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PubMedDate not supplied

Behavioral teratology investigation of 1-butanol in rats.

Two concentrations of 1-butanol (3000 and 6000 ppm) were administered by inhalation to separate groups of 15 pregnant Sprague-Dawley rats for 7 hr per day throughout gestation; 18 male rats were similarly exposed for 7 hr per day for 6 weeks, and mated to unexposed females. Litters were culled to 4 female and 4 male pups and fostered to untreated controls. From days 10-90, offspring were tested as follows: a) ascent on a wire mesh screen, b) rotorod, c) open field and photoelectrically-monitored activity, d) running wheel, e) avoidance conditioning, and f) operant conditioning. Additionally, brains from 10 offspring at 21 days of age were dissected into cerebrum, cerebellum, brainstem, and midbrain. Each sample was assayed for protein and the neurotransmitters acetylcholine, dopamine, norepinephrine, serotonin, met-enkephalin, beta-endorphin, and substance P. Overall, there were few behavioral or neurochemical alterations detected in the offspring following maternal or paternal exposure to either 3000 or 6000 ppm 1-butanol. This scarcity of effects is important to risk assessment extrapolations drawn from ethanol. Based on the structural similarity of 1-butanol to ethanol and long-standing observations that toxicity to adult animals generally increases with chain length among the alcohols, significant behavioral and neurochemical deviations were predicted. The scarcity of effects from butanol needs to be accounted for in hypotheses relating toxicity to alcohol chain length and in risk assessment extrapolations from findings with ethanol.

Animals↗
PubMed2003

On-line analysis of the size distribution of fine and ultrafine aerosol particles in flue and stack gas of a municipal waste incineration plant: effects of dynamic process control measures and emission reduction devices.

The size distribution of particles in the waste gas of a municipal waste incineration plant (23 MW) was measured on-line at two sampling points in the flue-gas duct (700 and 300 degrees C) as well as in the stack gas (80 degrees C). The measurements were performed during both stable combustion conditions and transient operating conditions. The particle measurements were carried out by a mobile system consisting of a home-designed sampling system with dilution device and a scanning mobility particle sizer (SMPS) for the particle size range 17-600 nm as well as an aerodynamic particle sizer (APS) for the size range 500 nm-30 microm. The APS and SMPS data were combined using a special method and a home written software tool. The maximum of the particle-size distribution in the flue gas of the incinerator shifts from about 90 nm at the 700 degrees C sampling point to about 140 nm at the 300 degrees C point, showing the particle growth by coagulation processes and condensation of inorganic and organic gaseous species with decreasing temperature. This finding is consistent with the measured concentration profiles of gaseous organic chemical species in the flue gas. While at flue-gas temperatures of 600-800 degrees C a rich pattern of polycyclic aromatic hydrocarbon species (PAH) is observable, the PAH concentrations are considerably reduced further downstream of the flue-gas channel, where the temperature drops below 500 degrees C. Condensation and reactive bonding of gaseous chemicals onto particulate matter is, among other reasons, responsible for the depletion of gas-phase species. Process control measures, such as firing the backup burners or cleaning of the grate with pressurized air, can cause dynamic changes of the particle-size distribution. Furthermore the flue-gas cleaning measures have great impact onto both the particle concentration and the size distribution. For this reason the impact of one particular emission reduction device, the wet electrostatic dust precipitator (wet-ESP), is evaluated. The wet-ESP reduces considerably the particle concentration over the whole size range. Behind the flue-gas processing units a broad maximum in the particle-size distribution occurs at about 70 nm, but no pronounced particle-size distribution could be observed. The particle concentration level atthis maximum is about 3 magnitudes lower than in the raw flue gas. However, intermittent periods lasting for several minutes of high emissions of ultrafine particles with d < 40 nm were observed. These particles are most likely formed by nucleation processes behind the wet-ESP from gas-phase constituents of the stack gas.

Aerosols↗
PubMed2000

There is more to monitoring a nuclear power plant than meets the eye.

