| 1. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 2. |
- Hegyesi, G., et al.
(författare)
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Ethernet based distributed data acquisition system for a small animal PET
- 2006
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Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 53:4, s. 2112-2117
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Tidskriftsartikel (refereegranskat)abstract
- We report on the design of a small animal PET scanner being developed at our institutes. The existing setup is the first version of the miniPET machine consisting of four detector modules. Each detector module consists of an 8 x 8 LSO scintillator crystal block, a position sensitive photomultiplier, a digitizer including a digital signal processing board and an Ethernet interface board. There is no hardware coincidence detection implemented in the system and coincidence is determined based on a time stamp attached to every event by a digital CFD algorithm. The algorithm is implemented in the digital signal processing board and generates a time stamp with a coincidence resolution of less than 2 us. The data acquisition system is based on Ethernet network and is highly scalable in size and performance.
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| 3. |
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| 4. |
- Imrek, J., et al.
(författare)
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Internals and evaluation of the miniPET-II detector module
- 2007
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Ingår i: 2007 IEEE Nuclear Science Symposium Conference Record. - 1424409233 - 9781424409235 ; , s. 2930-2932
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Konferensbidrag (refereegranskat)abstract
- We report on the architecture of the System-on-Module (SoM) developed by our group for miniPET-II, the second version of our small animal PET scanner. The paper describes the hardware and software implementation details of the SoM we realized inside the miniPET-II detector module, the embedded Linux operation system, and the the initial results of bandwidth test measurements on the assembled SoM. Detailed description is given on the interfacing of the updated miniPET IP Core to the SoM, on the efficient data transfer method that implements device-to-device DMA transfer, and on the usage of User Datagram Protocol (UDP/IP) for high speed data transfer.
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| 5. |
- Kis, S. A., et al.
(författare)
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Comparison of Monte Carlo simulated and measured performance parameters of miniPET scanner
- 2007
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 571:02-jan, s. 449-452
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Tidskriftsartikel (refereegranskat)abstract
- In vivo imaging of small laboratory animals is a valuable tool in the development of new drugs. For this purpose, miniPET, an easy to scale modular small animal PET camera has been developed at our institutes. The system has four modules, which makes it possible to rotate the whole detector system around the axis of the field of view. Data collection and image reconstruction are performed using a data acquisition (DAQ) module with Ethernet communication facility and a computer cluster of commercial PCs. Performance tests were carried out to deter-mine system parameters, such as energy resolution, sensitivity and noise equivalent count rate. A modified GEANT4-based GATE Monte Carlo software package was used to simulate PET data analogous to those of the performance measurements. GATE was run on a Linux cluster of 10 processors (64 bit, Xeon with 3.0 GHz) and controlled by a SUN grid engine. The application of this special computer cluster reduced the time necessary for the simulations by an order of magnitude. The simulated energy spectra, maximum rate of true coincidences and sensitivity of the camera were in good agreement with the measured parameters.
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| 6. |
- Kis, S. A., et al.
(författare)
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Performance Characteristics of a miniPET Scanner Dedicated to Small Animal Imaging
- 2005
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Ingår i: 2005 IEEE Nuclear Science Symposium Conference Record. - 0780392213 - 9780780392212 ; , s. 1645-1648
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Konferensbidrag (refereegranskat)abstract
- An easy to scale up modular PET scanner was developed for imaging small animals. Energy resolution, spatial resolution and count rate performance were determined as system parameters. The configuration provided an average energy resolution of 19.6 % and the image resolution ranges was 1.5 to 2.3 mm in radial direction. The sensitivity of the miniPET was 1.08 cps/kBq as determined using a point source. In addition, results of rat brain scan performed with FDG are given to characterize imaging capability of the system. The displayed data document that the miniPET scanner supports good quality brain imaging of small animals.
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| 7. |
- Novák, D., et al.
