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Sökning: WFRF:(Bäck Torbjörn) > (2005-2009)

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1.
  • Andgren, Karin, et al. (författare)
  • gamma-ray spectroscopy of At-197
  • 2008
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 78:4, s. 044328-1-044328-8
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states of the extremely neutron-deficient nucleus At-197 have been studied in an in-beam experiment using the fusion-evaporation reaction Sn-118(Kr-82,p2n)At-197. gamma rays belonging to At-197 feeding the I-pi=(9/2(-)) ground state, as well as gamma rays feeding the 311-keV I-pi=(13/2(+)) isomer, decaying via the emission of gamma rays, and the 52-keV I-pi=(1/2(+)) alpha-decaying isomer have been identified using the recoil-alpha-decay tagging technique. Total Routhian surface calculations predict a near-spherical shape for the (9/2(-)) ground state and oblate shapes with beta(2) around -0.2 for the (1/2(+)) and the (13/2(+)) states. These predictions agree with our experimental findings.
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2.
  • Bäck, Henry, 1947, et al. (författare)
  • Den svenska politiken : Struktur, processer och resultat
  • 2006
  • Bok (övrigt vetenskapligt/konstnärligt)abstract
    • I Den svenska politiken ges en bred översikt över statsskicket och politiken. Med utgångspunkt i stats- och samhällsvetenskaplig forskning beskrivs och analyseras staten, EU, kommuner och landsting. Det politiska systemet gör det möjligt att fatta gemensamma beslut och skrida till gemensam handling i samhället. Till skillnad från andra system för gemensamt handlande verkar politiken genom att använda makt. För att kunna fånga maktutövningen i ett politiskt system krävs analytiska instrument i form av samhällsvetenskaplig teori. I boken behandlas särskilt det politiska systemets inbyggda kontrollmekanismer och den politiska processen. Formandet av den offentliga politiken illustreras med några centrala politikområden i den moderna svenska politiken. Här beskrivs och analyseras både det formella normativa ramverket och ”hur det verkligen går till”. För att begripa dagens svenska politik behöver vi kunna göra jämförelser i både tid och rum, och därför anläggs ett historiskt perspektiv och görs utblickar på andra länder.
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3.
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4.
  • Hadinia, Baharak, et al. (författare)
  • Identification of gamma rays from Au-172 and alpha decays of Au-172, Ir-168, and Re-164
  • 2009
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 80:6, s. 064310-
  • Tidskriftsartikel (refereegranskat)abstract
    • The very neutron deficient odd-odd nucleus Au-172 was studied in reactions of 342 and 348 MeV Kr-78 beams with an isotopically enriched Ru-96 target. The alpha decays previously reported for Au-172 were confirmed and the decay chain extended down to Tm-152 through the discovery of a new alpha-decaying state in Re-164 [E-alpha=5623(10) keV; t(1/2)=864(-110)(+150) ms; b(alpha)=3(1)%]. Fine structure in these alpha decays of Au-172 and Ir-168 were identified. A new alpha-decaying state was also observed and assigned as the ground state in Au-172 [E-alpha=6762(10) keV; t(1/2)=22(-5)(+6) ms]. This decay chain was also correlated down to Tm-152 through previously reported alpha decays. Prompt gamma rays from excited states in Au-172 have been identified using the recoil-decay tagging technique. The partial level scheme constructed for Au-172 indicates that it has an irregular structure. Possible configurations of the alpha-decaying states in Au-172 are discussed in terms of the systematics of nuclei in this region and total Routhian surface calculations.
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5.
