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Photometric observations of Uranus and Neptune made each year since 1972 at Lowell Observatory in the b (472 nm) and y (551 nm) filters of the Stromgren photometric system recorded the mainly seasonal variations of disk-integrated albedos of these objects. The measurements predate Voyager and Hubble Telescope multi-wavelength imaging and overlap more than a decade of ground-based adaptive optics near-IR imaging. This paper is a final archive and brief summarizing discussion of observations through 2016 and includes electronic tables of 360 observations of Uranus and 433 observations of Neptune.

Sao Paulo State Univ UNESP, Ctr Human Reprod Prof Franco Jr, Paulista Ctr Diag Res & Training, Dept Gynecol & Obstet,Botucatu Med Sch, Ribeirao Preto, Brazil

Context. A recent paper by Shapiro and colleagues (2011, A&A, 529, A67) reconstructs spectral and total irradiance variations of the Sun during the holocene. Aims. In this note, we comment on why their methodology leads to large (0.5%) variations in the solar TSI on century-long time scales, in stark contrast to other reconstructions which have ≲ 0.1% variations.Methods. We examine the amplitude of the irradiance variations from the point of view of both solar and stellar data.Results. Shapiro et al.’s large amplitudes arise from differences between the irradiances computed from models A and C of Fontenla and colleagues, and from their explicit assumption that the radiances of the quiet Sun vary with the cosmic ray modulation potential. We suggest that the upper photosphere, as given by model A, is too cool, and discuss relative contributions of local vs. global dynamos to the magnetism and irradiance of the quiet Sun. We compare the slow (>22 yr) components of the irradiance reconstructions with secular changes in stellar photometric data that span 20 years or less, and find that the Sun, if varying with such large amplitudes, would still lie within the distribution of stellar photometric variations measured over a 10−20 year period. However, the stellar time series are individually too short to see if the reconstructed variations will remain consistent with stellar variations when observed for several decades more.Conclusions. By adopting model A, Shapiro et al. have over-estimated quiet-Sun irradiance variations by about a factor of two, based upon a re-analysis of sub-mm data from the James Clerk Maxwell telescope. But both estimates are within bounds set by current stellar data. It is therefore vital to continue accurate photometry of solar-like stars for at least another decade, to reveal secular and cyclic variations on multi-decadal time scales of direct interest to the Sun.

Background Context-sensitive times to 50%, 80%, and 90% elimination from the brain have been calculated for volatile anaesthetics. This does not represent complete recovery because there are important residual effects even at 90% elimination, and the effect of anaesthetic metabolism on the rate of elimination has not been considered. Methods A physiologically based model of anaesthetic uptake and distribution was elaborated to include anaesthetic metabolism and fluoride kinetics. It was validated by comparing its predictions with real data, then experiments were undertaken to calculate the partial pressure of anaesthetic in the brain after the administration of 1 MAC of halothane, enflurane, isoflurane, sevoflurane or desflurane, or 50% of inspired nitrous oxide or xenon, for up to 6 h. Results The model generated data that were compatible with many published measurements of anaesthetic kinetics and fluoride production. Metabolism had a negligible effect on kinetics. After 4 h of anaesthesia, the model predicted body content to be 28 g nitrous oxide, 26 g desflurane, 14 g sevoflurane, or 15 g isoflurane, and 99.9% brain elimination times were then 9 h for nitrous oxide, 33 h for desflurane, 52 h for sevoflurane, and 71 h for isoflurane. At this stage of elimination, the whole body still retained between 4% and 13% of the absorbed dose. Differences between sevoflurane and desflurane were obvious only during the final stages of elimination (>99% from the vessel-rich group). Conclusions Large amounts of anaesthetics are absorbed during anaesthesia and significant amounts remain in the body for days after apparent recovery.

We present 14 years of contemporaneous photometric and spectroscopic observations of 28 solar analog stars, taken with the Tennessee State University Automatic Photometric Telescopes at Fairborn Observatory and the Solar-Stellar Spectrograph at Lowell Observatory. These are the best observed and most nearly Sun-like of the targets in our magnitude-limited (V ≤ 7.5) sample. The correlations between luminosity and activity reveal the expected inverse activity-brightness correlations for active stars. Strong direct correlations between activity and brightness are not prevalent for the less active solar age stars, but are precision limited. The Sun does not appear to have unusually low photometric variability when compared with the most Sun-like inactive solar analogs. We present evidence that the activity index R'HK is not a good discriminant of Maunder Minimum candidate stars. On the basis of a star that appears to have transitioned from a low-variability state to a cycling state, we investigate the regime in which stars might switch from faculae-dominated to spot-dominated variations.

