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At least 1,063 records · Page 59Linked to original sources
PubMed2001

Impact of solids management on nutrient ratios for in-line wastewater prefermenters.

The full-scale evaluation of in-line prefermentation effects on wastewater nutrient ratios was performed under three different sludge operating conditions, with regards to sludge elutriation rates (0.7, 2.2 and 3.7 kg dry sludge/m3 raw sewage) and the corresponding sludge ages (17.3, 2.5 and 7.5 days). At all three operating conditions the TKN/COD ratio increased (64, 46 and 20% respectively), with an average ratio of 0.057 mg N/mg COD in the raw sewage increasing to 0.082 mg N/mg COD in the settled sewage. These ratio increases can limit the use and performance of certain biological nutrient removal process configurations. This study has further highlighted the importance to counterbalance fermentation, thickening and solids removal requirements in a single tank in-line prefermenter. The minimum suspended solids removal (33%) was achieved at the lowest settled sludge solids content (4.3%), against a corresponding maximum volatile fatty acid generation rate (5.7 mg VFA/l/h). The total solids and volatile fatty acid concentration profiles down the prefermenter tank depth were determined at a high sludge blanket level condition. It was demonstrated that the accumulated constituent mass inventory increase was about constant throughout the water and sludge layers respectively under such operational conditions.

Biodegradation, Environmental↗
PubMed1994

Second-order conditioning and Pavlovian conditioned inhibition: operational similarities and differences.

Procedures for establishing second-order excitation (conditioned stimulus [CS] 1-unconditioned stimulus [US] trials followed by CS2-CS1 trials) are highly similar to those for Pavlovian conditioned inhibition (CS1-US trials interspersed with CS2-CS1 trials). Conditioned suppression in rats was used to identify the critical operational differences that result in second-order excitation as opposed to Pavlovian inhibition. No, few, or many CS2-CS1 trials were either interspersed with or given after CS1-US trials. CS2 proved excitatory only after few CS2-CS1 trials, either interspersed or sequential (Experiment 1). In contrast, CS2 proved inhibitory on both summation (Experiment 2) and retardation (Experiment 3) tests only after many CS2-CS1 trials, and then only when the excitatory status of CS1 was preserved. Apparently, the critical difference for establishing second-order excitation or Pavlovian inhibition is the number of CS2-CS1 pairings.

Animals↗
PubMed1975

Operant conditioning-based behavior modification: one approach to treating somatic disorders.

The applicability of behavior modification as a process for treating somatic difficulties is examined within the framework of measurement, modification, and evaluation. Illustrations of this process are presented throughout. In particular, the last section of the paper gives an example of a currently operative and multifaceted approach to the problem of obesity. Among the topics considered herein are the use of behavioral contracts that specify ameliorative weight reduction practices and the assessment as well as manipulation of eating speed.

Attention↗
PubMed2004

Particle collection efficiency and particle re-entrainment of an electrostatic precipitator in a sewage sludge incineration plant.

In several recent studies it was shown that high atmospheric loads of submicrometer particles in the size range below 500 nm have strong impact on human health. Therefore, extensive research concerning the reduction of fine particle emissions is needed to further improve air quality. Regarding health effects, especially the emission characteristics of fine and ultrafine particles emerging from anthropogenic sources such as combustion processes are of special interest. This study shows that the emission characteristic of an electrostatic precipitator (ESP) due to re-entrainment of fine particles and their subsequent release into the atmosphere can be significantly lowered by application of different operating conditions. For this purpose the particle collection efficiency of an ESP was studied in a municipal sewage sludge incineration plant. Particles were sampled under different operating conditions upstream and downstream from the ESP, and the particle number concentrations were measured simultaneously with aerodynamic particle sizers. In addition, the size distribution of the particles downstream from the ESP was measured with high time resolution by an electrical low-pressure impactor to investigate the particle re-entrainment into the flue gas. To determine the influence of operating conditions, different rapping cycles were investigated regarding their impact on the collection efficiency and the subsequent particle re-entrainment.

Air Pollution↗
PubMed2005

[Low doses of aprotinin in reducing blood loss and allogenic transfusions in operation under conditions of extracorporeal circulation with using cell saver].

A blind prospective randomized investigation included 109 patients with ischemic heart disease undergoing operations of coronary shunting under conditions of extracorporeal circulation. It was shown that aprotinin in the dose of 3 ppm KIU in operations of coronary shunting under conditions of reserving autoblood, extracorporeal circulation and using cell saver facilitates reducing postoperative blood loss, but does not lead to less frequent allogenic transfusions.

Aprotinin↗
PubMed1993

Local anaesthesia for eye surgery without a facial nerve block.

