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PubMed1994

Designing microbial systems for gene expression in the field.

Unlike bacteria grown in the laboratory, genetically modified microorganisms destined for deliberate release as agents of bioremediation, or as live vaccines must be able to express their phenotype under the control of external signals that are present in the environment into which they are released. This is a major difference from other biotechnological processes (for example, in a bioreactor) in which the working conditions can be fixed at the will of the operator. In the field, operating conditions are determined by the external environment. The main problem is, therefore, how to programme bacteria physiologically and genetically to express the desired phenotype at the correct level and the right time, under physicochemical circumstances over which we have little or no control. This challenge has encouraged the development of new broad-host-range expression systems specifically tailored for bacteria, particularly Pseudomonas, but also various other Gram-negative organisms, for use in the field.

Biodegradation, Environmental↗
PubMed1997

A clinical investigation of the possible effects of long-term habituation of sexual arousal in assisted covert sensitization.

Behavior principles are naturally implicated in most of the behavior therapy techniques used in the treatment of sexual dysfunctions and sexual disorders. Hypotheses differ, however, in the extent to which behavior therapy procedures emphasize the classical conditioning of sexual arousal (e.g. penile responses) or the operant conditioning of deviant sexual behavior patterns, or other often ignored behavior principles such as habituation. The purpose of the present case study is to investigate the possibility that at least part of the clinical effects of a widely used behavior therapy technique for sexual deviations, covert sensitization, may directly involve habituation processes. Results of the assisted covert sensitization case study indicate that, while expected decrements in sexual arousal to sexually inappropriate stimuli were observed, decrements in sexual arousal and self-report were also observed for sexually appropriate stimuli which received no aversive consequences, only repeated stimulus presentation over time. It is argued that habituation processes need further empirical investigation as a potential behavioral mechanism in the beneficial clinical effects usually noted in covert sensitization procedures.

Adolescent↗
PubMed1997

Computational neural networks for predictive microbiology. II. Application to microbial growth.

The growth of a specific microorganism on a certain food is influenced by a number of environmental factors such as temperature, pH, and salt concentration. Methods that delineate the history of the growth of microorganisms are always subject to a considerable debate and scrutiny in the field of predictive microbiology. Regardless of its types, a growth model (e.g., modified Gompertz model) contains several parameters that vary depending on the microorganisms/food combination and the associated prevailing environmental conditions. The growth model parameters for a set of operating conditions are commonly determined from expressions developed via multiple linear regressions. In the present study, a substitute for the nonlinear regression-based equations is developed using computational neural networks. Computational neural networks are applied herein on experimental data pertaining to the anaerobic growth of Shigella flexneri. Results have indicated that predictions by neural networks offer better agreement with experimental data as compared to predictions obtained via corresponding regression equations.

Neural Networks, Computer↗
PubMed2004

Efficient control system for low-concentration inorganic gases from a process vent stream: application of surfactants in spray and packed columns.

Control of low-concentration pollutants from a semiconductor process vent stream using a wet-scrubbing technique is a challenging task to meet Taiwan environmental emission standards. An efficient wet-scrubber is designed on a pilot scale and tested to control low concentration acid and base waste-gas emission. The scrubber system consisted of two columns, i.e., a fine spray column [cutoff diameter (based on volume), Dv(50) = 15.63 microm; Sauter mean diameter (SMD) = 7.62 microm], which is especially efficient for NH3 removal as the pH of the spraying liquid is approximately 7 followed by a packed column with a scrubbing liquid pH approximately 9.0 mainly for acids removal. It is observed that use of the surfactants in low concentration about 10(-4) M and 10(-7) M in the spray liquid and in the scrubbing liquid, respectively, remarkably enhances the removal efficiency of the system. A traditional packed column (without the spray column and the surfactant) showed that the removal efficiencies of NH3, HF, and HCl for the inlet concentration range 0.2 to 3 ppm were (n = 5) 22.6+/-3.4%, 43.4+/-5.5%, and 40.4+/-7.4%, respectively. The overall efficiencies of the proposed system (the spray column and the packed column) in the presence of the surfactant in the spray liquid and in the scrubbing liquid forthese three species were found to increase significantly (n = 5) from 60.3+/-3.6 to 82.8+/-6.8%, 59.1+/-2.7 to 83.4+/-4.2%, and 56.2+/-7.3 to 81.0+/-6.7%, respectively. In this work, development of charge on the gas-liquid interface due to the surfactants has been measured and discussed. It is concluded that the presence of charge on the gas-liquid interface is the responsible factor for enhancement of the removal efficiency (mass-transfer in liquid phase). The effects of the type of surfactants, their chain length, concentration in liquid, etc. on the removal efficiency are discussed. Since the pilot tests were performed under the operating conditions similar to most of the wet-scrubbers operated in semiconductors manufacturing facilities for inorganic pollutants, this study can be applied to modify the existing wet-scrubbers to enhance the removal efficiencies, especially for low-concentration pollutants.