Measurements at Lowell Observatory of Titan in the b (472 nm) and y (551 nm) filters of the Stromgren photometric system at thirty four consecutive apparitions (282 nights) from 1971/72 to 2006 show a 10% sinusoidal variation that lags seasonal extremes by about 1/8 of a Titan year. The seasonal variations are asymmetric: the autumn lightcurve maxima of the northern and southern hemispheres differ significantly as do the spring lightcurve minima. Changes also occur from one Titan year to the next: Titan was ∼3% fainter in b and ∼1% fainter in y following the 2002 southern summer solstice than it was one Titan year earlier in 1973. These changes appear to be intrinsic to Titan's atmosphere and cannot be explained by instrumental effects and changing geometries. Orbital variations visible in recent Hubble Space Telescope images at 673 nm and Voyager orange images (590–640 nm) may have a small ( 0.002 ± 0.001 mag ) counterpart in the b, y photometric record (eastern elongation brighter, consistent with the Cassini near-infrared albedo map).

We develop an estimate of the complete outdoor lighting of Flagstaff Arizona, as well as lighting- use densities (lumens per acre) for a number of different land uses. We find a total outdoor light output of 173 million lumens (Mlm) including sports lighting, and 139 Mlm without sports lighting, with an uncertainty of about 7%. The average fraction escaping directly upward from light fixtures is estimated to be 8.3%. After correcting approximately for near-ground blocking described in the accompanying paper by Luginbuhl et al., total uplight is estimated at 17.9 Mlm or 12.2 Mlm with and without sports lighting, respectively. Of these 17.9 Mlm, 33% arise from sports lighting, when it is on; when sports lighting is off, commercial and industrial lighting account for 62% with the remainder dominated by residential (14%) and roadway lighting (12%). We show that the 1989 Flagstaff lighting code that limited total outdoor lighting on new construction has reduced the growth rate of lighting, re- sulting in a 17% growth in light escaping into the sky from 1989 to 2003, compared to a 43% increase expected if the 1989 code had not been enacted. If all legally nonconforming lighting installed before 1989 were to be brought into compliance with the code, we would expect sky glow in Flagstaff to actually decrease by 36% compared to that in 2003; if all lighting, including residential, could be converted to fully shielded fixtures, sky glow would decrease to about half the current value. The implications for the most effective ways to address sky glow through lighting codes are discussed.

We present panoramic sky brightness measures in the Johnson V band made at the US Naval Observatory Flagstaff Station. We find that these measures show much less sky glow from Flagstaff than expected using the total light output and unshielded fraction determined recently by Luginbuhl et al. and Garstang's 1991 modeling approach. We suggest the difference arises principally from the diminution of upward-directed light after emission from light fixtures and reflection from the ground due to interaction with structures and vegetation. This interaction not only reduces the effective albedo, it also disproportionately reduces flux emitted upward at angles near the horizontal. We explore the size and consequences of this factor in light pollution modeling, and propose a modified upward angular distribution function to account for this effect.

We examine patterns of variation of 32 primarily main sequence stars, extending our previous 7-12 year time series to 13-20 years by combining b, y data from Lowell Observatory with similar data from Fairborn Observatory. Parallel chromospheric Ca II H and K emission data from the Mount Wilson Observatory span the entire interval. The extended data strengthen the relationship between chromospheric and photometric variation derived previously. Twenty-seven stars are deemed variable. On a year-to-year timescale young active stars become fainter when their Ca II emission increases while older less active stars such as the Sun become brighter when their Ca II emission increases. The Sun's total irradiance variation, scaled to the b and y filter photometry, still appears to be somewhat smaller than stars in our limited sample with similar mean chromospheric activity, but we now regard this discrepancy as probably due mainly to our limited stellar sample

A modified patient-controlled analgesia pump provided doses of propofol 3 mg or midazolam 0.1 mg in 0.3 ml, over 5.4 s, with no lockout, during transvaginal oocyte retrieval. Alfentanil 0.2 mg was administered at three points during the procedure, and on request. Patients were randomly assigned to receive either propofol (25 patients) or midazolam (22 patients). The mean age, weight, duration of procedure and dose of alfentanil were similar in both groups. Onset of sedation with propofol or midazolam took 70.6 (SD 22.4) and 106.3 (50.7) s respectively. Mean doses over the first 5 min were midazolam 2.7 (1.2) mg, and propofol 54 (18) mg. Thereafter requirements decreased: midazolam 0.065 (0.065) mg.min-1, propofol 2.1 (1.3) mg.min-1. All patients successfully completed the procedure; none required additional sedation. P-deletion, reaction time, and critical flicker fusion tests revealed similar depression in both groups immediately postoperatively. After 30 min the p-deletion and critical flicker fusion scores were still impaired in the midazolam, but not in the propofol, group.

Synoptic measurements of activity in Sun-like stars have been performed continuously since 1966, and the largest set comes from the Mount Wilson HK project, in the form of the well-known S index. We have been monitoring the activity and variability of the Sun and a large sample of Sun-like stars, in terms of S and absolute flux, since 1994 with the Solar-Stellar Spectrograph (SSS) at Lowell Observatory. Directly inspired by the similar long-term program at Mount Wilson Observatory, the SSS incorporates both an HK spectrograph and an echelle for visible and far-red observations. This is the first of three papers presenting the results of some 20,000 observations of the Sun and Sun-like stars with the SSS. In this paper we describe our program, review the calibration of solar and stellar fluxes to S and the chromospheric emission fraction R'HK, compare our derived stellar activity measures to those from other programs, and discuss the broad characteristics of the activity and variability in our target set, with particular attention to good solar analogs and noncycling stars. In subsequent papers we will discuss the echelle data and present detailed examinations of stars of particular interest.

