Search

Studies of reactor safety considerations have demonstrated the need for automatic safety circuit action based on the measured rate of power increase in the power level range from 10{sup {minus}2} to 10 {sup 0} times equilibrium power level. Budget and Preliminary Engineering Studies were performed. This document provides the design criteria for detailed design of the proposed Linear Power Rate-Of-Rise Instrumentation facilities and is applicable to any of the eight IPD reactors.

INTRODUCTION After removal of the liver, ammo acids released from tissue proteins cannot be deaminated and therefore accumulate in the plasma. The rate of rise of the plasma amino acids may therefore be considered a rough indication of the net rate of protein breakdown. When adrenalectomized rats are eviscerated, the accumulation of plasma amino acids is depressed (Bondy, 1949; Ingle, Prestrud and Nezamis, 1948). In a previous communication it was claimed that the administration of large amounts of adrenal cortical extract to eviscerated rats with intact adrenals increased the rate of rise of plasma amino acids above control values within 4 hours (Bondy, 1949). Subsequent attempts to duplicate this experiment were unsuccessful. Further experiments were therefore carried out to determine whether adrenal cortical hormones can influence protein breakdown in the liverless animal, and to evaluate some of the factors concerned in the reaction. METHODS Two sets of experiments were carried out.

In a previous study 2 a method was described for determining diphenylhydantoin (5,5-diphenylhydantoin; phenytoin; Dilantin) concentrations in the serum when the drug was given in therapeutic amounts. With this method were determined the rate of rise of diphenylhydantoin in the serum after oral and after intravenous administration, the hourly and daily fluctuations, the ratio of dosage to serum level, and the rate of fall of serum diphenylhydantoin after withdrawal of the drug. In the study presented in this report the correlation is described between the serum level of diphenylhydantoin and the anticonvulsant effect of the drug, the incidence of paroxysmal abnormalities in the electroencephalogram, and the occurrence of toxic side-effects. Patients and Methods Patients. —1. Twelve patients, 19 to 58 years of age—six men and six women, hospitalized in the neuromedical, neurosurgical, or psychiatric department of the University Hospital. They had not taken diphenylhydantoin before admission to the hospital and

The rate of rise of blood pressure in DCA-treated rats is accelerated by the concomitant administration of Pitressin tannate in amounts close to the antidiuretic range. This indicates that DCA ordinarily causes compensatory inhibition of the neurohypophysis. The fall in plasma Na which is a characteristic extrarenal effect of Pitressin can be elicited with amounts close to the antidiuretic range in the DCA- or aldosterone-pretreated rat. This accords with the view that the mineralocortex and neurohypophysis are reciprocally linked because both act in the same net direction on ionic equilibrium across the cell membrane.

A new technique is described for the instantaneous determination of myocardial force-velocity relationships. The method employs electronic differentiation of the logarithm of intraventricular pressure, which yields a continuous on-line record of (dP/dt)P -1 (the ratio of the rate of rise of ventricular pressure [dP/dt] to the simultaneous ventricular pressure [P]). A further technique is described for the automatic projection of force-velocity vector loops, displaying (dP/dt)P -1 on the ordinate against ventricular pressure on the abscissa in a beat-to-beat fashion. An excellent correlation ( r =0.982) was demonstrated between (dP/dt)P -1 determined by conventional methods and that derived electronically by use of the logarithmic amplifier circuit. Experimental studies are described which document the responsiveness of (dP/dt)P -1 determined by the present method to interventions known to affect myocardial contractility. An increase in (dP/dt)P -1 was observed following infusions of CaCl 2 , norepinephrine, and glucagon, and a decrease following pentobarbital. Insofar as (dP/dt)P -1 is a valid index of myocardial contractility, the present method permits on-line, beat-to-beat evaluation of changes in ventricular function under a variety of circumstances.

The infrared fluorescence risetime of the ν1,ν4 C–H stretching modes of CH3F has been measured in CH3F‐rare‐gas mixtures after pumping of the ν3 C–F stretching modes with a Q‐switched CO2 laser. The pressure‐dependent rate of rise was found to be 122 ± 25 msec−1 · torr−1 in pure CH3F. The effect of rare gases on this rate process was also studied and found to be consistent with a vibration‐vibration filling mechanism for ν1,ν4 involving a small amount of energy transfer (≤ 75 cm−1) into the translational/rotational degrees of freedom.

