4,504 research outputs found

    Dissection of the Candida albicans class I chitin synthase promoters

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    We acknowledge financial support from the Biotechnology and Biological Sciences Research Council (10161), Medical Research Council (New Investigator Award to C.A.M.), the European Community FUNGALWALL and SIGNALPATH initiatives and the Wellcome Trust.Peer reviewedPublisher PD

    Biologic variability of human foreskin fibroblasts in 2D and 3D culture: implications for a wound healing model

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    <p>Abstract</p> <p>Background</p> <p>The fibroblast-populated 3D collagen matrix is a model of tissue and healing which has been used since the 1980's. It was hypothesized that anchorage disruption of the collagen matrix would produce p53-dependent apoptosis in the embedded fibroblasts, but results of hypothesis testing were variant.</p> <p>Findings</p> <p>The response of p53 to anchorage disruption in 3D culture or to UV irradiation in 2D culture was influenced both by fibroblast strain and culture conditions. It also was determined that data scatter in a collagen matrix contraction assay was related to fibroblast strain and possibly to technical factors, such as cell culture technician and/or number of matrices utilized. Subsequent analysis suggested that phenotypic drift and/or inter-strain genetic variability may have been responsible for the data scatter. In addition, several technical factors were identified that may have contributed to the scatter.</p> <p>Conclusion</p> <p>Experimentation with human foreskin fibroblasts in both 2D and 3D culture can produce variant data. The underlying cause of the data scatter appears to be partially due to the biologic variability of the fibroblast.</p

    Faddeev study of heavy baryon spectroscopy

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    We investigate the structure of heavy baryons containing a charm or a bottom quark. We employ a constituent quark model successful in the description of the baryon-baryon interaction which is consistent with the light baryon spectra. We solve exactly the three-quark problem by means of the Faddeev method in momentum space. Heavy baryon spectrum shows a manifest compromise between perturbative and nonperturbative contributions. The flavor dependence of the one-gluon exchange is analyzed. We assign quantum numbers to some already observed resonances and we predict the first radial and orbital excitations of all states with J=1/2J=1/2 or 3/2. We combine our results with heavy quark symmetry and lowest-order SU(3) symmetry breaking to predict the masses and quantum numbers of six still non-measured ground-state beauty baryons.Comment: 22 pages, 4 figures, 8 tables. Accepted for publication in J. Phys.

    Upper limits for a narrow resonance in the reaction p + p -> K^+ + (Lambda p)

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    The reaction pp -> K^+ + (Lambda p) has been measured at T_p = 1.953 GeV and \Theta = 0 deg with a high missing mass resolution in order to study the Lambda p final state interaction. Narrow S = -1 resonances predicted by bag model calculations are not visible in the missing mass spectrum. Small structures observed in a previous experiment are not confirmed. Upper limits for the production cross section of a narrow resonance are deduced for missing masses between 2058 and 2105 MeV/c^2.Comment: 8 pages, 5 figure

    26 Weryfikacja obliczeń dawek wykonywanych za pomocą systemu CadPlan

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    Radioterapia jest procesem złożonym obejmującym szereg krokó proceduralnych. Dokładność każdego z nich wpływa bezpośrednio na wynik leczenia. Niedokładności lub błędy podczas komputerowego planowania leczenia mogą zmniejszyć odsetek wyleczeń lub nawet spowodować poważne komplikacje u napromienianych pacjentów. Zalecenie niezależnego obliczania dawki przynajmniej w jednym punkcie planu, np. w izocentrum lub w punkcie położonym blisko środka guza, nabiera szczególnego znaczenia zwłaszcza w okresie wdrażania do praktyki klinicznej nowego komputerowego systemu do planowania leczenia.CelOpracowanie procedury kontroli jakości obliczeń dawek wykonywanych za pomocą systemuCadPlan.Materiał i metodyJednym z elementów linii terapeutycznej firmy Varian zainstalowanej w Centrum Onkologii w Krakowie jest komputerowy system planowania leczenia CadPlan współpracujący z tomografem komputerowym GE Sytec 3000i i połączony po poprzez system zarządzania i weryfikacji VARiS z akceleratorem liniowym CLlNAC 600C. Pomiary dozymetryczne akceleratora CLlNAC 600C wytwarzającego wiązkę fotonową o energii 6 MV wykonano w zakresie pokrywającym wymagania zarówno systemu CadPlan jak i opracowanych wcześniej w naszym Zakładzie Fizyki Medycznej i uruchomionych na minikomputerze typu IBM PC programów APARAT i PLAN. Program APARAT dla zadanych parametrów wiązek promieniowania fotonowego podaje aktualne wydajności aparatu terapeutycznego i procentowe dawki głębokościowe, a po wprowadzeniu frakcyjnej dawki wlotowej określa czas ekspozycji albo liczbę jednostek monitorowych odpowiednio dla napromieniania na aparacie kobaltowym lub akceleratorze. Program PLAN umożliwia realizację planowania leczenia 2D wiązkami fotonowymi z uwzględnieniem niejednorodności obszaru napromienianego.Wyniki obliczeń systemu CadPlan, zamieszczone na wydrukach, są weryfikowane za pomocą programu APARAT. W przypadku występowania niejednokrotności (np. płuca) poprawność obliczonych dawek sprawdzana jest przy użyciu programu PLAN, do którego dane topometryczne wprowadzone są wprost z wydrukowanego przez CadPlan przekroju poprzecznego pacjenta w płaszczyźnie centralnej wiązki.Wyniki i wnioskiOpracowany sposób kontroli poprawności obliczeń dawek wykonywanych za pomocą systemu CadPlan oparty jest na wieloletnim doświadczeniu w użytkowaniu programów komputerowych APARAT i PLAN. Zastosowana metoda pozwala na stosunkowo szybkie sprawdzenie obliczonych za pomocą systemu CadPlan wartości dawek w wybranych punktach na osiach wiązek. Procedura jest łatwa w użyciu i przejrzysta, a jej rutynowe stosowanie przyczynia się do zapewnienia bezpieczeństwa napromienianych pacjentów

