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Robert D Daniels, Stephen J Bertke, David B Richardson, Elisabeth Cardis, Michael Gillies, Jacqueline A O'Hagan, Richard Haylock, Dominique Laurier, Klervi Leuraud, Monika Moissonnier, Isabelle Thierry-Chef, Ausrele Kesminiene, Mary K Schubauer-Berigan
The paper continues the series of publications from the International Nuclear Workers Study cohort (INWORKS) that comprises 308,297 workers from France, the United Kingdom and the United States, providing 8.2 million person-years of observation from a combined follow-up period (at earliest 1944 to at latest 2005). These workers' external radiation exposures were primarily to photons, resulting in an estimated average career absorbed dose to the colon of 17.4 milligray. The association between cumulative ionizing radiation dose and cancer mortality was evaluated in general relative risk models that describe modification of the excess relative risk (ERR) per gray (Gy) by time since exposure and age at exposure...
December 3, 2016: International Journal of Cancer. Journal International du Cancer
Klaus Reinhardt, Hans Georg Breunig, Karsten König
The decay time of the fluorescence of excited molecules, called fluorescence lifetime, can provide information about the cuticle composition additionally to widely used spectral characteristics. We compared autofluorescence lifetimes of different cuticle regions in the copulatory organ of females of the bedbug, Cimex lectularius. After two-photon excitation at 720 nm, regions recently characterised as being rich in resilin showed a longer bimodal distribution of the mean autofluorescence lifetime τm (tau-m) at 0...
November 29, 2016: Arthropod Structure & Development
Shane Grealish, Malin Parmar
In a recent issue of Nature,Falkner et al. (2016) use chronic two-photon imaging, virus-based transsynaptic tracing, and dynamic calcium indicators to elegantly demonstrate extensive in vivo functional maturation and target-specific functional integration of transplanted embryonic mouse cortical progenitors into adult lesioned visual cortical circuits.
December 1, 2016: Cell Stem Cell
Jesse D Marshall, Jin Zhong Li, Yanping Zhang, Yiyang Gong, François St-Pierre, Michael Z Lin, Mark J Schnitzer
Electrophysiological field potential dynamics are of fundamental interest in basic and clinical neuroscience, but how specific cell types shape these dynamics in the live brain is poorly understood. To empower mechanistic studies, we created an optical technique, TEMPO, that records the aggregate trans-membrane voltage dynamics of genetically specified neurons in freely behaving mice. TEMPO has >10-fold greater sensitivity than prior fiber-optic techniques and attains the noise minimum set by quantum mechanical photon shot noise...
December 1, 2016: Cell
Fani Koukouli, Marie Rooy, Jean-Pierre Changeux, Uwe Maskos
The prefrontal cortex (PFC) plays an important role in cognitive processes, including access to consciousness. The PFC receives significant cholinergic innervation and nicotinic acetylcholine receptors (nAChRs) contribute greatly to the effects of acetylcholine signaling. Using in vivo two-photon imaging of both awake and anesthetized mice, we recorded spontaneous, ongoing neuronal activity in layer II/III in the PFC of WT mice and mice deleted for different nAChR subunits. As in humans, this activity is characterized by synchronous ultraslow fluctuations and neuronal synchronicity is disrupted by light general anesthesia...
December 2, 2016: Proceedings of the National Academy of Sciences of the United States of America
Jared T Broddrick, Benjamin E Rubin, David G Welkie, Niu Du, Nathan Mih, Spencer Diamond, Jenny J Lee, Susan S Golden, Bernhard O Palsson
The model cyanobacterium, Synechococcus elongatus PCC 7942, is a genetically tractable obligate phototroph that is being developed for the bioproduction of high-value chemicals. Genome-scale models (GEMs) have been successfully used to assess and engineer cellular metabolism; however, GEMs of phototrophic metabolism have been limited by the lack of experimental datasets for model validation and the challenges of incorporating photon uptake. Here, we develop a GEM of metabolism in S. elongatus using random barcode transposon site sequencing (RB-TnSeq) essential gene and physiological data specific to photoautotrophic metabolism...
December 1, 2016: Proceedings of the National Academy of Sciences of the United States of America
Inbal Ayzenshtat, Mahesh Miikael Karnani, Jesse Jackson, Rafael Yuste
: Neuronal tuning, defined by the degree of selectivity to a specific stimulus, is a hallmark of cortical computation. Understanding the role of GABAergic interneurons in shaping cortical tuning is now possible with the ability to manipulate interneuron classes selectively. Here, we show that interneurons expressing vasoactive intestinal polypeptide (VIP(+)) regulate the spatial frequency (SF) tuning of pyramidal neurons in mouse visual cortex. Using two-photon calcium imaging and optogenetic manipulations of VIP(+) cell activity, we found that activating VIP(+) cells elicited a stronger network response to stimuli of higher SFs, whereas suppressing VIP(+) cells resulted in a network response shift toward lower SFs...
