Improvement of a Direct Method for Outer Solution of Linear Parametric Systems

Recently, a direct method for outer solution of linear parametric systems has been suggested for the general case where the elements of the system are nonlinear functions of independent interval parameters. In this paper, an improvement of the method is introduced which may lead to a narrower outer solution.     

Effect of enzymatic degradation of chitosan in polyhydroxybutyrate/chitosan/calcium phosphate composites on in vitro osteoblast response

Polyhydroxybutyrate/chitosan/calcium phosphate composites are interesting biomaterials for utilization in regenerative medicine and they may by applied in reconstruction of deeper subchondral defects. Insufficient informations were found in recent papers about the influence of lysozyme degradation of chitosan in calcium phosphate/chitosan based composites on in vitro cytotoxicity and proliferation activity of osteoblasts. The effect of enzymatic chitosan degradation on osteoblasts proliferation was studied on composite films in which the porosity of origin 3D scaffolds was eliminated and the surface texture was modified. The significantly enhanced proliferation activity with faster population growth of osteoblasts were found on enzymatically degraded biopolymer composite films with α-tricalcium phosphate and nanohydroxyapatite. No cytotoxicity of composite films prepared from lysozyme degraded scaffolds containing a large fraction of low molecular weight chitosans (LMWC), was revealed after 10 days of cultivation. Contrary to above in the higher cytotoxicity origin untreated nanohydroxyapatite films and porous composite scaffolds. The results showed that the synergistic effect of surface distribution, morphology of nanohydroxyapatite particles, microtopography and the presence of LMWC due to chitosan degradation in composite films were responsible for compensation of the cytotoxicity of nanohydroxyapatite composite films or porous composite scaffolds.     

A New Method for Global Solution of Systems of Non-Linear Equations

In this paper the problem of finding the set of all real solutions to a system of n non-linear equations contained in a given n-dimensional box (the global solution problem) is considered. A new method for solving the global solution problem is suggested. It is based on a transformation of the original system into a larger system of separable form. The global solution of the latter system is then found in a most efficient manner by a new interval method which exploits the separabily property. Numerical examples illustrating the efficiency of the method suggested are provided.     

Comprehensive Performance Analysis of ZigBee Technology Based on Real Measurements

Although the ZigBee technology is massively deployed the performance question still remains unanswered. There is a lack of serious performance evaluations and thus this paper provides a comprehensive and unbiased study of the ZigBee PRO technology. An extensive real measurement was conducted to accomplish this task. We found out a big performance gap among ZigBee implementations even though they are compliant with the ZigBee standard. The presented results and analysis could be beneficial for many wireless sensor network developers.     

Structure–Activity Relationships of JMV4463, a Vectorized Cathepsin D Inhibitor with Antiproliferative Properties: The Unique Role of the AMPA‐Based Vector

Cathepsin D (CathD) is overexpressed and secreted by several solid tumors and stimulates their growth, the mechanism of which is still not understood. In this context, the pepstatin bioconjugate JMV4463 [Ac‐arg‐O₂Oc‐(Val)₃‐Sta‐Ala‐Sta‐(AMPA)₄‐NH₂; O₂Oc=8‐amino‐3,6‐dioxaoctanoyl, Sta=statine, AMPA=ortho‐aminomethylphenylacetyl], containing a new kind of cell‐penetrating vector, was previously shown to exhibit potent antiproliferative effects in vitro and to delay the onset of tumors in vivo. In this study, we performed a structure–activity relationship analysis to evaluate the significance of the inhibitor and vector moieties of JMV4463. By modifying both statine residues of pepstatin we found that the antiproliferative activity is correlated with CathD inhibition, supporting a major role of the catalytic activity of intracellular CathD in cancer cell proliferation. Replacing the vector composed of four AMPA units with other vectors was found to abolish cytotoxicity, although all of the conjugates enabled pepstatin transport into cells. In addition, the AMPA₄ vector must be localized at the C terminus of the bioconjugate. The unexpected importance of the vector structure and position for cytotoxic action suggests that AMPA₄ enables pepstatin to inhibit the proteolysis of critical CathD substrates involved in cell proliferation via a unique mechanism of action.     

