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Results for “Optimization”

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PubMed2003

[Application of optimization management model of municipal solid waste from medium or small city of China].

According to the basic characteristics of municipal solid waste generated from medium or small city of China, the optimal management principles and programs for optimization management model suitable to them were put forward. By application of the model in case study, the optimal scenarios for the disposal of municipal solid waste from the planning system in 1999, 2005 and 2010 were calculated, which adequately validated and accounted for the advantages of optimization model by comparison of costs between optimization scenarios and former scenarios.

China↗

PubMed1992

[Optimization of the solvent system used for thin layer chromatography. VI. Furthering of the uniform design method].

In this paper, we optimized the solvent systems of sulfa drugs and five traditional Chinese medicines for thin layer chromatography by means of uniform design method. The optimal system for the eleven sulfa drugs is benzene-n-butanol-n-hexane (5.71:2.86:1.43). The optimal systems for Mu Xiang and Jiu Li Xiang are all absolute chloroform. The optimal systems for Liang Mian Zhen and San Cha Ku are all acetonitrile-ethyl ether-methyl chloride-cyclohexane (0.05:0.3:0.1:0.55). The optimal system for Jin Yin Hua is ethyl acetate-methyl chloride-formic acid (1:1:1). The method has been born out to be theoretical, simple and practical. In our opinion, it is an effective systematic method.

Chromatography, Thin Layer↗

PubMed1992

[The status of biological risk factors and the optimality concept in diagnosis of early childhood developmental disorders].

In a prospective study the psychomotor development up to the end of the second year of life of 409 preterm and term newborn infants was examined in order to identify which optimality score might be associated with disturbances of normal childlike development. Significant connections between 24 and 55 risk factors and the mortality could be demonstrated, but only 3 factors (sex, apgar, acidosis) exert influence on psychomotor development. The risk loading of the collective was high, not one of the children showed an optimal score. Decreased patients possessed a stronger reduced optimality than survivors. The optimality concept is not suitable for the prediction of later disturbed development of children, because the items are unspecific. The marker of hypoxia, the erythrocytic-density-test, as well as the neuron-specific enolase showed better diagnostic values than the optimality concept.

Brain Damage, Chronic↗

PubMed1992

[Computer-aided prediction of optimal composition of multicomponent mobile phase in high performance liquid chromatography].

This paper proposed a systematic optimizing method for the composition of multicomponent mobile phase in high performance liquid chromatography. A new chromatographic response function (CRF) has been constructed according to the fundamental retention equation and rule of peak width at half-height, and the optimal composition of multicomponent mobile phase can be automatically predicted by a computer with CRF. This paper improved the known complex method, therefore, the optimal mobile phase composition in the global area may be found by means of this modified complex method. The optimal separation conditions of four vitamins and three nitrophenols were determined by use of the optimizing method reported in this paper. The results predicted by the computer were verified by the experimental data obtained in HPLC using ternary mobile phase.

Chromatography, High Pressure Liquid↗

PubMed2003

Optimization of the treatment of piggery wastes in water hyacinth ponds.

This work investigates the optimal management of water hyacinth ponds for the improvement of piggery waste treatment. The optimal harvesting strategy for the water hyacinth was studied using a single mathematical model. The water hyacinth optimal harvesting problem was formulated as an optimal control problem that was solved by application of Pontryagin's Maximum Principle. The optimization of the water hyacinth control in the pond indicates that the plant density should be reduced whenever it reaches half of the maximum capacity for growth. Two experimental systems were used to validate the mathematical model, one in real scale and the other in pilot scale. The results demonstrated the feasibility of the proposed harvesting strategy. For example, a comparison of the total nitrogen removal in the different pilot ponds confirmed the modeling results, in that the performance of the pond maintained with 50% water hyacinth cover was better than the others.

Animals↗

PubMed1992

Salivary levels of lactobacilli, buffer capacity and salivary flow rate related to caries activity among adults in communities with optimal and low water fluoride concentrations.

