The effect of dentin desensitizers and Nd:YAG laser pre-treatment on microtensile bond strength of self-adhesive resin cement to dentin

Acar, Ozlem,Tuncer, Duygu,Yuzugullu, Bulem,Celik, Cigdem The Korean Academy of Prosthodonitics 2014 The Journal of Advanced Prosthodontics Vol.6 No.2

PURPOSE. The purpose of this study is to evaluate if pre-treatment with desensitizers have a negative effect on microtensile bond strength before cementing a restoration using recently introduced self-adhesive resin cement to dentin. MATERIALS AND METHODS. Thirty-five human molars' occlusal surfaces were ground to expose dentin; and were randomly grouped as (n=5); 1) Gluma-(Glutaraldehyde/HEMA) 2) Aqua-Prep F-(Fluoride), 3) Bisblock-(Oxalate), 4) Cervitec Plus-(Clorhexidine), 5) Smart protect-(Triclosan), 6) Nd:YAG laser, 7) No treatment (control). After applying the selected agent, RelyX U200 self-adhesive resin cement was used to bond composite resin blocks to dentin. All groups were subjected to thermocycling for 1000 cycles between $5-55^{\circ}C$. Each bonded specimen was sectioned to microbars ($6mm{\times}1mm{\times}1mm$) (n=20). Specimens were submitted to microtensile bond strength test at a crosshead speed of 0.5 mm/min. Kolmogorov-Smirnov, Levene's test, Kruskal-Wallis One-way Analysis of Variance, and Conover's nonparametric statistical analysis were used (P<.05). RESULTS. Gluma, Smart Protect and Nd:YAG laser treatments showed comparable microtensile bond strengths compared with the control group (P>.05). The microtensile bond strengths of Aqua-Prep F, and Cervitec Plus were similar to each other but significantly lower than the control group (P<.05). Bisblock showed the lowest microtensile bond strength among all groups (P<.001). Most groups showed adhesive failure. CONCLUSION. Within the limitation of this study, it is not recommended to use Aqua-prep F, Cervitec Plus and Bisblock on dentin when used with a self-adhesive resin cement due to the decrease they cause in bond strength. Beside, pre-treatment of dentin with Gluma, Smart protect, and Nd:YAG laser do not have a negative effect.

Comparison of micro-computerized tomography and cone-beam computerized tomography in the detection of accessory canals in primary molars

Acar, Buket,Kamburoglu, Kivanc,Tatar, Ilkan,Arikan, Volkan,Celik, Hakan Hamdi,Yuksel, Selcen,Ozen, Tuncer Korean Academy of Oral and Maxillofacial Radiology 2015 Imaging Science in Dentistry Vol.45 No.4

Purpose: This study was performed to compare the accuracy of micro-computed tomography (CT) and cone-beam computed tomography (CBCT) in detecting accessory canals in primary molars. Materials and Methods: Forty-one extracted human primary first and second molars were embedded in wax blocks and scanned using micro-CT and CBCT. After the images were taken, the samples were processed using a clearing technique and examined under a stereomicroscope in order to establish the gold standard for this study. The specimens were classified into three groups: maxillary molars, mandibular molars with three canals, and mandibular molars with four canals. Differences between the gold standard and the observations made using the imaging methods were calculated using Spearman's rho correlation coefficient test. Results: The presence of accessory canals in micro-CT images of maxillary and mandibular root canals showed a statistically significant correlation with the stereomicroscopic images used as a gold standard. No statistically significant correlation was found between the CBCT findings and the stereomicroscopic images. Conclusion: Although micro-CT is not suitable for clinical use, it provides more detailed information about minor anatomical structures. However, CBCT is convenient for clinical use but may not be capable of adequately analyzing the internal anatomy of primary teeth.

