Interval Of Hours Research Articles

Uncontrollable Rotational Motion of the Mir Orbital Station

The results of determining the rotational motion of the Mir orbital station are presented for four long segments of its unmanned uncontrolled flight in 1999–2000. The determination was carried out using the data of onboard measurements of the Earth's magnetic field intensity. These data, taken for a time interval of several hours, were jointly processed by the least squares method with the help of integration of the equations of station motion relative to its center of mass. As a result of this processing, the initial conditions of motion and the parameters of the mathematical model used were evaluated. The technique of processing is verified using the telemetry data on angular velocity of the station and its attitude parameters. Two types of motion were applied on the investigated segments. One of them (three segments) presents a rotation around the axis of the minimum moment of inertia. This axis executes small oscillations with respect to a normal to the orbit plane. Such a motion was used for the first time on domestic manned orbital complexes. The second type of motion begins with a biaxial rotation which, in a few weeks, goes over into a motion very similar to the rotation around the normal to the orbit plane, but around the axis of the maximum moment of inertia.

Complex traumatic dissection of right vertebral and bilateral carotid arteries: a case report and literature review

A 27-year-old female motorcycle passenger was admitted with bruises and concussion after a motor-vehicle accident. After a lucid interval of several hours she became stuporous and progressed to an acute comatose state. Computed tomography demonstrated extensive cerebral ischaemia in the territory of the right middle cerebral artery. Angiography after transfer to the authors' hospital revealed dissections of both carotid arteries and of the right vertebral artery. The patient underwent surgical reconstruction of the left internal carotid artery with saphenous vein. The management of this patient is discussed and the literature reviewed.

Complex Traumatic Dissection of Right Vertebral and Bilateral Carotid Arteries: A Case Report and Literature Review

A 27-year-old female motorcycle passenger was admitted with bruises and concussion after a motor-vehicle accident. After a lucid interval of several hours she became stuporous and progressed to an acute comatose state. Computed tomography demonstrated extensive cerebral ischaemia in the territory of the right middle cerebral artery. Angiography after transfer to the authors' hospital revealed dissections of both carotid arteries and of the right vertebral artery. The patient underwent surgical reconstruction of the left internal carotid artery with saphenous vein. The management of this patient is discussed and the literature reviewed.

Radiation‐induced apoptosis in human tumor cell lines: Adaptive response and split‐dose effect

Irradiation of human ovarian carcinoma cells (OVCAR 3) and myeloma cells (RPMI 8226) with graded doses of 137Cs-γ-rays led to a 35–40% increase in time-dependent apoptosis 72 hr after 6–8 Gy irradiation. Large individual variations in sensitivity to radiation-induced apoptosis were noted in human lymphocytes obtained from 5 donors. Pretreatment of OVCAR 3 and RPMI 8226 cells with 0.01 Gy increased their resistance to apoptosis after subsequent 6 Gy irradiation several hours or 48 and 72 hr later. A dose of 4 or 8 Gy given in 2 equal fractions at an interval of a few hours produced a low level of apoptosis compared to that resulting from a single administration of the same total dose. Adaptive response was demonstrated in 2 out of 3 samples of human lymphocytes isolated from different donors, and no split-dose effect for apoptosis was noted in 2 other donors. In split-dose experiments, there was no correlation between the sensitivity of cells to apoptosis and their position in the cell cycle, after the first half-dose. No G1 block was observed in irradiated cell lines. Adaptive response and split-dose effect were prevented by 3-aminobenzamide and okadaic acid which inhibit poly(ADP-ribose)polymerase and protein phosphatase, respectively. These results imply a common mechanism for acquired resistance to radiation-induced apoptosis in adaptive response and the split-dose effect. Int. J. Cancer 77:76–81, 1998.© 1998 Wiley-Liss, Inc.

Radiation-induced apoptosis in human tumor cell lines: adaptive response and split-dose effect.

