Medicaid plans tap into the power of predictive modeling.
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Cost Control↗
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Results for “model predictive control”
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Modeling photoheterotrophic growth kinetics of Rhodospirillum rubrum inrectangular photobioreactors.
Based on a previously established model for radiant light transfer in photobioreactors (PBR), taking into account absorption and scattering of light, a new knowledge model for coupling radiant light energy available and local growth kinetics in PBRs for the photoheterotrophic bacteria Rhodospirillum rubrum is discussed. A revised method is presented for the calculation of the absorption and scattering coefficients. The specific characteristics of the electron-transfer chains in such microorganisms leads to definition of three different metabolic zones in the PBR, explaining the behavior of mean kinetics observed in a wide range of incident light fluxes. The model is validated in rectangular PBRs for five different carbon sources and proved robust and fully predictive. This approach can be considered for simulation and model-based predictive control of PBRs cultivating photoheterotrophic microorganisms.
Absorption↗
Social support, locus of control, and parenting in three low-income groups of mothers: black teenagers, black adults, and white adults.
Mother's social support, their instrumental use of extended family members and of professionals for help, and their sense of personal control were examined as predictors of parenting skill in 3 groups of low-income women. Separate regression models were generated for black adult mothers, white adult mothers, and black teen mothers, all of whom had at least 1 infant. Black teen and white adult mothers who sought help with child-rearing problems from extended family members were more skillful parents. Among white mothers, use of professionals for help with child-rearing problems and mothers' sense of internal control were also significant predictors. Black adult mothers' parenting skill was predicted only by locus of control. These prediction models suggest that in 2 of the groups, social ties to significant others were the linkages through which child-rearing information flowed to affect parenting behavior.
Adolescent↗
Complex predictive eye pursuit in monkey: a model system for cerebellar studies of skilled movement.
Smooth pursuit eye movements provide a good model system for cerebellar studies of complex motor control in monkeys. First, the pursuit system exhibits predictive control along complex trajectories and this control improves with training. Second, the flocculus/paraflocculus region of the cerebellum appears to generate this control. Lesions impair pursuit and neural activity patterns are closely related to eye motion during complex pursuit. Importantly, neural responses lead eye motion during predictive pursuit and lag eye motion during non-predictable target motions that require visual control. The idea that flocculus/paraflocculus predictive control is non-visual is also supported by a lack of correlation between neural activity and retinal image motion during pursuit. Third, biologically accurate neural network models of the flocculus/paraflocculus allow the exploration and testing of pursuit mechanisms. Our current model can generate predictive control without visual input in a manner that is compatible with the extensive experimental data available for this cerebellar system. Similar types of non-visual cerebellar control are likely to facilitate the wide range of other skilled movements that are observed.
Action Potentials↗
Geographic information systems and the distribution of Schistosoma mansoni in the Nile delta.
New computer-based sensor technology and geographic methods have led to emerging interest in use of satellite environmental assessment tools for design of disease control programs, especially for those that are vector borne. The long-range goal of work reported here by John Malone and colleagues on behalf of this Egyptian Ministry of Health-USAID Schistosomiasis Research Project team (Box 1) is to utilize data from sensor systems on board earth-observing satellites to develop more-sensitive disease-prediction and -control models. If successful, methods developed may provide a potentially vital capability for use by disease control program managers, particularly in less-developed countries, where mapping resources are not well advanced. Longer term, broader basic questions on the interaction of environment and disease in anticipation of predicted global climate change may be addressed. These studies focused on the lower Nile river basin of Egypt. The specific objective was to link data on environmental requirements for propagation and transmission of schistosomiasis with parameters measurable from space.
Journal Article↗
Integrated approaches in urban storm drainage: where do we stand?
Integrated approaches to urban storm-water drainage management are being increasingly advocated as necessary for advancing more sustainable and holistic management of urban water environments. In this paper, the status of integrated approaches in the management of urban storm-water discharges to receiving waterways is summarized. The starting point of the paper is with the recent scientific contributions, revealing that integration is being pursued and implemented predominantly at two conceptual levels. These include 1) integrating the technical system with the receiving waterway environment, and 2) considering the interaction and influence of the human system with the technical system through processes such as stakeholder and public participation. Additionally, it is argued that the evolving shift towards the implementation of water-quality-based strategies advances the need for further development and application of integrated models and approaches. The cases of online physically based models for predictive control and integrated source control and public participation are presented as examples of such ongoing developments in pursuit of integrated urban storm-water management.
