The effect of platelet-rich fibrin on autologous osteochondral transplantation: An in vivo porcine model.

BACKGROUND: This work aimed to evaluate the efficacy of cartilage transplantation to the medial femoral condyle±platelet-rich fibrin (PRF) augmentation in a porcine model. The hypothesis of the study was that PRF may act as a bioactive cell scaffold to fill defects and enhance cartilage regeneration. METHODS: Thirty-two knees of 16 miniature pigs were randomly assigned to four groups. The critical-size osteochondral defects (8x5mm) in femoral condyle of both knees were treated with one of the following: group 1－untreated controls; group 2－cartilage fragments alone; group 3－PRF alone; group 4－PRFT+cartilage fragments. After completion of the surgical implantation, the periosteal patch harvested from the proximal tibia was sutured onto the cartilage of the medial condyle to cover the implanted defects. Animals were sacrificed at six months after treatment. The regenerated cartilages were assessed by gross inspection and histological examination. RESULTS: The best results were obtained with the repair tissue being hyaline-like cartilage (group 4). The grading score of histological evaluation demonstrated that group 4 had better matrix, cell distribution and cartilage mineralization than group 2 and group 3. PRF showed a positive effect on the cartilage repair; the procedure was more effective when PRF was combined with autologous chondrocytes. CONCLUSIONS: This approach may provide a successfully employed technique to target cartilage defects in vivo. Larger groups and longer periods of study may provide more definitive and meaningful support for using this therapeutic approach as a new way of cartilage regeneration.

Frequency spectra of beam-plates revisited.

Based on Mindlin's plate theory, the frequency spectra for flexural and thickness-shear vibrations of a finite beam-plate with different combinations of boundary conditions are presented and studied. Comparing them with the dispersion curves of the infinite beam-plate reveals an intrinsic relation between resonant vibration and guided wave propagation. The fundamental frequency spectra, which are for beam-plates with hinged and/or guided edges, are found to play an important role in understanding the spectra of beam-plates with other boundary conditions.

Visualization and self-organization of multidimensional data through equalized orthogonal mapping.

A new approach to dimension-reduction mapping of multidimensional pattern data is presented. The motivation for this work is to provide a computationally efficient method for visualizing large bodies of complex multidimensional data as a relatively "topologically correct" lower dimensional approximation. Examples of the use of this approach in obtaining meaningful two-dimensional (2-D) maps and comparisons with those obtained by the self-organizing map (SOM) and the neural-net implementation of Sammon's approach are also presented and discussed. In this method, the mapping equalizes and orthogonalizes the lower dimensional outputs by reducing the covariance matrix of the outputs to the form of a constant times the identity matrix. This new method is computationally efficient and "topologically correct" in interesting and useful ways.

The ensemble approach to neural-network learning and generalization.

In this paper a new method is suggested for learning and generalization with a general one-hidden layer feedforward neural network. This scheme encompasses the use of a linear combination of heterogeneous nodes having randomly prescribed parameter values. The learning of the parameters is realized through adaptive stochastic optimization using a generalization data set. The learning of the linear coefficients in the linear combination of nodes is achieved with a linear regression method using data from the training set. One node is learned at a time. The method allows for choosing the proper number of net nodes, and is computationally efficient. The method was tested on mathematical examples and real problems from materials science and technology.

Comments on "Stochastic choice of basis functions in adaptive function approximation and the functional-link net" [and reply].

This paper includes some comments and amendments of the above-mentioned paper by Igelnik et al. (1995). Subsequently, Theorem 1 in the above-mentioned paper has been revised. The significant change of the original theorem is the space of the thresholds in the hidden layer. The revised theorem says that the thresholds of hidden b(0), should be -w(0).y(0)-u(0), where w(0)=alphaw;(0); w;(0)=(w; (01), ..., y(0d)), and u(0 ) be independent and uniformly distributed in V(d)=[0; Omega]x[-Omega; Omega](d-1), I(d), and [-2dOmega, 2dOmega], respectively. In reply, Igelnik et al. acknowledge that a factor of two was omitted in the statement of a trigonometric identity. However, the validity of the essential point of Theorem 1 is unaltered.

