Intervals Of Several Hours Research Articles

Retrograde rotation of the upper atmosphere of Venus

From June through September 1970, ultraviolet photographs of Venus, many of very high quality, were obtained by the International Planetary Patrol Program. A study of these photographs, together with some from other observatories, confirms previous reports that there is a retrograde circulation of the upper atmosphere of Venus. The sense of the rotation and its approximate period are determined from the motions of well-defined cloud features on five occasions over intervals of several hours. A distinctive feature similar to the “Y” described by Boyer and Guérin is seen many times over a forty-day interval (June 21 to August 1) and allows a good determination of the rotation period: 4.41 ± 0.02 days retrograde (synodic) or 4.50 days (sidereal). This value differs significantly from other estimates, but applies only to this particular forty-day interval. Apparent changes in the cloud features may be an indication that the circulation of the upper atmosphere of Venus is a complicated, time-dependent phenomenon. A temporal variation of the rotation period (caused perhaps by slight changes in the altitude of the ultraviolet cloud layer) is conceivable, so that exact agreement with other estimates of the period obtained at different times is not necessarily to be expected. Measurements of the latitude variation of the “Y” feature are too few and too uncertain to reveal systematic trends, although a large range (20°) in central latitude is indicated. The previous suggestion that a higher cloud layer may occasionally obscure the ultraviolet markings is consistent with the present observations.

Induction of heat in ovariectomized guinea pigs by brief exposure to estrogen and progesterone

Ovariectomized adult female guinea pigs were injected with 3 μg of estradiol benzoate and 36 hours later were implanted subcutaneously with silastic capsules of progesterone for 30 minutes, 2 hours, or continuously. All animals displayed lordosis in response to manual stimulation 3.6 to 4.1 hours after implantation. Control animals given empty capsules did not come into heat in response to estrogen alone. After several weeks' interval, the same animals were implanted with silastic capsules containing estradiol17β and injected 36 hours later with 0.4 mg of progesterone in sesame oil. The estradiol capsules were withdrawn 30 minutes, 1, 2, 6, or 12 hours after implantation, or were left in place continuously. Four out of five animals exposed to estradiol for 30 mintues and all animals in all other groups exhibited lordosis after a latent period of 3 to 6 hours from the time of progesterone injection. The data suggest that estrogen acts to stimulate a chain of events leading many hours later to a milieu optimum for the action of progesterone, which in turn induces a process culminating in the expression of sexual behavior after an interval of several hours.

Urinary excretion of hippuric acid and m- or p-methylhippuric acid in the urine of persons exposed to vapours of toluene and m- or p-xylene as a test of exposure.

<b>Ogata, M., Tomokuni, K., and Takatsuka, Y. (1970).</b><i>Brit. J. industr. Med.,</i><b>27,</b> 43-50. <b>Urinary excretion of hippuric acid and <i>m</i>- or <i>p</i>-methylhippuric acid in the urine of persons exposed to vapours of toluene and <i>m</i>- or <i>p</i>-xylene as a test of exposure.</b> Twenty-three male volunteers were exposed in groups of four or five to toluene and <i>m</i>- and <i>p</i>-xylene vapour for periods of 3 hours or of 7 hours with one break of an hour. Urine was collected at hourly intervals for several hours, and thereafter all urine was collected until 18 hours after the end of the exposure period, and was analysed for hippuric and methylhippuric acids. It was shown that hippuric acid was excreted equivalent to 68% of the toluene absorbed, and <i>m</i>-methylhippuric acid equivalent to 72% of the <i>m</i>-xylene absorbed. Up to hydrocarbon concentrations of 200 ppm the total quantity of hippuric acids excerted was proportional to the total exposure (ppm × hours). In descending order of precision the following were also related to exposure: rate of excretion during the exposure period; concentrations of hippuric acid in urine corrected to constant urine density; and concentrations in urine uncorrected for density. The last could not be used to calculate exposure, but the others could be to give screening tests to show whether workmen could have been exposed to concentrations greater than the maximum allowable. The effects of exposure on blood pressure, pulse rate, flicker value, and reaction time were measured. There were some variations which suggested that the MAC of toluene should be set higher than 200 ppm.