A Comparison of Models for Predicting Discretionary Accruals: A Cross-Country Analysis

ACAR, Goksel,COSKUN, Ali Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.9

In this study, we examined various aspects of discretionary accruals. We compared the power of Jones Model (JM), Modified Jones Model (MJM) and Performance Matched Model (PMM). Furthermore, we tested whether accruals derived from cash flow approach or balance sheet approach provide better results and we investigated the significance of country and industry control variables in models. In order to perform these tests, we constructed thirty equations. The data consists of 319 non-financial companies over five years in the GCC region. We used panel data regression models, and testing suggests us to use random effect model as the most suitable one. The results show that PMM has the highest explanatory power among models and it is followed by JM and MJM, consecutively. Secondly, results reveal that accruals derived from cash flow approach provide more accurate results. Moreover, country dummies are significant in models with cash flow approach and they lose significance in balance sheet approach. We differentiated industries due to two different classifications: the first group with higher number of industries is more precise compared to the second group with a narrower scope and lower number of industries. The model including both industrial and country-wise dummies scores highest in significance.

The Mechanical Effect of Rod Contouring on Rod-Screw System Strength in Spine Fixation

Acar, Nihat,Karakasli, Ahmet,Karaarslan, Ahmet A.,Ozcanhan, Mehmet Hilal,Ertem, Fatih,Erduran, Mehmet The Korean Neurosurgical Society 2016 Journal of Korean neurosurgical society Vol.59 No.5

Objective : Rod-screw fixation systems are widely used for spinal instrumentation. Although many biomechanical studies on rod-screw systems have been carried out, but the effects of rod contouring on the construct strength is still not very well defined in the literature. This work examines the mechanical impact of straight, $20^{\circ}$ kyphotic, and $20^{\circ}$ lordotic rod contouring on rod-screw fixation systems, by forming a corpectomy model. Methods : The corpectomy groups were prepared using ultra-high molecular weight polyethylene samples. Non-destructive loads were applied during flexion/extension and torsion testing. Spine-loading conditions were simulated by load subjections of 100 N with a velocity of $5mm\;min^{-1}$, to ensure 8.4-Nm moment. For torsional loading, the corpectomy models were subjected to rotational displacement of $0.5^{\circ}\;s^{-1}$ to an end point of $5.0^{\circ}$, in a torsion testing machine. Results : Under both flexion and extension loading conditions the stiffness values for the lordotic rod-screw system were the highest. Under torsional loading conditions, the lordotic rod-screw system exhibited the highest torsional rigidity. Conclusion : We concluded that the lordotic rod-screw system was the most rigid among the systems tested and the risk of rod and screw failure is much higher in the kyphotic rod-screw systems. Further biomechanical studies should be attempted to compare between different rod kyphotic angles to minimize the kyphotic rod failure rate and to offer a more stable and rigid rod-screw construct models for surgical application in the kyphotic vertebrae.

Agricultural Unskilled Labor Mobility : Does It Matter?

ACAR, Mustafa 세종대학교 국제경제연구소 2003 Journal of Economic Integration Vol.18 No.1

Labor mobility is on important issue in quantiative economic analyses due to its possible implications for the sectoral reallocation of factors of production, output response, prices, and wages. This paper investigates the issue of agricultural unskilled labor mobility from both modeling and empirical perspectives. After discussing the issue from a theoretical perspective, I look into the empirical implications fo treating agricultural unskilled labor less than mobile in the context of Turkey-EU agricaultural integration. The results indicate that degree of mobility of the agricultural unskilled labor moatters. It has certaqtin implications on sectoral labor mobility between farm and non-farm sectors, the higher the output response, and the lower the real earnings of unskilled labor in agriculture.

Perspectives of Women during Reproductive Years for Cervical Cancer Scans and Influencing Factors

Acar, Gokce Banu,Pinar, Gul Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.16

Background: This descriptive study was performed in order to assess health perspectives of women, who applied to Yildirim Beyazit University Ataturk Education and Research Hospital, Outpatient Clinic of Obstetrics and Gynecology for cervical cancer scans and were in the reproductive years. Factors influencing their perspectives were also assessed. Materials and Methods: In this study, a simple random sampling formula was adopted to calculate the volume (300) of the targeted sample. Results of the research were obtained through individual diagnosis form and cervical cancer and the Pap smear test health belief model scale (HBMS). Results: It was found that 75.0% of the women heard of the Pap smear test before, and 48.7% had undertaken one. Some 51.4% of the women who had Pap smear test expressed that they had the test at irregular periods. Most of the women stated that they heard about the smear test from the health staff (51.7%). Lack of any health complaints (28.3%) and not having adequate information about the test (21.0%) were among the reasons for not undergoing a Pap smear test. It was found that lower dimension average scores of the women obtained from the cervical cancer and Pap smear test HBMS varied from $7.7{\pm}2.3$ to $33.5{\pm}9.3$. When the lower dimension average scores of women from the HBMS were examined, the perception of usefulness was high but the susceptibility and health motivations were low. Conclusions: In this study, it was determined that the awareness of women about cervical cancer and the Pap smear test was insufficient, and susceptibility and motivation perception towards having a Pap smear test were low.

