Average Relative Change Research Articles

Stem electrical properties associated with water stress conditions in olive tree

The analysis of the electrophysiological activity of plants permits a real-time information of the plant status (e.g. light availability and water stress). However, even though it is clear that the role of the electrical signals in plant is crucial, especially in processes involving the propagation of rapid signals, a systematic approach for the interpretation of the electrical patterns is still missing. In this work a multi-electrodes approach has been applied to study the electrical signals in olive trees plants subjected to three different level of water stress. In particular, by using specific water irrigation regimes, a control group, a mid/mild stressed group and a high stressed group have been monitored and subsequently subjected to a long period of prolonged drought stress. Physiological parameters and electrical activity have been continuously monitored for the whole experiment to highlight any correlation between the electric signal and the water stress. Our results showed that it has been possible to differentiate the electric signals related to drought conditions of different intensity (i.e. control, mild and high). In particular we have found that the average daily relative electrical resistance change, the opposite of the electrical conductance, is directly related to the drought stress whilst the signal variance increases during the period of main water stress. Additionally, a proposed signal classification system has been successfully able to detect the absence/presence of stress and to effectively recognize daily class samples (93 % control, 76 % mild and 80 % high). The set-up could provide a useful tool for monitoring water conditions in plants and has several potential applications for sensor and automatic system in greenhouse or field able to monitor directly the plant water status.

Update of national diagnostic reference levels for adult CT in Switzerland and assessment of radiation dose reduction since 2010.

To update the national diagnostic reference levels (DRLs) for adult CT in Switzerland using dose management software and to compare them to the previous Swiss DRLs from 2010. CT dose data from 14 radiological institutes with a total of 50 CT scanners were collected with locally installed dose management software between 2014 and 2017. Data were assigned to 15 defined master protocols. Data cleaning steps were developed and adjusted individually for each participating institute and protocol. The DRLs for each master protocol were calculated as the 75th percentile of the distribution of the median volume computed tomography dose index (CTDIvol) and dose-length product (DLP) values per CT scanner. In total, 220,269 CT exams were available after data cleaning. Updated DRLs showed a clear trend towards lower doses compared with previous DRLs. The average relative change in the DRLs for CTDIvol was - 30% (0 to - 47%) and - 22% for DLP (+ 20 to - 40%). The largest relative decrease in the DRL for DLP was observed for the cervical spine protocol (- 40%), the two chest protocols (chest, - 37%; and exclusion of pulmonary embolism, - 33%), and the two neck protocols (neck, - 32%; and carotid angiography, - 28%). The DRLs for other protocols, for example the head and the abdomen-pelvis protocol, showed smaller relative changes (- 11% and - 17%). The updated national DRLs are substantially lower than the previous values from 2010, demonstrating technological progress and the efforts of the radiological community to lower CT radiation exposure. • Dose management software allows the establishment of DRLs based on big data. • Updated Swiss DRLs for adult CT are substantially lower compared with those from 2010. • Swiss DRLs are low compared with other national DRLs.

Brain volume reduction after whole-brain radiotherapy: quantification and prognostic relevance.

Recent studies have questioned the value of adding whole-brain radiotherapy (WBRT) to stereotactic radiosurgery (SRS) for brain metastasis treatment. Neurotoxicity, including radiation-induced brain volume reduction, could be one reason why not all patients benefit from the addition of WBRT. In this study, we quantified brain volume reduction after WBRT and assessed its prognostic significance. Brain volumes of 91 patients with cerebral metastases were measured during a 150-day period after commencing WBRT and were compared with their pretreatment volumes. The average daily relative change in brain volume of each patient, referred to as the "brain volume reduction rate," was calculated. Univariate and multivariate Cox regression analyses were performed to assess the prognostic significance of the brain volume reduction rate, as well as of 3 treatment-related and 9 pretreatment factors. A one-way analysis of variance was used to compare the brain volume reduction rate across recursive partitioning analysis (RPA) classes. On multivariate Cox regression analysis, the brain volume reduction rate was a significant predictor of overall survival after WBRT (P < 0.001), as well as the number of brain metastases (P = 0.002) and age (P = 0.008). Patients with a relatively favorable prognosis (RPA classes 1 and 2) experienced significantly less brain volume decrease after WBRT than patients with a poor prognosis (RPA class 3) (P = 0.001). There was no significant correlation between delivered radiation dose and brain volume reduction rate (P = 0.147). In this retrospective study, a smaller decrease in brain volume after WBRT was an independent predictor of longer overall survival.

