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https://www.readbyqxmd.com/read/28107554/inclusion-of-a-variable-rbe-into-proton-and-photon-plan-comparison-for-various-fractionation-schedules-in-prostate-radiation-therapy
#1
Jakob Ödén, Kjell Eriksson, Iuliana Toma-Dasu
PURPOSE: A constant relative biological effectiveness (RBE) of 1.1 is currently used in proton radiation therapy to account for the increased biological effectiveness compared to photon therapy. However, there is increasing evidence that proton RBE vary with the linear energy transfer (LET), the dose per fraction and the type of the tissue. Therefore, this study aims to evaluate the impact of disregarding variations in RBE when comparing proton and photon dose plans for prostate treatments for various fractionation schedules using published RBE models and several α/β assumptions...
January 20, 2017: Medical Physics
https://www.readbyqxmd.com/read/28107381/in-vivo-two-photon-imaging-of-astrocytes-in-gfap-gfp-transgenic-mice
#2
Dongjun Guo, Jia Zou, Nicholas Rensing, Michael Wong
Astrocytes play important roles in normal brain function and neurological diseases. In vivo two-photon excitation laser scanning microscopy has the potential to reveal rapid, dynamic structural changes in cells in a variety of physiological and pathological conditions. The type of in vivo imaging method has been shown to affect the plasticity of dendritic spines of neurons, but the optimal in vivo imaging methods of astrocytes have not been established. We compared open-skull and thinned-skull imaging methods for two-photon laser microscopy of live astrocytes in neocortex of GFAP-GFP transgenic mice...
2017: PloS One
https://www.readbyqxmd.com/read/28106460/fermi-large-area-telescope-as-a-galactic-supernovae-axionscope
#3
M Meyer, M Giannotti, A Mirizzi, J Conrad, M A Sánchez-Conde
In a Galactic core-collapse supernova (SN), axionlike particles (ALPs) could be emitted via the Primakoff process and eventually convert into γ rays in the magnetic field of the Milky Way. From a data-driven sensitivity estimate, we find that, for a SN exploding in our Galaxy, the Fermi Large Area Telescope (LAT) would be able to explore the photon-ALP coupling down to g_{aγ}≃2×10^{-13}  GeV^{-1} for an ALP mass m_{a}≲10^{-9}  eV. These values are out of reach of next generation laboratory experiments...
January 6, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28106459/synthetic-dimensions-with-magnetic-fields-and-local-interactions-in-photonic-lattices
#4
Tomoki Ozawa, Iacopo Carusotto
We discuss how one can realize a photonic device that combines synthetic dimensions and synthetic magnetic fields with spatially local interactions. Using an array of ring cavities, the angular coordinate around each cavity spans the synthetic dimension. The synthetic magnetic field arises as the intercavity photon hopping is associated with a change of angular momentum. Photon-photon interactions are local in the periodic angular coordinate around each cavity. Experimentally observable consequences of the synthetic magnetic field and of the local interactions are pointed out...
January 6, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28106454/search-for-invisible-decays-of-sub-gev-dark-photons-in-missing-energy-events-at-the-cern-sps
#5
D Banerjee, V Burtsev, D Cooke, P Crivelli, E Depero, A V Dermenev, S V Donskov, F Dubinin, R R Dusaev, S Emmenegger, A Fabich, V N Frolov, A Gardikiotis, S N Gninenko, M Hösgen, V A Kachanov, A E Karneyeu, B Ketzer, D V Kirpichnikov, M M Kirsanov, S G Kovalenko, V A Kramarenko, L V Kravchuk, N V Krasnikov, S V Kuleshov, V E Lyubovitskij, V Lysan, V A Matveev, Yu V Mikhailov, V V Myalkovskiy, V D Peshekhonov, D V Peshekhonov, O Petuhov, V A Polyakov, B Radics, A Rubbia, V D Samoylenko, V O Tikhomirov, D A Tlisov, A N Toropin, A Yu Trifonov, B Vasilishin, G Vasquez Arenas, P Ulloa, K Zhukov, K Zioutas
We report on a direct search for sub-GeV dark photons (A^{'}), which might be produced in the reaction e^{-}Z→e^{-}ZA^{'} via kinetic mixing with photons by 100 GeV electrons incident on an active target in the NA64 experiment at the CERN SPS. The dark photons would decay invisibly into dark matter particles resulting in events with large missing energy. No evidence for such decays was found with 2.75×10^{9} electrons on target. We set new limits on the γ-A^{'} mixing strength and exclude the invisible A^{'} with a mass ≲100  MeV as an explanation of the muon g_{μ}-2 anomaly...
