Showing papers by "University of Iowa published in 1973"
TL;DR: In this paper, an inventory model is considered for deteriorating items with a variable rate of deterioration, where deterioration means decay, damage or spoilage such that the item cannot be used for its original purpose.
Abstract: An inventory model is considered for deteriorating items with a variable rate of deterioration, where deterioration means decay, damage or spoilage such that the item cannot be used for its original purpose. Specifically, the Weibull distribution is used to represent the distribution of the time to deterioration. The EOQ formula is derived under conditions of constant demand, instantaneous delivery and no shortages, and it is shown that the results can be related to previously developed simpler models. A computer program is developed to provide the numerical solution and a numerical example is used to show the solution form and verify that the solution gives minimum total cost per unit time. An economic lot size model has been developed for situation in which the deterioration follows a Weibull distribution. The theoretical derivation was shown to reduce to the previous model found by Ghare and Schrader when the deterioration was exponential in nature and to a non deteriorating EOQ model when det...
705 citations
TL;DR: For the knee, mathematical analyses for the sagittal plane were performed on data obtained from roentgenograms and a load cell incorporated in a specially constructed force table to find the axis of rotation for the knee displaced 3·2 cm through a 90° range.
510 citations
TL;DR: The results of these experiments strongly suggest that the inferior olive is able to generate the activation of motoneurons and that such influence can only take place through theactivation of the cerebellar nuclei.
Abstract: Intracellular recording from Purkinje cells in cat cerebellar cortex demonstrated an 8–10/sec burst activity following intravenous administration of harmaline (10 mg/kg), a drug known to produce tremor at the same frequency. The burst activation of Purkinje cells was generated by large all-or-none depolarizations similar to climbing fiber (CF) excitatory postsynaptic potentials (EPSPs). Polarization of the cell membrane through the recording electrode (via a Wheatstone bridge) revealed that the all-or-none depolarization had an equilibrium potential and time course identical to the electrically evoked CF-EPSP, demonstrating directly that tremor is associated with specific activation of the CF afferent system. Interspike frequency histograms of the burst responses of Purkinje cells show that the rhythmic CF activity may continue for several hours with approximately 10% frequency scatter, the actual frequency depending on the level of anesthesia. Simultaneous extracellular recordings from Purkinje cells near the midline vermis indicated that CFs projecting to this area fire in a synchronous manner, while simultaneous recording from three Purkinje cells at different lateralities from the midline showed that the rhythmic activity is reduced in the lateral vermis and may be absent in the cerebellar hemispheres. Intra- and extracellular recordings from cerebellar nuclear cells (fastigial) disclosed a bursting type of activation following harmaline; a similar type of activity could be recorded in the reticular formation neurons and at inferior olive level. At spinal cord level, harmaline induced a repetitive and rhythmic activation of motoneurons which was not modified by dorsal root section. Cooling of the cerebellar cortex produced a definite desynchronization of the rhythmic motoneuronal firing. However, the basic 10/sec firing of the spinal cord motoneurons could still be observed. Following lesion of the inferior peduncles which interrupted the olivo-cerebellar pathway, the rhythmic activation of Purkinje cells, nuclear cells, vestibular and reticular cells and motoneurons disappeared. However, the rhythmic activity was maintained at inferior olivary level. It is suggested that harmaline acts directly on the inferior olive since in animals with low decerebration, cerebellectomy and spinal transection, rhythmic activity of the inferior olive could still be observed. The results of these experiments strongly suggest that the inferior olive is able to generate the activation of motoneurons and that such influence can only take place through the activation of the cerebellar nuclei. Possible functions of the inferior olive as a generator of fast muscular transients are discussed.
438 citations
TL;DR: This paper found that a teacher's expectations about a child's behavior strongly influence his actual behavior, and that the teachers' expectations did in- deed have an enormous impact on students' performance, and they found that the child's attractiveness was significantly associated with how intelligent the child was, how interested in education his parents were, how far he was likely to progress in school and how popular he would be with his peers.
