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At least 757 records · Page 42Linked to original sources
PubMed1987

Analysis of the clinical findings used to diagnose coliform mastitis in dairy cows, and comparison to a prediction model.

Logistic regression was used to analyze the clinical findings (attributes) which predicted coliform mastitis in 113 dairy cattle, 36 of which had coliforms cultured from milk. Weakness of the cow, swelling of the udder, decreased body temperature and watery consistency of the milk were selected for the model. An analysis was then done to find the attributes which clinicians used when predicting that a cow would have a coliform cultured. Clinicians appeared to use water consistency of the milk, shivering, firmness of the udder, pulse rate, elevated body temperature, and respiratory rate. In a final analysis the clinicians' predictions were forced into the model to determine which attributes might be used by clinicians to increase diagnostic accuracy. Inclusion of weakness of the cow, swelling of the udder, decreased temperature of the cow, and duration of mastitis of less than 24 hours increased accuracy over clinical prediction alone. Accuracy of cowside diagnosis might be increased if more attention were paid to these attributes when making a diagnosis of coliform mastitis.

Animals↗
PubMed2007

Individual and combined effects of ph and lactic acid concentration on Listeria innocua inactivation: development of a predictive model and assessment of experimental variability.

In food technology, organic acids (e.g., lactic acid, acetic acid, and citric acid) are popular preservatives. The purpose of this study was to separate the individual effects of the influencing factors pH and undissociated lactic acid on Listeria innocua inactivation. Therefore, the inactivation process was investigated under controlled, initial conditions of pH (pH0) and undissociated lactic acid ([LaH]0). The resulting inactivation curves consisted of a (sometimes negligible) shoulder period followed by a descent phase. In a few cases, a tailing phase was observed. Depending on the conditions, the descent phase contained one or two log-linear parts or had a convex or concave shape. In addition, the inactivation process was characterized by a certain variability, dependent on the severity of the conditions. Furthermore, in the neighborhood of the growth/no growth interface sometimes contradictory observations occurred. Overall, the individual effects of the influencing factors pH and undissociated lactic acid could clearly be distinguished and were also apparent based on fluorescence microscopy. Appropriate model types were developed and enabled prediction of which conditions of pH0 and [LaH]0 are necessary to obtain a predetermined inactivation (number of decimal reductions) within a predetermined time range.

Food Preservatives↗
PubMed2004

The mortality index for neonatal transportation score: a new mortality prediction model for retrieved neonates.

OBJECTIVE: To develop a mortality prediction score for retrieved neonates based on the information given at the first telephone contact with a retrieval service. METHODS: Data from the New South Wales Newborn and Pediatric Emergency Transport Service database were examined. Analysis was performed with the results for 2504 infants (median gestational age: 36 weeks; range: 24-43 weeks) who were <72 hours of age at the time of referral and whose outcome (neonatal death or survival) was known. The study population was divided randomly into 2 halves, the derivation and validation cohorts. Univariate analysis was performed to identify variables in the derivation cohort related to neonatal death. The variables were entered into a multivariate logistic regression analysis with neonatal death as the outcome. Receiver operator characteristic (ROC) curves were constructed with the regression model and data from the derivation cohort and then the validation cohort. The results were used to generate an integer-based score, the Mortality Index for Neonatal Transportation (MINT) score. ROC curves were constructed to assess the ability of the MINT score to predict perinatal and neonatal death. RESULTS: A 7-variable (Apgar score at 1 minute, birth weight, presence of a congenital anomaly, and infant's age, pH, arterial partial pressure of oxygen, and heart rate at the time of the call) model was constructed that generated areas under ROC curves of 0.82 and 0.83 for the derivation and validation cohorts, respectively. The 7 variables were then used to generate the MINT score, which gave areas under ROC curves of 0.80 for both neonatal and perinatal death. CONCLUSION: Data collected at the first telephone contact by the referring hospital with a regionalized transport service can identify neonates at the greatest risk of dying.

Analysis of Variance↗
PubMed2005

Sorption kinetics of strontium in porous hydrous ferric oxide aggregates II. Comparison of experimental results and model predictions.