Aerosols↗
PubMed2006

Characterization of a microscale cyclical electrical field flow fractionation system.

A microscale cyclical electrical field flow fractionation (CyElFFF) channel is characterized with regard to the effect of various operating parameters and comparison made to recent theoretical developments. Challenges associated with various operating conditions are reported along with some of the optimized operating parameters. The effect of retention wall choice, an offset voltage, relaxation steps, and flow rates, along with the basic operating parameters of voltage, frequency, and electrophoretic mobility are reported. Retention of polystyrene nanoparticle standards is accomplished and the first separations using this technique in a microscale system are also demonstrated. Relaxation steps and offset voltages are found to be effective in eliminating early peaks and in improving plate heights. Plate heights were also found to decrease with increasing flow rates, which is the opposite of the behavior seen in most existing chromatographic systems. The experimental results are compared to the analytical and empirical models of CyElFFF and found to be compatible. Suggestions are made for improving the separation and analysis methods used with CyElFFF.

Journal Article↗
PubMed2004

Minimalism context-aware displays.

Despite the rapid development of cyber technologies, today we still have very limited attention and communication bandwidth to process the increasing information flow. The goal of the study is to develop a context-aware filter to match the information load with particular needs and capacities. The functions include bandwidth-resolution trade-off and user context modeling. From the empirical lab studies, it is found that the resolution of images can be reduced in order of magnitude if the viewer knows that he/she is looking for particular features. The adaptive display queue is optimized with real-time operational conditions and user's inquiry history. Instead of measuring operator's behavior directly, ubiquitous computing models are developed to anticipate user's behavior from the operational environment data. A case study of the video stream monitoring for transit security is discussed in the paper. In addition, the author addresses the future direction of coherent human-machine vision systems.

Awareness↗
PubMed1990

Analysis of low molecular weight hydrocarbons including 1,3-butadiene in engine exhaust gases using an aluminum oxide porous-layer open-tubular fused-silica column.

A method for the quantitative analysis of individual hydrocarbons in the C1-C8 range emitted in engine exhaust gases is described. The procedure provides base-line or near base-line resolution of C4 components including 1,3-butadiene. With a run time of less than 50 min, the light aromatics (benzene, toluene, ethyl benzene, p- and m-xylene, and o-xylene) are resolved during the same analysis as aliphatic hydrocarbons in the C1-C8 range. It is shown that typical 1,3-butadiene levels in engine exhaust are about 5 ppm at each of two engine conditions. Aromatic hydrocarbon levels show a dependence on engine operating conditions, benzene being about 20 ppm at high speed and about 40 ppm at idle.

Aluminum Oxide↗
PubMed1996

Automatic centering of the microscope image for vitreoretinal surgery.

PURPOSE: The authors report on their device, the surgical image tracker, which provides automatic compensation for movements of the surgical image within the microscope field of view, during vitreoretinal procedures. METHODS: The authors developed a compact device acting as an automatic image tracker, based on video monitoring of the surgical image and translation of the operating microscope. Basic components are a standard color charge-coupled device camera and a specifically designed frame grabber for discrimination and tracking of the target image. Operation of the device is fully compatible with the usual pedal adjustments. RESULTS: Ready, fast, and correct automatic centering of the microscope field of view has been achieved successfully in all typical operating conditions. Video recording always is equally well centered. System operation also is effective with panoramic optics and diffuse illumination. CONCLUSION: The surgical image tracker appears to be a valuable tool to obtain well auto-centered surgical images, eliminating a bothersome task during vitreoretinal surgery.

Humans↗
PubMed1964

SOME PHARMACOLOGICAL EFFECTS OF A SERIES OF TRYPTAMINE DERIVATIVES.

The methods of synthesis and some pharmacological properties of a number of N-substituted tryptamines are described. Peripheral vasopressor activity decreased with increase in complexity of the substituent and was not related to toxicity or to behavioural activity. Activity in increasing the rectal temperature of rabbits appeared to parallel modifications in the open-field behaviour of rats. Some compounds were investigated for their ability to block a conditioned avoidance-response in rats and to affect operant conditioning in cats. Evidence is presented which suggests that the tryptamine derivatives are metabolized in vivo to more active forms.

Amines↗
PubMed1993

A new drug delivery system (DDS) development using plasma-irradiated pharmaceutical aids. IV. Controlled release of theophylline from plasma-irradiated double-compressed tablet composed of polycarbonate as a single wall material.