    Cross section of the ppK+Σ+npp\to K^+\Sigma^+n reaction close to threshold

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    We have measured inclusive data on K+K^+-meson production in pppp collisions at COSY J\"ulich close to the hyperon production threshold and determined the hyperon-nucleon invariant mass spectra. The spectra were decomposed into three parts: Λp\Lambda p, Σ0p\Sigma^0p and Σ+n\Sigma^+n. The cross section for the Σ+n\Sigma^+n channel was found to be much smaller than a previous measurement in that excess energy region. The data together with previous results at higher energies are compatible with a phase space dependence.Comment: accepted by Phys. lett. B some typos correcte

    High resolution study of the Lambda p final state interaction in the reaction p + p -> K+ + (Lambda p)

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    The reaction pp -> K+ + (Lambda p) was measured at Tp=1.953 GeV and Theta = 0 deg with a high missing mass resolution in order to study the Lambda p final state interaction. The large final state enhancement near the Lambda p threshold can be described using the standard Jost-function approach. The singlet and triplet scattering lengths and effective ranges are deduced by fitting simultaneously the Lambda p invariant mass spectrum and the total cross section data of the free Lambda p scattering.Comment: submitted to Physics Letters B, 10 pages, 3 figure

    New Particles from Belle

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    I report recent results on hidden charm spectroscopy from Belle. These include: observation of a near-threshold enhancement in the omega-J/psi invariant mass distribution for exclusive B-->K omega J/psi decays; evidence for the decay X(3872)-->pi+pi-pi0 J/psi, where the pi+pi-pi0 invariant mass distribution has a strong peak between 750 MeV and the kinematic limit of 775 MeV, suggesting that the process is dominated by the sub-threshold decay X-->omega J/psi; and the observation of a peak near 3940 MeV in the J/psi recoil mass spectrum for the inclusive continuum process e+e- --> J/psi X. The results are based on a study of a 287 fb-1 sample of e+e- annihilation data collected at center- of-mass energies around the Upsilon(4S) in the Belle detector at the KEKB collider.Comment: 10 pages 12 figures. Invited talk at the 1st meeting of the APS Topical Group on Hadronic Physics, Fermilab, October 24-26, 2004; revised to correct some reference

    Measurement of shower development and its Moli\`ere radius with a four-plane LumiCal test set-up

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    A prototype of a luminometer, designed for a future e+e- collider detector, and consisting at present of a four-plane module, was tested in the CERN PS accelerator T9 beam. The objective of this beam test was to demonstrate a multi-plane tungsten/silicon operation, to study the development of the electromagnetic shower and to compare it with MC simulations. The Moli\`ere radius has been determined to be 24.0 +/- 0.6 (stat.) +/- 1.5 (syst.) mm using a parametrization of the shower shape. Very good agreement was found between data and a detailed Geant4 simulation.Comment: Paper published in Eur. Phys. J., includes 25 figures and 3 Table

    Detailed comparison of the pp -> \pi^+pn and pp -> \pi^+d reactions at 951 MeV

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    The positively charged pions produced in proton-proton collisions at a beam momentum of 1640 MeV/c were measured in the forward direction with a high resolution magnetic spectrograph. The missing mass distribution shows the bound state (deuteron) clearly separated from the pnpn continuum. Despite the very good resolution, there is no evidence for any significant production of the pnpn system in the spin-singlet state. However, the σ(ppπ+pn)/σ(ppπ+d)\sigma(pp\to \pi^+pn)/\sigma(pp\to \pi^+d) cross section ratio is about twice as large as that predicted from SS-wave final-state-interaction theory and it is suggested that this is due to DD-state effects in the pnpn system.Comment: 8 pages, 3 figure
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