4,499 research outputs found
Flexible resource allocation for joint optimization of energy and spectral efficiency in OFDMA multi-cell networks
The radio resource allocation problem is studied, aiming to jointly optimize the energy efficiency (EE) and spectral efficiency (SE) of downlink OFDMA multi-cell networks. Different from existing works on either EE or SE optimization, a novel EE-SE tradeoff (EST) metric, which can capture both the EST relation and the individual cellsâ preferences for EE or SE performance, is introduced as the utility function for each base station (BS). Then the joint EE-SE optimization problem is formulated, and an iterative subchannel allocation and power allocation algorithm is proposed. Numerical results show that the proposed algorithm can exploit the EST relation flexibly and optimize the EE and SE simultaneously to meet diverse EE and SE preferences of individual cells.<br/
Two-copy Quantum Teleportation
We investigate two-copy scenario of quantum teleportation based on Bell
measurements. The detailed protocol is presented and the general expression of
the corresponding optimal teleportation delity is derived, which is given by
the two-copy fully entangled fraction that is invariant under local unitary
transformations. We prove that under a speci c case of the protocol, which is
signi cant for improving the optimal delity, the set of states with their
two-copy fully entangled fractions bounded by a threshold value that required
for useful two-copy teleportation is convex and compact. Hence the witness
operators exist to separate states that are useful for two-copy teleportation
from the rest ones. Moreover, we show that the optimal delity of two-copy
teleportation surpasses that of the original one copy teleportation.Comment: 8 pages, 2 figure
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Systematic Review and Meta-Analysis on the Association Between Outpatient Statins Use and Infectious Disease-Related Mortality
Background: To update and refine systematic literature review on the association between outpatient statins use and mortality in patients with infectious disease. Materials and Methods: We searched articles published before September 31, 2012, on the association between statins and infectious disease-related mortality through electronic databases. Eligible articles were analyzed in Review Manager 5.1. We conducted stratification analysis by study design, infection types, clinical outcomes and study locations. Results: The pooled odds ratio (OR) for death (statins use vs. no use) across the 41 included studies was 0.71 (95% confidence interval: 0.64, 0.78). The corresponding pooled ORs were 0.58 (0.38, 0.90), 0.66 (0.57, 0.75), 0.71 (0.57, 0.89) and 0.83 (0.67, 1.04) for the case-control study, retrospective cohort studies, prospective cohort studies and RCTs; 0.40 (0.20, 0.78), 0.61 (0.41, 0.90), 0.69 (0.62, 0.78) and 0.86 (0.68, 1.09) for bacteremia, sepsis, pneumonia and other infections; 0.62 (0.534, 0.72), 0.68 (0.53, 0.89), 0.71 (0.61, 0.83) and 0.86 (0.70, 1.07) for 30-day, 90-day, in-hospital and long-term (>1 year) mortality, respectively. Conclusions: Outpatient statins use is associated with a lower risk of death in patients with infectious disease in observational studies, but in a less extent in clinical trials. This association also varies considerably by infection types and clinical outcomes
3,4-DihyÂdroxyÂphenethyl acetate
In the title compound, C10H12O4, the dihedral angle between the acetate group and the aromatic ring is 20.47â
(10)°. In the crystal, molÂecules are linked by OâHâŻO hydrogen bonds, forming [001] chains. Weak CâHâŻO interÂactions consolidate the packing
1,2-Bis(4-methylÂphenÂoxy)ethane
In the title compound, C16H18O2, the two aromatic rings are almost orthogonal, making a dihedral angle of 89.41â
(2)°. There is a CâHâŻÏ contact between the methylÂene group and the 4-methylÂphenyl ring. The molecule exhibits twofold symmetry.
A neglected event in endovascular repair of aortic dissection: acute blood pressure variability during aortic angiography
[Purpose]To investigate acute blood pressure change during aortic angiography in aortic dissection endovascular repair, and analyse the potential risk of this incident.[Method]24 patients with aortic dissection underwent endovascular repair in department of vascular surgery of Changhai hospital between May 2016 and July 2016 were enrolled in this research. Patients were divided into two groups: patients underwent general anesthesia and patients underwent lumbar anesthesia. Blood pressure was monitored by intro-artery catheter. Blood pressure readings were recorded every 10 seconds during the procedure of angiography. Outcome of these patients were observed in hospital. [Result] All patients received endovascular aortic repair, with 19 underwent lumbar anesthesia and 5 underwent general anesthesia. Patients underwent lumbar anesthesia presented temporary blood pressure decrease with average of -11.2±13.4mmHg, while patients underwent general anesthesia presented temporary blood pressure elevation with average of 4.2±6.3mmHg. The Maximum time interval were 26.7±12.7s vs25.8±15.8s, and difference in blood pressure between pre- and post-angiography were 1.53±4.4mmHg vs. 4.6±3.4mmHg, both without significance (P>0.05).[Conclusion] Angiography is an effective factor influencing blood pressure during TEVAR, itâs a potential âtriggerâ of intra-operative cardiovascular events. Blood pressure should be kept on proper level to avoid cardiovascular events induced by blood pressure variability with angiography. Angiography with General anesthesia has less influence on blood pressure than with lumbar anesthesia
Poly[[tetraÂaquaÂdi-ÎŒ4-oxalato-ÎŒ2-oxalato-dineoÂdymium(III)] dihydrate]
The title compound, {[Nd2(C2O4)3(H2O)4]·2H2O}n, was synthesized hydroÂthermally in the presence of bisÂ(carbÂoxyÂethylÂgermanium) sesquioxide. It is isostructural with the corresponding Pr compound [Yang et al. (2009). Acta Cryst. E65, m1152âm1153]. The Nd3+ cation is nine-coordinated and its coordination polyhedron can be described as a distorted tricapped trigonal prism. Two Nd3+ ions are connected by two O atoms from two oxalate ions to give a dinuclear Nd2 unit. The unit is further linked to four others via four oxalate ions yielding a layerparallel to (0-11). The linkages between the layers by neighbouring oxalate anions lead to a three-dimensional framework with channels along the c axis. The coordinating and free water molÂecules are located in the channels and make contact with each other and the host framework by weak OâHâŻO hydrogen bonds
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