Long-term photometric measurements of Uranus and Neptune through 2005 show variations in brightness. For Uranus, much of the variation can be interpreted as seasonal, i.e., caused by viewing angle changes of an oblate planet. The photometry suggests that if seasonal variations on Uranus are north–south symmetric, then the northern pole should begin to brighten in 2006. However, seasonal “aspect” changes cannot explain all the variation; the Uranus observations require intrinsic atmospheric change. Furthermore, Uranus observations spanning many scale heights in the atmosphere may show similar change. For Neptune, variations in sub-solar latitude may explain the general shape of the long-term light curve, but significant deviations occur that have no explanation at present. Observations are needed over a longer temporal baseline than currently exists to fully characterize both atmospheres.

Aim To describe how the stability of oxygen saturation measured by pulse oximetry (SpO2%) varies within and between infants with bronchopulmonary dysplasia (BPD). Methods Clinically stable infants with BPD had SpO2 measured at different inspired oxygen concentrations (FIO2 expressed as %). A computer model of gas exchange, that is, ventilation/perfusion ratio (VA/Q) and shunt, plotted the curve of SpO2 versus FIO2 best fitting these data. The slope of this curve is the change in SpO2 per % change in FIO2, hence SpO2 stability, calculated at each SpO2 from 85% to 95%. Results Data from 16 infants with BPD previously described were analysed. The dominant gas exchange impairment was low VA/Q (median 0.35, IQR, 0.16–0.4, normal 0.86). Median shunt was 1% (IQR, 0–10.5; normal

Photoelectric intermediate-band b and y photometry of Uranus and Neptune obtained at each apparition since 1972, combined with broadband B and V photometry from 1950 to 1966, provide a record of planetary variability covering 2/3 of Uranus' 84-year orbital period and 1/3 of Neptune's 165-year orbital period. Almost all of the data were obtained with a dedicated 21-inch photometric telescope at Lowell Observatory. The data are quite homogeneous, with yearly uncertainties typically smaller than 0.01 mag (1%). The lightcurve of Uranus is sinusoidal with peaks at the solstices. The b amplitude slightly exceeds the expected 0.025 mag purely geometrical variation caused by oblateness as the planetary aspect changes, seen from Earth. The y amplitude is several times larger, indicating a strong equator-to-pole albedo gradient. The lightcurve is asymmetrical with respect to southern solstice, evidence of a temporal albedo variation. Neptune's post-1972 lightcurve exhibits a generally rising trend since 1972 interpreted by Sromovsky et al. [Sromovsky, L.A., Fry, P.M., Limaye, S.S., Baines, K.H., 2003. Icarus 163, 256–261] as a lagged sinusoidal seasonal variation. However, the 1950–1966 lightcurve segments are much fainter than expected, missing the proposed seasonal sinusoid by 0.1–0.2 mag. A major unknown component is therefore needed to explain Neptune's long-term variation. The apparent relationship between Neptune's brightness variation and the 11-year solar cycle seen in cycles 21–22 (1972–1996) has apparently now faded away. Further interpretation of the data in this paper will be found in a companion paper by Hammel and Lockwood [Hammel, H.B., Lockwood, G.W., 2005. Icarus. Submitted for publication].

Imaging of Uranus in 2003 with the Keck 10-m telescope reveals banded zonal structure and dozens of discrete cloud features at J and H bands; several features in the northern hemisphere are also detectable at K′. By tracking features over four days, we extend the zonal wind profile well into the northern hemisphere. We report the first measurements of wind velocities at latitudes − 13 ° , + 19 ° , and northward of + 43 ° , the first direct wind measurements near the equator, and the highest wind velocity seen yet on Uranus ( + 218 m / s ). At northern mid-latitudes ( + 20 ° to + 40 ° ), the winds appear to have accelerated when compared to earlier HST and Keck observations; southern wind speeds ( − 20 ° to − 43 ° ) have not changed since Voyager measurements in 1986. The equator of Uranus exhibits a subtle wave structure, indicated by diffuse patches roughly every 30° in longitude. The largest discrete cloud features on Uranus show complex structure extending over tens of degrees, reminiscent of activity seen around Neptune's Great Dark Spot during the Voyager encounter with that planet. There is no sign of a northern “polar collar” as is seen in the south, but a number of discrete features seen at the “expected” latitudes may signal the early stages of development of a northern collar.

We present an analysis of more than 3700 observations of the Ca II H and K lines in 57 Sun-like stars and over 3000 analogous observations of the Sun. Ten of the 57 stars under consideration are observed in flat states, but these stars do not always exhibit overall Ca II H and K core brightness below that of solar minimum. Solar activity minimum lies near the lowest level observed for stars with cyclic or irregular variability, but many flat stars have HK activity levels comparable to or exceeding that of solar minimum. While flat activity stars may be in periods of extended activity minima analogous to the solar Maunder minimum, a significant reduction in magnetic activity during such periods is not implied (although it is also not rejected) by the data.