Community Participation↗
Evaluation of glucose controllers in virtual environment: methodology and sample application.
OBJECTIVE: Adaptive systems to deliver medical treatment in humans are safety-critical systems and require particular care in both the testing and the evaluation phase, which are time-consuming, costly, and confounded by ethical issues. The objective of the present work is to develop a methodology to test glucose controllers of an artificial pancreas in a simulated (virtual) environment. MATERIAL AND METHODS: A virtual environment comprising a model of the carbohydrate metabolism and models of the insulin pump and the glucose sensor is employed to simulate individual glucose excursions in subjects with type 1 diabetes. The performance of the control algorithm within the virtual environment is evaluated by considering treatment and operational scenarios. RESULTS: The developed methodology includes two dimensions: testing in relation to specific life style conditions, i.e. fasting, post-prandial, and life style (metabolic) disturbances; and testing in relation to various operating conditions, i.e. expected operating conditions, adverse operating conditions, and system failure. We define safety and efficacy criteria and describe the measures to be taken prior to clinical testing. The use of the methodology is exemplified by tuning and evaluating a model predictive glucose controller being developed for a wearable artificial pancreas focused on fasting conditions. CONCLUSION: Our methodology to test glucose controllers in a virtual environment is instrumental in anticipating the results of real clinical tests for different physiological conditions and for different operating conditions. The thorough testing in the virtual environment reduces costs and speeds up the development process.
Algorithms↗
Interaction between Gregg's phenomenon and coronary flow control: a model study.
Coronary perfusion pressure, Pp, affects coronary arterial resistance, Ra, (autoregulation) as well as myocardial oxygen consumption, MVO2 (Gregg's phenomenon). The interaction between the effects of Pp and MVO2 on coronary flow control was investigated using a coronary flow control model. Model analysis predicts that response of the pressure-flow ratio, p/q(t), following a change in Pp depends on the sensitivity of Ra to a change in tissue oxygen concentration (tone sensitivity) and on the sensitivity of MVO2 to a change in capillary pressure (Gregg's sensitivity). At high tone sensitivity Gregg's effect is small, whereas at high Gregg's sensitivity autoregulation is attenuated. In experiments glibenclamide decelerated the p/q(t) in response to a pressure step by a factor of four. However, the proposed model demonstrates that this is compatible with a reduction in rate of change of Ra by a factor of ten. This is due to the interaction of negative and positive feedback gains in the model. Model analysis demonstrates that autoregulation and Gregg's phenomenon compete with each other in controlling coronary flow.
Animals↗
Short-time behavior of mixed diffusion-barrier controlled adsorption.
This paper focuses on the short-time adsorption kinetics of nonionic surfactants onto water/air surfaces, analyzed in the context of the mixed diffusion-barrier controlled adsorption modeling framework. Specifically, we reconcile the apparent contradiction between theoretical prediction and experimental observations on the adsorption kinetics mechanism at short times: while the mixed diffusion-barrier controlled model predicts a barrier-controlled adsorption, as well as the impossibility of a diffusion-controlled adsorption at asymptotic short times, the short-time experimental dynamic surface tension (DST) behavior of many nonionic surfactants has been interpreted to result from diffusion-controlled adsorption at asymptotic short times. This is because the short-time experimental DST of these surfactants displays a t variation, which is considered as a fingerprint for the existence of diffusion-controlled adsorption, based on the short-time asymptotic behavior of the diffusion-controlled adsorption model. As a result of this interpretation, the fundamental physical nature of the energy barrier has been proposed to be associated with high surfactant surface concentrations. In this paper, we derive a new nonasymptotic short-time formalism of the mixed diffusion-barrier controlled model to describe surfactant adsorption onto a spherical pendant-bubble surface, including determining the ranges of time and surfactant surface concentration values where the short-time formalism is applicable. Based on this formalism, we find that one can expect to observe an apparent t variation of the DST at short times even for the mixed diffusion-barrier controlled adsorption model. We analyze the consequence of this finding by re-evaluating the existing notions of the energy barrier. We conclude that the energy barrier is associated with the adsorption of a single surfactant molecule onto a clean surface.