Publisher Summary This chapter describes the developments in image tube high-speed framing cameras. In the development of high-speed cameras for the investigation of fast-moving phenomena, the demand for increased time resolution is usually met, in the first instance, by recourse to streak photography. The Imacon is normally synchronized to the event by the application of a trigger pulse that starts the sinusoidal oscillation from its peak level. This maintains the camera shuttering in the closed condition until the arrival of the trigger pulse, but introduces a delay, of one-half of the interval between frames, between the receipt of the trigger pulse and the first frame. The system obtains the necessary beam deflections without the generation of a staircase waveform as such. The rate of rise of the linear part of the saw-tooth waveform is adjusted to be identical to the rate of fall of the linear ramp, so that, the two waveforms, when added, give a staircase, the plateaux of which are formed by the cancellation of the rise of one waveform by the fall of the other.

The purpose of this document is to present the latest results of a continuing instrumentation study being conducted by Research and Engineering. In a previous report results of 1-and 6-node calculations, for percentage- and fixed temperature-trip instrumentation were presented. These results were used to obtain a general understanding of the problem and to assess the value of using a multinodal approach. Calculations to determine the amount of protection provided by linear rate and period instrumentation were not performed at that time. Thus, the results of this previous report are limited in that they cover only a part of the possible nuclear safety instrumentation. The previous results indicated that the multinodal approach should be used in analyzing high level and intermediate instrumentation. The results presented in this report were obtained from an 11-node model covering percentage- and fixed-temperature-trip instrumentation, and also linear temperature rate-of-rise and linear power rate-of-rise. Other specialized cases were also investigated. In particular, data were obtained to provide: Eleven-node results for the old reactors; Results for the K reactors comparable to those previously obtained for the old reactors, and results using parameters chosen for the high speed scanner project; Linear power-rate-of-rise at the high levels. Comparison between 6-more » and 3.1-node models; The number of zone temperature indications required for good protection; and Safety parameters for the xenon-override enriched core. This report also includes a section on data used in the analysis and equations for calculating data when it was not available experimentally. It should be emphasized here that before taking data from the curves given in this report, the authors should be consulted to be sure that the results are applicable.« less

THE CONCRETE SETTING TIME CONTROL THAT CAN BE USED BY SET-CONTROLLING ADMIXTURES IS DESCRIBED. STUDIES WERE CONDUCTED ON SUCH PROJECTS AS THE GENTILLY NUCLEAR CENTER, GENTILLY, QUEBEC; THE INTERNATIONAL NICKEL STACK, SUDBURY, ONTARIO; THE HUSKY TOWER, CALGARY, ALBERTA; AND NUMEROUS CEMENT, WOOD CHIP AND FED SILOS IN THE UNITED STATES AND CANADA. THE CONCRETE SETTING TIME IS CORRELATED TO SLIPPING TIME AND RATE OF RISE OF THE SLIPFORM, WITH GUIDES TO ADMIXTURE TYPE AND DOSAGE, MIX PROPORTIONS, AND SUCH SUGGESTED PRACTICES.

Receptor potentials of retinular cells in the eye of the crayfish, Procambarus clarki, were studied with the aid of microelectrodes. Recordings were obtained with the eye excised using intracellular leads or with the eye in situ, using an extracellular approach. The V-logI relationship was observed as well as a somewhat more linear relationship between stimulus intensity and rate of rise. It was shown that a close approximation of the V-logI relationship can be predicted on the assumption that increases in light intensity result in a proportional increase in the number of discrete membrane resistive changes. The effect of light adaptation is to shift the empirically determined Fechner curve to a position of lowered sensitivity on the intensity scale. The slope of the curve is relatively unaffected by this shift. Recovery during dark adaptation is accompanied by a shift in the opposite direction. In both cases reductions in sensitivity are accompanied by decreases in the membrane resting potential. If a constant criterion, ΔV, is imposed on the empirical Fechner functions observed during light adaptation, it is possible to determine the relationship between a threshold intensity, ΔI, and the intensity of the adapting light J. It was observed that ΔI increases as I(where 0.50