The authors have successfully combined photometric observations of about 30 sun-like stars from Mount Wilson, Lowell, and Fairborn Observatories to extend their joint time series from 12 to 17 years. The stability of the statistical relationships between chromospheric and brightness variability, derived previously, suggests that the full range of variation on the decadal time-scale has probably now been observed for most of their program stars. Young, active stars become fainter as their chromospheric Ca II HK emission increases, while older, less active stars, such as the Sun, become brighter as their HK emission increases. The Sun's photometric variation still appears to be somewhat small in amplitude at present, compared to other stars in this sample with similar mean chromospheric activity.

During the last week of June 2001, a bright apparition of Neptune's South Polar Feature (SPF) at 70°S was observed to develop and decay in less than 30 hours, displaying contrast of ∼2.5 at 619 nm. Assuming that the same SPF was observed on two consecutive rotations of Neptune, the feature moved eastward at 3.2±1.8° hr−1 (130±80 m s−1). The SPF made no obvious appearances during eight other Hubble Space Telescope (HST) observations of Neptune between July 2000 and June 2001, although there was a faint feature at 70°S in one image in October 2000. A prominent SPF was present in near-IR Keck Telescope images in August 2000. Bright SPFs are seen on ∼10% of the HST images of Neptune obtained since 1994, and a fainter SPF is visible on another ∼10%. An SPF bright enough to be visible at HST resolution was present around half the time during the last week of Voyager's approach to Neptune in August 1989, with one prominent brightening, suggesting that the SPF is less visible now than in 1989.

We present Stromgren b (472-nm) and y (551-nm) photometry of Neptune based on photoelectric measurements obtained at every apparition from 1972 to 2000. Neptune has brightened by 11% in b and 10% in y since 1980 with most of the increase occurring after 1990. By appending b data to published B magnitudes measured at Lowell from 1950 to 1966 and transformed to b , we show that Neptune is now brighter than at any time during the past half century. The nature of the year-to-year variations changed around 1990 when a steady rising trend overshadowed what appeared to be an inverse correlation with cyclic solar activity. By matching observations in b and y with near-infrared J (1.2-μm) and K (2.2-μm) photometry before, during, and after Neptune's 1976 infrared outburst, we show that the pattern of visible albedo variation parallels the infrared variation but with an amplitude 20–50 times smaller. A detailed comparison of photometry with ground-based and Voyager images at visible and red wavelengths during the 1989 Voyager encounter shows that small brightness variations occur when large discrete features rotate across Neptune's disk. This provides a rough association between visible features and photometric effects that we use to infer the state of Neptune's atmosphere for years when only photometry was available. A year-by-year analysis of variance of the photometry suggests that the 1976 and 1986–1989 infrared outbursts were isolated episodes of unusually vigorous atmospheric activity. Detrended magnitudes of Neptune are correlated with solar activity over the entire 29-year interval as well as 22-year subintervals, with solar UV now being favored as a causative mechanism rather than solar modulated galactic cosmic rays.

Hubble Space Telescope imaging of Uranus in 1994, 1997, 1998, and 2000 revealed 13 cloud features, allowing the first measurements of wind velocities at northern latitudes not accessible to the Voyager cameras and new measurements of southern-latitude wind velocities determined during the 1986 Voyager encounter. Images acquired with the Keck 10-meter telescope adaptive optics system in June 2000 also showed some of the same features. Wind speeds inferred from feature motions—along with additional measurements by Karkoschka (1998, Science 280 ) and Voyager measurements (Smith et al . 1986, Science 246 )—indicate a zonal wind profile that is asymmetric with respect to the equator. Small but consistent differences are seen between the newer data and a profile determined from Voyager data: nearly all the newer measurements have slightly slower velocities than expected. We cannot yet determine whether the source of these differences is a slowly changing Uranian wind profile or subtle latitudinal structure in a temporally constant profile. If Uranus' winds vary with time, this may indicate unusual atmospheric dynamics created by the 98° tilt of the planet's rotation axis.

Activity in solar-like stars is often characterized by one, or at most a handful, of proxy spectral indicators such as Ca II H and K or Hα. In this paper we define and explore composite spectral indices (CSIs), which are derived from consideration of the simultaneous behavior of larger sets of related spectral lines. With judiciously defined CSIs, we can examine the short- and long-term variability in a set of solar or stellar spectra in a complementary way to the traditional K index. In this paper we demonstrate this method, using our solar data series spanning the cycle 22/23 minimum and the initial rise of cycle 23, from 1994 through 1999, and using initial CSIs chosen to be sensitive to the presence of sunspots. We find that despite the relative inactivity of the Sun during the time period in question, analysis of the CSIs reveals the change in sunspot number through solar minimum in a well-defined way. Manifestation of this solar property in the CSIs indicates their utility for study of other physical characteristics in the same way, as well as for comparison of the Sun's physical properties and low-level variability to individual solar analogs.

