Internal Validity Index for Fuzzy Clustering Based on Relative Uncertainty

Unsupervised clustering and clustering validity are used as essential instruments of data analytics. Despite clustering being realized under uncertainty, validity indices do not deliver any quantitative evaluation of the uncertainties in the suggested partitionings. Also, validity measures may be biased towards the underlying clustering method. Moreover, neglecting a confidence requirement may result in over-partitioning. In the absence of an error estimate or a confidence parameter, probable clustering errors are forwarded to the later stages of the system. Whereas, having an uncertainty margin of the projected labeling can be very fruitful for many applications such as machine learning. Herein, the validity issue was approached through estimation of the uncertainty and a novel low complexity index proposed for fuzzy clustering. It involves only uni-dimensional membership weights, regardless of the data dimension, stipulates no specific distribution, and is independent of the underlying similarity measure. Inclusive tests and comparisons returned that it can reliably estimate the optimum number of partitions under different data distributions, besides behaving more robust to over partitioning. Also, in the comparative correlation analysis between true clustering error rates and some known internal validity indices, the suggested index exhibited the highest strong correlations. This relationship has been also proven stable through additional statistical acceptance tests. Thus the provided relative uncertainty measure can be used as a probable error estimate in the clustering as well. Besides, it is the only method known that can exclusively identify data points in dubiety and is adjustable according to the required confidence level.     

Efficacy of different surface treatments and universal adhesives on the microtensile bond strength of bulk-fill composite repair

Abstract

The purpose of this in vitro study was to evaluate the influence of different surface treatments and aging on the microtensile bond strength (μTBS) of bulk-fill composite resins. Bulk-fill composites (Filtek One; 3M ESPE) randomly received five different surface treatments: (1) no treatment, control, (2) 37% phosphoric acid etching (PA), (3) 9% hydrofluoric acid etching (HF), (4) air-borne particle abrasion with 50-μm alumina particles (Al₂O₃), (5) tribochemical silica coating (CoJet). Following, the specimens were divided into three subgroups according to universal adhesive applied: Clearfil Universal Bond (CU; Kuraray), Prime&Bond Universal (PBU; Dentsply Sirona), or Single Bond Universal (SBU; 3M ESPE). A nanofill composite (Filtek Ultimate; 3M ESPE) was employed as a repair. Bonded specimens were stored in water for 24?h at 37?°C or thermal aged, then subjected to the μTBS test. Additionally, specimens were analyzed with a contact profilometer and were evaluated with scanning electron microscopy. Control and PA treatments were showed the lowest µTBS (p?<?0.05), and there was no significant difference between these two groups (p?>?0.05). Al₂O₃ and CoJet treatments generally exhibited a similar influence on µTBS values. In addition, a correlation was found between surface roughness and bond strength (r?=?0.831). CoJet resulted in significantly higher repair µTBS values when compared to the other surface treatments. In addition, the use of silane-containing universal adhesive was increased the cohesive failure rate and maintained the repair µTBS values after thermocycling.     

Elasticity of real networks: Comparison of molecular theory with experiments

Predictions of the theory of elasticity of real networks are compared with results of experiments. The shape of the stress-strain curve for networks in the dry and swollen states and over wide ranges of strain, both in tension and compression, agrees with results of calculations based on the theory. The theory is also in close agreement with results of multiaxial stress-strain experiments and with the predictions of the degree of crosslinking obtained from measurements of the modulus. The theory may additionally be applied to the analysis of birefringence. The assumption of the linear additivity of the elastic and mixing free energies in a swollen network leads to results which are in agreement with experimental findings on different crosslinked systems.     

