Convulsions as a condition complicating operations under general anaesthesia.
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Anesthesia↗
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Results for “Conditioning, Operant”
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Learned changes of brain states alter cognitive processing in humans.
Humans can learn to intentionally control their brain states based on information about their own electrocortical activity. Using an operant conditioning technique, twelve healthy volunteers were trained to shift their slow cortical potentials recorded from left-hemispheric language cortices in the positive versus negative direction. After training, six subjects who achieved reliable control of left-hemispheric brain responses showed substantial modification of word processing. During conditioned negative shifts of cortical potentials (activation condition), responses to words were substantially speeded, whereas lexical decisions were slower during positive shifts of slow cortical potentials (inhibition condition). No comparable difference was seen in trained participants who failed to achieve control over slow cortical potentials. Additional data suggest that the effect was not related to perception, attention, or motor processes. Thus, operant conditioning can produce focal cortical activity dynamics and thereby modify specific higher cortical processes such as access to words. This finding may open new perspectives on neuropsychological rehabilitation based on operant conditioning of brain responses.
Adult↗
Air conditioning hospital operating rooms.
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Air Conditioning↗
Performance modeling and simulation of biochemical process sequences with interacting unit operations.
Many biochemical processes consist of a sequence of operations for which optimal operating conditions (setpoints) have to be determined. If such optimization is performed for each operation separately with respect to objectives defined for each operation individually, overall process performance is likely to be suboptimal. Interactions between unit operations have to be considered, and a unique objective has to be defined for the whole process. This paper shows how a suitable optimization problem can be formulated and solved to obtain the best overall set of operating conditions for a process. A typical enzyme production process has been chosen as an example. In order to arrive at a demonstrative model for the entire sequence of unit operations, it is shown how interaction effects may be accommodated in the models. Optimal operating conditions are then determined subject to a global process objective and are shown to be different from those resulting from optimization of each separate operation. As this strategy may result in an economic benefit, it merits further research into interaction modeling and performance optimization.
Alcohol Dehydrogenase↗
Investigation into the rejuvenation of spent electroless nickel baths by electrodialysis.
Electroless nickel plating generates substantially more waste than other metal-finishing processes due to the inherent limited bath life and the need for regular bath disposal. Electrodialysis can be used to regenerate electroless nickel baths, but poor membrane permselectivity, leading to high losses of valuable bath components, continues to be a weakness of the technology. This research has investigated improving electrodialysis permselectivity for removing contaminants (sodium, orthophosphite, and sulfate) in a spent electroless nickel bath while minimizing the losses of valuable bath ions (nickel, hypophosphite, and organic acids). Ion permselectivity was explored with respect to electrodialysis operating conditions, membrane type, and cell configuration. Excellent permselectivity for sodium over nickel was attained irrespective of operating condition, membrane, or cell configuration. Studies on the effects of four different operating conditions (current density, pH, flow rate, and temperature) on anion permselectivity revealed bath pH and current density to be critical operating parameters. The type of anion exchange membrane used had a crucial effect on selectivity; one membrane (Ionac MA-3475) was identified as having superior selectivity for bath contaminants particularly for sulfate. The improvements in electrodialysis permselectivity established by this research will decrease waste generation within the electroless nickel process and increase resource productivity by minimizing the loss of valuable plating chemicals.
Electroplating↗
In-line interferometer for direction-sensitive displacement measurements by optical feedback detection.
We demonstrate a compact in-line interferometer for direction-sensitive displacement measurement by optical feedback detection with a semiconductor laser (SL) light source. Two reflected beams from a semitransparent reference mirror and a reflecting test object interfere in the SL medium, causing a variation in its output power. The reference mirror is located between the SL output facet and the test object. The performance of the interferometer is investigated numerically and experimentally to determine its optimal operating conditions. We have verified the operating conditions where the behavior of the SL output power profile could indicate accurately the displacement magnitude and direction of the moving test object. The profile behavior is robust against variations in optical feedback and scale of the interferometer configuration.
Journal Article↗
Domestic sewage treatment in a pilot system composed of UASB and SBR reactors.