Forty-eight gynaecological patients were randomly allocated to three groups (target end-tidal sevoflurane concentration 1.2, 1.5 or 2%), and into subgroups for positive or neutral suggestion. Anaesthesia was induced by inhalation of sevoflurane in oxygen. When the target concentration was achieved, the bispectral index, computed from a bi-frontal electroencephalogram, was noted. One of two eight-word lists was then played to prime implicit memory, followed by a positive or neutral suggestion. After surgery, each patient tried to identify 24 words obscured by background noise. Priming increased the likelihood of identifying words in the 1.2% group only, i.e. there was evidence of implicit memory in this group. There was no evidence of a therapeutic effect of positive suggestion (p = 0.3), but the power of this part of the study was low. The bispectral index did not achieve statistical significance as an indicator of susceptibility to priming.

Recent observations with the Wide-Field Planetary Camera (WFPC-2) on the Hubble Space Telescope (HST) show an unexpectedly rapid change in the atmospheric albedo contrast between the north and south hemispheres. In 1994 at blue wavelengths, the north was around 15% brighter than the south, and was expected to fall to about 12% in 1997, but has dropped to only 6% brighter. At some other wavelengths, the contrast has reversed, which was not expected until 2002. The interhemispheric contrast has a time dependence that varies with wavelength; contrast changes in blue lag behind changes in violet and yellow/red. The rapid change and the phase variation with wavelength are consistent with ground-based photometry. A physical model of the transport of high-altitude dark haze by meridional winds is a better description of Titan's behavior than the simple sinusoidal models used to date. Investigation with a radiative transfer model indicates that haze number density changes above 160-km altitude are compatible with the observed hemispheric albedo difference, and require particles >0.1 μm in radius.

The inspired partial pressure of an anaesthetic is often used as an index of arterial partial pressure in small animal experiments. We have investigated the influence of anaesthetic solubility on the ratio of arterial to inspired partial pressure in 24 rats, allocated randomly to receive halothane, isoflurane or desflurane at four different inspired concentrations. The arterial partial pressure of the volatile agent was measured by two-stage headspace analysis using a gas chromatograph calibrated with the same gas used to calibrate the Datex Capnomac that measured the inspired concentration. Mean values of arterial to inspired ratio at the lowest concentrations were 0.60 (95% confidence intervals 0.50, 0.71) for 0.8% halothane, 0.54 (0.38, 0.69) for 0.8% isoflurane, 0.72 (0.59, 0.86) for 1.5% sevoflurane and 0.71 (0.54, 0.87) for 4% desflurane. Analysis of variance showed a significant effect of anaesthetic agent (P = 0.008) on the arterial to inspired ratio. Thus volatile anaesthetic agents do not demonstrate a fixed arterial to inspired ratio in rats.

Currently, the use of classical bioequivalence criteria is being called into question for certain classes of drugs such as bisphosphonates. These compounds typically possess a wide therapeutic index but may be characterized by low and variable absorption. The purpose of this communication was to characterize the highly variable bioavailability of tiludronate using a population pharmacokinetic method (NONMEM program) and compare the results to a standard 2 way cross-over bioequivalence trial in healthy subjects. Over 3500 plasma samples from 153 healthy subjects, representing 12 different clinical trials were pooled for mixed effect modeling purposes (complete data set). These studies, conducted under single and multiple dose conditions, contained all the directly comparable data available in healthy subjects administered a 400 mg dose of tiludronate. A two compartment model with first order absorption was fit to the plasma concentration-time data and a term for relative bioavailability (BA) was included. Intersubject and residual variability were modeled using a constant coefficient of variation (CCV) model. A pilot model development data set was obtained from a 24 subject cross-over bioequivalence study. Population estimates of BA and its associated 90% confidence interval of 1.12 and 0.89-1.35 compared favorably to standard bioequivalence methodology (1.15 and 0.93-1.42, respectively). Since a good fit of predicted and observed plasma concentrations as well as estimates of BA were obtained, a two compartment model with a term for BA was then applied to the complete data set. Under these conditions, BA and its 90% confidence interval were found to be 1.17 and 0.98-1.36. Intersubject variability of 31%, compared with 38% in the pilot model development data set and residual variability of 38% were seen. No differences in absorption characteristics as measured by Ka were found. Good agreement between the population pharmacokinetic parameters were observed when the pilot data set was compared with the full data set. The proposed model was confirmed by creating 10 additional smaller data sets that were matched for the number of subjects given both formulations under single and multiple dose conditions. No change in the estimate of BA was observed under these study conditions. This study demonstrated that population pharmacokinetic methodology can be applied successfully to problematical bioequivalence issues that may occur during the development process. Increasing the number of subjects in the overall analysis did not alter the estimate of BA or its 90% confidence interval, when compared to the original cross-over bioequivalence study. Bayesian approaches can be of value in large clinical trials where typically relatively few plasma samples are obtained from individual subjects.

We presentb(472 nm) andy(551 nm) lightcurves for Uranus based on photoelectric photometry obtained at every apparition from 1972 to 1996. The two branches of the lightcurve before and after the 1985 solstice are offset by ∼0.01 mag inband ∼0.02 mag iny, indicating that the disk-integrated albedo of Uranus increased slightly after solstice. The solar phase coefficients of Uranus also increased at about the same time. Theblightcurve is consistent with the 1986 Voyager 2 BL (477 nm)I/Flatitudinal scans. Theylightcurve differs significantly from the GR (572 nm) scan, suggesting that the polar region may have brightened somewhat over the past 25 years.

