prototyping is not a substitute for thinking and careful analysis, but a vehicle for concept communication and decisiion support in the guess/check/modify process for converging to a reasonably certain formulation of the requirements

OBJECTIVE: To determine the univentricular and atrial function in patients following Fontan operation using tissue Doppler echocardiography (TDE).

SETTING: Hospital-based outpatient clinic and inpatient unit.

PATIENTS: Thirty-six patients (mean age 13 ys [2-34 ys]) after Fontan procedure and 30 healthy individuals matched for age and heart rate.

MAIN OUTCOME MEASURES: Pulsed wave Doppler derived Tei index was determined for global univentricular function. Tissue-Doppler derived strain rate and strain were measured for regional ventricular function. Different planimetric approaches were used to evaluate the global atrial function. Strain rate was measured for regional atrial contractile function.

RESULTS: The Tei index, reflecting global univentricular function, was significantly higher in Fontan patients than in the control group (p<0.001). The regional ventricular contractile function, which was determined by TDE derived strain and strain rate, was significantly lower in Fontan patients than in healthy controls (p<0.001). The global atrial function evaluated planimetrically, and the regional atrial function assessed using the TDE strain rate, were significantly lower in Fontan patients than in normal controls (p<0.001, p<0.001, respectively). A comparison of different types of Fontan operations with extra-atrial or intra-atrial baffle showed a better regional left atrial wall strain rate in patients with extra-atrial baffle than with intra-atrial baffle.

CONCLUSION: Patients who have undergone the Fontan procedure may present with altered ventricular and atrial performance independent of whether the extra-atrial or intraatrial type Fontan operation was performed. However, the regional atrial contractile function seems to be better preserved following the extra-atrial type Fontan operation.

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The Poisson regression model (PRM) is employed in modelling the relationship between a count variable (y) and one or more explanatory variables. The parameters of PRM are popularly estimated using the Poisson maximum likelihood estimator (PMLE). There is a tendency that the explanatory variables grow together, which results in the problem of multicollinearity. The variance of the PMLE becomes inflated in the presence of multicollinearity. The Poisson ridge regression (PRRE) and Liu estimator (PLE) have been suggested as an alternative to the PMLE. However, in this study, we propose a new estimator to estimate the regression coefficients for the PRM when multicollinearity is a challenge. We perform a simulation study under different specifications to assess the performance of the new estimator and the existing ones. The performance was evaluated using the scalar mean square error criterion and the mean squared error prediction error. The aircraft damage data was adopted for the application study and the estimators’ performance judged by the SMSE and the mean squared prediction error. The theoretical comparison shows that the proposed estimator outperforms other estimators. This is further supported by the simulation study and the application result.

AbstractPrevious approaches for construction project scheduling have been limited to one dimension of time for bar charts and two dimensions for linear and repetitive scheduling approaches, which added a measure of work quantity. The question therefore arises if and how it is possible to derive a three-dimensional and ultimately multi-dimensional model. Reviewing mathematical theory finds that traditional functions lack the capability to express intervals for activities. Singularity functions are therefore chosen to newly derive stationary and directional activities in a Cartesian coordinate system, wherein the two dimensions of the floor plan area plus one dimension of time are explicitly modeled in an integrated manner. They are implemented into a conflict-avoiding heuristic scheduling algorithm that minimizes total project duration, which is computerized and validated with example calculations.

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