Half Of Day Research Articles

Space Weather Research by means of High Mountain Alma-Ata Neutron Monitor

For multi-wavelength investigations of solar activity it may be used the intensity of cosmic ray, registered by means of neutron monitors, because the variations of cosmic ray intensity are very sensitive for local and global solar activity changes. It is important also for space weather investigation. So, we use special indices characterized the level of cosmic ray activity and some peculiarities of the space weather (Belov et al. 1999). To apply the approach, already used for cosmic ray activity calculation, to the single detector data, we have to study daily run of the counting rate. During quiet days we have in the neutron monitor data sinuslike daily variation. The characteristics of the normal for the current period anisotropy and location of the station define it. Thus, on Alma-Ata station counting rate mainly increases on the first half of day and decreases on the second one. The density changing and the anomalous anisotropy behavior lead to distortion of daily run, and the greater is of cosmic ray disturbance, the more is distortion. Let in hour t the variation of the counting rate relatively to daily mean is ∆(t), and its hourly change is d(t )=∆ (t) − ∆(t − 1). Comparing this value with the same for the quiet period d0(t), we can find hourly indices of cosmic ray disturbance for the single station (for high altitude Alma-Ata station-CRAaatb )a s: CRAaatb = b|d(t) − d0(t)|s −1 − a. The problem of the random variations on using indices from a single station becomes more pressing than for global CRA-indices. The use of cosmic ray detector with high counting rate as high altitude Alma-Ata neutron monitor is preferable here. The AlmaAta high altitude neutron monitor has a favorable location and very good statistics (1200 counts per second) to detect different cosmic ray effects conditioned by the solar activity and space weather. The combination of geomagnetic cut-off rigidity (6.7 GV) and high altitude (3340 m above sea level) makes our station enable to record ground level enhancements (GLE) for the events where maximal rigidity of the protons exceeds 6.7 GV. CRA indices for Alma-Ata station were calculated with s=0.09%, b=3, a=1. The local cosmic ray activity indices (CRA) were calculated for every hour within the period of 1971-1994 on the base of cosmic ray density, obtained by means of high mountain Alma-Ata neutron monitor. The behavior of cosmic ray activity indices reveals not only the greatest cosmic ray disturbances but the smaller cosmic ray variation as well, because these indices are sensitive to heliospheric effects (Figure 1-the left plot). The data from a single neutron monitor has a decisive advantage: these data allow estimating of cosmic ray disturbance in the real time. In order to analyse interplanetary and geo-space situation during of dangerous periods of space environment we use real-time observations of cosmic ray intensity in 1-minute regime of accumulation. Besides that we calculate hour cosmic ray activity indices in real time. Observations of energetic particles and galactic

Numerical Simulation of the Ring Current: Review

Numerical simulation of the terrestrial ring current is reviewed. After mentioning ‘modules’ which are needed to be taken into consideration in a ring current simulation, we discuss growth and decay of the ring current. At least four different paradigms have been proposed to account for the ring current development in the past forty years, i.e., the convection paradigm, the substorm paradigm, the diffusion paradigm, and the ionosphere paradigm. As for the proton ring current, a simulation under the convection paradigm gives reasonable results which are in fair agreement with observations with respect to the Dst variation as well as the radial and longitudinal energy density variation of protons when the convection electric field depending on solar wind parameters is given. The proton energy density is observed to be enhanced (weakened) on the nightside, and be weakened (enhanced) near noon during a storm main phase (recovery phase). This characteristic is probably understood to mean that a large-scale and long-standing electric field dominates other electric fields during the storm main phase, e.g., a locally induced electric field (the substorm paradigm) and a highly fluctuated electric field (the diffusion paradigm). The declining of the ring current is shown to be triggered by the decrease in the convection electric field at the beginning of a storm recovery phase, but the decrease in the convection electric field hardly contributes the decay of the ring current. The charge exchange or other loss processes is needed for the substantial decay of it. An ultimate decay rate (several hours) is achieved when the strong diffusion takes place, or when the plasma sheet density drastically decreases while the charge exchange is estimated to provide rather slow decay (a half of day). Diagnosis tools for investigating the ring current, which are expected to bring us a new insight, are proposed in the latter section.