The results obtained from the operation of a treatment system composed of an anaerobic (up-flow sludge blanket-UASB) reactor followed by an aerobic (sequencing batch-SBR) reactor treating domestic sewage are presented and discussed. The pilot plant was monitored during 6 months, aiming to obtain performance data on organic matter, nitrogen and phosphate removal under different operating conditions. The UASB reactor was operated at a constant hydraulic detention time (0) of 6 h while the SBR performance was monitored in four different duration cycles (24, 12, 6 and 4 h) corresponding to aeration times (AT) of 22, 10, 4 and 2 h, respectively. COD and TSS overall removal efficiencies (Eo) up to 91% and 84%, respectively, were achieved independently on the aeration time applied to the SBR. In respect to nitrification and phosphate removal, AT was found to be a determining operating parameter. TKN removal of approximately 90% was achieved for AT equal to or higher than 10 h; complete nitrification occurred for AT higher than 4 h; significant phosphate removal (72%) occurred only at the AT of 2 h. It was not possible to achieve simultaneous efficient removal of nitrogen and phosphate, under the operating conditions imposed on the treatment system.
Bacteria, Aerobic↗
Particle size distribution to design and operate an APT process for agricultural wastewater reuse.
Total suspended solids is a parameter commonly used to operate and design coagulation-flocculation processes. Nevertheless, their application for an advanced primary treatment (a high performance but low dose demand coagulation processes coupled with a high rate sedimentator, sometimes called enhanced primary treatment) is not the best option to produce an effluent for agricultural irrigation. This paper compares the best operating conditions obtained using the TSS or the PSD (particle size distribution) as parameters to follow the efficiency. The treatment objective was to remove particles >20 microm, in such conditions that the effluent can contain organic matter and nutrients necessary for crops with a reduced number of helminth ova (with sizes between 20 to 80 microm). Using the TSS as parameter, the best coagulation (460 s(-1), 60 s contact time and 300 micromolAl/L) and flocculation (20 s(-1) with 15 min) conditions produced an effluent with 1.2 HO/L. To obtain a similar results but using operating conditions determined with the PSD at a three times lower coagulant dose can be employed (diminishing operating costs and reducing the quantity of sludge produced), and a reduction on energy consumption of around eight times can be reached. Best operating conditions defined using the PSD (160 s(-1), 60 s contact time and 100 micromolAl/L) produced an effluent with <0.4 HO/L.
Agriculture↗
Probable corticospinal tract control of spinal cord plasticity in the rat.
Descending activity from the brain shapes spinal cord reflex function throughout life, yet the mechanisms responsible for this spinal cord plasticity are poorly understood. Operant conditioning of the H-reflex, the electrical analogue of the spinal stretch reflex, is a simple model for investigating these mechanisms. An earlier study in the Sprague-Dawley rat showed that acquisition of an operantly conditioned decrease in the soleus H-reflex is not prevented by mid-thoracic transection of the ipsilateral lateral column (LC), which contains the rubrospinal, reticulospinal, and vestibulospinal tracts, and is prevented by transection of the dorsal column, which contains the main corticospinal tract (CST) and the dorsal column ascending tract (DA). The present study explored the effects of CST or DA transection on acquisition of an H-reflex decrease, and the effects of LC, CST, or DA transection on maintenance of an established decrease. CST transection prior to conditioning prevented acquisition of H-reflex decrease, while DA transection did not do so. CST transection after H-reflex decrease had been acquired led to gradual loss of the decrease over 10 days, and resulted in an H-reflex that was significantly larger than the original, naive H-reflex. In contrast, LC or DA transection after H-reflex decrease had been acquired did not affect maintenance of the decrease. These results, in combination with the earlier study, strongly imply that in the rat the corticospinal tract (CST) is essential for acquisition and maintenance of operantly conditioned decrease in the H-reflex and that other major spinal cord pathways are not essential. This previously unrecognized aspect of CST function gives insight into the processes underlying acquisition and maintenance of motor skills and could lead to novel methods for inducing, guiding, and assessing recovery of function after spinal cord injury.
Animals↗
Expanded bed adsorption as a primary recovery step for the isolation of the insulin precursor MI3 process development and scale up.
