2,269 research outputs found
Comparing clusterings and numbers of clusters by aggregation of calibrated clustering validity indexes
No full textAkhanli, Serhat Emre/0000-0001-7173-3277WOS: 000543319300001A key issue in cluster analysis is the choice of an appropriate clustering method and the determination of the best number of clusters. Different clusterings are optimal on the same data set according to different criteria, and the choice of such criteria depends on the context and aim of clustering. Therefore, researchers need to consider what data analytic characteristics the clusters they are aiming at are supposed to have, among others within-cluster homogeneity, between-clusters separation, and stability. Here, a set of internal clustering validity indexes measuring different aspects of clustering quality is proposed, including some indexes from the literature. Users can choose the indexes that are relevant in the application at hand. In order to measure the overall quality of a clustering (for comparing clusterings from different methods and/or different numbers of clusters), the index values are calibrated for aggregation. Calibration is relative to a set of random clusterings on the same data. Two specific aggregated indexes are proposed and compared with existing indexes on simulated and real data.EPSRCEngineering & Physical Sciences Research Council (EPSRC) [EP/K033972/1]The work of the second author was supported by EPSRC grant EP/K033972/1
Theory of mind and its relationship with alexithymia and quality of life in patients with psychogenic nonepileptic seizures: Comparisons with generalised epilepsy and healthy controls
No full textObjective: Psychogenic nonepileptic seizures (PNES) are associated with high alexithymia, social cognition problems and low quality of life (QoL). Theory of Mind (ToM) has been studied in several conditions as a significant predictor of QoL. We aimed to assess the relationship between ToM abilities, alexithymia and subjective QoL in PNES patients and compare with generalised epilepsy (ES) patients and healthy controls. Method: Patients with PNES (n = 28), ES (n = 28) and healthy volunteers (n = 28) were evaluated for alexithymia and quality of life (QoL) with Toronto Alexithymia Scale-20 (TAS-20) and Short Form-36 (SF-36). Reading the Mind in the Eyes test was used for assessment of affective ToM and Hinting Task and Strange Stories tests for cognitive ToM abilities. Results: Analyses revealed lower SF-36 scores and poorer ToM performance in the PNES group compared to healthy group and poorer cognitive ToM performance than ES group. Cognitive ToM performance was inversely correlated with TAS-20 difficulty identifying feelings subscale and physical functioning subscale of SF-36 in the PNES group. Conclusion: These results are consistent with previous research on PNES and other somatoform disorders and suggest that PNES is associated with impaired ToM task performance. ToM task performance might be related to specific aspects of alexithymia and QoL
Schneiderian symptoms and DSM 5: related to two cases
No full textThought to be more common in psychotic disorders in the past, Schneiderian symptoms (SS) were also observed in other disorders such as dissociative disorders and bipolar disorders. As a result of this, specific attribution of Schneiderian first rank symptoms was eliminated from diagnostic criteria of schizophrenia in DSM-5. In this article, we aim to present two cases having schneiderian symptoms. Since these cases had additional symptoms such as amnesia, fugue, and Schneiderian symptoms related to psychosocial stressors, we also suggested that these patients might have dissociative disorders. In terms of Schneiderian symptoms; instead of antipsychotic treatments, psychotherapeutic interventions and removal from psychogenic stressors can be considered in management of these cases. In DSM-5 the elimination of specific attribution of SS in psychosis results in clinician's drawn attention to this issue in other disorders. Therefore, this alteration may provide better diagnosis of dissociative disorders and bipolar disorders and prevent these patients' from taking high dose antipsychotic treatments unnecessarily
Retrospective Analysis of Zygomatic Implants for Maxillary Prosthetic Rehabilitation
