IV. On the expansion by heat of metals and alloys

1867 ◽  
Vol 15 ◽  
pp. 220-222
Keyword(s):  
Specific Gravity ◽  
Metals And Alloys ◽  
The Body ◽  
The Other ◽  
Different Temperatures ◽  
The Mean

In a paper “ On the Expansion by Heat of Water and Mercury” *, a method of determining the expansion of bodies is described, by which good results can be obtained with comparatively small quantities of the substances to be experimented with. This method, that of weighing the body in water at different temperatures, has been employed for the present research. The results obtained are given in the following Tables:— From the above the following conclusion is drawn-namely, that just as it may be said that the specific gravity of an alloy is approximately equal to the mean specific gravities of the component metals , so also from the foregoing we may deduce that the volume which an alloy will occupy at any temperature between 0° and 100° is approximately equal to the mean of the volumes o f the component metals at the same temperature, or, in the other words, the cubical or linear coefficients o f expansion by heat of an alloy between 0° and 100° are approximately equal to the mean of the cubical or linear coefficients of expansion by heat o f the component metals .

scholarly journals The Respiration of some Planktonic copepods II. The Effect Of Temperature

1953 ◽  
Vol 31 (3) ◽  
pp. 447-460 ◽  
Author(s):  
D. T. Gauld ◽  
J. E. G. Raymont
Keyword(s):  
Respiratory Rate ◽  
The Body ◽  
The Other ◽  
Effect Of Temperature ◽  
Acartia Clausi ◽  
Temora Longicornis ◽  
Different Temperatures ◽  
Planktonic Copepods ◽  
The Difference ◽  
The Relationship

The respiratory rates of three species of planktonic copepods, Acartia clausi, Centropages hamatus and Temora longicornis, were measured at four different temperatures.The relationship between respiratory rate and temperature was found to be similar to that previously found for Calanus, although the slope of the curves differed in the different species.The observations on Centropages at 13 and 170 C. can be divided into two groups and it is suggested that the differences are due to the use of copepods from two different generations.The relationship between the respiratory rates and lengths of Acartia and Centropages agreed very well with that previously found for other species. That for Temora was rather different: the difference is probably due to the distinct difference in the shape of the body of Temora from those of the other species.The application of these measurements to estimates of the food requirements of the copepods is discussed.

Further evidence for the sorting out of cells in the differentiation of the cellular slime mold Dictyostelium discoideum

Development ◽  
1971 ◽  
Vol 25 (3) ◽  
pp. 457-465
Author(s):  
J. T. Bonner ◽  
T. W. Sieja ◽  
E. M. Hall
Keyword(s):  
Specific Gravity ◽  
Cell Size ◽  
Dictyostelium Discoideum ◽  
The Other ◽  
Cellular Slime Mold ◽  
Spore Size ◽  
Slime Mold Dictyostelium Discoideum ◽  
Cellular Slime ◽  
The Mean ◽  
Different Strains

The observation of Takeuchi's that the denser cells of Dictyostelium discoideum tend to sort out towards the anterior end of the migrating slug (and the lighter cells towards the posterior end) has been confirmed using spore size as a method of identifying cells populations. A fraction of the anterior and posterior ends of a slug are isolated and allowed to fruit; their spores are then measured. The same is done for preaggregation cells which have been separated into heavy and light fractions, using Takeuchi's technique of centrifugation of the cells in a dextrin solution equal to the mean specific gravity of the cells. Invariably, in three experiments with different strains of D. discoideum, the spores derived from dense cells corresponded perfectly with spores derived from the anterior cells of the slug, and a similar correspondence was found between spores derived from light cells and posterior slug cells. Contrary to a previous view (Bonner, 1959), cell size did not always correlate with position; in one strain the anterior cells were larger, in the other two they were smaller.

Estimation of body fat in young women

1962 ◽  
Vol 17 (6) ◽  
pp. 967-970 ◽  
Author(s):  
A. W. Sloan ◽  
J. J. Burt ◽  
C. S. Blyth
Keyword(s):  
Specific Gravity ◽  
Water Temperature ◽  
Body Fat ◽  
Young Women ◽  
Iliac Crest ◽  
The Body ◽  
Body Density ◽  
Multiple Correlation ◽  
Skin Fold ◽  
The Mean