Abstract: Rosenthal and Jacobson found that a teacher's expectations about a child's behavior strongly influence his actual behavior. Generally, teachers form their first impressions of children, and thus develop their expectations for them, from two sources of information-the children's school record and their physical appearance. In this experiment, teachers were given objective information, presumably about a child's scholastic and social potential, ac- companied by a photograph of an attractive or an unattractive boy or girl. It was found that the child's attractiveness was significantly associated with the teacher's expectations about how intelligent the child was, how interested in education his parents were, how far he was likely to progress in school, and how popular he would be with his peers. ROSENTHAL AND JACOBSON (1968) argue that a teacher's expecta- tions as to how a child will behave have an enormous impact on how the child does behave. To prove this assertion, they con- ducted an experiment in a public elementary school. They gave students a standard IQ test, telling the teachers that this test mea- sured "intellectual blooming." The researchers chose 20 per cent of the children at random, and informed their teachers that the test had identified them as very special children who would "bloom" (show a marked intellectual "spurt") within the next year. One year after this deception, the same IQ test was again administered to all children. The results revealed -that the teachers' expectations did in- deed have an enormous impact on students' performance. The supposed "bloomers" showed far more improvement in IQ than did the other youngsters; gains were especially pronounced for the * This research was financed in part by NIMH Grant MH 1661, NSF Grant GS
389 citations
267 citations
TL;DR: The data would indicate the need for a critical study of the causes of intracranial hemorrhages, and re-evaluation of the true relationship of systemic hypertension to such strokes, and the widespread dogma that hypertension is the outstanding cause of nontraumatic brain hemorrhage no longer seems warranted.
Abstract: A detailed clinicopathological study of the causes and locations of massive nontraumatic brain hemorrhage in 144 patients is reported. A cause of the hemorrhage, such as an aneurysm, angioma, arteritis, neoplasm or a blood dyscrasia (leukemia, hemophilia), was proved in two-thirds (95) of these patients. Twelve normotensive patients had no cause found to explain their hemorrhage. Systemic hypertension, generally mild, defined as a pre-ictal pressure of > 140/90 or by excessive heart weight, was present in 58 of the 144 patients. Twenty-one of these 58 hypertensive patients had a clear discernible cause for their brain hemorrhage (i.e., leukemia, metastatic carcinoma, angioma, aneurysm), whereas no satisfactory morphological cause could be found in only 37. Thus, in only about one-fourth of our patients could any serious claim be made that hypertension was the cause of the hemorrhage. Our data would indicate the need for a critical study of the causes of intracranial hemorrhages, and re-evaluation of the t...
231 citations
TL;DR: The most prominent features of the convection electric fields are reversals located at high magnetic latitudes, with generally antisunward convection poleward and sunward convections equatorward of the electric field reversal location as mentioned in this paper.
Abstract: Simultaneous electric field and plasma observations with the low-altitude polar-orbiting satellite Injun 5 have provided a comprehensive survey of convection electric fields and their association with magnetospheric plasma phenomena. The most prominent features of the convection electric fields are reversals located at high magnetic latitudes, with generally antisunward convection poleward and sunward convection equatorward of the electric field reversal location. The electric field reversal is interpreted as the boundary between open and closed magnetic field lines. During local day the electric field reversal is observed to coincide with the equatorward boundary of the polar cusp. The plasma flow in the dayside polar cusp region is dominantly E-W, away from the stagnation point, the convection velocities typically being about 1 km/sec. At local evening, 'inverted V' electron precipitation bands are observed near or at the position of the electric field reversal. In the local late-evening sector the electric field reversal becomes less distinct, and often no single well-defined electric field reversal can be identified. In all cases the inverted V electron precipitation events are closely associated with large, typically greater than 30 mV/m, irregular electric field fluctuations with time scales of a few seconds or less.
220 citations
TL;DR: In this article, an electromagnetic noise band was observed in the outer magnetosphere by the Imp 6 spacecraft at frequencies from about 5 to 20 kHz, and it was concluded that this noise must be trapped in the low density region between the plasmapause and magnetopause boundaries.
Abstract: An electromagnetic noise band is frequently observed in the outer magnetosphere by the Imp 6 spacecraft at frequencies from about 5 to 20 kHz. This noise band generally extends throughout the region from near the plasmapause boundary to near the magnetopause boundary. The noise typically has a broadband field strength of about 5 microvolts/meter. The noise band often has a sharp lower cutoff frequency at about 5 to 10 kHz, and this cutoff has been identified as the local electron plasma frequency. Since the plasma frequency in the plasmasphere and solar wind is usually above 20 kHz, it is concluded that this noise must be trapped in the low-density region between the plasmapause and magnetopause boundaries. The noise bands often contain a harmonic frequency structure which suggests that the radiation is associated with harmonics of the electron cyclotron frequency.
199 citations
TL;DR: Electrophoretic analysis of Escherichia coli clones reveals a prominent mobility class (frequency over 0.70) and 2 to 11 distinct mobility classes at lower frequencies, which argues against the importance of neutral mutations in allozymic variation.
