Temperature dependence of photoluminescence in porous silicon and its interpretation using the porous-cluster model.
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Journal Article↗
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Results for “Model interpretability”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
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Geometrical interpretation of the semimicroscopic algebraic cluster model.
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Journal Article↗
Acoustical description of syllabic nuclei: an interpretation in terms of a dynamic model of articulation.
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Acoustics↗
Pressure-volume data of cat lung interpreted by a plastoelastic, linear viscoelastic model.
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Elasticity↗
Dynamic stochastic synapses as computational units.
In most neural network models, synapses are treated as static weights that change only with the slow time scales of learning. It is well known, however, that synapses are highly dynamic and show use-dependent plasticity over a wide range of time scales. Moreover, synaptic transmission is an inherently stochastic process: a spike arriving at a presynaptic terminal triggers the release of a vesicle of neurotransmitter from a release site with a probability that can be much less than one. We consider a simple model for dynamic stochastic synapses that can easily be integrated into common models for networks of integrate-and-fire neurons (spiking neurons). The parameters of this model have direct interpretations in terms of synaptic physiology. We investigate the consequences of the model for computing with individual spikes and demonstrate through rigorous theoretical results that the computational power of the network is increased through the use of dynamic synapses.
Action Potentials↗
Pharmacokinetic analysis of blood level data interpreted by a two-compartment model.
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Mathematics↗
Performance evaluation of SBR treatment for nitrogen removal from tannery wastewater.
Performance of SBR treatment for nitrogen removal from tannery is evaluated for a wide range of wastewater temperature between 7 and 30 degrees C. A pilot-scale SBR unit fed with plain-settled wastewater is operated on site for this purpose. Effective nitrogen removal is sustained by adjustment of the sludge age from 28 to 5 days. Concentration profiles of nitrogen compounds within a selected complete SBR cycle during the steady state operation at different wastewater temperatures and sludge ages are evaluated by model simulation. System performance is also interpreted in terms of modeling and stoichiometric calculation. Additional nitrate loss was observed during aerobic period when the aeration intensity was reduced by the factor of 50%.
Industrial Waste↗
[Collaborated admission to a surgical department].
BACKGROUND: The medical case record is an important tool for securing high quality in treatment and care of patients. Efficient and accurate documentation of diagnostic and therapeutic procedures, patient information etc. is crucial. MATERIAL AND METHODS: We have prospectively studied how time and patient satisfaction are influenced when nurse and doctor together ("combined model") take the patient's medical history, perform a clinical examination, and inform the patient, compared to separate history-taking by nurse and doctor ("separate model"). RESULTS: The mean nurse time per patient increased from 17 min in the separate model to 21 min in the combined model (p = 0.01). Corresponding time use by the doctor was 26 min and 21 min (p = 0.04), and for the patient 43 min and 23 min (p < 0.001). Patients reported the two models to be comparable in quality. INTERPRETATION: The "combined registration model" secures high quality of the medical case record, respects the patient's time, and signals professional collaboration to the patient.
Adult↗
[The visco-elastic behavior of the respiratory system during mechanical ventilation. Interpretation with the aid of a model].
The purpose of this review is to present an approach to the visco-elastic properties of the respiratory system in the mechanically ventilated patient through the method of occlusion of the airways at a constant inspiratory flow rate. The ideas of airways resistance, tissue resistance, static and dynamic elastance are defined from the theoretical point of view and also from the point of view of the occlusion method. A large part is given to the bicompartmental model describing the visco-elastic properties of the lung and of the thoracic wall. Recently carried out experimental studies both in healthy man and in disease have given results which seem to confirm the predictions made by this model. According to this system the lungs may be represented as a homogenous whole surrounded by visco-elastic components.
Airway Resistance↗
[Open-mindedness in interpreting the report: comments on the model meeting with local inhabitants].
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Community Participation↗
Mathematical aspects of source modeling.
This paper reviews the properties of the major source models which are used in the analysis of observed bioelectric signals in general, and of evoked potentials in particular. The interpretation of such models demands the solution of an associated inverse problem. Emphasis is laid on the possibility of imposing such constraints on the model which render stable inverse solutions and yet allow a physiological interpretation. The nature of this paper is tutorial.
Bioelectric Energy Sources↗
Advantages and limitations of metaanalytic regressions of clinical trials data.