When the ``stop-gap`` rate-of-rise meter was installed on all 8 reactors by Amendment 1 to CGI-806 it was intended to replace it with a more satisfactory design when possible. Successful completion of the development program now permits installation of equipment of sufficient reliability to be utilized in the safety circuit. This document defines the program necessary to provide power rate-of-rise protection in the safety circuits of B, C, D, DR, F, H and KE Reactors, provides justification for the project., and presents estimates of the cost and schedule required to accomplish the program.

The rate of rise of blood urea nitrogen (BUN) in acute renal failure in man is extremely variable. This has been attributed to varyingly increased rates of urea production in the presence of tissue catabolism due to infection, trauma, or operative intervention. Some degree of metabolic acidosis is an almost invariable accompaniment of acute renal failure and the effects of the acidosis on the rate of rise in BUN have not received attention. This communication reports a study of acute renal failure in the rat, in which it was possible to demonstrate that correction of acidosis per se significantly diminished the rate of rise of the blood urea nitrogen.Materials and Methods. Male Sprague-Dawley rats, weighing 180 to 280 g, were fasted but allowed free access to water for 16 hr prior to surgery. They were then anesthe-sized with pentobarbital (5 mg/100 g ip) and subjected to either bilateral ureteral ligation or sham operation. Bilateral ureteral ligation was carried out through separate dorsal incisions. Sh...

The ventilatory responses of dogs during bilateral carotid artery perfusions with hypercapnic blood were determined to evaluate the effect upon ventilation of reaching an increment above control of 30.4 mm Hg Pco2 at different rates. A ramp change resulted in a prompt increase in ventilation to the level sustained during the subsequent apparently steady state. A step change resulted in an overshoot of ventilation beyond that anticipated for the ventilatory response if it followed the elevation of mean Pco2. Complete accommodation of ventilation to the ramp stimulus occurred by 5 seconds, when the mean carotid body PCO2 was 49 mm Hg. Following an abrupt decrease of 30.4 mm Hg PCO2, at the end of the perfusions, mean ventilation gradually decreased toward control without an undershoot. The combination of an “excess” ventilation during the ramp function and an “excess” ventilation during recovery suggests that a ramp stimulus at the carotid bodies acts as an effective additional component of the chemical stimulus to ventilation when initiated near eucapnic conditions. Arterial chemoreceptors Ventilatory responses to CO2 Control of breathing Ventilatory transients

SummaryThe effects of x-irradiation (50 kv) on resting- and action-potentials of isolated frog sartorius muscles, of heart-muscle fibres (papillary muscles of cats and Purkinje fibres of calves and sheep) were investigated by the intracellular recording technique. On frog sartorius fibres, radiation doses below 160 kr had no effect on the resting-potential; higher doses led to a dose-dependent decrease of about 1 mv per 160 kr. This effect was independent of the dose-rate in a range from 3 up to 85 kr/min. Shape and amplitude of the action-potential of frog sartorius fibres (stimulus frequency: 0·2/min) were not influenced significantly by irradiation of 15 min duration up to doses of 600 kr.On rhythmically-stimulated (85/min), isolated papillary muscles, irradiation with total doses up to 240 kr had no effect on the resting- and action-potential. Higher doses (345–440 kr) produced a significant fall in the resting-potential, action-potential and rate of rise, as well as a shortening of repolarization-tim...

The effects of the chlorinated hydrocarbon insecticides, DDT and dieldrin, on myelinated nerve fibres of the clawed toad, Xenopus laevis, were studied by recording compound action nerve fibres, and membrane potentials of single nodes of Ranvier. The effect of DDT (5 × 10−4 M) was found to be exclusively on the falling phase of the action potential; either it slowed down the whole falling phase or induced a large negative afterpotential. DDT did not affect threshold voltage, rate of rise and amplitude of the action potential, nor the testing potential. Dieldrin, even in high concentrations (10−3 M), had no appreciable effect on myelinated nerve fibres. DDT caused repetitive firing in sensory fibres only. The number of repetitive action potentials increased gradually with increasing amplitude of the negative afterpotential, while the interval between the action potentials decreased. These results indicate that the DDT-induced negative afterpotential is directly responsible for the repetitive activity. The possible mechanisms by which the negative afterpotential could induce a repetitive response were further investigated. It is suggested that the rate of recovery from sodium inactivation plays a major role in this process.

