4,473 research outputs found
Timely-Throughput Optimal Scheduling with Prediction
Motivated by the increasing importance of providing delay-guaranteed services
in general computing and communication systems, and the recent wide adoption of
learning and prediction in network control, in this work, we consider a general
stochastic single-server multi-user system and investigate the fundamental
benefit of predictive scheduling in improving timely-throughput, being the rate
of packets that are delivered to destinations before their deadlines. By
adopting an error rate-based prediction model, we first derive a Markov
decision process (MDP) solution to optimize the timely-throughput objective
subject to an average resource consumption constraint. Based on a packet-level
decomposition of the MDP, we explicitly characterize the optimal scheduling
policy and rigorously quantify the timely-throughput improvement due to
predictive-service, which scales as
,
where are constants, is the
true-positive rate in prediction, is the false-negative rate, is the
packet deadline and is the prediction window size. We also conduct
extensive simulations to validate our theoretical findings. Our results provide
novel insights into how prediction and system parameters impact performance and
provide useful guidelines for designing predictive low-latency control
algorithms.Comment: 14 pages, 7 figure
Interleukin-18 enhances vascular calcification and osteogenic differentiation of vascular smooth muscle cells through TRPM7 channel activation
Objective—Vascular calcification (VC) is an important predictor of cardiovascular morbidity and mortality. Osteogenic differentiation of vascular smooth muscle cells (VSMCs) is a key mechanism of VC. Recent studies show that IL-18 (interleukin-18) favors VC while TRPM7 (transient receptor potential melastatin 7) channel upregulation inhibits VC. However, the relationship between IL-18 and TRPM7 is unclear. We questioned whether IL-18 enhances VC and osteogenic differentiation of VSMCs through TRPM7 channel activation.
Approach and Results—Coronary artery calcification and serum IL-18 were measured in patients by computed tomographic scanning and enzyme-linked immunosorbent assay, respectively. Primary rat VSMCs calcification were induced by high inorganic phosphate and exposed to IL-18. VSMCs were also treated with TRPM7 antagonist 2-aminoethoxy-diphenylborate or TRPM7 small interfering RNA to block TRPM7 channel activity and expression. TRPM7 currents were recorded by patch-clamp. Human studies showed that serum IL-18 levels were positively associated with coronary artery calcium scores (r=0.91; P<0.001). In VSMCs, IL-18 significantly decreased expression of contractile markers α-smooth muscle actin, smooth muscle 22 α, and increased calcium deposition, alkaline phosphatase activity, and expression of osteogenic differentiation markers bone morphogenetic protein-2, Runx2, and osteocalcin (P<0.05). IL-18 increased TRPM7 expression through ERK1/2 signaling activation, and TRPM7 currents were augmented by IL-18 treatment. Inhibition of TRPM7 channel by 2-aminoethoxy-diphenylborate or TRPM7 small interfering RNA prevented IL-18–enhanced osteogenic differentiation and VSMCs calcification.
Conclusions—These findings suggest that coronary artery calcification is associated with increased IL-18 levels. IL-18 enhances VSMCs osteogenic differentiation and subsequent VC induced by β-glycerophosphate via TRPM7 channel activation. Accordingly, IL-18 may contribute to VC in proinflammatory conditions
Andreev and Single Particle Tunneling Spectroscopies in Underdoped Cuprates
We study tunneling spectroscopy between a normal metal and underdoped cuprate
superconductor modeled by a phenomenological theory in which the pseudogap is a
precursor to the undoped Mott insulator. In the transparent tunneling limit,
the spectra show a small energy gap associated with Andreev reflection. In the
Giaever limit, the spectra show a large energy gap associated with single
particle tunneling. Our theory semi-quantitatively describes the two gap
behavior observed in tunneling experiments.Comment: 5 pages, 4 figures, submitted to Phys. Rev. Lett. minor changes of
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