389 research outputs found

    Biochemical status of vitamin A in colorectal cancer

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    Serum vitamin A and its carrier proteins, retinol-binding protein and prealbumin, were measured in 41 colorectal cancer patients, 40 patients with benign colorectal disease, and 31 healthy subjects. Serum samples were obtained from the Mayo Clinic (NCI-Serum diagnostic Bank, Rochester, MN), The values for each of the three parameters were significantly lower in colorectal cancer patients than in healthy subjects but were litte1e different from the val ues seen in patients with benign disease

    Number of iteration analysis for complex fss shape using GA for efficient ESG

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    ESG stand for Energy-Saving Glass is a special shielded glass with a metallic oxide layer to abuse undesirable of infrared and ultraviolet radiation into construction assemblies like our home. Firstly, different number of the iteration is the main thing to study a performance of the frequency selective surface shape using genetic algorithm (GA) for efficient energy saving glass (ESG). Three different values for the number of iterations were taken that is 1500, 2000 1nd 5000. Before that, the response of this complex FSS shape on incident electromagnetic wave with different symmetry shape are investigating. Three of them are no symmetrical shape, ¼ symmetrical shape, and 1/8 symmetrical shape. The 1500 number simulation considered about 89.000 per second, compared with 2000 iteration and 5000 iterations had consumed 105.09 per second and 196.00 per second, respectively. For 1/8 symmetry complex FSS shape, it demonstrations the improved performance of transmission loss at 1.2 GHz with - 40 dB. A 2 dB of transmission loss is achieved at WLAN application of 2.45 GHz with 0°, 30°, and 45° incidence angle shows

    Measurement of gamma p --> K+ Lambda and gamma p --> K+ Sigma0 at photon energies up to 2.6 GeV

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    The reactions gamma p --> K+ Lambda and gamma p --> K+ Sigma0 were measured in the energy range from threshold up to a photon energy of 2.6 GeV. The data were taken with the SAPHIR detector at the electron stretcher facility, ELSA. Results on cross sections and hyperon polarizations are presented as a function of kaon production angle and photon energy. The total cross section for Lambda production rises steeply with energy close to threshold, whereas the Sigma0 cross section rises slowly to a maximum at about E_gamma = 1.45 GeV. Cross sections together with their angular decompositions into Legendre polynomials suggest contributions from resonance production for both reactions. In general, the induced polarization of Lambda has negative values in the kaon forward direction and positive values in the backward direction. The magnitude varies with energy. The polarization of Sigma0 follows a similar angular and energy dependence as that of Lambda, but with opposite sign.Comment: 21 pages, 25 figures, submitted to Eur. Phys. J.

    Evidence for the positive-strangeness pentaquark Θ+\Theta^+ in photoproduction with the SAPHIR detector at ELSA

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    The positive--strangeness baryon resonance Θ+\Theta^+ is observed in photoproduction of the nK+Ks0\rm nK^+K^0_s final state with the SAPHIR detector at the Bonn ELectron Stretcher Accelerator ELSA. It is seen as a peak in the nK+\rm nK^+ invariant mass distribution with a 4.8σ4.8\sigma confidence level. We find a mass MΘ+=1540±4±2\rm M_{\Theta^+} = 1540\pm 4\pm 2 MeV and an upper limit of the width ΓΘ+<25\rm \Gamma_{\Theta^+} < 25 MeV at 90% c.l. From the absence of a signal in the pK+\rm pK^+ invariant mass distribution in γppK+K\rm\gamma p\to pK^+K^- at the expected strength we conclude that the Θ+\Theta^+ must be isoscalar.Comment: 9 pages, 4 figure

    K^0 pi^0 Sigma^+ and K^*0 Sigma^+ photoproduction off the proton

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    The exclusive reactions γpK0Σ+(1189)\gamma p \to K^{*0} \Sigma^+(1189) and γpK0π0Σ+(1189)\gamma p \to K^{0} \pi^{0}\Sigma^+(1189), leading to the p 4π0\pi^{0} final state, have been measured with a tagged photon beam for incident energies from threshold up to 2.5 GeV. The experiment has been performed at the tagged photon facility of the ELSA accelerator (Bonn). The Crystal Barrel and TAPS detectors were combined to a photon detector system of almost 4π\pi geometrical acceptance. Differential and total cross sections are reported. At energies close to the threshold, a flat angular distribution has been observed for the reaction γpK0π0Σ+\gamma p\to K^{0} \pi^{0}\Sigma^+ suggesting dominant s-channel production. Σ(1385)\Sigma^*(1385) and higher lying hyperon states have been observed. An enhancement in the forward direction in the angular distributions of the reaction γpK0Σ+\gamma p \to K^{*0}\Sigma^+ indicates a tt-channel exchange contribution to the reaction mechanism. The experimental data are in reasonable agreement with recent theoretical predictions.Comment: 11 pages, 13 figures, submitted to EPJ

