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PubMed1996

Accident prediction models for roads with minor junctions.

The purpose of this study was to develop and validate a method for predicting expected accidents on main roads with minor junctions where traffic counts on the minor approaches are not available. The study was based on data for some 3800 km of highway in the U.K. including more than 5000 minor junctions. The highways consisted of both single and dual-carriageway roads in urban and rural areas. Generalized linear modelling was used to develop regression estimates of expected accidents for six highway categories and an empirical Bayes procedure was used to improve these estimates by combining them with accident counts. Accidents on highway sections were shown to be a non-linear function of exposure and minor junction frequency. For the purposes of estimating expected accidents, while the regression model estimates were shown to be preferable to accident counts, the best results were obtained using the empirical Bayes method. The latter was the only method that produced unbiased estimates of expected accidents for high-risk sites.

Accidents, Traffic↗
PubMed2006

[Maximal workload prediction models in the clinical cardio-pulmonary effort test].

OBJECTIVE: This study sought to derive generalized equations for predicting maximal workload for young men and women. METHODS: Direct ergospirometry (Aerosport TEEM 100, USA) was used to determine VO2máx and the maximal work load (Wmax) on the cycle ergometer test (Monark,Brazil) of thirty men (25 +/- 5 years, 75.0 +/- 10.7 kg; 48.4 +/- 8.8 mL x kg(-1) x min(-1) and 243 +/- 51 Watts) and thirty women (26 +/- 5 years, 56.7 +/- 5.9 kg, 39.8 +/- 7.6 mL x kg(-1) x min(-1) and 172 +/- 37 Watts). Age and body mass were used as independent variables. For all statistic tests, a p < 0.05 significance level was adopted. RESULTS: In the multiple linear adjustment, the maximal workload was explained by age and body mass as 54% (r = 0.73) for men, and as 76% (r = 0.87) for women, with standard errors of 0.66 W x kg(-1) and 25 Watts. The proposed equations were cross-validated using another sample with similar age and VO2máx characteristics comprised of fifteen men and fifteen women. The intraclass correlation between the predicted Wmax values and those measures by ergospirometry were 0.70 and 0.69, with standard errors of 28.4 and 15.8 Watts, respectively, for men and women. CONCLUSIONS: This study exhibits valid generalized equations for determining the maximal cycle ergonometer workload for men and women.

Adult↗
PubMed1998

Assessment of outcome prediction models for localized prostate cancer in patients managed with external beam radiation therapy.

A comparison of the ability of all published proposed clinical staging systems to predict time to prostate-specific antigen (PSA) failure after external beam radiation therapy for clinically localized prostate cancer was performed using an independent radiation database. Cox regression multivariable analyses were used to assess the significance of the proposed staging systems to predict time to post-radiation PSA failure in 465 radiation managed patients. Significant staging systems identified using Cox regression were further tested using established comparative estimates to define the most predictive system. Both the Risk Score staging system and the staging system based on the calculated volume of prostate cancer (cV(Ca)) and PSA optimized the prediction of time to post-treatment PSA failure. The cV(Ca)-PSA system, however, provided a more clinically useful stratification of outcome. Many clinical staging systems for prostate cancer have been proposed. A single clinical staging system for patients with localized prostate cancer based on parameters obtained during the routine workup provided a statistically and clinically significant stratification of outcome after external beam radiation therapy.

Humans↗
PubMedDate not supplied

[Predictive modeling of circulatory response to spinal anesthesia].

Based on the parallels between regional and systemic vasodilation, the authors examined the capacities of the sublingual nitroglycerin (500 microg) test in the predictive simulation of an individual circulatory response to subarachnoidal blockage. The integral body rheography technique developed by M. I. Tishchenko, involving signal processing in real time, was used to study the pump function of the left ventricle (LV). Assessment of the time course of changes in the latter in response to the test and blockade has established that hemodynamic stability is maintained in both cases, by increasing the LV output and capacity. Risk factors of the development of significant arterial hypotension resulting from spinal blockade could be revealed. Among them there were changes in the LV capacity index, which proved to be of the most informative value. The study has allowed the authors to develop a predictive test that is noted for its non-invasiveness and simplicity.

Administration, Sublingual↗
PubMed2001

Structure of a persistent heptachlorobornane in toxaphene (b7-1000) agrees with molecular model predictions.

