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Nasal and tracheobronchial mucociliary clearance have been compared in 10 healthy subjects. Nasal clearance was measured by monitoring the rate of removal of 2 microns diameter Teflon particles, labelled with 99mTc, which had been placed in the anterior part of the nose. Tracheobronchial clearance was measured with an objective radioaerosol technique, 5 microns diameter polystyrene particles being used. With these comparable techniques there was a close correlation between the nasal mucociliary clearance rate and both the area under the tracheobronchial clearance curve from 0 to 6 hours after radioaerosol inhalation (rs = -0.94, p less than 0.001) and the area under the tracheobronchial clearance curve from 0 to 2.5 hours after inhalation (rs = -0.79, p less than 0.01). The rate of clearance of small particles from the nose may thus be a useful guide to tracheobronchial clearance in healthy individuals.

The effect of a single dose of carbamazepine (CBZ), 10 mg kg-1, on a battery of simple psychomotor tests was investigated in 12 healthy subjects (6 male, 6 female) in a balanced randomised double blind placebo controlled cross-over study. Psychomotor testing and blood sampling for total and free plasma CBZ, and CBZ 10, 11 epoxide concentration were performed at 10, 12, 14, 16, 18 and 34 h after oral dosing (23.00 h the previous evening). CBZ impaired i) critical flicker fusion threshold frequency at all time points up to 18 h (p less than 0.005); ii) total choice reaction time at 10 h (p less than 0.005) and 18 h (p less than 0.008); iii) card sorting at 14 h (p less than 0.001). No significant effect on finger tapping was noted. Subjects adjudged themselves more sedated on CBZ as compared to placebo at 12, 14 and 16 h (p less than 0.008). Plasma total and free CBZ concentrations (mean +/- SD) peaked at 10 h (8.8 +/- 0.2 mg 1-1) and 16 h (1.88 +/- 0.3 mg 1-1) after dosing respectively. CBZ 10, 11 epoxide values were all less than 10% of total CBZ concentrations and, therefore, were unlikely to contribute to the pharmacodynamic effect. Total choice reaction time was significantly more impaired in females (p less than 0.05) but no sex difference occurred with the other tests or CBZ concentrations at any time point. No significant correlations were found between individual total or free CBZ concentrations and corresponding test performances at each time point.(ABSTRACT TRUNCATED AT 250 WORDS)

This paper constructs a dynamic model of a general congestion-prone system using a nonlinear differential equation to represent the relation between throughput and the system load. Although the model is not stochastic, it can give a good approximation of the dynamics of oversaturated or undersaturated system operation. The model is used to study the stability and transient behavior of a congestion-prone system and to analyze policies for the control of congestion in a simple optimal control model.

Lung retention of insoluble Tc-99m particles was measured at 24-h and 48-h in subjects of widely varying lung function. In 10 tests out of 58, clearance between 24-h and 48-h accounted for 10 to 26% of the initial lung deposit, presumably reflecting a continuing tracheobronchial clearance. Retention was analysed relative to lung function for three groups of tests: A, mean inhalation flow rate 20–241/min (n = 17); B, 25–301/min (n = 20); C, 31–381/min (n = 21). Within each group, 48-h retention correlated strongly with forced expiratory volume in 1 s(r > 0.84, p 0.81, p < 0.001). Differences of slope and position between the regression lines for the three groups suggested 48-h retention falling (as expected) with increasing inhalation flow rate in subjects with good lung function —but not in subjects with poor lung function. A substantial fraction of 48-h retention in the latter may represent impactional deposition at tracheobronchial sites.

Oral N-acetylcysteine has been advocated as a mucolytic agent for use in chronic bronchitis. We have investigated the effects of regular use of this drug at a dose of 200 mg thrice daily for 4 weeks in nine patients with chronic bronchitis on lung function, lung mucociliary clearance and sputum viscosity in a controlled, double-blind, crossover study. No significant differences were found in lung function, mucociliary clearance curves or sputum viscosity following treatment with N-acetylcysteine compared to control or placebo measurements.

