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Copyright of Rechtsmedizin is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Confirmatory tests for the diagnosis of brain death in addition to clinical findings may shorten observation time required in some countries and may add certainty to the diagnosis under specific circumstances. The practicability of Gadolinium-enhanced magnetic resonance angiography to confirm cerebral circulatory arrest was assessed after the diagnosis of brain death in 15 patients using a 1.5 Tesla MRI scanner. In all 15 patients extracranial blood flow distal to the external carotid arteries was undisturbed. In 14 patients no contrast medium was noted within intracerebral vessels above the proximal level of the intracerebral arteries. In one patient more distal segments of the anterior and middle cerebral arteries (A3 and M3) were filled with contrast medium. Gadolinium-enhanced MRA may be considered conclusive evidence of cerebral circulatory arrest, when major intracranial vessels fail to fill with contrast medium while extracranial vessels show normal blood flow. [ABSTRACT FROM AUTHOR]

We present a detailed model of stray-light suppression in the spectrometer channels of the Ultraviolet Coronagraph Spectrometer (UVCS) on the SOHO spacecraft. The control of diffracted and scattered stray light from the bright solar disk is one of the most important tasks of a coronagraph. We compute the fractions of light that diffract past the UVCS external occulter and non-specularly pass into the spectrometer slit. The diffracted component of the stray light depends on the finite aperture of the primary mirror and on its figure. The amount of non-specular scattering depends mainly on the micro-roughness of the mirror. For reasonable choices of these quantities, the modeled stray-light fraction agrees well with measurements of stray light made both in the laboratory and during the UVCS mission. The models were constructed for the bright H i Lyα emission line, but they are applicable to other spectral lines as well. [ABSTRACT FROM AUTHOR]

Coordination of the respiratory rhythm with the rhythm of limb movements has often been observed during rhythmical exercise (e.g. in locomotion). It is usually associated with changes in the respiratory time course, but not in the locomotor rhythm. Therefore, we hypothesised that in walking, the extent of coordination-related changes (CRC) in respiratory parameters would increase with closer coordination. With respect to the controversially discussed question of a possible energetic advantage due to coordination, we devoted particular interest to the CRC in oxygen uptake (VO2). In addition, we investigated the incidence and the extent of CRC in the stepping rhythm. We examined 18 volunteers walking on a treadmill at three different workload levels, which were adjusted by altering either the velocity or slope of the treadmill. Each walking test was carried out twice, once with spontaneous breathing and once with breathing paced by a step-related acoustic signal to enhance the coordination between breathing and walking. No correlation was found between the CRC in the analysed parameters and the degree of coordination. However, the extent of CRC of ventilation and VO2 decreased with increasing workload. With the transition to coordination, increases and decreases of VO2 occurred about equally often. From this we conclude that energetic economisation in walking, as reflected by a reduction in VO2, is rather a side-effect of coordination, and is probably due to a more precise regulation of the breathing pattern. The economisation was more pronounced at higher work loads than at lower work loads. Our results revealed that coordination is also associated with changes in the stepping rate, which occurred more frequently when the variability of breathing was restricted by acoustic pacing of the breathing rhythm. This finding suggests that the choice of walking rhythm is not completely free, but can be influenced by the breathing rhythm. CRC in the walking rhythm might contribute to the avoidance of excessive CRC in the respiratory time course, which would entail an inefficient breathing pattern and thus, an energetic disadvantage. [ABSTRACT FROM AUTHOR]

