11,896 research outputs found

    Operator-sum representation of time-dependent density operators and its applications

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    We show that any arbitrary time-dependent density operator of an open system can always be described in terms of an operator-sum representation regardless of its initial condition and the path of its evolution in the state space, and we provide a general expression of Kraus operators for arbitrary time-dependent density operator of an NN-dimensional system. Moreover, applications of our result are illustrated through several examples.Comment: 4 pages, no figure, brief repor

    Practical Decoy State for Quantum Key Distribution

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    Decoy states have recently been proposed as a useful method for substantially improving the performance of quantum key distribution. Here, we present a general theory of the decoy state protocol based on only two decoy states and one signal state. We perform optimization on the choice of intensities of the two decoy states and the signal state. Our result shows that a decoy state protocol with only two types of decoy states--the vacuum and a weak decoy state--asymptotically approaches the theoretical limit of the most general type of decoy state protocols (with an infinite number of decoy states). We also present a one-decoy-state protocol. Moreover, we provide estimations on the effects of statistical fluctuations and suggest that, even for long distance (larger than 100km) QKD, our two-decoy-state protocol can be implemented with only a few hours of experimental data. In conclusion, decoy state quantum key distribution is highly practical.Comment: 31 pages. 6 figures. Preprint forma

    Biochar Additions Alter the Abundance of P-Cycling-Related Bacteria in the Rhizosphere Soil of Portulaca oleracea L. under Salt Stress

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    Numerous reports confirm a positive impact of biochar amendments on soil enzyme activities, nutrient cycles, and, finally, plant growth and development. However, reports explaining the process behind such diverse observations are scarce. The aim of the present study was (1) to evaluate the effect of biochar on the growth of purslane (Portulaca oleracea L.) and nutrients; (2) to determine the response of rhizosphere enzyme activities linked to soil phosphorus cycling after bio-char amendment under non–saline and saline soil conditions. Furthermore, we investigate whether adding biochar to soil alters the abundance of P-cycling-related bacteria. Two rates of biochar (2% and 4%) were applied in pot experiments. Biochar addition of 2% significantly increased plant growth under non-saline and saline soil conditions by 21% and 40%, respectively. Moreover, applying biochar increased soil microbial activity as observed by fluorescein diacetate (FDA) hydrolase activity, as well as phosphomonoesterase activities, and the numbers of colony-forming units (CFU) of P-mobilizing bacteria. Soil amended with 2% biochar concentration increased total soil nitrogen (Nt), phosphorus (P), and total carbon (Ct) concentrations by 18%, 15%, and 90% under non-saline soil conditions and by 29%, 16%, and 90% in saline soil compared the control, respectively. The soil FDA hydrolytic activity and phosphatase strongly correlate with soil Ct, Nt, and P contents. The rhizosphere soil collected after biochar amendment showed a higher abundance of tricalcium phosphate-solubilizing bacteria than the control soil without biochar. Overall, this study demonstrated that 2% maize-derived biochar positively affects halophyte plant growth and thus could be considered for potential use in the reclamation of degraded saline soil.Georg Forster Research FellowshipAlexander von Humboldt Foundatio

    Immunotherapy of lung cancer: An update

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    In Germany lung cancer is the leading cause of cancer-associated death in men. Surgery, chemotherapy and radiation may enhance survival of patients suffering from lung cancer but the enhancement is typically transient and mostly absent with advanced disease; eventually more than 90% of lung cancer patients will die of disease. New approaches to the treatment of lung cancer are urgently needed. Immunotherapy may represent one new approach with low toxicity and high specificity but implementation has been a challenge because of the poor antigenic characterization of these tumors and their ability to escape immune responses. Several different immunotherapeutic treatment strategies have been developed. This review examines the current state of development and recent advances with respect to non-specific immune stimulation, cellular immunotherapy ( specific and non-specific), therapeutic cancer vaccines and gene therapy for lung cancer. The focus is primarily placed on immunotherapeutic cancer treatments that are already in clinical trial or well progressed in preclinical studies. Although there seems to be a promising future for immunotherapy in lung cancer, presently there is not standard immunotherapy available for clinical routine

    Ultrafast spin polarization in a multiferroic manganite BiFe0.5Mn0.5O3 thin film

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    In this work, we present observations of ultrafast carrier dynamics and spin polarization in a multiferroic manganite BiFe0.5Mn0.5O3 film excited by linearly and circularly polarized femtosecond pulses, respectively. The d-band charge transfer transition is reasonably assigned to Γ3 → Γ5. The transient reflectivity decay on a time scale as fast as only 0.3 ps is consistent with the picture of ultrafast electron-phonon coupling. The ultrafast switching of polarization ellipticity (\u3c 150 fs) originates from a transient coherent spin polarization by optical orientation. The ultrafast spin polarization switching is assigned to the Raman coherence process

    Interactive Effects of Biochar, Nitrogen, and Phosphorous on the Symbiotic Performance, Growth, and Nutrient Uptake of Soybean (Glycine max L.)

