The QLBS Model within the presence of feedback loops through the impacts of a large trader

We extend the QLBS model by reformulating via considering a large trader whose transactions leave a permanent impact on the evolution of the exchange rate process and therefore affect the price of contingent claims on such processes. Through a hypothetical limit order book we quantify the exchange rate altered by such transactions. We therefore define the quoted exchange rate process, for which we assume the existence of a postulated hedging strategy. Given the quoted exchange rate and postulated hedging strategy, we find an optimal hedging strategy through batch-mode reinforcement learning given the trader alters the course of the exchange rate process. We assume that the trader has its own concept of fair price and we define our problem as finding the hedging strategy with much lower transaction costs yet delivering a price that well converges to the fair price of the trader. We show our contribution results in an optimal hedging strategy with much lower transaction costs and convergence to the fair price is obtained assuming sensible parameters

MERKEZİ ISITMA SİSTEMLERİNDE ISINMA PROBLEMLERİ VE YAKIT PAYLAŞIMI

Bu çalışmada Isparta’da merkezi ısıtma sistemi kullanan konutlarda oturanların ısıtma sisteminden memnuniyetleri ve şikayetleri bir alan araştırması ile incelenmiştir. Yapılan çalışma sonucunda apartman sakinlerinin önemli bir kısmında çeşitli derecelerde ısıtma sisteminden memnuniyetsizlik gözlenmiştir. Isınma problemlerini azaltmak amacıyla daha adil bir paylaşım için tüketim temelli ölçme ve faturalandırma yapan ısı paylaşım sistemlerine de fazla sıcak bakılmadığı yapılan anket çalışması ile görülmüştür

The impact of artificial wall climbing as a recreational activity on children's locus of control

The aim of this research is to determine the effects of artificial wall climbing - which was performed by primary school students- as a recreative activity on children’s locus of control. Artificial wall climbing represents itself as a learning point beyond a sportive activity while creating an opportunity for participants to discover the limits of their own and that of others’, and opening a path for learning through experience by rendering the participants active rather than passive.The research was designed as one group pre-test – post-test model. The sample of the study is the same as the study population. 40 (15 female, 25 male) students studying in 7th and 8th grades of primary school attended voluntarily in this study.  Climbing practices were determined according to students' free time. Climbing practices were planned to be 90 minutes each. It is organized two days in a week between at least twenty-four hours. The test lasted 6 weeks in total. The activity which started with warm-up exercises suited for the age group was configured as a developmental schema as it started with top rope and extended to lead climbing route again on the climbing routes suited for the age groups. During the practice, it was ensured to provide knowledge and skills for not only climbing skills but also for other topics such as basic knowledge of climbing techniques, basic knots and belaying. The practice lasted six weeks and the questionnaire was applied before and after.To determine whether participants had a tendency towards externalizing or internalizing bias, "Nowicki-Strickland Locus of Control Scale" was used.As a result of the statistical analysis, it was observed that there are significant differences between pre-test and the difference of differences regarding the gender discrepancy and between pre-test and post-test scores regarding the total scores (p<0.05).The group of activities carried out for the artificial wall climbing led to a positive development in the children’s perception of locus of control and it was seen that children's beliefs on what’s happening around them is under their control and they can turn their lives in whichever direction they want were positively influenced