Tracheobronchial mucociliary clearance was measured with the radioaerosol technique in 25 patients with stable, mild asthma, none of whom was taking systemic corticosteroids. The results were compared with those obtained from a control group of 25 healthy subjects matched for age and sex. All patients and healthy subjects were non-smokers. Ventilatory function was significantly impaired in the asthmatic group, which resulted in a more central initial tracheobronchial deposition of inhaled radioaerosol than in the control group. Despite the shorter transit path along the ciliated airways for the tracer radioaerosol in the asthmatic group, mucociliary clearance was found to be significantly poorer than in the healthy control group. This may be important with respect to bronchial mucus plugging.

Radioaerosol measurements of mucociliary clearance have been assessed in relationship to depth of particle penetration into the lung. The tests analysed were performed with 5 μm diameter 99Tcm particles inhaled under standardised conditions but at varying inhalation flow rates. Aerosol lung penetration was assessed by (i) penetration index (PI), a ratio of outer to inner zone radioactivity determined from a gamma camera image; and (ii) alveolar deposition (AD), a measure of activity retained at 24 hours and taken to represent deposition distal to the ciliated airways. Clearance rates in 30 tests on 19 normal non-smokers under the age of 50 varied significantly with aerosol inhalation flow rate, PI and AD. A normal range varying with PI is proposed although normal inter-subject variability remains high even after allowance for PI. Nevertheless 8 out of 12 patients with stable asthma and 21 out of 24 patients with chronic bronchitis demonstrated slow clearance lying outside the Pi-based normal range.

Currently, the FCC assigns radio licences after making a determination of the public interest. Conflicting licence applications are resolved through comparative hearings. This mechanism is cumbersome and unreliable. This article analyses three alternatives: Increasing the available spectrum; an auction; or, lottery of radio licences. The analysis deals specifically with the Multipoint Distribution Service (MDS). The analysis suggests that increasing the spectrum allocation will create more assignments than will be demanded by MDS. Rough calculations suggest that auctions offer a more efficient selection mechanism. Lotteries with resale of the license are better than hearings, but not as good as auctions.

Prophylactic phenytoin (DPH) has been evaluated in 20 patients undergoing diagnostic myelography. DPH (0.75 g) was ingested at 20.00 h the night before and 0.5 g at 08.00 h on the morning of the procedure. Total DPH concentrations at myelography (mean +/- s.d.: 12.7 +/- 4.3 mg l-1; range 6.3-21.5 mg l-1) correlated with CSF values (1.3 +/- 0.46 mg l-1; range 0.7-2.2 mg l-1; r = 0.83, P less than 0.001). DPH protein binding at that time varied two-fold (9.2-18.5%) and free drug levels (1.7 +/- 0.6 mg l-1) correlated with CSF (r = 0.83, P less than 0.001) and total (r = 0.89, P less than 0.001) plasma DPH concentrations. There were significant negative correlations between patient weight (n = 17) and total (r = 0.57, P less than 0.05) and CSF (r = -0.55, P less than 0.05) DPH concentrations at myelography. Total plasma DPH levels 8 h (14.5 +/- 3.9 mg l-1; range 7.3-20.6 mg l-1) and 24 h (12.3 +/- 3.8 mg l-1; range 5.0-19.8 mg l-1) after myelography were largely within the 'therapeutic range' of 10-20 mg l-1 for the drug. No patient suffered a seizure although, in two, spike discharges were seen on a post-myelography electroencephalogram. A simple regime involving two doses of DPH would provide acceptable plasma CSF concentrations as a basis for controlled studies in seizure prophylaxis following neuroradiological investigations involving intrathecal contrast.