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    Numerous studies reported the positive effect of soil amendment with biochar on plant development. However, little is known about biochar and its interrelation with nitrogen (N) and phosphorous (P) additions and their impact on plant growth. We carried out greenhouse experiments to understand the interactive effects of nitrogen and phosphorus supply, as well as biochar amendment, on the symbiotic performance of soybean (Glycine max L.) with Bradyrhizobium japonicum, and plant growth and nutrient uptake. The biochar was produced from maize by heating at 600 °C for 30 min and used for pot experiments at an application rate of 2%. Plants were fertilized with two different concentrations of P (KH2PO4) and N (NH4NO3). Biochar application significantly increased the dry weight of soybean root and shoot biomass, by 34% and 42%, under low nitrogen and low phosphorus supply, respectively. Bradyrhizobium japonicum inoculation enhanced the dry weight of shoot biomass significantly, by 41% and 67%, in soil without biochar and with biochar addition, respectively. The nodule number was 19% higher in plants grown under low N combined with low or high P, than in high N combinations, while biochar application increased nodule number in roots. Moreover, biochar application increased N uptake of plants in all soil treatments with N or P supply, compared with B. japonicum-inoculated and uninoculated plants. A statistical difference in P uptake of plants between biochar and nutrient levels was observed with low N and high P supply in the soil. Our results show that the interactions between nitrogen, phosphorus, and biochar affect soybean growth by improving the symbiotic performance of B. japonicum and the growth and nutrition of soybean. We observed strong positive correlations between plant shoot biomass, root biomass, and N and P uptake. These data indicated that the combined use of biochar and low N, P application can be an effective approach in improving soybean growth with minimum nutrient input.Peer Reviewe

    タンノウ テキシュツジュツ デ チュウイ スベキ タンカン ソウコウ イジョウ Cystohepatic duct ノ 1レイ

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     A 74-year-old man presented with epigastralgia and was diagnosed as having cholelithiasis. Endoscopic retrograde cholangiopancreatography (ERCP) initially visualized the cystic duct with the Heister valve from the common bile duct, and then two intra-hepatic biliary ducts of segment 5 (B5) were visualized from the neck of the gallbladder. There was a contrast medium filling defect in B5, which was considered to be due to an incarcerated stone. Magnetic resonance cholangiopancreatography (MRCP) and three-dimensional computed tomography (CT) cholangiography showed similar findings, suggesting that the patient had a biliary anomaly of the cystohepatic duct in which two intrahepatic bile ducts (B5) flowed into the neck of the gallbladder and a stone incarcerated in the neck of the gallbladder. At surgery, during mobilization of the gallbladder, there was a thick string between the liver and the gallbladder, and this was considered to be the junction of B5 with the gallbladder. Therefore, the neck of the gallbladder was cut, and an incarcerated stone 10 mm in diameter was removed. Intraoperative cholangiography revealed that the cystohepatic ducts were preserved. The postoperative course was uneventful and there was no bile leakage or liver dysfunction. Although cystohepatic duct is a rare biliary anomaly, the surgeon should be alert for its possible presence during cholecystectomy. When cholecystectomy is scheduled, more than one preoperative examination by three-dimensional CT cholangiography, MRCP or ERCP should be performed, and the surgeon should be careful not to overlook any biliary anomaly. Keywords: cystohepatic duct, biliary duct anomaly, cholecystectomy, three-dimensional computed tomography, gallston

    Decoy state quantum key distribution with two-way classical post-processing

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    Decoy states have recently been proposed as a useful method for substantially improving the performance of quantum key distribution protocols when a coherent state source is used. Previously, data post-processing schemes based on one-way classical communications were considered for use with decoy states. In this paper, we develop two data post-processing schemes for the decoy-state method using two-way classical communications. Our numerical simulation (using parameters from a specific QKD experiment as an example) results show that our scheme is able to extend the maximal secure distance from 142km (using only one-way classical communications with decoy states) to 181km. The second scheme is able to achieve a 10% greater key generation rate in the whole regime of distances
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