A Cl(7) component of technical toxaphene (CTT), previously detected in marine mammals and fish and referred to as "7-1", was isolated from contaminated estuarine sediment using preparative solid-liquid chromatography followed by reversed-phase HPLC. The structure of this compound, elucidated by GC/MS and (1)H NMR, was 2-endo,3-exo,5-endo,6-exo,8,8,10-heptachlorobornane (hereafter referred to as B7-1000). This newly identified CTT eluted in the nonpolar fraction from silica and shares the alternating endo-exo chlorine substitution pattern with other relatively nonpolar, persistent congeners (e.g., B8-1413 and B9-1679). Based on ECNI-MS response, levels of B7-1000 in tissue samples of various higher organisms including humans were as high as 16% of B8-1413. Enantioselective determination of B7-1000 using a modified cyclodextrin chiral stationary phase (beta-BSCD) resulted in enantiomer ratios that were depleted in adipose tissue of a marine bird (skua) and Weddell seal blubber (0.3 and 0.5, respectively), but not in elephant seal blubber (1.1). Elucidation of the structure of B7-1000 thus validates previous predictions of persistence based on structure-activity relationships, chromatographic properties, and molecular modeling.

Animals↗
PubMed2000

Community-acquired pneumonia: development of a bedside predictive model and scoring system to identify the aetiology.

Although initial presentation has been commonly used to select empirical therapy in patients with community-acquired pneumonia (CAP), few studies have provided a quantitative estimation of its value. The objective of this study was to analyse whether a combination of basic clinical and laboratory information performed at bedside can accurately predict the aetiology of pneumonia. A prospective study was developed among patients admitted to the Emergency Department University Hospital Arnau de Vilanova, Lleida, Spain, with CAP. Informed consent was obtained from patients in the study. At entry, basic clinical (age, comorbidity, symptoms and physical findings) and laboratory (white blood cell count) information commonly used by clinicians in the management of respiratory infections, was recorded. According to microbiological results, patients were assigned to the following categories: bacterial (Streptococcus pneumoniae and other pyogenic bacteria), virus-like (Mycoplasma pneumoniae, Chlamydia spp and virus) and unknown pneumonia. A scoring system to identify the aetiology was derived from the odds ratio (OR) assigned to independent variables, adjusted by a logistic regression model. The accuracy of the prediction rule was tested by using receiver operating characteristic curves. One hundred and three consecutive patients were classified as having virus-like (48), bacterial (37) and unknown (18) pneumonia, respectively. Independent predictors related to bacterial pneumonia were an acute onset of symptoms (OR 31; 95% CI, 6-150), age greater than 65 or comorbidity (OR 6.9; 95% CI, 2-23), and leukocytosis or leukopenia (OR 2; 95% CI, 0.6-7). The sensitivity and specificity of the scoring system to identify patients with bacterial pneumonia were 89% and 94%, respectively. The prediction rule developed from these three variables classified the aetiology of pneumonia with a ROC curve area of 0.84. Proper use of basic clinical and laboratory information is useful to identify the aetiology of CAP. The prediction rule may help clinicians to choose initial antibiotic therapy.

Adolescent↗
PubMed1989

[Congenital malformations: a model predictive based on risk factors].

Several risk factors were studied in regard to congenital malformations. Malformed newborns (n = 1200) and controls (n = 1200) seen at the Universidad de Chile Hospital between 1969 and 1979 were examined. Their mothers were asked about possible risk factors. Parenteral age and birth order was significantly higher for malformed newborns than for controls. A family history of congenital malformations was more frequent in malformed newborns. Infertility, metrorrhagia and maternal diseases during pregnancy were more frequent in malformed newborns than in controls. A function that discriminates between controls mothers and mothers of malformed newborns was obtained by a logistic regression model. This function correctly predicted 65% of cases.

Congenital Abnormalities↗
PubMed1998

[Evaluating the risk of axillary lymph node involvement in inferior breast cancer measuring 3 centimeters. Analysis of a predictive model based on 893 cases].