198-Au-gold colloid liver scans and 75-Se-selenomethionine pancreas scans in 72 patients with extrahepatic obstructive jaundice were assessed by blind marking. They were compared with liver and pancreas scans from 20 control patients and liver scans from 33 patients with diffuse liver disease. 56 per cent of the liver scans in extrahepatic obstructive jaundice showed a filling defect in the hilar region of the liver. This was most frequently seen in the most deeply jaundiced patients, and was reported in 80 per cent of patients with a serum bilirubin greater than 15 mg/100 ml. The liver scan alone cannot distinguish between different forms of extrahepatic obstructive jaundice although severe loss of left lobe uptake appeared to favour a diagnosis of carcinoma of the bile or hepatic ducts. A normal pancreas scan virtually excludes a pancreatic carcinoma as the cause of obstructive jaundice. A pancreas scan showing severely reduced uptake suggests a carcinoma of the pancreas or of the lower end of the common bile duct.

Tracheobronchial mucociliary clearance was measured in eight non-smoking patients with asthma in complete remission. The patients were symptom free and required no medication whatsoever for one to six months before assessment. Mucociliary clearance was measured with an objective, radioaerosol technique. For comparison, mucociliary clearance of eight non-smoking, healthy subjects with physical characteristics and pulmonary function similar to those of the asthmatics was also measured on two occasions. In their first assessment the healthy subjects inhaled the tracer radioaerosol under experimental conditions similar to those used for the asthmatics; in the second assessment they inhaled the radioaerosol rapidly to simulate the asthmatic pattern of deposition. Under similar experimental conditions the radioaerosol was deposited more proximally in the asthmatic subjects than in the normal subjects and the difference was statistically significant (p less than 0.01). When, however, the depth of radioaerosol lung penetration was similar in the two groups, there was evidence of a significantly (p less than 0.01) poorer mucociliary clearance six hours after radioaerosol inhalation in the asthmatic than in the healthy group. These findings raise the question whether asthma ever remits completely.

A computerised system for targeting expected monthly milk production at farm level is described. The system is run by the Economics Department of the Milk Marketing Board for Northern Ireland and utilises a database of records from their Dairy Information Service. These records are combined with a set of forecast data on calving, culling and replacement and a model for the lactation curve of the dairy cow to produce, on a cumulative basis, a comparison of target and actual milk production throughout the financial year. The system enables farmers to make a quantitative assessment of the likelihood of their herd being above or below quota at the end of any current financial year, thus allowing decisions on culling and feeding policy to be made at key points in the year.

Data on the effect on mucociliary clearance of oral high frequency oscillation is conflicting. By means of a technique to superimpose high frequency oscillation on tidal breathing, changes in mucociliary clearance during high frequency oscillation were studied in seven normal non-smokers by monitoring the clearance of inhaled radiolabelled aerosol from the lungs. After inhalation of 5 microns technetium 99m labelled particles under controlled conditions, whole lung clearance was monitored by scintillation counters half hourly for six hours with a final count at 24 hours, from which tracheobronchial deposition and clearance could be calculated. Control and high frequency oscillation studies were performed on separate days in random order. Oral high frequency oscillation was applied by a bass loudspeaker through a mouthpiece to superimpose sinewave oscillations (RMS input pressure 1.2 cm H2O, mean pressure zero) on normal breaths. On high frequency oscillation days 30 minutes of oscillation alternated with 30 min of rest. Between 3 and 4.5 hours mucociliary clearance with high frequency oscillation exceeded control by about 10% (p less than 0.05). The mean time taken to eliminate 90% of deposited radioaerosol from the tracheobronchial tree fell from 4 hours 50 minutes (range 1 h 52 min-6 h 50 min) during control to 3 hours 43 minutes (range 2 hr 28 min-5 hr 54 min) during the high frequency oscillation run (p less than 0.05). Possibly this comfortable, simple technique would be of therapeutic benefit to patients with chronic sputum retention and merits further investigation.

When two or more information sources (“experts”) provide a decision maker with information on two or more random variables, the decision maker using Bayes's rule has an opportunity to (a) update a prior about the random variables and (b) calibrate the experts. (Calibration is the process of adjusting the decision maker's likelihood about the experts' assessments.) This article presents a model for this two-way process and specializes to the case in which the experts' assessment errors have a multivariate normal density. In general, we find that variables which the decision maker and the experts regard as independent a priori will be dependent a posteriori because of dependence in the assessment errors. Formulas for posterior densities are given for the normal model. In this model the posterior density of the random variables depends on only a weighted average of the expert's means, with weights that depend on the experts' assessments of previously known quantities. I also present a special case o...