A fundamental challenge in studying cognitive systems in context is how to move from the specific work setting studied to a more general understanding of distributed cognitive work and how to support it. We present a series of cognitive field studies that illustrate one response to this challenge. Our focus was on how nuclear power plant (NPP) operators monitor plant state during normal operating conditions. We studied operators at two NPPs with different control room interfaces. We identified strong consistencies with respect to factors that made monitoring difficult and the strategies that operators have developed to facilitate monitoring. We found that what makes monitoring difficult is not the need to identify subtle abnormal indications against a quiescent background, but rather the need to identify and pursue relevant findings against a noisy background. Operators devised proactive strategies to make important information more salient or reduce meaningless change, create new information, and off-load some cognitive processing onto the interface. These findings emphasize the active problem-solving nature of monitoring, and highlight the use of strategies for knowledge-driven monitoring and the proactive adaptation of the interface to support monitoring. Potential applications of this research include control room design for process control and alarm systems and user interfaces for complex systems.

Cognitive Science↗
PubMed2006

Effects of influent COD/N ratio and internal recycle ratio on nitrogen removal efficiency in the KNR process.

In this study, with the KNR process that has many advantages, the nitrogen removal efficiency of KNR was experimentally investigated at various COD/N ratios of influent conditions. The optimal operating condition of internal recycle ratio was evaluated. The TN removal efficiencies were 59.1, 72.5 and 75.9% at the COD/N ratios of 3, 5 and 7, respectively. These high removal efficiencies resulted from high denitrification rate in UMBR with high microorganism concentration. Furthermore, specific endogenous denitrification at MLVSS of 10.3 g/L that is similar to MLVSS in UMBR was over two times higher than that at MLVSS of 2.06 g/L. This result suggests that endogenous denitrification rate in UMBR is so high that the requirement of an external carbon source can be saved. As the internal recycle ratio increased from 100 to 400%, the TN removal efficiency also improved from 69.5 to 82.9%, and the optimal internal recycle ratio was 300%.

Aerobiosis↗
PubMedDate not supplied

[Results of early surgical treatment of intracranial aneurysm. Preliminary report].

The authors report their preliminary experiences with early (within 72 hours after haemorrhage) operations in cases of intracranial aneurysms. Out of 131 patients operated on from April 1985 to March 1986 in the Department of Neurosurgery, Medical Academy in Warsaw 20 were qualified for surgical intervention immediately after haemorrhage. In 13 cases Nimodipine (Nimotop) was given locally during the operation and in the postoperative period. The schedule of drug administration is shown. In 15 cases (75%) a very good result was noted, in 3 (15%) major signs of focal brain damage were observed within 6 months after the operation. Two patients (20%) died. In 4 cases neurological focal signs developed 4-5 days after subarachnoid haemorrhage due to ischaemia confirmed with CT. The operative conditions during early operations, and the approach to the vessels at the base of the brain were as good as during delayed operations.

Adult↗
PubMed1981

Performance characteristics of conditioned blood pressure elevations in the baboon.

Operant conditioning of diastolic blood pressure elevation was accomplished in six baboons (Papio sp.) by a procedure using food delivery when diastolic pressure was maintained above a prespecified level, and shock delivery when diastolic pressure remained below that level. Data from steady-state performance indicated a rise in diastolic pressure by a median 22 mm Hg when the daily session was begun. Elevated levels of diastolic blood pressure and low shock frequencies were maintained throughout the 12-hour session. The frequency and duration of shifts in diastolic pressure to below criterion level were found to be variable during the first 1-2 hours but were stable throughout the remainder of the session. Heart rate had a phasic temporal pattern over the 12-hour session, characterized for most subjects by a rate increase at session onset followed by a rate decrease. Analysis of individual performance records showed that the blood pressure increases could occur without concomitant elevations in heart rate.

Animals↗
PubMed1989

Memory traces in spinal cord produced by H-reflex conditioning: effects of post-tetanic potentiation.

Operant conditioning of the wholly spinal, largely monosynaptic triceps surae H-reflex in monkeys causes changes in lumbosacral spinal cord that persist after removal of supraspinal influence. We evaluated the interaction between post-tetanic potentiation and these memory traces. Animals in which the triceps surae H-reflex in one leg had been increased or decreased by conditioning were deeply anesthetized, and monosynaptic reflexes to L6-S1 dorsal root stimulation were recorded before and after tetanization from both legs for 3 days after thoracic cord transection. Animals remained anesthetized throughout and were sacrificed by overdose. Reflex asymmetries consistent with the effect of H-reflex conditioning were present after transection and persisted through the 3 days of study. Tetanization affected conditioned leg and control leg reflexes similarly. This finding suggests that, while post-tetanic potentiation and probably H-reflex conditioning alter Ia synaptic transmission, the two phenomena have different mechanisms.

Animals↗
PubMedDate not supplied

Ethanol self-administration in ALKO rats: I. Effects of selection and concentration.