No full textPurpose: The aim of this study was to evaluate 141 zygomatic implants for the reconstruction of severely atrophic maxillae. Materials and Methods: In this retrospective case series study, zygomatic implants were placed under general anesthesia. Inclusion criteria were as follows: ASA I or ASA II, age older than 18 years, inadequate bone for restoration with conventional implants, alternative augmentation procedures considered either inappropriate or contraindicated, absence of a medical condition related to implant failure, and providing written consent. Zygomatic implants used in the study consisted of three different brands: NobelZygoma, Southern Implants System, and Implantswiss. Results: The study included 45 patients, in whom 141 zygomatic implants were placed. The mean age of the patients was 51.76 (range: 23 to 72) years. Three patients were rehabilitated with removable prostheses, 19 patients with fixed prostheses, and 23 patients with hybrid prostheses. The overall complication rate was 5.67% (two zygomatic implants developed infection [1.4%], one zygomatic implant developed peri-implantitis [0.7%], three zygomatic implants developed sinusitis [2.1%], and two zygomatic implants showed unsuccessful prosthetic rehabilitation [1.4%]). The follow-up period ranged from 6 to 36 months. Conclusion: Clinical complications of zygomatic implants are acceptable, and their survival rates are similar to those of endosteal implants. Zygomatic implants can contribute to prosthetic rehabilitation
Performance of Ieee 802.11af Systems Under Realistic Channel Conditions
No full textAs the analog TV broadcasting channels have become less frequently used in the last decade there has been a great interest in these frequency bands for the deployment of regional local and personal area networks. Among them the local area network standard iEEE 802.11af denes PHY and MAC layer implementation of such networks in these unused frequency bands also named television white space (TVWS). According to the standard the systems may use contiguous or non-contiguous channels during their operation depending on the channel availability. Unlike perfectly known channel condition of iEEE 802.11af based systems used in the literature we investigate in detail the performance of different operation modes of these systems under realistic channel conditions. Accordingly we implement and compare the performances of perfectly known channel linear minimum mean-square error (LMMSE) estimator and a matching pursuit (MP) based channel estimator. MP based estimator being the more practical estimator compared to the others we assess how its performance approaches the other methods. According to simulation results MP-based channel estimation performance is found to be only 1-2 dB inferior compared to LMMSE-based estimation with known delays in low and medium SNR regions. Also the efects of guard interval rate channel resolution and separation of in-between bands in non-contiguous modes are tested in different scenarios. The results of thesis are important for practical implementation of iEEE 802.11af based systems.Analog televizyon yayın kanallarının son 10 yılda daha az sıklıkla kullanılması,
bölgesel yerle¸ isimlerinde bu frekans bantlarına büyük ilgi oluşturdu. Bunlar arasında,
yerel ağ standardı IEEE 802.11af bu tip kullanılmayan frekans bantları i¸cin, bir başka
ismiyle televizyon beyaz boşlukları için fiziksel ve ortam eri¸sim kontrollü katmanlarını
tanımlar. Standarda göre sistemler, biti¸sik veya biti¸sik olmayan bantları kanal durumuna göre kullanabilir. Literatürdeki mükkemmel bilinen kanal koşullarındaki IEEE
802.11af tabanlı sistemlerin aksine, bu tezde gerçek kanal koşulları altında, farklı operasyon modları ayrıntılı incelenmiştir. Buna göre, mükemmel bilinen kanalı, doğrusal
minimum ortalama karesel-hata kestirimini ve uyumlu arayış algoritmasını uyguladık
ve karşılaştırdık. Uyumlu arayış algoritması tabanlı kestirim, diğerine kıyasla daha
pratiktir. Bu algoritmanın performansının, diğer metodlara nasıl yaklaştığı değelendirilmiştir. Simülasyon sonuçlarına göre, uyumlu arayış algoritması, kanal gecikmesi bilinen
doğrusal minimum ortalama karesel-hata kestirim algoritmasıyla karşılaştırıldığında,
düşük ve orta işaret-g¨ur¨ult¨u-oranı bölgelerinde, yalnızca 1-2 dB performans kaybı yaşamaktadır. Bu çalışmada ayrıca koruyucu aralık oranı, kanal çözünürlülüğü ve ayrık
bantların arasındaki uzaklık gibi parametreler, farklı senaryolar altında test edilmiştir.