  • Hadinia, Baharak, et al. (författare)
  • In-beam gamma-ray and alpha-decay spectroscopy of 170Ir
  • 2007
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 76:4, s. 044312-1-044312-8
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in the highly neutron deficient odd-odd nucleus Ir-170 have been investigated. The experiment was performed using the Sn-112(Ni-60, pn)Ir-170 reaction and employing the recoil-decay tagging technique. Gamma rays were detected using the JUROGAM gamma-ray spectrometer and those belonging to Ir-170 were selected based on recoil identification provided by the RITU gas-filled recoil separator and the GREAT spectrometer at the RITU focal plane. A partial level scheme of Ir-170 is presented for the first time. New alpha-decay branches are assigned to Ir-170 and a tentative level structure for Re-166 is deduced from a study of the alpha-decay fine structure and the associated alpha-gamma correlations.
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6.
  • Joss, D. T., et al. (författare)
  • Probing structural changes in the very neutron-deficient Os isotopes with recoil-decay tagging
  • 2005
  • Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 31:10, s. S1593-S1598
  • Tidskriftsartikel (refereegranskat)abstract
    • In recent years, the exploitation of the iecoil-decay tagging (RDT) technique with,large arrays of germanium detectors has revealed much information about the structure of heavy nuclei approaching the proton drip line. The yrast bands of the N <= 93 osmium isotopes have been identified in a campaign of tagging experiments using various spectrometer arrays coupled to the RITU gas-filled separator based at the University of Jyvaskyla. Trends in the yrast state excitation energies have indicated a transition from gamma-soft triaxial to near-spherical shapes with decreasing neutron number. Recent experimental results for Os-162 obtained with the JUROGAM and GREAT spectrometers also indicate the importance of configurations involving the h(9/2) neutron states as the N = Z 82 shell gaps are approached.
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7.
  • Lindaräng, Ingemar, 1938- (författare)
  • Helgonbruk i moderniseringstider : Bruket av Birgitta- och Olavstraditionerna i samband med minnesfiranden i Sverige och Norge 1891–2005
  • 2007
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Avhandlingen syftar till att jämföra och förstå variationen av historiebruk i samband med minnesfiranden av heliga Birgitta i Sverige och hellig Olav i Norge med fokus på olika aktörers motiv, resurser, budskap och identitetsskapande processer i en tid av modernisering och sekularisering.Under den katolska medeltiden var helgonfiranden vanliga, men de förbjöds i samband med reformationen. I slutet av 1800-talet, samtidigt med omvandligen av de båda länderna till moderna industri-samhällen, väcktes återigen intresset för dessa helgonfiranden. Det var bland annat liberala rörelser som brukade helgonen för att förankra de förändringsprocesser, som man ville göra, i historien. Heliga Birgitta användes i Sverige av kvinnorörelsen som en medeltida förebild i kampen för ökat inflytande i samhälle. Hellig Olav blev under samma tid i Norge en symbol för nationell självständighet i kampen för upplösning av unionen med Sverige. För den katolska kyrkan, som under 1800-talet åter fick verka i de båda protestantiska länderna, blev bruken av heliga Birgitta och hellig Olav en historisk länk till medeltidens kyrka och för att därigenom legitimera sin verksamhet, medan de lutherska kyrkorna tog avstånd från dessa firanden.I avhandlingen följs utvecklingen av dessa minnesfiranden i relation till samhällsförändringarna. På 1920-talet väcktes även de lutherska kyrkornas och det offentliga samhällets intresse för Birgitta- och Olavjubileer. Genom det ekumeniska genombrottet på 1970-talet och kyrkornas ökade engagemang i sociala och kulturella frågor efter Andra Vatikankonciliet blev jubileerna arenor då den ekumeniska gemenskapen och kulturella öppenheten synliggjordes vilket bidrog till att bredda intresset för dessa firanden. Detta förstärktes i tiden kring sekelskiftet 2000 samtidigt som engagemanget från det offent-liga samhället och kommersiella aktörer ökade.Författaren ser utvecklingen av dessa jubileer som uttryck för olika identitetsprocesser. Hellig Olavs roll som en nationell symbol har varit mycket tydlig medan heliga Birgitta framför allt symboli-serat Sveriges internationella roll. Orter som varit viktiga i helgonberättelserna har brukat helgontradi-tionerna i lokala identitetsprocesser vilket allt mer betonats genom turismens ökade betydelse. Jubile-erna har även öppnat för individuella identitetsprocesser med helgonen som religiösa förebilder. För kvinnorörelser har heliga Birgitta genomgående under åren framförts som en viktig förebild.I avhandlingen diskuteras även hur det ökade intresset för firanden av heliga Birgitta och hellig Olav förhåller sig till teorin om den ökade sekulariseringen i det moderna samhället. Med stöd av religionssociologisk forskning diskuteras detta samband. En religiös pluralism kan öka det religiösa utbudet och därmed även ”konsumtionen” av religion. Många kombinerar även det moderna samhällets rationalitet med irrationella föreställningar och upplevelser.