Responses of the arterial pressure to direct electrical stimulation of spinal tracts at the C5 level were analyzed. Pressor responses with low threshold, high amplitude, and steep rate of rise occurred to stimulation of the dorsolateral zones of the lateral columns. After bilateral destruction of this region the arterial pressure fell to 65. 0±5. 0 mm Hg, responses to stimulation of the pressor zone in the bulbar portion of the vasomotor center disappeared, and responses to stimulation of the peroneal nerve were considerably reduced (to 3. 0± 1.5 mm Hg).

Experiments were designed to study A-V transmission of premature atrial responses by recording electrical activity directly from selected parts of the conducting system. This experimental design permits a more exact interpretation of results than is the case when records are obtained only from the atria and ventricles. Two types of experiments have been conducted in studies of the response of the specialized conducting system of the mammalian heart to premature activation. Records of transmembrane potentials from single fibers of the A-V node and Purkinje system show that premature responses may show a reduced rate of rise and amplitude and thus may be conducted slowly or may decrement completely. Under other conditions, premature responses may show local delay or block because they arise from a local response of considerable duration. Records obtained directly from different parts of the in situ specialized conducting system show that the same phenomena probably occur in the intact, normal heart. These properties of the various fibers of the conducting system, in conjunction with the normal local differences in action potential duration, conduction velocity, and excitability, seem to account quite adequately for the variations which have been noted during A-V propagation of premature responses. On the basis of these results, it seems unnecessary to postulate a dual A-V conducting system in the mammalian heart.

ATTENTION has already been directed to the appreciable rise in the atmospheric radiocarbon activity following the testing of nuclear weapons1–4. On the basis of data obtained up till 1958, Broecker and Walton1 estimated a rise in the atmospheric radiocarbon concentration in the northern hemisphere of 5 per cent per annum, though Munnich and Vogel2 had arrived at a rate of rise of 3.2 per cent per annum. Measurements made in the summer of 1959, however, indicate a general level of activity greatly in excess of what might have been expected from either of these estimations.

The dependence of the effects of stimulation on the rate of rise of the electric current was known to the very first investigators who studied the laws governing the action of an electric current on excitable tissues (Du Bois Reymond, 1848; Pfluger, 1859; Fick, 1863; Engelman, 1870; Werigo, 1888). It was also established that with a decrease in the rate of rise of the stimuli below a certain limit no excitation whatever takes place.

A report is given of an extended trial of a simple modification of the Malloy and Evelyn method for the assay of bilirubin in neonatal jaundice. From a study of the results obtained it is concluded (a) that it is necessary to assay “direct” as well as total bilirubin in all jaundiced newborn babies, (b) that in haemolytic disease of the newborn, the exact rate of rise of “indirect” bilirubin concentration is a useful guide in deciding treatment with exchange transfusion.

1. Measurements of contractions, conduction velocity and intracellular potential were made on isolated rabbit atria under four sets of conditions: high bicarbonate/high CO2 (HH), low bicarbonate/low CO2 (LL), high bicarbonate/low CO2 (HL) and low bicarbonate/high CO2 (LH). The ratio high/low was the same for the bicarbonate and CO2 concentrations, so that HH had the same pH as LL. 2. Acid solutions caused a fall of a few mV in the resting potential, but not in the overshoot. They reduced conduction velocity and rate of rise of the action potential. They depressed contractions, but prolonged the tail of the action potential. 3. Alkaline solutions caused the converse changes, but, with the exception of the effect on the duration of the action potential, the relation with pH was markedly alinear, in that a rise in pH had much less effect than an equivalent fall. 4. Statistical tests were devised to decide whether the observed changes were associated primarily with pH, PCO2 or bicarbonate. By far the strongest association was with external pH. Changes in PCO2, per se, had no significant effect.

