegal forces in society. Determinants of police effectiveness are ex plored, through examples from the control of organized crimes, by relating the way departments interact with other legal and illegal organizations.

The Effect of Temperature and Feeding on the Intrinsic Rate of Increase of Three Species of Hydra

The use of the fresh water polyp, hydra, as an experimental animal in many facets of biological research has greatly increased since the difficulties of mass culturing were overcome by Loomis (1953) and Loomis and Lenhoff (1956). The continual proliferation of the cells of the adult hydra results partially in the formation of new individuals through asexual budding, rather than an increase in the size of the adult. In addition, cells are continually being lost from the tips of the tentacles and from the peduncle and, under certain conditions, through formation of gonads and the release of their products. For this reason, in part, hydra is considered to be an immortal animal (Brien 1953). The concern of this study is only with the reproductive potential resulting from asexual budding. Estimates of the reproductive potential of hydra are relatively scarce. Loomis's study (1954) on an estimate for Hydra Jittoralis has been a step in this direction. On the other hand, consideration of the variability of the rate of increase among individuals of the same species and between species is completely lacking. Loomis (1954) has shown that the rate of increase for H. littoralis is a function of the environment. His examination of several environmental factors (certain ions, oxygen tension, pH, temperature, and nutritional status) indicates some effect on this population parameter. However, the relative significance of each factor interacting with each of the others is not clear. The question also arises as to whether there is any inherent difference in the intrinsic rate of increase between species of hydra and whether this might be related in some way to their conditions of existence in nature. This study was designed to examine in detail the intrinsic rate of increase for 3 species of hydra under 2 temperatures and 2 states of nutrition and to assess the interactions between these factors.

Studies on the adaptability of three breeds of sheep to a tropical environment modified by altitude IV. Role of the fleece in thermoregulation in German Merino ewes

The influence of fleece on thermoregulation in German Merino ewes was investigated in Rhodesia. Comparative heat tolerances of Persian Blackhead, indigenous Native and shorn and unshorn Merino ewes were obtained during the hottest month of the year in Northern Rhodesia. The main thermolytic responses in unshorn, partially shorn and completely shorn Merino ewes were measured at 7.0 a.m.; 10.0 a.m.; 1.0 p.m. and 4.0 p.m. during April in Southern Rhodesia.1. Unshorn Merino ewes showed more and shorn Merino ewes less effective body temperature regulation than Persian or Native ewes. High heat tolerance in unshorn Merinos was due primarily to insulation by the fleece and not to more efficient physiological thermolysis than in hair breeds. No ewe showed signs of undue thermal stress and feed intake was not affected by heat.2. Increases in rectal temperature and respiratory rate between 7.0 a.m. and 1.0 p.m. of Merinos in Southern Rhodesia were related inversely to fleece length. Body temperature did not differ significantly at 1.0 p.m. owing to differential rates of increase in respiratory rate.3. Magnitude of the diurnal fluctuation in skin temperature was also related inversely to fleece length. Partially shorn ewes, however, began with and maintained highest skin temperature through the heat of the day. In all groups skin temperature fell after 10.0 a.m. although ambient temperature continued to rise. This fall could not be attributed to sweating since moisture secretion declined simultaneously.

The Growth of the Locust Embryo

ABSTRACT Three measures of the growth of the embryo of Locusta migratoria migratorioides (R. & F.) were determined from the third to the twelfth days of development at 30° C. These measures were the dry weight, reduced weight, and number of nuclei. Measurements of the density of the embryo were also made and used with the R.W. to calculate the wet weight. The same measurements of the intact egg were taken throughout development. The growth in dry weight of the locust embryo from the third to twelfth days of development appeared closely comparable with that of vertebrate embryos such as the chick embryo and could be described by the usual double logarithmic relation with growth constants of closely comparable values. Increase in R.W. and wet weight could be similarly described from the third to ninth days after which the rate of increase fell away more rapidly than expected. Increase in nuclear number occurred at a higher rate than any of the other measures up to the ninth day after which no further increase above a total of about two million nuclei could be detected. As in some vertebrate embryos, cell multiplication seemed not to parallel growth in weight. The implications of the differences in rates of increase of these measures were considered. From the third to ninth days the embryo was approximately 90 per cent, water, the density of the dry material may have increased and the dry weight per nucleus decreased rapidly to a constant value. After the ninth day there appeared to be a fall in water content and dry density and an increase in the dry weight/nuclear number ratio. The density of the wet embryo increased steadily after the sixth day. The total loss in dry weight of the egg due to respiration was about 20 per cent., an amount typical of many insect eggs. The eggs increased in weight by about 120 per cent., chiefly during the fourth and fifth days. The percentage water content rose from about 50 per cent, to about 80 per cent. Changes in the density of the eggs reflected perfectly the changes in water content. The R.W. of the eggs was constant except for a rise of about 40 μ g. during the fourth and fifth days. It was suggested that this could be accounted for by the presence in the chorion of about 0 04 /xl. of air which was displaced when water uptake took place after the third day. This would also have accounted for the very small difference in the measured changes in density compared with those calculated from the water intake. A constant R.W. and a large decrease in dry weight imply that the density of the dry material of the eggs must have increased at the same rate as the respiratory loss in dry weight. Combustion of fat might account for this.

Some aspects of gene dosage in N- type sheep

The dominant and recessive mimic genes N and nr produce increased birthcoat hairiness in New Zealand Romney lambs. This hairiness has been studied in lambs of different genotypes by three different methods. It has been found: (i) that in individual lambs there is a gradient in hairiness from the shoulder patch to the britch; (ii) increases in hairiness with increasing dosage of the N and nr genes conform to this gradient; (iii) with any single increase in N-gene dosage there is a differential rate of increase in hairiness on different positions. These results are explained on the hypothesis that the primary gene action is linear, but the gradient is modified by a threshold and possibly by a ceiling effect in the production of birthcoat medullation.