STUDY AIM: The aim of the study was to assess, by clinical and histological predictive factors, the axillary lymph-node involvement (pN+) in early breast cancers. MATERIALS AND METHODS: Eight hundred ninety-three patients with unilateral invasive breast cancer were studied. The evaluated parameters included clinical size (T), pathological size (pT), histological subtype (ductal infiltrating, according to grading 1, 2, 3, lobular infiltrating and others), age (less than 40, 40 to 60 and above 60). Furthermore, a new parameter, the dosimetric breast size, recently described, was included (Eur J Cancer 1997; 33: 2432-4). RESULTS: The global rate of pN+ was 25.3%, with respectively, pN1: 10%, pN2-3: 8.4% and pN > 3: 6.9%. According to T, the pN+ rates were, respectively, 13.8%, 19.8% and 36.2% in the T0, T1 and T2 < or = 3 cm groups. According to pT, the pN+ rates were, respectively, 11.1%, 17.7%, 23.5%, 30.1% and 36% in the following groups: 0-9.9 mm, 10-14.9 mm, 15-19.9 mm, 20-24.9 mm and 25-29.9 mm. For the ductal infiltrating carcinoma, according to the gradings 1, 2 and 3, we found, respectively, 18.3%, 27.2% and 37.8% of pN+. For the lobular infiltrating carcinoma and the other histological subtypes, the rates were 22.7% and 10%, respectively. For the three age categories cited above the pN+ rates were, respectively, 30.3%, 25.8% and 22.4%. According to breast size we found 30.1% and 24.4% of pN+ respectively for small and medium or large dosimetric breast size. After a multivariate analysis, three factors were significant for pN+ risk: clinical tumor size (P = 0.0001), histological subtype (P = 0.0005) and dosimetric breast size (P = 0.004). With a combination of these three factors, the pN+ rates varied from 5% to 50%. CONCLUSIONS: The authors conclude that both clinical and pathological characteristics of the primary tumor (specified by previous core biopsy) can indicate the risk for axillary node metastases, and allow selection of candidates for limited axilla surgery (sentinel node).

Adult↗
PubMed2006

Food-web models predict species abundances in response to habitat change.

Plant and animal population sizes inevitably change following habitat loss, but the mechanisms underlying these changes are poorly understood. We experimentally altered habitat volume and eliminated top trophic levels of the food web of invertebrates that inhabit rain-filled leaves of the carnivorous pitcher plant Sarracenia purpurea. Path models that incorporated food-web structure better predicted population sizes of food-web constituents than did simple keystone species models, models that included only autecological responses to habitat volume, or models including both food-web structure and habitat volume. These results provide the first experimental confirmation that trophic structure can determine species abundances in the face of habitat loss.

Animals↗
PubMed2001

Effects of data anonymization by cell suppression on descriptive statistics and predictive modeling performance.

Protecting individual data in disclosed databases is essential. Data anonymization strategies can produce table ambiguation by suppression of selected cells. Using table ambiguation, different degrees of anonymization can be achieved, depending on the number of individuals that a particular case must become indistinguishable from. This number defines the level of anonymization. Anonymization by cell suppression does not necessarily prevent inferences from being made from the disclosed data. Preventing inferences may be important to preserve confidentiality. We show that anonymized data sets can preserve descriptive characteristics of the data, but might also be used for making inferences on particular individuals, which is a feature that may not be desirable. The degradation of predictive performance is directly proportional to the degree of anonymity. As an example, we report the effect of anonymization on the predictive performance of a model constructed to estimate the probability of disease given clinical findings.

Algorithms↗
PubMedDate not supplied

A finite-element model predicts thermal damage in cutaneous contact burns.

Thermal injury results from exposure of skin elements to an externally applied heat source. Finite-element analysis of heat transfer in cutaneous burns allows for an accurate prediction of tissue time-temperature relationships throughout the exposed tissue. A two-dimensional, axisymmetric, finite-element model of a contact burn was constructed, and damage integrals were calculated by applying the Arrhenius equation to the time-temperature profiles at each point. The epidermis, dermis, and subcutaneous fat were modeled as uniform elements with distinct thermal properties. Heated aluminum blocks were applied to Yorkshire pigs for 10 to 80 seconds to produce contact burns. Wound biopsies taken at 1, 24, and 48 hours were examined histologically and measured for the depth of burn. A significant deepening of the gelatinized tissue was observed in tissue taken from 1 hour to 24 hours. The finite-element prediction of cutaneous contact burn damage correlated well with histologic observations in this porcine model.

Animals↗
PubMed1987

Predictive models for deposition of inhaled diesel exhaust particles in humans and laboratory species.

