A novel distributed scheduling scheme for OFDMA uplink using channel information and probabilistic transmission

Distributed uplink scheduling in OFDMA systems is considered. In the proposed model, mobile terminals have the responsibility of making their own transmission decisions. The proposed scheme is based on two dimensional reservation in time and frequency. Terminals use channel state information in order to favor transmissions over certain subchannels, and transmission is done in a probabilistic manner. The proposed approach provides more autonomy to mobile devices in making transmission decisions. Furthermore, it allows avoiding collisions during transmission since it leads to collision detection during the resource reservation phase. The proposed approach is compared to other random access methods and shown to be superior in terms of increasing sum-rate, reducing the number of users in outage, and reducing the collision probability in the reservation phase.     

New Beta-lactamases in Candidate Phyla Radiation: Owning Pleiotropic Enzymes Is a Smart Paradigm for Microorganisms with a Reduced Genome

The increased exploitation of microbial sequencing methods has shed light on the high diversity of new microorganisms named Candidate Phyla Radiation (CPR). CPR are mainly detected via 16S rRNA/metabarcoding analyses or metagenomics and are found to be abundant in all environments and present in different human microbiomes. These microbes, characterized by their symbiotic/epiparasitic lifestyle with bacteria, are directly exposed to competition with other microorganisms sharing the same ecological niche. Recently, a rich repertoire of enzymes with antibiotic resistance activity has been found in CPR genomes by using an in silico adapted screening strategy. This reservoir has shown a high prevalence of putative beta-lactamase-encoding genes. We expressed and purified five putative beta-lactamase sequences having the essential domains and functional motifs from class A and class B beta-lactamase. Their enzymatic activities were tested against various beta-lactam substrates using liquid chromatography-mass spectrometry (LC-MS) and showed some beta-lactamase activity even in the presence of a beta-lactamase inhibitor. In addition, ribonuclease activity was demonstrated against RNA that was not inhibited by sulbactam and EDTA. None of these proteins could degrade single- and double-stranded-DNA. This study is the first to express and test putative CPR beta-lactamase protein sequences in vitro. Our findings highlight that the reduced genomes of CPR members harbor sequences encoding for beta-lactamases known to be multifunction hydrolase enzymes.     

Enhanced fair earliest due date first scheduling strategy for multimedia applications in LTE downlink framework

Guaranteeing a certain delay threshold for delay‐sensitive applications in long term evolution (LTE) cellular communication system is a very challenging mission. By implementing an optimal scheduling strategy, this mission will be achieved. In this article, a novel scheduler is introduced in order to meet a predefined level of service quality by guaranteeing a specific delay threshold for delay‐sensitive applications in LTE cellular systems. The proposed scheduler assigns the available resource blocks (RBs) to active user equipments (UEs) tacking into consideration several attributes. The expiration date of each packet, the channel quality, the average data rate previously achieved by each UE, and the number of dropped packets for each UE compared with the average number of packets totally dropped are all considered in the proposed scheduler working mechanism. Consequently, the proposed scheduling strategy reduces the number of packets dropped for multimedia applications, and at the same time maximizes the overall throughput of the network. Simulation results are provided to study and evaluate the performance of the proposed scheduling strategy. A comparative study is presented between the proposed strategy and the most recent scheduling techniques. The obtained results prove that the proposed scheduling strategy has considerably acceptable and appreciated results compared with the results of the state‐of‐the‐art scheduling techniques.     