Considerable controversy exists regarding the site(s) of origin of so-called junctional rhythms. However, experimental and clinical evidence indicates that a more precise identification of the origin of these rhythms is now possible. Microelectrode recordings from the atrioventricular (A-V) junction have clearly demonstrated that all three zones of the A-V node (upper nodal [AN], midnodal [N], and lower nodal [NH] regions) exhibit action potentials which are functionally different from those recorded in contiguous atrial and His bundle cells. In addition, the amplitude and rate of rise of A-V nodal action potentials are markedly depressed by acetylcholine, a relative sensitivity not shared by atrial and His bundle cells. Cells of the AN and NH regions of the A-V node do show pacemaker activity as do His bundle cells. Experimental studies using His bundle recording techniques indicate significant differences in heart rate between nodal rhythms produced by sinus node isolation or suppression (average: 94 ± 22 beats/min) and His bundle rhythms caused by A-V nodal destruction (average: 39 ± 9 beats/min). Nontoxic doses of ouabain significantly reduced the average A-V nodal rate to 55 beats/min whereas the same dose regimen did not change the average rate of His bundle rhythms. Several clinical studies have claimed that the absence of "A-V nodal" potentials during so-called middle and lower A-V nodal rhythms indicate a site of origin in the His bundle and not the A-V node. However, the nondescript, sometimes spurious nature of A-V nodal recordings severely limits this approach to differentiation of junctional rhythms. Recent clinical studies using His bundle recordings showed that patients with complete heart block and narrow QRS complexes could be clearly divided into two groups. In one group the heart rates ranged from 45-60 beats/min and invariably increased significantly following atropine administration (A-V nodal pacemakers). In the other group heart rates ranged from 35-45 beats/min and there was no significant response to atropine (His bundle pacemakers). Intra-His bundle block could be documented in several patients in the latter group, confirming the His bundle location of the ventricular pacemaker. In conclusion, evidence gained from experimental in vivo and in vitro animal studies and from clinical investigations clearly suggests the existence of at least two pacemakers in the A-V junction. The two A-V junctional pacemakers are distinctly different in both heart rate and chronotropic response to cholinergic or cholinergic-blocking agents.

The objective of this study is to describe the mechanism of production of the first heart sound (S 1 ). The temporal relation between the major components of S 1 and (1) cessation of flow across the mitral valve, (2) closure of the valve, and (3) time of peak rate of rise of left ventricular pressure (peak LV dP/dt), were investigated in open-chest dogs. Phasic flow across the mitral valve was recorded by a supraannular electromagnetic flow probe, and timing of valve closure was determined by synchronized cinefluorogram of the motion of the valve cusps after they were made radio opaque. Closure of the mitral valve did not occur at the crossing point of atrial and ventricular pressures (at the beginning of systole), but 20-40 msec later due to inertia of mitral flow. The first major component of the first sound coincided with two simultaneous events: cessation of mitral flow and closure of the valve. It did not show a fixed temporal relationship to time of peak dP/dt.

Relative biological hazards of blast were studied in two types of communal air-raid shelters during Shots 1 and 8 (Nevada Proving Grounds, 1953). Dogs, restrained within the shelters during detonation, were studied pathologically and clinically for blast injuries. Two anthropometric dummies were test objects for displacement studies utilizing high-speed photography. Physical data included pressure vs time and air-drag determinations. During Shot 1 animals sustained marked blast damages (hemorrhages in lungs and abdominal organs), three dogs were ataxic, and the dummies were rather violently displaced. In Shot 8, however, no significant injuries were found in the animals, and the dummies were minimally displaced. Analysis of the physical data indicated that blast injuries and violent displacements may occur at much lower static overpressures than previously assumed form conventional explosion data. Furthermore, biological damage appeared to be related to the rate of rise of the overpressure and air drag, as well as the maximum overpressure values. These phases of the problem should be defined by further investigation.