In several human studies, scientists have sought to elucidate the connection between caries activity, high levels of lactobacilli, low buffer capacity and a low salivary flow rate, separately or in combinations. The aims of the study were to investigate if there was a difference in caries activity among adults in optimal versus low fluoride areas. It was further investigated if this difference was related to high lactobacilli levels, low buffer capacity and low salivary flow rate, separately or in combination. Finally, it was analysed if the lactobacilli levels were lower in an area with optimal fluoride water concentration. The study is based on clinical examinations of 30-40 year olds who all their lives had drunk water with a fluoride concentration representative for the community. 260 individuals living in the optimal fluoride area and 236 from the low fluoride area are included in the study. The results show a caries activity significantly lower among those in the optimal fluoride area. It is also shown that these differences can not be explained by differences in lactobacilli levels, buffer capacity and salivary flow, neither separately nor in combination. The fluoride concentration in the drinking water is wholly decisive. No difference in lactobacilli levels between optimal and low fluoride areas were demonstrable in this study.

Adult↗

PubMed1992

Modelling the optimal control of cyclical leg movements induced by functional electrical stimulation.

An optimal control strategy for FES-induced cyclical leg movements in paraplegics is proposed. The control of the cyclical movement of a freely swinging leg is considered as an example. Quadriceps and the flexion withdrawal reflex are stimulated in order to generate a cyclical movement, of which the forward swing resembles the swing phase of gait. Optimal stimulation patterns are determined on the basis of an optimization criterion and a dynamic model of the system. The criterion is based on desired movement parameters and a minimal duration of the stimulation bursts. The movement parameters should ensure the generation of the desired cyclical movement: a desired hip angle range, sufficient foot clearance during the forward swing and knee extension at the beginning of the backward swing. Minimal duration of the stimulation bursts is assumed to yield minimal fatigue. A dynamic model, describing the dynamics of the neural system, the muscles and the leg, was constructed and its parameters identified on the basis of preliminary experiments and literature. Optimal timing of the quadriceps and flexion reflex stimulation bursts was determined by means of computer simulation. These simulations predicted that the flexion reflex should be stimulated in a short burst approximately 150 ms before the start of the forward swing. The quadriceps should be stimulated approximately starting 200 ms before the end of the forward swing in order to ensure knee extension at the beginning of the backward swing. The duration of one cycle of the movement was between 1300 and 1500 ms in these simulations. These results predict that the movement specified by the functional objectives can be realised using only two channels of stimulation. On the basis of the optimal timing, an adaptive control strategy can be designed, which varies the stimulation burst width when muscles fatigue.

Biomechanical Phenomena↗

PubMed2004

[The problem of optimization in cardiology].

Optimization is understood as choice of the best version out of the competitive decisions. The strategy and tactics of prevention is presented from this point of view. Optimization of diagnostic investigations is viewed from the positions of continuum with quantitative assessment of results. Characteristics of loads and heart activity, as recommendations suggest, should be in agreement in stress tests. Optimization of dynamic investigations of biochemical markers is described on the model of acute coronary syndrome. Optimization of therapy is based on the determination of criteria of optimum. This statement is illustrated by the example of antihypertensive therapy. Optimization of pharmacotherapy must envisage the preservation of favorable effect of protective natural mechanisms in the form of autoregulation and adaptation to intermittent ischemia (preconditioning).

Cardiology↗

PubMed2004

[Optimization of microemulsion containing vinpocetine and its physicochemical properties].

AIM: To prepare the microemulsion of vinpocetine in order to increase solubility and its in vitro transdermal delivery by using appropriate proportion of oil, surfactant (S), cosurfactant (CoS) and water. The formulation of proportion was optimized. The physicochemical properties and the skin irritation of the microemulsion was studied. METHODS: Pseudo-tertiary phase diagrams were prepared to obtain the concentration ratio of components of the microemulsion. Using simplex lattice method, the formulation of microemulsion was optimized and the physicochemical properties including pH, viscosity, refractive index, conductivity and particle size distribution were examined. The MTT method was applied to test the skin irritation of the microemulsion on the Hacat cell. RESULTS: The diagrams showed that the areas of O/W microemulsion increased with the increasing ratio of surfactant to cosurfactant (S/CoS). The predicted values from simplex lattice system were close to that of the experiment. The property of optimized microemulsion showed to be stable behavior and not irritant to Hacat cell. CONCLUSION: The drug solubility and in vitro perscutaneous permeation flux of the optimized microemulsion was improved significantly and the irritation study showed that optimized microemulsion was safe as an ideal transdermal delivery system.