LEVERAGING BIG DATA AND ARTIFICIAL INTELLIGENCE FOR SERVICE INNOVATION IN MARKETING

Murat Acar,Aysegul Toker 글로벌지식마케팅경영학회 2020 Global Marketing Conference Vol.2020 No.11

Comparison of micro-computerized tomography and cone-beam computerized tomography in the detection of accessory canals in primary molars

Buket Acar,Kıvanc Kamburoglu,İlkan Tatar,Volkan Arıkan,Hakan Hamdi Çelik,Selcen Yüksel,Tuncer Özen 대한영상치의학회 2015 Imaging Science in Dentistry Vol.45 No.4

Purpose: This study was performed to compare the accuracy of micro-computed tomography (CT) and cone-beam computed tomography (CBCT) in detecting accessory canals in primary molars. Materials and Methods: Forty-one extracted human primary first and second molars were embedded in wax blocks and scanned using micro-CT and CBCT. After the images were taken, the samples were processed using a clearing technique and examined under a stereomicroscope in order to establish the gold standard for this study. The specimens were classified into three groups: maxillary molars, mandibular molars with three canals, and mandibular molars with four canals. Differences between the gold standard and the observations made using the imaging methods were calculated using Spearman’s rho correlation coefficient test. Results: The presence of accessory canals in micro-CT images of maxillary and mandibular root canals showed a statistically significant correlation with the stereomicroscopic images used as a gold standard. No statistically significant correlation was found between the CBCT findings and the stereomicroscopic images. Conclusion: Although micro-CT is not suitable for clinical use, it provides more detailed information about minor anatomical structures. However, CBCT is convenient for clinical use but may not be capable of adequately analyzing the internal anatomy of primary teeth.

Rate of convergence for generalized Szasz operators with derivatives of bounded variation

TUNCER ACAR 장전수학회 2013 Proceedings of the Jangjeon mathematical society Vol.16 No.1

The present paper deals with the general integral modi…-cation of the Szasz-Mirakyan operators having the weight functions ofgeneral Baskakov basis functions.We estimate the rate of convergencefor functions having derivatives of bounded variation.

A PERCEIVED SERVICE QUALITY MODEL IN SHARING ECONOMY: THE CASE OF AIRBNB

Murat Acar,Aysegul Toker 글로벌지식마케팅경영학회 2018 Global Marketing Conference Vol.2018 No.07