Neural spike activity was recorded from 56 single neurons in the olfactory bulb of the unanesthetized, curarized rat. Odor stimulation was provided by puffs from a squeeze bottle or by a dilution-type olfactometer. Each neuron of the group of 33 which responded to odors possessed a unique set of stimuli to which it responded. The neurons showed ‘generalist’ odor sensitivity rather than strict odor specialization. The classification of odor sensitivity is best described by a matrix which shows the responses to the odorants across units. The units in the matrix can be divided into 3 sets; those which responded only with facilitation, only with inhibition, and those which responded with facilitation to some odors and with inhibition to others. The rate of rise of the facilitory response may be rapid, moderate or slow and and the decline during inhibition either rapid or moderate. The responses to each odorant possessed a unique distribution of rise and fall times. The temporal patterns, seen in multi-unit recordings, were observed at the single unit level. A model for odor quality discrimination is provided by the patterning of responses across units and by the temporal patterning across the responses to a particular odorant.

The rising and falling phases of the active state were analyzed, by means of quick-release technique, during a series of 4 incompletely fused isometric twitches in single semitendinosus muscle fibres of the frog. The analysis was carried out at different sarcomere lengths within the range 1.7–2.8 μ. The rate of rise of the active state was independent of the sarcomere length. A reduction in fibre length was associated with an earlier onset of the decay of the active state leading to a decrease in duration of the activity at the shorter length. The duration of the active state at 1.9 μ sarcomere spacing was 69 (range: 51–40) per cent of the duration existing at 2.6 μ sarcomere length as determined in 7 different fibres. Movement (active shortening) per se, apart from the change in sarcomere length, affected the kinetics of the active state. An interval of free shortening interposed during an isometric contraction reduced the fibre's capacity to produce tension for the rest of the contraction period without changing the total duration of the mechanical activity substantially. The movement produced a relatively small effect as long as the active state was maximum; the depressant effect became greater and greater, however, the later the movement occurred during the decay phase of the active state. The nature of the length and movement dependence of the active state is discussed in the light of the calcium-activator mechanism of the excitation-contraction coupling.

The electrophysiological properties of the innervated extensor and soleus muscles are in most aspects similar. In low [Na]o, however, the rate of rise and the amplitude of the action potential were lower in the soleus than in the extensor muscle. The ACh sensitivity in the innervated extensor muscle is limited to the end-plate region, while in the soleus the sensitivity extends beyond the end-plate towards the tendon. Denervation brought a marked change in membrane properties. The electrical time constant of the membrane increased in both muscles almost threefold, and the calculated transverse resistance of unit are of the membrane in the extensor from 372 Σ cm2 to 759 Σ cm2, while in the soleus the values were 393 Σ cm2 to 458 Σ cm2. Denervation increased the threshold for action potential generation and reduced significantly the rate of rise and the amplitude of the spike. These changes were more apparent in the soleus. It is suggested that the decrease in excitability may reflect the lengthening of the time constant and possibly a reduction in the number of membrane sites connected with the passive ionic transport. The ACh sensitivity of denervated muscles covered the entire membrane surface and was similar in both muscles.

This is an open access article distributed under the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

1. Intracellular recordings in adult rat hippocampal slices were used to identify the ionic conductances underlying active spike after-depolarization (ADP) and intrinsic burst firing in the somata of CA1 pyramidal cells (PCs). To test the 'Ca2+ hypothesis', Ca2+ currents were suppressed by replacing the Ca2+ in the saline with either Mn2+ or Mg2+. Alternatively, the inorganic Ca2+ channel blockers Cd2+ (0.5 mM) or Ni2+ (2 mM) were added to the saline. To test the 'Na+ hypothesis', Na+ currents were blocked with tetrodotoxin (TTX; 0.5 microM). 2. The suppression of Ca2+ currents blocked the fast after-hyperpolarization (AHP) generated by the fast Ca(2+)-gated K+ current Ic, while enhancing the amplitude and duration of active spike ADPS. 3. Evoked and spontaneous burst firing was preserved undiminished following Ca2+ current suppression, while the propensity to fire bursts increased in many cases. The postburst medium AHP (generated primarily by the muscarine-sensitive voltage-gated K+ current, IM) was not affected by this treatment, which blocked the slow AHP (generated by the slow Ca(2+)-gated K+ current, IAHP). 4. TTX strongly suppressed active ADPs and intrinsic bursts before substantially reducing the threshold, rate of rise and amplitude of solitary spikes. 5. In Ca(2+)-free saline, caesium-filled PCs generated large, plateau ADPs following an initial burst of fast spikes. Application of TTX suppressed these ADPs before solitary fast spikes appeared to be reduced. 6. Injection of brief, just subthreshold depolarizing current pulses into bursters evoked slow depolarizing potentials lasting up to 50 ms. These persisted after suppression of Ca2+ currents and were entirely blocked by TTX. 7. We conclude that active spike ADPs and intrinsic bursts in the somata of adult CA1 PCs are generated by a low voltage-gated, persistent Na+ current. Burst termination is mediated by voltage-gated K+ currents activated during the burst (most likely IM), rather than by the Ca(2+)-gated K+ currents Ic and IAHP. The latter currents downregulate the innate tendency of CA1 PCs to burst (Ic) and limit the rate of spontaneous burst firing (IAHP).