Journal Article↗
S 16924 ((R)-2-[1-[2-(2,3-dihydro-benzo[1,4] dioxin-5-yloxy)-ethyl]-pyrrolidin-3yl]-1-(4-fluoro-phenyl)-ethanone), a novel, potential antipsychotic with marked serotonin (5-HT)1A agonist properties: II. Functional profile in comparison to clozapine and haloperidol.
S 16924 antagonized locomotion provoked by dizocilpine and cocaine, reduced conditioned avoidance responses and blocked climbing elicited by apomorphine, models predictive of control of the positive symptoms of schizophrenia: its median inhibitory dose (ID)50 was 0.96 mg/kg, s.c. vs. 1.91 for clozapine and 0.05 for haloperidol. Rotation elicited in unilateral, substantia nigra-lesioned rats by the D1 agonist, SKF 38393, and by the D2 agonist, quinpirole, was blocked equipotently by S 16924 (0.8 and 1. 7) and clozapine (0.6 and 2.0), whereas haloperidol preferentially blocked quinpirole (0.02) vs. SKF 38393 (1.8). S 16924 more potently inhibited the head-twitches elicited by 1-(2, 5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) and the locomotion provoked by phencyclidine than it inhibited the locomotion elicited by amphetamine (ID50s = 0.15 and 0.02 vs. 2.4). Clozapine showed a similar preference (0.04 and 0.07 vs. 8.6), but not haloperidol (0. 07 and 0.08 vs. 0.04). The discriminative stimulus (DS) properties of DOI were also blocked by S 16924 (ID50 = 0.17) and clozapine (0. 05) but not by haloperidol (>0.16). S 16924 fully (100%) generalized [effective dose (ED)50 = 0.7] to a clozapine DS and clozapine (0.23) fully generalized to a S 16924 DS whereas haloperidol (>/=0.08) only partially generalized (</=50%) to their DS in each case. Power spectra analysis of electroencephalograms from frontal cortex showed that both S 16924 (2.0) and clozapine (5.0) reinforced frequencies in the 7 to 8 Hz range whereas haloperidol (0.5) preferentially reinforced frequencies in the 10 to 14 Hz range. In a model of perturbation of cognitive-attentional function, significant latent inhibition was obtained with S 16924 (0.08) and clozapine (0.16), but not haloperidol (0.0063 and 0.04): higher doses of S 16924 (2.5), clozapine (5.0) and haloperidol (0.1) all blocked disruption of latent inhibition by amphetamine (1.5). Catalepsy was provoked by haloperidol (0.04-0.63) but not by S 16924 (>/=80.0) or clozapine (>/=80.0). Further, S 16924 (ID50 = 3.2) and clozapine (5.5) inhibited induction of catalepsy by haloperidol. This action of S 16924 was abolished by the 5-HT1A receptor antagonist, WAY 100,635 (0.16), which less markedly attenuated the anticataleptic action of clozapine. Further, although gnawing elicited by methylphenidate was inhibited by S 16924 (ID50 = 8.4), clozapine (19.6) and haloperidol (0.04), only the action of S 16924 was blocked by WAY 100,635 (0.16). Haloperidol potently (0.01-0.16, approximately 24-fold) increased prolactin levels whereas they were less markedly affected by S 16924 (2.5-40.0, 4-fold) and clozapine (10.0-40.0, 3-fold). Clozapine displayed high affinity at cloned, human, muscarinic (M1) and native, histamine (H1) receptors (Kis = 4.6 and 5.4 nM, respectively), whereas S 16924 (>1000 and 158) and haloperidol (>1000 and 453) displayed low affinity. In conclusion, S 16924 displays a profile of activity in diverse models of potential antipsychotic and extrapyramidal properties similar to that of clozapine and different to that of haloperidol. In particular, reflecting its partial agonist actions at 5-HT1A receptors, S 16924 inhibits rather than induces catalepsy in rats. However, in contrast to clozapine, S 16924 displays only low affinity for muscarinic and histaminic receptors.
Amphetamines↗
Nonstationary properties of the saccadic system: new constraints on models of saccadic control.