Expanded bed adsorption (EBA) was evaluated for the isolation of the human insulin precursor MI3, expressed and secreted by the yeast Saccharomyces cerevisiae. The isoelectric point of the insulin precursor (pH 5.3) makes cation exchange a prime candidate for direct adsorption. In order to find a suitable window of operation for the process the adsorption equilibrium was analysed in a wide range of operating conditions (pH and conductivity) and for three different stationary phases. The same array of operating conditions was examined with regard to stable fluidisation of the adsorbents in S. cerevisiae suspensions. Interactions of the yeast with the fluidised stationary phase were investigated by a pulse response technique and the hydrodynamics of the fluidised bed under process conditions by residence time distribution analysis. The case study demonstrates that by parallel examination of product binding and fluidisation quality a window of operation can be found. Analysis of the binding kinetics by breakthrough experiments and modelling led to the definition of a set of operating conditions, which yield a compromise between optimal use of the equilibrium capacity provided by the adsorbent and high throughput required for an industrial separation. After initial experiments on the bench scale the protocol was transferred successfully to pilot scale demonstrating the design of a reliable operation.
Adsorption↗
A molluscan model system in the search for the engram.
A 3-neuron central pattern generator, whose sufficiency and necessity has been directly demonstrated, mediates aerial respiratory behaviour in the pond snail, Lymnaea stagnalis. This behaviour can be operantly conditioned, and this associative learning is consolidated into long-lasting memory. Depending on the operant conditioning training procedure used the learning can be consolidated into intermediate term (ITM) or long-term memory (LTM). ITM persists for only 2-3 h, whilst LTM persists for days to weeks. LTM is dependent on both altered gene activity and new protein synthesis while ITM is only dependent on new protein synthesis. We have now directly established that one of the 3-CPG neurons, RPeD1, is a site of LTM formation and storage. We did this by ablating the soma of RPeD1 and leaving behind a functional primary neurite capable of mediating the necessary synaptic interactions to drive aerial respiratory behaviour by the 3-neuron CPG. However, following soma ablation the neuronal circuit is only capable of mediating learning and ITM. LTM can no longer be demonstrated. However, if RPeD1's soma is ablated after LTM consolidation memory is still present. Thus the soma is not needed for the retention of LTM. Using a similar strategy it may be possible to block forgetting.
Animals↗
Methodology for predicting the separation of proteins by hydrophobic interaction chromatography and its application to a cell extract.
Hydrophobic interaction chromatography (HIC) is widely used in the downstream processing of proteins. Resolution of HIC is very good, but sometimes not as high as expected. Resolution values could be increased if good operating conditions were selected. In this paper we present a methodology for selecting good operating conditions. First, it is necessary to predict the dimensionless retention time (DRT) of each protein in the mixture. We use a correlation such as DRT = A + Bphi + Cphi2, where phi is the superficial hydrophobicity of the protein, which is calculated considering the hydrophobicity of the superficial amino acids using the Miyazawa-Jernigan scale. Considering that there was little interaction amongst proteins in a mixture at the concentrations investigated (2 g/l of each protein), the behaviour of the proteins in the mixture was considered to be similar to that of the individual proteins. Using simulations it was possible to test different operating conditions for the purification of a target protein from a mixture of proteins and it was possible to select ideal conditions. The methodology developed was also tested for the purification of a recombinant protein from a fermentation extract of yeast producing human superoxide dismutase and the results have been satisfactory.
Cell Extracts↗
Selective spinal anesthesia for outpatient laparoscopy. II: epinephrine and spinal cord function.
PURPOSE: To compare two small-dose solutions (with and without epinephrine) for spinal anesthesia during outpatient laparoscopy and to determine spinal cord function with these low-dose solutions. METHOD: Twenty outpatients undergoing gynecological laparoscopy were randomly assigned to receive spinal anesthesia with one of two low dose solutions. Group LS-10 mg lidocaine plus 10 microg sufentanil; Group LSE-10 mg lidocaine plus 10 microg sufentanil plus epinephrine 50 microg. Solutions were diluted to three millilitres with sterile water for injection. A 27-gauge Whitacre needle was inserted at L2-3 or L3-4 in the sitting position. Operating conditions and spinal cord function (spinothalamic, dorsal column and motor) were assessed. RESULTS: Operating conditions were good-excellent in both groups. The incidence of shoulder tip discomfort, pruritus and nausea, and the amount of supplementation with alfentanil and midazolam was not different between groups. Most patients in both groups had preserved dorsal column function and normal motor power on arrival in PACU and were able to satisfy 'walk out' criteria. Recovery of pinprick sensation and discharge times were not different. Mild pruritus (VAS score < or = 5) was present in both groups. CONCLUSION: For short duration laparoscopy, addition of 50 microg epinephrine to a small dose of spinal 10 mg lidocaine with 10 microg sufentanil did not provide additional benefit in terms of intraoperative analgesia or operating conditions. Spinal cord function was preserved with small-dose techniques.