The ALKO Alcohol Accepting (AA) rats and Alcohol Non-Accepting (ANA) rats were used to study the relationship between ethanol preference in a two-bottle choice paradigm and oral ethanol self-administration in an operant conditioning paradigm. Ethanol served as a positive reinforcer in the preferring AA line. Under a continuous reinforcement schedule (FR 1), ethanol deliveries were consistently greater than water (vehicle) deliveries and varied as an orderly inverted U-shaped function of ethanol concentration. Conversely, in nonpreferring ANA animals, ethanol did not serve as a reinforcer. Findings obtained with the AA rats were compared with those obtained with Sprague-Dawley rats. Sprague-Dawley rats maintained higher levels of responding and greater ethanol intake, relative to AA rats, at all concentrations of ethanol tested. The data are consistent with evidence that genotype is a critical factor in determining the extent to which ethanol serves as a reinforcer. The results also suggest that ethanol preference and the maintenance of ethanol reinforced behavior under operant conditions appear to have some common mechanisms. However, since the selection for ethanol preference in AA rats apparently did not maximize the maintenance of ethanol-reinforced behavior in an operant paradigm, ethanol drinking behavior in the preference paradigm may not be completely generalizable to that observed in the operant model.

Animals↗
PubMed2003

Opioids, cocaine, and food change runtime distribution in a rat runway procedure.

RATIONALE: The nature of the relationship between the dose of a drug of abuse and its reinforcing effect has come under close scrutiny. It is currently debated if the steep ascending part of the biphasic dose-response curve typically obtained in multiple-dosing lever-press-based operant conditioning procedures represents a satiety-driven, all-or-none response or if the response is gradual and tightly adjusted to the various doses of the reinforcer. OBJECTIVES: Dose-response relationships of drug reinforcers (remifentanil, alfentanil, morphine, cocaine) as well as a physiological reinforcer, i.e. food (sweetened condensed milk) were investigated in a different operant conditioning paradigm, i.e. a runway procedure. METHODS: Administration of the mu opioid receptor agonists remifentanil (0.0032-0.1 mg/kg IV), alfentanil (0.032 mg/kg IV), morphine (0.032-1 mg/kg IV), the psychostimulant cocaine (0.001-0.1 mg/kg IV) or sweetened condensed milk (diluted 1:100-1:3 in water) was made contingent upon alley running for male Sprague-Dawley rats. RESULTS: All drug reinforcers dose-dependently decreased runtimes and, more importantly, significantly increased the percentage of runs at a certain speed (> or =10 cm/s) from an average 29% to an average 71% (water versus milk, 22% versus 83%). CONCLUSION: Both drug- and food reinforcers produced a discontinuous, qualitative change in the rats' operant behavior rather than a simple gradual increase along a continuum, an effect that could be seen clearly only after a histogram analysis of runtime distribution.

Alfentanil↗
PubMed2003

Fermentation monitoring using multisensor systems: feasibility study of the electronic tongue.

The electronic tongue based on an array of 30 non-specific potentiometric chemical sensors has been applied to qualitative and quantitative monitoring of a batch fermentation process of starting culture for light cheese production. Process control charts were built by using PLS regression and data from fermentations run under "normal" operating conditions. Control charts allow discrimination of samples from fermentation batches run under "abnormal" operating conditions from "normal" ones at as early as 30-50% of fully evolved fermentations. The capability of the electronic tongue to quantify concentrations of important organic acids (citric, lactic and orotic) in the present type of fermentation media was demonstrated. Average prediction errors were assessed in the range 5-13% based on test set validation. Correlation between peptide profiles determined using HPLC and the electronic tongue output was also established. The electronic tongue was demonstrated to be a promising tool for fermentation process monitoring and quantitative analysis of growth media.

Journal Article↗
PubMedDate not supplied

Chaotic dynamics of a food web in a chemostat.

We analyze a mathematical model of a simple food web consisting of one predator and two prey populations in a chemostat. Monod's model is employed for the dependence of the specific growth rates of the two prey populations on the concentration of the rate-limiting substrate and a generalization of Monod's model for the dependence of the specific growth rate of the predator on the concentrations of the prey populations. We use numerical bifurcation techniques to determine the effect of the operating conditions of the chemostat on the dynamics of the system and construct its operating diagram. Chaotic behavior resulting from successive period doublings is observed. Multistability phenomena of coexistence of steady and periodic states at the same operating conditions are also found.

Animals↗