November 9, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Fabian Ewert, Marcel Bergmann, Peter van Loock
We propose a projection measurement onto encoded Bell states with a static network of linear optical elements. By increasing the size of the quantum error correction code, both Bell measurement efficiency and photon-loss tolerance can be made arbitrarily high at the same time. As a main application, we show that all-optical quantum communication over large distances with communication rates similar to those of classical communication is possible solely based on local state teleportations using optical sources of encoded Bell states, fixed arrays of beam splitters, and photon detectors...
November 18, 2016: Physical Review Letters
Jirawat Tangpanitanon, Victor M Bastidas, Sarah Al-Assam, Pedram Roushan, Dieter Jaksch, Dimitris G Angelakis
We show how to implement topological or Thouless pumping of interacting photons in one-dimensional nonlinear resonator arrays by simply modulating the frequency of the resonators periodically in space and time. The interplay between the interactions and the adiabatic modulations enables robust transport of Fock states with few photons per site. We analyze the transport mechanism via an effective analytic model and study its topological properties and its protection to noise. We conclude by a detailed study of an implementation with existing circuit-QED architectures...
November 18, 2016: Physical Review Letters
Michael Förster, Timo Paschen, Michael Krüger, Christoph Lemell, Georg Wachter, Florian Libisch, Thomas Madlener, Joachim Burgdörfer, Peter Hommelhoff
We demonstrate coherent control of multiphoton and above-threshold photoemission from a single solid-state nanoemitter driven by a fundamental and a weak second harmonic laser pulse. Depending on the relative phase of the two pulses, electron emission is modulated with a contrast of the oscillating current signal of up to 94%. Electron spectra reveal that all observed photon orders are affected simultaneously and similarly. We confirm that photoemission takes place within 10 fs. Accompanying simulations indicate that the current modulation with its large contrast results from two interfering quantum pathways leading to electron emission...
November 18, 2016: Physical Review Letters
Xi-Lin Wang, Luo-Kan Chen, W Li, H-L Huang, C Liu, C Chen, Y-H Luo, Z-E Su, D Wu, Z-D Li, H Lu, Y Hu, X Jiang, C-Z Peng, L Li, N-L Liu, Yu-Ao Chen, Chao-Yang Lu, Jian-Wei Pan
We report the first experimental demonstration of quantum entanglement among ten spatially separated single photons. A near-optimal entangled photon-pair source was developed with simultaneously a source brightness of ∼12  MHz/W, a collection efficiency of ∼70%, and an indistinguishability of ∼91% between independent photons, which was used for a step-by-step engineering of multiphoton entanglement. Under a pump power of 0.57 W, the ten-photon count rate was increased by about 2 orders of magnitude compared to previous experiments, while maintaining a state fidelity sufficiently high for proving the genuine ten-particle entanglement...
November 18, 2016: Physical Review Letters
Mehrdad Mirbabayi, Massimo Porrati
A recent, intriguing Letter by Hawking, Perry, and Strominger suggests that soft photons and gravitons can be regarded as black hole hair and may be relevant to the black hole information paradox. In this Letter we make use of factorization theorems for infrared divergences of the S matrix to argue that by appropriately dressing in and out hard states, the soft-quanta-dependent part of the S matrix becomes essentially trivial. The information paradox can be fully formulated in terms of dressed hard states, which do not depend on soft quanta...
November 18, 2016: Physical Review Letters
A Di Piazza
The only available analytical framework for investigating QED processes in a strong laser field systematically relies on approximating the latter as a plane wave. However, realistic high-intensity laser beams feature much more complex space-time structures than plane waves. Here, we show the feasibility of an analytical framework for investigating strong-field QED processes in laser beams of arbitrary space-time structure by determining the energy spectrum of positrons produced via nonlinear Breit-Wheeler pair production as a function of the background field in the realistic assumption that the energy of the incoming photon is the largest dynamical energy in the problem...