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8.
  • Mach, H., et al. (författare)
  • Application of ultra-fast timing techniques to the study of exotic and weakly produced nuclei
  • 2005
  • Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 31:10, s. S1421-S1426
  • Tidskriftsartikel (refereegranskat)abstract
    • Ultra-fast time-delayed techniques have been recently applied in a number of studies where exotic nuclei were identified using advanced selection techniques. These include large Compton-suppressed Ge arrays, in-flight separators or recoil separators. Some of the new results are discussed in this presentation. Besides the results for Mg-32 and Pd-96, they include the first determination of the half-life of the 8(+) state in Ge-80, T-1/2 = 2.95(6) ns, and significantly more precise results for Mn-51 (3680 keV level) and V-48 (421 keV level), T-1/2 = 1760(40) ps and T-1/2.
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9.
  • Norén, Torbjörn, 1955- (författare)
  • Clostridium difficile : epidemiology and antibiotic resistance
  • 2006
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Clostridium difficile is a spore-forming toxin-producing intestinal bacterium abundant in soils and waters. This pathogen relies on increased growth by a disturbed intestinal microflora and the production of two cytotoxins, toxin A and toxin B, which may cause anything from mild self-limiting C. difficile associated diarrhea (CDAD) to severe and fatal pseudomembranous colitis (PMC). Typically CDAD following antibiotic therapy is due either to overgrowth of endogenous C. difficile or through spores transmitted from the environment. The hospital setting provides frequent antibiotic use and the source of numerous infective spores from CDAD patients, the environment or nursing staff. Today we experience a 10-fold increase of incidence in the US and Canada (1991-2003) apparently due to a current epidemic C. difficile strain (NAP1/027). Current incidence from Canada is estimated to 156/100 000 compared to 50/100 000 in Sweden 1995. In the following thesis, investigations of CDAD in Örebro County in central Sweden resulted in the discovery an epidemic nosocomial C. difficile strain (SE17, serogroup C), found to be clindamycin-resistant. The majority of the isolates carried a gene (ermB) related to this resitance. We found an overall incidence during 1999-2000 of 97/100 000 or, if including recurrent episodes, 135/100 000 i.e. more than 100% increase since 1995. The incidence among hospitalized individuals was 1300-fold that in the community and 78% of episodes were classified as hospital-associated. This reflects a 37-fold difference in antibiotic consumption, as well as the predominance of the resistant SE17 hospital-associated strain (22% of hospital isolates compared to 6% of community isolates, p=0.008). Only 10% of the recurrent cases were found to be reinfections indicating that CDAD is mainly caused by endogenous strains and not by hospital transmission. Recent reports on failure of standard metronidazole therapy urge for alternative treatment agents and fusidic acid has been proven as effective in the treatment of CDAD. We could verify this, but in both treatment groups we found that persistence of C. difficile isolates post-treatment related to an increased risk of recurrent CDAD compared to the patients who were culture negative at follow-up (p=0.03). Most importantly, 55% of patients with follow-up isolates and who had been treated with fusidic acid, the strains had developed fusidic acid resistance. The corresponding pre-treatment identity of isolate genotype indicated selection of mutants. Relating to the known fusA resistance mechanism in Staphylococcus aureus we used the published sequence for this gene in Clostridium perfringens and found homologous fusA in the sequence of the referent strain C. difficile 630. Comparing fusA of the resistant mutants with the initial wild-type isolates, we identified novel mutations in fusA as the genetic key to fusidic acid resistance in C. difficile.