Hybrid Paper–Plastic Microchip for Flexible and High‐Performance Point‐of‐Care Diagnostics

A low‐cost and easy‐to‐fabricate microchip remains a key challenge for the development of true point‐of‐care (POC) diagnostics. Cellulose paper and plastic are thin, light, flexible, and abundant raw materials, which make them excellent substrates for mass production of POC devices. Herein, a hybrid paper–plastic microchip (PPMC) is developed, which can be used for both single and multiplexed detection of different targets, providing flexibility in the design and fabrication of the microchip. The developed PPMC with printed electronics is evaluated for sensitive and reliable detection of a broad range of targets, such as liver and colon cancer protein biomarkers, intact Zika virus, and human papillomavirus nucleic acid amplicons. The presented approach allows a highly specific detection of the tested targets with detection limits as low as 10² ng mL^?1 for protein biomarkers, 10³ particle per milliliter for virus particles, and 10² copies per microliter for a target nucleic acid. This approach can potentially be considered for the development of inexpensive and stable POC microchip diagnostics and is suitable for the detection of a wide range of microbial infections and cancer biomarkers.     

High-voltage DMOS integrated circuits using floating-gate protection technique

An efficient low power protection scheme for thin gate oxide of high voltage (HV) DMOS transistor is presented. To prevent gate-oxide breakdown and protect HV transistor, the voltage controlling its gate must be within 5 V from the HV supply. Thus signals from the low voltage domain must be level shifted to control the gate of this transistor. Usually this level shifting involves complex circuits that reduce the speed besides requiring of large power and area. In this paper, a simple and efficient protection technique for gate-oxide breakdown is achieved by connecting a capacitor divider structure to the floating-gate node of HV transistor to increase its effective gate oxide thickness. Several HV circuits, including: positive and negative HV doublers and level-up shifters suitable for ultrasound sensing systems are built successfully around the proposed technique. These circuits were implemented with 0.8 μm CMOS/DMOS HV DALSA process. Simulation and experimental results prove the good functionality of the designed HV circuits using the proposed protection technique for voltages up to 200 V.     

1-V DTMOS-Based Class-AB Operational Amplifier: Implementation and Experimental Results

In this paper, we describe a novel low-voltage class-AB operational amplifier (opamp) based on dynamic threshold voltage MOS transistors (DTMOS). A DTMOS transistor is a device whose gate is tied to its bulk. DTMOS transistor pseudo-pMOS differential input pairs are used for input common-mode range enhancement, followed by a single ended class-AB output. Two versions of the proposed opamp (opamp-A and opamp-B) were fabricated in a standard 0.18-mum CMOS process technology. Measurements under 5 pF and 10 kOmega load conditions gave, for opamp-A, a DC open-loop gain of 50.1 dB, and a unity gain bandwidth (GBW) of 26.2 MHz. A common-mode rejection ratio (CMRR) of 78 dB, and input and output swings of 0.7 V and 0.9 V, respectively, were achieved. Opamp-B has been optimized for biomedical applications, and is implemented to build the analog front-end part of a near-infrared spectroreflectometry (NIRS) receiver of a multi-wavelength wireless brain oxymeter apparatus. A DC open-loop gain of 53 dB, a GBW of 1.3 MHz, and input and output swings of 0.6 V and 0.8 V, respectively, were measured. Opamp-A consumes 550 muW with an input referred noise of 160 nV/radicHz at 1 kHz. Opamp-B consumes only 40 muW and exhibits a lower input referred noise of 107 nV/radicHz at 1 kHz     

A background calibration technique for multibit/stage pipelined and time-interleaved ADCs

A digital background calibration technique to compensate for the nonlinearity and gain error in the sub-digital-to-analog converter (SDAC), and the operational amplifier finite dc gain in multibit/stage pipelined analog-to-digital converter (ADC) is proposed. By injecting subtractive calibration voltages in a modified conventional multibit multiplying DAC and performing correlation based successive coefficient measurements, a background calibration is performed. This calibration technique does not need an accurate reference voltage or an increasing in the SDAC resolution. A global gain correction essential for time-interleaved ADCs is presented. Simulation results show that in the presence of realistic capacitor and resistance mismatch and finite op-amp gain, this technique improves the linearity by several bits in single and multi-channel pipelined ADC.     

New evolution in two-way relay networks based on physical layer network coding

Telecommunication Systems - In this paper, a physical-layer network coding (PNC) method is offered for a two-way relay network with spatial modulation (SM) for source node and relay node. For this...