646 research outputs found

    The volume of liver irradiated during modern free-breathing breast radiotherapy: implications for theory and practice

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    Introduction Incidental liver irradiation during breast radiotherapy can increase the risk of second primary malignancy and induce adverse inflammatory states. This study establishes the volume of liver irradiated during free-breathing breast radiotherapy. Novel associations between liver dose-volume data and systemic interleukin-6 soluble receptor and blood counts are evaluated. Methods The volume of liver within the 10%, 50% and 90% isodose was determined for 100 women with stage 0 to II breast carcinoma undergoing 40Gy in 15 fractions over three weeks tangential irradiation. Blood counts and interleukin 6 soluble receptor concentration were recorded before, during and four weeks after radiotherapy. Dose-volume data for right-sided treatments was associated with longitudinal measures at bivariate and multivariable levels. Results A maximum of 226cm3 (19%), 92 cm3 (8%) and 62 cm3 (5%) of the liver was irradiated within the 10%, 50% and 90% isodose. Liver irradiation was almost exclusively a feature of the 52 right-sided treatments and was strongly correlated with breast volume (ρ = 0.7, p < 0.0001). Liver V10% was significantly associated with interleukin-6 soluble receptor concentration four weeks post-radiotherapy (beta = 0.38, p = 0.01) after controlling for theoretical confounding variables. Conclusion Up to 8% of the liver is irradiated within the primary beam during local right-sided breast radiotherapy. Select use of a deep inspiration breath hold technique would reduce this volume, and minimise the risk of radiation-induced malignancy and acute systemic elevation of inflammatory interleukin 6 soluble receptor

    Evolved orthogonal ribosome purification for in vitro characterization

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    We developed orthogonal ribosome−mRNA pairs in which the orthogonal ribosome (O-ribosome) specifically translates the orthogonal mRNA and the orthogonal mRNA is not a substrate for cellular ribosomes. O-ribosomes have been used to create new cellular circuits to control gene expression in new ways, they have been used to provide new information about the ribosome, and they form a crucial part of foundational technologies for genetic code expansion and encoded and evolvable polymer synthesis in cells. The production of O-ribosomes in the cell makes it challenging to study the properties of O-ribosomes in vitro, because no method exists to purify functional O-ribosomes from cellular ribosomes and other cellular components. Here we present a method for the affinity purification of O-ribosomes, via tagging of the orthogonal 16S ribosomal RNA. We demonstrate that the purified O-ribosomes are pure by primer extension assays, and structurally homogenous by gel electrophoresis and sucrose gradients. We demonstrate the utility of this purification method by providing a preliminary in vitro characterization of Ribo-X, an O-ribosome previously evolved for enhanced unnatural amino acid incorporation in response to amber codons. Our data suggest that the basis of Ribo-X’s in vivo activity is a decreased affinity for RF1

    Quantum Computation by Communication

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    We present a new approach to scalable quantum computing--a ``qubus computer''--which realises qubit measurement and quantum gates through interacting qubits with a quantum communication bus mode. The qubits could be ``static'' matter qubits or ``flying'' optical qubits, but the scheme we focus on here is particularly suited to matter qubits. There is no requirement for direct interaction between the qubits. Universal two-qubit quantum gates may be effected by schemes which involve measurement of the bus mode, or by schemes where the bus disentangles automatically and no measurement is needed. In effect, the approach integrates together qubit degrees of freedom for computation with quantum continuous variables for communication and interaction.Comment: final published versio

    A Study of Cosmic Ray Composition in the Knee Region using Multiple Muon Events in the Soudan 2 Detector

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    Deep underground muon events recorded by the Soudan 2 detector, located at a depth of 2100 meters of water equivalent, have been used to infer the nuclear composition of cosmic rays in the "knee" region of the cosmic ray energy spectrum. The observed muon multiplicity distribution favors a composition model with a substantial proton content in the energy region 800,000 - 13,000,000 GeV/nucleus.Comment: 38 pages including 11 figures, Latex, submitted to Physical Review

    Learning-based Calibration of Flux Crosstalk in Transmon Qubit Arrays

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    Superconducting quantum processors comprising flux-tunable data and coupler qubits are a promising platform for quantum computation. However, magnetic flux crosstalk between the flux-control lines and the constituent qubits impedes precision control of qubit frequencies, presenting a challenge to scaling this platform. In order to implement high-fidelity digital and analog quantum operations, one must characterize the flux crosstalk and compensate for it. In this work, we introduce a learning-based calibration protocol and demonstrate its experimental performance by calibrating an array of 16 flux-tunable transmon qubits. To demonstrate the extensibility of our protocol, we simulate the crosstalk matrix learning procedure for larger arrays of transmon qubits. We observe an empirically linear scaling with system size, while maintaining a median qubit frequency error below 300300 kHz

    Measurement of the Atmospheric Muon Charge Ratio at TeV Energies with MINOS

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    The 5.4 kton MINOS far detector has been taking charge-separated cosmic ray muon data since the beginning of August, 2003 at a depth of 2070 meters-water-equivalent in the Soudan Underground Laboratory, Minnesota, USA. The data with both forward and reversed magnetic field running configurations were combined to minimize systematic errors in the determination of the underground muon charge ratio. When averaged, two independent analyses find the charge ratio underground to be 1.374 +/- 0.004 (stat.) +0.012 -0.010(sys.). Using the map of the Soudan rock overburden, the muon momenta as measured underground were projected to the corresponding values at the surface in the energy range 1-7 TeV. Within this range of energies at the surface, the MINOS data are consistent with the charge ratio being energy independent at the two standard deviation level. When the MINOS results are compared with measurements at lower energies, a clear rise in the charge ratio in the energy range 0.3 -- 1.0 TeV is apparent. A qualitative model shows that the rise is consistent with an increasing contribution of kaon decays to the muon charge ratio.Comment: 16 pages, 17 figure
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