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Showing papers by "University of California, Irvine published in 1976"


Journal ArticleDOI
TL;DR: The consecutive ones test for the consecutive ones property in matrices and for graph planarity is extended to a test for interval graphs using a recently discovered fast recognition algorithm for chordal graphs.

1,622 citations


Journal ArticleDOI
TL;DR: The time-Petri net (TPN) appears to be a suitable model for the study of practical recoverable processes and several practical communication protocols are formally designed and analyzed using this new model.
Abstract: A study is presented which permits the formal analysis and synthesis of recoverable computer communication protocols. This study is based on a formal representation of processes by a model of computation, the Petri nets (PN's). The PN model is generalized to include a representation of the possible failures, and then, the concept of "recoverability" is formally defined. A set of necessary and sufficient conditions which a process must satisfy in order to be recoverable is derived. In the PN model, the processes that satisfy these conditions are shown to have some practical limitations. A new model, the time-Petri net (TPN), is introduced to remove these limitations. This new model allows the introduction of constraints in the execution times of its part. As shown in this paper, the TPN appears to be a suitable model for the study of practical recoverable processes. Several practical communication protocols are formally designed and analyzed using this new model, and some interesting properties of these protocols are formally derived.

917 citations



Journal ArticleDOI
10 Sep 1976-Science
TL;DR: The model is described, which can explain regulative behavior in cockroach legs, the imaginal disks of Drosophila, and regenerating and developing amphibian limbs, and suggests that it may have general applicability to epimorphic fields.
Abstract: We have described a formal model for pattern regulation in epimorphic fields in which positional information is specified in terms of polar coordinates in two dimensions. We propose that cells within epimorphic fields behave according to two simple rules, the shortest intercalation rule and the complete circle rule, for both of which there is direct experimental evidence. It is possible to understand a large number of different behaviors of epimorphic fields as a straight-forward consequence of these two rules, and the model therefore provides a context in which to view many of the results of experimental embryology. Although we have confined our discussion to cockroach legs, the imaginal disks of Drosophila, and regenerating and developing amphibian limbs, the fact that the model can explain regulative behavior in such evolutionarily diverse animals suggests that it may have general applicability to epimorphic fields. The predictions which the model makes should make it possible to assess its applicability to other developing systems, and to investigate the cellular mechanisms involved.

844 citations


Journal ArticleDOI
TL;DR: This paper investigated the relationship between organizational commitment and turnover among a sample of managerial trainees in a large merchandising company and found that early leavers tended to show an early decline and later leavers a later decline.

645 citations


Journal ArticleDOI
02 Jul 1976-Science
TL;DR: A framework of operational mechanisms that begin to clarify some aspects of the recognized influence of species diversity on herbivory are discussed, including diversionary and delaying tactics to the adaptation-counteradaptation view of plant-herbivore coevolution.
Abstract: Optimal plant defense should incorporate any mechanisms that influence the feeding behavior of potential pests. From a diverse collection of examples suggesting that the defense of a plant may be improved in the company of specific neighbors, we discuss a framework of operational mechanisms that begin to clarify some aspects of the recognized influence of species diversity on herbivory. Neighbors serve as insectary plants for herbivore predators and parasites, and influence herbivore feeding behavior by repelling, masking, attracting, and decoying. Insectary plants lower the numerical response of herbivores by increasing the efficiency of their predators and parasites. Repellent plants primarily lower functional response by causing the predator to fail to locate or reject its normal prey. Attractant-decoy plants dilute herbivore impact by drawing off herbivores, either increasing or decreasing their numerical and functional response (or either). The concept of gene conservation guilds adds diversionary and delaying tactics to the adaptation-counteradaptation view of plant-herbivore coevolution. The useful life of a given gene for resistance may best be extended by mechanisms that disrupt genetic tracking (specialization) by herbivores. Some plants may remain inedible not because their chemistry or morphology represents an evolutionary impasse, but because they live in an environment that provides acceptable options of variable quality. Feeding environments that provide little or no choice promote specialization by forcing physiological adaptation. Conversely, the evolutionary momentum of specializing herbivores may be lowered by enhancing their susceptibility, either by selection against virulent individuals, or by decreasing the exposure frequency of susceptible genotypes. The latter mechanism of conserving susceptible individuals takes advantage of herbivore behavioral sensitivity to variable plant quality. Direct selection against virulent genotypes requires temporal cycling of the herbivore population between resistant and nonresistant hosts. Both events may occur within defense guilds that provide acceptable feeding options of similar but distinctive quality.