1. We tested the predictions of two models of the saccadic burst generator by electrically stimulating sites in primate superior colliculus (SC) immediately following visually guided movements. 2. The amplitude and direction of stimulated saccades depend systematically on the amplitude and direction of preceding visually guided saccades, and that effect decays exponentially with a time constant of approximately 45 ms. The saccadic system, then, displays an amplitude-dependent non-stationarity that follows an exponential time course during the intersaccadic interval (ISI). 3. These results are consistent with a variant of the eye displacement model proposed by Jurgens et al. but not with Robinson's classic model of the burst generator. Moreover, since all models of saccadic control must predict either stationary or nonstationary behavior during the ISI, these results provide a powerful new constraint on those models. 4. Finally, the success of the displacement model in accounting for our data suggests a new explanation for the results of colliding saccade experiments.
Animals↗
The shape of the force-elbow angle relationship for maximal voluntary contractions and sub-maximal electrically induced contractions in human elbow flexors.
The force-length relationship is a basic property of skeletal muscle. Knowledge of this relationship is necessary for most analyses of human movement, and in simulation models predicting movement control strategies. Studies on animal muscles have shown that force-length relationships for sub-maximal contractions are not related through a simple scaling procedure to the relationship for maximal contractions. Furthermore, potentiation might produce a shift of sub-maximal relative to maximal force-length relationships. In this study, we tested the hypothesis that human force-elbow angle relationships for sub-maximal unpotentiated contractions are shifted to larger elbow angles (i.e. larger muscle lengths) compared to the relationship for maximal voluntary contractions (MVC), and that this shift is reduced, or even abolished, for sub-maximal potentiated contractions. Force-elbow angle relationships (48-160 degrees) were obtained from healthy subjects (n=13). At each of nine tested elbow angles, the test set consisted of a single twitch (ST(pre)) and a doublet twitch (DT(pre)) stimulation of m. biceps brachii, followed by an MVC, followed by another single twitch (ST(post)) and a doublet twitch (DT(post)) stimulation. The single and doublet twitches induced sub-maximal contractions. The force-elbow angle relationships for the pre-MVC (unpotentiated) twitch contractions were shifted to larger angles compared to those obtained for MVC. The force-elbow angle relationships for the post-MVC (potentiated) twitch contractions were shifted to smaller angles compared to those obtained for the unpotentiated twitch contractions. These results support the idea that the shift to larger muscle lengths for the sub-maximal, unpotentiated force-length relationships relative to the relationship for maximal contractions may be caused by a length-dependent Ca(2+) sensitivity that may be offset, at least in part, by potentiation.
Adaptation, Physiological↗
Adsorption and desorption of chemotherapeutic drugs from a magnetically targeted carrier (MTC).
Magnetically targeted carriers (MTCs) are composite microparticles made from metallic iron and activated carbon. Particles, loaded with doxorubicin in the pharmacy (MTC-DOX), are infused intra-arterially through the artery feeding the tumor. With the aid of an externally positioned permanent dipole magnet, they can be localized and retained within a tumor mass. MTC-DOX is currently in use in a Phase I/II clinical study as a delivery vehicle for doxorubicin in primary hepatocellular carcinoma. The adsorption and desorption of doxorubicin, mitomycin C, camptothecin, methotrexate, verapamil and 9AC onto MTCs have been analyzed. Each of these chemotherapeutic agents has a different mechanism of action, suggesting that some benefit may be derived from combined delivery to a tumor using MTCs and magnetic targeting. Each drug displays different behavior with respect to adsorption and desorption. However, this behavior can be described for each drug with a non-linear thermodynamic model. The thermodynamic model predicts a controlled release rate by adjusting a number of parameters, including initial drug loading concentrations. This is confirmed with in vitro extraction experiments using human plasma as the extraction medium.
Adsorption↗
A model for human skin impedance during surface functional neuromuscular stimulation.
A new mathematical model for the bulk electrical impedance of human skin is presented. In particular this model describes the impedance of skin during surface functional neuromuscular stimulation (FNS) with square stimulation pulses. Experimental data are presented that illustrate the nonlinear dynamic properties of human skin during current and voltage controlled stimulation. Model predictions are compared to experimental data, measured under both constant voltage and constant current transcutaneous stimulation. It is found that this model captures a variety of nonlinear time-varying effects observed in the skin impedance when stimulating with either protocol. This model may be used as part of large neuromusculoskeletal models or in the more accurate modeling of transcutaneous FNS, which is currently the most common clinical implementation of FNS.
Electric Impedance↗
A note on model-free regression capabilities of fuzzy systems.