Introduction The idiom “you are what you own” has been considerably transformed into “you are what you can access”. The shift from ownership to access, the results of endless hyper-consumption, and the change in value mindsets initiated a new phenomenon, which is Sharing Economy (SE). SE has grown rapidly and refers to an entirely new business model, socio-economic ecosystem, and context for sharing the access to goods and services in technology-enabled peer-to-peer (P2P) ecosystems or consumer-to-consumer (C2C) engagement platforms. According to Botsman and Rogers (2010), SE is a result of the linkage between offline and online world, which was triggered by the society to overcome natural resources constraints. Resources in SE can be tangible (e.g., cars and homes) and intangible (e.g., expert local knowledge and labor). SE allows the sustainable use of idle resources, and it enables sellers to create new and flexible opportunities to market to consumers who experience personalized and even customized products and services at lower prices (Yang, Song, Chen, & Xia, 2017). SE opened up new horizons for a considerable number of new players across industries from a supply perspective by broadening the options for supply, which also remedies the response to peak demand. SE has given a rise to the humanization of consumer-supplier relationship in tourism and hospitality (TH), and sharing has become a mainstream practice in this context. The recent shift of customers‟ willingness to share accommodation with a host as opposed to using a private hotel room has many implications for TH (Lu & Kandampully, 2016). For example, Airbnb has become one of the most prominent competitors in hotel industry, and it enables people to lease or rent short-term accommodation including vacation rentals, apartment rentals, homestays, and even experiences via instant booking. From cash-strapped travelers to high-end business travelers, Airbnb has revolutionized the TH service in a new form of contractual relationship and gained a well-grounded popularity. Some scholars, on the other hand, argued that SE is a “fundamentally different business model” which could make it a new marketplace instead of a direct competitor in hotel industry. From this point of view, Airbnb do not compete or pose a challenge to traditional TH services but extend the concept of TH (Lu & Kandampully, 2016). Hotel industry has reactively responded to the direct, indirect, and induced effects of Airbnb to economy, and Airbnb‟s impact on hotel industry have recently been researched by several scholars (Mody, Suess, & Lehto, 2017; Priporas, Stylos, Rahimi, & Vedanthachari, 2017; Zervas, Proserpio, & Byers, 2017). Customer engagement in TH has been empirically found to enhance customers‟ service brand evaluation, brand trust, and brand loyalty (So, King, Sparks, & Wang, 2016). Guests attach great importance to motivational drivers, more meaningful “beyond-purchase” social interactions and unique experiences in authentic settings, which give rise to customer engagement beyond the service encounter. Disruptive innovation theory also states that products or services that offer alternative benefits compared to conventional attributes can transform a market and attain a critical mass, which can be observed in Airbnb‟s story (Young, Corsun, & Xie, 2017). Airbnb is successfully promoting the mottos of “Belong Anywhere” and “Don’t Go There. Live There” to their guests. The feelings of trust and belonging were negatively changed by mass production and noncustom travel experiences, and people sometimes forgot the meaning of community due to high tendency of prestige and advertising. Consumers‟ changing attitudes towards utilization and accessibility compared to ownership created an indirect need for intimate connection between people, namely human connection. Then, social concerns upon products and services gave a rise to mass-customized product and service expectations of consumers. This is where Airbnb‟s value proposition comes into play. First, it creates not only financial but also personal rewards through a “personal concierge” and a “home away from home” experience. Second, Airbnb is not a simple transaction, rather it is deemed to be a lifetime experience. So “guest experience” is at the heart of Airbnb‟s strategic position. From the “experience” point of view, SE has also opened up new rooms for service research. Service in the context of Airbnb is considered as an experience, rather than a utilitarian relation. Also, service quality has always been a critical factor in highly-competitive service industries like TH. Service quality perception is multi-faceted, and the studies focusing on it are rather limited, especially in hotel industry. These studies highlighted the complexities associated with evaluating service quality and the contribution of service process delivery on service outcomes, which results in the perception of service quality. Therefore, perceived service quality can be influenced by different internal processes and interpersonal variables. In order to study service quality in Airbnb, the types of settings in this context are to be noted. There are two main types of hosting via Airbnb: (1) remote hospitality, which refers to hosting situations in which the host does not physically share the place with the guest (e.g. booking the entire place), and (2) on-site hospitality, where the host is physically present and sharing the apartment with the guest. Mainly, on-site hospitality is an important part of the sociability