Abstract: At each of five loci in 829 Escherichia coli clones from 156 samples from diverse natural sources, electrophoretic analysis reveals a prominent mobility class (frequency over 0.70) and 2 to 11 distinct mobility classes at lower frequencies. The frequency distribution of the classes argues against the importance of neutral mutations in allozymic variation. Heterosis is not the universal cause of genic polymorphism.
199 citations
TL;DR: P4 was found to be a satellite virus, depending on a helper genome for the completion of its lytic life cycle, and it is proposed that P4 produces a transactivating factor that triggers the expression of the helper genes that have to fulfill the late functions needed by P4.
164 citations
TL;DR: Comparative recognition accuracies for physiognomic and verbal stimuli were compared when these stimuli were tachistoscopically presented to the left and right visual fields of normal dextral subjects, indicating a majority of the subjects demonstrated a right visual field superiority for the recognition of trigrams.
TL;DR: In this method, the moments are first estimated in order to solve a set of differential equations for the velocities and displacements involved during gait so that as the variations between the calculated and the measured displacements decreases the desired solution for the moments is approached.
TL;DR: A system whereby pure cultures of endothelial cells derived from umbilical veins can be subcultured for at least five serial passages and many facets of endothelium function and interaction can be evaluated with the use of this new adaptive system of isolation and culture.
Abstract: Investigative studies dealing with the properties and functions of endothelial cells have been hampered because there has been little or no success in the isolation, growth, and passage of individual cells in large numbers. We have developed a system whereby pure cultures of endothelial cells derived from umbilical veins can be subcultured for at least five serial passages. Many facets of endothelial function and interaction can be evaluated with the use of this new adaptive system of isolation and culture.
TL;DR: Morphological and electrophysiological studies of the agranular cerebellar cortex of ferret after infection with panleukopenia virus have led to the following conclusions: Purkinje cells can show normal excitability following antidromic invasion, and may be activated by the mossy and climbing fiber afferent systems.
Abstract: Morphological and electrophysiological studies of the agranular cerebellar cortex of ferret after infection with panleukopenia virus have led to the following conclusions:
A.
At light microscopic level this agranular cerebellar cortex is shown to be totally disorganized when compared to its normal lamination.
B.
From an ultrastructural point of view, Purkinje cells are present throughout the thickness of the cerebellar cortex, demonstrating dendritic branches studded with unwed spines.
C.
Purkinje cells receive four different types of inputs-climbing fibers, mossy fibers, stellate cell terminals, and Purkinje cell axon collateral terminals. The mossy fiber contacts which are generally not present in mammals are made in some cases to elongated, “dolichoderic” spines.
D.
Stellate, basket, and Golgi cell interneurons are present, and receive inputs from mossy and climbing fiber terminals, and probably from axon collaterals of Purkinje cells. The mossy fiber input to these neurons represents a true reorganization of the cerebellar circuit, since it has never been observed in any other vertebrate.
E.
Stellate and basket cells terminate in contact with dendrites and somata from Purkinje cells, while the Golgi cell terminals seem to be restricted to somata and dendrites of other Golgi cells.
F.
Electrophysiologically, Purkinje cells can show normal excitability following antidromic invasion, and may be activated by the mossy and climbing fiber afferent systems. Intra-and extracellular recording from Purkinje cells demonstrates that the mossy fiber afferent system activates Purkinje cells with a latency of approximately 1 msec and its excitatory action is graded with relation to the amplitude of the white matter stimulation. Following an initial excitation, this input generates a longlasting inhibition (50 msec), which is attributed to mossy and climbing fiber activation of inhibitory interneurons.
G.
Climbing fiber activation generates the typical all-or-none burst response in Purkinje cells extracellularly. Intracellularly, large unitary EPSPs characteristic of this form of activation may be recorded with a latency of 1.5 to 3 msec. This large unitary EPSP seems to behave in the usual one-to-one relation (one climbing fiber to one Purkinje cell).
H.
Double climbing fiber activation reveals that a conditioning white matter stimulation produces a total inhibition of a climbing fiber burst at 15 msec interval, which indicates a rather strong inhibitory action on Purkinje cells following this form of activation.
I.
Climbing fiber activation is followed in most cases by a so-called climbing fiber reflex, suggesting that the inferior olive in this agranular condition is functioning in a normal manner.
J.
Finally, some of the neurobiological implications of these findings are considered in the discussion.
TL;DR: Morphine (5, 10, and 20 mg/kg, subcutaneously) both suppressed and elevated lateral hypothalamic self-stimulation response output, indicating the facilitatory action is not due simply to a rebound phenomenon.