Nonparametric estimation capabilities of fuzzy systems in stochastic environments are analyzed in this paper. By using ideas from sieve estimation, increasing sequences of fuzzy rule-based systems capable of consistently estimating arbitrary regression surfaces are constructed. Results include least squares learning of a mapping perturbed by additive random noise in a static-regression context. L1 (i.e., least absolute deviation) estimation is also studied, and the consistency of fuzzy rule-based sieve estimators for L1-optimal regression surfaces is shown, thus giving additional theoretical support to the robust filtering capabilities of fuzzy systems and their adequacy for modeling, prediction, and control of systems affected by impulsive noise.
Journal Article↗
Methamphetamine dependence: medication development efforts based on the dual deficit model of stimulant addiction.
Converging lines of evidence indicate that withdrawal from prolonged exposure to stimulants and alcohol results in synaptic deficits of both dopamine (DA) and serotonin (5-HT). According to the dual deficit model proposed by the authors, DA dysfunction during cocaine or alcohol withdrawal underlies anhedonia and psychomotor retardation, whereas 5-HT dysfunction gives rise to depressed mood, obsessional thoughts, and lack of impulse control. This model predicts that pharmacotherapies which correct only one of the two neurochemical deficits will not be effective. On the other hand, pharmacotherapies which "correct" both of the proposed DA and 5-HT abnormalities should be effective in treating stimulant and alcohol dependence. This paper reviews two approaches, based on the dual deficit model, taken by our laboratory to develop medications to treat stimulant abuse.
Animals↗
Clinical profiles and outcomes of acute type B aortic dissection in the current era: lessons from the International Registry of Aortic Dissection (IRAD).
BACKGROUND: Clinical profiles and outcomes of patients with acute type B aortic dissection have not been evaluated in the current era. METHODS AND RESULTS: Accordingly, we analyzed 384 patients (65+/-13 years, males 71%) with acute type B aortic dissection enrolled in the International Registry of Acute Aortic Dissection (IRAD). A majority of patients had hypertension and presented with acute chest/back pain. Only one-half showed abnormal findings on chest radiograph, and almost all patients had computerized tomography (CT), transesophageal echocardiography, magnetic resonance imaging (MRI), and/or aortogram to confirm the diagnosis. In-hospital mortality was 13% with most deaths occurring within the first week. Factors associated with increased in-hospital mortality on univariate analysis were hypotension/shock, widened mediastinum, periaortic hematoma, excessively dilated aorta (>or=6 cm), in-hospital complications of coma/altered consciousness, mesenteric/limb ischemia, acute renal failure, and surgical management (all P<0.05). A risk prediction model with control for age and gender showed hypotension/shock (odds ratio [OR] 23.8, P<0.0001), absence of chest/back pain on presentation (OR 3.5, P=0.01), and branch vessel involvement (OR 2.9, P=0.02), collectively named 'the deadly triad' to be independent predictors of in-hospital death. CONCLUSIONS: Our study provides insight into current-day profiles and outcomes of acute type B aortic dissection. Factors associated with increased in-hospital mortality ("the deadly triad") should be identified and taken into consideration for risk stratification and decision-making.
Aged↗
Sensorimotor memory for fingertip forces: evidence for a task-independent motor memory.
When repetitively lifting an object with randomly varying mechanical properties, the fingertip forces reflect the previous lift. We examined the specificity of this "sensorimotor memory" by observing the effects of an isolated pinch on the subsequent lift of a known object. In this case, the pinch force was unrelated to the fingertip forces necessary to grip the object efficiently. The peak grip force used to lift the test object (4 N weight) depended on the preceding task. Compared with repetitively lifting the 4 N test object, the peak grip force was 2 N greater when a lift of the same object was preceded by a lift in which a hidden mass was attached to the object to increase the weight to 8 N. This 2 N increase in grip force also occurred when subjects lifted the 4 N test object after pinching a force transducer with a force of 8 N. Thus, similar grip forces were stored in sensorimotor memory for both tasks, and reflected subjects' use of 7.9 +/- 1.1 N to lift the 8 N object. Similar effects occurred when the preceding pinch or lift was performed with the opposite hand. The peak lift force was unaffected by the isolated pinch, suggesting that a generalized increase in fingertip and limb forces did not occur. We conclude that the sensorimotor memory is not specific for lifting an object. It is doubtful that this particular memory stores the physical properties of objects or reflects a forward internal model for predictively controlling fingertip forces.
Acceleration↗