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10.
  • Norén, Torbjörn, et al. (författare)
  • Frequent emergence of resistance in Clostridium difficile during treatment of C-difficile-associated diarrhea with Fusidic acid
  • 2006
  • Ingår i: Antimicrobial Agents and Chemotherapy. - 0066-4804 .- 1098-6596. ; 50:9, s. 3028-3032
  • Tidskriftsartikel (refereegranskat)abstract
    • Samples from patients with Clostridium difficile-associated diarrhea (CDAD) that were randomized to fusidic acid (n = 59) or metronidazole (n = 55) therapy for 7 days were cultured for Clostridium difficile in feces on days 1, 8 to 13, and 35 to 40. Of the patients who were culture positive only before treatment, 77% (36/47) were permanently cured (no treatment failure and no clinical recurrence), compared to 54% (22/41) of those with persistence of C. difficile at one or both follow-ups (P = 0.03). A similar association between bacterial persistence and a worse outcome of therapy was seen in both treatment groups. Resistance to fusidic acid was found in 1 of 88 pretherapy isolates available, plus in at least 1 subsequent isolate from 55% (11/20) of patients who remained culture-positive after fusidic acid therapy. In 10 of these 11 patients, the resistant follow-up isolate(s) belonged to the same PCR ribotype as the susceptible day 1 isolate, confirming frequent emergence of resistance to fusidic acid during treatment. Despite this, 5 of these 11 patients were permanently cured with fusidic acid, relative to 5 of 9 patients with susceptible C. difficile at follow-up (P = 1.0). None of the 36 PCR ribotypes of C. difficile identified was associated with any particular clinical outcome or emergence of fusidic acid resistance. In conclusion, culture positivity for C. difficile was common after both fusidic acid and metronidazole therapy and was associated with treatment failure or recurrence of CDAD. Development of resistance in C. difficile was frequent in patients given fusidic acid, but it was without apparent negative impact on therapeutic efficacy in the actual CDAD episode.
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11.
  • O'Donnell, D., et al. (författare)
  • First observation of excited states in Hg-175(95)
  • 2009
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 79:5, s. 051304-
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states of the neutron-deficient nucleus Hg-175, populated using fusion-evaporation reactions, are reported for the first time. The spin and parity of the ground state has been determined to be I-pi=7/2(-) through measurements of the alpha decay to the daughter nucleus Pt-171. A structure based on an isomeric state [T-1/2=0.34(3) mu s] with I-pi=13/2(+) and its decay path to the ground state have been established. The observed structures are interpreted in terms of single-particle configurations, and the trends of coexisting shapes in neighboring nuclei are discussed.
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12.
  • Ruchowska, E., et al. (författare)
  • Nuclear structure of Th-229
  • 2006
  • Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 73:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Lifetimes of excited states in Th-229, populated in the beta decay of Ac-229, have been measured using the advanced time-delayed beta gamma gamma(t) method. Half-lives of 14 states have been determined including 11 of them for the first time. Twenty-seven new gamma lines have been introduced into the beta-decay scheme of Ac-229 based on results of gamma gamma coincidence measurements. Reduced transition probabilities have been determined for more than 70 gamma transitions in Th-229. Average parallel to D-0 parallel to values of 0.029(1), 0.077(3), and 0.024(5) e fm have been deduced for the lowest K-pi=1/2(+/-),3/2(+/-), and 5/2(+/-) parity partner bands, respectively. Excited states in Th-229 and experimental transition rates have been interpreted within the quasiparticle-plus-phonon model. The half-life of the 3.5-eV, 3/2(+) isomeric state is predicted to be about 10 h. Potential energy surfaces on the (beta(2),beta(3)) plane for the lowest single quasiparticle configurations in Th-229 have been calculated using the Strutinsky method.