We present observations of X-rays from laboratory sparks created in the air at atmospheric pressure by applying an impulse voltage with long (250 µs) rise-time. X-ray production in 35 and 46 cm gaps for three different electrode configurations was studied. The results demonstrate, for the first time, the production of X-rays in gaps subjected to switching impulses. The low rate of rise of the voltage in switching impulses does not significantly reduce the production of X-rays. Additionally, the timing of the X-ray occurrence suggests the possibility that the mechanism of X-ray production by sparks is related to the collision of streamers of opposite polarity.

Chlorimipramine (CMI, 1 x 10(-5)M to 7 X 10(-5)M) decreased the amplitude, overshoot and rate of rise of ventricular action potentials and abolished the Ca-mediated action potentials elicited in guinea-pig papillary muscles. These results indicates that CMI inhibits the rise in sodium and calcium conductances during the cardiac action potential.

IN the past few years, interest in recent climatic changes has been growing. Especially in moderate and high latitudes of the northern hemisphere, climatic variations for several decades have been studied. The most striking phenomenon is the rise in temperature, especially that of winter temperatures, up to about 19401. Petterssen1 showed that this climatic change in moderate and high northern latitudes is connected with a variation of circulation. A similar rise in temperature, although much less marked, has occurred in certain equatorial regions2; further, it was found that about the year 1921, or at any rate between 1920 and 1939, the rate of rise of temperature increased rather suddenly.

The dependence of the critical current on its rate of rise is measured for a Nb--25% Zr wire simple in zero applied magnetic field. The critical current density was found to vary from 3.9 to 3.4 x 105 amp/cm2 between 20 and 100,000 amp/sec, respectively.

An algorithm has been developed for the purpose of voiceless stop/fricative distinction in word‐initial position using three measures of the waveform: zero crossings, energy, and derivative of the energy over time (termed rate of rise, ROR). The ROR is used as the primary classifier while energy and zero crossings are used to discard spurious, irrelevant peaks. Peaks in ROR are considered in order of magnitude for relevance to the stop/fricative distinction. The resulting algorithm was treated on 720 CVC tokens (four male speakers, four female speakers, three stops and an affricate [P,T,K,CH], five fricatives [S,SH,F,TH,H], and ten vowel contexts [IY,IH,EH,AE,AA,AH,AO,UH,UW,ER]). Data from two male and two female speakers (360 tokens) were used as a training set, and the remaining data (360 tokens) were used as a test set. The overall success rate was 96.8%. [Work supported by AFOSR.]

To the Editor.— Another drug, phenazopyridine hydrochloride (Pyridium), has been reported now by Feinfeld et al (240:2661,1978) to cause acute renal failure when taken in excess by otherwise healthy young persons. In reading their report, however, I was struck by the discrepancy between the rate of rise of creatinine and BUN levels in their patient. Between the second and third day of hospitalization, the creatinine clearance rose from 2.0 mg/dL to 10.3 mg/dL, while the BUN level rose from 19 mg/dL to 52 mg/dL. In the absence of severe rhabdomyolysis or end-stage liver disease, these BUN-creatinine ratios are extremely uncommon. Generally the creatinine clearance will rise 1 to 2 mg/dL/day during acute renal failure in the absence of rhabdomyolysis. Thus, both the ratios of BUN to creatinine and the absolute rate of rise of creatinine clearance remain unexplained, since the patient had neither hepatic failure nor rhabdomyolysis by virtue of