In order to investigate whether vascular endothelial growth factor (VEGF) and inflammatory pathways are activated during acute hypobaric hypoxia in subjects who are susceptible to high-altitude pulmonary oedema (HAPE-S), seven HAPE-S and five control subjects were exposed to simulated altitude corresponding to 4000 m in a hypobaric chamber for 1 day. Peripheral venous blood was taken at 450 m (Zürich level) and at 4000 m, and levels of erythropoietin (EPO), VEGF, interleukin-6 (IL-6) and the acute-phase proteins complement C3 (C3), α1-antitrypsin (α1AT), transferrin (Tf ) and C-reactive protein (CRP) were measured. Peripheral arterial oxygen saturation (SaO2) was recorded. Chest radiography was performed before and immediately after the experiment. EPO increased during altitude exposure, correlating with SaO2, in both groups (r = -0.86, P < 0.001). Venous serum VEGF did not show any elevation despite a marked decrease in SaO2 in the HAPE-S subjects [mean (SD) HAPE-S: 69.6 (9.1)%; controls: 78.7 (5.2)%]. C3 and α1AT levels increased in HAPE-S during hypobaric hypoxia [from 0.94 (0.11) g/l to 1.07 (0.13) g/l, and from 1.16 (0.08) g/l to 1.49 (0.27) g/l, respectively; P < 0.05], but remained within the clinical reference ranges. No significant elevations of IL-6, Tf or CRP were observed in either group. The post-exposure chest radiography revealed no signs of oedema. We conclude that VEGF is not up-regulated in HAPE-S and thus does not seem to increase critically pulmonary vascular permeability during the 1st day at high altitude. Furthermore, our data provide evidence against a clinically relevant inflammation in the initial phase of exposure to hypoxia in HAPE-S, although C3 and α1AT are mildly induced. [ABSTRACT FROM AUTHOR]

We constrain coronal outflow velocity solutions, resolved along the line-of-sight, by using Doppler dimming models of H I Lyman alpha and O VI 1032/1037 Å emissivities obtained with data from the Ultraviolet Coronagraph Spectrometer (UVCS) on SOHO. The local emissivities, from heliocentric heights of 1.5 to 3.0 solar radii, were determined from 3-D reconstructions of line-of-sight intensities obtained during the first Whole Sun Month Campaign (10 August to 8 September 1996). The models use electron densities derived from polarized brightness measurements made with the visible light coronagraphs on UVCS and LASCO, supplemented with data from Mark III at NCAR/MLSO. Electron temperature profiles are derived from 'freezing-in' temperatures obtained from an analysis of charge state data from SWICS/Ulysses. The work concentrates on neutral hydrogen outflow velocities which depend on modeling the absolute coronal H I Lyα emissivities. We use an iterative method to determine the neutral hydrogen outflow velocity with consistent values for the electron temperatures derived from a freezing-in model. [ABSTRACT FROM AUTHOR]

In this paper we discuss some characteristics of an equatorial streamer observed by UVCS in July 1997. We determine the height distribution of the Ly-α total intensity and of its width. We focus our attention, in particular, on the time variability of these parameters. [ABSTRACT FROM AUTHOR]

In recent UVCS/SOHO White Light Channel (WLC) observations we found quasi-periodic variations in the polarized brightness (pB) in the polar coronal holes at heliocentric distances of 1.9 to 2.45 solar radii. The motivation for the observation is the 2.5D MHD model of solar wind acceleration by nonlinear waves, that predicts compressive fluctuations in coronal holes. In February 1998 we performed new observations using the UVCS/WLC in the coronal hole and obtained additional data. The new data corroborate our earlier findings with higher statistical significance. The new longer observations show that the power spectrum peaks in the 10–12 minute range. These timescales agree with EIT observations of brightness fluctuations in polar plumes. We performed preliminary LASCO/C2 observations in an effort to further establish the coronal origin of the fluctuations. [ABSTRACT FROM AUTHOR]

The Spartan 201 flights from 1993 to 1995 provided us with observations in H I Lyman-α of several coronal hole/streamer boundaries and adjacent streamers during the declining phase of the current solar cycle: Analysis of the latitudinal dependence of the line intensities clearly shows that there is a boundary region at the coronal hole/streamer interface where the H I Lyman-α intensity reaches a minimum value. Similar results are also found in UVCS/SOHO observations. We also discuss differences in the coronal hole/streamer boundaries for different types of streamers and their changes over the three year period of Spartan 201 observations. [ABSTRACT FROM AUTHOR]