We studied eight young smokers and ten nonsmokers, to determine whether respiratory epithelial permeability to radiolabelled diethylenetriamine penta-acetate (99mTcDTPA) was related to small airway function or bronchial reactivity. Permeability was measured in inner (containing central airways) and outer lung zones by gamma camera. Lung-to-blood half-time (LB-T1/2) was corrected for blood background. Histamine was inhaled tidally (2 min inhalations) using doubling concentrations from 2 to 64 mg.ml-1. Results of small airway function tests, and of bronchial reactivity (expressed as the threshold concentration (reducing forced expiratory volume in one second (FEV1) by 2 SD), and as the percentage reduction in FEV1 after histamine 16 mg.ml-1) were similar in smokers and nonsmokers. LB-T1/2 was shorter in smokers than in nonsmokers in both inner (median (range) 21 (5.5-33) vs 63.5 (41-115) min; p less than 0.004) and outer (20.5 (5.5-30) vs 58.5 (39-105) min; p less than 0.004) zones. Neither inner nor outer zone LB-T1/2 was related to small airway function or bronchial reactivity. Bronchial reactivity and small airway tests may be abnormal in middle-aged smokers, but neither is related to the increased respiratory epithelial permeability of young smokers, in whom it appears too sensitive an index of airway integrity.

Simultaneous cerebrospinal fluid (CSF), total and free plasma valproic acid (VPA) concentrations were measured in 17 patients receiving two weight-adjusted VPA doses as seizure prophylaxis prior to diagnostic myelography or cisternography. Free drug concentrations were similar when measured by equilibrium dialysis (ED) at 37 degrees C for 24 h (Dianorm) or by a novel ultrafiltration (UF) method (EMIT freelevel system 1, SYVA) (ED:2.3-35.5 mg-1; UF:1.3-33.6 mg-1; r = 0.78, P less than 0.002). There was wide variation in total VPA concentration (39-154 mg-1) and in free fraction (ED: 3.3-25.6%; UF: 5.9-24%). Concentration dependent protein binding was not demonstrated. CSF VPA varied between 4.2 and 25.6 mg-1 and was accurately reflected by free plasma VPA concentrations (ED: r = 0.75, P less than 0.005: UF: r = 0.93, P less than 0.001). CSF concentration also correlated with the total plasma VPA (r = 0.76, P less than 0.005). The Emit freelevel system 1 provides a rapid measure of unbound VPA in the plasma which may be suitable for routine clinical use.

Forecasts of the future price and quantity of a service or commodity often ignore the dynamic interaction between demand and supply, perhaps because the economic meaning of these concepts is often rather fuzzily defined. This paper attempts to remove some of the fuzziness, and shows that the equilibrium point where supply and demand are equal has a clear interpretation. Further it argues that forecasts of the movement of the equilibrium point over time are meaningful and useful. Using the notion of equilibrium a model is constructed which forecasts simultaneously the rates of change of price and output. This model shows how a forecast is biased when the interaction between demand and supply is not included and what special assumptions are implicitly made by a forecaster who ignores it. Finally, the paper shows how uncertainty about the parameters of the model affects the estimates of the rates of change, providing uncertain estimates of price and quantity.

Quantitative indices are described for assessing the distribution of ventilation imaging agents (radioaerosols, in particular) within the lung. They have been applied to images obtained with 99Tcm aerosol particles (0.5-2.0 µm diameter) and with 81Krm gas in 12 patients with a wide range of lung function. In patients with normal lung function aerosol distribution was similar to that of 81Krm. In patients with airways obstruction, the aerosol tended to penetrate less well than 81Krm to the lung periphery and to show a less homogeneous distribution there. Quantitative analysis confirms that the aerosol technique is an effective substitute for 81Krm in patients with normal lung function. When lung function is impaired aerosol images may still be valuable particularly in confirming a diagnosis of pulmonary embolism though they must be interpreted with caution in attempting to exclude that diagnosis. It is concluded that small particle radioactive aerosols provide a readily available ventilation technique for clinical ventilation-perfusion imaging.

