2,279 research outputs found

    Optimization of Far-Field Antenna Range

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    Measurements of test antennas are performed on antenna ranges. The operated microwave far-field outdoor range was built-up in 1970’s and therefore it was not appropriate for the today measurements. Thus, it was decided to perform the complete reconstruction and testing. Some results of new ample measurement campaign are just given. The optimization of antenna range using merely measurement is very inefficient, and therefore that is done by numerical simulations. Consequently the paper surveys briefly electromagnetic wave propagation over irregular terrain. The physical optics approximation of vector problem was chosen. That allows the comparison of selected numerical simulations and measurements for the reconstructed far-field range. A possibility of antenna range optimizing by using numerical simulation considering various constraints is verified

    The electric form factor of the neutron and its chiral content

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    Considering the nucleon as a system of confined valence quarks surrounded by pions we derive a Galster-like parameterization of the neutron electric form factor GEnG_E^n. Furthermore, we show that the proposed parameterization can be linked to properties of the pion cloud. By this, the high quality data for the pion form factor can be used in predictions of GEnG_E^n in the low Q2Q^2 region, where the direct double polarization measurements are not available.Comment: 11 pages, 3 figure

    Group F Streptococcal Bacteremia Complicating a Bartholin's Abscess

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    Background: Group F streptococci are Gram-positive cocci typically isolated from wound infections and abscesses. Bacteremia with group F streptococcus is uncommon, and the lower gynecologic tract has not been reported as a source. We report a case of a Bartholin's abscess leading to group F streptococcal bacteremia. Case: A 31-year-old female noted fever and rigors 30 min after manipulation of a 3-day-old vulvar abscess. An empty Bartholin's gland abscess was found on examination, and blood cultures grew β-hemolytic group F streptococci. The patient was treated with ampicillin/sulbactam, symptoms improved, and follow-up blood cultures revealed no growth. Conclusion: Group F streptococci are known to inhabit various body sites and have a predilection for forming abscesses; however, bacteremia is infrequent. They have occasionally been identified in true infections of the genitourinary tract but only very rarely in Bartholin's abscesses. This case of group F streptococcal bacteremia following self-drainage of a Bartholin's abscess constitutes the first such description in the medical literature

    Fostering European Collaborations: EUFRAT and work done at the accelerator facilities of JRC-IRMM

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    The European Commission via the General Directorate RTD in its different Framework Programs supported collaborations of member state institutions dealing with nuclear data. The projects EFNUDAT, ERINDA, CHANDA and EUFRAT all have in common Transnational Access Activities (TAA) to partner institutions. Within the past 10 years the collaborations have grown and in CHANDA now 35 partners are involved of which 16 offer TAA to their facilities. Since June 2014 JRC-IRMM, one of the driving forces behind the TAA, launched its own TAA project EUFRAT to foster collaborations with member states institutions. The calls for proposals are open ended with a deadline twice a year. A Project Advisory Committee discusses the proposals and decides on about approval. Financial support is given to approved proposals for two scientists. So far two calls have been evaluated with a request for access totalling more than 5000 h. Examples of proposals at the accelerator facilities at the JRC-IRMM are presented showing the multitude of possibilities using the nuclear facilities at the JRC-IRMM

    Thermal and electromagnetic properties of 166-Er and 167-Er

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    The primary gamma-ray spectra of 166-Er and 167-Er are deduced from the (3-He,alpha gamma) and (3-He,3-He' gamma) reaction, respectively, enabling a simultaneous extraction of the level density and the gamma-ray strength function. Entropy, temperature and heat capacity are deduced from the level density within the micro-canonical and the canonical ensemble, displaying signals of a phase-like transition from the pair-correlated ground state to an uncorrelated state at Tc=0.5 MeV. The gamma-ray strength function displays a bump around E-gamma=3 MeV, interpreted as the pygmy resonance.Comment: 21 pages including 2 tables and 11 figure

    Level densities and Îł\gamma-strength functions in 148,149^{148,149}Sm

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    The level densities and Îł\gamma-strength functions of the weakly deformed 148^{148}Sm and 149^{149}Sm nuclei have been extracted. The temperature versus excitation energy curve, derived within the framework of the micro canonical ensemble, shows structures, which we associate with the break up of Cooper pairs. The nuclear heat capacity is deduced within the framework of both the micro canonical and the canonical ensemble. We observe negative heat capacity in the micro canonical ensemble whereas the canonical heat capacity exhibits an S-shape as function of temperature, both signals of a phase transition. The structures in the Îł\gamma-strength functions are discussed in terms of the pygmy resonance and the scissors mode built on exited states. The samarium results are compared with data for the well deformed 161,162^{161,162}Dy, 166,167^{166,167}Er and 171,172^{171,172}Yb isotopes and with data from (n,Îł\gamma)-experiments and giant dipole resonance studies.Comment: 12 figure

    Encoded physics knowledge in checking codes for nuclear cross section libraries at Los Alamos

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    Checking procedures for processed nuclear data at Los Alamos are described. Both continuous energy and multi-group nuclear data are verified by locally developed checking codes which use basic physics knowledge and common-sense rules. A list of nuclear data problems which have been identified with help of these checking codes is also given
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