Etude de la rotation rétrograde, en 4 jours, de la couche extérieure nuageuse de Vénus

We review briefly photographic as well as spectrographic observations which have allowed us to prove and confirm the retrograde rotation of about 4 days of the external cloud layer of Venus. Certain configurations visible in ultraviolet light—in particular two spots having the shape of a horizontal Y—seem permanent, and we can establish their cartography. But the observations suggest that highlying clouds cover these configurations from time to time. An examination of the displacement of the equatorial spots during time intervals of several hours furnishes an instantaneous synodic rotation period somewhat larger than 4 days for the permanent spots. The synodic period is shorter for the variable spots. The observations of the periodic return, at the subsolar point, of the equatorial Y shaped configurations, suggest that the mean rotation period of these spots is remarkably constant and almost equal to 4 days. This period increases considerably when the spot latitudes are greater than ±6°. Ephemerides have been calculated for the years to come.

EFFECT OF BLUE AND YELLOW LIGHT DURING THE LATER DEVELOPMENTAL STAGES OF SPHAEROBOLUS

When fruiting cultures of Sphaerobolus are transferred from continuous light to darkness the discharge of global masses continues for 1 day but then stops for the next few days. Experiments are reported in which this darkness is interrupted after 24 hr by brief (0.5‐2 hr) treatment with light of different wavelengths and of equated low intensity (ca. 100 lux). Interruption by blue (ca. 448 mμ) or by green (ca. 500 mμ) light has no effect, but treatment with yellow (ca. 585 mμ) or red (ca. 650‐700 mμ) leads to substantial discharge 24 hr later. If, however, the yellow treatment is followed immediately with blue there is little or no discharge; but if the order of this treatment is reversed, a high level of discharge results. This is somewhat greater than that resulting from treatment with yellow light alone. If, following a yellow treatment there is an interval of several hours before a blue treatment, the blue has less effect in negating the action of the yellow light. It is shown that, although in the final light‐sensitive stages in development of the sporophore before it opens, yellow and red light are stimulatory but blue and green are not; in the phototropic response of the mature sporophores blue light is effective and yellow is not.

Effect of Blue and Yellow Light During the Later Developmental Stages of Sphaerobolus

When fruiting cultures of Sphaerobolus are transferred from continuous light to darkness the discharge of global masses continues for 1 day but then stops for the next few days. Experiments are reported in which this darkness is interrupted after 24 hr by brief (0.5-2 hr) treatment with light of different wavelengths and of equated low intensity (ca. 100 lux). Interruption by blue (ca. 448 mμ) or by green (ca. 500 mμ) light has no effect, but treatment with yellow (ca. 585 mμ) or red (ca. 650-700 mμ) leads to substantial discharge 24 hr later. If, however, the yellow treatment is followed immediately with blue there is little or no discharge; but if the order of this treatment is reversed, a high level of discharge results. This is somewhat greater than that resulting from treatment with yellow light alone. If, following a yellow treatment there is an interval of several hours before a blue treatment, the blue has less effect in negating the action of the yellow light. It is shown that, although in the final light-sensitive stages in development of the sporophore before it opens, yellow and red light are stimulatory but blue and green are not; in the phototropic response of the mature sporophores blue light is effective and yellow is not.

The morphogenetic movements at the lower surface of the blastodisc in salmonid embryos

AbstractPatterns of hitherto undescribed morphogenetic movements have been found in Salmo gairdneri and Salvelinus fontinalis by removing samples of blastodiscs from their yolk spheres at intervals of several hours and inspecting their lower surfaces. Before onset of epiboly, the former species usually produces no pregastrular subgerminal cavity, but the latter usually produces one or several, with wide variation. In both species the inner blastomeres consolidate from an earlier dispersed and migratory condition, forming a coherent flattened sheet 6 to 10 cells thick before active epiboly begins.As the first evidence of polarity in the salmomd embryo, one sector of the blastodisc becomes condensed and slightly thickened. Then a broad central area of the disc rapidly thins out as a result of two types of movement: (1) large numbers of cells disengage from the under surface of the condensed blastodisc, and they migrate away from the center as individuals and small groups; (2) the rest of the internal cells engage in a similar centrifugal movement toward the germ ring and the embryonic shield, but as a coherent sheet, sliding just within the cellular envelope.Some, perhaps all, of the disengaged cells of the first group are slowly gathered into the endoderm sheet. The coherent cells of the second group accumulate in germ ring and embryonic shield, where they become split temporarily into upper and lower sheets, the former adhering to the external layer, the cellular envelope, with which it forms the epiblast, and the latter associating with the disengaged cells as the hypoblast.The first internal sign of axis formation is a hitherto undescribed nubbin of cells attaching to the yolk syncytium at one sector on the inside of the blastodisc rim. The nubbin cells take no further part in the epibolic spread of the disc. It is suggested that they from an anchor for the later convergence movements from right and left, and that the whole pattern of movements from then on may be controlled by a gradient of increasing cell adhesiveness that spreads from them as a center. These nubbin cells have never been at the surface of the blastodisc. They neither invaginate nor migrate forward. They may represent the prechordal plate.