Ultraviolet emission line profiles have been measured on 15-29 September 1997 for H I 1216 Å, O VI 1032, 1037 Å and Mg X 625 Å in a polar coronal hole, at heliographic heights ϱ (in solar radii) between 1.34 and 2.0. Observations of H I 1216 Å and the O VI doublet from January 1997 for ϱ = 1.5 to 3.0 are provided for comparison. Mg X 625 Å is observed to have a narrow component at ϱ = 1.34 which accounts for only a small fraction of the observed spectral radiance, and a broad component that exists at all observed heights. The widths of O VI broad components are only slightly larger than those for H I at ϱ = 1.34, but are significantly larger at ϱ = 1.5 and much larger for ϱ > 1.75. In contrast, the Mg X values are less than those of H I up to 1.75 and then increase rapidly up to at least ϱ = 2.0, but never reach the values of O VI. [ABSTRACT FROM AUTHOR]

We made streamer observations with the Ultraviolet Coronagraph Spectrometer (UVCS) on the Solar and Heliospheric Observatory (SOHO) during the early part of 1998, which was a time of moderate solar activity. We present an empirical study of coronal ion kinetics using the line profiles from these observations. Our first and most striking result is that the mid-latitude (ML) streamers have much narrower O VI 1032 Å line profiles than the solar minimum equatorial (SME) streamers. Our second result is that the line profiles from a small collection of ions in ML streamers do not seem to be consistent with the ions having a single temperature and turbulent velocity. We discuss several interpretations, including line of sight (LOS) effects. This work is supported by the National Aeronautics and Space Administration under grant NAG-3192 to the Smithsonian Astrophysical Observatory. [ABSTRACT FROM AUTHOR]

We compared the H I Lyα polar coronal hole profiles obtained during the three Spartan 201 flights (in 1993, 1994, and 1995) and during the more recent UVCS/SOHO mission. We found that at 2.1 R⊙ there are no significant variations of the line shape over the several years of the descending phase of the solar cycle. However, there may be some evidence for the 1.8 R⊙ profiles being broader towards solar minimum. The profiles at 2.1 R⊙ are different from profiles obtained at 1.8 R⊙; they have clearly narrower cores and wide wings. We fitted the profiles with single and/or multiple Gaussian functions and calculated their typical 1/e half widths. [ABSTRACT FROM AUTHOR]

We analyzed UVCS/SOHO data and compared the H I Lyα (121.6 nm) and O VI (103.2 nm, 103.7 nm) emission in the polar and equatorial coronal holes. We found that the emission lines have similar characteristics in these two types of coronal holes. Both types show evidence for superradially diverging boundaries. The latitudinal distribution of the O VI line ratio may indicate that the equatorial coronal hole has O+5 outflow velocities lower than in the polar coronal holes. [ABSTRACT FROM AUTHOR]

Using empirical velocity distributions derived from UVCS and SUMER ultraviolet spectroscopy, we construct theoretical models of anisotropic ion temperatures in the polar solar corona. The primary energy deposition mechanism we investigate is the dissipation of high frequency (10-10000 Hz) ion-cyclotron resonant Alfvén waves which can heat and accelerate ions differently depending on their charge and mass. We find that it is possible to explain the observed high perpendicular temperatures and strong anisotropies with relatively small amplitudes for the resonant waves. There is suggestive evidence for steepening of the Alfvén wave spectrum between the coronal base and the largest heights observed spectroscopically. Because the ion-cyclotron wave dissipation is rapid, even for minor ions like O5+, the observed extended heating seems to demand a constantly replenished population of waves over several solar radii. This indicates that the waves are generated gradually throughout the wind rather than propagated up from the base of the corona. [ABSTRACT FROM AUTHOR]

We present results from SOHO/UVCS measurements of the density and flow speed of plasma at the Sun and again of the same plasma by Ulysses/SWOOPS in the solar wind. UVCS made measurements at 3.5 and 4.5 solar radii and Ulysses was at 5.1 AU. Data were taken for nearly 2 weeks in May–June 1997 at 9–10 degrees north of the equator in the streamer belt on the east limb. Density and flow speed were compared to see if near Sun characteristics are preserved in the interplanetary medium. By chance, Ulysses was at the very northern edge of the streamer belt. Nevertheless, no evidence was found of fast wind or mixing of slow wind with fast wind coming from the northern polar coronal hole. The morphology of the streamer belt was similar at the beginning and end of the observing period, but was markedly different during the middle of the period. A corresponding change in density (but not flow speed) was noted at Ulysses. [ABSTRACT FROM AUTHOR]