Neural-net computing for interpretation of semiconductor film optical ellipsometry parameters.

Optical ellipsometry has been found to be a promising technique for monitoring process parameters, such as film composition and film thickness, of semiconductor wafers grown with molecular beam epitaxy. Whereas it is a straightforward task to calculate ellipsometry angles given the thickness of the film and the refractive indexes of the film and substrate, it is a difficult task to invert that mathematical relationship. However, the process must be inverted if the measured parameters are to be interpreted meaningfully in terms of film composition and film thickness. This paper reports on the use of neural-net computing for the inverse mapping of measured ellipsometry parameters. We used a functional-link net which is very efficient in function approximation. The advantage of using the net, however, is not only its speed, but also because some other net architecture characteristics allow us to perform the task in a holistic manner.

A neural network approach for the determination of interhospital transport mode.

We report on the construction of neural networks for determining whether pediatric patients requiring transport to a tertiary care center should be moved by air or by ground. The networks were based on the functional-link net architecture. In two experiments, feedforward supervised-learning neural nets were trained with examples of an expert's decisions and then were used in a consulting mode to provide advice on cases not previously encountered. Training and validation were performed by a combination of the k-fold cross-validation and leaving-one-out sampling methods. Use of the functional-link net rather than the customary backpropagation net enabled us to carry out the training with fairly large amounts of data in realistically short time periods. In the first experiment, capillary refill, skin color, and stridor were consistently the input variables that were most strongly associated with the decision output. In both experiments, the networks were validated by comparing their performance retrospectively against the determination of an expert pediatric transport physician. The network was trained based on the expert's opinion about the correct mode of transport for each case with error rates of less than 10(-5).

Combinatorial optimization with use of guided evolutionary simulated annealing.

Feasible approaches to the task of solving NP-complete problems usually entails the incorporation of heuristic procedures so as to increase the efficiency of the methods used. We propose a new technique, which incorporates the idea of simulated annealing into the practice of simulated evolution, in place of arbitrary heuristics. The proposed technique is called guided evolutionary simulated annealing (GESA). We report on the use of GESA approach primarily for combinatorial optimization. In addition, we report the case of function optimization, treating the task as a search problem. The traveling salesman problem is taken as a benchmark problem in the first case. Simulation results are reported. The results show that the GESA approach can discover a very good near optimum solution after examining an extremely small fraction of possible solutions. A very complicated function with many local minima is used in the second case. The results in both cases indicate that the GESA technique is a practicable method which yields consistent and good near optimal solutions, superior to simulated evolution.

Stochastic choice of basis functions in adaptive function approximation and the functional-link net.

A theoretical justification for the random vector version of the functional-link (RVFL) net is presented in this paper, based on a general approach to adaptive function approximation. The approach consists of formulating a limit-integral representation of the function to be approximated and subsequently evaluating that integral with the Monte-Carlo method. Two main results are: (1) the RVFL is a universal approximator for continuous functions on bounded finite dimensional sets, and (2) the RVFL is an efficient universal approximator with the rate of approximation error convergence to zero of order O(C/ radicaln), where n is number of basis functions and with C independent of n. Similar results are also obtained for neural nets with hidden nodes implemented as products of univariate functions or radial basis functions. Some possible ways of enhancing the accuracy of multivariate function approximations are discussed.

Detection and classification of underwater acoustic transients using neural networks.

Underwater acoustic transients can develop from a wide variety of sources. Accordingly, detection and classification of such transients by automated means can be exceedingly difficult. This paper describes a new approach to this problem based on adaptive pattern recognition employing neural networks and an alternative metric, the Hausdorff metric. The system uses self-organization to both generalize and provide rapid throughput while utilizing supervised learning for decision making, being based on a concept that temporally partitions acoustic transient signals, and as a result, studies their trajectories through power spectral density space. This method has exhibited encouraging results for a large set of simulated underwater transients contained in both quiet and noisy ocean environments, and requires from five to ten MFLOPS for the implementation described.

Multicategory classification of body surface potential maps.