Characterizing the Inflammatory Response to a High‐fat Meal in Healthy Adults: A Systematic Review

BACKGROUNDInflammation is a prominent feature of many chronic diseases, with poor diet being one likely inflammatory stimulus. Specifically, a single high‐fat meal (HFM) has been shown to increase inflammation, although there is currently no consensus regarding the specific changes of many of the pro‐inflammatory markers that are frequently assessed after a HFM. A synthesis of previous research investigating postprandial inflammation, with particular attention to the specific features of the response, would inform future research and advance clinical understanding.PURPOSEThe aim of this systematic review was to objectively describe the postprandial timing and magnitude of changes of five common inflammatory markers: interleukin (IL)‐6, C‐reactive protein (CRP), tumor necrosis factor (TNF)‐α, IL‐1β, and IL‐8.METHODSTen relevant databases were searched using a comprehensive search strategy, yielding 494 results, of which 47 articles met the pre‐established inclusion criteria: 1) healthy men and women age 18–60 years; 2) consuming a single HFM (≥30% fat, ≥500 kcal); and 3) assessing relevant inflammatory markers post‐meal for ≥2 hours. Study inclusion was assessed and agreed upon by two independent reviewers.RESULTSThe only marker found to consistently change (increase) in the postprandial period was IL‐6, increasing in 71% (32/45) of included studies. On average, IL‐6 was found to start at a baseline of ~1.4 pg/mL and peak at ~2.9 pg/mL approximately 6 hours post‐HFM (an average relative change of ~150%). There was a moderate but significant negative correlation (r = −0.38, p = 0.04) between percent change in IL‐6 from fasting to post‐meal with mean participant age across studies. Post‐meal IL‐6 change was not significantly correlated (p &gt; 0.05) with percent fat in the test meal (r = −0.27), kcal in the test meal (r = 0.24), or mean participant BMI (r = −0.13). C‐reactive protein, TNF‐α, IL‐1β, and IL‐8 did not change significantly in 79% (23/29), 68% (19/28), 67% (2/3), and 75% (3/4) of included studies, respectively.CONCLUSIONOur results suggest that the postprandial inflammatory response to a HFM should no longer include the commonly assessed markers CRP and TNF‐α (and potentially IL‐1β and IL‐8) in healthy humans younger than 60 years of age. However, future research should further investigate the role of IL‐6 in the postprandial period, as it routinely increases, even in health. We assert that the findings of this systematic review regarding markers of inflammation in the postprandial period will considerably aid in informing future research and advancing clinical knowledge.Support or Funding InformationNone

Identical high- K three-quasiparticle rotational bands

A comprehensive study of high-K three-quasiparticle rotational bands in odd-A nuclei indicates the similarity in $\gamma$ -ray energies and dynamic moment of inertia $\Im^{(2)}$ . The extent of the identicality between the rotational bands is evaluated by using the energy factor method. For nuclei pairs exhibiting identical bands, the average relative change in the dynamic moment of inertia $\Im^{(2)}$ is also determined. The identical behaviour shown by these bands is attributed to the interplay of nuclear structure parameters: deformation and the pairing correlations. Also, experimental trend of the $ I(\hbar)$ vs. $\hbar \omega$ (MeV) plot for these nuclei pairs is shown to be in agreement with Tilted-Axis Cranking (TAC) model calculations.