Determining the Positive Definiteness Margin of Interval Matrices

A method for determining the positive definiteness margin of interval matrices is suggested. It is based on the use of outer interval bounds on the solution set of an interval eigenvalue problem. Three algorithms of the method are developed. It is shown that their numerical complexity is polynomial. Numerical examples illustrating the applicability of the method suggested are provided.     

Solutions to a class of non-standard non-linear H infinity control problems

This paper presents new solutions to certain non-standard non-linear H infinity control problems. We consider non-linear affine plants whose measurement output is of dimension larger than the dimension of the external input. This problem is, under proper assumptions, transformed to the problem of stabilization by means of output injection and solution of a Hamilton-Jacobi partial differential inequality arising in singular H infinity state-feedback control. General sufficient solvability conditions are given. Explicit solutions are available in the local and semilocal cases. The former concerns a certain neighbourhood of the origin in the closed loop state-space, whereas the latter assumes that the trajectories are restricted to a neighbourhood of an invariant manifold. The issue of the controller order is addressed and a reducedorder controller is obtained in the local case. A new generalization of the chain-scattering formalism provides a very useful framework for solving this problem.     

Removal of phenol from aqueous solutions by continuous RF-pertraction

Water dephenolation was studied using a multistage Rotating Film Pertractor (RFP). This relatively new liquid membrane technique allows the use of almost water-insoluble liquids as intermediate organic ‘membranes’. The effects of the main processing parameters such as disc rotation velocity, temperature and phase flowrate, on removal efficiency were studied. A mathematical model describing the process of dephenolation in a counter-current multistage cascade of n-RFP contactors was proposed for the prediction of phenol removal.     

Performance analysis of three-class classifiers: properties of a 3-D ROC surface and the normalized volume under the surface for the ideal observer

Classification of a given observation to one of three classes is an important task in many decision processes or pattern recognition applications. A general analysis of the performance of three-class classifiers results in a complex 6-D receiver operating characteristic (ROC) space, for which no simple analytical tool exists at present. We investigate the performance of an ideal observer under a specific set of assumptions that reduces the 6-D ROC space to 3-D by constraining the utilities of some of the decisions in the classification task. These assumptions lead to a 3-D ROC space in which the true-positive fraction (TPF) can be expressed in terms of the two types of false-positive fractions (FPFs). We demonstrate that the TPF is uniquely determined by, and therefore is a function of, the two FPFs. The domain of this function is shown to be related to the decision boundaries in the likelihood ratio plane. Based on these properties of the 3-D ROC space, we can define a summary measure, referred to as the normalized volume under the surface (NVUS), that is analogous to the area under the ROC curve (AUC) for a two-class classifier. We further investigate the properties of the 3-D ROC surface and the NVUS for the ideal observer under the condition that the three class distributions are multivariate normal with equal covariance matrices. The probability density functions (pdfs) of the decision variables are shown to follow a bivariate log-normal distribution. By considering these pdfs, we express the TPF in terms of the FPFs, and integrate the TPF over its domain numerically to obtain the NVUS. In addition, we performed a Monte Carlo simulation study, in which the 3-D ROC surface was generated by empirical "optimal" classification of case samples in the multidimensional feature space following the assumed distributions, to obtain an independent estimate of NVUS. The NVUS value obtained by using the analytical pdfs was found to be in good agreemen- t with that obtained from the Monte Carlo simulation study. We also found that, under all conditions studied, the NVUS increased when the difficulty of the classification task was reduced by changing the parameters of the class distributions, thereby exhibiting the properties of a performance metric in analogous to AUC. Our results indicate that, under the conditions that lead to our 3-D ROC analysis, the performance of a three-class classifier may be analyzed by considering the ROC surface, and its accuracy characterized by the NVUS.