�ber die strahlungschemische Oxydation der Schwefligen S�ure

The radiation chemical oxidation of sulfurous acid was investigated in aqueous solution. For the preparation of the solution studied, a stream of sulfur dioxide and oxygen at constant composition was led into distilled water, which was irradiated with x rays immediately after the saturation concentration of sulfur dioxide was reached. Samples were taken at intervals of several hours from both the irradiated and unirradiated solutions and the sulfur dioxide was determined iodometrically and the sulfuric acid, after boiling off of the sulfur dioxide, with perchloric acid. The results are graphed. The calculated G value of the purely radiochemical formation of sulfuric is, for approximately 0.7 M sulfurous acid, surprisingly high at 205 plus or minus l2. (J.S.R.)

COEXISTENCE PHENOMENA IN THE CRITICAL REGION: V. THE GRAVITY EFFECT IN THE BINARY LIQUID SYSTEM ANILINE-CYCLOHEXANE FROM LIGHT SCATTERING

Transmittance measurements were used to investigate vertical concentration gradients, at temperatures slightly above the critical, in a binary liquid system. The gradients, which are predicted theoretically, did not begin to form during time intervals of several hours. It was found that a theoretical relation between transmittance and concentration gradient did not apply, even qualitatively, to the results obtained. The significance of these observations is discussed.

Changes in chromospheric fine structure from films taken by Lyot at the PIC DU Midi.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Changes in chromospheric fine structure from films taken by Lyot at the PIC du Midi. Lippincott, Sarah Lee Abstract While a guest at the Meudon Observatory, France, the author was given access to the sequences of photographs of solar activity on the disc taken by Lyot at the Pic du Midi in 1942. The purpose of the investigation was to explore the possibilities of obtaining a better insight into the small-scale changes of the chromospheric structure around a sunspot group which is characterized by fine dark line-structure, "fibriles," oriented in such a fashion as to suggest the presence of a magnetic field. The observations showing a center of activity on the disc, which were used in this investigation, consist of 1/40 second exposures taken at 30- second intervals for several hours on August 25, 1942. These films were obtained by Lyot in Ha radiation, using the Lyot filter mounted on the 38 cm refractor, which yields a solar diameter of 15 Cm. Prints enlarged 4.75 times from 65 negatives, chosen for their quality, were used for measurements. The upper limit of accuracy for the position of small chromospheric patterns which could be obtained under optimum observing conditions was estimated to be ~`;~. An average apparent velocity of the order of 7 km/ sec is found for the change in position of the ends of the fibriles projected on the disc. There seems to be no general translation with time, but rather a random fluctuation in position over a small area. It is difficult to determine the duration of the fibriles, for in certain instances one may disappear, while the same or a similar fibrile may appear in the same position some minutes later. This apparent disappearance and reappearance may be due to a number of causes: a) the fibrile momentarily sinking to a level in the chromosphere outside the range of the center of the Ha-radiation; b) the same local conditions being maintained to produce another fibrile with similar contours; c) or perhaps a spurious effect due to instrumental or seeing variations. During an interval of 45 minutes there is no observable change in the average orientation of the dark, fine-line structure in an arbitrarily chosen area of 25,000 km2 within the center of activity. All the measurements attempted are near the limit of resolution and should be accepted with caution. The optimum observing conditions must be maintained along with constant instrumentation, in order for such a study to be fully interpreted as fine structure motions. Sproul Observatory, Swarthmore College, Swarthmore, Pa. Publication: The Astronomical Journal Pub Date: June 1955 DOI: 10.1086/107197 Bibcode: 1955AJ.....60..168L full text sources ADS |

The radiographic appearances of hyaline disease of the lungs in the newborn.