Administration, Cutaneous↗

PubMed2004

[Mechanism analysis of optimized model of conversion from farmland to forestland in the hill-gully sub-region of Loess Plateau].

Conversion from Farmland to Forestland Program (CFF) is one of the six great ecological forest programs in China. This study covered the CFF model area of the hilly-gully sub-region of loess plateau, and introduced system dynamics and other latest theories and methodologies. Based on the analysis of five modules including that of the site observation of field stations and extensive investigations, and over 10000 original data obtained in the fields of natural science, social science and economics, the operational mechanism of the optimized model was studied. The optimized operational models integrated maximized ecological, economic and social benefits, while sustainability concepts were proposed for typical CFF sites: The Pinus tabulaeformis + Platycladus orientalis + Zanthoxylum spp. + Robinia pseudoacacia model at the eroded flat ridges of the middle reaches of the Yellow River. The result showed that the ecological, economic and social benefits of the optimized model reflected by main indexes were the best or better, and in the other models, either individual one was the best or others were not. From the viewpoint of comprehensive comparison of three great benefits, the optimized model was most excellent, and had eminent difference comparing to other ones through F test. The relationship between ecological and social benefit was eminent positive correlative. Social benefit was the same with economical one at some degrees. The relationship between ecological and economical benefit was more complicated. On the whole, they were positive correlative, but the economical benefit was not the greatest when the ecological one was the greatest. In general, from the viewpoint of largest comprehensive benefit, the three great benefits were not all the best, indicating that the combination of the modules must be reasonable. In order to achieve the ultimate goal of CFF, we must choose the optimized combination of ecological, economical and social benefits, and can't only pursue any one maximum of three great benefits.

China↗

PubMed2005

Optimizing injected dose in clinical PET by accurately modeling the counting-rate response functions specific to individual patient scans.

UNLABELLED: To optimize the injected dose of radiopharmaceutical in PET, one needs to know its relationship to some metric of data quality for individual patient scans, such as noise-equivalent counting rate (NECR). In this paper, we show how one may accurately model the clinical NECR response corresponding to specific patient scans much as if a counting-rate test had been performed on each patient. We apply this technique to patient data and show how it can lead to improved clinical scanning protocols. METHODS: True and random coincidence rates expressed as functions of an appropriate measurable system parameter such as the detector single-event rate have functional forms that are largely independent of the object being scanned. Thus, reference true and random response functions may be scaled directly to the specific counting rates measured on a clinical scan, thereby yielding a curve of NECR versus injected dose. We have applied this technique to 2 groups of 163 clinical (18)F-FDG scans each. One of the groups was obtained on a lutetium oxyorthosilicate PET/CT scanner with conventional front-end electronics, and the other was obtained on a lutetium oxyorthosilicate PET/CT scanner with a new digital data processing system (Pico-3D). RESULTS: At 90%-95% of maximum signal-to-noise ratio (SNR), the mean optimal dose for a 60-min uptake period ranged from 366 to 717 MBq depending on the electronics and randoms processing method. There was only a slight (1 MBq/kg) dependence of optimal dose on patient weight but a larger dependence on position in the body. Pico-3D electronics improved optimal data SNR by 35% for a 70-kg person, but in both cases NECR fell rapidly with increasing weight (1.4%/kg). For an equivalent data SNR, a 120-kg person would have to be scanned 2.3 times longer than a 60-kg person. Over this range of weight, the mean scatter fraction increased by 12% whereas the ratio of mean randoms to trues increased by 48%. CONCLUSION: The methodology developed here allows one to directly estimate the optimal dose to inject for specific clinical scans and permits a detailed analysis of the sources of noise in PET data and of their variation with parameters such as patient weight.

Computer Simulation↗

PubMed2006

Optimization of atrioventricular delay by surface electrocardiography during dual chamber pacing.