Traditionally, local anaesthesia for cataract surgery requires retrobulbar blockade to be supplemented with a facial nerve block in order to prevent blepharospasm. In this study retrobulbar block using a larger volume of local anaesthetic without facial nerve block is compared with the combined technique in 50 patients. The adequacy of the two techniques was assessed by the surgeon according to eye motility (in four different planes), lid motility and eye softness and an overall surgical assessment was made at the end of the procedure. Blepharospasm did not occur. The operating conditions were equally good in both groups (p > 0.05). These results suggest that good operating conditions for cataract operations can be provided by retrobulbar block alone without supplementary facial nerve block.

Aged↗
PubMedDate not supplied

Operant GSR conditioning with cool air reinforcement.

Two groups of 20 Ss each run individually in a soundproff chamber heated to 115 F and humidified to 100%. Ss in the experimental group received brief presentation of cool air contingent upon wmitted GSRs during 20 min of acquisition. Control Ss were matched on at a time in operant rate and were yoked one at a time to receive the cool air on a response-independent schedule. Both groups increased significantly in rate of unelicited GSRs during acquisition, with the experimental Ss' curve rising more rapidly and both groups attaining equivalent terminal levels. During extinction, the groups maintained high levels of responding and did not differ. Examination of basal skin conductance data ruled our an activation hypothesis. In the control Ss, terminal response frequency was significantly correlated with percentage of fortuitous response-contigent reinforcement. It was concluded that both croups were conditioned, with the controls receiving intermittent reinforcement sufficiently often to elevate their responding. The cool air was judged to be an effective reinforcer of unelicited GSRs, perhaps more effective than those used in previous studies.

Air↗
PubMed1990

Reproducible methods for calibrating the backscattered electron signal for quantitative assessment of mineral content in bone.

Backscattered electron (BSE) imaging shows promise for orthopaedic and bone research. BSE images of bone may be captured on-line directly from the scanning electron microscope (SEM), and then analyzed to produce a backscattered electron profile (BSEP), a modified image graylevel histogram which is representative of the mineral content in bone. The goals of this work were 1) develop a reproducible graylevel calibration technique for bone specimens, and 2) determine a conservative time interval during which SEM operating conditions would remain stable. Calibration standards containing pure aluminum and pure magnesium wires were placed in the SEM with human cancellous bone. Baseline imaging conditions were first established by adjusting the SEM until the bone image displayed good resolution and graylevel separation between regions of different mineral content. Microscope brightness and contrast controls were randomly changed to initiate the new operating conditions of another imaging session, and graylevel values from the calibration metals were used to readjust the microscope back to baseline operating conditions. Weighted mean graylevel values of the BSEPs from calibration trials were compared to those of the baseline. Data showed that bone images could be reproduced within 1.2 percent. It was also concluded that our equipment required calibration checks at 20 minute intervals.

Animals↗
PubMed1987

Two-muscle coordination versus natural treadmill locomotion.

When a single-muscle learned behavior was superimposed upon natural human treadmill locomotion, in previous work, it operated as a self-contained behavioral unit. The new behavior altered some features, however, of ongoing stepping patterns. These findings prompted broader consideration of how individual muscle actions combine to form large, patterned ensembles. Accordingly, the present experiment constructed a larger, double-muscle learned behavior to see if it would compete with natural treadmill locomotion or combine with it harmoniously. A demanding requirement was made for in-phase bilateral EMG and contraction by rectus femoris (RF), in opposition to its natural out-of-phase interlimb pattern. EMG bursts were controlled, through computer-assisted operant conditioning, by a flash shortly after left heel strike. The new, double ensemble was conditioned rapidly, within 1-6 days, for all four adults. Harmonious stepping continued, for the most part, with little alteration in step cycle timings. Leg positioning was modified appreciably, however, pointing to complex neural mechanisms. The evidence argued that operant conditioning can construct fine-grained behaviors and also participate powerfully across the full range of single- and interlimb coordination.

Adult↗
PubMed2002

RWPV bioreactor mass transport: earth-based and in microgravity.

