Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “parameter identification”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,117 records · Page 62Linked to original sources
PubMed1979

Separation of standard opiates and their analysis in pharmaceutical and illicit preparations by paired-ion reverse-phase high-pressure liquid chromatography.

The separation of standard opiates in a mixture and their analysis in clandestine and pharmaceutical preparations were accomplished by PIC on a micro-Bondapak C18 column. The identification of the opiates was based on two parameters: retention times and the ratios of absorbance peaks recorded at 254 and 280 nm. No prior clean-up procedure of samples was required for analysis by this method. Baseline separation of drug components in clandestine and in pharmaceutical preparations made this method suitable for their quantitation.

Chromatography, High Pressure Liquid↗
PubMed1980

Identifiability in tracer experiments.

The paper deals with structural identifiability of compartmental systems via tracer experiments, i.e., with the problem of stating a priori whether a planned input-output identification experiment allows the estimation of all unknown parameters of a compartmental system. Compartmental models and tracer experiments are briefly reviewed. A formal definition of structural identifiability is given on the basis of system theory concepts. A structural identifiability test is presented and necessary conditions are given which can be tested on the compartmental diagram, without writing the symbolic expressions of the input-output relationships. Three examples are presented; the first two show how to practically employ the suggested rules, while the third one refers to a pharmacokinetic model.

Cell Compartmentation↗
PubMed1995

[Contemporary possibilities of prognosis in myelodysplastic syndromes].

Myelodysplastic syndromes (MDS) comprise a heterogenous group of closely related, acquired stem cell disorders. Various patterns of clinical evolution have been observed in patients with different subtypes according to the FAB (French-American-British) criteria. The marked differences in clinical outcome among MDS patients have encouraged us to search the alternative variables for predicting leukemic transformation and survival. During the past 10 years different prognostic scoring systems based on age combined with blood and bone marrow parameters have been described. This has enabled the identification of patients with better and worse prognosis among different MDS types. Additionally, studies of cytogenic patterns in MDS patients and widespread availability of bone marrow histological specimens extended the possibility of prognosis in this disease. Similarly, the in vitro culture results of hematopoietic cells using growth and differentiation factors have given very promising results. The high prevalence of RAS mutation in patients with MDS has been defined, but its clinical usefulness is under discussion.

Bone Marrow↗
PubMed1976

[On-line analysis of the exercise electrocardiogram].

A programme of on-line automated analysis of ECG exercise graphs relative to the CB5 derivation is described. The various operations may be subdivided into the following phases: 1) performance; 2) mean complex; 3) identification; 4) calculation and print-out of parameters; 5) filing. Automatic analysis of exercise ECG's eliminating artifacts present in graphs and obtaining parameters that are not respectively assessable, facilitates the development of rigorously objective diagnostic guidelines. The filing of indices on magnetic tape opens the way to subsequent statistical analysis of extreme usefulness in testing extensive populations.

Coronary Disease↗
PubMed1995

Evaluation of criteria for uvulopalatoplasty (UPP) patient selection using acoustic analysis of oronasal respiration (SNAP testing).

This study was designed to evaluate the acoustic parameters of sleeping oronasal respiration as determined by the SNAP system, to identify those that might aid in identifying appropriate candidates for uvulopalatoplasty (UPP). Eighteen UPP patients who completed preoperative and postoperative SNAP testing and assessment interviews were analyzed. Significant multiparametric changes subsequent to UPP were identified. These parameters were then correlated with subjective outcomes and predictive parameters were defined that may aid in the identification of patients who would be the most appropriate candidates for UPP. Predictive correlation with relief of snoring was noted when the relative loudness of velum-like snoring was greater than 12 dB and the snoring distribution was dominated by low-frequency (velum-like) snoring (> 85%). Objective and more accurate UPP candidate selection may be possible using SNAP testing.

Adult↗
PubMed2000

Bayesian identification of a population compartmental model of C-peptide kinetics.