BACKGROUND: Nominal atrioventricular (AV) interval in dual chamber pacemaker (DDD) is not the best AV delay in the majority of patients with atrioventricular block. To find a simple method for optimizing AV delay adjustment, we assessed surface electrocardiography (ECG) for optimizing AV delay during dual chamber pacing. METHODS: DDD pacemakers were implanted in 46 patients with complete, or almost complete, AV block. Optimal AV delay was achieved by programming an additional delay of 100 ms, to the width of intrinsic P wave or to the interval between pacing spike to the end of P wave on surface ECG. Left ventricular (LV) end diastolic and end systolic volumes, ejection fraction and diastolic parameters were measured by Doppler echocardiography during both nominal and optimal AV delay pacing. RESULTS: Compared to nominal AV delay setting, LV end diastolic volume increased [to (53.2 +/- 11.3) ml from (50.2 +/- 10.2) ml, P < 0.05], end systolic volume decreased [to (26.1 +/- 9.0) ml from (27.9 +/- 8.2) ml, P < 0.05] during adjusted AV delay pacing, resulting in an increase in LV ejection fraction [to (68.2 +/- 5.3)% from (64.5 +/- 4.3)%, P < 0.05]. LV diastolic filling and isovolumic relaxation time were not significantly changed. CONCLUSION: Optimization of AV delay by surface ECG is a simple method to improve LV systolic function during dual chamber pacing.

Adult↗

PubMed2006

[Culture condition optimization of engineered E. coli BL21/pET-11c/hIL-2-mGM-CSF].

OBJECTIVE: To optimize the culture condition of engineered E.coli to improve its expression efficiency of hIL-2-mGM-CSF protein. METHODS: According to an orthogonal Latin square experiment design, the effects of the culture medium, temperature and IPTG concentration at different levels on the efficiency of the engineered E. coli were evaluated for its expression of hIL-2-mGM-CSF protein. The results of SDS-PAGE were analyzed with software and the culture conditions derived from the experimental results were tested in independent cultures. The optimal culture condition was used in three large-scale cultures and the results were compared with that of routine cultures. RESULTS: The cultures with TH broth yielded higher relative expression quantity of the target protein than those with 2 x YT and LB medium. Compared with the induction temperature at 37 degrees C, induction at 42 degrees C significantly improved the expression efficiency of the target protein. IPTG at the concentration as low as 0.3 mmol/L produced better effect than 1.0 mmol/L IPTG. Statistical analysis suggested that the optimized culture conditions could obviously improve the expression efficiency of the target protein. Large scale cultures with the optimized culture condition resulted in a 5-fold improvement of the relative expression quantity of the protein, which accounted for over 29% of total bacterial protein. CONCLUSION: The optimized culture condition of the engineered E. coli can remarkably increase the expression efficiency of hIL-2-mGM-CSF, which may facilitate the subsequent purification and functional study of the protein.

Culture Media↗

PubMed2006

[A preliminary study of beam weight optimization of intensity-modulated radiation therapy with genetic algorithm].

UNLABELLED: To study the method for dose calculation and beam weight optimization of intensity-modulated radiation therapy (IMRT). METHODS: The IMRT dose calculation model based on two-dimensional convolution was constructed, the program of dose calculation and beam weight optimization with genetic algorithm was written with Visual c#.Net, and the optimization results were analyzed. RESULTS: Genetic algorithm optimization of beam weights can produce highly conformal dose distributions within a clinically acceptable computation time. CONCLUSION: Genetic algorithm is valid and efficient in IMRT beam weight optimization, which may facilitate IMRT treatment planning.

Algorithms↗

PubMed2006

Sensory pleasure optimizes muscular work.