We present the results of 10 yr of complementary spectroscopic and photometric observations of the solar twin 18 Scorpii. We show that over the course of its ~7 year chromospheric activity cycle, 18 Sco's brightness varies in the same manner as the Sun's and with a likely brightness variation of 0.09%, similar to the 0.1% decadal variation in the total solar irradiance.

The rate of uptake of sevoflurane during clinical anaesthesia (1.3 MAC) was measured by computer-controlled injection of liquid anaesthetic into a closed breathing system, The cumulative uptake of sevoflurane was 4.8 ml, 7.4 ml. 9.5 ml and 11.5 ml at 30, 60, 90 and 120 min, respectively. The ratio of inspired to end-expired sevoflurane was greater than similar measurements we have made for desflurane in the past, but the absolute rate of sevoflurane uptake was less than the rate of uptake of desflurane in these cases. The rate of uptake was equivalent to 0.59e -0.32t +0.039e -0.036t +0. 105e -0.0034t ml.min -1 liquid sevoflurane. Plasma urea and creatinine measured on the first postoperative day were not significantly different from pre-operative values.

We examine the patterns of variation among a sample of 35 stars that includes the Sun, particularly on the timescale of the 11 yr solar activity cycle. Our investigation uses contemporaneous photometric and chromospheric HK emission time series measurements from the Lowell and Mount Wilson Observatories, and comparable solar data. We find that the photometric and HK variability of the stars in our sample can be related to their average level of chromospheric activity by power laws. The photometric variability of the Sun may be somewhat subdued for its average activity level. We find that the younger, more active stars in our sample tend to become fainter as their HK emission increases, whereas the older, less active stars tend to become brighter as their HK emission increases, as the Sun does during its activity cycle.

The effects of 0.15% quasi steady-state end-tidal isoflurane on the contrast sensitivity of five healthy volunteers were investigated by measuring their performance in computer generated letter discrimination tasks. A series of letters were displayed on a computer screen so that the luminance of the letter differed from that of the background. Two protocols were used: in the static protocol, the letter remained displayed on the screen until the subject responded, whereas in the dynamic protocol, the letter was displayed for 1/72 s only. Isoflurane significantly decreased contrast sensitivity in both protocols in all subjects.

Analysis of the disk-integrated phase curves of Io's leading and trailing hemispheres, as derived from combined groundbased and Voyager spacecraft measurements, shows that Io's leading side is more porous than its trailing hemisphere (assuming a globally uniform particle grain size distribution) and that the material of the trailing side is more opaque at 0.47 and 0.55 μm than the material of the leading hemisphere. The scattering nature of the leading hemisphere particles in the optically active layer of the regolith demonstrates both forward and backward scattering components. At 0.47 μm the forward scattering component is larger in amplitude than the backward scattering component, whereas at 0.55 μm they are nearly equivalent. No large phase angle data was available to adequately constrain the scattering behavior of the trailing hemisphere regolith. Measures of the geometric albedo are higher for the leading hemisphere than for the trailing hemisphere. Leading hemisphere geometric albedos are ∼0.7 to ∼0.85 at 0.47 and 0.55 μm, respectively. Trailing hemisphere albedos are ∼0.64 to ∼0.82 at 0.47 and 0.55 μm, respectively. Phase integral values for the leading hemisphere are 0.61 and 0.59 at 0.47 and 0.55 μm, respectively, which are lower than previously quoted values. Measures of the phase coefficient are higher than those previously published in the literature. No variations in Hapke parameter derived surface characteristics are observed between jovian and anti-jovian hemispheres.

UNLABELLED This study examined the effect of sevoflurane on spontaneous renal sympathetic nerve activity (RSNA), A delta- and C-fiber-mediated somatosympathetic reflexes, and hemodynamic changes in anesthetized dogs. RSNA, and A delta and C reflexes evoked by electrical stimulation of the radial nerve were observed in multifiber recordings of efferent activity in renal sympathetic nerves. Sevoflurane was administered at 1%, 2%, 3%, and 4% end-tidal concentrations for periods of 20 min. The mean A delta reflexes decreased by 20%, 39%, and 54% (P < 0.05 to < 0.01), and the C reflexes decreased by 38%, 62%, and 74% (P < 0.05 to < 0.01) at concentrations of 2%, 3%, and 4%, respectively. The relatively greater effect on C reflexes was significant (P < 0.05) and comparable with the effect of mu-opioids. There was no change in mean RSNA, heart rate (HR), and cardiac output (CO) up to 3% sevoflurane, but these decreased by 36%, 24%, and 13% (P < 0.05), respectively, at 4% sevoflurane. Sevoflurane 1%-4% caused a virtually linear reduction in systemic vascular resistance (SVR) from 7% (P < 0.05) to 44% (P < 0.05), together with a reduction in mean arterial pressure (MAP) that was significant for concentrations greater than 2%. The results indicate that sevoflurane causes a greater depression of C compared with A delta reflexes, and that the reduction in MAP was entirely due to a decrease in SVR up to 3%, whereas at 4% sevoflurane, reductions in sympathetic activity, HR, and CO also contributed its depressor effect. IMPLICATIONS The relatively greater depressant effect of sevoflurane on C compared with A delta nociceptive somatosympathetic reflexes is similar to mu-opioids. The hypotensive effect of sevoflurane was significant at 2% concentration, whereas heart rate, cardiac output and sympathetic activity were reduced only at concentrations greater than 3%.

