32 research outputs found
Cooperative Algorithms for MIMO Amplify-and-Forward Relay Networks
Interference alignment is a signaling technique that provides high
multiplexing gain in the interference channel. It can be extended to multi-hop
interference channels, where relays aid transmission between sources and
destinations. In addition to coverage extension and capacity enhancement,
relays increase the multiplexing gain in the interference channel. In this
paper, three cooperative algorithms are proposed for a multiple-antenna
amplify-and-forward (AF) relay interference channel. The algorithms design the
transmitters and relays so that interference at the receivers can be aligned
and canceled. The first algorithm minimizes the sum power of enhanced noise
from the relays and interference at the receivers. The second and third
algorithms rely on a connection between mean square error and mutual
information to solve the end-to-end sum-rate maximization problem with either
equality or inequality power constraints via matrix-weighted sum mean square
error minimization. The resulting iterative algorithms converge to stationary
points of the corresponding optimization problems. Simulations show that the
proposed algorithms achieve higher end-to-end sum-rates and multiplexing gains
that existing strategies for AF relays, decode-and-forward relays, and direct
transmission. The first algorithm outperforms the other algorithms at high
signal-to-noise ratio (SNR) but performs worse than them at low SNR. Thanks to
power control, the third algorithm outperforms the second algorithm at the cost
of overhead.Comment: submitted to IEEE Transactions on Signal Processing in December 2011,
revised in April 2012 and in September 201
An Experimental Evaluation of Rate Adaptation for Multi-Antenna Systems
AbstractāIncreasingly wireless networks use multi-antenna nodes as in IEEE 802.11n and 802.16. The Physical layer (PHY) in such systems may use the antennas to provide multiple streams of data (spatial multiplexing) or to increase the robustness of fewer streams. These physical layers also provide support for sending packets at different rates by changing the modulation and coding of transmissions. Rate adaptation is the problem of choosing the best transmission mode for the current channel and in these systems requires choosing both the level of spatial multiplexing and the modulation and coding. Hydra is an experimental wireless network node prototype in which both the MAC and PHY are highly programmable. Hydraās PHY is essentially the 802.11n PHY, and currently supports two antennas and the same modulations and codings as 802.11n. Because of limitations of our hardware platform, th
Pneumonia: Drug-Related Problems and Hospital Readmissions
Pneumonia is one of the most common infectious diseases and the fourth leading cause of death globally. According to US statistics in 2019, pneumonia is the most common cause of sepsis and septic shock. In the US, inpatient pneumonia hospitalizations account for the top 10 highest medical costs, totaling $9.5 billion for 960,000 hospital stays. The emergence of antibiotic resistance in the treatment of infectious diseases, including the treatment of pneumonia, is a globally alarming problem. Antibiotic resistance increases the risk of death and re-hospitalization, prolongs hospital stays, and increases treatment costs, and is one of the greatest threats in modern medicine. Drug-related problems (DRPs) in pneumonia - such as suboptimal antibiotic indications, prolonged treatment duration, and drug interactions - increase the rate of antibiotic resistance and adverse effects, thereby leading to an increased burden in treatment. In a context in which novel and effective antibiotics are scarce, mitigating DRPs in order to reduce antibiotic resistance is currently a prime concern. A variety of interventions proven useful in reducing DRPs are antibiotic stewardship programs, the use of biomarkers, computerized physician order entries and clinical decision support systems, and community-acquired pneumonia scores
Vibration and buckling analysis of functionally graded sandwich beams by a new higher-order shear deformation theory
Validation and utilization of an internally controlled multiplex Real-time RT-PCR assay for simultaneous detection of enteroviruses and enterovirus A71 associated with hand foot and mouth disease
AI is a viable alternative to high throughput screening: a 318-target study
: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNetĀ® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNetĀ® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery
Vibration and buckling analysis of functionally graded sandwich beams by a new higher-order shear deformation theory
This paper proposes a new higher-order shear deformation theory for buckling and free vibration analysis of isotropic and functionally graded (FG) sandwich beams. The present theory accounts a new hyperbolic distribution of transverse shear stress and satisfies the traction free boundary conditions. Equations of motion are derived from Lagrangeās equations. Analytical solutions are presented for the isotropic and FG sandwich beams with various boundary conditions. Numerical results for natural frequencies and critical buckling loads obtained using the present theory are compared with those obtained using the higher and first-order shear deformation beam theories. Effects of the boundary conditions, power-law index, span-to-depth ratio and skin-core-skin thickness ratios on the critical buckling loads and natural frequencies of the FG beams are discussed