PURPOSE: To determine how an individual optimizes muscular work. SOURCE: Several previous investigations by the author that explored the hedonicity of various sensations aroused during work and compared the results with the subjects' performances. PRINCIPAL FINDINGS: When a subject is given the task to climb 300 m elevation on a treadmill, at various combinations of speed and slope, if slope is imposed and speed self adjusted, or speed imposed and slope self adjusted, the subject spontaneously climbs the 300 m in a constant time. Thus, the subject worked his body at a constant power (work x duration(-1)). Thus, a person optimizes his own behaviour spontaneously. Systematic exploration of the hedonic dimension (pleasure/displeasure) of sensory experience from various parts of the body, over a broad range of muscular work showed that pleasure is experienced when a useful stimulus, as judged from the point of view of optimization of physiological function, is present. Displeasure occurs when a noxious stimulus is present. When a stimulus is neither useful nor noxious, the sensation aroused is indifferent. The relationship of hedonicity with physiology is so tight that these properties of sensation can be used as a tool to explore the body's physiological integrity. Hedonicity is also aroused during muscular exercise. Experimental evidence will be provided to demonstrate that the pleasures/displeasures of sensory inputs from the chest and from muscles are the signals that are the source of optimal muscular work. CONCLUSION: The experimental results confirmed that pleasure is the common currency that is used by the brain to compare sensations aroused by muscular work from various parts of the body. Maximization of the algeabraic sum of these hedonic sensations optimizes the resulting muscular performance.

Exercise↗

PubMedDate not supplied

Optimization of techniques in screening CT of the sinuses.

The number of screening examinations of the sinuses performed with CT has markedly increased owing to the widespread and increasing use of endoscopic sinonasal surgery. We reviewed scans from 500 patients who had screening CT examinations of the sinuses for preendoscopic evaluation of inflammatory sinonasal disease to better define an optimal imaging protocol. Three aspects of direct coronal imaging of the paranasal sinuses were investigated: (1) preparation of the patient prior to the examination; (2) technical factors of the CT study, including positioning of the patient, optimal coronal angle, slice thickness, and CT exposure factors; and (3) data display. Our experience indicates that pretreatment of the patient with maximal medical therapy enables the best preendoscopic definition of anatomy, disease pattern, and nonreversible disease component for the treating surgeon. CT technical factors are optimized with scanning in the prone position with thin (3-mm) sections obtained through the anterior paranasal sinuses. This allows optimal visualization of the ostiomeatal unit. The remaining posterior portions of the sinuses are adequately imaged with thicker slices (5 mm). The coronal scan angle used is less critical. Exposure factors (mAs) can be reduced dramatically without image compromise. Data display is optimized when the bone algorithm is used to acquire the data and with image display at intermediate window center and width level. Use of the techniques outlined in this article results in a cost-effective yet diagnostic scan of the sinuses with decreased radiation exposure to the patient.

Cost-Benefit Analysis↗

PubMed1979

[Distribution of obstetrical and postnatal risk-factors in 400 randomly selected newborns. A study using Prechtl's concept of optimal conditions (author's transl)].

The distribution of obstetrical and postnatal risk-factors in a population of 400 newborns was investigated. For documentation, an extended list of Prechtl's list of optimal obstetric conditions was used. The newborns had been selected randomly from two populations, born 1972 in two different hospitals (County hospital, University hospital). The reduction of optimal conditions was calculated by percentiles. It was found that the number -3 (of 52 items, representing full optimal conditions) defined the 10th percentile of the population; number -5 the median, and number -10 the 90th percentile. In addition, percentiles were calculated regarding the history of the mother and the history of the infant respectively. Using the distribution of reduced obstetrical and postnatal optimal conditions allows to compare the history of a single newborn or the histories of a population of newborns with defined problems. Newborns with rather low negative numbers of reduced optimal conditions are at lower risk regarding their psychomotor development wheras newborns with high negative numbers carry a much higher irsk in this respect.

Birth Injuries↗

PubMed1979

Response-surface co-optimization of reaction conditions in clinical chemical methods.

We describe the theory and applications of the response-surface approach to simultaneous optimization (co-optimization of multiple interdependent variables. The co-optimization experiments are designed according to a selected response-surface model. Computer-assisted analysis includes fitting the data to the model, testing the resulting fit for statistical validity, and plotting contour maps of the model for simple interpretation. Co-optimizations of the reaction parameters of three methods--creatine kinase, lipase, and aspartate aminotransfrease--are discussed to illustrate the application of the approach. In contrast to the commonly used optimization strategies in which each factor is varied in turn while the others are kept constant, the response-surface approach allows study of several responses (reaction rates, sensitivities) and effects (linear, curvature, interaction) at the same time. It also allows determination of accurate optima, which is necessary for the formulation of analytically reliable clinical methods.

Aspartate Aminotransferases↗