OBJECTIVE: To focus on methodology of metaregression and demonstrate to clinicians, through 2 published examples, some strengths and limitations. EXAMPLE 1 METHODS: Metaanalysis of data from 20 years of randomized trials of lidocaine prophylaxis in preventing primary ventricular fibrillation (VF) in myocardial infarction used separate data for control and active-treatment groups to model the risk of VF as a function of year of publication and other study characteristics. EXAMPLE 1 RESULTS: Collinearity between pairs of predictor variables can lead to difficulty in interpreting logistic regression models. EXAMPLE 2 METHODS: Metaanalysis of data from 7 trials (323 patients) measured treatment effect of immunosuppressive therapy for acute Crohn's disease by response-rate difference (RD, experimental minus control group). EXAMPLE 2 RESULTS: Weighted least-squares regression models of the RD suggested an association between RD and various study characteristics, but collinearity again led to difficulty in interpretation of multiple regression results. DISCUSSION: Warning signs of colinearity include: large pairwise correlations between predictor variables, large changes in coefficients caused by the addition or deletion of other variables, and extremely large SEs for coefficients. Suggestions for coping with collinearity include: removing redundant variables from the model, reducing reliance on interpretation of coefficients for confounding variables, forming one or more summary variables, centering the data, collecting more data, and using more sophisticated regression methods. CONCLUSIONS: Metaanalysis can explore variations in as well as summarize results of randomized trials. Although metaregression has advantages, study characteristics are often strongly associated with each other, leading to collinearity.
Acute Disease↗
Machine learning-based prediction of unplanned readmission and construction of an online calculator for elderly patients with mild ischemic stroke.
OBJECTIVE: To screen for independent risk factors for unplanned readmission in elderly patients with mild ischemic stroke, and to construct and validate an online risk prediction calculator based on an interpretable machine learning model, thereby providing a promising practical tool for accurate clinical assessment of 30‑day all‑cause unplanned readmission risk in this population. METHODS: A prospective cohort study was conducted, including 1050 patients aged ≥ 60 years with mild ischemic stroke admitted between August 2023 and September 2024. Participants were randomly divided into a training set (840 cases) and a test set (210 cases) at a ratio of 8:2. Risk factors were screened by univariate analysis and multivariable Logistic regression. Four machine learning models, namely LightGBM, XGBoost, Random Forest, and K‑Nearest Neighbors (KNN), were developed and their performance was evaluated using AUC, accuracy, sensitivity, and specificity as metrics. The SHAP framework was used for interpretability analysis, and an online calculator was subsequently developed based on the optimal model. RESULTS: Univariate analysis showed significant differences (P < 0.05) in 13 factors including age, smoking, AIP, TyG index, HALP score, etc. Multivariable Logistic regression identified age (OR = 9.752), smoking (OR = 5.171), AIP (OR = 6.691), TyG index (OR = 4.393), HALP score (OR = 2.831), and ≥ 2 comorbidities (OR = 3.664) as independent risk factors. All four machine learning models demonstrated good predictive performance. Based on a comprehensive evaluation of multiple metrics and computational efficiency, the LightGBM model exhibited the best predictive performance (AUC = 0.884, accuracy = 0.829, sensitivity = 0.812, specificity = 0.875). SHAP analysis showed that age, AIP, TyG index, smoking, and HALP score were key predictors. An online calculator developed based on this model enables individualized risk predictions. CONCLUSION: Key risk factors associated with 30‑day unplanned readmission in elderly patients with mild ischemic stroke were identified. The LightGBM model demonstrated high predictive accuracy, and together with the interpretability analysis and online calculator, offers a practical tool to support clinical risk assessment. However, this tool requires future external validation.
Humans↗
Quantitative structure-activity models. Some conditions for application and statistical interpretation.
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Chemical Phenomena↗
Reduced-rank hazard regression for modelling non-proportional hazards.
The Cox proportional hazards model is the most common method to analyse survival data. However, the proportional hazards assumption might not hold. The natural extension of the Cox model is to introduce time-varying effects of the covariates. For some covariates such as (surgical)treatment non-proportionality could be expected beforehand. For some other covariates the non-proportionality only becomes apparent if the follow-up is long enough. It is often observed that all covariates show similar decaying effects over time. Such behaviour could be explained by the popular (gamma-) frailty model. However, the (marginal) effects of covariates in frailty models are not easy to interpret. In this paper we propose the reduced-rank model for time-varying effects of covariates. Starting point is a Cox model with p covariates and time-varying effects modelled by q time functions (constant included), leading to a pxq structure matrix that contains the regression coefficients for all covariate by time function interactions. By reducing the rank of this structure matrix a whole range of models is introduced, from the very flexible full-rank model (identical to a Cox model with time-varying effects) to the very rigid rank one model that mimics the structure of a gamma-frailty model, but is easier to interpret. We illustrate these models with an application to ovarian cancer patients.
Biometry↗
A Quantitative Simulation Model for H-Amino Acid Cotransport To Interpret the Effects of Amino Acids on Membrane Potential and Extracellular pH.
