A Low Complexity Space-Time Block Codes Detection for Cell-Free Massive MIMO Systems

The new generation of telecommunication systems must provide acceptable data rates and spectral efficiency for new applications. Recently massive MIMO has been introduced as a key technique for the new generation of telecommunication systems. Cell-free massive MIMO system is not segmented into cells. Each BS antennas are distributed throughout the environment and each user is served by all BSs, simultaneously. In this paper, the performance of the multiuser cell-free massive MIMO-system exploying space-time block codes in the uplink, and with linear decoders is studied. An Inverse matrix approximation using Neumann series is proposed to reduce the computational and hardware complexity of the decoding in the receiver. For this purpose, each user has two antennas, and also for improving the diversity gain performance, space-time block codes are used in the uplink. Then, Neumann series is used to approximate the inverse matrix in ZF and MMSE decoders, and its performance is evaluated in terms of BER and spectral efficiency. In addition, we derive lower bound for throughput of ZF decoder. The simulation results show that performance of the system , in terms of BER and spectral efficiency, is better than the single-antenna users at the same system. Also, the BER performance in a given system with the proposed method will be close to the exact method.Comment: 5 pages, 4 figures, Accepted for ICEE202

Platelet clearance via shear-induced unfolding of a membrane mechanoreceptor

Mechanisms by which blood cells sense shear stress are poorly characterized. In platelets, glycoprotein (GP)Ib-IX receptor complex has been long suggested to be a shear sensor and receptor. Recently, a relatively unstable and mechanosensitive domain in the GPIba subunit of GPIb-IX was identified. Here we show that binding of its ligand, von Willebrand factor, under physiological shear stress induces unfolding of this mechanosensory domain (MSD) on the platelet surface. The unfolded MSD, particularly the juxtamembrane € Trigger' sequence therein, leads to intracellular signalling and rapid platelet clearance. These results illustrate the initial molecular event underlying platelet shear sensing and provide a mechanism linking GPIb-IX to platelet clearance. Our results have implications on the mechanism of platelet activation, and on the pathophysiology of von Willebrand disease and related thrombocytopenic disorders. The mechanosensation via receptor unfolding may be applicable for many other cell adhesion receptors

Predicting the Occurrence of Natural Fires in Forests and Ranges using Artificial Neural Networks (Case Study: Zagros Region, Izeh Township)

There is no doubt that climatic factors are one of significant parameters in occurrence of natural fires in forest and range ecosystems. The goal of this study was a monthly-based prediction of the occurrence of the natural fires using artificial neural networks in Izeh, north-west of Khuzestan province. The natural fire occurrence data including date of the occurrence, the burned area and number of the fire occurrence was obtained from Izeh Natural Resources Office. The findings indicated that the algorithm of multiple layer perceptron and hyperbolic function were efficient in exploring the relationship between climatic factors and the natural fire occurrence. The networks with two hidden layers and 15 neurons have revealed high accuracy in prediction of the natural fires occurrence. Moreover, for prediction step FMSE(Final Mean Square) was recorded 0.0038. While for testing step, coefficient of variation, MSE(Mean Square), and NMSE(Normal Mean Square) were equal to 0.99, 0.073, and 0.018, respectively. For validation step, the trained network has indicated a high determination coefficient (r2=0.98) between the observed and predicted values. It should be mentioned that the present approach in this study could achieve an artificial neural network with medium performance (r2=0.58) between climate data and the burned area of the natural fire

Accommodation of Arabia-Eurasia convergence in the Zagros-Makran transfer zone, SE Iran: A transition between collision and subduction through a young deforming system

International audienceAt Iranian longitude, the Arabian plate is moving northward relative to Eurasia (∼20 mm yr-1 according to GPS). To the east, this relative motion is accommodated by northward subduction under the E-W Makran emerged accretionary prism. To the west, it is accommodated partly by the Zagros fold-and-thrust belt and partly by the Alborz/Kopet Dagh deforming zones further north. This work investigates the NNW striking transition zone that connects Zagros and Makran: the Minab-Zendan fault system. Satellite images, and structural and geomorphic field observations show a distributed deformation pattern covering a wide domain. Five north to NW trending major faults were identified. They exhibit evidence for late Quaternary reverse right-lateral slip, and correspond to two distinct fault systems: the western one transferring the Zagros deformation to the Makran prism, and the eastern one northward transferring the deformation to the Alborz/Kopet Dagh. Tectonic study and fault slip vector analyses indicate that two distinct tectonic regimes have occurred successively since the Miocene within a consistent regional NE trending compression: (1) an upper Miocene to Pliocene tectonic regime characterized by partitioned deformation, between reverse faulting and en echelon folding; (2) a NE trending σ1 axis transpressional regime homogeneously affecting the region since upper Pliocene. The change is contemporaneous with major tectonic reorganization regionally recorded. Therefore this study provides evidence for active deformation that is not localized, but distributed across a wide zone. It accommodates the convergence and transfers it from collision to subduction by transpressional tectonics without any partitioning process in the present-day period

Trustworthy 100-Year Digital Objects: Evidence Even After Every Witness is Dead

How can a publisher store digital information so that any reader can reliably test its authenticity, even years later when no witness can vouch for its validity? What is the simplest security infrastructure sufficient to protect and later test evidence of authenticity? In ancient times, wax seals impressed with signet rings were affixed to documents as evidence of their authenticity. A digital counterpart is a message authentication code fixed firmly to each important document. If a digital object is sealed together with its own audit trail, each user can examine this evidence to decide whether to trust the content—no matter how distant this user is in time, space, and social affiliation from the document’s source. We suggest technical means for accomplishing this: encapsulation of the document content with metadata describing its origins, cryptographic sealing, webs of trust for public keys rooted in a forest of respected institutions, and a certain way of managing document identifiers. These means will satisfy emerging needs in civilian and military record management, including medical patient records, regulatory records for aircraft and pharmaceuticals, business records for financial audit, legislative and legal briefs, and scholarly works. This is true for any kind of document, independently of its purposes and of most data type and representation details, and provides each user with autonomy for most of what he does. Producers can prepare works for preservation without permission from or synchronization with any authority or service agent. Librarians can add metadata without communicating with document originators or repository managers. Consumers can test authenticity without Internet delays, apart from those for fetching cryptographic certificates. Our method accomplishes much of what is sought under labels such as “trusted digital repositories”, and does so more flexibly and economically than any method yet proposed. It requires at most easy extensions of available content management software, and is therefore compatible with what most digital repositories have installed and are using today.