The 75Se-selenomethionine pancreas scan cannot differentiate between chronic pancreatitis and carcinoma of the pancreas and may--although chiefly in certain defined clinical conditions--give a false-positive result. It is also rather more time-consuming than other radioisotopic scanning procedures. Its value in clinical practice stems from the fact that all the other methods currently available for studying the pancreas have their own disadvantages. Because a normal scan is only rarely seen in patients with carcinoma of the pancreas, pancreatic scanning can be particularly useful in helping to decide which patients should, and which should not, be subjected to other procedures involving greater discomfort or risk.

In proximal decision analysis the value of a decision depends on a vector of state variables s and a vector of decision variables d in a quadratic fashion. Suppose some data, represented by a vector x, can be obtained. This paper describes a technique for using the data and develops an expression for the value of the information conveyed by the data. Because the value model is quadratic the data processing procedure uses a linear minimum-variance estimate of the conditional mean of s which depends only on the prior moments of the state vector and the noise associated with the measurement.

The Communications Act of 1934, which regulates the United States telecommunications industry, is becoming less able to deal with the changes brought by modern technology. Therefore, proposals are being made to restructure the industry. Breaking up AT&T into smaller firms would have only minor effects, since its ratio of R and D to sales has been near the median for large telephone companies. Restructuring AT&T into subsidiaries dealing at arms' length might cause a reordering of priorities toward more directly marketable and useful products, but too extensive a break-up could endanger Bell Labs' commitment to basic research. Regulation leads a firm to ignore true social value of possible products, expand into low profit markets, and favor capital-intensive over labor-intensive innovation. If regulatory lag occurs, a firm will produce cost-reducing innovation in order to increase its profit.

Although aerosol depositions in the lungs is often considered in the context of industrial hygiene, aerosols also play an important clinical role. Three principal mechanisms (inertial impaction, gravitational sedimentation and Brownian diffusion) account for the majority of aerosols deposition in the lungs. Deposition depends upon the mode of inhalation, the nature of the particles and physical characteristics of the subject inhaling the particles. Radioaerosols are widely employed in measurements of total and regional deposition, and topographical distribution may also be determined. Aerosols play an important role in the treatment of various forms of respiratory disease, with bronchodilators for the therapy of asthma being particularly important. On average only 10% of the therapeutic aerosol dose actually reaches the lungs. The rate of removal of insoluble radioaerosols deposited in the lungs may be used as an index of mucociliary transport. Aerosols are also used in a variety of other diagnostic and research procedures, particularly for ventilation scanning, alveolar clearance, measurement of alveolar permeability, and for measuring the size of pulmonary air spaces.

Smoking induced changes in the secretory cells of bronchiolar epithelium by facilitating secretion of cross linked glycoprotein mucus may influence the efficiency of mucus-cilia coupling. The functional impact on mucociliary transport in small (peripheral) airways has been studied by comparing data on aerosol deposition and clearance from symptomless cigarette smokers (30 tests, 18 subjects) with data from age matched non-smokers (30 tests, 19 subjects). Gamma camera images, assessed in terms of a penetration index comparing peripheral with inner zone deposition, indicated closely similar initial deposition in the two groups. Alveolar deposition, however, assessed in terms of particle retention at 24 hours, was significantly (p less than 0.01) less in the smokers. Given the similarity of initial deposition, this implies that an increased proportion of small conducting airways are protected by mucociliary defence in the smokers' lungs. Clearance from conducting airways of the peripheral zone in tests with relatively high peripheral deposition (14 tests on smokers, and 12 on non-smokers) nevertheless proceeded at the same rate in smokers as in non-smokers.

