A dimensionality reducing model for distributed filtering

The necessity of filtering noisy data generated by multidimensional processes arises in many diverse settings. The direct application of the Kalman-Bucy results is hindered by dimensionality difficulties inherent in multidimensional problems. This paper shows that for linear steady-state problems significant dimensionality reductions can be accomplished, thus making routine the solution of many interesting problems.     

Validity studies in clustering methodologies

Clustering algorithms tend to generate clusters even when applied to random data. This paper provides a semi-tutorial review of the state-of-the-art in cluster validity, or the verification of results from clustering algorithms. The paper covers ways of measuring clustering tendency, the fit of hierarchical and partitional structures and indices of compactness and isolation for individual clusters. Included are structural criteria for validating clusters and the factors involved in choosing criteria, according to which the literature of cluster validity is classified. An application to speaker identification demonstrates several indices. The development of new clustering techniques and the wide availability of clustering programs necessitates vigorous research in cluster validity.     

Multilevel difference schemes for the heat conduction equation and its application to the dirichlet problem in two and three dimensions

In this paper we have discussed a general method of deriving high order multilevel schemes for the heat conduction equation in higher dimensions. The application of the three level parabolic schemes for the solution of the steady state Dirichlet problem in two and three dimensions is discussed by introducing two parameters. The error bounds given by Hadjidimos are further refined which drastically reduces the theoretical estimate of the number of iteration cycles required for a given accuracy η. We have also defined a new set of iteration parameters. A numerical example is computed and it is seen that the present methods produce accurate results.     

P-stable singlestep methods for periodic initial-value problems involving second-order differential equations

Summary A class of P-stable singlestep methods is discussed for solving initial-value problems involving second-order differential equations. The methods depend upon a parameter p>0 and reduce to the classical methods for p=0. A few choices of p have been discussed for which the methods are P-stable. Further, when p is chosen for linear problems as the square of the frequency of the periodic solution, the methods are P-stable. Numerical results for both linear and non-linear problems show that the P-stability is an important requirement for determining periodic numerical solutions of second-order differential equations.     

New UV and IR transitions in gold, copper, and cadmium hollow cathode lasers

We have observed four additional ion laser transitions in gold, copper, and cadmium hollow cathode discharges. The new lines are at 2264 Å (Au II), 2722 Å (Cu II), 8599 Å (Au II), and 8652 Å (Cd II).     

Lack of morphine and enkephalin tolerance in 129/SvEv mice: evidence for a NMDA receptor defect

Pregnancies in outbred mammals may be regarded as successfully developed homografts. One of the hypotheses that attempts to answer the enigma of why the fetus is not rejected (fetal-maternal relationships are based on reciprocal expressions of foreign transplantation antigens) claims for the existence of possible evolutionary links between invertebrate allorecognition and mammalian implantation, based on some cellular similarities. This essay further discusses the possible evolutionary perspectives between vertebrates and invertebrates alloimmunities from a different viewpoint. We discuss similarities between natural transplantation in colonial marine invertebrates, which are followed by chimerism and a state of tolerance, and two natural transplantation events in the mammalian systems which both have records for prolonged chimerism and tolerance: the phenomenon of dizygotic twin fusions and the situation of fetal cells implantation. Earlier comparative evolutionary perspectives are revisited.     

Error Probability of a Binary Signal Perturbed by Intersymbol Interference and Impulsive Atomopheric Noise

This paper analyzes the performance of baseband polar signals in the presence of impulsive atmospheric noise and intersymbol interference (ISI). Different levels of ISI have been considered to make the analysis more meaningful. Possible explanations for the results are offered. A comparison has also been made with the system operating in Gaussian noise.