RECEIVED SNR BASED CODE AND ANTENNA/RELAY SELECTION FOR LIMITED FEEDBACK COMMUNICATION

Sınırlı geribeslemeli çok-girdili çok-çıktılı (ÇGÇÇ) haberleşme sisteminde kod seçimi ve verici anten seçimi yaygın olarak kullanılır. Eğer vericideki bir antenin kanal kazancı diğer antenlerin kanal kazançlarına göre çok büyükse verici anten seçimi kullanmak alıcıdaki Sinyalin Gürültüye Oranı (SGO)'nı artırır. Buna karşılık, vericideki antenlerin kanal kazançları birbirlerine yakın değerlerde ise kod seçimi kullanmak alıcıdaki SGO'yu arttırır. Bu makalede, ÇGÇÇ haberleşmesinde alıcıdaki SGO'yu arttırmak için uyarlamalı kod ve anten seçimi önerilmiştir. Bu teknikte, fazladan bir bitlik geribesleme kullanılarak verici anten seçimine ve kod seçimine göre alıcıda daha iyi bir SGO değeri elde edilir. Detaylı benzetimler göstermiştir ki, üç verici anten için uyarlamalı kod ve anten seçiminde kullanılacak 4 bitlik geribesleme, kod seçimi olarak kullanılan genişletilmiş dengeli uzay-zaman blok kodlamanın ideal geribesleme başarımını elde etmektedir. İdeal geribesleme ise kanal durum bilgisinin vericide tam olarak bilinmesini gerektirir. Ayrıca, önerilen teknik işbirlikli haberleşmeye uygulanmış ve benzer başarım artışı sağlanmıştır. Önerilen tekniğin ÇGÇÇ ile işbirlikli haberleşmesine uygulanmasındaki fark, anten seçimi yerine röle seçiminin yapılmasıdır. Code selection and transmit antenna selection are widely used in limited feedback multi input multi output (MIMO) communication system. When one of the antenna channel gains is much higher than the other antenna channel gains; using antenna selection method increases received Signal-to-Noise Ratio (SNR) at the receiver. However, when antenna channel gains are close to each other; using code selection method increases the received SNR at the receiver. In this paper, we propose an adaptive code and antenna selection scheme to increase the received SNR at the destination for MIMO system. In this technique, using one additional feedback bit yields improved SNR at the destination compared to using solely code or transmit antenna selection method. Detailed simulations show that adaptive code and antenna selection with four bit feedback yields a performance of the extended balanced space-time block coding with ideal feedback which requires exact channel state information at the transmitter. In addition, the proposed technique is applied into the cooperative communication and similar performance improvement is observed. The difference between MIMO and cooperative communication is using relay selection instead of antenna selection

“Return of the repressed”: Exposure to police violence increases protest and self-sacrifice intentions for the Yellow Vests

Worldwide, it is not uncommon to observe violent police reactions against social movements. These are often rationalized by decision makers as efficient ways to contain violence from protesters. In France for instance, the ongoing Yellow Vests protests have generated an unprecedented number of casualties, injuries, and convictions among protesters. But was this response efficient in diminishing violence stemming from the Yellow Vests? To this day, little is known about the psychological consequences of police violence in the context of protests. Combining insights from Significance Quest Theory and the Social Identity perspective on collective action, we predicted that exposure to police violence could “backfire” and lead to increased radicalization of protesters. A cross-sectional investigation of 523 Yellow Vests yielded evidence for this hypothesis. We found positive direct effects of exposure to police violence on intentions to attend future demonstrations and to self-sacrifice for the Yellow Vests. Moreover, these effects were serially mediated by perceived Loss of Significance and Identification with the Yellow Vests. Paradoxically, these results highlight for the first time the mechanism through which political repression may contribute to the formation of radical politicized identities. Thus, we recommend that decision makers privilege the use of de-escalation techniques in protest policing whenever possible. </jats:p

Inverse Layer Dependence of Friction on Chemically Doped MoS_{2}

We present the results of atomic-force-microscopy-based friction measurements on Re-doped molybdenum disulfide (MoS2). In stark contrast to the seemingly universal observation of decreasing friction with increasing number of layers on two-dimensional (2D) materials, friction on Re-doped MoS2 exhibits an anomalous, i.e. inverse dependency on the number of layers. Raman spectroscopy measurements revealed signatures of Re intercalation, leading to a decoupling between neighboring MoS2 layers and enhanced electron-phonon interactions, thus resulting in increasing friction with increasing number of layers: a new paradigm in the mechanics of 2D materials.Comment: 15 pages incl. Supplemental Material, 5 figure

ANKOS publisher application system and its impact on the e-resource evaluation process

The Publisher Application System (PAS) is a Web-based archiving and online evaluation system developed by the Database Evaluation Group (DEG), one of the working groups formed within the Anatolian University Libraries Consortium (ANKOS). The DEG was formed in 2008 to inquire and evaluate e-resources suited to the needs of the consortium; to follow up similar consortial activities worldwide as well as developments in connection with the scientific publishing industry; and to determine, implement, and improve pricing models in accordance with the prevailing economic, legal, and academic system. Development of the PAS was essential to ensure standardization and sustainability towards a more detailed and effective analysis of e-resources qualifying for evaluation by ANKOS. The PAS played an important part not only in establishing and defining the workflow of the DEG, but also in creating an archive of both the e-resources submitted to the consortium and the applicant publishers/agents submitting these resources. This article outlines the process that started with the foundation of the DEG through the formation of the PAS as well as the present setup of the system. It is also hoped that this case study will have a positive contribution to the processes being followed by the persons and the groups engaged in similar activities.pre-prin