scholarly journals AGEING AND THE INFLUX OF WATER INTO RADISH ROOT-HAIR CELLS

1950 ◽  
Vol 34 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Hilda F. Rosene
Keyword(s):  
Root Hairs ◽  
Water Entry ◽  
Humid Atmosphere ◽  
Water Influx ◽  
Radish Root ◽  
Sufficient Distance ◽  
The Mean ◽  
The Times ◽  
Radish Seedlings ◽  
Root Hair Cells

A micropotometric device previously described by the writer was used to determine quantitatively the velocity of water influx in cubic microns per square micron of hair surface per minute of comparatively older and younger root hairs of radish seedlings in a humid atmosphere at 29° ± 1°C. when the micropotometers were filled with Hoagland solution at pH 6.8. In each experiment, measurements were made on two hairs of different length and different age on a given root and the hairs were inserted into the micropotometers a sufficient distance so that the area of immersion, 13,200µ2, was the same in each instance. The range of velocities of water influx through the immersed surface was 4.46 to 1.16µ3/µ2/min. for the younger and shorter hairs which varied in length from 280 to 460 microns. The range of velocities of water influx through the immersed surface of the older hairs which varied from 661 to 2300 microns in length was 1.94 to 0.47µ3/µ2/min. The data indicate that water entry slows down in older hairs independent of root length. Estimations were made of the times to replace hair volumes based upon the mean velocities of water entry of the immersed areas. It was found that the time for the hairs to absorb an amount of water equivalent to their own volumes under the conditions specified was a matter of minutes or less; the range was 0.90 to 8.51 minutes.

Diurnal changes in the plasma concentrations of LH and hypothalamic contents of LHRH-I and LHRH-II in the domestic hen

1991 ◽  
Vol 130 (3) ◽  
pp. 457-462 ◽  
Author(s):  
S. C. Wilson ◽  
R. T. Gladwell ◽  
F. J. Cunningham
Keyword(s):  
Plasma Concentration ◽  
Diurnal Rhythm ◽  
Laying Hens ◽  
Plasma Concentrations ◽  
Posterior Hypothalamus ◽  
Anterior Hypothalamus ◽  
Diurnal Changes ◽  
The Mean ◽  
The Times ◽  
Lh Secretion

ABSTRACT Diurnal changes of LH secretion in sexually immature hens of 9, 11, 13 and 15 weeks of age consisted of 25–40% increases in the mean concentrations of LH in plasma between 15.00 and 18.00 h, i.e. between 2 h before and 1 h after the onset of darkness. During this time there was a tendency for the mean contents of LHRH-I in the anterior hypothalamus and posterior hypothalamus to increase by 21–74% and 20–56% respectively. In hens of 9 and 15 weeks, diurnal changes in the plasma concentration of LH closely paralleled those of LHRH-I content in the posterior hypothalamus. In contrast, the diurnal rhythm of LH secretion in hens of 11 and 13 weeks was more marked and plasma concentrations of LH continued to rise steeply between 18.00 and 21.00 h, i.e. between 1 and 4 h after the onset of darkness. At 11 weeks, this was associated with a reduction (P<0·01) in the contents of LHRH-I and LHRH-II, particularly in the anterior hypothalamus. In laying hens, a diurnal decline (P<0·01) in the plasma concentration of LH between 1 and 4 h after the onset of darkness was preceded by a fall (P<0·05) in the content of LHRH-I in the posterior hypothalamus and in the total hypothalamic content of LHRH-II (P<0·01). In all groups of hens, irrespective of the times of day at which tissue was taken, significant (P<0·05–<0·001) correlations between the contents of LHRH-I and LHRH-II in the anterior hypothalamus were observed. It is concluded that a diurnal rhythm of release of LHRH-I may drive the diurnal rhythm of LH secretion. Thus, in sexually immature hens of 9 and 15 weeks and laying hens in which diurnal changes in plasma LH were small there were parallel changes in the content of LHRH-I in the posterior hypothalamus. However, where the plasma concentration of LH was increased substantially, as at 11 weeks, there was a decline in the hypothalamic contents of LHRH-I. A simultaneous fall in the hypothalamic content of LHRH-II raises the possibility of a causal relationship between the activities of LHRH-II, LHRH-I and the release of LH. Journal of Endocrinology (1991) 130, 457–462

I. On the solar-diurnal variation of the magnetic declination at Pekin

1860 ◽  
Vol 10 ◽  
pp. 360-374
Keyword(s):  
Diurnal Variation ◽  
First Year ◽  
Magnetic Observatory ◽  
Magnetic Element ◽  
Monthly Means ◽  
The North ◽  
The Hours ◽  
The Mean ◽  
The Times ◽  
North End