0300: Course of vascular obstruction after pulmonary embolism as assessed by ventilation-perfusion lung scan follow-up

We investigated the course of residual pulmonary vascular obstruction (RPVO) from discharge up to 3 – 6 months after pulmonary embolism (PE). Prospective registry including 202 consecutive patients with PE who survived the acute phase (high risk PE: 12.4%, intermediate-risk: 65.8%, and low- risk: 21.8%). Patients with a prior history of chronic pulmonary disease were excluded. Ventilation-perfusion (V/Q) lung scan was performed in all patients before discharge, and again at follow-up (between 3 and 6 months after discharge). Treatment was in accordance with current guidelines. Evolution of RPVO was determined as the relative change in lung perfusion (in %) between discharge and follow-up V/Q scans. Between both lung scans, RPVO decreased from 29.1±15% to 10.9±11.4%, with an average relative change of 61.7±33.4%. Overall, 49 patients (24.2%) presented a full resolution of lung perfusion. Relative change in RPVO was <50% in57 (28%), including 18 (8.9%) patients who showed no modification on lung scan. The relative change in RPVO was constant, regardless of the level of RPVO at discharge (p=0.07). Patients who presented full resolution on the second lung scan (n=49) had significantly lower RPVO at discharge as compared to those without full resolution (21.7±10.1% vs. 31.4±16.0% respectively, p<0.001), and almost 75% of those with full resolution had RPVO<30% at discharge. Multivariate logistic regression showed that high-risk PE and right ventricle (RV) to left ventricle (LV) ratio (by quartiles) at discharge were independently related to unfavorable course of RPVO during follow-up (high-risk PE: OR 3.6, 95% CI 1.54-8.43, p<0.001; RV/LV ratio: OR 3.42, 95% CI 1.12-9.45, p=0.03). Our findings suggest that systematic lung scan follow-up should not be considered after PE, except in patients with high-risk PE or those with echocardiographic signs of RV pressure overload at discharge.

On the assessment of time-resolved diffraction results.

Data collected during dynamic structure pump-probe crystallography experiments require appropriate indicators of agreement and tools to visualize the electron-density distribution changes. Agreement factors based on the ratio of intensities R with and without the external perturbation are shown to be analogous to the R1 and wR2 R factors widely used in standard crystallographic refinements. The η-based R factors, normalized by the average relative intensity change, are significantly larger than R-based values. It is shown that the relative intensity change η-based R factors are not suitable for comparing different data sets. Fourier photodifference maps allow the visualization of the externally induced structural changes in the crystal, but also can be used during refinement to observe residual peaks not yet accounted for by the model and thus monitor the progress of the refinement. The photodeformation maps are a complementary tool to confirm the validity of the final model. Photodeformation maps with equalized laser-on and laser-off thermal motion are used to highlight the structural changes.

The effects of excluding treatments from network meta-analyses: survey

Objective To examine whether the exclusion of individual treatment comparators, including placebo/no treatment, affects the results of network meta-analysis.Design Survey of networks with individual trial data.Data sources PubMed and communication...

Intentional Computed Tomography-based Oversizing in Balloon-expandable Transcatheter Aortic Valve Implantation - Incidence of Paravalvular Regurgitation and Post-deployment Geometry