Irradiation of human ovarian carcinoma cells (OVCAR 3) and myeloma cells (RPMI 8226) with graded doses of 137Cs-gamma-rays led to a 35-40% increase in time-dependent apoptosis 72 hr after 6-8 Gy irradiation. Large individual variations in sensitivity to radiation-induced apoptosis were noted in human lymphocytes obtained from 5 donors. Pretreatment of OVCAR 3 and RPMI 8226 cells with 0.01 Gy increased their resistance to apoptosis after subsequent 6 Gy irradiation several hours or 48 and 72 hr later. A dose of 4 or 8 Gy given in 2 equal fractions at an interval of a few hours produced a low level of apoptosis compared to that resulting from a single administration of the same total dose. Adaptive response was demonstrated in 2 out of 3 samples of human lymphocytes isolated from different donors, and no split-dose effect for apoptosis was noted in 2 other donors. In split-dose experiments, there was no correlation between the sensitivity of cells to apoptosis and their position in the cell cycle, after the first half-dose. No G1 block was observed in irradiated cell lines. Adaptive response and split-dose effect were prevented by 3-aminobenzamide and okadaic acid which inhibit poly(ADP-ribose)polymerase and protein phosphatase, respectively. These results imply a common mechanism for acquired resistance to radiation-induced apoptosis in adaptive response and the split-dose effect.

Irregular Geomagnetic Pulsations within 0.5-5 Hz Range at L-3-4.

At the Yakut chain stations in the subauroral zone (L ∼ 3-4) Pil pulsations within 0.5-5 Hz frequency range have been revealed by the active band-pass filters. They are observed during intense geomagnetic disturbances (K≥ 4) in the interval of night-dawn hours on a background of Pi 1 B and Pi 1 C, and can be accompaniedby auroral pulsations in this frequency range. Main spatial-temporal characteristics of the high-frequency geomagnetic pulsations are presented and their possible sources are discussed.

Sucrose Transport into, and Unloading from, the Seed Coat of Empty Ovules of Pisum sativum over Time-Spans Greater than Three Hours

Summary This paper discusses whether assimilate transport into seed coats of surgically modified ovules deteriorates over time-spans greater than about 3 h. In experiments with fruits of pea ( Pisum sativum L.), several hours before the start of a pulse-labelling procedure, two empty ovules were prepared in each fruit. Subsequently, after a time interval of several hours, two other empty ovules were prepared in each fruit. Immediately after this procedure, [ 14 C]sucrose was fed to the leaf subtending the fruiting node. During a pulse-chase period (80-360 min), transport of 14 C into ovules operated several hours before the start of a pulse-labelling procedure was only slightly reduced, in comparison with transport of 14 C into ovules operated directly before the start of a pulse-labelling procedure. Data on the release of 14 C-solutes from the seed coat also supported the view that, with respect to sucrose transport into developing ovules, surgically modified ovules can function almost normally over time-spans of at least 6-8 h.

Mating induces puberty in the female musk shrew.

Female musk shrews (Suncus murinus), lacking a behavioral estrous cycle, engage in copulatory behavior whenever tested; even during pregnancy, sexual activity can be displayed. Studies suggest that protracted sexual behavior has a functional significance in this species. Virgin females receiving a series of ejaculations over the course of several days are more likely to ovulate and subsequently deliver than animals given the same number of ejaculations over an interval of a few hours. After the virgin mating only one third of the ovaries placed in culture exhibit increased steroidogenesis. In the present set of studies, the hypothesis that the virgin mating induces the onset of puberty, in a manner similar to that in which male-related pheromones induce estrous in rodents, was tested. On the basis of gestational lengths it is evident that females mated three times (on Days 0, 4, and 8) became pregnant in the vast majority of cases as a result of the second and third matings. When the first and second matings were separated by 25 days, 82% of females ovulated in response to the second mating; less than one third of females mated only once ovulated. Finally females were housed across a screen from males, exposed to male urine, or housed alone prior to the virgin mating. In none of these cases did pre-exposure to male-related cues increase ovulation rates in response to the virgin mating. The results show that the virgin mating primes the neuroendocrine system in such a way that the pubertal ovulation can occur in response to subsequent mating.(ABSTRACT TRUNCATED AT 250 WORDS)

