PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Conditioning, Operant”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29Linked to original sources
PubMed1995

[Changes in the tissues of a revascularized transplant of small intestine in the dog under different operating conditions].

Histomorphological changes of revascularized autotransplant were studied in 34 dogs in different conditions of the operation. It was established that revascularization is necessary for transplantation. Organ disintegrates without vascular peduncle. Prolonged operative ischemia (up to 3 hrs) of the transplant causes its essential alternative and destructive changes up to the complete disintegration of part of the villi. Autotransplant of the small intestine preserves tissue and cell composition on the neck for a long period (more than a year) and may be used in replacing operations on the esophagus. However, complete organotypic and tissue restoration of the structure does not occur. Villi disappear, crypt epithelium forms structures resembling terminal regions of cardial glands, simple intestinal epithelium is replaced with the stratified one.

Animals↗
PubMed2005

Laminar air flow provides high air quality in the operating field even during real operating conditions, but personal protection seems to be necessary in operations with tissue combustion.

We measured bacterial and particle concentrations at the level of operative fields during 105 operation procedures under laminar air flow conditions. Measured concentrations were at least a factor of 20 lower than in comparable rooms without ultra-clean air and laminar air flow. Kind of operation (septic/aseptic), number of participating persons and quantity of talking seem to have less influence on air quality than presumed, single use cover improves the air quality. The number of ultra-fine and small particles was dramatically increased when tissue was coagulated during operation. This may pose health risks to surgeons and nurses, needs risk assessment and decisions about personal protection.

Air Movements↗
PubMed1964

OPERANT CONDITIONING OF GOATS.

A procedure is described for establishing an operant response in goats. The operanda are two lucite panels which can be transilluminated. The goats press the panels with their muzzles and are reinforced with whole oats. All six subjects showed reliable and accurate performance in brightness discrimination, including cessation of responding during time-out periods.

Animals↗
PubMed2001

Stability of attenuated live virus rabies vaccine in baits targeted to wild foxes under operational conditions.

The viability of an attenuated live virus rabies vaccine in a bait targeted to red foxes was examined under various operational conditions in a series of experiments in Ontario. The virus was relatively stable over a 28-day period in the field, losing a mean 0.5, s = 0.2 log10 of virus titer. The micro-environment into which the bait was placed (open cultivated field, grassy meadow, wooded grove, sun or shade) did not make an appreciable difference in the viability of the virus. There was no significant difference (P < or = 0.05) between mean ambient temperatures and the temperature of fluids in blister packs of baits placed in sun or shade. Sixty-three percent of foxes fed baits exposed to sun and shade conditions for 21 days (titer 10(6.2) tissue culture infective doses per 1 mL) developed rabies virus-neutralizing antibodies. Storage of vaccine baits at -30 degrees C prior to bait distribution was important in maintaining virus viability.

Animals↗
PubMed2003

Kinetic studies of rat liver hexokinase D ('glucokinase') in non-co-operative conditions show an ordered mechanism with MgADP as the last product to be released.

The kinetic mechanism of rat liver hexokinase D ('glucokinase') was studied under non-co-operative conditions with 2-deoxyglucose as substrate, chosen to avoid uncertainties derived from the co-operativity observed with the physiological substrate, glucose. The enzyme shows hyperbolic kinetics with respect to both 2-deoxyglucose and MgATP(2-), and the reaction follows a ternary-complex mechanism with K (m)=19.2+/-2.3 mM for 2-deoxyglucose and 0.56+/-0.05 mM for MgATP(2-). Product inhibition by MgADP(-) was mixed with respect to MgATP(2-) and was largely competitive with respect to 2-deoxyglucose, suggesting an ordered mechanism with 2-deoxyglucose as first substrate and MgADP(-) as last product. Dead-end inhibition by N -acetylglucosamine, AMP and the inert complex CrATP [the complex of ATP with chromium in the 3+ oxidation state, i.e. Cr(III)-ATP], studied with respect to both substrates, also supports an ordered mechanism with 2-deoxyglucose as first substrate. AMP appears to bind both to the free enzyme and to the E*dGlc complex. Experiments involving protection against inactivation by 5,5'-dithiobis-(2-nitrobenzoic acid) support the existence of the E*MgADP(-) and E*AMP complexes suggested by the kinetic studies. MgADP(-), AMP, 2-deoxyglucose, glucose and mannose were strong protectors, supporting the existence of binary complexes with the enzyme. Glucose 6-phosphate failed to protect, even at concentrations as high as 100 mM, and MgATP(2-) protected only slightly (12%). The inactivation results support the postulated ordered mechanism with 2-deoxyglucose as first substrate and MgADP(-) as last product. In addition, the straight-line dependence observed when the reciprocal value of the inactivation constant was plotted against the sugar-ligand concentration supports the view that there is just one sugar-binding site in hexokinase D.