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13.
  • Sandzelius, Mikael, et al. (författare)
  • First identification of excited states in 169Ir
  • 2007
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 75:5, s. 054321-
  • Tidskriftsartikel (refereegranskat)abstract
    • Gamma rays populating the alpha-decaying isomeric state in Ir-169 have been observed for the first time. The experiment employed the recoil-decay tagging method using the JUROGAM gamma-ray spectrometer, the RITU gas-filled recoil separator and the GREAT spectrometer located at the RITU focal plane. The gamma-ray cascade feeding the isomeric alpha-decaying state exhibits a rotational structure consistent with a h(11/2) proton coupled to a triaxially deformed core. The experimental results are compared with predictions from total Routhian surface calculations.
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14.
  • Sandzelius, Mikael, et al. (författare)
  • First observation of excited states in Hg-172
  • 2009
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 79:6, s. 064315-
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in the extremely neutron-deficient isotope Hg-172 have been established for the first time. The Ru-96(Kr-78,2n) reaction was employed to populate excited states in Hg-172 with a cross section sigma approximate to 15 nb. The highly selective recoil-decay tagging (RDT) technique was used to obtain clean in-beam gamma-ray spectra for Hg-172. The yrast ground-state band has tentatively been established up to I=6 h. The data have been interpreted within the framework of total Routhian surface and quasiparticle random phase approximation calculations. .  
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15.
  • Sandzelius, Mikael, et al. (författare)
  • (gamma)-ray spectroscopy of 163Ta
  • 2009
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 80:5, s. 054316-
  • Tidskriftsartikel (refereegranskat)abstract
    • Excited states in Ta-163 have been identified for the first time using the Cd-106(Ni-60,3p) fusion evaporation reaction. gamma rays were detected using the JUROGAM gamma-ray spectrometer and recoil discrimination was achieved using the recoil ion transport unit (RITU) gas-filled separator in conjunction with the GREAT spectrometer situated at the focal plane of the RITU. The yrast states are assigned to a strongly coupled rotational band based on a pi h(11/2) configuration. This structure exhibits large signature splitting at low spins that disappears after the paired band crossing because of the alignment of a pair of i(13/2) neutrons. This effect is ascribed to triaxial shape changes induced by the core-polarizing properties of the deformation-aligned h(11/2) proton and the rotation-aligned i(13/2) neutrons. Two additional strongly coupled band structures have been established and are discussed in terms of octupole-vibrational and two-quasiparticle excitations built on the yrast structure. The experimental results are compared with predictions from cranked-shell-model and total-Routhian-surface calculations.
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16.
  • Sohler, D, et al. (författare)
  • Maximally Aligned States in the Proton Drip Line Nucleus 106Sb
  • 2005
  • Ingår i: Nuclear Physics, Section A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 753:3-4, s. 251-262
  • Tidskriftsartikel (refereegranskat)abstract
    • High-spin states in Sb-106 have been investigated in the Fe-54(Ni-58, 1α 1p1n) reaction by in-beam γ-spectroscopic methods using the EUROBALL detector array equipped with charged particle and neutron detectors. On the basis of measured γγ-coincidence relations, angular distributions, and linear polarization ratios a significantly extended level scheme has been constructed up to spin and parity I-π = (19(-)) and E-x &SIM; 6.5 MeV. The experimental results are interpreted within the framework of the gdsh shell model using a realistic effective nucleon-nucleon interaction. Candidates for states with fully aligned angular momenta in the π(d(5/2), g(7/2))(1) v (d(5/2), g(7/2))(5) valence space are identified at 4338 and 5203 keV, as well as in the π(d(5/2), g(7/2))(1) V(d(5/2), g(7/2))(4)h(11/2)(1) space at 6087, 6573 and 6783 keV.
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