Low temperature behaviour of ion-beam-grown polymer-metal composite thin films

Polymer-metal granular thin films were grown by simultaneous ion beam sputtering from a composite target. Morphological analysis performed by transmission electron microscopy shows their granular fine structure. The samples' ageing process was monitored over an interval of many hours after the film deposition. A detailed study of the resistance vs. temperature behaviour was performed over the range 12–300 K; current-voltage measurements as a function of temperature are also reported. An unusual ln( R) ∞ T −1 dependence was found at low temperature. This behaviour is explained with theoretical arguments based on percolation theory.

Bioavailability estimation by semisimultaneous drug administration: A Monte Carlo simulation study

The performance of a novel method for determination of drug absorption characteristics was evaluated by Monte Carlo simulations. In bioavailability studies with use of this method, the test and the reference doses are administered within a time interval of hours. Estimates of bioavailability are obtained by fitting an appropriate model to the concentration-time profile, which in its terminal portion is thus the summed concentration of the two doses. Drugs with different properties, mimicked by varying the kinetic rate constants (ka, lambda 1 and lambda 2), and experimental designs with different sets of conditions regarding the interval between doses, dose ratio, dose order, and duration of sampling, were simulated to determine what factors govern parameter estimation. The absorption characteristics of the simulated drugs could be adequately determined in experiments lasting for 12 hr or less, provided that a proper design was used. Fitting of a simpler or a more complex disposition model produced estimates with similar accuracy and precision to those noted with the true model. For some conditions the use of an improper absorption model resulted in slightly reduced accuracy, but as these fits were poor there was a clear need to try other models. In another set of simulations the use of the proposed method to assess the relative availability of two extravascular doses was evaluated. The relative rate and extent of absorption could be estimated with good precision for two formulations exhibiting a rapid to moderate rate of absorption.

Journal of Bone and Mineral Research

To assess whether an interval of a few hours would be advisable between an intake of sodium fluoride (NaF) and that of calcium salts when treating osteoporotic patients with vertebral collapse, we carried out three pharmacokinetic studies in 12 healthy fasting volunteer subjects to compare the fluoride bioavailability provided by NaF alone and NaF combined with two calcium salts. The results were as follows: (1) When NaF is accompanied by calcium, the fluoride peak level is lower and delayed. (2) Fluoride absorption varied greatly among individuals in both experiments, but none of the 6 subjects proved to be nonabsorbers. (3) The areas under the curves obtained with each of the three preparations were not significantly different, but 24-h urinary fluoride was significantly lower in volunteers receiving simultaneously NaF and calcium salts than in volunteers receiving only NaF.

The responses of individual males in an isolated population of Glossina morsitans morsitans Westwood (Diptera: Glossinidae) to pheromone-baited decoy ‘females’

AbstractThe responses of individually marked males of Glossina morsitans morsitans Westwood to decoys (9 × 3-mm rectangles of 2-mm-thick brushed nylon) baited with sex pheromone (15,19,23-trimethylheptatriacontane) were studied after their release onto an island in Lake Kariba, Zimbabwe. Some 45–60% of resighted flies were seen on decoys, the percentage being greater for flies released at an older age. For flies released on emergence, the mean age at first contact with decoys on a static screen was 6.6 days, an average of four days later than their first observed contact with a bait ox. There was great variability in the response towards decoys on successive contacts. In general, the intensity of the responses to decoys in the first minute after contact (the ‘pre-copulatory’ responses) decreased from one enounter to the next in a single 1–2-h observation session, but were restored to high levels after an interval of several hours. The intensity of responses towards decoys after this initial period (the ‘copulatory’ responses) were not affected by previous contacts. Neither previous sexual experience nor age at first contact affected the durations of response on decoys. There were no differences between the responses of wild flies and those from a laboratory colony. The results are discussed in relation to the use of decoys with chemosterilant for tsetse autosterilization. Over 60% of flies contacting decoys did so more than once, which would increase, cumulatively, the chances of their being sterilized.