In a previous paper, we introduced the Donnan diffusion model to describe cation diffusion into microporous solids with variably charged surfaces, such as hydrous ferric oxides (HFO). Here, we present experiments investigating slow diffusion and sorption of strontium by HFO aggregates with well-characterized porosity. Adsorption of protons and strontium at the HFO surface was evaluated by acid-base titration and batch adsorption experiments with dispersed HFO. The experimental data were fitted with a 1-pK basic Stern model including surface ion pair formation of Na(+) and NO(3)(-) and charge distribution for Sr surface complexes. Sorption-diffusion experiments were conducted in flow-through columns at controlled flow rates and at two different pH values, pH 4 and 7. Wet HFO aggregates, which were synthesized using a freezing and thawing method, were packed into chromatographic columns, pre-equilibrated to reach a constant pH, and then Sr breakthrough curves for adsorption and desorption of Sr were recorded. Strong retardation of Sr indicated that diffusion was sufficiently fast in a fraction of pores, so that sorption sites in these pores were rapidly accessible. Based on the analysis of NaNO(3) breakthrough curves, this rapidly accessible pore fraction was estimated to be 37% of the total aggregate pore volume at pH 4.0 and 72% at pH 7.0, respectively. Taking this into account, the Donnan diffusion model gave a good description of the experimental Sr breakthrough curves. Cation exclusion was correctly predicted at pH 4.0. At pH 7, the strong tailing of Sr breakthrough curves due to Sr diffusion into the smallest pores was very well simulated. The Donnan diffusion model proved adequate for pore sizes between approximately 2 and 5 nm, depending on pH and ionic strength. This category of pores was dominant in the HFO aggregates used in this work.

Journal Article↗
PubMed1995

Predictive modelling of growth of Escherichia coli O157:H7: the effects of temperature, pH and sodium chloride.

The growth responses of Escherichia coli O157:H7 as affected by NaCl concentration, pH value and storage temperature were studied in laboratory medium. Growth curves at concentrations of NaCl in the range 0.5-6.5% (w/v), pH values in the range 4.0-7.0 and storage temperatures in the range 10-30 degrees C were fitted using the Gompertz routine and the derived parameters modelled. Growth curves could then be regenerated for any set of conditions within the matrix studied and values for growth rate, generation time, lag time and time to 1000-fold increase predicted. The model was validated against data from the literature and was found to give realistic estimates for generation time in media and a range of foods including meat and poultry, milk, cheese and tempeh. All predictions were consistently 'fail-safe'.

Culture Media↗
PubMed1994

Predictive modelling of growth of Yersinia enterocolitica: the effects of temperature, pH and sodium chloride.

The growth responses of Yersinia enterocolitica as affected by NaCl concentration, pH value and storage temperature were studied in laboratory medium. Growth curves at concentrations of NaCl in the range 0.5-6.5% (w/v), pH values in the range 4.0-7.0 and storage temperatures in the range 5-30 degrees C were fitted using the Gompertz routine and the derived parameters modelled. Growth curves could then be regenerated for any set of conditions within the matrix studied and values for growth rate, generation time, lag time and time to 1000-fold increase predicted. The model was validated against data from the literature and was found to give realistic estimates for generation time in media and a range of foods including meat and meat products, milk, eggs, fish and tofu. All predictions were consistently 'fail-safe'.

Animals↗
PubMed2004

Comparing predicting models for heat inactivation of Listeria monocytogenes and Pseudomonas aeruginosa at different pH.

Under the same experimental conditions it has been demonstrated that whereas survival curves of Listeria monocytogenes in the range of temperatures from 54 to 62 degrees C followed a first-order kinetic, those of Pseudomonas aeruginosa in the range of temperatures from 50 to 56 degrees C were not linear showing a shoulder followed by a linear region. The first order kinetic model did not describe survival curves of P. aeruginosa. A model based on the Weibull distribution (Log(10)(N(t)/N(0))=(1/-2.303)*(t/b)(n))) accurately described the inactivation kinetics of both microorganisms at the three pHs of 4, 5.5, 7.4 investigated. For both microorganisms, the b value depended on the treatment temperature and the pH of the treatment medium. Whereas for L. monocytogenes the n value was independent of the treatment conditions, for P. aeruginosa the n value depended on the pH of the treatment medium. The model based on the Weibull distribution was capable of accurately predicting the treatment time to inactivate five Log(10) cycles of both microorganisms at the three pHs investigated.

Food Microbiology↗
PubMed1996

Treatment of Myocardium avium complex infection: does the beige mouse model predict therapeutic outcome in humans?

To determine the predictive value of a standard murine model in the treatment of disseminated Myocardium avium complex (MAC) infection, beige mice were infected with MAC strains isolated from human immunodeficiency virus-infected patients and treated with the same antibiotic (ethambutol, clofazimine, or rifampin) that had been administered to the subject from whom that strain had been recovered. While ethambutol had the greatest bacteriologic efficacy in humans (mean decrease +/-SD, 1.0+/-0.5 log 10 cfu/mL of blood), clofazimine had the greatest bacteriostatic efficacy in mice (mean decrease +/- SD, 2.8 +/- 0.7 log(10) cfu/g of tissue). A linear correlation was not observed between bacteriostatic activity in mouse liver or spleen and the degree of bacteriologic response in humans (P > or = to .1). Odds ratios for a response in humans based on a bacteriologic response in mice were not significant for each agent (P > or = to .1, all cases).