Acetylglucosamine↗
PubMedDate not supplied

A comparative pilot-scale study of the performance of conventional activated sludge and membrane bioreactors under limiting operating conditions.

The behavior of the conventional activated-sludge (CAS) process was compared to that of the membrane bioreactor (MBR) process under limiting operating conditions; that is, at a low solids retention time (SRT) and hydraulic residence time (HRT). The SRT was varied from 2 to 7 days, and the HRT ranged from 5 to 18 hours. The comparison was carried out in terms of nitrification and denitrification kinetics and in terms of the carbon and nitrogen removal performance of these processes. The study involved two pilot-scale units: a CAS unit with a 9-m3 aeration tank and a 225-L MBR. Both of these units were installed and run under real process conditions at a wastewater treatment plant in Evry, France. In the case of the MBR process, the specific nitrification rates, rN, and the specific denitrification rates, rDN, increased as SRT was reduced from 6.5 days to 2 days. This trend was reversed and the rN and rDN decreased only when the HRT was reduced to 5 hours. A similar behavior was observed in the case of the CAS process, although rN and rDN increased only when the SRT was reduced to as low as 4 days; below this value, the rates dropped considerably. It seems that the presence of the membrane renders the MBR more robust by preventing the washout of nitrifiers at low SRT and HRT. Besides the structure and size distribution of the MBR, flocs are more favorable to intraparticle mass transfer than those of the CAS process and could explain the higher nitrification kinetics observed with the MBR process. In all cases, the carbon and nitrogen removal performance of the MBR process was better than that of the CAS system.

Biomass↗
PubMed1992

[Effect of injection of enkephalin and bestatin in caudate-putamen on operant conditioning in rats].

Female Wistar rats were trained in a Skinner-box, 30 trials per day in a dark room to establish operant defence conditioning. Training started with a light (15 s), then combined with footshock for further 8 s. When the rats learned to press the key to avoid footshock within 15 s, conditioned response was considered established. After the rats reached a conditioning rate (CR) above 80% for 5 days, cannulae were implanted into caudate-putamen. Two to three days later, Met-enkephalin (MEK) or bestatin (an aminopeptidase inhibitor) was injected bilaterally into caudate-putamen. 30 min, 2 h, 24 h and 48 h after injection, conditioning tests were conducted, with each session consisting of 30 trials. Control experiments were done when 0.9% NaCl (NS) was injected. After injection of NS, CR maintained above 80% in all 4 test sessions. MEK (60 ng/rat) or bestatin (10 micrograms/rat) significantly lowered the CR during the 30 min and 2 h test session. In the latter case, the latency (L) was also prolonged. However both CR and L returned to the control level in the 24 h and 48 h test sessions. Naloxone (2 mg/kg, i.p.) blocked the conditioning-depression effect of bestatin. No significant alteration was seen in locomotor activity after MEK or bestatin injection. The results suggest that enkephalin in caudate-putamen may be involved in the regulation of retrieval of conditioning. Bestatin mimics the effect of MEK on conditioning reflex probably by increasing production of endogenous enkephalin.

Animals↗
PubMed2002

Change in metabolism of PHA accumulation by activated sludge modifying operating conditions.

In the present work, sludge from a stable and efficient phosphorus removal process was used to evaluate the change in the metabolism when the reactor operation was modified from anaerobic/aerobic to aerobic dynamic substrate feeding. The change in operational conditions allowed the population to modify the metabolism of phosphorus and polyhydroxyalkanoates (PHA) accumulation. Under aerobic dynamic feeding, phosphorus accumulation was almost hindered while the amount of PHA accumulation increased significantly. After ten days of operation under dynamic substrate feeding, the reactor operation turned back to anaerobic/aerobic cycles and the metabolism of phosphorus was progressively recovered.

Bacteria, Aerobic↗
PubMedDate not supplied

Aerosolization potential of cyclodextrins--influence of the operating conditions.