Tezin sonuçları IEEE 802.11af tabanlı sistemlerin pratik kurulumu için önemlidir
Özel Gereksinimli Çocuklarda Okul Öncesi Kaynaştırmaya Hazırlık Etkinlikleri
No full textOkul öncesi dönemdeki kaynaştırma uygulamalarını destekleyen çalışmalara bakıldığında, özel
gereksinimli küçük çocukların kaynaştırma ortamına yerleştirilmesinin avantajlarının fazla olduğu
görülmektedir. Okul öncesi dönemdeki kaynaştırma uygulamalarında üzerinde durulması gereken önemli
unsurlardan biri de kaynaştırmaya hazırlık becerileridir. Kaynaştırmaya hazırlık becerileri, ağırlıklı sosyal
duygusal beceriler olarak sıralanmakta ancak, akademik becerileri de kapsamaktadır. Kaynaştırma
uygulamasının başarıya ulaşabilmesi için kaynaştırmaya hazırlık becerilerinin belirlenmesi ve çocuklara
öğretilmesi gerekmektedir. Okul öncesi dönemdeki özel gereksinimli çocuğun kaynaştırma ortamına geçiş
sürecinde kaynaştırmaya hazırlık becerilerine sahip olmaması, kaynaştırma ortamına uyum sağlamasını
zorlaştırmaktadır. Dolayısıyla, bu becerilerin kaynaştırma ortamına geçmeden öğretilmesi ve süreç içinde
desteklenmesi gereklidir. Bu derleme çalışmasında okul öncesi dönemdeki kaynaştırmaya hazırlık
becerilerini tanıtmak ve öğretim süreçlerine ilişkin bilgi vermek amaçlanmıştır.When we look at the studies in support of preschool inclusion methods, we can see that the placement of young children with disabilities in an inclusive environment is advantageous. In methods oriented towards the inclusion of children in preschool, developing preparatory skills for inclusion is highly important. Preparatory skills for inclusion are mainly considered to be social-emotional skills, however they also include academic skills. For any inclusion effort to be successful, the associated preparatory skills must be determined and taught to children. Lack of inclusion preparatory skills in children of preschool age with disabilities when they are just about to transition into this environment will make it difficult for them to harmonize within an environment conducive to inclusion. Therefore these skills are required to be taught prior to the transition into the inclusive environment, but also reinforced during the process. This review study aims to introduce some of the preparatory skills for inclusion in the preschool period, as well as to provide information pertaining to the educational processe
Coexistence of Cognitive Radio Based Networks in Tv White Space
No full textDue to increasing data rates in enhancing wireless communications RF spectrum which is one of the most crucial natural sources has become more valuable. in order to utilize the limited spectrum e_ciently and solve the scarcity problem regulatory agencies granted unlicensed networks or secondary users (SUs) access to licensed bands for wireless communication with the condition that they should not cause harmful interference to primary users (SUs). Cognitive radio (CR) technology enables devices to access the spectrum opportunistically. Using CR based networks licensed bands can be utilized more e_ectively for wireless communications. TV White Space (TVWS) refers to portions of the RF spectrum that was reserved only for licensed terrestrial TV broadcasting and is opened to unlicensed use under regulatory conditions. While regulations protect licensed systems in TVWS from harmful interference interference prevention among unlicensed systems is left mainly to manufacturers. Consequently there is a need to develop new coexistence approaches between TVWS networks. Busy tone broadcasting is a coexistence method which can be used by TVWS networks to announce that the selected frequency band is occupied. in this dissertation a busy tone based coexistence algorithm is proposed for wireless local area networks (WLANs) operating in TVWS (i.e. iEEE 802.11af based networks) where wireless regional area network (WRAN) (i.e. iEEE 802.22 based network) is assumed to be the busy tone broadcaster. The proposed algorithm is analyzed in detail considering the e_ects of log-normal shadowing client distribution around the access point and the number of clients where exact interfering packet rate and successful packet transmission rate expressions are obtained and validated by simulations for di_erent scenarios. The results show that with the proposed coexistence approach a WLAN can reliably detect the busy tone signal to change its frequency band and can reduce interference to WRAN. Even if there is no available