When models are used to measure or predict physiological variables and parameters in a given individual, the experiments needed are often complex and costly. A valuable solution for improving their cost effectiveness is represented by population models. A widely used population model in insulin secretion studies is the one proposed by Van Cauter et al. (Diabetes 41:368-377, 1992), which determines the parameters of the two compartment model of C-peptide kinetics in a given individual from the knowledge of his/her age, sex, body surface area, and health condition (i.e., normal, obese, diabetic). This population model was identified from the data of a large training set (more than 200 subjects) via a deterministic approach. This approach, while sound in terms of providing a point estimate of C-peptide kinetic parameters in a given individual, does not provide a measure of their precision. In this paper, by employing the same training set of Van Cauter et al., we show that the identification of the population model into a Bayesian framework (by using Markov chain Monte Carlo) allows, at the individual level, the estimation of point values of the C-peptide kinetic parameters together with their precision. A successful application of the methodology is illustrated in the estimation of C-peptide kinetic parameters of seven subjects (not belonging to the training set used for the identification of the population model) for which reference values were available thanks to an independent identification experiment.

Adult↗
PubMed2006

On the risk of false positive identification using multiple ion monitoring in qualitative mass spectrometry: large-scale intercomparisons with a comprehensive mass spectral library.

Analysts involved in qualitative mass spectrometry have long debated the minimum data requirements for demonstrating that signals from an unknown sample are identical to those from a known compound. Often this process is carried out by comparing a few selected ions acquired by multiple ion monitoring (MIM), with due allowance for expected variability in response. In a few past experiments with electron-ionization mass spectrometry (EI-MS), the number of ions selected and the allowable variability in relative abundance were tested by comparing one spectrum against a library of mass spectra, where library spectra served to represent potential false positive signals in an analysis. We extended these experiments by carrying out large-scale intercomparisons between thousands of spectra and a library of one hundred thousand EI mass spectra. The results were analyzed to gain insights into the identification confidence associated with various numbers of selected ions. A new parameter was investigated for the first time, to take into account that a library spectrum with a different base peak than the search spectrum may still cause a false positive identification. The influence of peak correlation among the specific ions in all the library mass spectra was also studied. Our computations showed that (1) false positive identifications can result from similar compounds, or low-abundance peaks in unrelated compounds if the method calls for detection at very low levels; (2) a MIM method's identification confidence improves in a roughly continuous manner as more ions are monitored, about one order of magnitude for each additional ion selected; (3) full scan spectra still represent the best alternative, if instrument sensitivity is adequate. The use of large scale intercomparisons with a comprehensive library is the only way to provide direct evidence in support of these conclusions, which otherwise depend on the judgment and experience of individual analysts. There are implications for residue chemists who would rely on standardized confirmation criteria to assess the validity of a given confirmatory method. For example, standardized confirmation criteria should not be used in the absence of interference testing and rational selection of diagnostic ions.

Journal Article↗
PubMed1999

Identification of the Constitutive Behaviour of Dental Composite Cements During Curing.

This paper is concerned with the qualitative and quantitative description of the constitutive behaviour of dental composites during the curing process. Both generalized Kelvin- and Maxwell-models are studied and the parameters characterizing these models are determined by the means of an identification procedure based on the matching of model calculations to experimental data. This procedure is illustrated by means of an example. It is found that the Maxwell-model fits the experimental data better than the Kelvin Model.

Journal Article↗
PubMed2006

Microsatellite markers for standardized genetic management of captive colonies of rhesus macaques (Macaca mulatta).