Mass transport and mixing of perfused scalar quantities in the NASA Rotating Wall Perfused Vessel bioreactor are studied using numerical models of the flow field and scalar concentration field. Operating conditions typical of both microgravity and ground-based cell cultures are studied to determine the expected vessel performance for both flight and ground-based control experiments. Results are presented for the transport of oxygen with cell densities and consumption rates typical of colon cancer cells cultured in the RWPV. The transport and mixing characteristics are first investigated with a step change in the perfusion inlet concentration by computing the time histories of the time to exceed 10% inlet concentration. The effects of a uniform cell utilization rate are then investigated with time histories of the outlet concentration, volume average concentration, and volume fraction starved. It is found that the operating conditions used in microgravity produce results that are quite different then those for ground-based conditions. Mixing times for microgravity conditions are significantly shorter than those for ground-based operation. Increasing the differential rotation rates (microgravity) increases the mixing and transport, while increasing the mean rotation rate (ground-based) suppresses both. Increasing perfusion rates enhances mass transport for both microgravity and ground-based cases, however, for the present range of operating conditions, above 5-10 cc/min there are diminishing returns as much of the inlet fluid is transported directly to the perfusion exit. The results show that exit concentration is not a good indicator of the concentration distributions in the vessel. In microgravity conditions, the NASA RWPV bioreactor with the viscous pump has been shown to provide an environment that is well mixed. Even when operated near the theoretical minimum perfusion rates, only a small fraction of the volume provides less than the required oxygen levels.

Bioreactors↗
PubMed2004

Reduced sensitivity to reward in CB1 knockout mice.

RATIONALE: Previous studies have demonstrated that the activation and blockade of the cannabinoid type 1 receptor (CB1) leads to an enhancement and decrease of the consumption of food and other orally ingested reinforcers, respectively. OBJECTIVE: To gain further knowledge about the role of CB1 in sucrose/saccharin reinforcing efficacy and intake, we tested CB1 knockout (CB1-KO) and littermate wild-type (WT) control mice in several self-administration experimental protocols. METHODS: Operant (fixed or progressive ratio schedule) and non-operant conditioning procedures were used. In addition, a choice analysis based on the "matching law" as well as a microstructural analysis of the intra-session pattern of self-administration was performed. RESULTS: CB1-KO mice consume less sucrose under operant conditions or when using a two-bottle free choice procedure. Moreover, as revealed by additional behavioural analysis, CB1-KO mice exhibit a decreased sensitivity to the rewarding properties of sucrose. In agreement with this finding, the differences between WT and CB1-KO mice faded away when the palatability of sucrose was devaluated by adding quinine, but not when a non-caloric sweetener, saccharin, was available. CONCLUSIONS: These results demonstrate a modulatory role of CB1 in the determination of the rewarding properties of sucrose and probably, as suggested by previous studies, other reinforcers.

Animals↗
PubMed2000

A natural basis for efficient brain-actuated control.

The prospect of noninvasive brain-actuated control of computerized screen displays or locomotive devices is of interest to many and of crucial importance to a few 'locked-in' subjects who experience near total motor paralysis while retaining sensory and mental faculties. Currently several groups are attempting to achieve brain-actuated control of screen displays using operant conditioning of particular features of the spontaneous scalp electroencephalogram (EEG) including central mu-rhythms (9-12 Hz). A new EEG decomposition technique, independent component analysis (ICA), appears to be a foundation for new research in the design of systems for detection and operant control of endogenous EEG rhythms to achieve flexible EEG-based communication. ICA separates multichannel EEG data into spatially static and temporally independent components including separate components accounting for posterior alpha rhythms and central mu activities. We demonstrate using data from a visual selective attention task that ICA-derived mu-components can show much stronger spectral reactivity to motor events than activity measures for single scalp channels. ICA decompositions of spontaneous EEG would thus appear to form a natural basis for operant conditioning to achieve efficient and multidimensional brain-actuated control in motor-limited and locked-in subjects.

Biofeedback, Psychology↗
PubMed2004

Characterisation of an urban bus network for environmental purposes.

Since pollutant emissions are closely related to the operating conditions of vehicles, their evaluation usually involves studying these operating conditions (through bus instrumentation and monitoring under actual operation), the design of representative driving or engine test cycles and the measurement of pollutant emissions. A preliminary characterisation of the routes on a bus network should make it possible to identify typical routes, the driving conditions and pollutant emissions of which are then studied. Two approaches are envisaged and applied to the Paris area, for which a wealth of information is available, which should be transferable to other bus networks. Both approaches are based on factorial analysis and automatic clustering, to allow optimum description and the identification of a pertinent typology of the bus routes in several classes. The first attempt at characterisation is based on statistics relating to bus operations: route characteristics (length, dedicated bus lanes, number of stops, location of stops: schools, tourist sites, hospitals, railways or underground stations), travel time, commercial speed, annual statistics (number of passengers, number of vehicles per hour, total kilometres), the irregularity of travel (variation of travel times, injuries, congestion.), as well as information on the problems encountered (congestion, distribution of the passenger load, junctions, bends). A second approach is based on the analysis of the "urban context" in which buses are driven. Population, employment, housing, road network, traffic and places that generate or disturb traffic (schools, railway stations, shopping areas, etc.) are calculated for the Ile de France region, by cells of 100 x 100 m, and collected in a geographical information system (GIS). Statistical analyses enable a typology of these urban cells to be established, the main parameters being density, type of housing, road types and traffic levels. The bus routes are then analysed according to their itineraries across these typical areas (distances travelled in each type of area) using a similar approach. A comparison of the typologies obtained from operational data and from urban data highlights the advantages and disadvantages of the two approaches. The first result from these typologies is the selection of routes which are representative of the different classes, in order to instrument buses and record driving patterns. This method should also make it possible to link driving conditions and urban characteristics, and then to allocate pollutant emission factors to given geographical situations, in particular, in the context of emission inventories or impact studies.