The histamine-induced respiratory reflex response arising from the lung deflation (irritant) receptors was influenced by both procaine and isoprenaline, but in an essentially different manner. Procaine administered via the pulmonary circulation prevented or interrupted the asthmatic tachypnoea associated with stimulation of the lung deflation receptors. The effect was less consistently obtained when the drug was given by way of the bronchial circulation or as an aerosol. It is concluded that the lung deflation receptors in the guinea-pig are located in sites easily accessible by way of the pulmonary circulation, i.e., in the peripheral airways. Isoprenaline, irrespective of the way of administration, counteracted the asthmatic increase in bronchial resistance which underlies the stimulation of the lung deflation receptors. A respiratory response, however, characterized by increased respiratory rate, still occurred when the drug was administered either before or after histamine inhalation. The tachypnoic response to isoprenaline is probably of central origin. [ABSTRACT FROM AUTHOR]

The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) has observed the extended solar corona between 1 and 10 R· for more than two years. We review spectroscopic and polarimetric measurements made in coronal holes, equatorial streamers, and coronal mass ejections, as well as selected non-solar targets. UVCS/SOHO has provided a great amount of empirical information about the physical processes that heat and accelerate the solar wind, and about detailed coronal structure and evolution. [ABSTRACT FROM AUTHOR]

The purpose of the study was to examine the response of vagal pulmonary slowly adapting stretch receptors (SAR) to high-frequency oscillation ventilation (HFO) in rabbits by analyzing the afferent activity recorded in vagal single-fiber preparations. The vagal afferent activity was recorded during short runs of HFO with a stroke volume of 2-3 ml/kg applied at oscillation frequencies (f) of 5, 10, 15, 20, and 25 Hz and each frequency at three levels of mean airway pressure (P), namely, 1, 3, and 8 cm HO. The receptor discharge rates during HFO were compared with those during quiet spontaneous breathing as well as during static lung inflations and deflations. The majority of SAR was stimulated by HFO, however, the SAR discharge patterns during HFO were less homogeneous than during static lung inflations. The heterogeneity of SAR responses to HFO became pronounced with increasing P and f, From the results, we conclude that HFO elicits heterogeneous discharge patterns of SAR, but the previously reported heterogeneity of responses of rapidly adapting receptors was even greater. This heterogeneity of vagal activity is probably the result of heterogeneous mechanical conditions within the lungs during HFO and may, in turn, give rise to the various types of respiratory reflex responses to HFO. [ABSTRACT FROM AUTHOR]

We analysed the respiratory response of anaesthetised rabbits to aerosols or injections of histamine. Shortening of expiratory duration ( t ) could preceed shortening of inspiratory duration ( t ) by a few breaths (continuous acceleration) or t could remain constant until an augmented breath preceded a large reduction in t (discontinuous acceleration). The responses were not appreciably modified by a block of pulmonary stretch receptors and are therefore attributable to increased activity of lung irritant and, to a lesser extent, C-fibre receptors. The results are discussed in relation to the mechanisms controlling t and t . We conclude that such mechanisms are relatively independent under certain circumstances and that irritant receptors may have an indirect role in shortening t . [ABSTRACT FROM AUTHOR]