frequency band for the WLAN the WRAN still maintains its enhanced successful packet transmission performance. The deployment of the proposed algorithm is important for successful coexistence between cognitive wireless regional and local area networks where interference among networks is not regulated such as in TVWS bands.En önemli doğal kaynaklardan biri olan RF tayfı, gelişen kablosuz haberleşmelerdeki artan veri hızları sebebiyle daha da önemli hale gelmiştir. Bu kısıtlı tayfı daha verimli kullanmak ve kıtlık sorununu çözmek için, düzenleyici kurumlar lisanssız ağlara ya da ikincil kullanıcılara (SUs), birincil kullanıcılara zararlı olacak girişim yaratmamaları koşuluyla lisanslı bantlara erişip kablosuz haberleşme yapabilmeleri için onay vermiştir. Bilişsel radyo (CR) teknolojisi aygıtların tayfa fırsatçı bir şekilde erişebilmelerini sağlar. CR tabanlı ağları kullanarak, lisanslı bandlar kablosuz haberleşme için daha verimli bir şekilde kullanılabilinir. TV Beyaz Boşluğu (TVWS) önceden sadece lisanslı karasal TV yayınlarına ayrılmış ve şimdi de düzenlemeler altında ikincil kullanıcıların da kullanımına açılmış tayfı kastetmektedir. Düzenlemeler TVWS'te bulunan lisanslı kullanıcıları zararlı girişimlerden korurken, lisanssız kullanıcılar arasındaki girişimi önleme daha çok üreticilere bırakılmıştır. Bu nedenle, TVWS ağları arasında yeni bir birlikte varolma yaklaşımına ihtiyaç vardır. Birlikte varolma metotlarından biri olan meşgul tonu (BT) yayınımı, TVWS ağları tarafından seçilen frekans bandının dolu olduğunu haber vermek için kullanılabilinir. Bu tezde, TVWS bandında çalışan kablosuz yerel alan ağı (WLAN) (ör: IEEE 802.11af ağı) için meşgul tonu tabanlı bir birlikte varolma algoritması önerilmiş ve kablosuz bölgesel alan ağının (WRAN) (ör: IEEE 802.22 ağı), meşgul tonu yayıncısı olduğu var sayılmıştır. Önerilen algoritma, log-normal gölgeleme etkisini, erişim noktası etrafındaki kullanıcı dağılımlarını, ve kullanıcı sayılarını dikkate alarak detaylı bir şekilde analiz edilmiş, girişim yapan paket oranı ve başarılı paket gönderme oranı için kesin ifadeler bulunup, doğrulukları da farklı senaryolarda simülasyonlar ile onaylanmıştır. Sonuçlar göstermektedir ki, önerilen birlikte varolma yaklaşımı ile WLAN güvenilir bir şekilde meşgul tonunu fark edip, frekans bandını değiştirebilir ve WRAN'a yapılan girişimi azaltabilir. WLAN için uygun frekans bandı olmasa dahi, WRAN iyileştirilmiş paket gönderim performansını sürdürmeye devam edebilir. Önerilen algoritmanın uygulanması TVWS bandları gibi girişimin düzenlenmediği bilişsel kablosuz bölgesel ve yerel alan ağlarının başarılı bir şekilde birlikte varolabilmeleri için önemlidir
Modelling of excitation and response induced by impact : an investigation for slamming of mono- and multi-hulled vessels
No full textWaves, winds and currents can cause specific environmental effects that a marine structure has to withstand. Amongst these, wave action is the fundamental source of load on the marine structure. In order to ensure safety, operability, economy and design-life duration of a marine structure, theoretical estimates of wave loads and structural response play an increasingly important role in the overall design process. The interaction between a structure and a fluid medium is of great concern in numerous engineering problems, e.g., slamming of ships in rough seas, vibration of water retaining structures under earthquake loading etc. All these dynamic problems include the interaction, which takes place between the structure and surrounding fluid. It is of practical importance to estimate the effect of the induced fluid loading on the dynamic state of the vibrating structure. If the vibration takes place in a relatively low-density fluid, such as air, in comparison with the structural material, in most situations, the loading will have a comparatively small influence on the vibration. However, when the vibrating structure is in contact with a fluid which has a comparable density, such as water, the fluid loading which depends on the structural surface motions will significantly alter the dynamic state of the structure from that of the in vacuo vibration. In other words, the equations of structural and fluid motions are inexorably linked. Therefore, development, improvement and application of numerical techniques for analyzing such an interaction become one of the most important activities of naval architecture researchers. The following document