Abstract: Morphine (5, 10, and 20 mg/kg, subcutaneously) both suppressed and elevated lateral hypothalamic self-stimulation response output. The duration of the depressant effect and the temporal appearance of the excitatory influence were dose dependent. With repeated daily injection tolerance developed to the suppressive effect while the facilitatory effect appeared ealier and tended to be enhanced. Thus the facilitatory action is not due simply to a rebound phenomenon. Finally, no correlation between the effects of morphine on self-stimulation behavior and on wheel-running activity was observed.
TL;DR: Experimental patients reported that they slept better and experienced less anxiety the morning of surgery; they recalled more facts about their experiences on the day of surgery, and their recollections less often involved fearful and unpleasant images.
Abstract: In a study of the influence of psychological preparation for surgery, the evening before their surgery 25 experimental patients participated in a small group session at which they discussed their concerns and fears and received information about what to expect and how they could aid in their recuperation. They were contrasted with a randomly selected matched control group of 25 patients who underwent similar procedures, but received only the routine care. Verbal, interactional, and physiological variables were measured. The research hypothesis, that the extra preparation would increase patient participation, decrease tension and anxiety, and lead to a more rapid postoperative recovery, was supported. Experimental patients reported that they slept better and experienced less anxiety the morning of surgery; they recalled more facts about their experiences on the day of surgery, and their recollections less often involved fearful and unpleasant images; they experienced less operative urinary retention, required less unesthesia; they required less pain medication, returned more rapidly to oral intake, and were discharged sooner.
TL;DR: The purpose of the present work was to determine whether changes in FFA concentration within this range would influence drug transport by plasma albumin, and to suggest that in the usual physiological concentrations, FFA binding is confined almost to long-chain FFA.
Abstract: Plasma albumin is the transport vehicle for many metabolites and drugs that are relatively insoluble in aqueous media. These substances are not linked covalently to albumin; they are bound physically, usually through a combination of nonpolar and electrostatic interactions. One of the most important metabolites transported by plasma albumin is free fatty acid (FFA) , the form in which fat is released from the adipose tissue storage depots.' The plasma FFA concentration is quite variable and is rapidly responsive to changes in nutritional status, physical activity, and environmental stimuli.2--' However, under ordinary conditions, the molar ratio of FFA to albumin in the plasma usually is in the range of 0.5 to 2.0, and it rarely exceeds 3.0.'~\" The purpose of the present work was to determine whether changes in FFA concentration within this range would influence drug transport by plasma albumin. The prevailing viewpoint is that physiological changes in the plasma FFA concentration have little or no influence on drug binding. This interpretation originated with Goodman's classical study of FFA binding to human plasma albumin.9 Goodman demonstrated that albumin contained three classes of binding sites for large organic anions. The association constants for FFA binding to the primary sites, ranging from 1.3 x lo-' M-1 for linoleate to 1.1 X lo8 M-l for oleate, were much larger than those reported for other organic ligands. Moreover, the presence of 1.8 pequiv of FFA did not influence the binding of methyl orange to albumin.!' The Scatchard model for methyl orange binding contained only two classes of sites, and the association constants were similar to those of the secondary and tertiary FFA binding sites. Based upon these observations, Goodman suggested that the second and third classes of albumin binding sites are shared by many organic ligands, whereas the primary sites, because of greater structural specificity, interact only with long-chain FFA. This general concept has been applied widely to drug transport; namely, that in the usual physiological concentrations. FFA binding is confined almost
TL;DR: Synchronous excitation of an ensemble of elements in the nervous system generates field potentials in and around the ensemble that can provide information about neuronal function.
Abstract: Synchronous excitation of an ensemble of elements in the nervous system generates field potentials in and around the ensemble. Experimental analysis of these potentials can provide information about neuronal function.
TL;DR: Application of cell-free culture filtrates of Vibrio cholerae or its purified enterotoxin to ligatured loops of rabbit ileum or to human ileal mucosa is associated with stimulation of mucosal adenyl cyclase activity, increase of intracellular cyclic AMP and exudation of water and electrolytes into the intestinal lumen.
Abstract: THE diarrhoea associated with natural cholera infection is thought to be caused by an enterotoxin produced by the cholera bacillus. Application of cell-free culture filtrates of Vibrio cholerae or its purified enterotoxin to ligatured loops of rabbit ileum or to human ileal mucosa is associated with stimulation of mucosal adenyl cyclase activity, increase of intracellular cyclic AMP and exudation of water and electrolytes into the intestinal lumen1–3. The mechanisms involved are, however, unknown.
TL;DR: In this article, the fluctuation spectra of eight recently discovered pulsars are presented along with a description of the drifting-subpulse phenomenon in several objects with quasiperiodic responses in their fluctuation spectrum.