The purpose of the present study was to investigate the effect of exercise induced hyperventilation and hypocapnia on airway resistance ( Raw), and to try to answer the question whether a reduction of Raw is a mechanism contributing to the increase of endurance time associated with a reduction of exercise induced hyperventilation as for example has been observed after respiratory training. Eight healthy volunteers of both sexes participated in the study. Cycling endurance tests (CET) at 223 (SD 47) W, i.e. at 74 (SD 5)% of the subject's peak exercise intensity, breathing endurance tests and body plethysmograph measurements of pre- and postexercise Raw were carried out before and after a 4-week period of respiratory training. In one of the two CET before the respiratory training CO2 was added to the inspired air to keep its end-tidal concentration at 5.4% to avoid hyperventilatory hypocapnia (CO2-test); the other test was the control. The pre-exercise values of specific expiratory Raw were 8.1 (SD 2.8), 6.8 (SD 2.6) and 8.0 (SD 2.1) cm H2O · s and the postexercise values were 8.5 (SD 2.6), 7.4 (SD 1.9) and 8.0 (SD 2.7) cm H2O · s for control CET, CO2-CET and CET after respiratory training, respectively, all differences between these tests being nonsignificant. The respiratory training significantly increased the respiratory endurance time during breathing of 70% of maximal voluntary ventilation from 5.8 (SD 2.9) min to 26.7 (SD 12.5) min. Mean values of the cycling endurance time ( tcend) were 22.7 (SD 6.5) min in the control, 19.4 (SD 5.4) min in the CO2-test and 18.4 (SD 6.0) min after respiratory training. Mean values of ventilation ( ${\dot V}$E) during the last 3␣min of CET were 123 (SD 35.8) l · min−1 in the control, 133.5 (SD 35.1) l · min−1 in the CO2-test and 130.9 (SD 29.1) l · min−1 after respiratory training. In fact, six subjects ventilated more and cycled for a shorter time, whereas two subjects ventilated less and cycled for a longer time after the respiratory training than in the control CET. In general, the subjects cycled longer the lower the ${\dot V}$E, if all three CET are compared. It is concluded that Raw measured immediately after exercise is independent of exercise-induced hyperventilation and hypocapnia and is probably not involved in limiting tcend, and that tcend at a given exercise intensity is shorter when ${\dot V}$E is higher, no matter whether the higher ${\dot V}$E occurs before or after respiratory training or after CO2 inhalation. [ABSTRACT FROM AUTHOR]

To investigate the role of fluid shifts during the short-term adjustment to acute hypobaric hypoxia (AHH), the changes in lower limb (LV) and forearm volumes (FV) were measured using a strain-gauge plethysmograph technique in ten healthy volunteers exposed to different altitudes (450 m, 2500 m, 3500 m, 4500 m) in a hypobaric chamber. Arterial blood pressure, heart rate, arterial oxygen saturation ( SaO2), endtidal gases, minute ventilation and urine flow were also determined. A control experiment was performed with an analogous protocol under normobaric normoxic conditions. The results showed mean decreases both in LV and FV of −0.52 (SD 0.39) ml · 100 ml−1 and −0.65 (SD 0.32) ml · 100 ml−1, respectively, in the hypoxia experiments [controls: LV −0.28 (SD 0.37), FV −0.41 (SD 0.47) ml · 100 ml−1]. Descent to normoxia resulted in further small but not significant decreases in mean LV [−0.02 (SD 0.11) ml · 100 ml−1], whereas mean FV tended to increase slightly [ + 0.02 (SD 0.14) ml · 100 ml−1]; in the control experiments mean LV and FV decreased continuously during the corresponding times [−0.19 (SD 0.31), −0.18 (SD 0.10) ml · 100 ml−1, respectively]. During the whole AHH, mean urine flow increased significantly from 0.84 (SD 0.41) ml · min−1 to 3.29 (SD 1.43) ml · min−1 in contrast to the control conditions. We concluded that peripheral fluid volume shifts form a part of the hypoxia-induced acute cardiovascular changes at high altitude. In contrast to the often reported formation of peripheral oedema after prolonged exposure to hypobaric hypoxia, the results provided no evidence for the development of peripheral oedema during acute induction to high altitude. However, the marked increase in interindividual variance in SaO2 and urine flow points to the appearance of the first differences in the short-term adjustment even after 2 h of acute hypobaric hypoxia. [ABSTRACT FROM AUTHOR]

During apneic periods elicited by high-frequency oscillatory ventilation (HFOV) a tonic diaphragmatic activity was observed, contrasting with the absence of diaphragmatic activity during apnea induced by lung inflation. To clarify the mechanism underlying the persistence of the diaphragmatic activity during HFOV-induced arrest of breathing the reflex responses to short periods of HFOV, and to periods of lung inflation with airway pressure ( P) equal to the mean P and/or to maximal P during HFOV were examined both before and after the blockade of slowly adapting stretch receptors (SR) by inhalation of sulphur dioxide (SO) in anaesthetized rabbits. In animals with intact SR, the HFOV-induced reflex apnea lasted longer than that induced by lung inflation, the associated diaphragmatic activity being in the most cases higher than the diaphragmatic activity during quiet expiration; inflation, however, completely inhibited diaphragmatic activity. After blockade of SR, spontaneous breathing continued during periods of lung inflation, i.e., the Hering-Breuer inflation reflex was abolished, whereas HFOV still led to a cessation of spontaneous breathing, the associated diaphragmatic activity even exceeding the level observed during quiet inspiration. From these results we conclude that only one part of the reflex response to HFOV is due to SR-stimulation and that in addition other vagal pulmonary receptors (irritant-and/or C-fibre-receptors) are involved. The stimulation of the latter counterbalances the concomitant stimulation of SR, giving rise to the tonic activity of the diaphragm. [ABSTRACT FROM AUTHOR]