571 citations



Journal ArticleDOI
TL;DR: Far-field auditory brainstem responses were recorded in patients in whom the distribution of pathology was defined at autopsy or at operation and it is concluded that Wave I reflects activity of VIII nerve, Waves II and III reflect activity of cochlear nucleus, trapezoid body, and superior olive and Waves IV and V reflectActivity of lateral lemniscus and inferior colliculus.

515 citations


Journal ArticleDOI
30 Apr 1976-Science
TL;DR: Neuronal activity in dorsal hippocampus was recorded in rabbits during classical conditioning of nictitating membrane response, with tone as conditioned stimulus and corneal air puff as unconditioned stimulus as mentioned in this paper.
Abstract: Neuronal activity in dorsal hippocampus was recorded in rabbits-during classical conditioning of nictitating membrane response, with tone as conditioned stimulus and corneal air puff as unconditioned stimulus. Unit activity in hippocampus rapidly forms a temporal neuronal "model" of the behavioral response early in training. This hippocampal response does not develop in control animals given unpaired stimuli.

494 citations


Journal Article
TL;DR: In this paper, the authors used prolonged extracorporeal membrane oxygenation (ECMO) in the treatment of 13 moribund infants (including 9 neonates), with 4 survivors (3 neonates).
Abstract: We have used prolonged extracorporeal membrane oxygenation (ECMO) in the treatment of 13 moribund infants (including 9 neonates), with 4 survivors (3 neonates). Successfully treated cases include post-operative cardiac failure, infant respiratory distress syndrome, massive meconium aspiration, and persistent fetal circulation. All cases have been managed with veno-arterial bypass at flow rates of 80-100 cc/Kg/min. Carotid cannulation for arterial access and careful control of heparin anticoagulation based on whole blood activated clotting time are among the techniques which have contributed to this success. Progressive pulmonary or cardiac failure has been the major problem in older infants, intracranial bleeding is the major problem in neonates. Both of these problems could be minimized by instituting ECMO earlier in the clinical course, but this awaits development of reliable early predictors of mortality.

487 citations


Journal ArticleDOI
TL;DR: The ligaments of the wrist were studied by dissecting ten fixed and seven fresh frozen wrists and suggest that certain patients with a generalized ligamentous laxity and weakness will develop a pathological disruption of the volar ligaments with trauma.
Abstract: The ligaments of the wrist were studied by dissecting ten fixed and seven fresh frozen wrists. In three other specimens multiple cross-sections were prepared. These studies show that the wrist ligaments can be classified into two groups: extrinsic and intrinsic. In the extrinsic group, the deep volar radiocarpal ligaments are three strong and very important structures connecting the radius to the capitate, the radius to the lunate, and, in a deeper layer, the radius to both the scaphoid and the lunate. A ligamentous deficiency was noted frequently between the capitate and the lunate. There also are very strong volar connections between the radius and the medial or ulnar carpus. These studies suggest that certain patients with a generalized ligamentous laxity and weakness will develop a pathological disruption of the volar ligaments with trauma. These torn volar ligaments should be repaired or reconstructed, for repair of only the dorsal ligaments seldom will provide good stability to such wrists.

Journal ArticleDOI
TL;DR: The extent and time course of degeneration is described and the nature of the reinnervation processes is described; degenerating entorhinal terminals behaved as a population which disappeared randomly at a rate dependent on the fraction of terminals present at any time.

Journal ArticleDOI
TL;DR: The authors' data indicate that granule cells retain a capacity even into adulthood to manufacture, position and assemble postsynaptic components of a synapse and, in concert with reactive afferents, form normal-appearing synapses.

Journal ArticleDOI
TL;DR: It is concluded from this study that an excitatory amino acid, either aspartic or glutamic, may function as the transmitter in the corticostriate projection.

Journal ArticleDOI
04 Mar 1976-Nature
TL;DR: Fusion between malignant and normal human cells results in the suppression of malignancy as measured by tumour formation.
Abstract: Fusion between malignant and normal human cells results in the suppression of malignancy as measured by tumour formation. Malignant-malignant hybrids retain their malignant character. The human cell system has advantages for the study of the control of malignancy.

Journal ArticleDOI
TL;DR: In this paper, the notion of a monotone map is generalized to that of a pseudomonotone mapping and it is shown that a differentiable, pseudoconvex function is characterized by the pseudomonotonicity of its gradient.
Abstract: The notion of a monotone map is generalized to that of a pseudomonotone map. It is shown that a differentiable, pseudoconvex function is characterized by the pseudomonotonicity of its gradient. Several existence theorems are established for a given complementarity problem over a certain cone where the underlying map is either monotone or pseudomonotone under the assumption that the complementarity problem has a feasible or strictly feasible point.