A controlled-release tablet can be obtained by oxygen plasma irradiation on the outer layer double-compressed tablets prepared from theophylline as a core material and polycarbonate derived from bisphenol A (PC) as a single wall material, making this possible that PC is of intramolecular bifunctionality, crosslinkable phenyl group and degradable carbonate group as an effect of plasma irradiation. It was shown that the dissolution profiles can be varied so as to cause release of theophylline at different rates, depending on the set of conditions chosen for tablet manufacturing as well as plasma operational conditions.

Drug Compounding↗
PubMed1999

Anterior shoulder instability in sport: current management recommendations.

In the young athlete, anterior shoulder dislocations are common injuries that usually result in recurrent instability, and often require surgical treatment. Non-operative treatment remains the initial recommended course for most conditions. Operative treatment has advanced to more anatomical repairs, both open and arthroscopic. The purpose of this paper is to review the evaluation and treatment of anterior shoulder instability, to include acute dislocations, acute subluxations and recurrent instability.

Adult↗
PubMed1992

Assessment of a neuroradiology picture archiving and communication system in clinical practice.

The goal of this study was to determine if our neuroradiology picture archiving and communication system (PACS) is capable of improving the efficiency and function of the management and review of neuroradiologic images. A neuroradiology PACS module developed in our department was evaluated in the clinical environment from February 1990 through July 1991. The overall evaluation focused on three aspects: (1) image delivery performance, (2) system availability, and (3) user acceptance. Image delivery performance was evaluated by analyzing the time spent on each modularized task with both the film-based system and the PACS system. The system availability was examined by observing the downtime occurrence and uptime probability of individual hardware components in the PACS module. User acceptance was evaluated through a survey done with the display workstation. Under regular operating conditions, the PACS outperforms the current film-based operation. The overall PACS module availability is more than 92%, with the display workstation available more than 99% of the time. The overall user acceptance of the system is 3.4 on a four-point ranking scale. This study has demonstrated the full functionality and clinical usefulness of our neuroradiology PACS. On the basis of the results of this study, a large-scale PACS has been designed and implemented in our department.

Computers↗
PubMed1981

Deliberate hypotension for middle ear microsurgery.

By means of groups of one hundred patients undergoing middle ear microsurgery, we compared two hypotensive anesthesia techniques combining halothane, a non-depolarising myorelaxant and a beta adrenoreceptor blocking agent. Practolol, a beta 1 receptor blocker was administered to the patients of group A while those of group B received labetalol, a more recently introduced alpha and beta receptor blocker. The duration of microsurgery for each type of pathology was identical in both groups but the operation conditions (mostly the amount of bleeding) were better in group B (statistically significant). Moreover, the mean delivered halothane concentration could be reduced by 20% (from 0.85% to 0.68%). Thirty patients undergoing tympanoplasty were followed up for several months to determine the the importance of peroperative conditions in relation to the functional result of these operations. Excessive bleeding hinders the surgeon and the positioning of the implant and also, as confirmed by this study, makes the success of the tympanoplasty uncertain. Two factors likely to predispose the patient to bleeding (and able to be brought under control preoperatively) have been highlighted: these are overweight (obese status about 80 kg) and a systolic arterial blood pressure at rest above 140 torr. The various agents which were used and the reasons for their choice are discussed.

Adrenergic beta-Antagonists↗
PubMed2004

Effects of drugs that potentiate GABA on extinction of positively-reinforced operant behaviour.

Extinction following positively reinforced operant conditioning reduces response frequency, at least in part through the aversive or frustrative effects of non-reinforcement. According to J.A. Gray's theory, non-reinforcement activates the behavioural inhibition system which in turn causes anxiety. As predicted, anxiolytic drugs including benzodiazepines affect the operant extinction process. Recent studies have shown that reducing GABA-mediated neurotransmission retards extinction of aversive conditioning. We have shown in a series of studies that anxiolytic compounds that potentiate GABA facilitate extinction of positively reinforced fixed-ratio operant behaviour in C57B1/6 male mice. This effect does not occur in the early stages of extinction, nor is it dependent on cumulative effects of the compound administered. Potentiation of GABA at later stages has the effect of increasing sensitivity to the extinction contingency and facilitates the inhibition of the behaviour that is no longer required. The GABAergic hypnotic, zolpidem, has the same selective effects on operant extinction in this procedure. The effects of zolpidem are not due to sedative action. There is evidence across our series of experiments that different GABA-A subtype receptors are involved in extinction facilitation and anxiolysis. Consequently, this procedure may not be an appropriate model for anxiolytic drug action, but it may be a useful technique for analysing the neural bases of extinction and designing therapeutic interventions in humans where failure to extinguish inappropriate behaviours can lead to pathological conditions such as post-traumatic stress disorder.