A statistical classification method is suggested for body surface potential maps (BSPM). The initial data reduction utilizes the Fourier expansion and time integration, resulting in physiological-oriented features. Based on Fischer's criterion, optimal discriminant vectors are used to map the features to an optimal subdomain. Experimental criteria determine the dimensionality of the subdomain and the number of features to be mapped into it. Classification is performed in two steps. In the first, a k-nearest neighbor (k-NN) rule is used for every two-category problem, the results of which are fed into a voting rule for final classification. The method is tested with 123 patients divided into four categories: normal (NR), ischemia (IS), myocardial infarction (MI), and left bundle branch block (LB) patients. The success is between 88% (for IS) and 100% (for LB) for QRS segment integration. Departure maps were used to explain the misclassified patterns.

Pseudonoise coded ultrasonic holographic imaging.

In this paper, a pseudonoise (PN) coded ultrasonic holographic imaging system design is studied with computer simulation. A system utilizing PN coded phase-modulated ultrasonic signals is capable of yielding both high lateral and high range resolution. It is found that the time for data acquisition and image reconstruction is much less than that required for some comparable methods. The PN coded imaging system also has excellent noise immunity, and this is of great practical importance. Some results for a simulated three-dimensional imaging geometry are shown to demonstrate the characteristics of PN coded ultrasound systems.

Electronic heterodyne recording and processing of optical holograms using phase modulated reference waves.

The use of a phase-modulated reference wave for the electronic heterodyne recording and processing of a hologram is described. Heterodyne recording is used to eliminate the self-interference terms of a hologram and to create a Leith-Upatnieks hologram with coaxial object and reference waves. Phase modulation is also shown to be the foundation of a multiple-view hologram system. When combined with hologram scale transformations, heterodyne recording is the key to general optical processing. Spatial filtering is treated as an example.

Telemedicine in critical care: an experiment in health care delivery.

We hypothesized that telemedicine -- medicine practiced from a distance using telecommunications -- can solve some problems related to the scarcity and maldistribution of specialists in critical care medicine. Using a two-way audiovisual link between a small private hospital and a large university medical center, we have provided daily consultations by an intensivist to patients in the small institution. During the first 175 days of the project we found: 1) regular consultations in critical care can be provided using the audiovisual link; 2) current technology is adequate but expensive; 3) telemedicine consultations can be made acceptable to users and providers; 4) telemedicine can be a valuable educational resource; 5) telemedicine can influence the process and probably the outcome of patient care; 6) the audiovisual link is superior to the telephone for these consultations; and 7) telemedicine can serve as an important link between a small hospital and a large medical center favorably influencing the quality of care in the critical care unit of the small hospital.

Optoacoustic detection of NO(2) using a pulsed dye laser.

Using a pulsed dye laser and a nonresonant optoacoustic detector, the absorption spectrum of NO(2) has been measured in the spectral region of 480-625 nm at various cell pressures and at various concentrations in air. The results of the measurements as a function of NO(2) concentration in air demonstrate the detection capability of the system. An extrapolated sensitivity of 4 ppb NO(2)/W of laser power has been achieved.

Laser optoacoustic detection of explosive vapors.

The direct detection of nitroglycerine, ethylene glycol dinitrate, and dinitrotoluene by optoacoustic spectroscopy techniques at 6 microm, 9 microm, and 11 microm is reported. The effect of interference by normal atmospheric pollutants is investigated, and it is found that of those wavelengths used in this investigation the 9-microm and 11-/microm spectral regions, using a CO(2) laser as radiation source, are the most promising for use in explosive detection.

CO(2) Laser Signature Problem.

A CO(2) laser may oscillate at any one of many possible lines. As the cavity length of such a laser is varied over a distance of lambda/2, a large number of lines oscillate one at a time in succession. The listing of the identities of the sequences of lines constitutes a signature of the laser and is a matter of practical importance in the operation of these lasers in remote controlled applications without the use of mode-selecting elements in the cavity of the laser. We report here a rather remarkable result, namely, that the lines P(20) and P(16) of the 10.4-microm band compete so effectively relative to all the other modes that they can be relied on to oscillate over quite a wide gain curve and for a wide range of operating conditions.