Urgent Joint Observation of Aftershocks of the 1995 Hyogo-ken Nanbu Earthquake.

A disastrous earthquake with a magnitude of 7.2 hit the southern part of Hyogo Prefecture on January 17, 1995. The mainshock was located on an active fault of the Arima-Takatsuki-Rokko fault system. Its focal mechanism was consistent with a right-lateral strike-slip fault trending N40°E. Three days after the occurrence of the mainshock, we started to install a highly dense seismic array in and around the fault area of the quake. Two permanent regional seismic networks of more than 30 stations covered the entire area of 200 km × 200 km. The temporarily installed array of 27 stations spanned the fault area of 15 km × 50 km. All data were telemetered to a temporary observation center at Uji. We located about 3, 100 aftershocks in real time for 1 month using an Internet connection between seismic networks. The aftershock area extended 70 km trending northeast to southwest. Hypocenters determined by the network were delivered automatically through the Internet. We found that the aftershock distribution was heterogeneous in space and time: seven clusters of hypocenters were identified and temporary variation in the rate of occurrence of aftershocks had a periodic component with periods of a half of day, 1 day, and 3 days, that are superimposed on decaying of the rate following Omori's law.

Effect of maternal paraquat administration on the fetal ductus arteriosus in the rat.

The ductus arteriosus (DA) in the fetal rat was calibrated using a whole-body freezing method, 3 hr after maternal treatment with paraquat at a dose of 25 mg/kg of body weight on days 19-21 of gestation. On days 20 and 21, the DA was significantly constricted. The DA was also significantly constricted on day 19 2/3 but not on day 19 1/2. It is concluded that paraquat has a constrictive effect on the DA and that the onset of this effect occurs in the first half of day 19 of gestation.

Cyclic Variations in Intraluminal Pressure in the Isthmus of the Oviduct in Unrestrained Gilts

Cyclic variations in intraluminal pressure in the isthmus of the oviduct in unrestrained gilts were observed. During proestrus and through the first day of oestrus, base pressure and total pressure increased reaching a high pressure on the second half of day 1 (first day of standing oestrus) after which a decrease was seen with a low base pressure recorded on the second half of day 3 and a low total pressure appearing on the second half of day 3 lasting through day 4. The frequency of the phasic pressure fluctuations in the isthmus also increased during proestrus and reached a high value on the first half of day 2. The frequency then declined to a low value on day 4. The pattern in which the phasic pressure fluctuations were arranged changed from predominantly wavy during proestrus and through the first half of day 2 to progressively more irregular in appearance after day 2. Outbursts of increased intraluminal pressure with varying propagation directions occurred with a fairly high frequency from the second half of day 2 and through day 3.

Onset of the Constrictive Effect of Indomethacin on the Ductus arteriosus in Fetal Rats

The time of onset of the constrictive effect of indomethacin on the ductus arteriosus (DA) in fetal rats was assessed by measurement of the caliber of the DA after maternal treatment with indomethacin on days 19-21 of gestation. The day following overnight mating was regarded as day 0 of gestation. Observation was performed by direct exposure of the DA by hand shaving of intact frozen fetuses. On days 20 and 21, the DA was significantly constricted 3 h after maternal treatment with 1 mg/kg of indomethacin. When the DA was examined at 19 1/2 and 19 2/3 days of gestation (3 h after indomethacin exposure), it was significantly constricted at 19 2/3 days but not at 19 1/2 days. Higher doses of indomethacin (10 and 100 mg/kg) induced a significant constriction of the DA at day 19 1/2, but not at the beginning of the same day (1.00 a.m.). These results suggest that the onset of the susceptibility of the DA to the constrictive effect of indomethacin occurs in the first half of day 19 of gestation.

Clinical use of visual evoked potentials: [formula omitted] (Loyola University of Chicago, Chicago, IL 60153, U.S.A.)