When the first year of hourly observations of the declination, January 1 to December 31st, 1841, was received at Woolwich from the Magnetic Observatory at Hobarton, and when means had been taken of the readings of the collimator-scale at the several hours in each month, and these monthly means had been collected into an­nual means, it was found that the mean daily motion of the declina­tion magnet at Hobarton presented, as one of its most conspicuous and well-marked features, a double progression in the twenty-four hours, moving twice from west to east, and twice from east to west; the phases of this diurnal variation were, that the north end of the magnet moved progressively from west to east in the hours of the forenoon, and from east to west in the hours of the afternoon ; and again from west to east during the early hours of the night, return­ing from east to west during the later hours of the night: the two easterly extremes were attained at nearly homonymous hours of the day and night, as were also the two westerly extremes; the ampli­tudes of the arcs traversed during the hours of the day were con­siderably greater than those traversed during the hours of the night. When, in like manner, the first year of hourly observations, July 1st, 1842, to June 30th, 1843, was received from the Toronto Ob­servatory, and the mean diurnal march of the declination magnet was examined, it was found to exhibit phenomena in striking corre­spondence with those at Hobarton. At Toronto also a double pro­gression presented itself, of which the easterly extremes were attained at nearly homonymous hours, as were also the westerly; whilst the hours of extreme elongation were nearly the same (solar) hours at the two stations, but with this distinction, that the hours at which the north end of the magnet reached its extreme easterly elongation at Hobarton were the same, or nearly the same, as those at which it reached its extreme westerly elongation at Toronto, and vice verâ Pursuing, therefore, the ordinary mode of designating the direction of the declination by the north end of the magnet in the southern as well as in the northern hemisphere, the diurnal motion of the magnet may be said to be in opposite directions at Hobarton and Toronto; but if (in correspondence with our mode of speaking in regard to another magnetic element, the Inclination) the south end of the magnet is employed to designate the direction of the motion in the southern hemisphere, and the north end in the northern hemisphere, the apparent contrariety disappears, and the directions, as well as the times of the turning hours, are approximately the same at both stations.

Development of a commercial price schedule for producers and processors of lambs

1989 ◽  
Vol 29 (1) ◽  
pp. 23 ◽  
Author(s):  
DL Hopkins
Keyword(s):  
Multiple Regression ◽  
Carcass Weight ◽  
Commercial Application ◽  
Commercial Development ◽  
Time And Motion ◽  
Motion Study ◽  
The Mean ◽  
Fat Score ◽  
The Times ◽  
Mean Time

Equations were developed to predict the weight of trimmed retail (bone-in) cuts, trim, fat and bone from 321 lamb carcasses, ranging in carcass weight from 4.8 to 26.8 kg and in fat depth at the GR site (12th rib) from 1 to 31 mm. For commercial application, the equations were developed using a multiple regression program with the predictors carcass weight and GR. All equations explained a large amount of the variation in component weights (r2 = 0.76-0.99). A time and motion study using 172 carcasses showed that the times required to butcher carcasses of low fat (score 1 and 2) were similar. Likewise the mean time taken to butcher score 3 carcasses was similar to that of score 1 carcasses. However, it took significantly longer (P<0.05) to butcher score 3 carcasses than score 2 carcasses, and score 4 and 5 carcasses than score 3 carcasses. In addition, the mean times taken to butcher score 4 and 5 carcasses were significantly different (P< 0.05). By using multiple regression analysis it was shown that carcass weight, fatscore, their interaction and the butcher all significantly affected the butchering time. The findings of this work are discussed as they apply to the commercial development of price schedules and show that, when based on yield, lean heavy carcasses are more profitable for processing.

Effect of Visual Complexity in Identification of Tachistoscopic Images

1994 ◽  
Vol 78 (3) ◽  
pp. 971-978 ◽  
Author(s):  
Robert Geheb ◽  
Keith E. Whitfield ◽  
Linda Brannon
Keyword(s):  
Reaction Time ◽  
Left Hemisphere ◽  
Right Hemisphere ◽  
Visual Complexity ◽  
Reaction Times ◽  
Right Cerebral Hemisphere ◽  
The Mean ◽  
The Times ◽  
The Right ◽  
Mean Reaction Time

The present study of gender differences in hemispheric processing involved identification of tachistoscopically presented images of varying complexity. A computerized tachistoscopic program was administered to 24 men and 34 women. Time to identify contour and detailed pictures presented to the left or right cerebral hemisphere was recorded. Mean reaction time for contour pictures was significantly faster than for detailed pictures, and mean reaction time to the right hemisphere was significantly faster than that to the left hemisphere. The mean reaction time for men to identify pictures exposed to the left hemisphere was significantly slower than that for exposure to the right hemisphere for women. The mean reaction time for both men and women to identify contour pictures exposed to the right hemisphere was significantly faster than the mean time to identify detailed pictures presented to the left hemisphere. The interaction of gender, hemisphere, and complexity was also significant in that mean reaction times for men to identify detailed pictures presented to the left hemisphere were slower than the times for women to identify contour pictures presented to the right hemisphere. The results are discussed in relation to theories about hemispheres, gender, and differences in picture features.