To preserve genetic variability and minimize genetic subdivision among captive Macaca mulatta at each of the U.S. National Institutes of Health (NIH)-sponsored regional research colonies, the genetic structure of each colony must be characterized. To compare population genetic and demographic parameters across colonies and generations, one standard panel of highly informative genetic markers is required. We assembled a core marker set of four multiplex polymerase chain reaction (PCR) panels comprising 15 autosomal short tandem repeat (STR) loci with high information content selected from existing panels of well-characterized markers that are currently used for parentage assessment and genetic management of rhesus macaques. We then assessed the effectiveness of these loci for providing high probabilities of individual identification and parentage resolution, and for estimating population genetic parameters that are useful for genetic management.

Animal Husbandry↗
PubMed2000

Correlation between some discrimination functions and hemoglobin E.

The most widely used discriminant functions and red cell indices for differential diagnosis of thalassemia traits from iron deficiency anemia were evaluated for their abilities to identify HbE-containing blood samples. The functions were as follows: F1 = 0.01 x MCH x (MCV)2; F2 = RDW x MCH x (MCV)2/Hb x 100; F3 = MCV/RBC; and F4 = MCH/RBC. Other red cell parameters including RDW, hemoglobin content, mean cell volume, mean cell hemoglobin as well as red cell counts, were also evaluated to distinguish HbE from the normal population. Hemoglobin electrophoresis was used as a confirmatory test. The results showed that F1, F2 and F3 as well as other red cell parameters of HbE-containing samples were different from those of HbA2A-containing red cells although there was no statistical significance. However, F4 and MCHC showed no difference between the two groups. It can be concluded from the present study that identification of hemoglobin E especially the heterozygous form by using parameters from an electronic cell counter is not easy. Discriminant functions and red cell indicies might be used as an initial diagnosis. But confirmation is needed in all cases. Applying the MCV of 80 fl will miss 5 per cent of hemoglobin E carrier but will not miss the homozygous form.

Anemia, Iron-Deficiency↗
PubMed1978

[An automated study of EEG: a method of detection of non-stationary points].

The purpose of this paper is to present an automatic method of signal analysis. To help physicians in their diagnostics, this method is implemented on a minicomputer in order to detect non-stationary points in electroencephalograms. The signal is modelled with an autoregressive filter. The parameters of this filter are adapted at each step. Identification gives the best model in the sense of a cost function representing the mean square error of noise, which is estimated during the optimisation time-window. The cost function is expressed by a quadratic formula. This allows the use of a fast algorithm, the 'conjugate gradient method'. An original statistical test is developed to detect non-stationary points in the signal. The performance of this method is tested with artificial data to determine the sensitivity of method parameters. Detection using real data is presented.

Computers↗
PubMed1993

Masking disrupts recovery of location information.

In two experiments, we tested subjects' ability to localize a letter in a character string with identification controlled by varying the delay of a mask, dimming the display, or deleting some of the dots used to define the letters on the cathode-ray screen. The first experiment involved two tasks. In the first task, subjects indicated whether or not a letter named verbally had been present in an eight-letter target string. In the second task, they localized a letter named verbally in the target string; the target string was presented by using display parameters shown in the first task to hold character identification between 70% and 75% correct. In the second experiment, we tallied errors in a partial-report bar-probe study after equating performance across the manipulations of display quality. Masking disrupted subjects' ability to recover location information more than either a manipulation of stimulus luminance or a manipulation of its visual form.

Female↗
PubMed1994

[Microbiologic criteria of the choice of antibiotic for antibiotic prophylaxis in surgery].

The choice of an antibiotic for antimicrobial prophylaxis is based on microbiological, pharmacokinetic, chemical and pharmacodynamic parameters. The knowledge of the bacterial flora allows the identification of bacteria which could be responsible for postsurgical infections. These floras are complex and their equilibrium can be modified by various factors, such as hospitalization, co-existing disease, medico-surgical procedure, administration of antibiotics, which cause the selection of the so-called hospital-bacteria feared by therapists. The infection will develop according to the quantity of bacteria that have been introduced and to their virulence, which is often altered by local factors, especially the biomaterials. The knowledge of pharmacodynamic parameters such as bactericidal activity, postantibiotic effect, activity on virulence factors (bacterial adhesion), allows the refinement of the choice of the antibiotic and the optimization of its posology.