Adult↗
[Gynecologic laparoscopy with or without curare].
OBJECTIVE: To assess physiological changes and operating conditions during general anaesthesia with or without neuromuscular blockade in patients undergoing gynaecologic laparoscopy. STUDY DESIGN: Prospective, randomized, double-blind study. PATIENTS: Fifty non-obese patients, mean age 31 years, randomly allocated into either a group of 25 with curare (AC) or a group of 25 without curare (SC). METHODS: All patients were anaesthetized with propofol (2.5 mg.kg-1), sufentanil (0.4 microgram.kg-1) midazolam (2 mg) and N2O-O2. In addition, those of the AC group were given atracurium 0.25 mg.kg-1 for intubation, followed by additional boluses to maintain twitch height < 10% of the control value. Blood pressure, heart rate, peak airway pressure, end-tidal carbon dioxide pressure were recorded before and during pneumoperitoneum maintained at a pressure of 15 mmHg. Operating conditions were assessed at 10-min intervals, using a four point scale. RESULTS: In both groups, blood pressure and heart rate decreased following induction. The decrease in blood pressure was more important in the SC group at 5 min and before pneumoperitoneum (25 vs 15%); P < 0.05). The time course of PETCO2 and peak airway pressures were similar between groups. Operating conditions were not influenced by the muscle relaxant. CONCLUSIONS: Neuromuscular blockade influences neither most of the clinical haemodynamic and respiratory changes induced by pneumoperitoneum for gynaecologic laparoscopy not the operating conditions.
Adult↗
Minimising biomass/adsorbent interactions in expanded bed adsorption processes: a methodological design approach.
Expanded bed adsorption (EBA) is an integrated technology for the primary recovery of proteins from crude feedstock. Interactions between solid matter in the feed suspension and fluidised adsorbent particles influence bed stability and therefore have a significant impact on protein adsorption in expanded beds. In order to design efficient and reliable EBA processes a strategy is needed, which allows to find operating conditions, where these adverse events do not take place. In this paper a methodological approach is presented, which allows systematic characterisation and minimisation of cell/adsorbent interactions with as little experimental effort as possible. Adsorption of BSA to the anion exchanger Streamline Q XL from a suspension containing S. cerevisiae cells was chosen as a model system with a strong affinity of the biomass towards the stationary phase. Finite bath biomass adsorption experiments were developed as an initial screening method to estimate a potential interference. The adhesiveness of S. cerevisiae to the anion exchanger could be reduced significantly by increasing the conductivity of the feedstock. A biomass pulse response method was used to find optimal operation conditions showing no cell/adsorbent interactions. A good correlation was found between the finite bath test and the pulse experiment for a variety of suspensions (intact yeast cells, E. coli homogenate and hybridoma cells) and adsorbents (Streamline Q XL, DEAE and SP), which allows to predict cell/adsorbent interactions in expanded beds just from finite bath adsorption tests. Under the optimised operating conditions obtained using the prior methods, the stability of the expanded bed was investigated during fluidisation in biomass containing feedstock (up to 15% yeast on wet weight basis) employing residence time distribution analysis and evaluation by an advanced model. Based on these studies threshold values were defined for the individual experiments, which have to be achieved in order to obtain an efficient EBA process. Breakthrough experiments were conducted to characterise the efficiency of BSA adsorption from S. cerevisiae suspensions in EBA mode under varying operating conditions. This allowed to correlate the stability of the expanded bed with its sorption efficiency and therefore could be used to verify the threshold values defined. The approach presented in this work provides a fast and simple way to minimise cell/adsorbent interactions and to define a window of operation for protein purification using EBA.
Adsorption↗
Multi-model statistical process monitoring and diagnosis of a sequencing batch reactor.
