Comparing alternative classifiers for database marketing: The case of imbalanced datasets

There are various algorithms used for binary classification where the cases are classified into one of two non-overlapping classes. The area under the receiver operating characteristic (ROC) curve is the most widely used metric to evaluate the performance of alternative binary classifiers. In this study, for the application domains where the high degree of imbalance is the main characteristic and the identification of the minority class is more important, we show that hit rate based measures are more correct to assess model performances and that they should be measured on out of time samples. We also try to identify the optimum composition of the training set. Logistic regression, neural network and CHAID algorithms are implemented for a real marketing problem of a bank and the performances are compared.     

Antimicrobial Activity of Ozone against Pathogenic Oral Microorganisms on Different Denture Base Resins

ABSTRACT

The present study aimed to evaluate the antimicrobial effect of gaseous ozone against specific oral pathogens on denture base resins. 1080 round samples were prepared (10mm-diameter, 2mm-thickness). Candida albicans, Streptococcus mutans, Streptococcus gordonii, and Aggregatibacter actinomycetemcomitans, polyamide-Deflex, heat-cured polymethyl-methacrylate (PMMA)-QC-20, and cold-cured-PMMA-Meliodent. The doses and durations: 25, 50 and 100µg/ml, 5, 10, 20, 30 minutes. For Cell viability (CV) MTT was used. 100µg/ml was most effective dose for C. albicans, S .gordonii, and A. actinomycetemcomitans were in heat-cured-PMMA and polyamide for S.mutans. For polyamide, lowest CV was 43% in S.mutans and A.actinomycetemcomitans. CV of heat-cure and cold-cure PMMA were 31% and 32% in S.gordonii, respectively. CV was similar for all resins and durations in S.mutans and A.actinomycetemcomitans and for polyamide for C.albicans and for heat-cure PMMA for S.gordonii. 30-min ozone application killed 80% of all microorganisms in all resins except for C.albicans in polyamide (65% cell death) and cold-cure PMMA (57% cell death). Optimal dose/duration combination was 100 µg/ml-10 min. Gaseous ozone can be considered as an effective cleansing agent for denture base resins.     

Effect of target peak power density on the phase formation,microstructure evolution,and mechanical properties of Cr2AlC MAX-phase coatings

The applicability of Cr₂AlC MAX-phases as protective coatings in energy conversion or aerospace applications requires a dense, single-phase structure. Therefore, we study the effect of target power density and substrate bias on phase formation, microstructure evolution, and mechanical properties of Cr₂AlC coatings utilizing direct current (DCMS) and high-power pulsed magnetron sputtering (HPPMS). Generally, HPPMS results in coatings with superior density and hence larger elastic moduli compared to DCMS, indicating that ion bombardment by ionized film-forming species is beneficial. However, decreasing the substrate bias to ?200 V for DCMS and ?100 V for HPPMS favors the ion bombardment induced formation of the disordered (Cr,Al)₂C_x solid solution. It is evident that there is an optimum moderate ion energy for the formation of dense Cr₂AlC coatings. Too low energy results in the formation of under-dense coatings. Too high energy yields the formation of (Cr,Al)₂C_x in addition to Cr₂AlC.     

What input errors do you experience? Typing and pointing errors of mobile Web users

Small devices such as personal digital assistants (PDAs) are widely used to access the World Wide Web (Web). However, accessing the Web from small devices is affected by poor interface bandwidth, such as small keyboards and limited pointing devices. There is little empirical work investigating the input difficulties caused by such insufficient facilities, however, anecdotal evidence suggests that there is a link between able-bodied users of the mobile Web and motor impaired users of the Web on desktop computers. This being the case we could transfer the solutions which already exists for motor impaired users into the mobile Web and vice versa. This paper presents a user study that investigates the input errors of mobile Web users in both typing and pointing. The study identifies six types of typing errors and three types of pointing errors shared between our two user domains. We find that mobile Web users often confuse the different characters located on the same key, press keys that are adjacent to the target key, and miss certain key presses. When using a stylus, they also click in the wrong places, slide the stylus during multiple clicks, and make errors when dragging. Our results confirm that despite using different input devices, mobile Web users share common problems with motor impaired desktop users; and we therefore surmise that it will be beneficial to transfer available solutions between these user domains in order to address their common problems.     

Exploring perceptions of web accessibility: a survey approach

The equality of access – accessibility – is difficult to quantify, define, or agree upon. Our previous work analysed the responses of web accessibility specialists in regard to a number of pre-defined definitions of accessibility. While uncovering much, this analysis did not allow us to quantify the communities’ understanding of the relationship accessibility has with other domains and assess how the community scopes accessibility. In this case, we asked over 300 people, with an interest in accessibility, to answer 33 questions surrounding the relationship between accessibility, user experience (UX), and usability; inclusion and exclusion; and evaluation, in an attempt to harmonise our understanding of web accessibility. We found that respondents think that accessibility and usability are highly related and also think that accessibility is applicable to everyone and not just people with disabilities. Respondents strongly agree that accessibility must be grounded on user-centred practices and that accessibility evaluation is more than just inspecting source code; however, they are divided as to whether training in ‘Web Content Accessibility Guidelines’ is necessary or not to assess accessibility. These perceptions are important for usability and UX professionals, developers of automated evaluation tools, and those practitioners running website evaluations.     

A rare cause of abdominal pain: Catheter in the middle hepatic vein

Hemodialysis catheters are vital for chronic renal failure patients. Permanent tunneled dialysis catheters may be inserted through the jugular, subclavian, and femoral veins. In this paper, we aimed to present the computed tomography findings of a chronic renal failure patient who had referred our clinic with abdominal pain and dyspnea symptoms. This patient had a formerly inserted hemodialysis catheter for chronic renal failure and her catheter was found to be extending towards the middle hepatic vein with the tip leaning onto the parenchyma. Hemodialysis catheters can provide instant vascular access and can also be used for the consecutive procedures. Permanent hemodialysis catheters are ideal for long‐term use when placing an arteriovenous fistula is contraindicated or is no longer possible under conditions like advanced heart failure, peripheral artery disease or short life expectancy. The internal jugular, subclavian, the femoral veins, and the inferior vena cava can be used for catheter insertion. The tip of the catheters inserted in the neck or the thorax must extend to the vena cava superior. Catheter malposition may both lead to fatal outcomes and ineffective dialysis. It is important to obtain chest X‐rays after the procedure, particularly to detect catheter malposition.     

Web accessibility in Turkey: awareness,understanding and practices of user experience professionals

Universal Access in the Information Society - Ensuring web accessibility for all is not an easy task and requires the awareness, understanding and practices of people with different roles. User...