This study shows that the neurons of the entopeduncular nucleus are derived from a longitudinal slab of isochronically generated neurons on day 11 and 15 h of gestation. Many neurons of this longitudinal slab which we have named the basal forebrain cell column, originate from an ependymal matrix closely associated with the ventral diencephalic sulcus and later become associated with the basal forebrain bundle. Other neurons also originate from the ependymal matrix at the site of emergence of the optic recess and keep close relationships with the optic chiasma through the following stages of development to form the retrochiasmatic nucleus. During the second half of day 12 of gestation, the mantle layer of the forebrain shows an early zone of differentiation along its ventrolateral aspect. At this stage, the basal forebrain cell column extends unbroken from the tuberculum posterius to the chiasmatic plate primordium (site of generation of the retrochiasmatic nucleus). At the level of the caudal aspect of the optic stalk however, the basal forebrain cell column divides in two limbs associated to the ventral and dorsal edges of the optic stalk as it emerges from the forebrain. On day 14 of gestation, the neurons of the dorsal limb of the basal forebrain cell column occupy the mantle layer of the neural tube at least as far rostrally as the ventricular elevation in front of the optic stalk in the floor of the foramen of Monro. The neurons derived from the basal forebrain cell column begin breaking up into a series of more definite nuclei at later stages of development.The main finding of this study is the disclosure of the fact that the entopeduncular nucleus as well as other cell groups as dissimilar as the lateral preoptic area, the central, medial and anterior cortical amygdaloid complex and neurons of the dorsal hypothalamic area appear to be embryologically related, as they are all derived from a common longitudinal slab of the matrix of the forebrain.

Diurnal patterns of canopy photosynthesis, evapotranspiration and water use efficiency in chickpea (Cicer arietinum L.) under field conditions

Diurnal changes in net photosynthetic rate (PN), evapotranspiration rate (ET) and water use efficiency (WUE=PN/ET) of field grown chickpea (Cicer arietinum) L. cv. H-355 were studied from the vegetative phase through maturirty at Haryana Agricultural University Farm, Hissar, India. The maximum photosynthetic rate (PN max) increased from the initial vegetative phase to pod formation and declined at a rapid rate from pod filling to maturity. The response of PN to photosynthetic photon flux density (PPFD) (400-700 nm) was temperature-dependent during the day, i.e. on cool days the PN rates were lower for certain quanta of PPFD during the first half than during the second half of day, and vice versa on warm days. ET was affected both by crop cover and evaporative demand up to flowering, but thereafter it was independent of crop cover and followed the course of evaporative demand. ET was related to air temperature during the day while PN was related to PPFD. There was a lag of two to three hours between PNmax (around noon) and ETmax (around 2 p.m.). WUE increased from the vegetative stage through flowering but decreased thereafter to maturity.

Histogenesis at the level of the basal forebrain: The entopeduncular nucleus

This study shows that the neurons of the entopeduncular nucleus are derived from a longitudinal slab of isochronically generated neurons on day 11 and 15 h of gestation. Many neurons of this longitudinal slab which we have named the basal forebrain cell column, originate from an ependymal matrix closely associated with the ventral diencephalic sulcus and later become associated with the basal forebrain bundle. Other neurons also originate from the ependymal matrix at the site of emergence of the optic recess and keep close relationships with the optic chiasma through the following stages of development to form the retrochiasmatic nucleus. During the second half of day 12 of gestation, the mantle layer of the forebrain shows an early zone of differentiation along its ventrolateral aspect. At this stage, the basal forebrain cell column extends unbroken from the tuberculum posterius to the chiasmatic plate primordium (site of generation of the retrochiasmatic nucleus). At the level of the caudal aspect of the optic stalk however, the basal forebrain cell column divides in two limbs associated to the ventral and dorsal edges of the optic stalk as it emerges from the forebrain. On day 14 of gestation, the neurons of the dorsal limb of the basal forebrain cell column occupy the mantle layer of the neural tube at least as far rostrally as the ventricular elevation in front of the optic stalk in the floor of the foramen of Monro. The neurons derived from the basal forebrain cell column begin breaking up into a series of more definite nuclei at later stages of development. The main finding of this study is the disclosure of the fact that the entopeduncular nucleus as well as other cell groups as dissimilar as the lateral preoptic area, the central, medial and anterior cortical amygdaloid complex and neurons of the dorsal hypothalamic area appear to be embryologically related, as they are all derived from a common longitudinal slab of the matrix of the forebrain.