[en] We consider the optimal parameter estimation for a two-level system coupled to multiple bosonic reservoirs. By using quantum Fisher information (QFI), we investigate the effect of the Markovian reservoirs’ number N on QFI in both weak and strong coupling regimes for a two-level system surrounded by N zero-temperature reservoirs of field modes initially in the vacua. The results show that the dynamics of QFI non-monotonically decays to zero with revival oscillations at some time in the weak coupling regime depending on the reservoirs’ parameters. Furthermore, we also present the relations between the QFI flow, the flows of energy and information, and the sign of the decay rate to gain insight into the physical processes characterizing the dynamics. (paper)

[en] In this paper, we address the dynamics of nonclassical correlation, quantified by local quantum uncertainty (LQU) in a two-qubit system subjected to classical environmental noise when the initial states of system are prepared in a specific class of Bell states. Two different configurations of the local noisy environment are examined. In the first case, we consider a system of two independently qubits, each locally interacting with its classical random noise, whereas in the second case we consider only one of qubits subject to a classical random noise. Our results show that the dynamics of LQU is strongly related to both the dephasing and relaxation factors. The behaviors of LQU in above two cases exhibit similar variation, with monotonic decay in the weak coupling region, while revivals in the strong coupling region depending on the ratio of the switching rate and coupling strength to the qubit. By controlling this ratio, long-time survival of LQU is obtained. Therefore, our results may open an interesting perspective in using of the long-time survival of quantum correlations for practical applications in quantum information science. (paper)

[en] We study the effects of the interaction strength and the initial phase on the dynamics of quantum discord in a two-qubit system under both spontaneous emission and dephasing noisy channels. It is shown that the time evolution of quantum discord displays quicker oscillations with increasing inter-qubit interaction strength but the effect of the initial phase closely depends on the interaction between the qubits. Only for non-zero inter-qubit interaction cases, the evolution of quantum discord is affected by the initial phase and its oscillating amplitude increases with increasing initial phase. A comparison between evolutions of quantum discord and entanglement is also made. (paper)

[en] Local quantum uncertainty (LQU) as a reliable measure of nonclassical correlations has been recently proposed by Girolami et al. (Phys Rev Lett 110:240402, 2013). In this paper, we have derived an explicit analytical expression of LQU and presented the level surfaces of constant LQU for a class of two-qubit X-states beyond Bell-diagonal states. The dynamical behavior of quantum correlations via the LQU under decoherence environment is studied, and the phenomenon of a sudden change of LQU is demonstrated. Our results are illustrated through the action of different noisy environments individually on a single qubit of quantum system where there is a necessary condition for the occurrence of sudden change of LQU.

[en] Objective: To compare the performance of T₂-weighted two-shot spin-echo version of echo planar imaging (SE-EPI), respiratory-gating fast spin-echo (FSE) and single -shot fast spin echo (SSFSE) sequences for the evaluation of focal hepatic lesions. Methods: Breath-hold two-shot SE-EPI (TR=5999ms and 1999ms) of the liver was performed in 14 healthy volunteers and 21 patients, and was compared with respiratory -gating T₂-weithted FSE and SSFSE. The fat-suppression technique was used in each sequence.. The signal-to-noise ratio (SNR) of the liver and lesion and the contrast-to-noise ratio (CNR) of the lesion-to-liver were quantitatively analyzed. The image quality and artifacts were also comparatively studied. Results: Quantitatively, SE_EPI, SSFSE and FSE sequences showed non-significant differences (P>0.05) in liver/lesion CNR, SNR of Liver and lesion and the general image quality. Susceptibility artifacts and chemical shift artifacts on SE-EPI were more than SSFSE and FSE. There were fewer motion and ghost artifacts on SE-EPI images compared to FSE images (P<0.05). Conclusion: SE-EPI of the liver can provide better quality T₂-weighted images in shorter acquisition times compared with respiratory-gating FSE and SSFSE. There is no particular requirement for patients to suspend their breath during the aquisition. This technique may be useful in clinical application of hepatic MR imaging. (authors)

[en] Objective: To explore the diagnostic value of MPA with a moving-bed infusion-tracking technique in lower limb arterial disease of diabetic patients. Methods: MPA of low limb artery in 21 diabetes patients were analyzed. And the results were compared with that of DSA. Results: 16 cases were excellent MR imaging and 5 were good. In 10 sections of low limb artery, 29 stenosis were displayed by MPA and 36 by DSA. The total accordance rate was 80.6% There was no statistically significant difference between MRA and DSA in the diagnosis of stenosis. Conclusion: MPA was a reliable method and non-invasive method with excellent correlation between MRA and DSA in the diagnosis of' arterial stenosis. (authors)