Tracheobronchial mucus clearance was measured in nine mild asthmatics, using an objective radioaerosol technique, on 3 separate days at intervals of 1 week. Immediately after radioaerosol inhalation, drug or placebo was administered via subcutaneous injection (SC) plus metered dose inhaler (MDI)--2 puffs. Three randomized treatments were used: saline placebo SC plus 2 mg terbutaline by MDI (1 mg per puff); 0.25 mg terbutaline SC plus placebo (propellants and surfactant only) by MDI; and double placebo. Changes in lung mucociliary clearance showed an inverse relationship to baseline clearance of both proximal and distal ciliated airways following inhaled terbutaline, whereas terbutaline SC related inversely only to baseline clearance of the distal ciliated airways. This may reflect the surface concentrations of drug, established by each route.

Modelling of inhaled particle deposition in the lungs potentially offers data relevant to assessing hazards from toxic inhaled particles, to studying mucus clearance or lung permeability by aerosol techniques, and to achieving better utilisation of drugs administered as aerosols. Analysis of published modelling studies is complicated by differing approaches to the quantitative estimation of physical factors determining deposition and by differing choices of anatomical data. Published formulae for predicting aerosol particle impaction are compared by applying them to the deposition of 5 mu m particles in the human conducting airways using the morphological data of Weibel (1963) together with information from other sources about airways branching angles. The results indicate the range of deposition estimates that may be obtained from currently available impaction formulae. All but one of the formulae considered agree in indicating maximum deposition by impaction in, or close to, the segmental or subsegmental bronchi. Data are presented to indicate how the principal physical determinants of deposition depend on particle size, inhalation flow rate and lung volume during inhalation.

A novel technique has been devised for monitoring quantitatively the inhalation of cigarette smoke into a smoker's lungs, using the isotope krypton-81 m as a tracer for the smoke.

Two formulae for particle deposition by sedimentation have been applied to three symmetric (or quasi-symmetric) models of the human conducting airways. For inhalation at 201 min−1, calculations based on the tabulated data of the Weibel model predicted a cumulative deposition probability of 18–23% for sedimentational deposition in the small airways (taken as generations 8–15 inclusive). Similar values, although with differing patterns of distribution, were calculated for the other two airways models. Scaling the model data from a lung volume of 4800-2400 ml reduced predicted sedimentational deposition by approximately 13. Several workers have suggested that clearance from the lung of insoluble particles deposited on the small airways takes longer than three hours. Clearance of 99mTc-labelled insoluble 5 μm particles from the lung was measured in ten normal non-smoking subjects after inhalation at 20 and at 481 min−1. In both cases, clearance over the period of 3–24 h following inhalation accounted for only 10% of the initial lung burden. It is suggested therefore that either (i) model calculations based on applying deposition formulae to anatomical model data may overestimate sedimentational deposition in the small airways or (ii) that many particles deposited at small airways sites may fail to be removed from the lungs by mucociliary transport.

Two analytic models of a store-and-forward communications network are constructed, one to find the optimal message routing and the other to illustrate the equilibrium (stationary state) maintained by an adaptive routing algorithm. These models show that adaptive routing does not satisfy the necessary conditions for an optimal routing. Adaptive routing tends to overuse the direct path and underuse alternate routes because it does not consider the impact of its current routing decision on the future state of the network. The form of the optimality conditions suggests that a modification of the adaptive algorithm will result in optimality. The modification requires the substitution of a quadratic bias term instead of a linear one in the routing table maintained at each network node. Simulation results are presented which confirm the theoretical analysis for a simple network.

Economists, like other forecasters, share knowledge, data and theories in common. Consequently, their forecast errors are likely to be highly dependent. This paper reports on an empirical study of 16 macroeconomic forecasters. Composite forecasts are computed using a sequential weighting scheme that takes dependence into account; these are compared to a simple average and median forecasts. A within-sample composite is also calculated. Both these methods perform significantly better than the average or median of the forecasts. This improvement in accuracy is apparently because the dependence between the forecasters' errors is so high that the optimal composite forecasts sometimes lie outside the range of the individual forecasts.