Cities↗
PubMed1975

Activity in chronic schizophrenic patients: comparison of pimozide with fluphenazine in a double blind trial.

A double-blind crossover trial was carried out comparing pimozide with fluphenazine. The effects of the drugs on the activity of 20 chronic inert male schizophrenic patients were measured using nursing observations, psychiatric rating, and an operant conditioning method. When activity was assessed in these different ways, no significant difference was found between the two drugs on any of the measures. It is concluded that pimozide does not effectively increase the activity in such patients. It is considered that the free operant conditioning method used was shown to be a useful measure for comparing therapy in chronic schizophrenic patients.

Administration, Oral↗
PubMedDate not supplied

Testing strategies in behavioral teratology: III. Microanalysis of behavior.

After having been tested in a standard behavioral teratology test battery, as reported in Part I of this study, a random sample of male offspring of rat dams exposed to methylmercury starting two weeks prior to pairing until weaning were further tested in a wheel-shaped activity monitor and in an operant conditioning paradigm (spatial alternation discrete trial acquisition). In the activity monitor a non-significant increase in locomotor activity, a significant interaction between locomotion and radial activity monitor compartments and a significant increase in stereotyped locomotion was observed. While the preliminary training phases of operant conditioning showed only weak effects due to methylmercury, strong and highly significant increases of the number of unresponded trials and of the response latency, as well as of the session to session variation of these measures were detected during the spatial alternation schedule. A microanalysis of this observation revealed that the number of unresponded trials and its instability were affected in essence due to an increased number of response pauses, and to a lesser degree to an increased length of these pauses. In addition, short attention spans (number of trials responded between two pauses) were about four times more frequent in treated animals. The distributions of both response latency and duration were shifted significantly to longer values. These observations are interpreted as an indication of a reduced attention and behavioral stability, induced by the schedule challenge. This interpretation is compared with the signs of minimal brain dysfunction in school-children.

Animals↗
PubMedDate not supplied

Operant behavior as a technique for toxicity testing.

Behavioral toxicology is a discipline which has evolved out of the need for data on the effects of toxic agents on the function of the central nervous system. To date the field is divided over the question of which behavioral models to use to detect behavioral toxicities. Operant conditioning and schedule-controlled responding have been used as baselines for testing pharmacological agents for nearly 40 years, and there is no reason that the developing field of behavioral toxicology cannot take advantage of the lessons learned during this 40-year period. Behaviors maintained by operant conditioning procedures have proven to be sensitive to a wide range of chemicals. Using these procedures, behavior has been shown to; be sensitive to toxic agents, provide data relevant to the question of behavioral specificity, provide a stable baseline for extended periods of time, and allow for the assessment of specific functions such as temporal discrimination, learning and memory, and sensory system function.

Animals↗
PubMed2003

Efficient synthesis of serically constrained smmetrically alpha,alpha-disubstituted alpha-amino acids under operationally convenient conditions.

Homologation of the nucleophilic glycine equivalent Ni-Gly-PABP [Ni(II) complex of glycine Schiff base with 2-[N-(alpha-picolyl)amino]benzophenone (PABP)] 2 via alkyl halide alkylations and Michael addition reactions was systematically studied as a general method for preparing symmetrically alpha,alpha-disubstituted alpha-amino acids (sym-alpha,alpha-AA). The dialkylation reactions are conducted under operationally convenient conditions without recourse to inert atmosphere, dried solvents, and low temperatures, thus enjoying key advantages of the experimental simplicity and attractive cost structure. The method has been shown to be particularly successful for the dialkylation of complex 2 with activated and nonactivated alkyl halides, including propargyl derivatives, affording a generalized and practical access to the corresponding sym-alpha,alpha-AA. This study has also shown some limitation of the method, as it cannot be extended to alpha- or beta-branched alkyl halides or Michael acceptors to be used for the dialkylation of glycine equivalent 2. High chemical yields of the dialkylated products, combined with the simplicity of the experimental procedure, render this method worth immediate use for multigram scale preparation of the sym-alpha,alpha-AA.

Alkylation↗