Mathematical and computer models of the respiratory tracts of human beings and of laboratory animals (rats, hamsters, guinea pigs) were used to estimate the deposition patterns of inhaled diesel exhaust particles from automobile emissions. The accuracy of these models was tested by comparing the calculated depositions in laboratory animals with actual laboratory data. Our goal was to be able to predict the relation between exposure to diesel exhaust particles and the deposition of these particles in the lungs of humans of various ages. Diesel exhaust particles are aggregates with a mass median aerodynamic diameter of approximately 0.2 micron. Their actual size depends on the conditions under which they are generated. Using an appropriate particle model, we derived mathematical expressions that describe the effects of diffusion, sedimentation, impaction, and interception on the deposition of these particles. Because of their small size, we found that most diesel exhaust particles deposited through diffusion, and that the role of the other mechanisms was minor. Anatomical models of the human lung from birth to adulthood, as well as models of the lungs of laboratory species were formulated mathematically using available morphometric data. We used these lung models, together with the corresponding ventilation conditions of each species, to calculate deposition of diesel exhaust particles in the lungs. Under normal breathing conditions, we calculated that 7 to 13 percent (depending on particle size) of inhaled diesel exhaust particles deposit in the alveolar region of the adult human lung. Although the breathing mode (nose or mouth breathing) did not appear to affect alveolar deposition, increasing the minute ventilation (the number of breaths per minute multiplied by the tidal volume) increased alveolar deposition significantly. The calculated deposition patterns for diesel exhaust particles in younger humans (under age 25) were similar. However, with the exception of alveolar deposition in very young children (under age two), predicted deposition was greater in the lungs of younger humans than in the lungs of humans age 25 or older. For an equal exposure, the surface minute dose (particle mass deposited per minute per unit surface area) of unciliated airways appeared to change profoundly with age. Predicted dose was maximal in the lung models of two-year-old children. At this age, the calculated dose was approximately twice as high as in the mature adult lung. Deposition predictions for laboratory species compared favorably with existing data. Distribution of deposition was found to be similar among all species studied, although surface minute dose decreased with body weight.

Adolescent↗
PubMed2006

Augmenting the theory of planned behaviour with the prototype/willingness model: predictive validity of actor versus abstainer prototypes for adolescents' health-protective and health-risk intentions.

OBJECTIVES: The present research tested: (a) whether prototype perceptions and descriptive norms from the prototype/willingness model (PWM; Gibbons, Gerrard, Blanton, & Russell, 1998) enhance the prediction of adolescents' intentions to engage in health-protective and health-risk behaviours after variables from the theory of planned behaviour (TPB; Ajzen, 1991) and past behaviour have been taken into account and (b) whether images of the type of person who engages in a health behaviour (actor prototypes) and images of the type of person who does not engage in a health behaviour (abstainer prototypes) have equivalent predictive validity. DESIGN: An experimental design with a single between participants factor (actor versus abstainer prototype) was employed. METHOD: Participants in this study were 247 school pupils who completed measures of TPB variables, PWM variables and past behaviour in relation to three health-protective and three health-risk behaviours. RESULTS: Findings indicated that PWM variables accounted for a significant proportion of the variance in behavioural intentions after TPB variables and past behaviour had been taken into account (Mean deltaR2=.05). Perceived similarity to prototypes was the most consistent additional predictor of intention. Actor and abstainer prototypes exhibited equivalent predictive validity. CONCLUSIONS: The present research suggests that variables from the PWM, especially prototype similarity, enhance the predictive validity of the TPB. The findings also provide new evidence that acquiring the characteristics of both health and risk images may be goals among adolescents and suggest that both healthy and risky prototypes constitute useful cognitive targets for interventions.

Adolescent↗
PubMed1992

Distinguishing between persistent and transient impaired glucose tolerance using a prediction model.

Screening for impaired glucose tolerance (IGT) and Type 2 (non-insulin dependent) diabetes was carried out in 777 people and those with high blood glucose levels completed three 2-h oral glucose tolerance tests (OGTT). Blood lipid levels, fasting and 2-h insulin levels, body mass index, and blood pressure were also measured and family history of Type 2 diabetes recorded. Fifty people were identified with IGT and of these 21 were found to have persistent IGT and 29 transient IGT. A model including the variables body mass index, fasting and 2-h insulin levels, fasting triglycerides and family history of Type 2 diabetes was developed using the Speigelhalter-Knill-Jones weighting method to predict subjects with persistent IGT. This model could be useful in identifying people with persistent IGT and therefore eliminate the need for repeat OGTTs which are time consuming and expensive.