AIDS-Related Opportunistic Infections↗
PubMed1994

Predictive modelling of growth of Staphylococcus aureus: the effects of temperature, pH and sodium chloride.

The growth responses of Staphylococcus aureus as affected by NaCl concentration, pH value and storage temperature were studied in laboratory medium. Growth curves at concentrations of NaCl in the range 0.5-13.5% (w/v), pH values in the range 4.0-7.0 and storage temperatures in the range 10-30 degrees C were fitted using the Gompertz routine and the derived parameters modelled. Growth curves could then be regenerated for any set of conditions within the matrix studied and values for growth rate, generation time, lag time and time to 1000-fold increase predicted. The model was validated against data from the literature and was found to give realistic estimates of generation time for media and a range of foods including milk, cheese, starch-based foods and cooked meats but not for mayonnaise or Wiltshire bacon. All predictions were consistently 'fail-safe'.

Animals↗
PubMed2000

A signal detection model predicts the effects of set size on visual search accuracy for feature, conjunction, triple conjunction, and disjunction displays.

Recently, quantitative models based on signal detection theory have been successfully applied to the prediction of human accuracy in visual search for a target that differs from distractors along a single attribute (feature search). The present paper extends these models for visual search accuracy to multidimensional search displays in which the target differs from the distractors along more than one feature dimension (conjunction, disjunction, and triple conjunction displays). The model assumes that each element in the display elicits a noisy representation for each of the relevant feature dimensions. The observer combines the representations across feature dimensions to obtain a single decision variable, and the stimulus with the maximum value determines the response. The model accurately predicts human experimental data on visual search accuracy in conjunctions and disjunctions of contrast and orientation. The model accounts for performance degradation without resorting to a limited-capacity spatially localized and temporally serial mechanism by which to bind information across feature dimensions.

Adult↗
PubMed1993

How well does a three-sphere model predict positions of dipoles in a realistically shaped head?

The electrical potential produced by a dipole in the temporal or frontal lobe was calculated for a realistically shaped scalp, skull, and brain. This potential distribution was then used with a 3-sphere model to predict the position, orientation, and strength of the dipole source. The original and predicted dipole positions differed by an average of 1.97 cm, with a difference of more than 4 cm in some cases. Control calculations demonstrated that this difference was not caused by numerical artifacts in the computation, but instead was due to a true difference between the 3-sphere and realistically shaped head models.

Brain↗
PubMed2006

A probability model predicting initiation efficiency of retroviral vectors with two primer-binding sites.

Initiation of reverse transcription in retroviruses occurs at a specific point in the viral genome, called the primer-binding site (PBS). The efficiency of reverse transcription initiation is not known. We previously published a paper describing reverse transcription of the retroviral vector S-2PBS containing two PBSs. Reverse transcription of this vector results in a provirus with one of four possible structures, depending, in part, on the PBSs used to initiate reverse transcription. Using Southern blotting analyses of DNA from infected cells, we measured the relative proportions of proviruses with different structures. Although the analysis allowed us to detect multiple initiation events occurring in a single virion, the measurement of frequency of such events was not possible. In this paper, we have built a probability model, which describes the reverse transcription process and predicts the outcomes of different initiation scenarios. By fitting the predicted outcomes to the observed data, we have been able to estimate the initiation efficiency in this system as approximately 0.4 initiation per PBS. In addition, we show that even though multiple models of reverse transcription can explain the observed data, all of these models predict approximately the same initiation efficiency. This initiation efficiency is discussed in relation to general replication strategies of retroviruses.

Binding Sites↗
PubMed2005

A simple predictive model for the tensile strength of binary tablets.

The tensile strength of tablets of single-component powders, such as microcrystalline cellulose (MCC), hydroxypropylmethyl cellulose (HPMC) and starch, and binary mixtures of these powder were measured at various relative densities. It was found that the tensile strength of tablets of powder blends was primarily dependent upon relative density but was independent of the tablet dimensions and compaction kinematics. It was found that the logarithm of tensile strength was proportional to the relative density. A simple model, based upon Ryshkewitch-Duckworth equation that was originally proposed for porous materials, has been developed in order to predict the relationship between the tensile strength and relative density of binary tablets based on the properties of the constituent single-component powders. The validity of the model has been verified with experimental results for various binary mixtures. It has demonstrated that the proposed model can well predict the tensile strength of binary mixtures based upon the properties of single-component powders, such as true density, and the concentrations.