November 18, 2016: Physical Review Letters
L Rigovacca, C Di Franco, B J Metcalf, I A Walmsley, M S Kim
Interference lies at the heart of the behavior of classical and quantum light. It is thus crucial to understand the boundaries between which interference patterns can be explained by a classical electromagnetic description of light and which, on the other hand, can only be understood with a proper quantum mechanical approach. While the case of two-mode interference has received a lot of attention, the multimode case has not yet been fully explored. Here we study a general scenario of intensity interferometry: we derive a bound on the average correlations between pairs of output intensities for the classical wavelike model of light, and we show how it can be violated in a quantum framework...
November 18, 2016: Physical Review Letters
R P M J W Notermans, R J Rengelink, W Vassen
We observe a dramatic difference in optical line shapes of a ^{4}He Bose-Einstein condensate and a ^{3}He degenerate Fermi gas by measuring the 1557-nm 2 ^{3}S-2 ^{1}S magnetic dipole transition (8 Hz natural linewidth) in an optical dipole trap. The 15 kHz FWHM condensate line shape is only broadened by mean field interactions, whereas the degenerate Fermi gas line shape is broadened to 75 kHz FWHM due to the effect of Pauli exclusion on the spatial and momentum distributions. The asymmetric optical line shapes are observed in excellent agreement with line shape models for the quantum degenerate gases...
November 18, 2016: Physical Review Letters
Petra Mozes, Jan Oliver Dittmar, Daniel Habermehl, Eric Tonndorf-Martini, Katalin Hideghety, Anne Dittmar, Jürgen Debus, Stephanie E Combs
BACKGROUND: Meningiomas are usually slow growing, well circumscribed intracranial tumors. In symptom-free cases observation with close follow-up imaging could be performed. Symptomatic meningiomas could be surgically removed and/or treated with radiotherapy. The study aimed to evaluate the volumetric response of intracranial meningiomas at different time points after photon, proton, and a mixed photon and carbon ion boost irradiation. PATIENTS AND METHODS: In Group A 38 patients received proton therapy (median dose: 56 GyE in 1...
December 2, 2016: Acta Oncologica
Guanhai Li, Brendan P Clarke, Jin-Kyu So, Kevin F MacDonald, Nikolay I Zheludev
Recent advances in the physics and technology of light generation via free-electron proximity and impact interactions with nanostructures (gratings, photonic crystals, nano-undulators, metamaterials and antenna arrays) have enabled the development of nanoscale-resolution techniques for such applications as mapping plasmons, studying nanoparticle structural transformations and characterizing luminescent materials (including time-resolved measurements). Here, we introduce a universal approach allowing generation of light with prescribed wavelength, direction, divergence and topological charge via point-excitation of holographic plasmonic metasurfaces...
December 2, 2016: Nature Communications
B Koger, C Kirkby
As a recent area of development in radiation therapy, gold nanoparticle (GNP) enhanced radiation therapy has shown potential to increase tumour dose while maintaining acceptable levels of healthy tissue toxicity. In this study, the effect of varying photon beam energy in GNP enhanced arc radiation therapy (GEART) is quantified through the introduction of a dose scoring metric, and GEART is compared to a conventional radiotherapy treatment. The PENELOPE Monte Carlo code was used to model several simple phantoms consisting of a spherical tumour containing GNPs (concentration: 15 mg Au g(-1) tumour, 0...
December 2, 2016: Physics in Medicine and Biology
Isabela Soares Lopes Branco, Paula Cristina Guimarães Antunes, Gabriel Paiva Fonseca, Hélio Yoriyaz
Model-based dose calculation algorithms (MBDCAs) are the current tools to estimate dose in brachytherapy, which takes into account heterogeneous medium, therefore, departing from water-based formalism (TG-43). One aspect associated to MBCDA is the choice of dose specification medium since it offers two possibilities to report dose: (a) dose to medium in medium, D m,m; and (b) dose to water in medium, D w,m. The discussion about the preferable quantity to be reported is underway. The dose conversion factors, DCF, between dose to water in medium, D w,m, and dose to medium in medium, D m,m, is based on cavity theory and can be obtained using different approaches...
December 21, 2016: Physics in Medicine and Biology
Lars J Petersen, Yuliya Shuytsky, Helle D Zacho
INTRODUCTION: The objective was to describe regional variations in M-staging in patients with newly diagnosed prostate cancer within a Danish county and to compare clinical practice with guideline recommendations. METHODS: Data were as captured from 1) a prospective, non-interventional study counting 635 consecutive patients referred for M-staging in the 2008-2009 period at three regional hospitals within one county, and 2) a questionnaire on M-staging practice completed by the five sites performing M-staging in the same county in 2015...
December 2016: Danish Medical Journal
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