[en] Objective: To evaluate the multislice CT-guided percutaneous vertebroplasty (PVP) in treatment of vertebral metastases. Methods: The efficacy and complications of CT-guided PVP in 25 patients with vertebral metastases were retrospectively reviewed. Results: The percutaneous paracentesis was successful in all 30 vertebrae in 25 patients. After PVP, the pain in all patients subsided gradually. Complete remission was obtained in 18 cases out of 25, and partial remission was accomplished in the rest 7 cases in one month after the intervention. In one case, bone cement (polymethy methacrylate PMMA) leaked into vertebral disc during the procedure while the treatment remained asymptomatic eventually. Conclusion: The multislice CT-guided PVP is a simple, precise, and safe interventional procedure, which is a practical treatment to improve the life quality of patients with vertebral metastases. (authors)

[en] Objective: To evaluate the efficacy of intratumoral injection of recombinant adenovirus p53 agent (rAd-p53) combined with ¹²⁵I seed interstitial brachytherapy in the hepatocellular carcinoma residues. Methods: Forty nine hepatocellular carcinoma patients after trans arterial chemo embolization (TACE) and physical ablation therapy were studied. Twenty cases (33 lesions) in combined group were treated by intratumoral injection with rAd-p53 combined with ¹²⁵I seed interstitial brachytherapy. Twenty nine patients (47 lesions) injected with ¹²⁵I seed interstitial brachytherapy were treated as control group. The adverse reactions were observed in 3 day, 1 week and 2 weeks after the therapy. The short period therapeutic effect were observed in 1 month. Results: Three days after the operation, the main adverse reaction included rigor, fever, anergy, myalgia, and arthralgia. The incidence of adverse events was significantly higher in combination group than in control group. There was no significant difference in other adverse reaction including nausea, vomiting and abdominal pain. After one week, 1 case of combined group caught fever with other adverse reactions mitigated. After 2 weeks, all adverse reactions disappeared. All patients showed no severe complications, such as bleeding, biliary fistula, cholecystitis and intestinal fistula. No white blood cell reduction and no hepatic and renal dysfunction. Physical condition (Kamofsky scores) was no significant decrease. Short term effects indicated that effective ratio (CR + PR) of the combination group and control group were 90.9% and 76.6% respectively, but there was no significant difference. Conclusion: Intratumoral injection of rAd-p53 combined with ¹²⁵I seed interstitial brachytherapy is a safety treatment for hepatocellualr carcinoma. (authors)

[en] Objective: To evaluate the value of MR angiography and cholangiopancreatography on the diagnosis of vascular and biliary complications after liver transplantation. Methods: Seven consecutive adult patients underwent 16 MR imaging examinations after orthotopic liver transplantation using a breath-hold 2D TSE and FLASH. MR cholangiopancreatography and triphasic contrast-enhanced 3D imaging (average dose, 0.30 mmol/kg of Gd-DTPA) was performed and imaging findings after liver transplantation was analyzed. Results: Two normal cases showed a small amount of ascites or fluid in the perihepatic region or the intersegmental fissure of the transplanted liver, as well as transient right-sided pleural effusion and mild lymph swelling. Four cases had vascular complication including elongation and kinking of hepatic artery, aneurysm formation of donor's hepatic artery, narrowing of the portal vein at the anastomosis and clubbed dilataltion of hepatic veins. Three cases had biliary complications including anastomotic and nonanastomotic strictures, mucocele and bile leakage. Conclusion: Dynamic enhanced 3D MR angiography imaging combined with MR cholangiopancreatography can provide a comprehensive assessment of vascular and biliary complications in most recipients of liver transplants. MR imaging after liver transplants is significative to guide the diagnosis and treatment. (authors)

[en] It is known that the surface plasmons (SPs) supported by graphene can be strongly coupled with electric SPs supported by the metamaterial and with symmetric and antisymmetric surface phonon polaritons (SPhPs) supported by silicon carbide (SiC). It has been shown that coated SiC thin films can efficiently enhance near-field radiative heat transfer between metamaterials. In this study, we theoretically investigate near-field heat transfer between graphene–SiC–graphene–metamaterial (GSGM) multilayer structures. The heat transfer between GSGM structures is significantly larger than that between SiC-coated metamaterials when the chemical potential of graphene is not very high. Moreover, the structure proposed in this study behaves much better than the previous SiC/graphene/metamaterial in enhancing the near-field radiative heat transfer. The findings in this study provide a basis for active controlling of near-field radiative heat transfer. Graphical abstract:

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