In anaesthetized, thoracotomized and artificially ventilated rabbits, the location of pulmonary stretch receptors (SR) was established by means of local mechanical stimulation as well as by micro-injections of the local anaesthetic cinchocaine. Differences in SR activity were analyzed in relation to the receptor site during specific stimulation by lung inflation, as well as during nonspecific activation by ammonia inhalation. Out of 107 SR, 55% were located in larger airways, i.e., in the trachea, main bronchus and lobar bronchi ('central SR'), whereas 45% were found to lie more peripherally ('peripheral SR'). There were several differences with respect to the discharge pattern evoked by lung inflation and by ammonia inhalation between SR of different locations. The increase of discharge rate evoked by lung inflation and by ammonia inhalation was significantly greater in peripheral than in central SR. Significantly more central than peripheral SR discharged throughout the whole respiratory cycle, i.e., even at end-expiratory lung volume. Furthermore, a delayed inspiratory recruitment as well as a transient cessation of firing after the initial increase of activity, which followed ammonia inhalation, occurred more frequently in central than in peripheral SR. [ABSTRACT FROM AUTHOR]

In anaesthetized rabbits the effects of high frequency ventilation (HFV) on breathing pattern and on stretch receptor (SR) activity were examined in order to elucidate the mechanism underlying the inhibition of respiration during HFV. An attempt was undertaken to compare the effects of HFV with those of static lung inflations. HFV applied in frequencies between 5 Hz and 25 Hz and with peak airway pressure (Paw) between 5 and 15 cm HO led - proportionally to Paw - to a gradual prolongation of expiration up to an apnoea. Similar effects occurred during lung inflations, although at higher Paw than during HFV. HFV-induced apnoea was accompanied by a tonic phrenic and diaphragmatic activity which was absent during inflation-induced apnoea. In addition to the activity due to spontaneous breathing, during HFV the SR discharge rate increased with each positive airflow pulse particularly in the expiratory phase, whereas the inspiratory discharge rate was less affected. During static lung inflations there was a parallel increase of both inspiratory and expiratory SR activity, the expiratory discharge rate, however, remaining lower and the inspiratory discharge rate rising more than during HFV. It is concluded that the HFV-induced increase of expiratory SR discharge rate may account for the inhibition of spontaneous breathing during HFV. The persistence of phrenic and diaphragmatic activity during HFV-induced apnoea is thought to be due to activation of irritant receptors. [ABSTRACT FROM AUTHOR]

The contribution of pulmonary stretch receptor (SR) activity to the changes in breathing pattern ( f, V, t, t, t: t) following inhalation of ammonia vapour has been studied in rabbits at three levels of lung distension, i.e., three levels of SR activity, and during reversible SO-blockade of SR. The results show that the increase in breathing frequency ( f) and the decrease in tidal volume ( V) due to ammonia inhalation are almost identical for animals with and without blockade of SR, whereas the duration of inspiration and expiration ( t, t) as well as their relationship ( t: t) vary considerably, the variations dependeing on the level of SR activity. For a given t the expiration was longer in animals with SR intact than in animals with SR blocked. It is concluded that in rabbits the increased activity of SR after inhalation of ammonia counteracts significantly the predominant effects of irritant (deflation) receptor stimulation, thus rendering possible a longer expiration. [ABSTRACT FROM AUTHOR]

