| 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. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
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| 7. |
- 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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| 8. |
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| 9. |
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| 10. |
- 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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| 11. |
- 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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| 12. |
- Valastyán, Iván, et al.
(författare)
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A SPECT demonstrator - revival of a gamma camera
- 2006
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 563:1, s. 274-277
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Tidskriftsartikel (refereegranskat)abstract
- A gamma camera has been updated and converted to serve as a demonstrator for educational purposes. The gantry and the camera head were the only part of the system that remained untouched. The main reason for this modernization was to increase the transparency of the gamma camera by partitioning the different logical building blocks of the system and thus providing access for inspection and improvements throughout the chain. New data acquisition and reconstruction software has been installed. By taking these measures, the camera is now used in education and also serves as a platform for tests of new hardware and software solutions. The camera is also used to demonstrate 3D (SPECT) imaging by collecting 2D projections from a rotatable cylindrical phantom. Since the camera head is not attached mechanically to the phantom, the effect of misalignment between the head and the rotation axis of the phantom can be studied. (c) 2006 Elsevier B.V. All rights reserved.
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| 13. |
- 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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| 14. |
- 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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| 15. |
- Valastyán, Iván, et al.
(författare)
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Full 3-D cluster-based iterative image reconstruction tool for a small animal PET camera
- 2007
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 571:1-2, s. 219-222
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Tidskriftsartikel (refereegranskat)abstract
- Iterative reconstruction methods are commonly used to obtain images with high resolution and good signal-to-noise ratio in nuclear imaging. The aim of this work was to develop a scalable, fast, cluster based, fully 3-D iterative image reconstruction package for our small animal PET camera, the miniPET. The reconstruction package is developed to determine the 3-D radioactivity distribution from list mode type of data sets and it can also simulate noise-free projections of digital phantoms. We separated the system matrix generation and the fully 3-D iterative reconstruction process. As the detector geometry is fixed for a given camera, the system matrix describing this geometry is calculated only once and used for every image reconstruction, making the process much faster. The Poisson and the random noise sensitivity of the ML-EM iterative algorithm were studied for our small animal PET system with the help of the simulation and reconstruction tool. The reconstruction tool has also been tested with data collected by the miniPET from a line and a cylinder shaped phantom and also a rat.
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| 16. |
- Valastyán, Iván, et al.
(författare)
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Validation of an iterative reconstruction for a mobile tomographic gamma camera system - The Cardiotom
- 2007
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 580:2, s. 1097-1100
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Tidskriftsartikel (refereegranskat)abstract
- The Cardiotom is a mobile gamma camera that uses ectomography, an alternative method of acquisition to SPECT. It is designed for early diagnosis of myocardial and cerebral infarctions in the emergency room. Ectomography is a limited view angle method, using a rotating slant hole collimator and a stationary camera head, to acquire projection images. The aim of this work was to validate a fully 3D ML-EM iterative reconstruction algorithm for the Cardiotom. Validation measurements were performed with Tc-99m point sources. Resolution in the reconstructed volume was determined in X, Y. and Z directions from the point spread functions. The results were compared with the values for the formerly used filtered back projection (FBP). The new reconstruction algorithm provides greatly improved depth resolution with respect to the FBP method previously implemented on the Cardiotom. Furthermore, for clinical examinations, images can be available for interpretation within 15 min of the injection, therefore, valuable information can be obtained without delaying treatment of the patient. (c) 2007 Elsevier B.V. All rights reserved.
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| 17. |
- Adelfalk, C, et al.
(författare)
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Cohesin SMC1beta protects telomeres in meiocytes
- 2009
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Ingår i: The Journal of cell biology. - : Rockefeller University Press. - 1540-8140 .- 0021-9525. ; 187:2, s. 185-199
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Tidskriftsartikel (refereegranskat)abstract
- Meiosis-specific mammalian cohesin SMC1β is required for complete sister chromatid cohesion and proper axes/loop structure of axial elements (AEs) and synaptonemal complexes (SCs). During prophase I, telomeres attach to the nuclear envelope (NE), but in Smc1β−/− meiocytes, one fifth of their telomeres fail to attach. This study reveals that SMC1β serves a specific role at telomeres, which is independent of its role in determining AE/SC length and loop extension. SMC1β is necessary to prevent telomere shortening, and SMC3, present in all known cohesin complexes, properly localizes to telomeres only if SMC1β is present. Very prominently, telomeres in Smc1β−/− spermatocytes and oocytes loose their structural integrity and suffer a range of abnormalities. These include disconnection from SCs and formation of large telomeric protein–DNA extensions, extended telomere bridges between SCs, ring-like chromosomes, intrachromosomal telomeric repeats, and a reduction of SUN1 foci in the NE. We suggest that a telomere structure protected from DNA rearrangements depends on SMC1β.
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| 18. |
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| 19. |
- Dénes, E., et al.