The body density of 50 healthy young women was determined by underwater weighing, and five skin-fold thicknesses and five girths were measured on each subject. The mean body density was 1.0467 g/ml (sd ± 0.0122), corresponding to 20.06 ± 4.63% by weight of fat in the body by the formula of Keys and Brozcaronek or 22.91 ± 5.58% by the formula of Siri. The mean specific gravity at water temperature 37.5 C was 1.0537 (sd ± 0.0122), corresponding to 22.13 ± 7.08% fat by the formula of Rathbun and Pace. The skin-fold measurement that showed the highest correlation with a composite criterion of skin folds was that over the iliac crest (r = +.92). The best prediction of body density was from skin-fold measurements over the iliac crest and back of arm, which gave a multiple correlation of –.74. Submitted on October 9, 1961

scholarly journals Integration of Proprioceptive and Visual Position-Information: An Experimentally Supported Model

1999 ◽  
Vol 81 (3) ◽  
pp. 1355-1364 ◽  
Author(s):  
Robert J. van Beers ◽  
Anne C. Sittig ◽  
Jan J. Denier van der Gon
Keyword(s):  
Visual Information ◽  
The Body ◽  
The Other ◽  
Proprioceptive Information ◽  
Position Information ◽  
Left Hand ◽  
The Mean ◽  
The Right ◽  
Variable Errors ◽  
Available Information

Integration of proprioceptive and visual position-information: an experimentally supported model. To localize one’s hand, i.e., to find out its position with respect to the body, humans may use proprioceptive information or visual information or both. It is still not known how the CNS combines simultaneous proprioceptive and visual information. In this study, we investigate in what position in a horizontal plane a hand is localized on the basis of simultaneous proprioceptive and visual information and compare this to the positions in which it is localized on the basis of proprioception only and vision only. Seated at a table, subjects matched target positions on the table top with their unseen left hand under the table. The experiment consisted of three series. In each of these series, the target positions were presented in three conditions: by vision only, by proprioception only, or by both vision and proprioception. In one of the three series, the visual information was veridical. In the other two, it was modified by prisms that displaced the visual field to the left and to the right, respectively. The results show that the mean of the positions indicated in the condition with both vision and proprioception generally lies off the straight line through the means of the other two conditions. In most cases the mean lies on the side predicted by a model describing the integration of multisensory information. According to this model, the visual information and the proprioceptive information are weighted with direction-dependent weights, the weights being related to the direction-dependent precision of the information in such a way that the available information is used very efficiently. Because the proposed model also can explain the unexpectedly small sizes of the variable errors in the localization of a seen hand that were reported earlier, there is strong evidence to support this model. The results imply that the CNS has knowledge about the direction-dependent precision of the proprioceptive and visual information.

scholarly journals XVIII. On the direction assumed by plants

1848 ◽  
Vol 138 ◽  
pp. 253-275
Keyword(s):  
Solid Body ◽  
The Body ◽  
The Other ◽  
External Object ◽  
Metallic Wire ◽  
Slight Tendency ◽  
The Family ◽  
The Mean ◽  
Perennial Herbs

The plants with tendrils are very numerous. According to Mr. Palm there are about five hundred, divided into seventeen families. Of these, one hundred and sixty have a ligneous stem, eighty-three are perennial herbs, and one hundred and seventeen are annuals. My experiments on the mode of curling-up of these organs were made on the tendrils of the Tamus comunis , a plant of the family of the Asparageæ. The tendrils of this plant seem to be a thread-like degeneration of the footstalk of a leaf, whose place they occupy on the stem of the plant. They are at first straight, and are implanted perpendicularly on the stem, so as to form almost a right angle with it; the extreme end of the tendril only has a slight tendency to bend towards the stem. When the tendril of the Tamus is touched by any solid body whatever on a point of its surface not too far from the extremity, it contracts itself from the outside inwards, forming at first a hook and then a curl, so as to embrace the body closely if that body be circular; if angular, the knot is only tight on the angles, and bulges out on the surfaces. When a first knot is tied, the end of the tendril continues to roll itself up in a coil, though not in contact with the body in that part, and the coil slides over the external object, coming nearer and nearer to it so as to embrace it several times: in the mean while, the other end of the tendril continues also to contract itself. In this way as many as seven or eight knots are formed. I have frequently seen three tied before my eyes within the space of a quarter of an hour on a metallic wire, small branches of wood, a pencil, my finger, &c. The contact of any solid body whatever is sufficient to produce this effect; so much so, that although the tendril is evidently destined by nature to support the creeper to which it belongs, by means of the urrounding plants, yet if it chances to meet a part of the very same plant of Tamus of which it is itself a portion, the contact causes it immediately to roll itself up around that portion.