We have monitored the Sun through a large portion of the near-IR, optical, and near-UV spectrum since late 1993 as part of our long-term observing program with the Solar-Stellar Spectrograph (SSS) at Lowell Observatory. In this paper we present our database through early 1997, which covers the end of solar cycle 22 and the first months of cycle 23. Our goals in this paper are fourfold: (1) to establish the absolute consistency of our data using an automated, completely objective reduction protocol, (2) to establish a calibration to physical flux across the entire SSS spectrum for our solar data, (3) to examine the record of the main chromospheric activity indicator, Ca II K, in our data, and (4) to search for the Sun's rotational signal in our data set, to the end that clear detection of the solar rotation at activity minimum would bode well for our ability to detect rotational signals in other, more active stars. Further analysis and modeling of these solar data will appear in forthcoming papers in this series.

We describe the first experiments to relate the cerebral kinetics of isoflurane (determined by fluorine magnetic resonance spectroscopy) to cerebral function. Using a surface receive coil we found two-compartment kinetics within the head with equilibrium half-times of 3.5 min and approximately 1 h with respect to expired isoflurane concentrations. Using critical fusion flicker frequency as an objective measure of the cerebral effect of isoflurane, we found evidence to identify the fast component as the brain. Responsiveness to command was lost at a brain partial pressure of 0.3% isoflurane. We conclude that the measured cerebral kinetics of isoflurane exactly matched the predictions of the classical perfusion-limited model.

We have investigated the effect of temperature on the blood-gas solubility of desflurane, sevoflurane, enflurane and halothane. Blood was equilibrated with gas mixtures of known composition in open cuvette or closed flask tonometers over a temperature range of 29-39 degrees C, and the concentration of each anaesthetic in blood was measured at 37 degrees C by repeated headspace analysis using a gas chromatograph. Solubility increased by 5.4% of the solubility at 37 degrees C for each degree that equilibration temperature was reduced. This result was true for all anaesthetics in all blood samples, and is in keeping with results for other volatile anaesthetics.

Hubble Space Telescope imaging of Neptune in 1994, 1995, and 1996 reveals changes in atmospheric features. Dark spots at 467 nm near latitude +31° were present in both 1994 and 1995, but absent from images in March 1996. However, a larger data set in August 1996 (Sromovskyet al., Bull. Am. Astron. Soc.28,1077, 1996) revealed a dark spot. The features resemble the Great Dark Spot present during the Voyager encounter in 1989 in size, shape, and contrast. Dark spots occur near the single brightest 619- and 889-nm features visible on the planet at that time. Methane-band clouds in the northern hemisphere were a factor of 6 brighter than the surrounding atmosphere in 1994, but only a factor of 2 brighter in 1995 and 1996. The pattern of zonal bands on Neptune was stable from 1994 to 1996, but differed from that seen by Voyager in 1989 when a prominent dark band from planetographic latitudes −40° to −68° dominated at blue wavelengths. In 1994–1996, this band was weaker and extended only from −55° to −70°, perhaps explaining the 0.06-mag brightening of Neptune between 1989 and 1994. Bright methane clouds generally appear at specific latitudes, but the active latitudes change from −25° in 1989 to −30° and −46° in 1994. The region near +30° was active in both 1989 and 1994–1996. We confirm the general shape and stability of the zonal wind profile measured by Voyager, revising previous measurements with more accurate values and filling in latitudes +38°, −30°, and −31° where no clouds had previously been seen.

Using differential Stromgren b, y photometry, we monitored the brightness variations of 41 program stars and their 73 comparison stars from 1984 through 1995. The predominantly main-sequence program stars spanned ranges of temperature and mean chromospheric activity centered on solar values. About 40% of all the stars showed measurable variability, typically at levels below 0.01 mag (~1%), on both night-to-night and year-to-year timescales. The variability correlated with mean chromospheric activity and advancing spectral type. We present differential light curves and statistical descriptions of our observations.

New measurements of Titan's hemispheric brightness asymmetry from HST images from 260 to 1040 nm show that the contrast is strongest near 450 nm (blue) and, with the opposite sign, at 889 nm (methane band). Comparison with a full Titan year of disk-integrated albedo data indicates that the seasonal cycle in asymmetry is smooth, but is insufficient to explain the variation in albedo, and a twice-per-year global albedo enhancement 50% larger than the hemispheric asymmetry amplitude is required, as noted by other workers. We also report measurements of limb-darkening (strongest at red wavelengths) and note that the transition zone between the “hemispheres” lies in the northern, brighter hemisphere at present. Comparison of models to the HST data set indicates that a change in aerosol number density above 70 km, and largely below 120 km, is the likely mechanism and is probably driven by aerosol transport by meridonal and vertical winds.