January 6, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28106452/refractive-index-seen-by-a-probe-beam-interacting-with-a-laser-plasma-system
#6
D Turnbull, C Goyon, G E Kemp, B B Pollock, D Mariscal, L Divol, J S Ross, S Patankar, J D Moody, P Michel
We report the first complete set of measurements of a laser-plasma optical system's refractive index, as seen by a second probe laser beam, as a function of the relative wavelength shift between the two laser beams. Both the imaginary and real refractive index components are found to be in good agreement with linear theory using plasma parameters measured by optical Thomson scattering and interferometry; the former is in contrast to previous work and has implications for crossed-beam energy transfer in indirect-drive inertial confinement fusion, and the latter is measured for the first time...
January 6, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28106422/circular-dichroism-in-multiphoton-ionization-of-resonantly-excited-he-ions
#7
M Ilchen, N Douguet, T Mazza, A J Rafipoor, C Callegari, P Finetti, O Plekan, K C Prince, A Demidovich, C Grazioli, L Avaldi, P Bolognesi, M Coreno, M Di Fraia, M Devetta, Y Ovcharenko, S Düsterer, K Ueda, K Bartschat, A N Grum-Grzhimailo, A V Bozhevolnov, A K Kazansky, N M Kabachnik, M Meyer
Intense, circularly polarized extreme-ultraviolet and near-infrared (NIR) laser pulses are combined to double ionize atomic helium via the oriented intermediate He^{+}(3p) resonance state. Applying angle-resolved electron spectroscopy, we find a large photon helicity dependence of the spectrum and the angular distribution of the electrons ejected from the resonance by NIR multiphoton absorption. The measured circular dichroism is unexpectedly found to vary strongly as a function of the NIR intensity. The experimental data are well described by theoretical modeling and possible mechanisms are discussed...
January 6, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28106175/a-bioorthogonal-turn-on-fluorescent-probe-for-tracking-mitochondrial-nitroxyl-formation
#8
Kyoung Sunwoo, Kondapa Naidu Bobba, Ja-Yun Lim, Taegun Park, Arup Podder, June Seok Heo, Seung Gwan Lee, Sankarprasad Bhuniya, Jong Seung Kim
A bioreductant-resistant 'turn-on' chemodosimetric fluorescent probe Mito-1 has been developed for the detection of mitochondrial HNO in live cells. Mito-1 enables the detection of HNO as low as ∼18 nM. It has the capability to detect both exogenous and endogenous mitochondrial HNO formations in cellular milieus by providing fluorescence images. Its two-photon imaging ability fosters its use as a noninvasive imaging tool for the detection of mitochondrial nitroxyl.
January 20, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28106164/diverse-strategies-of-o2-usage-for-preventing-photo-oxidative-damage-under-co2-limitation-during-algal-photosynthesis
#9
Ginga Shimakawa, Yusuke Matsuda, Kensuke Nakajima, Masahiro Tamoi, Shigeru Shigeoka, Chikahiro Miyake
Photosynthesis produces chemical energy from photon energy in the photosynthetic electron transport and assimilates CO2 using the chemical energy. Thus, CO2 limitation causes an accumulation of excess energy, resulting in reactive oxygen species (ROS) which can cause oxidative damage to cells. O2 can be used as an alternative energy sink when oxygenic phototrophs are exposed to high light. Here, we examined the responses to CO2 limitation and O2 dependency of two secondary algae, Euglena gracilis and Phaeodactylum tricornutum...
January 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28106036/quantum-interference-between-transverse-spatial-waveguide-modes
#10
Aseema Mohanty, Mian Zhang, Avik Dutt, Sven Ramelow, Paulo Nussenzveig, Michal Lipson
Integrated quantum optics has the potential to markedly reduce the footprint and resource requirements of quantum information processing systems, but its practical implementation demands broader utilization of the available degrees of freedom within the optical field. To date, integrated photonic quantum systems have primarily relied on path encoding. However, in the classical regime, the transverse spatial modes of a multi-mode waveguide have been easily manipulated using the waveguide geometry to densely encode information...
January 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/28105830/improving-performance-metrics-of-ultraviolet-photodissociation-mass-spectrometry-by-selective-precursor-ejection
#11
Dustin D Holden, Jennifer S Brodbelt
Confident protein identifications derived from high-throughput bottom-up and top-down proteomics workflows depend on acquisition of thousands of tandem mass spectrometry (MS/MS) spectra with adequate signal-to-noise and accurate mass assignments of the fragment ions. Ultraviolet photodissociation (UVPD) using 193 nm photons has proven to be well-suited for activation and fragmentation of peptides and proteins in ion trap mass spectrometers, but the spectral signal-to-noise ratio (S/N) is typically lower than that obtained from collisional activation methods...