The absorption of (47)Ca Cl(2) taken with a milk and porridge meal was measured in normal subjects, patients with a partial gastrectomy, and patients with malabsorption. The addition of palm oil to the meal depressed calcium absorption, whereas the addition of medium-chain triglyceride had no effect. The contrasting effect of the two fats on calcium absorption was most marked in patients with a partial gastrectomy and least marked in patients with malabsorption. In patients with malabsorption, impairment of calcium absorption was most marked in the patients with a significant increase in faecal fat excretion. Absorption of calcium was greater in patients with a partial gastrectomy than in normal subjects.

A new test of pancreatic exocrine function is described in which radioselenium is measured in duodenal aspirate after an intravenous injection of (75)Se-selenomethionine and administration of a Lundh test meal. Duodenal (75)Se activity gave good separation between normals and subjects with disease of the exocrine pancreas and correlated well with trypsin levels in the aspirate.

About 500 antiprotons in a partially purified antiproton beam have been observed to enter the 30-in. propane bubble chamber. An arrangement of counters identified the antiproton events, thus reducing scanning to a minimum and also providing a sample of antiprotons free of scanning bias. The antiprotons entered the propane at a kinetic energy of 220 Mev and were brought to rest. Scattering and annihilation interactions in both hydrogen and carbon have been observed as a function of antiproton energy. Differential scattering cross sections have been obtained, and the following total cross sections have been measured for antiproton kinetic energies, $T$, in the ranges 75 to 137.5 Mev and 137.5 to 200 Mev: The above results show satisfactory agreement with the Ball-Chew theory where comparison can be made.

Measurements of the p-p, elastic, inelastic, and charge-exchange cross sections are reported for antiproton energies of 534, 700, 816, 948, and 1068 Mev. The total cross section remains large with respect to N-N cross sections in the same energy range. A schematic diagram of the experimental setup is given. The 6-Bev internal proton beam of the Bevatron impinged on a carbon or polyethylene target at one of three different target positions. (W.D.M.)

A technique has been developed which allows the position of the upper gastrointestinal tract, as determined radiographically, to be superimposed on the pancreatic photoscan, performed after an injection of (75)Se-selenomethionine. Results of the technique applied to 27 ;abnormal' and 23 ;normal' subjects are described. The importance of the additional information gained by the combined technique is discussed in terms of normal variation and increased diagnostic yield, and the situations in which it was found most useful are described. The addition of correlated duodenography rendered scan reporting more objective in 50% of cases.

As measured by whole body retention of isotopic calcium given in milk, absorption of calcium was impaired in 10 patients with chronic parenchymal non-biliary liver disease who were icteric. Mean absorption was normal in 15 patients with parenchymal liver disease who were anicteric although some individual patients absorbed less than any of the controls. Depressed absorption of calcium was seen in 10 patients with primary biliary cirrhosis and seven patients with intra- or extra-hepatic biliary obstructive disease. The most likely cause for this malabsorption is reduced bile salt secretion into the intestinal lumen which impairs vitamin D and fat absorption. The finding that parenteral vitamin D increased calcium absorption to normal levels in five patients with primary biliary cirrhosis suggests that deficiency of this vitamin is a major and correctable factor leading to calcium malabsorption in such patients. Precipitation of calcium salts by excess intraluminal fat appears to be a further possible factor reducing calcium absorption in these patients. These findings emphasize the importance of parenteral vitamin D therapy in patients with chronic obstructive biliary diseases. They also suggest that certain patients with chronic parenchymatous liver disease, particularly those who are icteric, may also occasionally require therapy with vitamin D.

Experiments are described that have been designed to measure separately annihilation and reaction cross sections for antiprotons of approximately 450 MeV on oxygen, copper, silver, and lead. A new and more luminous spectrograph has been built for this experiment. The antiproton cross sections a r e compared with total proton cross sections, and are found to be larger by a factor varying from 1.74 for oxygen to 1.39 for silver. Calculations based on the optical model give a reasonable connection between these cross sections and the 6-p and 6-n cross sections. Finally, the information available on antiproton production cross sections is collected. There are indications that a free nucleon is several times as effective as a bound one for producing antiprotons.