scholarly journals Eye Movements and Body Images

1964 ◽  
Vol 9 (4) ◽  
pp. 336-344 ◽  
Author(s):  
E. Llewellyn Thomas ◽  
Eugene Stasiak
Keyword(s):  
Eye Movements ◽  
Visual Attention ◽  
Eye Movement ◽  
Psychiatric Patients ◽  
External World ◽  
The Body ◽  
The Other ◽  
Body Images ◽  
The Face ◽  
The Mean

The eye-movement patterns of nine hospitalized psychiatric patients were compared with those of ten non-patients when looking at pictures of themselves and others. There were highly significant differences between both the mean fixation times of the two groups and also between the area of the body to which they paid the most attention. The mean fixation times of all the non-patients grouped closely around 0.61 seconds whereas the patients varied between 0.12 seconds and 0.47 seconds and 0.72 seconds and 1.04 seconds. Non-patients looked at all body levels, but spent much more time looking at the face. Patients on the other hand paid much more visual attention to the body and tended to avoid the face. It is suggested that the variability in the fixation times and the tendency to avoid the face reflects a mechanism in the patient which is tending to avoid receiving information about certain aspects of the external world.

The analysis of the lactation curve into maximum yield and persistency

1930 ◽  
Vol 20 (2) ◽  
pp. 145-185 ◽  
Author(s):  
H. G. Sanders
Keyword(s):  
Mammary Gland ◽  
Negative Selection ◽  
Maximum Yield ◽  
The Body ◽  
External Factors ◽  
The Other ◽  
Lactation Curve ◽  
Nutritional Factor ◽  
The Mean ◽  
Selection For

An attempt has been made to analyse the lactation yield into its two components, maximum yield and persistency; the latter has been defined as the ratio of lactation to maximum yield, and has been measured by a S.F. calculated from , where R is the mean ratio for the month of calving concerned.Whilst, when corrections for external factors are applied, maximum and persistence are equally constant throughout the cow's life, these factors cause wider individual fluctuations with persistency; maximum yield is subject to a more rigid limit and may be largely determined by the area of the mammary gland, but persistency seems to be chiefly a nutritional factor—that is to say, it depends on the success of the mammary gland in competing with the other tissues of the body for the available nutriment. This leads to the view that persistency is higher in the dairy type of cow; it also appears to be associated with high constitution, for very definite positive selection is apparent with persistency, as compared to marked negative selection for maximum—this is attributed to pathological attrition falling more heavily on cows with high initial yield and low persistency.

Effects of Hypothermia and Hyperthermia on Fertilization in Rat Eggs

1956 ◽  
Vol 33 (2) ◽  
pp. 348-357
Author(s):  
C. R. AUSTIN
Keyword(s):  
Body Temperature ◽  
The Body ◽  
The Other ◽  
Direct Influence ◽  
Body Temperatures ◽  
Slowing Down ◽  
Other Hand ◽  
The Mean ◽  
Rat Eggs ◽  
G 13

The chilling of rats to body temperatures down to 4-7° C. before and during the time of ovulation had little effect upon the subsequent penetration of the eggs by spermatozoa. With a hypothermia of 0-1° C, however, there was almost complete and apparently permanent inhibition of spermatozoon entry. There seemed to be no reason to ascribe this effect to direct influence of cold on eggs or spermatozoa. Probably the failure of penetration arose largely from delay of ovulation, coupled perhaps with some derangement of the tubal environment. Hypothermia after ovulation but before and during the time of spermatozoon entry into the eggs temporarily but completely inhibited penetration when the body temperature was kept below 33° C. The likely explanation appears to be that ‘capacitation’ is prevented or greatly slowed by such temperatures. Hyperthermia, induced before and during the time of ovulation, somewhat reduced the mean number of eggs ovulated (from 10.5 to 7.5) and the proportion penetrated by spermatozoa (from 97 to 66%). The proportion of eggs penetrated by two or more spermatozoa was increased (from 19 to 28%), but the frequency of polyspermic fertilization did not change significantly. Hyperthermia after ovulation but before and during the time of spermatozoon entry also led to a greater proportion of eggs containing two or more spermatozoa (31%), but in addition it increased the incidence of polyspermy (from 2.5 to21.2%). Larger rats (170-200 g.) subjected to hyperthermia showed a higher frequency of polyspermy (34%) than smaller rats (100-130 g.; 13% polyspermy). Evidently the processes involved in the ‘zona reaction’ are reduced in efficiency by hyperthermia whether applied before or after ovulation. On the other hand, the block to polyspermy depends on processes that are much more sensitive to heat after ovulation. It is considered that the slowing down of the block to polyspermy is associated with ageing of the egg, that the ageing is accelerated by hyperthermia and that this effect is promoted in older rats.