scholarly journals Controlled thawing of foods

2000 ◽  
Vol 18 (No. 5) ◽  
pp. 194-200 ◽  
Author(s):  
K. Hoke ◽  
L. Klíma ◽  
R. Grée ◽  
M. Houška
Keyword(s):  
Power Level ◽  
Point Of View ◽  
Hot Water ◽  
Similar Process ◽  
Hot Air ◽  
Air Temperatures ◽  
The Mean ◽  
Level 1 ◽  
The Times ◽  
Mean Time

The various ways of thawing of model food made for comparison of these processes from point of view of duration. The experiments were conducted under condition that the surface temperature of the thawed food did not overcome 15°C. Shortest mean time of thawing was achieved for vacuum-steam thawing. Regarding to the regime chosen the time of thawing varied between 18.4–29 min. The similar process of vacuum thawing with steam generated from hot water placed below the food was also successful. For this process the mean time of thawing was predicted between 30.5 and 35 min. If the starting temperature of the water was below the boiling point at vacuum level in the chamber the time of thawing was much longer (about 49 min). For hot air thawing we have tested two regimes with temperature of air 50 and 70°C. For both air temperatures the times of thawing were similar being 52.1 and 53.6 min, respectively. Microwave thawing was depending on the power of microwave oven. The time of thawing was achieved 28.9 min at power level 1, at power level “thawing” the process duration was 34.4 min.

Evaluation of the effect of mosquito age and prior exposure to insecticide on pyrethroid tolerance in Anopheles mosquitoes (Diptera: Culicidae)

1999 ◽  
Vol 89 (4) ◽  
pp. 329-337 ◽  
Author(s):  
M.H. Hodjati ◽  
C.F. Curtis
Keyword(s):  
Anopheles Stephensi ◽  
Age Effect ◽  
Wild Populations ◽  
Anopheles Mosquitoes ◽  
Confirmatory Tests ◽  
Resistant Strains ◽  
The Mean ◽  
The Times ◽  
Short Time ◽  
Effect Of Age

AbstractThe times for knockdown of resistant and susceptible strains of both Anopheles stephensi Liston (DUB234 and BEECH) and A. gambiae Giles (RSP and KWA), on exposure to a permethrin impregnated net were determined to evaluate the effect of age on susceptibility to permethrin. The mean knockdown times of pyrethroid resistant strains of A. stephensi and A. gambiae were significantly shorter if they were 10 days old (either fed or unfed), as compared with those of newly emerged mosquitoes. Based on KT50 values, the resistance ratios between resistant and susceptible A. stephensi were 3.5 and 2.2 for the newly emerged and 10-day-old mosquitoes, respectively. After 1 h exposure to paper impregnated with 0.25%permethrin, mortality of newly emerged individuals of the susceptible and resistant strains of A. stephensi was significantly less than when they were 10 days old. Irritability by permethrin was less with the resistant strain of A. stephensi. In the other strains irritability declined significantly with age. Pre-exposure of susceptible mosquitoes of BEECH and IRAQ strains of A. stephensi for a short time to permethrin did not increase tolerance when the mosquitoes were re-exposed 24 h later. Because of the age effect and the possibility of an effect of pre-exposure under some circumstances, confirmatory tests on newly emerged F1 individuals reared from wild collected mosquitoes are recommended in monitoring for resistance in wild populations.

Experimental inquiries relative to the distribution and changes of the magnetic intensity in ships of war

1833 ◽  
Vol 2 ◽  
pp. 218-218
Keyword(s):  
Single Fibre ◽  
Magnetic Intensity ◽  
Glass Vessel ◽  
The Mean ◽  
The Times ◽  
Magnetic Meridian ◽  
Brass Wire

This paper contains the details of experiments made on board several vessels, with a view of determining the influence of the iron in the ships upon the compass under different circumstances and situations. The instrument used for determining the intensity consisted of a magnetized cylindrical bar, 2·5 inches long and three eightieths of an inch diameter, delicately suspended by a single fibre of the silkworm, to the extremity of an adjusting screw, which worked in the cap of the glass vessel inclosing the bar. A brass wire also passed through the cap for the purpose of placing the bar at right angles to the magnetic meridian previous to its being put into a state of oscillation. On the days devoted to the experiments on ship-board, the time of making 50 vibrations of the bar was determined in the centre of a meadow, of which the substratum was dry slate, by a mean of six sets of experiments, the time being accurately registered to quarter seconds. The instrument was then taken on board, and placed in succession at the different stations of the ship, and the mean of six sets of experiments determined at each station with the same precautions as on land. The times, says the author, of performing the oscillations on shore, and at each of the assumed points in the ship, necessarily gave the magnetic intensity at each station in terms of the terrestrial intensity, which in this case was represented by 100.

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