Cellulose↗
PubMed2000

How well can molecular modelling predict the crystal structure: the case of the ligand-binding domain of glutamate receptors.

The concept that the ligand-binding domain of vertebrate glutamate receptor channels and bacterial periplasmic substrate-binding proteins (PBPs) share similar three-dimensional (3D) structures has gained increasing support in recent years. On the basis of a dual approach that included computer-assisted molecular modelling and functional studies of site-specific mutants, theoretical 3D models of this domain have been proposed. This article reviews to what extent these models could predict the crystal structure of the ligand-binding domain of an ionotropic glutamate receptor subunit recently determined at high resolution by X-ray diffraction studies.

Amino Acid Sequence↗
PubMed1996

Defibrillation using a high-frequency series of monophasic rectangular pulses: observations and model predictions.

INTRODUCTION: Capacitor-discharge type waveforms are practical for defibrillation devices but may not be optimum. Discharging a capacitor as a series of high-frequency (HF) pulses may allow effective waveform shaping by modulating the pulses. This approach could lead to improved defibrillation by allowing waveforms that would otherwise be unachievable with a capacitor-discharge approach. However, little is known about defibrillation with HF. METHODS AND RESULTS: In open chest pentobarbital anesthetized dogs, we measured defibrillation thresholds for continuous rectangular waveforms with 5-, 10-, and 20-msec durations and for 10- and 20-msec long series of HF rectangular pulses. HF series had a 50% "on-time" duty cycle at 100 Hz to 20 kHz. At 1 kHz and above, defibrillation with HF required the same time-averaged current but approximately twice the peak current and energy as defibrillation with continuous waveforms having the same envelope duration. At lower frequencies, defibrillation peak current and energy approached values required for the continuous waveforms. While waveforms were not actually filtered, the heart responded as though the HF series were low-pass filtered. A filtered effective waveform model with a 3.7-msec time constant predicts these HF data and makes reasonable predictions for various continuous waveform shapes. CONCLUSION: Defibrillation is possible using HF pulses up to 20 kHz and has a frequency response similar to a low-pass filter. A filtered effective waveform model predicts these HF results and may help explain how waveforms influence defibrillation efficacy. While the unmodulated HF pulsing used in this study increased defibrillation requirements, these findings support the concept that HF pulse modulation can be used to change the effective shape of a waveform, which could permit more efficacious waveform shapes and a net reduction of thresholds.

Analysis of Variance↗
PubMed1983

A weather-based prediction model for the life-cycle of the sheep tick, Ixodes ricinus L.

The incidence of sheep tick activity depends not only on the climatic conditions within the tick habitat, but also on the rates of fecundity, development, activity, engorgement and mortality of each stage of the life-cycle. Use of existing experimental results on the effect of these factors enables a model of the life-cycle to be formulated for the purpose of predicting the occurrence of tick activity in the field where climatic conditions vary. The components of such a model are described and the predicted results compared with field studies carried out in Ireland. It is hoped that the model presented will show the potential of formulating a system for predicting tick activity. Such a system could be used to enhance the control of tick-transmitted diseases.

Animals↗
PubMed1994

Correlates and predictive models for blood pressure values in residents of two communities in Taiwan.

Factors predicting systolic blood pressure (SBP) and diastolic blood pressure (DBP) were extensively studied in residents aged 18 years and above from 10 villages in two Taiwanese communities. In women, the associated factors identified included age, body mass index, waist/hip ratio (not selected as a factor for DBP), plasma uric acid, plasma chloride, urinary sodium/creatinine ratio, urinary calcium/creatinine ratio, education level, ancestral origin, parental hypertension status, and marital status. In men, the factors were age, body mass index, plasma triglyceride concentration, urinary sodium/creatinine ratio, smoking status, alcohol drinking status, parental hypertension status (not selected for DBP), and marital status (not selected for DBP). The degree of BP variation which could be significantly explained by the measured factors differed between SBP and DBP, and differed between men and women: 18% in men and 39% in women for SBP variation; 15% in men and 27% in women for DBP variation. Factors other than those included in the models should be explored, particularly for men. This study identifies, for Chinese populations, predictive factors of BP well-known in Western societies (BMI, urinary sodium, plasma uric acid, alcohol consumption) and factors less emphasized in other studies (plasma triglyceride and marital status). A positive association between BP and urinary Na, a lack of association between BP and urinary K, and opposite findings in the relationship between BP and the education level for men (positive relation) and women (negative relation) are worth noting.

Adolescent↗