Ziele: To evaluate the outcome in regard to paravalvular regurgitation and post-deployment geometry of intentional computed tomography (CT)-based oversizing of Transcatheter Heart Valves (THV) in Transcatheter Aortic Valve Implantation (TAVI) using pre- and post-deployment dual-source CT. Methode: Seventy-nine patients with severe aortic stenosis (mean age 81 ± 8 years, mean aortic valve area 0.69 ± 0.18 cm2) underwent retrospectively gated DSCT for THV sizing prior to TAVI. Aortic annulus dimensions were quantified by means of planimetry and area-derived diameter calculation (calculated average annulus diameter, CAAD = 2 x (area/pi) at the level of the basal attachment points of the aortic cusps during systole. THV selection was CAAD-based (EdwardSAPIEN XT 23 mm THV for CAAD <22mm, 26mm THV for CAAD 22–25mm, 29mm THV for CAAD >25 mm). Post-deployment CT was performed in 70 patients. Stent-unfolding was assessed planimetrically at the inlet, outlet and level of the native annulus. Relative oversizing and relative changes in annulus dimensions were calculated. Ergebnis: Average pre-deployment CAAD was 24.1 ± 1.7 mm, average post-deployment CAAD was 23.9 ± 1.5 mm (p = n.s.). Average relative change in CAAD was -0.4 ± 3.4%. Mean relative oversizing was 9.2 ± 4.8%. Mean diameter at the THV outlet was significantly larger than at the THV inlet (24.5 ± 1.7 mm vs. 23.9 ± 1.6 mm, p<0.001). Mild to moderate paravalvular regurgitation was observed in 6 patients (9%). There was no moderate or severe paravalvular regurgitation or uncontained aortic root rupture. Schlussfolgerung: Intentional oversizing of the THV based on an area-derived annulus diameter in CT and an adapted incremental sizing scheme is safe and is associated with a lower incidence of relevant paravalvular regurgitation, as compared to published landmark trials with echocardiography-based THV-sizing.

Effects of ROI Placement on PET-Based Assessment of Tumor Response to Therapy

Purpose. Quantitative PET response assessment during therapy requires regions of interest (ROI). Commonly, a fixed-size ROI is placed at the maximum uptake point in the pretreatment study. For intratreatment, the ROI is placed either at the maximum uptake point (ROIpeak) or at the same location as the pretreatment ROI (ROIsame). We have evaluated the effects of the ROI placement on response assessment. Methods. PET scans of 15 head and neck cancer patients were used to evaluate the effects of the two ROI methods on response assessment. Results. The average intratreatment ROIpeak uptake was 13.4% higher than the ROIsame uptake (range −14% to 38%). The average relative change in ROIpeak uptake was 7.9% lower than ROIsame uptake (range −5% to 36%), resulting in ambiguous tumour classification in 19% of the tumours. Conclusion. Quantitative PET response assessment using a fixed-size ROI is sensitive the ROI placement. The difference between ROIpeak and ROIsame could be substantial resulting in ambiguous response assessment. Although the fixed-size ROI is simple to implement, it is also prone to the limitations and should be used with caution. Clinical trial data are necessary to establish reliable thresholds for fixed-size ROI techniques and to evaluate their efficacy for response assessment.

Temporal Trends in Ischemic and Hemorrhagic Strokes in Northern Italy: Results from the Cardiovascular Monitoring Unit in Northern Italy Population-Based Register, 1998–2004

Background: We compared rates and case fatality from a population-based stroke register in Northern Italy between 1998 and 2004 to assess changes over time and to evaluate changes in case diagnosis and management. Methods: The WHO Multinational Monitoring of Trends and Determinants in Cardiovascular Disease criteria were used to identify suspected fatal or nonfatal events occurring among residents 35–74 years of age. Data on in-hospital treatments, symptoms and diagnostic tools were extracted. Out-of-hospital deaths were also investigated. The annual average relative change (ARC) in death rate, attack rate and case fatality were derived from Poisson models. Results: Death rates due to ischemic stroke (IS) decreased [men: ARC –12.7, 95% confidence interval (CI) –21.3 to –3.2; women: ARC –14.0, 95% CI –23.3 to –3.5]. These reductions are attributable to decreases in case fatality; attack rates of nonfatal IS increased (men: ARC 3.6, 95% CI 0.5–6.7; women: ARC 4.1, 95% CI 0.0–8.2). IS patients showed a higher prevalence of dyslipidemia and hypertension and underwent MRI more frequently in 2004. Both findings may explain the increased proportions of less severe cases. Case fatality and attack rates for hemorrhagic strokes (HS) were stable, with an observed increased prevalence of patients under anticoagulant/antiplatelet treatments. Conclusions: In this low-IS-incidence population, death rates decreased substantially during the investigated period. More accurate diagnostic tools increase the probability of detecting less severe cases. HS remains a frequently fatal disease with a stable incidence.