Anti-Bacterial Agents↗
PubMed2004

A computational method for assessing peptide- identification reliability in tandem mass spectrometry analysis with SEQUEST.

High-throughput protein identification in mass spectrometry is predominantly achieved by first identifying tryptic peptides by a database search and then by combining the peptide hits for protein identification. One of the popular tools used for the database search is SEQUEST. Peptide identification is carried out by selecting SEQUEST hits above a specified threshold, the value of which is typically chosen empirically in an attempt to separate true identifications from false ones. These SEQUEST scores are not normalized with respect to the composition, length and other parameters of the peptides. Furthermore, there is no rigorous reliability estimate assigned to the protein identifications derived from these scores. Hence, the interpretation of SEQUEST hits generally requires human involvement, making it difficult to scale up the identification process for genome-scale applications. To overcome these limitations, we have developed a method, which combines a neural network and a statistical model, for normalizing SEQUEST scores, and also for providing a reliability estimate for each SEQUEST hit. This method improves the sensitivity and specificity of peptide identification compared to the standard filtering procedure used in the SEQUEST package, and provides a basis for estimating the reliability of protein identifications.

Algorithms↗
PubMed1988

The role of mathematical models in the study of HIV transmission and the epidemiology of AIDS.

The role of mathematical models in the study of human immunodeficiency virus (HIV) transmission, the epidemiology and demographic impact of acquired immune deficiency syndrome (AIDS), and the course of infection within an individual is reviewed. Attention is focused on the part models can play in short-term prediction, parameter estimation, the interpretation of observed patterns, and the identification of areas in which knowledge is inadequate. Methods for short-term predictions, over 1-3 years, have proved reliable and can take account of distributed delays in the interval between reporting and diagnosis. Parametric and nonparametric methods have been developed for estimating summary statistics (e.g., means) for the distributed incubation period of AIDS. Current estimates, based on cohort or transfusion-associated AIDS cases, lie in the range of 7-10 years. Transmission models for longer-term prediction are less reliable at present given the many uncertainties concerning key epidemiological parameters. Theoretical studies highlight the need for quantitative data on temporal changes in the distribution of rates of sexual partner change and fluctuations in viral abundance in serum, secretions, and excretions (i.e., infectiousness) throughout the long and variable incubation period of the disease.

Acquired Immunodeficiency Syndrome↗
PubMed1996

[Quality assessment in anesthesia].

Quality assessment (assurance/improvement) is the set of methods used to measure and improve the delivered care and the department's performance against pre-established criteria or standards. The four stages of the self-maintained quality assessment cycle are: problem identification, problem analysis, problem correction and evaluation of corrective actions. Quality assessment is a measurable entity for which it is necessary to define and calibrate measurement parameters (indicators) from available data gathered from the hospital anaesthesia environment. Problem identification comes from the accumulation of indicators. There are four types of quality indicators: structure, process, outcome and sentinel indicators. The latter signal a quality defect, are independent of outcomes, are easier to analyse by statistical methods and closely related to processes and main targets of quality improvement. The three types of methods to analyse the problems (indicators) are: peer review, quantitative methods and risks management techniques. Peer review is performed by qualified anaesthesiologists. To improve its validity, the review process should be explicited and conclusions based on standards of practice and literature references. The quantitative methods are statistical analyses applied to the collected data and presented in a graphic format (histogram, Pareto diagram, control charts). The risks management techniques include: a) critical incident analysis establishing an objective relationship between a 'critical' event and the associated human behaviours; b) system accident analysis, based on the fact that accidents continue to occur despite safety systems and sophisticated technologies, checks of all the process components leading to the impredictable outcome and not just the human factors; c) cause-effect diagrams facilitate the problem analysis in reducing its causes to four fundamental components (persons, regulations, equipment, process). Definition and implementation of corrective measures, based on the findings of the two previous stages, are the third step of the evaluation cycle. The Hawthorne effect is an outcome improvement, before the implementation of any corrective actions. Verification of the implemented actions is the final and mandatory step closing the evaluation cycle.