We have developed a simple, reliable method for rapid analysis of the partial pressure of volatile anaesthetic agents, based on a two-stage, head-space analysis. It is designed to solve the problems associated with reduced solubility of modern anaesthetics. After equilibration and analysis of a 2-ml sample of blood at 37 degrees C, 1 ml is transferred to another vial for a second equilibration. This ensures that there is no vapour in the headspace before the second equilibration. Measurements were performed on human blood samples equilibrated with 1% sevoflurane, 2.5% isoflurane or 3% desflurane in a tonometer. The mean error in the sample measurements was -2.3% of the tonometer reading and the 95% confidence interval for an individual measurement was +/- 8.5%. Blood samples may be stored overnight without any significant change in the results.

We describe a three-compartment model (shunt and two perfused compartments) to analyse the relationship between inspired oxygen (FIO2) and arterial oxygen saturation (SaO2) in terms of pulmonary shunt and ventilation-perfusion ratio (VA/Q). The program was tested using 24 exact datasets, each with six pairs of FIO2 and SaO2 data points with known VA/Q and shunt, generated by a complex calculator of gas exchange. Additional datasets were created by adding noise and rounding the exact sets, and by reducing the number of data points per dataset. The importance of the oxyhaemoglobin dissociation curve and the arterio-venous difference in oxygen content (avDO2) were also tested. Analysis using the three compartment model was more accurate than the two compartment model and less affected by data degradation. The absolute error in shunt estimation was never more than 2.2 % for the exact and rounded datasets, but the error in VA/Q estimation was −29 to 19 % of the true value (10th–90th centiles). The characteristics of the well-ventilated compartment were not determined accurately. At extremes of cardiac output, an assumed value of avDO2 resulted in significant errors. It is probably advantageous to correct for foetal haemoglobin in neonatal datasets. Analysis of FIO2 versus SaO2 datasets using a three compartment model provides accurate estimates of shunt and VA/Q when arterio-venous difference in oxygen content is known. The estimates may have value as objective measures of gas exchange, and as a visual guide for oxygen therapy.

Pre-operative hypoalbuminaemia is associated with worse outcomes after non-cardiac surgery, but it has only recently been considered as a predictor of outcome in cardiac surgery. A multivariate analysis of data routinely collected from 400 patients undergoing cardiac surgery was undertaken, comprising pre-operative routine blood tests (serum concentrations of albumin, creatinine, alanine transaminase, alkaline phosphatase, bilirubin and haemoglobin, and white cell and platelet count), diabetic status, left ventricular function, gender, ethnicity, body mass index and age. Indices of outcome were death and length of stay (LoS) in cardiac intensive care and hospital. Eight percent of patients had baseline severe hypoalbuminaemia (serum albumin less than 30 g.L−1): these patients had longer intensive care and hospital stays and were more likely to die. Multivariate analysis revealed the best combination of predictors of length of hospital stay for the first 200 patients to be age, serum creatinine concentration, severe hypoalbuminaemia and diabetic state. However, in the second cohort of 200 patients, the same combination of predictors was not successful in predicting LoS in hospital.

We present a summary of measurements of the atmospheric transparency over Flagstaff, Arizona, USA, made from 1972 to 1996. This period includes two major volcanic eruptions and two periods we believe are free from volcanic influence. The two eruptive periods show general similarity in history, although some differences are noted. Comparison of the two “clear” periods shows some deterioration in the tranparency over Lowell Observatory on a time scale of a decade.

Summary We have examined the predictability of inspired desflurane concentration during low-flow anaesthesia using a to-and-fro breathing system. Twenty-two adult patients requiring mechanical ventilation of the lungs during surgery took part in the study. Using a fresh gas flow of 1 l.min1, the ratio of inspired desflurane concentration to desflurane vaporizer setting was found to be approximately 0.75 after 9 min of anaesthesia and at 2 l.min1 fresh gas flow the ratio was approximately 0.9 after 2 min of anaesthesia. These ratios were maintained throughout the procedure, except for a few minutes following each change in vaporizer setting.

Patients undergoing cataract surgery using peribulbar block were allocated randomly to self-administer doses of either midazolam 0.1 mg or propofol 3.3 mg without a lock-out facility; in the control group the syringe was charged with saline, not as a placebo, but to "blind" the surgeon and the nurse observer. For midazolam and propofol, median doses were 2.54 (0.1-6.0) mg and 87.4 (0-145) mg, respectively. Patient-controlled sedation significantly reduced the level of anxiety, with median visual analogue anxiety scores in the midazolam, propofol and saline groups of 5 (0-38) mm, 5 (0-25) mm and 15 (0-92) mm, respectively (P0.05). Some patients did not administer the sedative when available while others in the saline group would have benefited from anxiolytic drugs. While both drugs prevented an increase in heart rate, only midazolam prevented an increase in arterial pressure during surgery.