Statistical mechanics of the international trade network

Analyzing real data on international trade covering the time interval 1950-2000, we show that in each year over the analyzed period the network is a typical representative of the ensemble of maximally random weighted networks, whose directed connections (bilateral trade volumes) are only characterized by the product of the trading countries' GDPs. It means that time evolution of this network may be considered as a continuous sequence of equilibrium states, i.e., a quasistatic process. This, in turn, allows one to apply the linear response theory to make (and also verify) simple predictions about the network. In particular, we show that bilateral trade fulfills a fluctuation-response theorem, which states that the average relative change in imports (exports) between two countries is a sum of the relative changes in their GDPs. Yearly changes in trade volumes prove that the theorem is valid.

Measurement of endogenous acetone and isoprene in exhaled breath during sleep

This explorative study aims at characterizing the breath behavior of two prototypic volatile organic compounds, acetone and isoprene, during normal human sleep and to possibly relate changes in the respective concentration time courses to the underlying sleep architecture. For this purpose, six normal healthy volunteers (two females, four males, age 20–29 years) were monitored over two consecutive nights (the first one being an adaption night) by combining real-time proton-transfer-reaction mass spectrometry measurements from end-tidal exhalation segments with laboratory-based polysomnographic data. Breath acetone concentrations increased overnight in all measurements, with an average relative change by a factor of up to 4 (median 2.5). Nighttime concentration maxima were usually recorded 2–3 h before lights on. For breath isoprene, a nocturnal increase in baseline concentrations of about 74% was observed, with individual changes ranging from 36–110%. Isoprene profiles exhibited pronounced concentration peaks, which were highly specific for leg movements as scored by tibial electromyography. Furthermore, relative to a linear trend, baseline isoprene concentrations decreased during the transition from the NREM to the REM phase of a complete sleep cycle.

Recent epidemiologic trends of diabetes mellitus among status Aboriginal adults.

Little is known about longitudinal trends in diabetes mellitus among Aboriginal people in Canada. We compared the incidence and prevalence of diabetes, and its impact on mortality, among status Aboriginal adults and adults in the general population between 1995 and 2007. We examined de-identified data from Alberta Health and Wellness administrative databases for status Aboriginal people (First Nations and Inuit people with treaty status) and members of the general public aged 20 years and older who received a diagnosis of diabetes mellitus from Apr. 1, 1995, to Mar. 31, 2007. We calculated the incidence and prevalence of diabetes and mortality rate ratios by sex and ethnicity in 2007. We examined the average relative changes per year for longitudinal trends. The average relative change per year in the prevalence of diabetes showed a smaller increase over time in the Aboriginal population than in the general population (2.39 v. 4.09, p < 0.001). A similar finding was observed for the incidence of diabetes. In the Aboriginal population, we found that the increase in the average relative change per year was greater among men than among women (3.13 v. 1.88 for prevalence, p < 0.001; 2.60 v. 0.02 for incidence, p = 0.001). Mortality among people with diabetes decreased over time to a similar extent in both populations. Among people without diabetes, mortality decreased in the general population but was unchanged in the Aboriginal population (-1.92 v. 0.11, p = 0.04). Overall, mortality was higher in the Aboriginal population than in the general population regardless of diabetes status. The increases in the incidence and prevalence of diabetes over the study period appeared to be slower in the status Aboriginal population than in the general population in Alberta, although the overall rates were higher in the Aboriginal population. Mortality decreased among people with diabetes in both populations but was higher overall in the Aboriginal population regardless of diabetes status.