The effect of incubation temperature on egg survival, hatchling traits and embryonic use of energy in the blue-tailed skink, Eumeces elegans

2003 ◽  
Vol 53 (1) ◽  
pp. 27-36 ◽  
Author(s):  
Lu Shou ◽  
Wei-Guo Du ◽  
Ji-Ke Liu
Keyword(s):  
Incubation Temperature ◽  
Tail Length ◽  
Yolk Sac ◽  
The Body ◽  
Effect Of Temperature ◽  
Egg Survival ◽  
Different Temperatures ◽  
The Mean ◽  
Locomotor Capacity ◽  
Hatchling Size

AbstractEggs of the skink, Eumeces elegans were incubated at 24, 27, 30 and 33°C to assess the effect of temperature on hatchling traits and embryonic use of energy. The mean incubation periods of eggs incubated at 24, 27, 30 and 33°C were 44.1, 28.0, 23.6 and 20.0 days, respectively. The mortality of embryos incubated at these temperatures did not differ significantly. The mean snoutvent lengths of hatchlings from 30 and 33°C were smaller than those of hatchlings from 24°C. In contrast, the body masses of hatchlings were not affected by temperature. Incubation temperature can also modify limb lengths of hatchlings. The fore and hind limb lengths of hatchlings from 24°C were longer than those of hatchlings from 33°C. However, tail length and head size (length and width) for hatchlings from different temperatures were similar. The locomotor capacity of hatchlings incubated at 33°C was completely destroyed, whereas that of hatchlings from the other three temperatures did not differ significantly in spite of the existence of differences in hatchling size. Moreover, incubation temperature affected the allocation of energy between carcass and yolk sac in the hatchling, although the overall conversion of energy from eggs to hatchlings was not influenced by temperature. Hatchlings from 30 and 33°C had a less developed carcass and more energy in yolk sac than those from 24°C. Thus, we can conclude that 33°C is not suitable for the incubation of E. elegans eggs, due to damage to the embryo.

Hairiness in wool and a method for selection based on the nature of the fibres and the distribution of halo hairs of the lamb's tail

1957 ◽  
Vol 49 (1) ◽  
pp. 1-18 ◽  
Author(s):  
F. M. Labban
Keyword(s):  
Fibre Diameter ◽  
The Body ◽  
The Other ◽  
Significant Difference ◽  
Mean Diameter ◽  
Wide Variability ◽  
The Mean ◽  
Highly Correlated ◽  
Different Parts

Hairiness in wool of Suffolk sheep as a fault was found to be associated with other defects like coarseness of wool fibres, hairiness of the britch, and the occurrence of pigmented fibres. The presence of these various defects was studied in the lamb's tail at docking time, and subsequently evaluated and correlated with the fleece.The tails were graded according to the nature of the fibres and the spread of halo hairs from the tip to the base into four principal grades which by further subgrading could be made into seven grades. The results were as follows:(1) There was wide variability in grades of tails within each flock.(2) Average grade of tails followed in general the mean quality of the adult fleece.(3) When Border Leicester were crossed with Welsh Mountain the tails of the two reciprocal crosses were found to be of hairy type of tail and nearly like the Welsh Mountain type.(4) The percentage of coloured tails in the least hairy grades was found to be inversely related to the quality of the tail grade and indirectly to the fleece quality.(5) The diameter of the wool fibres on the base of the tail is highly correlated with the diameter of fibres from the britch regions or mean fibre diameter from four regions of the body (mid-shoulder, midside, hip and britch).(6) The mean diameter of the wool fibres obtained from four different parts of the tail was correlated with those of the britch regions only.(7) The diameter and variability of fibres increased from shoulder to britch in the body and from base to tip in the tails.(8) The britch and tails of two groups of sheep, one group characterized by coarse and the other by fine britch and tail wool, were studied histologically. There were significant or highly significant differences in the following characteristics in the britch of the two groups: (a) total number of follicles, (b) primary follicles with no medulla, (c) total number of secondary follicles, (d) secondaries with no medulla, (e) secondaries with large medulla. The only type of follicle where a significant difference was found in the tail was in the number of secondary follicles with no medulla.

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