Pnömatik bir sistemin piston dinamiğinin deneysel modellenmesi

In this study, modelling and parameter identification for parameters of the piston dynamics are experimentally carried out on a pneumatic system, which consists of a magnetically coupled rodless cylinder with high precision guide, and electropneumatic proportional servovalves, magnetic linear scale, pressure sensors, analog anti-aliasing filters and interface circuits, through applying PRBS signals and acquiring the system responses as chamber pressures and piston position. Later the data are digitally processed to create input-output data for the identification model. First order linear velocity model of piston dynamics is obtained by using extended least squares method, parameter adaptation algorithm with decreasing gain for identification. The parametric model obtained is first converted into discrete-time state-space model. Then, the discrete state-space model is also converted into continuous-time state-space model. By comparing this model with mathematical motion equations of the system, viscous friction coefficients and mass quantity for the system are identified. Considering difficulties, even impossibilities, of determination of viscous friction coefficients by another way, the importance of the identification is obvious. In the simulation studies, realistic results can be obtained by using actual system parameters instead of assumed ones. And through watching the change of the system parameters by time, fault estimation can be performed and, ease of maintenance can be provided. Keywords: Experimental modelling, identification, pneumatic systemBu çalışmada; pnömatik bir sistemin piston dinamiği parametrelerinin, PRBS sinyalleri uygulanarak ve sistemin bu sinyallere silindir basınçları ve piston konumu olarak verdiği cevapları kullanarak, deneysel modelleme yapılarak tanılanması gerçekleştirilmektedir. Genişletilmiş en küçük kareler yöntemi azalan kazançlı parametre uyum algoritmasıyla kullanılarak birinci mertebe lineer piston hız modeli tanılanmıştır. Elde edilen ayrık zamanlı modelin sürekli zamanlı modele dönüştürülmesi ve matematiksel hareket denklemleriyle kıyaslanmasıyla sisteme ait kütle miktarı ve başka bir yöntemle bulunması güç olan viskoz sürtünme katsayısı bulunmuştur. Simülasyon çalışmalarında, sistem parametrelerinin belirli kabuller yerine gerçek değerlerinin kullanılmasıyla daha gerçekçi sonuçlar elde edilebilir. Yine parametre değerlerinin zamana göre değişimi incelenerek sistemde arıza tahmini yapılabilir, bakım kolaylıkları sağlanabilir. Anahtar Kelimeler: Deneysel modelleme, tanılama, pnömatik sistem

The Relationship between the Personality of Professional Tourist Guides and the Quality of Service Offered

As tourist guides have been recognized as tourism representatives, the impact of tourism on the perception of satisfaction and the intention of re-visiting has increased the research and development activities for the profession in recent years. The aim of the study is to determine whether there is a relationship between the personality traits and performance of professional tourist guides. In this context, determining how the performance level is perceived by tourists and determining how this performance is reflected in service quality. For this purpose, the Five Factor Personality Scale, which measures the personality traits, and the SERVPERF Scale, which measures the perceived service quality, were applied to 13 tourist guides and 475 tourists. As a result of the research, it was found that there was a significant relationship between the dimensions of personality traits and service quality. When the dimensions are examined, the perception of quality towards the dimension of concrete features expressing the external appearance of the tourist guides and the equipment used during the tour is negatively affected by the emotional stability (imbalance) and empathy characteristics of the tourist guides. As the extraversion personality of the tourist guide increases, the empathy that tourists perceive from the dimensions of service quality is unfavorable. It was observed that the perception of reliability, enthusiasm, trust and empathy of tourists was positively affected as the agreeableness (compatibility) increased. As the conscientiousness of professional tourist guides increases, the perception of reliability, trust and empathy perceived by the tourists towards the guides is positively affected. In this context, the number of samples can be increased in future studies and communication with more tourists and tourist guides can be provided.Turist rehberlerinin birer turizm temsilcisi olarak turistlerin memnuniyet algısı ve yeniden ziyaret etme niyeti üzerindeki etkisinin fark edilmesiyle beraber mesleğe yönelik yapılan araştırmalar ve bu alana yönelik geliştirme faaliyetleri artmıştır. Araştırmanın amacı profesyonel turist rehberlerinin kişilik özellikleri ile sergiledikleri performans arasında bir farklılaşma olup olmadığını belirlemektir. Bu kapsamda performans düzeyinin turistlerce nasıl algılandığını tespit ederek bu performansın hizmet kalitesine nasıl yansıdığını belirlemektir. Bu amaçla kişilik özelliklerini ölçen Beş Faktör Kişilik Ölçeği ve algılanan hizmet kalitesini ölçen SERVPERF Ölçeği, 13 turist rehberi ve 475 turiste uygulanmıştır. Araştırma neticesinde kişilik özellikleri boyutları ile hizmet kalitesi boyutları arasında anlamlı bir ilişki olduğu tespit edilmiştir. Boyutlar incelendiğinde turistlerin, turist rehberlerinin dış görünüşünü, tur esnasında kullandığı ekipmanlarını ifade eden somut özellikler boyutuna yönelik olan kalite algısı turist rehberlerinin duygusal denge (dengesizlik) ve empati özelliğine göre olumsuz yönde etkilenmektedir. Turist rehberinin dışa dönük kişilik özelliğinin arttıkça, turistlerin hizmet kalitesi boyutlarından algıladığı empati özelliği olumsuz yönde seyretmektedir. Bir diğer kişilik özelliği geçimlilik (uyumluluk) incelendiğinde bu özelliğin arttıkça turistlerin güvenilirlik, heveslilik, güven ve empati algısının olumlu yönde etkilendiği görülmüştür. Yine profesyonel turist rehberlerinin sorumluluk özelliği arttıkça turistlerin, rehberlere yönelik algıladığı güvenilirlik, güven ve empati algısı olumlu etkilenmektedir. Bu kapsamda gelecek çalışmalarda örneklem sayısının çoğaltılarak daha fazla turist ve turist rehberiyle iletişim sağlanabilir