The cost impacts of a mandatory move to time-of-use pricing on residential customers: an Ontario (Canada) case-study

Using 2008 hourly electricity data from 1,020 households in Milton, Ontario (Canada), this article asks and answers two questions: ‘How do residential customers’ total costs change as the result of a mandatory move from a traditional, flat-rate pricing structure, to a time-of-use one?’; and ‘Are particular “kinds” of customers either “winners” or “losers” as a result of this move?’ In response to the first question, 45% of customers have lower bills under a time-of-use regime (as compared with what they would have paid, had the previous two-tier regime continued, with their ‘new’ consumption patterns), while 55% of customers have higher bills. For 98.2% of customers, the difference in total cost is less than 5% (either way), and the average relative change is a 0.233% increase. In response to the second question, customers that have a relatively high level of consumption in either peak periods or wintertime are, in the absence of other differences, more likely to have higher bills under a time-of-use regime. Those households that consume higher quantities of electricity are more likely to have lower bills under a time-of-use regime, as compared with the two-tier regime. The article concludes by highlighting the equity implications of this finding and by identifying areas for future research.

The value of electrical impedance tomography in assessing the effect of body position and positive airway pressures on regional lung ventilation in spontaneously breathing subjects

Functional electrical impedance tomography (EIT) measures relative impedance changes in lung tissue during tidal breathing and creates images of local ventilation distribution. A novel approach to analyse the effect of body position and positive pressure ventilation on intrapulmonary tidal volume distribution was evaluated in healthy adult subjects. Prospective experimental study in healthy adult subjects in the intensive care unit at university hospital. Ten healthy male adults. Change in body position from supine to prone, left and right lateral during spontaneous breathing and positive pressure support ventilation. EIT measurements and multiple-breath sulphur hexafluoride (SF6) washout were performed. Profiles of average relative impedance change in regional lung areas were calculated. Relative impedance time course analysis and Lissajous figure loop analysis were used to calculate phase angles between dependent or independent lung and total lung (phi). EIT data were compared to SF6 data washout measuring the lung clearance index (LCI). Proposed EIT profiles allowed inter-individual comparison of EIT data and identified areas with reduced regional tidal volume using pressure support ventilation. Phase angle phi of dependent lung in supine position was 11.7+/-1.4 degrees, in prone 5.3+/-0.5 degrees, in right lateral 11.0+/-1.3 degrees and in left lateral position 10.8+/-1.0 degree. LCI increased in supine position from 5.63+/-0.43 to 7.13+/-0.64 in prone position. Measured phi showed inverse relationship to LCI in the four different body positions. EIT profiles and phi of functional EIT are new methods to describe regional ventilation distribution with EIT allowing inter-individual comparison.

Characterization of the Cation and Temperature Dependence of DNA Quadruplex Hydrogen Bond Properties Using High-Resolution NMR

Variations in the hydrogen bond network of the Oxy-1.5 DNA guanine quadruplex have been monitored by trans-H-bond scalar couplings, (h2)J(N2N7), for Na(+)-, K(+)-, and NH(4)(+)-bound forms over a temperature range from 5 to 55 degrees C. The variations in (h2)J(N2N7) couplings exhibit an overall trend of Na(+) > K(+) > NH(4)(+) and correlate with the different cation positions and N2-H2...N7 H-bond lengths in the respective structures. A global weakening of the (h2)J(N2N7) couplings with increasing temperature for the three DNA quadruplex species is accompanied by a global increase of the acceptor (15)N7 chemical shifts. Above 35 degrees C, spectral heterogeneity indicates thermal denaturation for the Na(+)-bound form, whereas spectral homogeneity persists up to 55 degrees C for the K(+)- and NH(4)(+)-coordinated forms. The average relative change of the (h2)J(N2N7) couplings amounts to approximately 0.8 x 10(-3)/K and is thus considerably smaller than respective values reported for nucleic acid duplexes. The significantly higher thermal stability of H-bond geometries in the DNA quadruplexes can be rationalized by their cation coordination of the G-quartets and the extensive H-bond network between the four strands. A detailed analysis of individual (h2)J(N2N7) couplings reveals that the 5' strand end, comprising base pairs G1-G9* and G4*-G1, is the most thermolabile region of the DNA quadruplex in all three cation-bound forms.