January 3, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28105807/laboratory-setup-for-scanning-free-grazing-emission-x-ray-fluorescence
#12
J Baumann, C Herzog, M Spanier, D Grötzsch, L Lühl, K Witte, A Jonas, S Günther, F Förste, R Hartmann, M Huth, D Kalok, D Steigenhöfer, M Krämer, T Holz, R Dietsch, L Strüder, B Kanngießer, I Mantouvalou
Grazing incidence and grazing emission X-ray fluorescence spectroscopy (GI/GE-XRF) are techniques that enable nondestructive, quantitative analysis of elemental depth profiles with a resolution in the nanometer regime. A laboratory setup for soft X-ray GEXRF measurements is presented. Reasonable measurement times could be achieved by combining a highly brilliant laser produced plasma (LPP) source with a scanning-free GEXRF setup, providing a large solid angle of detection. The detector, a pnCCD, was operated in a single photon counting mode in order to utilize its energy dispersive properties...
January 10, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28105741/potential-use-of-cubic-phase-masks-for-extending-the-range-of-clear-vision-in-presbyopes-initial-calculation-and-simulation-studies
#13
Justo Arines, Citlalli Almaguer, Eva Acosta
PURPOSE: In this paper we analyse the potential use of a non-symmetrical optical element, a cubic phase mask, for extending the range of clear vision of presbyopic eyes. Additionally, we will discuss the appropriateness of the visual Strehl ratio to analyse this sort of presbyopic solution based on non-symmetrical phase masks contrasted with through-focus retinal images. METHODS: In order to evaluate the performance of the cubic phase mask we employed computational Fourier Optics to compute the different visual Strehl criteria as well as simulate the retinal images...
January 20, 2017: Ophthalmic & Physiological Optics: the Journal of the British College of Ophthalmic Opticians (Optometrists)
https://www.readbyqxmd.com/read/28105095/preliminary-results-of-a-non-invasive-method-to-measure-tumor-size-and-distribution-in-vivo
#14
Shu-Ling Fu, Chien-An Chen, Ling-Chien Hung, Moon-Sing Lee, Wen-Yen Chiou, Hon-Yi Lin, Yu-Chieh Su, Ching-Chih Lee, Shih-Kai Hung
Molecular imaging of reporter gene expression in cancer cells can provide rapid, sensitive and non-invasive monitoring of tumor behavior. The aim of the present study was to establish a non-invasive method to measure tumor size and distribution in vivo. Briefly, H-Ras-transformed cells were stably transfected with a plasmid containing the luciferase gene (Luc), designated as Ras/Luc. Ras/Luc cells were injected into the back or tail vein of nude BALB/cAnN-Foxn1nu/CrlNarl mice (age, 6-8 weeks). Mice were subsequently administered D-luciferin via intra-peritoneal injection, prior to image acquisition...
December 2016: Experimental and Therapeutic Medicine
https://www.readbyqxmd.com/read/28104744/spect-ct-imaging-of-the-novel-her2-targeted-peptide-probe-99mtc-hynic-h6f-in-breast-cancer-mouse-models
#15
Liqiang Li, Yue Wu, Zihua Wang, Bing Jia, Zhiyuan Hu, Chengyan Dong, Fan Wang
OBJECTIVES: Overexpression of human epidermal growth factor receptor 2 (HER2) plays important roles in tumorigenesis and tumor progression in breast cancer. Nuclear imaging of HER2 expression in tumors might detect all HER2-positive tumors throughout the body and guide HER2-targeted therapies for patients. We therefore aimed to develop a HER2-targeted peptide probe for breast cancer imaging. A novel single-photon emission computed tomography (SPECT) imaging probe, (99m)Tc-HYNIC-H6F, was prepared and then evaluated in breast cancer animal models...