Hyaline disease of the lungs in the newborn infant has received considerable attention in pediatric and pathologic circles, but a careful search of the radiologic literature has failed to reveal similar studies of a radiographic nature. In the case to be reported here, two successive radiographs of the chest at intervals of several hours were obtained in a newborn infant who died after thirty-two hours. This single case is presented in the hope that the description of the findings will stimulate others to carry out radiographic studies. It is possible (at least theoretically) that we are dealing with rather characteristic changes which, with the clinical findings, may contribute to the objective diagnosis of this condition during life. “Hyaline disease” of the lungs in the newborn infant is characterized by the presence of membranes which, lining the alveolar ducts or alveoli, prevent the proper oxygenation of the blood, so that the infant dies of asphyxia shortly after birth. This membrane has been variously called an “asphyxial” (1–3), “hyaline” (4–6) or “vernix” membrane (7, 8). Several theories as to the origin of the membrane have been offered. Johnson and Meyer (5) first reported (1925) the condition and attributed it to vernix caseosa inhaled with the amniotic fluid in utero. Farber and Wilson (4) also considered the membrane to be formed by the forced inhalation of amniotic sac contents. Actually, according to Farber and Sweet (9), the term “hyaline membrane” is a misnomer and the material has the appearance of vernix within which cornified epithelial cells are tightly pressed. The involved air sacs are usually more dilated than the surrounding alveoli. The membrane (with the exception of its amniotic sac contents) is similar to the hyaline membranes of influenza, Streptococcus hemolyticus and perhaps other pneumonias, a finding which first attracted the attention of Johnson and Meyer. Miller et al. (2, 10, 11), on the other hand, believe that these membranes represent a reaction to an injury to the epithelium of the air spaces, especially the bronchioles and alveolar ducts. The hyaline membrane is phagocytized by polymorphonuclear leukocytes and mononuclear cells. Miller and his associates also showed that there was no statistical relationship between the incidence of hyaline membrane formation and parity of the mother, mother's age, duration of labor, the interval between the rupture of the mother's membranes and the birth of the infant, the type of anesthesia or analgesics used, or the method of delivery including cesarean section. In no infant dying after ninety-six hours of age was this change in the lungs observed, but in infants weighing over 1,000 grams dying in the first forty-eight hours of life, there was a 65 per cent chance that a hyaline membrane would be found.

Appendix - The uptake of sodium and potassium by Bact. lactis aerogenes investigated by means of radioactive tracers

Radioactive sodium (Na 24 , half-life 14·8 hr.) and potassium (K 42 , half-life 12·4 hr.) were produced by A. E. R. E., Harwell, by neutron irradiation of the carbonates. The samples of sodium and potassium carbonate sent for irradiation were accurately weighed and sealed in small silica tubes. Standard solutions of the active material as chloride could then be made with a minimum of handling by breaking the tube into a beaker containing the calculated quantity of dilute hydrochloric acid and diluting to the required volume. Activities were measured using 10 ml. samples in a liquid-type Geiger counter. The electronic equipment was of conventional design and was built in the laboratory. In the first series of experiments inocula were transferred to a synthetic medium containing enough potassium to support a bacterial population of about 300 million cells/ml. Samples were withdrawn at intervals for several hours after the onset of the stationary phase. The cell count was measured and the potassium content of the medium determined from its activity after removal of the bacteria by centrifuging.

Observations on the value of small daily doses of phenothiazine for the control of trichostrongylosis in sheep

Summary Three preliminary experiments each involving two, pairs of twin lambs, and a confinnatory experiment in each of the two parts of which six pairs of twin lambs were used, were carried out to ascertain the effect of daily one gramme doses of phenothiazine on the rate of acquisition of infestation and on the worm burden of lambs kept at a constant rate of artificial infestation with Trichostrongylus axei . When a daily dose of one gramme of phenothiazine is given to lambs within a few minutes of a dose of infective trichostrongylid larvae the treatment does appear to, have some effect in reducing the number of inf ective larvae which develop to maturity. When there is an interval of several hours between the dose of phenothiazine and the dose of larvae each day, the treatment has no effect on the establishment of the larvae in the host. Daily doses of one gramme of phenothiazine have no effect in reducing the number of mature worms present in sheep. Daily doses of one gramme of phenothiazine do not prevent the development of severe parasitic gastritis in sheep continually exposed to infestation when there is an interval of several hours between the administration of the phenothiazine and the consumption of the larvae. Daily doses of one gramme of phenothiazine prevent the development of infective trichostrongylid larvae from eggs passed in the faeces of treated sheep. The effect of daily doses of one gramme of phenothiazine on the egg count in treated sheep was not constant. In some experiments no effect was observed, but in others the treated sheep had a lower egg count than the control group. It is suggested that the good results reported from the field from the use of phenothiazine-salt mixture in the control of parasitic gastritis must be referable to a reduction in the pasture larval count due to the property of small daily doses of phenothiazine of preventing the development of infective larvae from eggs passed in the fazces and not to an actual reduction in worm burden. It is probable, therefore, that good effects will be produced in lambs running with ewes which are kept on phenothiazine-salt treatment, but that adult sheep already infected are unlikely to benefit from such treatment. The efficacy of the treatment may be vitiated if a substantial number of the sheep refuse to take the medicament and the flock should be watched carefully to ascertain whether certain sheep habitually refuse the lick.