Routine initiation of phototherapy (PT) within a few hours of birth in VLBW infants has been suggested as a means of modifying the severity and duration of hyperbilirubinemia (HB). The purpose of this study was to determine whether early PT alters the course of HB in VLBW infants. 16 preterm infants, (BW 878 ± 56 g; EGA 27.6 ± 0.4 weeks - mean ± SEM) were randomly assigned to receive PT either within 8 h of birth (E) or after BR reached 5 mg/dl (L). Irradiance at 450 nm was controlled at 12uw/cm2/nm with a Healthdyne Cavitron PT unit. BR values were measured B.I.D., and specimens for configurational (ZE) and structural (LUM) photoisomers were obtained once each day for analysis by HPLC. Age and BR at the onset of PT, peak BR, age at peak, rate of rise of BR, and total duration of PT were compared for both treatment groups. A significant rise in both ZE and LUM (p

This study assessed two recently developed techniques to assess the circumvaginal musculature (CVM), the CVM Rating Scale and the pressure sensitive intravaginal balloon device (IVBD), and correlated results of the two methods. Thirty women volunteers, aged 20 to 42, were studied. CVM Rating Scale total scores and IVBD maximal contraction variables were measured for resting pressure, rate of rise, maximal pressure, rate of return, and time that a submaximal contraction could be sustained (endurance contraction). Age, parity, self-reported orgasm, self-reported Kegel exercises, and self-reported physical exercise were separately correlated with CVM Rating Scale total scores and IVBD maximal pressure results. A positive significant correlation was found between the CVM Rating Scale total scores and the IVBD maximal contraction results for the variables rate of rise, r = .50, p less than .01, maximum pressure, r = .82, p less than .01, and rate of return, r = .44, p less than .01. Self-reported orgasm had a positive significant correlation to the CVM Rating Scale total scores, rho = .34, p less than .05, and to the IVBD maximal pressure results, r = .52, p less than .01. A positive correlation was found between self-reported physical exercise and the CVM Rating Scale total scores, rho = .31, p less than .05. IBVD maximal pressure results were negatively correlated with age, r = -.34, p less than .05, and parity, r = -.34, p less than .05.

The effects of four dietary levels of hexachlorobenzene (HCB) on the accumulation and disappearance of subcutaneous fat residues of HCB were examined in steers. The rate of rise of HCB in the fat increased with dose rate, a level of 98.5 mg kg -1 being reached after ten weeks in steers fed 21 6 mg day -1. Animals fed 36 and 6 mg day -1 recorded average levels of 16.25 and 3.1 mg kg -1 respectively. The residues decreased exponentially; the average half life was 10.5 weeks. Animals maintained on starvation rations for a period of four weeks displayed a reduced rate of elimination of HCB residues from their fat than for animals fed normally. In an experiment with milking cows dosed with four levels of dietary HCB, the uptake of HCB in the butter fat was approximately linear, reaching levels of 0.36, 4.37 and 16.7 mg kg -1 for cows dosed with 1, 6 and 36 mg day -1 respectively. The degradation curves were exponential ; the half life ranged from 4 to 8 weeks with a mean of 6.4.

The rate of rise of the alveolar:inspired halothane concentration (F delta/F1) ratio was measured in dogs breathing spontaneously. These rates were measured at inspired concentrations of 0.3, 1.5, and 4 percent. Initially, FON (FA/F1) ratio was measured in dogs breathing spontaneously. These rates were measured at inspired concentrations of 0.3, 1.5, and 4 percent. Initially FA/F1 rose at similar rates for all 3 concentrations, but a 4 percent, the plateau attained was lower as a result of respiratory depression. In a 2nd group of dogs, FA/FI was measured for inspired concentrations of 0.3, 1.5, 4, and 6 percent during controlled ventilation. FA/FI rose at similar rates at the lower 2 concentrations but at progressively more rapid rates at inspired concentrations of 4 and 6 percent, presumably as a result of circulatory depression.