The H(+) cotransport of neutral and acidic amino acids induces transient depolarizations of oat coleoptile (Avena sativa L., var Victory) plasma membranes. The depolarizations, which are completed within 1 or 2 minutes, are followed by repolarizations that are nearly completed within another 2 or 3 minutes. Cysteine induced a two-phased alkalinization of the tissue free space during the electrical changes. The first phase was a rapid, linear increase in pH that coincided with the depolarization; the second phase was a slower, also linear, increase in pH that coincided with the repolarization. Reacidification did not occur until cysteine was withdrawn. Five other acidic, basic, and neutral amino acids also induced persistent alkalinization of the free space.The notable features of these measurements are that free-space pH was measured more directly than previously, that pH changes corresponded in time to the electrical potential changes, and that reacidification of the free space did not occur. The latter observation indicates that net H(+) efflux did not occur during repolarization and that the repolarizing current was carried by some other ion. We propose that repolarization could have depended upon depolarization-induced changes in passive K(+) fluxes combined with an enhanced H(+) extrusion that increased until it equaled, but did not exceed, the enhanced influx of H(+).In support of the feasibility of our hypothesis, we present a quantitative simulation model for cotransport. The simulation model also provides an interpretation of the unique electrical effects of histidine and the basic amino acids. In addition, the model focuses attention upon the difficulties of interpreting H(+)-anion cotransport.
Journal Article↗
A milestone in ribosomal crystallography: the construction of preliminary electron density maps at intermediate resolution.
Preliminary electron density maps of the large and the small ribosomal particles from halophilic and thermophilic sources, phased by the isomorphous replacement method, have been constructed at intermediate resolution. These maps contain features comparable in size with what is expected for the corresponding particles, and their packing arrangements are in accord with the schemes obtained by ab-initio procedures as well as with the motifs observed in thin sections of the crystals by electron microscopy. To phase higher resolution data, procedures are being developed for derivatization by specific labeling of the ribosomal particles at selected locations with rather small and dense clusters. Potential binding sites are being inserted either by site directed mutagenesis or by chemical modifications to facilitate cluster binding on the surface of the halophilic large and the thermophilic small ribosomal particles, which yield the crystals diffracting to highest resolution (2.9 and 7.3 A (1 A = 0.1 nm), respectively). For this purpose, the surface of these ribosomal particles is being characterized and procedures are being developed for quantitative detachment of selected ribosomal proteins and for their incorporation into core particles. The genes of these proteins are being cloned, sequenced, mutated to introduce reactive side groups, mainly cysteines, and overexpressed. In parallel, two in situ small and stable complexes were isolated from the halophilic ribosome. Procedures for their crystal production in large quantities are currently being developed. Models, reconstructed at low resolution from crystalline arrays of ribosomes and their large subunits, are being used for initial low-resolution phasing of the X-ray amplitudes. The interpretation of these models stimulated the design and the crystallization of complexes mimicking defined functional states of a higher quality than those obtained for isolated ribosomes. These models also inspired modelling experiments according to results of functional studies, performed elsewhere, focusing on the progression of nascent proteins.
Base Sequence↗
Skin blood flow evaluated by the laser speckle method and the transcutaneous oxygen tension: interpretation of the dynamics using a simple model.
Spontaneous fluctuations of skin blood flow were measured by the laser speckle method in a time interval of 1024s. The frequency spectra of the resulting signal (blood flow parameter B) were calculated using the fast Fourier transformation. The mean spectrum was obtained from at least six single measurements on different days in the range 0.02 Hz-0.2 Hz. For five of six subjects no peak exists in the mean spectrum because it can be approximated by an exponential function with a mean frequency ranging between 0.05 Hz and 0.13 Hz (cycle length 7.7s - 20s). The dynamics of skin blood flow during ischaemia and reactive hyperaemia were simultaneously characterized by the blood flow parameter B and the transcutaneous oxygen tension p (24 measurements in 12 subjects). A simple theoretical model including a feedback control system for the stabilization of the tissue oxygen concentration is proposed. It provides an interpretation for the features of the dynamics of blood flow parameter B and transcutaneous oxygen tension p and their mutual relations, namely: (1) The increase in blood flow parameter B following the occlusion is determined by the arterial flow resistance. (2) The half-time for the decline of the blood flow parameter B from the peak of the reactive hyperaemia response to the final steady-state value and the existence of the spontaneous fluctuations of B indicate the active control of blood flow by the oxygen concentration in the tissue. (3) The large time constants of the oxygen tension equilibration during ischaemia and reactive hyperaemia originate from the capacity of the tissue to store oxygen. (4) The cycle length of the fluctuations (5s-50s) corresponds surprisingly well with the time constants for the decline of the blood flow parameter B from the peak to the steady-state (12.5s-42.5s).
Adult↗