The aim of this work is to characterize the aerosols obtained by jet nebulization with cyclodextrin solutions and to study the influence of operating conditions on nebulization efficiency. Two cyclodextrins, an hydroxypropyl cyclodextrin (Kleptose HP) and a polydisperse methyl beta cyclodextrin (Crysmeb), were tested with 14 nebulizers that differ geometrically. We first determined the physicochemical properties of density, viscosity, and surface tension for the cyclodextrin solutions. Nebulization efficiency was evaluated by measuring droplet size, nebulization rate, quantity of solution nebulized, and nebulization time. We studied the influence of the technological parameters of pressure and nebulizer type and the influence of the formulation on performance efficiency. The use of different nebulizers and different pressure conditions results in variable efficiency. Regardless of the type of nebulizer, an increase in pressure decreases droplet size and increases nebulization rate. The influence of the nebulizer design is considerable. The aqueous cyclodextrin solutions studied can generate aerosols in particle size ranges suitable for pulmonary deposition. Large quantities of aerosol can be nebulized in acceptable nebulization times. The cyclodextrin concentration does not modify nebulization efficiency in the range tested.

Aerosols↗
PubMed1984

Percutaneous absorption of alkanoic acids I: A study of operational conditions.

The rate of penetration of propionic and butyric acids through excised porcine skin was determined in vitro in specific apparatus allowing optimal control of operational conditions. In one technique, the rate was followed by continuous pH-stat titration of acid appearing in the perfusate, in another, by periodic monitoring of [14C]propionic acid in the perfusate. With the assumption that Fick's equation applies to the process of penetration, it was found that the permeability coefficient, Kp, increases with increasing mass of neat penetrant applied per unit area to the donor side, increases with increasing concentration of penetrant in n-heptane as vehicle, increases with increasing temperature, Ea = 11.4 kcal/mol, and decreases with decreasing perfusion rate of the acceptor side when this rate is smaller than 60 mL/h.

Animals↗
PubMed2004

Emission characteristics of industrial sludge incineration in different operating conditions.

Sludge incineration is becoming an important disposal method of industrial sludge from the viewpoint of the need to minimize the environmental impact. This work employs a pilot-scale fluidized bed incinerator to investigate the combustion characteristics of petrochemical sludge. Effects of different operating conditions on the performance of sludge incineration and the emission characteristics are investigated. Experimental results showed that operating temperature, excess air ratio, operating time, moisture of sludge, and chloride additives have significant effects on the combustion efficiency and the formation of air pollutants during sludge incineration. Higher operating temperature, excess air ratio, and lower moisture of sludge are beneficial to reduce the formation of hazardous organic pollutants BTEX (benzene, toluene, ethylbenzene, and xylene) and PAHs (polycyclic aromatic hydrocarbons), but increase the emission of fine particulate. An optimal operating time is also determined, at which interval the bottom ash in the fluidized bed incinerator should be drained or recycled to ensure good combustion efficiency.

Air Pollutants↗
PubMed2004

Minimization of sludge production and stable operational condition of a submerged membrane activated sludge process.

Modification of conventional activated sludge process by adding microfiltration type hollow fiber membrane module offers various advantages. The membrane module is immersed directly in the bioreactor to separate the treated water from the sludge and the modified process is called submerged membrane activated sludge process (SMASP). Bench scale SMASP units were operated at constant flux to study the possibility of minimizing the excess sludge production and stable operation at different SRT and BOD loading. The long SRT developed high stabilized MLSS concentration in the bioreactor and decreased the sludge loading rate [kg-BOD/kg-MLSS-d]. In SMASP, very low sludge yield coefficients (0.04-0.09 kg-MLSS/kg-BOD) were obtained at long SRT (500 d) and small BOD loading (< or =0.5 kg/(m3 x d)) as compared to conventional activated sludge process and these coefficients showed considerable minimization in excess activated sludge production. At the same operation conditions, suction pressure was also maintained low (<25 kPa), and then SMASP was operated stably for long time (approximately 200 d).

Biomass↗
PubMed1983

The effects of distributed training on retention of operant conditioning in human infants.

Long-term retention of operant footkicking acquired in the mobile conjugate reinforcement paradigm was assessed as a function of the distribution of training time. In the first study, 3-month-old infants were trained for either one 18-min session or for two 9-min or three 6-min sessions separated by 24-hr intervals. All infants exhibited retention during a test administered immediately after training, but only those trained in a single session continued to perform the conditioned response during cued-recall tests 7 or 14 days later. Infants trained in three sessions showed no evidence of remembering the contingency even after a week. A warm-up decrement, seen in the day-to-day performance of infants in the distributed conditions, was eliminated in the second study by the interpolation of a nonreinforcement period at the outset of daily sessions. This procedure also enhanced long-term retention such that infants trained in three 6-min sessions now remembered the contingency for 14 days and did not differ from infants who had received a single 18-min session. Whether distributed training facilitates or impairs long-term retention appears to depend on the opportunity for infants to acquire a sufficient number (or kind) of effective retrieval cues during original learning.