Journal ArticleDOI
08 Apr 1976-Nature
TL;DR: These phenomena must involve profound alterations of synaptic biochemistry, but the requisite biochemical studies cannot be performed until the transmitters used by these inputs are known.
Abstract: IN the rat hippocampal formation, the major excitatory inputs possess a remarkable degree of physiological and morphological plasticity. Long lasting potentiation has been reported1–3 and, at least in the dentate gyrus, the synaptic loss consequent on removal of one afferent is compensated by formation of additional synapses by intact afferents4,5. These phenomena must involve profound alterations of synaptic biochemistry, but the requisite biochemical studies cannot be performed until the transmitters used by these inputs are known.

Journal ArticleDOI
05 Nov 1976-Science
TL;DR: A model predicting that in nectarivorous birds territorial behavior will occur above a lower threshold of nectar productivity in a foraging area and disappear above an upper threshold and decline of efficiency of territorial exclusiveness is predicted.
Abstract: A model is proposed predicting that in nectarivorous birds territorial behavior will occur above a lower threshold of nectar productivity in a foraging area and disappear above an upper threshold. These thresholds are determined by the daily costs of living of territorial and of nonterritorial individuals and by the pressure of competing birds for the resource. Decline of efficiency of territorial exclusiveness is predicted as productivity increases from the lower to the upper threshold. Hawaiian honeycreepers (Vestiaria coccinea) supported the model.

Journal ArticleDOI
01 Sep 1976-Brain
TL;DR: Auditory brain-stem responses were measured by far-field recording techniques in 27 patients fulfilling the criteria of brain death and showed a decrease in amplitude and a prolongation of latency of the later components until finally Wave I was alone.
Abstract: Auditory brain-stem responses were measured by far-field recording techniques in 27 patients fulfilling the criteria of brain death. The responses were either absent or consisted of the presence of just the initial component (Wave I). Wave I, when present, was of normal amplitude but prolonged in latency. Four patients were followed over several days from a state of coma with evidence of preserved brain-stem and cerebral functions to a clinical state compatible with brain death. Auditory brain-stem responses were initially intact and then showed a decrease in amplitude and a prolongation of latency of the later components until finally Wave I was alone. Auditory brain-stem responses are an objective measure of one of the sensory pathways traversing the brain-stem and can be used to evaluate the functional states of the brain-stem in patients in whom the question of brain death has been raised.

Journal ArticleDOI
TL;DR: The relationship of the findings on local anesthetic-induced changes in cellular cytoskeletal systems is discussed in relation to previous proposals on plasma membrane organization and control of cell surface receptor topography and mobility.
Abstract: Tertiary amine local anesthetics (dibucaine, tetracaine, procaine) reversibly affect the morphology of untransformed BALB/3T3 cells and the organization of membrane-associated cytoskeletal elements. In the presence of these drugs cells contract and become rounded in shape with the appearance of numerous surface "blebs." Electron microscope examination of anesthetic-treated cells revealed significant reductions in plasma membrane-associated microtubules and microfilaments and/or their plasma membrane attachment. The relationship of the findings on local anesthetic-induced changes in cellular cytoskeletal systems is discussed in relation to previous proposals on plasma membrane organization and control of cell surface receptor topography and mobility.

Journal ArticleDOI
TL;DR: Serum levels of other "acute-phase proteins" were found to increase in response to surgical procedures, but subsequent to the increase in C-reactive protein, and these other proteins offer no additional information in monitoring the postoperative acutephase response.
Abstract: Serial determinations of serum C-reactive protein are helpful in the detection and monitoring of postoperative complications associated with inflammation and/or tissue necrosis. The serum C-reactive protein level begins to increase within sex hours after operation, peaks on the second day, and by the third postoperative day begins to decrease toward the preoperative level. In cases with surgical complications involving inflammation, serum C-reactive protein levels remain elevated and do not show a decline on the third postoperative day. Serum levels of other "acute-phase proteins," such as alpha-1 acid glycoprotein, ceruloplasmin, alpha-1 antitrypsin, and haptoglobin, were found to increase in response to surgical procedures, but subsequent to the increase in C-reactive protein. These other proteins offer no additional information in monitoring the postoperative acutephase response,

Journal ArticleDOI
TL;DR: The general view that ACTH may modulate memory storage processing of recent information is supported, and the possibility that other post-trial treatments which facilitate or impair memory processes may act via hormonal mechanisms is suggested.