January 19, 2017: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
https://www.readbyqxmd.com/read/28103749/clinical-practice-with-anti-dementia-drugs-a-revised-third-consensus-statement-from-the-british-association-for-psychopharmacology
#16
John T O'Brien, Clive Holmes, Matthew Jones, Roy Jones, Gill Livingston, Ian McKeith, Peter Mittler, Peter Passmore, Craig Ritchie, Louise Robinson, Elizabeth L Sampson, John-Paul Taylor, Alan Thomas, Alistair Burns
The British Association for Psychopharmacology coordinated a meeting of experts to review and revise its previous 2011 guidelines for clinical practice with anti-dementia drugs. As before, levels of evidence were rated using accepted standards which were then translated into grades of recommendation A-D, with A having the strongest evidence base (from randomised controlled trials) and D the weakest (case studies or expert opinion). Current clinical diagnostic criteria for dementia have sufficient accuracy to be applied in clinical practice (B) and both structural (computed tomography and magnetic resonance imaging) and functional (positron emission tomography and single photon emission computerised tomography) brain imaging can improve diagnostic accuracy in particular situations (B)...
December 1, 2016: Journal of Psychopharmacology
https://www.readbyqxmd.com/read/28102947/a-feasibility-study-of-an-integrated-nir-gamma-visible-imaging-system-for-endoscopic-sentinel-lymph-node-mapping
#17
Han Gyu Kang, Ho-Young Lee, Kyeong Min Kim, Seong-Hyun Song, Gun Chul Hong, Seong Jong Hong
PURPOSE: The aim of this study is to integrate NIR, gamma, and visible imaging tools into a single endoscopic system to overcome the limitation of NIR using gamma imaging and to demonstrate the feasibility of endoscopic NIR/gamma/visible fusion imaging for sentinel lymph node (SLN) mapping with a small animal. METHODS: The endoscopic NIR/gamma/visible imaging system consists of a tungsten pinhole collimator, a plastic focusing lens, a BGO crystal (11 × 11 × 2 mm(3) ), a fiber-optic taper (front = 11 × 11 mm(2) , end = 4 × 4 mm(2) ), a 122-cm long endoscopic fiber bundle, an NIR emission filter, a relay lens, and a CCD camera...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102946/a-portal-dosimetry-dose-prediction-method-based-on-collapsed-cone-algorithm-using-the-clinical-beam-model
#18
J Martínez Ortega, N Gómez González, P Castro Tejero, M Pinto Monedero, N B Tolani, L Núñez Martín, R Sánchez Montero
PURPOSE: Amorphous silicon electronical portal imaging devices (EPIDs) are widely used for dosimetric measurements in Radiation Therapy. The purpose of this work was to determine if a portal dose prediction method can be utilized for dose map calculations based on the linear accelerator model within a commercial treatment planning system (Pinnacle(3) v8.0 m). METHODS: The method was developed for a 6 MV photon beam on the Varian Clinac 21-EX, at a nominal dose rate of 400 MU/min...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102832/silk-protein-as-a-new-optically-transparent-adhesion-layer-for-an-ultra-smooth-sub-10-nm-gold-layer
#19
Kyungtaek Min, Muhammad Umar, Shinyoung Ryu, Soonil Lee, Sunghwan Kim
Ultra-thin and ultra-smooth gold (Au) films are appealing for photonic applications including surface plasmon resonances and transparent contacts. However, poor adhesion at the Au���dielectric interface prohibits the formation of a mechanically stable, ultra-thin, and ultra-smooth Au film. A conventional solution is to use a metallic adhesion layer, such as titanium and chromium however, such layers cause the optical properties of pure Au to deteriorate. Here we report the use of silk protein to enhance the adhesion at the Au���dielectric interfaces, thus obtaining ultra-smooth sub-10 nm Au films...
January 19, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28102829/absorbed-dose-evaluation-of-auger-electron-emitting-radionuclides-impact-of-input-decay-spectra-on-dose-point-kernels-and-s-values
#20
Nadia Falzone, Boon Lee, José Fernández-Varea, Christiana Kartsonaki, Andrew Stuchbery, Tibor Kibedi, Katherine Vallis
AIM: The aim of this study was to investigate the impact of decay data provided by the newly developed stochastic atomic relaxation model <i>BrIccEmis</i> on dose point kernels (DPKs- radial dose distribution around a unit point source) and <i>S</i>-values (absorbed dose per unit cumulated activity) of 14 Auger electron (AE) emitting radionuclides, namely <sup>67</sup>Ga, <sup>80m</sup>Br, <sup>89</sup>Zr, <sup>90</sup>Nb, <sup>99m</sup>Tc, <sup>111</sup>In, <sup>117m</sup>Sn, <sup>119</sup>Sb, <sup>123</sup>I, <sup>124</sup>I, <sup>125</sup>I, <sup>135</sup>La, <sup>195m</sup>Pt and <sup>201</sup>Tl...
January 19, 2017: Physics in Medicine and Biology
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