Mixtures of Monogalactosyldiacylglycerols in Water Have a Persistent Liquid Crystalline Phase

Abstract Phase structures and transitions were monitored in real time for a fully hydrated 1:1 mixture of saturated and native monogalactosyldiacylglycerol using an x-ray beamline at the Daresbury (U.K.) Synchrotron Lab. A single phase characterized by a single diffraction peak at ca. 3.18 nm is observed over all temperatures studied. The initial crystalline acyl chain phase is equivalent to the LC2 subcell packing observed in fully saturated mixtures. The transition from the LC2 to the liquid crystalline phase may involve the appearance of intermediate states. Subsequent temperature changes do not produce a change in the liquid crystalline acyl chain phase over a time interval of hours.

The Active Radio Star HD 36705

AbstractThe single G8V active chromosphere star HD36705 (AB Dor) was observed at 8.4 GHz with the Parkes 64 m telescope during three observing sessions involving a total of 21 days in the interval 1985 December to 1986 February. Subsequent photometric observations were made of the star with the 0.25 m and 0.45 m telescopes of the Monash Observatory in 1986 March-April. Two strong radio flares, each lasting three days, were detected; they yielded peak radio powers ofP8.4≈4×109W Hz-1, comparable with the microwave power emitted by the RS CVn binaries. Significant circular polarization of 13% left-hand was measured on only one of the six active days. The 8.4 GHz flux density showed smooth variation over an interval of several hours, consistent with the flare source being partly occulted by the stellar disk as the star rotated. When all the radio data was phase-binned using the known rotation period of 0.514 day we found two radio maxima corresponding to radio sources at stellar longitudes ~180° apart. The subsequent photometric data showed intensity variations that were consistent with the starspots at the same approximate longitudes. We thus interpret our radio curve as showing the presence of comparatively small (<0.5 D*) radio sources in the corona above the star spots. The upper limit to source diameter gives a peak brightness temperature ≥2×l010K, which can be achieved by gyro-synchrotron emission only if the source is optically thick and the electrons, with average energy ~ 2 MeV, have a hard energy spectrum. The observed radiation can be due only to very high harmonics of the gyro-frequency, leading to an estimate for the magnetic field strength of ~30G.

Structural aspects of ischemic brain damage.

The structural changes during cerebal ischemia are reviewed. In the acute phase the neurons may show either pale or dark type of ischemic injury. The former is usually associated with complete ischemia and the structural alterations are fairly inconspicious, while the latter is seen in incomplete ischemia or ischemia with recirculation and is characterized by shrinkage of neurons with extensive mitochondrial swelling and astrocytic edema. Both types of injury may be irreversible, but long post-ischemic period is usually necessary to see the final outcome of the insult, all the more since the neurons may not die until after a free postischemic interval (even with resumed function) of several hours to days. The delayed death is preceded by peculiar proliferation of cytoplasmic membranes before the doomed neurons become shrunken and disintegrate. This "maturation phenomenon" or "delayed neuronal death" is understandably important since it suggests that a longer postischemic interval for therapeutic interventions may exist. Several factors both during and after the ischemic insult can modify the changes and affect the severity of the damager among the most important ones are the degree of lactic acidosis during the ischemic period, as well as the characteristics of the neurons, since excitoxic damage by transmitter substances released by the ischemic insult has been suggested to be responsible for the delayed neuronal death.