Blood Glucose↗
PubMed2005

A new general dynamic model predicting radionuclide concentrations and fluxes in coastal areas from readily accessible driving variables.

This paper presents a general, process-based dynamic model for coastal areas for radionuclides (metals, organics and nutrients) from both single pulse fallout and continuous deposition. The model gives radionuclide concentrations in water (total, dissolved and particulate phases and concentrations in sediments and fish) for entire defined coastal areas. The model gives monthly variations. It accounts for inflow from tributaries, direct fallout to the coastal area, internal fluxes (sedimentation, resuspension, diffusion, burial, mixing and biouptake and retention in fish) and fluxes to and from the sea outside the defined coastal area and/or adjacent coastal areas. The fluxes of water and substances between the sea and the coastal area are differentiated into three categories of coast types: (i) areas where the water exchange is regulated by tidal effects; (ii) open coastal areas where the water exchange is regulated by coastal currents; and (iii) semi-enclosed archipelago coasts. The coastal model gives the fluxes to and from the following four abiotic compartments: surface water, deep water, ET areas (i.e., areas where fine sediment erosion and transport processes dominate the bottom dynamic conditions and resuspension appears) and A-areas (i.e., areas of continuous fine sediment accumulation). Criteria to define the boundaries for the given coastal area towards the sea, and to define whether a coastal area is open or closed are given in operational terms. The model is simple to apply since all driving variables may be readily accessed from maps and standard monitoring programs. The driving variables are: latitude, catchment area, mean annual precipitation, fallout and month of fallout and parameters expressing coastal size and form as determined from, e.g., digitized bathymetric maps using a GIS program. Selected results: the predictions of radionuclide concentrations in water and fish largely depend on two factors, the concentration in the sea outside the given coastal area and/or adjacent coastal areas and the ecological half-life of the radionuclide in the sea. Uncertainties in these factors generally dominate all other uncertainties, e.g., concerning the surface water retention time, the settling velocity of the particulate fraction, the distribution coefficient regulating the fluxes in dissolved and particulate phases, the catchment area influences and the factors regulating biouptake and excretion of the radionuclide in fish. This means that the conditions in the sea are of paramount importance for the conditions in the coastal area, even for relatively enclosed coastal areas. This coastal model may be regarded as a tool for testing working hypotheses on the relative roles of different processes in different coastal areas. Such information is essential for getting realistic expectations of various remedial measures, such as coastal dredging discussed in this work.

Algorithms↗
PubMed1995

Expressed emotion, family dynamics and symptom severity in a predictive model of social adjustment for schizophrenic young adults.

While numerous studies have concluded that high expressed emotion (EE) in relatives predicts relapse in schizophrenia, other aspects of patient outcome have not been well studied. Our purpose was to determine the extent to which family dynamics and expressed emotion may predict variance in patient social adjustment when controlling for symptom severity. Sixty-nine schizophrenic outpatients and 108 of their relatives participated. Relatives' EE was assessed, and they were administered the FACES III for perceptions of family cohesion and adaptability. Patients were interviewed at about the same time as their relatives and again 9 months later with the Social Adjustment Scale (SAS-II) and the BPRS. Between 9% and 58% of variance in each of the five SAS scales was explained by selected EE and family dynamics scales, while symptom severity was held constant. Among the results, it was found that better social adjustment in patients was associated with less family adaptability, and with greater emotional overinvolvement in relatives. Adjustment of patients in the work role was associated with more Critical Comments from mothers. In conclusion, some aspects of high EE are associated with better social adjustment in schizophrenic patients.

Adolescent↗
PubMed1997

Physiology of chemotherapy-induced emesis and antiemetic therapy. Predictive models for evaluation of new compounds.

The physiology of emesis has been studied for several hundred years, focusing on the different centres involved and the mechanics of expulsion. The vomiting centre receives inputs from various emetic detectors such as the gut, the vestibular labyrinths and the chemoreceptor trigger zone. Emesis is a common disabling effect in motion sickness, postoperative conditions and in radio- and chemotherapy. Our current understanding of the mechanisms has been provided mainly by the recent introduction of serotonin 5-HT3 receptor antagonists into therapeutic use. Nevertheless, despite the considerable advances made in the understanding of the different pathways involved in emesis, there are number of areas that still require experimental investigation. Different animal and human models are available to study the physiology of emesis and to evaluate the antiemetic activity of new compounds, but they need to be predictors of clinical situations.

Animals↗