The activity in single vagal fibres arising from lung stretch receptors was recorded in rabbits during normal breathing at rest and during tachypnoea caused by inhalation of histamine or ammonia. The rate of argon elimination from the lungs was analysed to estimate the accompanying changes of lung ventilation. The results show that the majority of stretch receptors increased their activity during irritant-induced tachypnoea, the discharge frequency being always higher during inspiration than during expiration. Only a few fibres did not change or decreased their activity. The comparison of the results with previous findings in guinea-pig revealed that the discharge pattern of stretch receptors following inhalation of irritants was different in these two species, whereas the respiratory reactions and the unevenness of ventilation were comparable. It is suggested that the differences in the discharge pattern of stretch receptor fibres during irritant-induced hyperpnoea in rabbit and guinea-pig are due to differences in the location of the stretch receptors concerned. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Neurology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The correlation between pulmonary stretch receptor activity and inspiration-expiration duration quotient, as well as respiratory frequency (Hering-Breuer relfexes) has been established before and during an asthma attack in the guinea-pig The Hering-Breuer reflexes subserving the self-regulation of breathing during uninfluenced spontaneous breathing no longer prevail after induction of a bronchial asthma attack. Increased stretch receptor activity following increased lung volume does not lead to inhibition of inspiratory activity (lung inflation reflex), but to an enhancement of the asthmatic tachypnoea. The latter is assumed to result from the expiratory self-compression of the lungs (lung deflation reflex). The enhancement of the deflation reflex by increasing lung volume during the asthma attack is discussed with regard to the unerven ventilation and the conditions in lung mechanics underlying the excitation of the lung deflation or collapse endings. [ABSTRACT FROM AUTHOR]

Spartan 201 is a shuttle deployed spacecraft that is scheduled to perform ultraviolet spectroscopy and white light polarimetry of the extended solar corona during two 40 hour missions to occur in September 1994 and August 1995. The spectroscopy is done with an ultraviolet coronal spectrometer which measures the intensity and spectral line profile of HI Lyα up to heliocentric heights of 3.5 solar radii. It also measures the intensities of the OVI doublet at 1032 and 1037 Å and of Fe XII at 1242 Å. The HI Lyα line profile measurements are used to determine the random velocity distribution of coronal protons along the line-of-sight. The absolute HI Lyα intensities can be used together with electron densities from the white light coronagraph to estimate electron temperatures from hydrogen ionization balance calculations, and bulk outflow velocities from models of Doppler dimmed resonant scattering. Intensities of minor ion lines are used to determine coronal abundances and outflow velocities of O. Ultraviolet spectroscopy of extended coronal regions from the 11 April 1993 mission of Spartan 201 are discussed. [ABSTRACT FROM AUTHOR]

The Ultraviolet Coronal Spectrometer on Spartan 201 obtained measurements of HI Ly α line profiles and O VI λ103.2/103.7 nm integrated intensities in a helmet streamer. Similar measurements were made on the solar disk to characterize the incident radiation which is the source for the resonantly scattered component of the lines. A description of the H I Ly α observations in the streamer will be presented. A more complete physical description of the observed coronal regions will become available after the analysis of additional data from coordinated observations made by visible coronagraphs and x-ray telescopes. [ABSTRACT FROM AUTHOR]

The instruments on the Spartan 201 spacecraft are an Ultraviolet Coronal Spectrometer and a White Light Coronagraph. Spartan 201 was deployed by the Space Shuttle on 11 April 1993 and observed the extended solar corona for about 40 hours. The Ultraviolet Coronal Spectrometer measured the intensity and spectral line profile of HI Lyα and the intensities of OVI 103.2 and 103.7 nm. Observations were made at heliocentric heights between 1.39 and 3.5 R. Four coronal targets were observed, a helmet streamer at heliographic position angle 135°, the north and south polar coronal holes, and an active region above the west limb. Measurements of the HI Lyα geocorona and the solar irradiance were also made. The instrument performed as expected. Straylight suppression, spectral focus, radiometric sensitivity and background levels all appear to be satisfactory. The uv observations are aimed at determining proton temperatures and outflow velocities of hydrogen, protons and oxygen ions. Preliminary results from the north polar coronal hole observations are discussed. [ABSTRACT FROM AUTHOR]