Animals↗
PubMedDate not supplied

[Search of optimum survival conditions for lactic acid bacteria in powders obtained by spray drying of yoghurt].

The paper reports the results of two spray-drying tests carried out on yogurt as such or previously neutralized. The operating conditions of the drying operation were such that the temperature of the product didn't exceed 80 degrees C, and the residual moisture of the powder was about 10%, slightly higher than the B.E.T. monolayer value. The decrease of total counts was three and two decimal reductions respectively for the natural and neutralized product. This latter gave also much higher viability index as determined in a "fermenting activity" test. Also, the analyses, related to the quality of the protein fraction, strongly support the opportunity of neutralization before drying. In storage tests carried out during 8 months the survival data were higher at 5% relative humidity (corresponding to 7-8% humidity) and at 5 degrees C temperature. In all cases the better results were obtained from the powders of neutralized yogurt, even in comparison with a freeze-dried sample obtained from the natural product. The typical shape of the sorption isotherms of these products suggests that the optimum process as regard to microorganisms' survival consists in drying the neutralized product up to residual humidities of 8-10%, followed by storage, in humidity-proof containers, at temperatures of about 5 degrees C.

Dairy Products↗
PubMedDate not supplied

Transport in a grooved perfusion flat-bed bioreactor for cell therapy applications.

This study considers the transport of oxygen (a growth-associated solute) and lactate (a metabolic byproduct) in a flat-bed perfusion chamber modified to retain cells through the addition of grooves, perpendicular to the direction of flow, at the chamber bottom. The chamber has been successfully applied to hematopoietic cell culture and may be useful for other basic and applied biomedical applications. The objective of this study is to characterize the culture environment in terms of solute transport under various operational conditions. This will allow one to improve the design and operating strategy of the perfusion system for maximizing cell numbers. The system is numerically simulated using the finite element package FIDAP. The reaction kinetics describing oxygen uptake by cells are simplified to zero order to give an upper bound for the oxygen consumption. A flat-bed chamber without grooves is considered here as a benchmark. We show that the growth environment is not oxygen limited (local oxygen concentration above 10 microM) for a variety of flow rates and culture conditions (qO2 = 0.1 micromol/(10(6) cells h)). With a medium flow rate of 2.5 mL/min through the reactor, the model predicts that the 29-cm2 reactor can support at least 33.4 x 10(6) total cells when the inlet medium is in equilibrium with high (20%) oxygen concentration. The culture becomes oxygen limited however for the same flow rate for low (5%) oxygen concentration and can only support 7.2 x 10(6) total cells. Comparison of grooved vs nongrooved chambers reveals that the presence of grooves only affects solute transport on a local scale. This result is attributed to the small size (200 microgram) of the cavities relative to the chamber dimensions. The comparison also yields an empirical relation that allows for rapid estimation of oxygen and lactate concentrations in the grooves using only the numerical simulation of the simpler nongrooved chamber. Finally, our investigation shows that, while decreasing the spacing between cavities decreases the total number of cells the reactor can support, the efficiency of the reactor is increased by 25% (on an area basis) without growth restriction.

Bioreactors↗
PubMed2006

Dense gas processing of micron-sized drug formulations incorporating hydroxypropylated and methylated beta-cyclodextrin.

PURPOSE: Because of their importance in pharmaceutical applications, hydroxypropyl-beta-cyclodextrin and methyl-beta-cyclodextrin have been selected to study the formation of micronized complexes incorporating active pharmaceutical ingredients (APIs) and cyclodextrins (CDs) by dense gas (DG) processing. METHODS: A single-step DG technique was used as an alternative to conventional methods for the manufacturing of API/CD complexes. The DG technology is highly attractive in the pharmaceutical industry because of its potential to generate micronized particles with controlled particle size distributions at moderate operating conditions. The effect of the aerosol solvent extraction system (ASES) processing on the dissolution performance of naproxen (NPX) was examined. RESULTS: The CDs were produced as microspheres smaller than 3 microm. The coprecipitation of each CD with NPX resulted in the production of microparticles with enhanced dissolution rates. CONCLUSIONS: The ASES was operated under mild conditions and generated micron-sized spherical particles that could be of particular interest in formulations for pulmonary delivery. Particular advantages of the technique are that (1) nontoxic solvents are used, and (2) it is suitable for the processing of thermally labile compounds. The proposed process can create opportunities to improve current administration routes and exploit novel delivery systems for drug formulations incorporating CDs.

2-Hydroxypropyl-beta-cyclodextrin↗