Journal ArticleDOI
TL;DR: The response of the astroglial population of the dentate gyrus molecular layer to removal of that region's primary afferent was investigated using Cajal's gold sublimate method, leading to the conclusion that these cells migrate into denervated dendritic areas from neighboring, nondeafferented zones.

Journal ArticleDOI
TL;DR: Results are consistent with the view that hormonal consequences of an experience, particularly epinephrine, norepinephrine and ACTH release, may normally have a modulatory influence on memory processes in untreated animals and it is therefore possible that other posttrial treatments which enhance or impair later retention performance may act through hormonal mechanisms.

Journal ArticleDOI
TL;DR: The spatial dependence of the ring‐current magnetic anisotropy of nucleic acid bases is presented in a series of graphs in cylindrical coordinates and distance effects are found to influence considerably the predicted chemical shifts of nuclei acid protons, particularly in RNA duplexes.
Abstract: The spatial dependence of the ring-current magnetic anisotropy of nucleic acid bases is presented in a series of graphs in cylindrical coordinates. The curves may be used to calculate the ring-current shift at a point in a cylinder of radius 10A extending 8 A above and below each ring of the base. These distance effects are found to influence considerably the predicted chemical shifts of nucleic acid protons, particularly in RNA duplexes. The contribution of polarization (electric field) effects and the diamagnetic anisotropy of individual atoms (local Δχ) are briefly discussed.

Journal ArticleDOI
TL;DR: Increases in the anatomical extent of the crossed projection as a consequence of unilateral entorhinal lesions are reflected electrophysiologically and the population spikes are quite prominent in the reinnervated dentate gyrus, indicating a large increase in the effective synaptic drive of the proliferated crossed projections.

Journal ArticleDOI
26 Feb 1976-Nature
TL;DR: It is shown for the first time that the developmental capacity of imaginal disk cells from Drosophila can be altered by appropriate grafting operations and undergo pattern regulation when parts are removed.
Abstract: IN this paper we show for the first time that the developmental capacity of imaginal disk cells from Drosophila can be altered by appropriate grafting operations. The appendages of amphibians and immature arthropods, and the imaginal disks of holometabolous insects, are capable of undergoing pattern regulation when parts are removed. (Pattern regulation is used here to describe the alteration of cell fates in response to an abnormal situation in a developing system; we include under this term both regeneration and duplication.) Regulation then occurs during growth of the tissue by cell division, a process termed epimorphosis1. A characteristic feature of epimorphic regulation which has recently been recognised, is the different regulative responses shown by complementary pieces. For example when an imaginal disk of Drosophila is bisected and allowed to grow for some time, one of the two fragments usually regenerates the missing parts, while the other undergoes duplication of the presumptive pattern already present2. Similarly, whereas the stump of an amputated amphibian or cockroach limb can regenerate distally, the amputated distal part, if kept alive by grafting to a host animal, can also undergo pattern regulation by forming the distal pattern elements, thereby duplicating itself3–6.


Journal ArticleDOI
08 Apr 1976-Nature
TL;DR: The finding that adenosine derivatives are released from dendrites and particularly axon terminals points to the neurones as a major source for the released nucleotides2.
Abstract: ADENOSINE is postulated to function in the brain as an inter-cellularly active neurohumoral substance. This has been suggested by in vitro studies showing that adenosine can be released from brain tissue by electrical stimulation at quantities which are sufficient to increase the formation of cyclic AMP1. The finding that adenosine derivatives are released from dendrites and particularly axon terminals points to the neurones as a major source for the released nucleotides2. Thus, nucleotides may function as ‘secondary’ or ‘additional’ neuronal transmitters mediating long lasting effects of a neurone on the metabolism and function of its target cells. Further evaluation of these hypotheses will require demonstrations that endogenous adenosine or its derivatives are actually released by synaptic connections in the intact brain and that this process is influenced by activation of these connections. We have carried out experiments in which tritiated adenosine was transported from cell bodies into a population of terminals, and in which the amount of radioactive materials taken up by the target cells of these terminals was measured in the presence and absence of synaptic stimulation. Stimulation was found to increase the release of 3H-adenosine derivatives from central axon terminals to their postsynaptic neurones.

Journal ArticleDOI
TL;DR: In this paper, the relationship between satisfaction with the work itself (SWI) and job scope (JS) was examined for the study's total sample and for subsamples formed by grouping individuals on the basis of their scores on each of six workrelated values measures and a Protestant ethic (PE) index involving these measures.