Biological processes exhibit different behavior depending on the influent loads, temperature, microorganism activity, and so on. It has been shown that a combination of several models can provide a suitable approach to model such processes. In the present study, we developed a multiple statistical model approach for the monitoring of biological batch processes. The proposed method consists of four main components: (1) multiway principal component analysis (MPCA) to reduce the dimensionality of data and to remove collinearity; (2) multiple models with a posterior probability for modeling different operating regions; (3) local batch monitoring by the T(2)- and Q-statistics of the specific local model; and (4) a new discrimination measure (DM) to identify when the system has shifted to a new operating condition. Under this approach, local monitoring by multiple models divides the entire historical data set into separate regions, which are then modeled separately. Then, these local regions can be supervised separately, leading to more effective batch monitoring. The proposed method is applied to a pilot-scale 80-L sequencing batch reactor (SBR) for biological wastewater treatment. This SBR is characterized by nonstationary, batchwise, and multiple operation modes. The results obtained for the pilot-scale SBR indicate that the proposed method has the ability to model multiple operating conditions, to identify various operating regions, and also to determine whether the biosystem has shifted to a new operating condition. Our findings show that the local monitoring approach can give more reliable and higher resolution monitoring results than the global model.
Biodegradation, Environmental↗
Performances under representative pressure and temperature conditions of the gas chromatography-mass spectrometry space experiment to investigate Titan's atmospheric composition.
In the frame of the calibration of the aerosol collector and pyrolyser, and gas chromatography-mass spectrometry experiments of the Huygens probe arrived at Titan, systematic experimental studies were led to estimate the influence of the operating conditions on the analyses that should have been achieved in the Titan's atmosphere. The primary objective of this study was to estimate the influence of operating conditions variations induced by (i) instrumental modifications made shortly before the probe launch which can have changed the operating pressures; (ii) the change of the probe environmental conditions (pressure, temperature) during its descent in the atmosphere; (iii) a possible deviation of pressure and temperature regulations from their nominal values because of the long journey of the instrument in space, or of other external events. The secondary objective of this work was to create an analytical database that can be used as a reference to treat the chromatograms obtained in situ, and help to identify chromatographically the analyzed species, complementary to mass spectrometry. Beyond the application to a specific instrument, this work was also useful to experimentally estimate the fundamental evolution of the separation as a function of the changes of operating conditions with time. The obtained results show (i) the significant influence of inlet and outlet pressure variation on the time of analysis, but not on the separation power. It thus enables to significantly shorten the analysis duration, and thus to analyze more compounds within the fixed time of analysis of the instrument; (ii) the significant influence of temperature on the retention. In this frame, the enthalpies of exchange between the gas phase and the stationary phase of the species were determined to be used to retrieve the analyzed species in case of deviation of the operating temperature; (iii) that the possible aging of the columns does not have influence on the columns efficiency and separation power; (iv) the analytical capabilities of the gas chromatography-mass spectrometry experiment within operating conditions representative of those encountered in situ. Finally, in spite of possible operating condition changes, it is shown that results coming from the gas chromatograph-mass spectrometer experiment, which are currently under analysis, could bring important information on the Titan's atmosphere and its history.
Atmosphere↗
Perturbation of the activity of a single identified neuron affects long-term memory formation in a molluscan semi-intact preparation.
The aim of this study was to investigate the neural basis of operant conditioning in a semi-intact preparation of the pond snail, Lymnaea stagnalis. Lymnaea learns, via operant conditioning, to reduce its aerial respiratory behaviour in response to an aversive tactile stimulus to its open pneumostome. Here we report the successful conditioning of naïve semi-intact preparations to show ;learning in the dish' and long-term memory that persists for at least 18 h. The neurons that generate this behaviour are readily identifiable and, for the first time, we have recorded from a neuron during a training paradigm that leads to long-term memory formation in the same preparation. Specifically, we recorded from the respiratory neuron Right Pedal Dorsal 1 (RPeD1), which is part of the respiratory central pattern generator and initiates the aerial respiratory behaviour. Previous studies have shown that long-term memory of this behaviour results in reduced RPeD1 activity. In the present study, we demonstrate that preventing RPeD1 impulse activity between training sessions reduces the number of sessions needed to produce long-term memory in our semi-intact preparation.
Animals↗