The Harvard-Smithsonian Center for Astrophysics and the High Altitude Observatory have defined a joint coronagraphs experiment for a future Spacelab mission. The instrumentation package would include an ultraviolet light coronagraph to measure the intensity and profiles of spectral lines formed between 1.2 and 8 solar radii from Sun center and a white light coronagraph to measure the intensity and polarization of visible light. The overall goals of the joint program are to use new coronal plasma diagnostic techniques to understand the physical processes and mechanisms operating in the solar corona, to understand the acceleration of high-speed and low-speed solar wind streams and to extrapolate this knowledge to other stars in order to help understand the physics of stellar coronae and stellar mass loss. [ABSTRACT FROM AUTHOR]

The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) is being used to observe the extended solar corona from 1.25 to 10 R⊙ from Sun center. Initial observations of polar coronal holes and equatorial streamers are described. The observations include measurements of spectral line profiles for HI Lα and Lβ, Ovi 1032 Å and 1037 Å, Mgx 625 Å, Fexii 1242 Å and several others. Intensities for Mgx 610 Å, Sixii 499 Å, and 520 Å, Sx 1196 Å, and 22 others have been observed. Preliminary results for derived H0, O5+, Mg9+, and Fe11+ velocity distributions and initial indications of outflow velocities for O5+ are described. In streamers, the H0 velocity distribution along the line of sight (specified by the value at e-1, along the line of sight) decreases from a maximum value of about 180 km s-1 at 2 R⊙ to about 140 km s-1 at 8 R⊙. The value for O5+ increases with height reaching a value of 150 km s-1 at 4.7 R⊙. In polar coronal holes, the O5+ velocity at e-1 is about equal to that of H0 at 1.7 R⊙ and significantly larger at 2.1 R⊙. The O5+ in both streamers and coronal holes were found to have anisotropic velocity distributions with the smaller values in the radial direction. [ABSTRACT FROM AUTHOR]

The Ultraviolet Coronagraph Spectrometer on the SOHO satellite covers the 940–1350 Å range as well as the 470–630 Å range in second order. It has detected coronal emission lines of H, N, O, Mg, Al, Si, S, Ar, Ca, Fe, and Ni, particularly in coronal streamers. Resonance scattering of emission lines from the solar disk dominates the intensities of a few lines, but electron collisional excitation produces most of the lines observed. Resonance, intercombination and forbidden lines are seen, and their relative line intensities are diagnostics for the ionization state and elemental abundances of the coronal gas. The elemental composition of the solar corona and solar wind vary, with the abundance of each element related to the ionization potential of its neutral atom (First Ionization Potential–FIP). It is often difficult to obtain absolute abundances, rather than abundances relative to O or Si. In this paper, we study the ionization state of the gas in two coronal streamers, and we determine the absolute abundances of oxygen and other elements in the streamers. The ionization state is close to that of a log T = 6.2 plasma. The abundances vary among, and even within, streamers. The helium abundance is lower than photospheric, and the FIP effect is present. In the core of a quiescent equatorial streamer, oxygen and other high-FIP elements are depleted by an order of magnitude compared with photospheric abundances, while they are depleted by only a factor of 3 along the edges of the streamer. The abundances along the edges of the streamer (‘legs’) resemble elemental abundances measured in the slow solar wind, supporting the identification of streamers as the source of that wind component. [ABSTRACT FROM AUTHOR]

The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) is composed of three reflecting telescopes with external and internal occultation and a spectrometer assembly consisting of two toric grating spectrometers and a visible light polarimeter. The purpose of the UVCS instrument is to provide a body of data that can be used to address a broad range of scientific questions regarding the nature of the solar corona and the generation of the solar wind. The primary scientific goals are the following: to locate and characterize the coronal source regions of the solar wind, to identify and understand the dominant physical processes that accelerate the solar wind, to understand how the coronal plasma is heated in solar wind acceleration regions, and to increase the knowledge of coronal phenomena that control the physical properties of the solar wind as determined by in situ measurements. To progress toward these goals, the UVCS will perform ultraviolet spectroscopy and visible polarimetry to be combined with plasma diagnostic analysis techniques to provide detailed empirical descriptions of the extended solar corona from the coronal base to a heliocentric height of 12 solar radii. [ABSTRACT FROM AUTHOR]