is about the interaction mentioned above and particularly studied on the slamming issue and its main characteristic, transient excitation and response. A dry analysis is presented on simple beams, idealized SWATH ship as a preamble to a future wet deck slamming analysis and plates (unstiffened and stiffened). As the basis of subsequent harmonic and transient analyses, modal characteristics of each system is studied and in conjunction with the results obtained from these, responses on frequency and time domain are calculated in this document. In the following part of the thesis beams and plates are analysed under transient excitation, since this is the basis for modelling the excitation and response induced by slamming. Results are produced and compared both using theoretically established convolution method and ANSYS (transient analysis with full and mode superposition methods). Realistic stiffened plates and their equivalent flat plates are also studied and analysed in the subsequent sections. Difficulties encountered during the structural modelling (finite element modelling) are briefly outlined, with particular emphasis to the importance of the selection of appropriate finite elements.</p
Clinical and laboratory investigations on cervical margin relocation
No full textIn the presence of subgingival proximal margins, close to or below the cemento-enamel junction (CEJ), impression taking and adhesive luting procedures for indirect restorations are hampered; surgical crown lengthening or orthodontic eruption are viable options. However, the placement of a small amount of composite, so-called cervical margin relocation (CMR), was proposed as an alternative technique.
To date, literature about CMR is scarce and the aim of this PhD thesis was to perform laboratory and clinical investigations to shed light on some crucial missing points.
The thesis consists of 5 studies. The first study is a literature review summarizing the existing scientific literature on CMR technique performed prior to the adhesive cementation of indirect restorations. The second study is an in vivo randomized controlled clinical trial assessing the possible influence of CMR on periodontal health, after 12- month of clinical service. The third study is an in vitro study evaluating the marginal sealing of relocated mesio-occluso-distal overlays. The fourth study is an in vitro study analyzing the influence of cervical margin relocation and adhesive system on microleakage of indirect composite restorations. The fifth study is an in vitro study evaluating the possible correlation between two methodological approaches applied to evaluate cervical margin relocation.
Different methodological approaches were used to perform the above-reported investigations, such as scanning electron microscopy (SEM) and microleakage analyses.
The principal investigator was calibrated and trained before performing the operative procedures and laboratory investigations. All the recorded data were statistically analyzed with dedicated software.
CMR is a relatively new restorative procedure and information on its performance is limited. Within the limitations of the performed laboratory and clinical studies, the present PhD thesis allowed to draw the following conclusions:
1. On the basis of the reviewed literature, currently, there is no strong scientific evidence that could either support or discourage the use of CMR technique prior to restoration of deep subgingival defects with indirect adhesive restorations; further randomized controlled clinical trials are necessary to provide reliable evidence on the influence of CMR technique on the clinical performance, especially on the longevity of restorations and periodontal health.
2. A higher incidence of bleeding on probing can be expected around teeth treated with CMR and in coincidence with deep margins placed at or closer than 2 mm from the bone crest; consequently, CMR should be considered as a clinically sensitive-technique, especially when performed on deep subgingival margins.
3. The marginal sealing ability of flowable and microhybrid resin composites is comparable for CMR; furthermore, luting overlays directly onto dentin without CMR appears to be a better method for limiting marginal leakage underneath CAD/CAM overlays.
4. CMR technique and the adhesive system employed for luting indirect restorations might represent a significant factor affecting microleakage at the interface below CEJ.