Conditioning, Operant↗
PubMed2002

Operating conditions for the determination of the biochemical acidogenic potential of wastewater.

The aim of this work was to study the test conditions for the determination of the biochemical acidogenic potential (BAP) of wastewater, which should be useful to predict the performance of enhanced biological phosphorus removal (EBPR). Proposed operating conditions for a simple and reproducible BAP test in 250 ml serum bottles (equipped with black butyl stoppers and magnetic bars) are: use of either frozen or fresh water, no inoculum addition, fermentation carried out in the dark during 15 days, addition of 1 mM bromo-ethane sulfonate (BES) and 2 mM barium chloride (BaCl2), stirring speed strong enough to maintain vortex conditions, no pH control and controlled temperature of 20 degrees C.

Bioreactors↗
PubMed2005

Development and validation of the Dartmouth Operative Conditions Scale.

Studies of pediatric sedation practice have suffered from the lack of an objective scale that would allow for a comparison of the effectiveness and safety of sedation provided by various providers and techniques. We present the Dartmouth Operative Conditions Scale (DOCS), which is designed as a research tool to codify the appropriateness of the procedural conditions provided by various sedation interventions. To begin, human factors methodology was used to develop a model of the pediatric sedation process and to define the criteria for measuring a patient's condition during a procedure (DOCS). To accomplish validation, 70 video clips (30-s duration) were then selected from more than 300 h of procedural video tape for testing/grading purposes. Inter-rater reliability was tested by comparing the score for each video clip among 10 different raters. Intra-rater reliability was evaluated by retesting all of the raters 1 yr after their initial rating. Construct validity was confirmed by analyzing the change in DOCS score relative to the time that sedation intervention was undertaken. Criterion validity was tested by comparing the DOCS to a modified COMFORT score. The DOCS was completed with excellent inter-rater (kappa = 0.84) and intra-rater (kappa = 0.91) agreement by 10 health care providers with various backgrounds during the 1-yr study period. Criterion validity was supported by the close correlation between the DOCS and the modified COMFORT scores for 20 distinct video clips (Spearman correlation coefficient = 0.98; P <0.001). The distribution of DOCS scores 20 min after the anesthetic induction was significantly lower than the scores before initiation of sedation, and scores after emergence were consistently higher than those 20 min after sedation (P <0.001), thus confirming construct validity of the scale. The DOCS is a validated research tool when used with video data for comparing the effectiveness and safety of pediatric sedation service, regardless of technique used for decreasing anxiety or pain during a procedure.

Child↗
PubMed1980

Operant conditioning of fusional convergence ranges using random dot stereograms.

In Experiment 1, four 6- to 10-year-old strabismus patients, who had failed to improve convergence ranges using traditional vision training techniques, were given convergence training using random dot stereograms (RDS). An integral part of the RDS training procedure was the incorporation of an operant conditioning procedure providing for response-contingent positive reinforcement, immediate feedback, and preprogrammed systematic changes in convergence demand during discrimination learning. Findings indicated that operant RDS convergence training produced a significant increase in convergence ranges which transferred readily to vectogram tasks and resulted in a change from exotropia to exophoria for at least one patient. In Experiment 2, it was shown that improved convergence ability was a direct result of exposure to RDS of increasing convergence demand. It was concluded that young, uncooperative, language-deficient, or inattentive patients show improved convergence ranges when such training incorporates proper stimuli and the basic principles of learning and motivation into its training regimen.

Accommodation, Ocular↗
PubMedDate not supplied

Performances of the immunomagnetic separation method for Cryptosporidium in water under various operation conditions.

Immunomagnetic separation (IMS) has been specified as a standard method for the measurement of Cryptosporidium in some countries. In this study, the IMS method was evaluated on the basis of the recovery efficiencies of Cryptosporidium oocysts at various IMS operation conditions. The average recovery for different Cryptosporidium concentrations in deionized water was 82.6 +/- 18.2% (n = 52). No significant change in recovery was observed by altering the debris ratio of the water samples. The efficiency was increased by prolonging the reaction time, and by increasing the amount of immunomagnetic beads. The recoveries of oocysts seeded in an Eppendorf with a small reaction volume were similar to those seeded in glass tubes with 10 times the reaction volume. The recovery efficiency of oocysts was reduced significantly when the reaction buffer was replaced by PBS. In conclusion, this method has good reproducibility and high recovery.

Animals↗