Abstract: Pulsar observations at meter wavelengths have been analyzed to investigate pulse-to-pulse variations and to identify regions of the pulse profile which display distinct statistical properties. Fluctuation spectra of eight recently discovered pulsars are presented along with a description of the drifting-subpulse phenomenon in several objects with quasiperiodic responses in their fluctuation spectra. A quantitative analysis of the drifting-subpulse phenomenon in PSR 0031-07 and PSR 0809+74 is given which emphasizes the broad-band nature of the phenomenon. A summary of the memory exhibited by pulsars with time scales of about 50 periods is given.
TL;DR: Failure of interventricular septum motion to revert to normal following surgical correction in patients with atrial septal defect suggests that additional factors are involved in the persistence of this abnormal motion.
Abstract: Abnormal systolic motion of the interventricular septum has previously been noted using echocardiography in patients with atrial septal defect and has been ascribed to right ventricular volume overload. To evaluate the mechanism responsible for this abnormality, right ventricular volume overload was created in open-chest dogs by pumping blood from the left atrium to the right atrium. In seven of eight dogs changes in interventricular septum motion were produced acutely at shunt flow as low as 500 cc/min. When the shunt was decreased or stopped, interventricular septum motion returned to normal. Shunts producing left ventricular volume overload (aorta to left atrium and right atrium to left atrium) caused no change in interventricular septum motion. Clinical observations showed that six of seven patients with partial anomalous pulmonary venous connection and no atrial septal defect displayed abnormal interventricular septum motion on echocardiography. Twenty-one patients undergoing surgery for atrial septa...
TL;DR: It is concluded that the marked changes in PWM following posterior infarction were due to echocardiographic detection of dyskinesis in the infarcted area rather than to generalized changes in ventricular function.
Abstract: Posterior wall velocities have been advanced as a useful technic for the assessment of left ventricular function. To evaluate the echocardiographic effects of regional myocardial infarction on posterior wall motion (PWM), measurements were obtained in 22 open-chest dogs. Coronary artery ligation produced infarction of the apex in 11 dogs (group I) and the posterior wall in 11 dogs (group II). Echoes were thus received from noninfarcted myocardium in group I and from infarcted myocardium in group II. Postinfarct recordings in group I showed no significant changes in posterior wall velocities or excursion. In contrast, group II showed striking changes in the contour of PWM with a large initial posterior displacement (aneurysmal bulging) during isometric contraction, followed by a slow anterior movement during ventricular ejection and then a rapid anterior recoil motion during isometric relaxation. Mean posterior wall velocity fell from 31 ± se 3 mm/sec preinfarct to 13 ± 4 postinfarct (P < 0.01); from 33 ± ...
TL;DR: This article investigated the effect of contextual and trial stimulus lighting conditions on key-peck autoshaping in pigeons and found that white illumination of a response key before food presentation readily produced keypecking in a brightly lit chamber but failed to do so in a chamber without house illumination.
Abstract: Three experiments investigated the effect of contextual and trial stimulus lighting conditions on keypeck autoshaping in pigeons. White illumination of a response key before food presentation readily produced keypecking in a brightly lit chamber but failed to do so in a chamber without house illumination (Experiments I and III). Keypecking in a darkened cubicle progressively increased and the facilitatory effect of a houselight decreased as the keylight stimulus was varied from a color change (Experiment II) to a feature change (Experiment III). These findings support a “cue localization” hypothesis of autoshaping. according to which reinforcement signals select specific behaviors for expression and direct these behaviors toward the source of stimulation. This account was extended to superstitious and operant conditioning situations.
TL;DR: A deterministic epidemic model is modified to allow vaccination and a definition of preventing or controlling an epidemic is given and the use of the dynamic programming technique to construct the optimal vaccination program is illustrated.
Abstract: A deterministic epidemic model is modified to allow vaccination and a definition of preventing or controlling an epidemic is given. The question of finding an optimal vaccination strategy (a least cost vaccination program for a given cost functional) to prevent an epidemic is posed. The use of the dynamic programming technique to construct the optimal vaccination program is illustrated. Optimal vaccination schedules are given which were computed for some specific theoretical epidemics.
TL;DR: Bilateral cervical vagotomy did not change closure tension or abolish relaxation with swallowing in the lower esophageal sphincter of the opossum, studied by manometry in vivo.
TL;DR: This finding, in conjunction with the well established right visual field superiority for the perception of verbal material, strongly supports the hypothesis that asymmetry in human perceptual performance reflects hemispheric asymmetry of function rather than peripheral factors.