Rising incidence of pancreatic carcinoma in middle-aged and older women-time trends 1961-90 in the city of Malmö, Sweden

The city of Malmö (population 230 000), situated in the south of Sweden, is in an area which has the highest incidence of pancreatic cancer in the country. The present study was designed to assess time trends of the incidence of pancreatic cancer 1961-90. The 1314 incident cases, 651 men and 663 women, were retrieved from the Regional Tumour Register and the National Cause-of-Death Register. In 75% of cases diagnosis was based on autopsy. Twenty per cent of the these cases were first found at autopsy, being undiagnosed. The average age-standardised incidence was 20.4 per 10(5) person-years for men and 13.7 for women. The incidence was higher for men than for women in all age groups above 44 years. No change in incidence over time was observed for men. In older and middle-aged women there was however a statistically significant increase. The average relative change in women above age 64 was 1.7% per year after age adjustment and in women aged 55-64 years 2.6% per year. We have found no results indicating that this increasing incidence could be caused by detection bias as a result of changing autopsy rates during the study period and hence conclude that the observed increase is explained by a growing number of women being exposed to factors with a potential tumour-promoting or -initiating effect.

Effects of electromagnetic and plasma drag forces on the orbit evolution of dust in planetary magnetospheres

We have considered the evolution of dust orbits in a gravitational and electromagnetic field like that in the magnetosphere of Saturn. The orbits evolve due to the action of plasma drag and gyrophase drag (Lorentz force combined with a delay in charging of the dust). We calculate the average relative change in the semimajor axis, 〈 a dot /a 0〉 , and the average change in eccentricity, 〈 e dot 〉 , for different initial orbits and different plasma conditions, including cases with constant temperature and density and cases with gradients in temperature and density. Finally, we adopted a plasma model which may be appropriate for the E-ring plasma of today. This model has a cold and hot electron component and the production of secondary electrons is important, contrary to the other cases considered. It appears possible that the E-ring dust particles, if injected by Encleadus at low eccentricities, will keep their low eccentricities in today's plasma environment. This would imply that the orbits would drift slowly outward mainly due to plasma drag. Using an extensive set of different parameters, we show that in some circumstances the perturbing forces may be strongly dependent on global or local plasma conditions and/or dust properties. This implies that even moderate environmental changes could have significant effects on the evolution of Saturn's E-ring, and emphasizes the need for better in situ measurements in order to understand this diffuse ring phenomenon.

Experimental and clinical tests of the oxyconsumeter: a new oxygen uptake monitor.

The prototype of a microprocessor controlled oxygen uptake monitor oxyconsumeter developed by Draegerwerk AG, Luebeck, FRG, has been tested. The measuring accuracy of this device was assessed with laboratory bench experiments utilizing both the nitrogen dilution technique and the hydrogen combustion technique to simulate oxygen uptake (VO2). The correlation coefficient between the simulated and the measured VO2 values was 0.9989 (p less than 0.05, n = 115). The average relative error of the VO2 values was -3.32% +/- 3.88% when breathing 21 vol% oxygen and -5.58% +/- 4.53% for 70 vol% oxygen (percent of reading). This was within the range given by the manufacturer (+/- 5% for 21 vol% to less than 40 vol%, +/- 10% for 40 vol% to less than 70 vol%) with few exceptions. Furthermore the oxyconsumeter was used in clinical experiments to determine oxygen uptake during general anaesthesia. Oxygen uptake was monitored using a non-rebreathing system with an externally triggered expiratory valve. The difference between preanaesthetic reference values and values determined during anaesthesia averaged -24.8 +/- 20.1 ml/min/m2 oxygen. This average relative change of -16.0 +/- 11.5% was statistically significant in 11 of 15 cases (p less than 0.05).