    The {\eta}'-carbon potential at low meson momenta

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    The production of η\eta^\prime mesons in coincidence with forward-going protons has been studied in photon-induced reactions on 12^{12}C and on a liquid hydrogen (LH2_2) target for incoming photon energies of 1.3-2.6 GeV at the electron accelerator ELSA. The η\eta^\prime mesons have been identified via the ηπ0π0η6γ\eta^\prime\rightarrow \pi^0 \pi^0\eta \rightarrow 6 \gamma decay registered with the CBELSA/TAPS detector system. Coincident protons have been identified in the MiniTAPS BaF2_2 array at polar angles of 2θp112^{\circ} \le \theta _{p} \le 11^{\circ}. Under these kinematic constraints the η\eta^\prime mesons are produced with relatively low kinetic energy (\approx 150 MeV) since the coincident protons take over most of the momentum of the incident-photon beam. For the C-target this allows the determination of the real part of the η\eta^\prime-carbon potential at low meson momenta by comparing with collision model calculations of the η\eta^\prime kinetic energy distribution and excitation function. Fitting the latter data for η\eta^\prime mesons going backwards in the center-of-mass system yields a potential depth of V = -(44 ±\pm 16(stat)±\pm15(syst)) MeV, consistent with earlier determinations of the potential depth in inclusive measurements for average η\eta^\prime momenta of \approx 1.1 GeV/cc. Within the experimental uncertainties, there is no indication of a momentum dependence of the η\eta^\prime-carbon potential. The LH2_2 data, taken as a reference to check the data analysis and the model calculations, provide differential and integral cross sections in good agreement with previous results for η\eta^\prime photoproduction off the free proton.Comment: 9 pages, 13 figures. arXiv admin note: text overlap with arXiv:1608.0607

    Photoproduction of eta mesons from the neutron: cross sections and double polarization observable E

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    Photoproduction of η\eta mesons from neutrons} \abstract{Results from measurements of the photoproduction of η\eta mesons from quasifree protons and neutrons are summarized. The experiments were performed with the CBELSA/TAPS detector at the electron accelerator ELSA in Bonn using the η3π06γ\eta\to3\pi^{0}\to6\gamma decay. A liquid deuterium target was used for the measurement of total cross sections and angular distributions. The results confirm earlier measurements from Bonn and the MAMI facility in Mainz about the existence of a narrow structure in the excitation function of γnnη\gamma n\rightarrow n\eta. The current angular distributions show a forward-backward asymmetry, which was previously not seen, but was predicted by model calculations including an additional narrow P11P_{11} state. Furthermore, data obtained with a longitudinally polarized, deuterated butanol target and a circularly polarized photon beam were analyzed to determine the double polarization observable EE. Both data sets together were also used to extract the helicity dependent cross sections σ1/2\sigma_{1/2} and σ3/2\sigma_{3/2}. The narrow structure in the excitation function of γnnη\gamma n\rightarrow n\eta appears associated with the helicity-1/2 component of the reaction

    Experimental constraints on the ω\omega-nucleus real potential

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    In a search for ω\omega mesic states, the production of ω\omega-mesons in coincidence with forward going protons has been studied in photon induced reactions on 12^{12}C for incident photon energies of 1250 - 3100 MeV. The π0γ\pi^0 \gamma pairs from decays of bound or quasi-free ω\omega-mesons have been measured with the CBELSA/TAPS detector system in coincidence with protons registered in the MiniTAPS forward array. Structures in the total energy distribution of the π0γ\pi^0 \gamma pairs, which would indicate the population and decay of bound ω 11\omega~^{11}B states, are not observed. The π0γ\pi^0 \gamma cross section of 0.3 nb/MeV/sr observed in the bound state energy regime between -100 and 0 MeV may be accounted for by yield leaking into the bound state regime because of the large in-medium width of the ω\omega-meson. A comparison of the measured total energy distribution with calculations suggests the real part V0V_0 of the ω 11\omega~^{11}B potential to be small and only weakly attractive with V0(ρ=ρ0)=15±V_0(\rho=\rho_0) = -15\pm 35(stat) ±\pm20(syst) MeV in contrast to some theoretical predictions of attractive potentials with a depth of 100 - 150 MeV.Comment: 13 pages, 8 figure

    First measurement of the helicity asymmetry for γppπ0\gamma p\rightarrow p\pi^0 in the resonance region

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    The first measurement of the helicity dependence of the photoproduction cross section of single neutral pions off protons is reported for photon energies from 600 to 2300\,MeV, covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, and BnGa partial wave analyses. Strikingly large differences between data and predictions are observed which are traced to differences in the helicity amplitudes of well known and established resonances. Precise values for the helicity amplitudes of several resonances are reported
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