161 research outputs found
Hamiltonian Switching Control of Noisy Bipartite Qubit Systems
We develop a Hamiltonian switching ansatz for bipartite control that is
inspired by the Quantum Approximate Optimization Algorithm (QAOA), to mitigate
environmental noise on qubits. We illustrate the approach with application to
the protection of quantum gates performed on i) a central spin qubit coupling
to bath spins through isotropic Heisenberg interactions, ii) superconducting
transmon qubits coupling to environmental two-level-systems (TLS) through
dipole-dipole interactions, and iii) qubits coupled to both TLS and a Lindblad
bath. The control field is classical and acts only on the system qubits. We use
reinforcement learning with policy gradient (PG) to optimize the Hamiltonian
switching control protocols, using a fidelity objective defined with respect to
specific target quantum gates. We use this approach to demonstrate effective
suppression of both coherent and dissipative noise, with numerical studies
achieving target gate implementations with fidelities over 0.9999 (four nines)
in the majority of our test cases and showing improvement beyond this to values
of 0.999999999 (nine nines) upon a subsequent optimization by Gradient Ascent
Pulse Engineering (GRAPE). We analyze how the control depth, total evolution
time, number of environmental TLS, and choice of optimization method affect the
fidelity achieved by the optimal protocols and reveal some critical behaviors
of bipartite control of quantum gates.Comment: 22 pages, 9 figures, 4 tables. Appendices: 7 pages, 2 figures, 1
tabl
Concrete with triphasic conductive materials for self-monitoring of cracking development subjected to flexure
In this study, the macro steel fiber (SF), carbon fiber (CF) and nano carbon black (NCB) as triphasic
conductive materials were added into concrete, in order to improve the conductivity and ductility of
concrete. The influence of NCB, SF and CF on the post crack behavior and conductivity of concrete was
explored. The effect of the triphasic conductive materials on the self-diagnosing ability to the
loadâdeflection property and crack widening of conductive concrete member subjected to bending were
investigated. The relationship between the fractional change in surface impedance (FCR) and the crack
opening displacement (COD) of concrete beams with conductive materials has been established. The
results illustrated that there is a linear relationship between COD and FCR.National Natural Science Foundation of ChinaThe authors acknowledge the National Natural Science Foundation of China (Grant:
51578109), the National Natural Science Foundation of China (Grant: 51121005), and
Fundaçãopara a CiĂȘncia e a Tecnologia (SFRH/BPD/22680/2005 ), the FEDER Funds through
âPrograma Operacional Factores de Competitividade - COMPETE" and by Portuguese Funds
through FCT-within the Projects PEst-CMAT/UI0013/2011 and PTDC/MAT/112273/2009
Renal Glycosuria as a Novel Early Sign of Colistin-Induced Kidney Damage in Mice
The polymyxin colistin represents a last-resort antibiotic for multidrug-resistant infections, but its use is limited by the frequent onset of acute drug-induced kidney injury (DIKI). It is essential to closely monitor kidney function prior to and during colistin treatment in order to pinpoint early signs of injury and minimize long-term renal dysfunction. To facilitate this, a mouse model of colistin-induced nephrotoxicity was used to uncover novel early markers of colistin-induced DIKI. Increased urinary levels of kidney injury molecule-1 (Kim-1) as well as glycosuria were observed in colistin-treated mice, where alterations of established clinical markers of acute kidney injury (serum creatinine and albuminuria) and emerging markers such as cystatin C were inaccurate in flagging renal damage as confirmed by histology. A direct interaction of colistin with renal glucose reabsorption was ruled out by a cis-inhibition assay in mouse brush border membrane vesicles (BBMV). Immunohistochemical examination and protein quantification by Western blotting showed a marked reduction in the protein amount of sodium-glucose transporter 2 (Sglt2), the main kidney glucose transporter, in renal tissue from colistin-treated mice in comparison to that in control animals. Consistently, BBMV isolated from treated mouse kidneys also showed a reduction in ex vivo glucose uptake compared to that in BBMV isolated from control kidneys. These findings support pathology observations of colistin-induced proximal tubule damage at the site of the brush border membrane, where Sglt2 is expressed, and open avenues for the study of glycosuria as a sensitive, specific, and accessible marker of DIKI during colistin therapy
Retrieval of Ice-Over-Water Cloud Microphysical and Optical Properties Using Passive Radiometers
Current satellite cloud products from passive radiometers provide effective singleâlayer cloud properties by assuming a homogeneous cloud in a pixel, resulting in inevitable biases when multipleâlayer clouds are present in a vertical column. We devise a novel method to retrieve cloud vertical properties for iceâoverâwater clouds using passive radiometers. Based on the absorptivity differences of liquid water and ice clouds at four shortwaveâinfrared channels (centered at 0.87, 1.61, 2.13, and 2.25 ÎŒm), cloud optical thicknesses (COT) and effective radii of both upperâlayer ice and lowerâlayer liquid water clouds are inferred simultaneously. The algorithm works most effectively for clouds with ice COT 5. The simulated spectral reflectances based on our retrieved iceâoverâwater clouds become more consistent with observations than those with a singleâlayer assumption. This new algorithm will improve our understanding of clouds, and we suggest that these four cloud channels should be all included in future satellite sensors
Retrieval of Ice-Over-Water Cloud Microphysical and Optical Properties Using Passive Radiometers
Current satellite cloud products from passive radiometers provide effective singleâlayer cloud properties by assuming a homogeneous cloud in a pixel, resulting in inevitable biases when multipleâlayer clouds are present in a vertical column. We devise a novel method to retrieve cloud vertical properties for iceâoverâwater clouds using passive radiometers. Based on the absorptivity differences of liquid water and ice clouds at four shortwaveâinfrared channels (centered at 0.87, 1.61, 2.13, and 2.25 ÎŒm), cloud optical thicknesses (COT) and effective radii of both upperâlayer ice and lowerâlayer liquid water clouds are inferred simultaneously. The algorithm works most effectively for clouds with ice COT 5. The simulated spectral reflectances based on our retrieved iceâoverâwater clouds become more consistent with observations than those with a singleâlayer assumption. This new algorithm will improve our understanding of clouds, and we suggest that these four cloud channels should be all included in future satellite sensors
Plasma Sphingoid Base Profiles of Patients Diagnosed with Intrinsic or Idiosyncratic Drug-induced Liver Injury
Sphingolipids are exceptionally diverse, comprising hundreds of unique species. The bulk of circulating sphingolipids are synthesized in the liver, thereby plasma sphingolipid profiles represent reliable surrogates of hepatic sphingolipid metabolism and content. As changes in plasma sphingolipid content have been associated to exposure to drugs inducing hepatotoxicity both in vitro and in rodents, in the present study the translatability of the preclinical data was assessed by analyzing the plasma of patients with suspected drug-induced liver injury (DILI) and control subjects. DILI patients, whether intrinsic or idiosyncratic cases, had no alterations in total sphingoid base levels and profile composition compared to controls, whereby cardiovascular disease (CVD) was a confounding factor. Upon exclusion of CVD individuals, elevation of 1-deoxysphingosine (1-deoxySO) in the DILI group emerged. Notably, 1-deoxySO values did not correlate with ALT values. While 1-deoxySO was elevated in all DILI cases, only intrinsic DILI cases concomitantly displayed reduction of select shorter chain sphingoid bases. Significant perturbation of the sphingolipid metabolism observed in this small exploratory clinical study is discussed and put into context, in the consideration that sphingolipids might contribute to the onset and progression of DILI, and that circulating sphingoid bases may function as mechanistic markers to study DILI pathophysiology
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