Predicting Strict Trifecta Outcomes after Robot-Assisted Partial Nephrectomy: Comparison of RENAL, PADUA, and C-Index Scores

Nephrometry scores are designed to characterize tumors and stratify the surgical complexity. It remains unclear as to which nephrometry score can accurately predict the surgical outcomes. We aimed to assess the utility of radius, exophytic/endophytic, nearness, anterior/posterior, location (RENAL), preoperative aspects and dimensions used for anatomic classifications (PADUA), and centrality index (C-index) nephrometry scores for predicting the strict Trifecta achievement from a single institution series robotic-assisted partial nephrectomy (RAPN). We retrospectively identified the prospectively maintained robotic surgery database records of 91 patients who underwent RAPN between June 2015 and September 2020 in Antalya Training and Research Hospital. The main outcome of the study was the achievement of strict Trifecta (negative surgical margin, no major urologic complications, warm ischemia time ≤25 min, and ≥85% preservation of estimated glomerular filtration rate). A multivariable analysis was performed to identify the factors of strict Trifecta success. The mean patient age was 55.82 ± 13.37 years with a median clinical tumor size of 3.5 cm (IQR 2.5–4.9). The median RENAL, PADUA, and C-index score were 7(IQR 6–8), 8(IQR 7–10), and 2.01(IQR 1.64–2.72), respectively. A strict Trifecta could be achieved in 54 patients (59.3%). Clinical tumor size (P = 0.011), RENAL risk groups (low:reference; intermediate; P = 0.040; high; P = 0.009), PADUA risk groups (low:reference; intermediate; P = 0.044; high; P = 0.001) and C-index risk groups (low:reference; high; P = 0.015) were the independent predictors of strict Trifecta attainment in the multivariate analysis. None of the nephrometry scores were a superior predictor compared to other nephrometry scores in comparative analysis. RENAL, PADUA, and C-index scores were all independent predictors of a strict Trifecta achievement. Our comprehensive comparison of the three scores identified that none of the nephrometry scores proved to be inferior to others nephrometry scores

Outcomes of high-risk breast lesions diagnosed using image-guided core needle biopsy: results from a multicenter retrospective study

PURPOSEThe clinical management of high-risk lesions using image-guided biopsy is challenging. This study aimed to evaluate the rates at which such lesions were upgraded to malignancy and identify possible predictive factors for upgrading high-risk lesions.METHODSThis retrospective multicenter analysis included 1.343 patients diagnosed with high-risk lesions using an image-guided core needle or vacuum-assisted biopsy (VAB). Only patients managed using an excisional biopsy or with at least one year of documented radiological follow-up were included. For each, the Breast Imaging Reporting and Data System (BI-RADS) category, number of samples, needle thickness, and lesion size were correlated with malignancy upgrade rates in different histologic subtypes. Pearson’s chi-squared test, the Fisher–Freeman–Halton test, and Fisher’s exact test were used for the statistical analyses.RESULTSThe overall upgrade rate was 20.6%, with the highest rates in the subtypes of intraductal papilloma (IP) with atypia (44.7%; 55/123), followed by atypical ductal hyperplasia (ADH) (38.4%; 144/375), lobular neoplasia (LN) (12.7%; 7/55), papilloma without atypia (9.4%; 58/611), flat epithelial atypia (FEA) (8.7%; 10/114), and radial scars (RSs) (4.6%; 3/65). There was a significant relationship between the upgrade rate and BI-RADS category, number of samples, and lesion size Lesion size was the most predictive factor for an upgrade in all subtypes.CONCLUSIONADH and atypical IP showed considerable upgrade rates to malignancy, requiring surgical excision. The LN, IP without atypia, pure FEA, and RS subtypes showed lower malignancy rates when the BI-RADS category was lower and in smaller lesions that had been adequately sampled using VAB. After being discussed in a multidisciplinary meeting, these cases could be managed with follow-up instead of excision