(författare)
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In flight SEU tests on the European SMART-1 spacecraft
- 2005
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Ingår i: Proceedings of the European Conference on Radiation and its Effects on Components and Systems, RADECS. - 0780395018 - 9780780395015 ; , s. PH11-PH13
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Konferensbidrag (refereegranskat)abstract
- The SMART-I satellite launched by the European Space Agency has traveled to an orbit around the Moon driven by its own ion engine. Because of the characteristics of the ion engine mission required many revolutions to reach the Moon and the time to pass through the radiation belts around the Earth was significant. The spacecraft is exposed to solar protons throughout its mission. In advance the flight in-beam test data was collected to asses the radiation hardness properties of an SRAM, one of the components of the system unit of the satellite. Single Event Upset data is available for this component and Solar Proton Flux was measured by the GOES satellite in Geosynchronous orbit. The aim of this work is to compare the predictions of the in-beam tests and the effects of the in space irradiation of SRAM circuits on board.
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| 8. |
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| 9. |
- Buker, P, et al.
(författare)
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Comparison of different stomatal conductance algorithms for ozone flux modelling
- 2005
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Ingår i: UNECE – Workshop “Critical Levels of Ozone: Further applying and developing the flux-based concept”, Obergurgl, 15-19 November 2005.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Two widely used algorithms for modelling stomatal conductance (gs) were compared in order to evaluate the approach leading to the most realistic predictions of stomatal fluxes to vegetated surfaces: a multiplicative algorithm initially developed by Jarvis (1976) and refined by Emberson et al. (2000) (DO3SE ) and a photosynthesis-based Ball&Berry-type algorithm developed by Nikolov et al. (1995) (LEAFC3). Both models were parameterised for several crop and tree species (wheat, grapevine, Scots pine, beech and birch) and have been applied to various datasets – with the main focus on wheat - representing different European regions (North, Central and South Europe). A sensitivity analysis has been carried out for both models to evaluate the dependence of gs on the meteorological parameters temperature, photosynthetic active radiation and vapour pressure deficit. Furthermore, in order to test whether a general species-specific parameterisation can account for differences in gs due to plants growing under different climatic conditions throughout Europe, the models have been re-parameterised for local meteorological conditions. A direct comparison of both models showed that the net photosynthetic-based model required more detailed meteorological (e.g. ambient CO2-concentration, dew-point temperature) and plant-physiological (e.g. Vcmax and Jmax) input parameters while not delivering a substantially higher R2 when comparing measured and modelled gs. The relative weakness of the multiplicative model lies in its dependence on the maximum stomatal conductance (gmax), whereas the photosynthesis-based model is not taking into account phenology-related changes in gs. Furthermore, the results show that an equally close relationship between gs and net photosynthetic rate throughout the entire growing season is questionable. We conclude that the multiplicative approach is favourable for calculating stomatal fluxes on a wider scale (e.g. within EMEP-deposition model), whereas the photosynthesis-based approach is a potential alternative for modelling fluxes on a local scale.
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| 10. |
- Emri, M., et al.
(författare)
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Software development framework supporting multimodal tomographic imaging
- 2007
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Ingår i: 2006 IEEE Nuclear Science Symposium Conference Record. - : IEEE. - 1424405610 - 9781424405619 ; , s. 1857-1859
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Konferensbidrag (refereegranskat)abstract
- Engineers specialized in multimodal tomography regularly face a wide scale of programming tasks requiring an integrated software system to ensure cost efficiency. Accordingly, a software development framework has been worked out comprising libraries for cluster-based data acquisition, image reconstruction, management of data files and complex multimodal volumetric visualization. This framework enabled us to develop complex software for our miniPET project [1]. This software contains a graphical application integrating data acquisition, cluster monitoring, event sorting, image reconstruction, interactive image processing tools for advanced multimodal visualization. It also contains utilities to solve these tasks without graphical user interface. The components of our acquisition program can run on embedded Linux systems making new ways to develop any other types of data acquisition software that uses embedded Linux systems. A versatile development framework is developed containing specific libraries and special file formats that support multimodal tomography. This framework was successfully used to elaborate our complex miniPET software.
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| 11. |
- Hamer, G, et al.