The effect of aprotinin on extraneural scarring in peripheral nerve surgery: an experimental study

BACKGROUND: Although laser resurfacing has become increasingly popular in the treatment of Caucasian skin, concerns about healing and postinflammatory pigmentary changes have limited its use in Asian skin. OBJECTIVE: The purpose of this study was to determine the efficacy and safety of the Erbium(ER):YAG laser used in the treatment of Asian skin. METHODS: Fifty Asian individuals with Rhytids, scars, pigmentary alteration, and a variety of cutaneous growth were treated with the Erbium:YAG laser. Patients were evaluated for clinical efficacy, wound healing, post-operative erythema, and post-inflammatory pigmentary changes. RESULTS: Significant improvement was noted in all individuals. Shorter periods for re-epithelization and erythema duration were noted when compared to previously reported results following carbon dioxide laser resurfacing. CONCLUSION: The Erbium:YAG laser is safe and effective in the treatment of Asian skin.     

Effects of lead on the activity of delta-aminolevulinic acid dehydratase in Gammarus pulex

During severe sepsis there is dramatic activation of both contact proteases and the coagulation pathway. These processes contribute to the development of shock and disseminated intravascular coagulation (DIC) respectively. The Pittsburgh mutant of antitrypsin (358Met-Arg) is a novel protease inhibitor with activity against both thrombin and the contact proteases and should therefore prove beneficial as a therapeutic agent in the management of septic shock. This hypothesis was supported by an earlier study in a pig model where recombinant antitrypsin Pittsburgh (rAT Pittsburgh) at a concentration of 1 microM alleviated some of the features of shock, but did not improve survival. In order to reduce the lethal effects of E. coli sepsis we postulated that a higher concentration of antitrypsin Pittsburgh would be necessary. To test this hypothesis we used rAT Pittsburgh in a primate model. This was chosen in preference to another species as E. coli sepsis in the primate has been well characterised and closely resembles the changes seen in man. Surprisingly this treatment did not alleviate the features of shock and unexpectedly appeared to exacerbate the associated coagulopathy. We propose two possible mechanisms for this unforeseen outcome. The first results from the broad spectrum of activity of antitrypsin Pittsburgh. As well as inhibiting thrombin and the contact proteases, the Pittsburgh mutant also inhibits activated protein C. Inhibition of the protein C system is known to exacerbate septic shock. Secondly, a significant quantity of inactive antitrypsin Pittsburgh, cleaved at the reactive centre, was detected in the plasma of the treated animals. Proteolytically altered serpins, including antitrypsin. have been shown to enhance the inflammatory process. Therefore the accumulation of cleaved rAT Pittsburgh might be expected to exacerbate septic shock.     

Composite panels containing multiple through-the-width delaminations and subjected to compression. Part II: Experiments & verification

The objective of this investigation was to perform compression tests on laminated composites for verifying the analytical model and the finite element analysis previously developed by the authors for analyzing compression response of composite panels containing multiple delaminations. T300/976 graphite/epoxy composite was selected for the study. Specimens with various ply orientations were fabricated from both flat and cylindrical composite panels containing one to two pre-implanted through-the-width delaminations. Specimens were tested by uniaxial compression, and strain gauges were utilized to record the strain history as a function of the applied load from initial loading to final failure. Numerical simulations were performed according to the test conditions. Comparisons were then made between the predictions and the measured test data. Overall, the predictions agreed with the data very well. Parametric studies were also performed using the finite element analysis to demonstrate the effect of the size, location and number of the delaminations on the compression response of laminated composites.     

Composite panels containing multiple through-the-width delaminations and subjected to compression. Part I: Analysis

An analytical and experimental investigation was performed to study the compression response of laminated composite panels containing multiple through-the-width delaminations. Both flat and cylindrical panels were considered. The major objective of the study was to develop an analytical model for simulating the deformations of the laminated panels from initial loading to final collapse. The model consists of three parts: a stress analysis, a contact analysis, and a failure analysis. A nonlinear finite element code was developed based on the model. Extensive experimental work on T300/976 composites was also conducted during the investigation to verify the model and the numerical calculations.

The results of the study will be presented in two parts: I — Analysis and II — Experiments. In this paper, the development of the analytical model, the implementation of the model into the finite element code, and comparisons between the calculations based on the model and the existing analytical and experimental results will be presented. The experiments performed during the investigation, and the comparisons between the calculations and the test data will be given in the second paper.