Anesthesia↗
PubMed2004

Trace labeling of proteins with stable isotopes to identify fragments in complex mixtures.

We describe a novel nonradioactive protein-labeling technique that permits mass spectrometric identification of fragments of labeled proteins. Proteins are labeled by modulating their content of carbon-13 and labeled fragments identified from the distinctive isotope pattern observed on MALDI-TOF mass spectrometry. We show that carbon-13 enrichment to just 2.3% of total carbon (about twice the natural abundance of 1.1%) is sufficient for all fragments to be distinguishable from fragments of natural carbon-13-content proteins. Distinguishing labeled fragments is easily accomplished by visual inspection of spectra, but importantly, we show that labeled fragments can also be identified by computer analysis of spectra using novel parameters we have derived. The technique is demonstrated for identification of fragments of carbon-13-enriched glutathione transferase within a complex mixture of unlabeled peptides by visual and computer analysis of MALDI-TOF mass spectra, but it could be developed to mass spectrometrically identify and characterize fragments of labeled proteins recovered from biological systems.

Automation↗
PubMed2026

Application of musculoskeletal ultrasound in postoperative rehabilitation assessment and monitoring after rotator cuff repair: A systematic review.

BACKGROUND: The development of rehabilitation protocols after rotator cuff repair has long lacked objective benchmarks. Traditional time‑based regimens are limited by considerable inter‑individual variability and an increased risk of re‑tear. Musculoskeletal ultrasound allows dynamic assessment of tendon healing and muscle morphology, yet evidence for directly linking its use to rehabilitation decisions remains scarce. OBJECTIVE: To systematically synthesize the evidence on the use of musculoskeletal ultrasound monitoring to inform rehabilitation decision‑making after rotator cuff repair. METHODS: Following the Preferred Reporting Items for Systematic Reviews and Meta‑Analyses (PRISMA) guidelines, we searched PubMed, China National Knowledge Infrastructure (CNKI), and Wanfang Data from January 2020 to April 2026. Original studies were included if they involved patients who had undergone rotator cuff repair, used musculoskeletal ultrasound (including gray‑scale ultrasound, elastography, etc.) to evaluate the rotator cuff tendons or shoulder muscles, and reported at least one parameter related to rehabilitation decision-making or functional outcomes. RESULTS: Eleven studies were included. Shear wave velocity (SWV), cross‑sectional area (CSA), and echo intensity (EI) were the most frequently reported ultrasound parameters. Available evidence indicated that SWV increased progressively after surgery, with an overall increase of approximately 22% to 25% from one week to 12 months postoperatively. This dynamic trajectory may serve as a reference baseline for judging rehabilitation progress. An abnormally elevated SWV in the early postoperative period was associated with an increased risk of re‑tear, suggesting that a more conservative rehabilitation strategy should be adopted. Tendon stiffness measured at 12 weeks after surgery independently predicted long‑term return to sport. Regarding muscle parameters, changes in CSA and EI were positively correlated with shoulder function scores, and the combination of these two parameters effectively identified patients with rehabilitation bottlenecks. CONCLUSION: Musculoskeletal ultrasound parameters are associated with the initiation of active movement, adjustment of exercise load, prediction of return‑to‑sport prognosis, and identification of retear risk. Among these, SWV shows particular promise as an objective monitoring parameter for supporting rehabilitation assessment after rotator cuff repair. Future randomized controlled trials are needed to determine whether ultrasound-informed assessment can improve rehabilitation outcomes compared with traditional time-based regimens, and to establish standardized measurement protocols and clinically applicable reference values. Key findings of this review are summarized in S1 File.

Humans↗