within the host–guest relationship. Priporas et al. (2017) studied service quality in the context of remote hospitality, and we decided to respond to their relevant call for future research on the other type of Airbnb accommodation, which is on-site hospitality referring to “Shared Rooms” and “Private Rooms” in Airbnb‟s listings. “Shared Rooms” refer to an exact communal experience with the host, and guests sleep in a space that is shared with others and share the entire space with other people. “Private Rooms” refer to privacy, to some extent, in which guests (i) value a local connection (ii) have their own private room for sleeping and (iii) may share some spaces with others. We do expect that human connection and experience gap can be better researched with on-site hospitality existing in “Shared Rooms” and “Private Rooms”. This is because hosts design their services to create and build a relationship with their guests, leading to superior guest experiences and the so-called positive moment-of-truth. In addition to the online storytelling on hosts‟ home pages, the most important moment-of-truth is created during the guests‟ stay at the host‟s place; thus, the host plays a major role in the customer‟s perception of service and the subsequent review of the experience (Lu & Kandampully, 2016). Considering the previously mentioned “experience gap” in the literature, our research question and relevant sub-questions are as follows: • What are the antecedents of perceived service quality in Airbnb on-site hospitality? o How well does SERVQUAL suffice for measuring perceived service quality in this context? o How well the cognitive and attitudinal factors expand this measurement? o What are the additional perceived service quality factors that can be derived from guests‟ online textual reviews to remedy the “experience gap”? Literature review Cheng (2016) conducted a systematic review of SE by using co-citation and content analysis of papers, and the findings reveal three distinct research areas of SE: (1) SE‟s business models and its impacts, (2) Nature of SE, and (3) SE‟s sustainability development. Moreover, two unique areas, specifically in TH, were identified: (1) SE‟s impacts on destinations and TH services and (2) SE‟s impacts on tourists. The comparison of both literatures has revealed limited expansion in TH literature despite the fact that TH are at the frontier of SE (Cheng, 2016). Pesonen and Tussyadiah (2017) conducted cluster analysis to identify user profiles corresponding to consumer motivations for using TH services of SE. They concluded that a consumer group uses TH services of SE to make their trips more convenient, while another group uses these services mostly for social reasons. Yang et al. (2017) studied the loyalty in SE services from relational benefits perspective and concluded that confidence and social benefits have significant and positive effects on commitment in SE services. Molz (2014) introduced the term „Network Hospitality‟, which is relatively new and rooted in old traditions of welcoming strangers. Airbnb represents just one of many types of network hospitality, and in Airbnb, trust is almost shaped based on peer reviews, not solely on one-to-one peer interactions. The online review information becomes the basis for members‟ reputation in the network. The information accumulated on Airbnb‟s online platform helps both parties to establish their reputation, as well as publicizing their personalities, thereby facilitating the process of finding the best match. Moreover, there are hundreds of people working in Airbnb‟s customer service, trust, and safety departments who are devoted to ensuring the intimacy provision of trusted services. Airbnb requires all hosts to abide by their “Hospitality Standards”, which include expected levels of cleanliness, commitment, and communication. The flexibility, reliability, and consistency of Airbnb‟s service providers help them to build and maintain the relationship Airbnb enjoys with their guests and hosts (Lu & Kandampully, 2016; Zervas et al., 2017). Pine and Gilmore (1998) predicted the rise of experience in their seminal study, referring to the “experience economy” and also stating “As goods and services become commoditized, the customer experiences that companies create will matter most.” They called this as “Staging Experiences”. Also, there exists evidence in literature that providers are shifting their focus from product- and service-oriented to design of quality experiences. In terms of the glamour of SE in TH, a “more unique experience” is deemed to be second only to better pricing. Airbnb may eventually address all elements of the accommodation experience, from travel reservations to ticketing for local attractions. Consumers are looking for local authenticity in their travels. Psychological authenticity refers to emotional genuineness, self-attunement, and psychological depth (Walls, Okumus, Wang, & Kwun, 2011). If TH industry is to surpass its SE competition in terms of guest experience, it should leverage an expanded experience economy paradigm that incorporates additional dimensions (Mody et al., 2017). Authentic host-guest experiences probably only exist between like-minded and privileged members who possess high cultural capital (Cheng, 2016). With that, Walls et al. (2011) have suggested the need for researchers to identify specific dimensions “that exist in both our everyday and tourist experiences”. Both in Airbnb and traditional TH, guest satisfaction and likelihood to reuse are driven by similar