5. CMR seems to provide less adequate seal of the margin than the one achieved by cementing the restoration directly to dentin without CMR. The sealing ability of the marginal interface depends on the adhesive materials used for performing CMR. Differences in the quality of the marginal adaptation between two different materials used for CMR could not be detected by SEM observations. SEM examination of the marginal adaptation does not allow for the predictions of the functional sealing of the margins.
Future in vitro and in vivo studies should evaluate the effectiveness of CMR technique and the marginal seal of different bonding systems and luting cements in combination with CMR. Particularly, randomized controlled clinical trials should investigate the durability of CMR and the response of periodontal tissues
Scma Kod Kitabı Tasarımı Yaklaşımları
No full textIn 4G systems, Orthogonal Frequency-Division Multiple Access (OFDMA) has been used conventionally for multiple access purposes. This technique has low spectral efficiency since it allocates the resources orthogonally to each user. As an alternative to this technique, Non-orthogonal Multiple Access (NOMA) has been proposed for new generation 5G systems as it allows different users to use the same resources and therefore, increases spectral efficiency. Sparse Code Multiple Access (SCMA) is a code-based NOMA technique and its performance depends on codebook design. In this thesis, four different approaches are proposed by examining the design of the conventional codebook, which is widely used in SCMA studies in the literature. In the first approach, the distances between the constellation set points have been increased while the total energy remains constant. In the second approach, the angle between the constellation set points on the sub-carriers in the codebook has been equally set. In the third approach, by applying the permutation method, it has been aimed to reduce the complexity in the codebook by multiplying the constellation set points on the first and second sub-carriers with the halfangle formula. In the fourth approach, a new constellation set points with the energy remaining constant has been designed. Considering the four different design approaches, the conventional codebook has been modified. Simulation results have shown that 1-2dB gain can be achieved using different design approaches in the high signal-to-noise-ratio (SNR) region.4G sistemleri geleneksel olarak Dikgen Frekans-Bölmeli Çoklu Erişim (Orthogonal Frequency-Division Multiple Access, OFDMA) tekniğini kullanırlar. Bu yöntemde her kullanıcıya kendisine ait bir kaynak tahsis edildiğinden spektral verimliliği düşüktür. Bu duruma alternatif olarak geliştirilen ve yeni nesil 5G sistemler için düşünülen Dikgenolmayan Çoklu Erişim (Non-orthogonal Multiple Access, NOMA) tekniği, farklı kullanıcıların aynı kaynakları kullanmasına izin verir ve böylece spektral verimlilik artırılır. NOMA'nın kod tabanlı yaklaşımı olan Seyrek Kodlu Çoklu Erişim (Sparse Code Multiple Access, SCMA) tekniğinin performansı kod kitabı tasarımına bağlıdır. Bu tez çalışmasında, literatürdeki SCMA çalışmalarında yaygın bir şekilde kullanılan geleneksel kod kitabının tasarımı incelenerek dört farklı yaklaşım önerilmiştir. Birinci yaklaşımda enerjsi sabit kalacak şekilde işaret kümesi noktaları arasındaki uzaklıklar artırılmıştır. İkinci yaklaşımda kod kitabındaki alt taşıyıcılarda bulunan işaret kümesi noktaları arasındaki açılar eşit olarak ayarlanmıştır. Üçüncü yaklaşımda permutasyon yöntemi uygulanarak, birinci ve ikinci alt taşıyıcıda bulunan işaret kümesi noktalarını yarım açı formülü ile çarparak kod kitabındaki karmaşıklığın azaltılması hedeflenmiştir. Dördüncü yaklaşımda ise enerjisi sabit kalacak şekilde yeni bir işaret kümesi noktaları tasarımı önerilmiştir. Özetle, dört farklı tasarım yaklaşımı kullanılarak yaygın olarak kullanılan kod kitabı modifiye edilmiştir. Benzetim çalışmaları göstermektedir ki yüksek işaret gürültü oranı (signal-to-noise-ratio, SNR) bölgesinde kullanılan yaklaşıma bağlı olarak 1-2dB'lik kazanç elde edilebilmektedir
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