(författare)
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Radiation tolerance qualification tests of the final source interface unit for the ALICE experiment for the ALICE collaboration
- 2007
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Ingår i: Proceedings - 12th Workshop on Electronics for LHC and Future Experiments, LECC 2006. - : CERN. ; , s. 438-441
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Konferensbidrag (refereegranskat)abstract
- The ALICE Detector Data Link (DDL) is a high-speed optical link designed to interface the readout electronics of ALICE sub-detectors to the DAQ computers. The Source Interface Unit (SIU) of the DDL will operate in radiation environment. Previous tests showed that a configuration loss of SRAM-based FPGA devices may happen and the frequency of undetected data errors in the FPGA user memory area is also not acceptable. Therefore, we redesigned the SIU card using another FPGA based on flash technology. In order to detect bit errors in the user memory we added parity check logic to the design. The new SIU has been extensively tested using neutron and proton irradiation to verify its radiation tolerance. In this paper we summarize the design changes, introduce the final design, and the results of the radiation tolerance measurements on the final card.
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| 20. |
- Dénes, E., et al.
(författare)
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Radiation tolerant source interface unit for the ALICE experiment
- 2005
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Ingår i: Proceedings - 11th Workshop on Electronics for LHC and Future Experiments, LECC 2005. - : CERN. ; , s. 291-293
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Konferensbidrag (refereegranskat)abstract
- The ALICE Detector Data Link (DDL) is a high-speed optical link designed to interface the readout electronics of ALICE sub-detectors to the DAQ computers. The Source Interface Unit (SIU) of the DDL will operate in radiation environment. Tests showed that configuration loss of the Altera APEX II FPGA device used earlier on the DDL SIU card is only marginally acceptable. We developed a new version of the SIU card using Actel ProASIC+ device based on flash memory technology. The new SIU card has been extensively tested using neutron and proton irradiation. In this paper we present the SIU card and describe the results of irradiation measurements.
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| 21. |
- Novák, D., et al.
(författare)
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Component tests for the PRISMA spacecraft
- 2007
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Ingår i: RADECS 2007. - : IEEE. - 9781424417049 ; , s. 595-598
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Konferensbidrag (refereegranskat)abstract
- TID and proton tests are reported on some COTS components for the PRISMA satellite project. TID test level was more than 20 krad and 170 MeV protons were used for the single event tests.
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| 22. |
- 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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| 23. |
- Raska, Milan, et al.
(författare)
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Identification and characterization of CMP-NeuAc:GalNAc-IgA1 alpha2,6-sialyltransferase in IgA1-producing cells
- 2007
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 1089-8638 .- 0022-2836. ; 369:1, s. 69-78
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Tidskriftsartikel (refereegranskat)abstract
- Glycosylation defects occur in several human diseases. In IgA nephropathy, IgA1 contains O-glycans that are galactose-deficient and consist mostly of core 1 alpha2,6 sialylated N-acetylgalactosamine, a configuration suspected to prevent beta1,3 galactosylation. We confirmed the same aberrancy in IgA1 secreted by the human DAKIKI B cell line. Biochemical assays indicated CMP-NeuAc:GalNAc-IgA1 alpha2,6-sialyltransferase activity in this cell line. However, a candidate enzyme, ST6-GalNAcI, was not transcribed in DAKIKI cells, B cells isolated from blood, or Epstein-Barr virus (EBV)-immortalized IgA1-producing cells from the blood of IgAN patients and healthy controls. Instead, ST6-GalNAcII transcription was detected at a high level. Expression of the ST6-GalNAcII gene and activity of the CMP-NeuAc:GalNAc-IgA1 alpha2,6-sialyltransferase were higher in IgA1-producing cell lines from IgAN patients than in such cells from healthy controls. These data are the first evidence that human cells that lack ST6-GalNAcI can sialylate core 1 GalNAc-Ser/Thr.
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| 24. |
- Valastyán, Iván, et al.
(författare)
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Gated tomographic imaging in ectomography using a dynamic heart phantom
- 2007
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Ingår i: Nuclear Science Symposium Conference Record, 2007. NSS '07. IEEE. - : IEEE. - 9781424409228 ; , s. 3414-3417
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Konferensbidrag (refereegranskat)abstract
- A new computer controlled dynamic heart phantom and the connection of an ECG unit to a tomographic gamma camera system, developed for ectomographic imaging, is presented. The phantom is used for validation of the camera. Measurements were performed to test the phantom as well as to study the feasibility of gated imaging in ectomography. The camera is intended for early diagnosis of myocardial and cerebral infarctions.
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| 25. |
- Verbeeck, J., et al.
(författare)
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Optimal aperture sizes and positions for EMCD experiments
- 2008
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Ingår i: Ultramicroscopy. - : Elsevier BV. - 0304-3991 .- 1879-2723. ; 108:9, s. 865-872
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Tidskriftsartikel (refereegranskat)abstract
- The signal-to-noise ratio (SNR) in energy-loss magnetic chiral dichroism (EMCD)-the equivalent of Xray magnetic circular dichroism (XMCD) in the electron microscope-is optimized with respect to the detector shape, size and position. We show that an important increase in SNR over previous experiments can be obtained when taking much larger detector sizes. We determine the ideal shape of the detector but also show that round apertures are a good compromise if placed in their optimal position. We develop the theory for a simple analytical description of the EMCD experiment and then apply it to dynamical multibeam Bloch wave calculations and to an experimental data set. In all cases it is shown that a significant and welcome improvement of the SNR is possible.
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| 26. |
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