factors such as quality and utility of services, trust to the host, and economic value. There are several models for measuring service quality, including SERVQUAL (Parasuraman, Zeithaml, & Berry, 1988) and SERVPERF (Cronin & Taylor, 1992). Service quality literature received widespread attention after the seminal work by Parasuraman et al. (1988) as they proposed the gap model and developed SERVQUAL (an attribute-based technique) as a tool for measuring service quality. According to SERVQUAL, service quality consists of five dimensions measured by a total of 22 items. The proposed five service quality dimensions are tangibles, reliability, responsiveness, assurance, and empathy. SERVQUAL basically requires measures of expectations and performance, and service quality is calculated from subtractions between these two components (i.e., performance [P] - expectations [E]). Regarding service quality in TH, Akbaba (2006) utilized SERVQUAL for business hotels, and Priporas et al. (2017) inquired SERVQUAL‟s applicability in Airbnb context with promising results. The major distinction between two research directions (i.e. hotels vs. Airbnb) is that even though guests expect similar core services such as clean rooms and comfortable beds, different attributes support the competitive advantage of hotels and Airbnb. While conveniences offered by hotels are unparalleled by Airbnb accommodation, the latter appeal to consumers driven by experiential and social motivations (Pesonen & Tussyadiah, 2017). Research model This research aims to identify the antecedents of perceived service quality of guests‟ in Airbnb on-site hospitality context. Our research model is presented in Figure 1, and it is subject to enhancement through the analytics of guest reviews. A survey will be developed to test the proposed research model. The items of constructs will be mainly derived from extant literature and enriched with the linguistic and textual analysis of reviews. Firstly, factors shaping expectation are predicted as per the literature and preliminary analysis of random guest reviews: (i) host‟s reputation capital (e.g., ratings and reviews), (ii) host‟s photos, (iii) guest‟s past accommodation experience, and (iv) word of mouth. Secondly, SERVQUAL part in the model is the same as proposed by Parasuraman et al. (1988). Last but not least, Airbnb is deemed to promote global geographical imaginaries (e.g., collaboration, social equity, solidarity, community, trust, reciprocity, altruism, autonomy, intimacy, and authenticity) to justify their business model (O‟Regan & Choe, 2017). Finally, regarding the guest review analysis, Airbnb has a detailed review mechanism, and we have gathered the publicly available reviews that are up to 500 words. We have observed cognitive and attitudinal dimensions within reviews through text analytics and grouped those in the research model as follows: • Intimacy: The emergence of intimacy as a commercial value in TH industry has been researched. (e.g., How well people know each other? How people occupy space together? How people share private information, family pictures, furniture choice etc.?) (Prager, 1997) • Authenticity: We focus on the existential authenticity (i.e., being one‟s true self or being true to one‟s essential nature) from guests‟ perceptions (e.g., Is Airbnb like ‘living the local life’?) (Lalicic & Weismayer, 2017) • Commitment: It refers to the consistent behavior of Airbnb hosts in terms of social and cost components. (e.g., How well hosts abide by Airbnb policies and procedures? Do hosts have ongoing effectiveness of service?) (Lu & Kandampully, 2016) • Privacy: It refers to the psychological zone to disclose personal and cultural values. Informational and physical privacy threats are important in Airbnb context (Lutz, Hoffmann, Bucher, & Fieseler, 2017). • Security: It refers to the state of being free from danger or threat. According to Yang and Ahn (2016), security in Airbnb‟s services is a more powerful antecedent of attitude toward Airbnb than significant dimensions of motivation toward SE, such as enjoyment and reputation. With that we will only elaborate on interpersonal security in Airbnb (i.e., between host and guest, not between guest and Airbnb). Conclusion SE is a fairly new and multi-disciplined field that covers open rooms for research, and specifically, Airbnb is one of the most prominent businesses in this context. The literature review presented underlies the infancy of well-grounded studies covering service quality perceptions of customers in SE. Seeking for additional dimensions from Airbnb guests‟ reviews is a novel research approach in studying customer engagement, and those dimensions shall be included in the research model. This research has certain limitations. Our perceived service quality conceptualization requires empirical validation to establish the boundaries of the construct. The guest reviews in Airbnb are subject to data quality issues. Also, reviews should contain substantial amount of words up to a certain threshold. Data collection from emerging world regions is rather tough since Airbnb is not widespread across those regions. Thus, US and European countries will be firstly taken into account, where the use of Airbnb is quite common. The study is expected to provide useful insights for TH practitioners and managers. It can underlie the factors that trigger customer engagement in this context. Cognitive/attitudinal factors are foreseen as the differentiators, which stand as the basis for service design and delivery.