Trousseau's syndrome. Devastating coagulopathy in the absence of heparin

Two patients with Trousseau's syndrome experienced frequently recurring concomitant arterial and venous thrombotic events that resulted in sequential amputation and loss of the lower extremities. Serial examination of the blood in the patients demonstrated that these devastating thrombotic events were preceded by severe disseminated intravascular coagulopathy that occurred within an Interval of a few hours. Warfarin therapy was without effect in preventing the occurrence of these events. Both patients demonstrated the absolute need for intravenous heparin, which effectively prevented the thrombotic events; when it was discontinued, the immediate consequences were disastrous and resulted in death. Techniques for long-term outpatient heparin therapy are discussed.

Gravitational Character of Cold Surges during Winter MONEX

Abstract The surface pressure, temperature, dew point and wind data over the South China Sea and vicinity during Winter MONEX are examined to determine the timing of the passage of cold surges at various reporting stations. It is found that for more than half of the surge cases during Winter MONEX, a surge occurs in two stages separated by a time interval of several hours to approximately one day. The first stage is often characterized by a significant rise in pressure, while the second stage by a sharp decrease in dew point temperature. Freshening of surface winds may accompany either or both stages. The time separation between the two stages is relatively short at the upstream stations but generally long at the downstream stations. The second stage is associated with a frontal passage. On the other hand, the first stage is not clearly associated with any significant synoptic events. From its very fast propagation speed which increases with an inferred depth scale, and an increase in the local cross-isob...

Nerve growth factor may stimulate either division or differentiation of cloned C1300 neuroblastoma cells in serum-free cultures.

Two clones of mouse C1300 neuroblastoma cells (clones NB1R and NB6R) bind mouse 2.5S Nerve Growth Factor (NGF) in vitro. The ligand is then capped and internalized by the cells. This step requires active cell processing. In serum-free or low serum conditions, clear effects of NGF are seen with both clones. Cultured NB1R cells are stimulated, after a lag interval of a few hours, to synthesize DNA and to proliferate, whereas NB6R cells are stimulated to cell differentiation and maintain viability under these conditions much longer than similar cultures in the absence of NGF. Stimulation of clone NB1R occurs within an optimal dose concentration of the same order as that used in the Levi-Montalcini bioassay with 8-day-old chick embryo-sensitive ganglia; the effects on clone NB6R, however, need higher NGF concentrations. Both effects are protein-specific since they are inhibited in the presence of added anti-NGF antibodies. This system could provide a convenient means to study the control of cell division in susceptible malignant neuroblastoma clones and to correlate NGF binding to receptors and biological activity.

Effect of additional protein or methionine and threonine on tyrosine catabolism in rats fed diets high in tyrosine.

The supplementation of additional protein or methionine and threonine to a high tyrosinc-low protein diet has previously been shown to prevent the tyrosine toxicity. To elucidate the mechanism, studies were performed on the effect of these supplements on the capacity to oxidize excessive tyrosine. Male weanling rats were ad libitum fed a 10% casein diet containing 5% tyrosine with and without extra casein or methionine plus threonine for 7 days, then animals were injected intraperitoneally with l-tyrosine-U-14C and the oxidation rate to 14CO2 determined in vivo at an interval of several hours throughout a 24-hour period. The addition of extra casein or methionine and threonine to the high tyrosine diet enhanced the ability of tyrosine oxidation, and decreased the radioactivities of the TCA-soluble fractions in plasma, liver and muscle. A high level of free tyrosine in blood and tissues was also lowered by the addition of these supplements. The diurnal chenges in free tyrosine concentration of various tiss...

Ionospheric spread- F at Huancayo, sunspot activity and geomagnetic activity

A superposed-epoch method is used to investigate the occurrence of spread- F at Huancayo relative to days of high sunspot activity and also relative to days of high geomagnetic activity. A good correlation is found between days of high A p , index and high spread- F occurrence for a pre-sunrise interval of a few hours. When 3-hourly K p indices are used they show a peak value approximately 6 hr prior to an above-average occurrence of spread- F. It is suggested that this pre-sunrise spread- F is associated with ionospheric height rises which are produced by travelling disturbances, initiated in polar regions at times of high geomagnetic activity.