High T waves in the earliest stage of myocardial infarction

Twenty-seven instances of myocardial infarction were studied, in which the first electrocardiogram was taken as early as one and one-quarter hours, and not later than twelve hours, after the onset of symptoms. Follow-up tracings were obtained in all but two of these cases. In thirteen cases serial records, taken daily or at intervals of several hours, were available for study. In twenty-five cases the earliest electrocardiographic signs of infarction were high T waves, the majority of which became inverted in the healing stage of infarction. In most of the cases the high T waves were no longer present twenty-four hours after the attack. In five instances where the T waves persisted for several days, early mortality was as high as 60 per cent, as compared with 14 per cent in the cases where the high T waves underwent regression within twenty-four hours. The high T waves are thought to be part of the injury pattern. They were accompanied by abnormal elevations of S-T in twenty-one cases. In five instances elevation of S-T was either absent or within normal range. In one instance huge upright T waves were associated with marked depression of S-T. In the majority of the cases high T waves preceded the development of significant changes in the QRS complex. The latter usually appeared within twenty-four hours after the onset of symptoms, when the high T waves were already in the regressive stage. In one instance characteristic changes in QRS did not appear until six days after the attack, and in two instances they failed to develop at all. In five cases high T waves were not associated with abnormal elevation of S-T, nor with significant changes in QRS. Thus, they represented the leading diagnostic sign in the early stage of myocardial infarction.

Relation of Aeration to the Activity of Proliferation-Promoting Factors from Injured Cells

IN earlier tests of the proliferation-promoting activity of materials from injured cells (‘intercellular wound hormones’) in which yeast was used as the test organism1, the test cultures were grown in rocker tubes with continuous shaking2. This subjected them to appreciable aeration. In recent investigations of wound hormones, yeast was again employed as the test organism, but was cultured in stationary, cotton-plugged tubes suspended in a water bath. At intervals of several hours, the tubes were removed from the water bath, shaken, and the yeast population determined with a photo-electric densitometer. In these later experiments, all preparations failed to show appreciable activity, though they had been prepared strictly in accordance with previously used techniques1.

Apparatus for the Study of Comparative Transpiration

(WITH FIVE FIGURES) The quantitative study of the ecological factors of the habitat naturally leads to a similar investigation of the responses of the growth-forms to these elements of the habitat. Thus the investigation of the comparative evaporation of various local habitats has led to a complementary study of the comparative rates of transpiration of the plants occurring in them. In this latter work an effort has been made to obtain graphs of the hourly transpiration rates under a great variety of conditions of temperature, light, and humidity. For comparative purposes these data are being collected (i) by the synchronous exposure of several plants, and (2) by determining the ratios between the transpiration rate and the rate of evaporation from a standard vaporimeter. It is evident that for conducting a study of this kind, in which data regarding the effects of stimuli and latent periods are essential, the determination of the water losses by the method of weighing at intervals of several hours is, to say the least, unsatisfactory. A very perfect apparatus for the automatic weighing and recording of evaporation rates has been described by GANONG in this journal., For comparative purposes, however, several of these instruments are required, making the cost beyond the means of at least some laboratories. The following apparatus is essentially a modification of the Ganong transpirograph, developed for the special purpose of comparative work. Its efficiency, combined with its comparatively small cost, has made it seem worth describing in advance of the discussion of the data which are being obtained by its use. The complete outfit, as shown in fig. I, consists of a hygrothermograph, a chronograph, chemical balances, weight droppers,