(författare)
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Characterization of a novel meiosis-specific protein within the central element of the synaptonemal complex
- 2006
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Ingår i: Journal of cell science. - : The Company of Biologists. - 0021-9533 .- 1477-9137. ; 119:19Pt 19, s. 4025-4032
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Tidskriftsartikel (refereegranskat)abstract
- During the first meiotic prophase, alignment and synapsis of the homologous chromosomes are mediated by the synaptonemal complex. Incorrect assembly of this complex results in cell death, impaired meiotic recombination and formation of aneuploid germ cells. We have identified a novel mouse meiosis-specific protein, TEX12, and shown it to be a component of the central element structure of the synaptonemal complex at synapsed homologous chromosomes. Only two other central element proteins, SYCE1 and SYCE2, have been identified to date and, using several mouse knockout models, we show that these proteins and TEX12 specifically depend on the synaptonemal transverse filament protein SYCP1 for localization to the meiotic chromosomes. Additionally, we show that TEX12 exactly co-localized with SYCE2, having the same, often punctate, localization pattern. SYCE1, on the other hand, co-localized with SYCP1 and these proteins displayed the same more continuous expression pattern. These co-localization studies were confirmed by co-immunoprecipitation experiments that showed that TEX12 specifically co-precipitated with SYCE2. Our results suggest a molecular network within the central elements, in which TEX12 and SYCE2 form a complex that interacts with SYCE1. SYCE1 interacts more directly with SYCP1 and could thus anchor the central element proteins to the transverse filaments.
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| 12. |
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| 13. |
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| 14. |
- Imrek, J., et al.
(författare)
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Development of an improved detector module for miniPET-II
- 2007
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Ingår i: 2006 IEEE Nuclear Science Symposium Conference Record. - : IEEE. - 1424405610 - 9781424405619 ; , s. 3037-3040
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Konferensbidrag (refereegranskat)abstract
- We present a new detector module developed for miniPET-II, the second generation of the miniPET small animal PET scanners. The improved module features new hardware components for better performance: LySO crystal material, increased number of crystal segments, Hamamatsu H9500 PSPMT, Xilinx Virtex-4 FPGA and Gigabit Ethernet. However, the principle of operation is the same: no hardware coincidence detection is implemented, data is acquired in list mode and transfered over an Ethernet network. The resulting new module is more suitable for full ring configurations.
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| 15. |
- Simon, A., et al.
(författare)
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High spatial resolution measurement of depth-of-interaction of a PET LSO crystal
- 2005
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 546:1-2, s. 33-36
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Tidskriftsartikel (refereegranskat)abstract
- A new type of experimental technique to investigate the depth- of-interaction (DOI) dependence in small scintillator elements designed for high-resolution animal PET is tested. An Oxford-type nuclear microprobe was used to irradiate a lutetium oxyorthosilicate (LSO) crystal (2 x 2 x 10 mm) with a highly focused, (few micrometers diam.), 2 MeV He+ beam. Pulse height spectra from a PMT attached to one end of the LSO crystal were collected in list mode. By scanning the beam over the crystal high-resolution 2D-images are generated and thus the DOI effect in the scintillator could be investigated. The obtained results of the overall DOI dependence confirm previous findings using gamma-rays. Since the present experimental setup allows obtaining data with several orders of magnitude better spatial resolution than with collimated gamma-beam, the method can be applied for variety of problems where high spatial resolution is required.
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| 16. |
- Valastyán, Iván, et al.
(författare)
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Data acquisition and image reconstruction systems from the MiniPET scanners to the CARDIOTOM camera
- 2007
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Ingår i: Nuclear Physics Methods And Accelerators In Biology And Medicine. - : American Institute of Physics (AIP). - 9780735404724 ; , s. 282-283
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Bokkapitel (refereegranskat)abstract
- Nuclear imaging devices play an important role in medical diagnosis as well as drug research. The first and second generation data acquisition systems and the image reconstruction library developed provide a unified hardware and software platform for the miniPET-I, miniPET-II small animal PET scanners and for the CARDIOTOM(TM).
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| 17. |
- Valastyán, Iván, et al.
(författare)
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Experimental scanner setup from miniPET II detector module
- 2009
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Ingår i: 2008 IEEE Nuclear Science SYmposium Conference Record. - 9781424427147 ; , s. 3121-3124
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The PET technique is widely used in human clinical studies and recent developments of image resolution has made it suitable for small animal research. The second generation of our PET scanner consists of 12 detector modules and has a field of view large enough to image mice and rats. Parameters of the incoming data are extracted by Digital Signal Processing in the detector modules and a System-on-Module is used to transmit the data through an Ethernet network for storage and reconstruction. The experimental scanner setup described in this paper was constructed in order to investigate the applicability of the developed detector modules in a full ring small animal PET camera. The preliminary results of the system are also presented.
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| 18. |
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| 19. |
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