365 research outputs found
Nuclear shape dependence of Gamow-Teller distributions in neutron-deficient Pb isotopes
We study Gamow-Teller strength distributions in the neutron-deficient even
isotopes (184-194)Pb in a search for signatures of deformation. The microscopic
formalism used is based on a deformed quasiparticle random phase approximation
(QRPA) approach, which involves a self-consistent quasiparticle deformed Skyrme
Hartree-Fock (HF) basis and residual spin-isospin forces in both the
particle-hole and particle-particle channels. By analyzing the sensitivity of
the Gamow-Teller strength distributions to the various ingredients in the
formalism, we conclude that the beta-decay of these isotopes could be a useful
tool to look for fingerprints of nuclear deformation.Comment: 20 pages, 11 figures. To be published in Physical Review
The beta-delayed neutron emission in 78Ni region
A systematic study of the total -decay half-lives and -delayed
neutron emission probabilities is performed. The -strength function is
treated within the self-consistent density-functional + continuum-QRPA
framework including the Gamow-Teller and first-forbidden transitions. The
experimental total -decay half-lives for the Ni isotopes with 76
are described satisfactorily. The half-lives predicted from =70 up to =86
reveal fairly regular -behaviour which results from simultaneous account for
the Gamow-Teller and first-forbidden transitions. For 28 nuclei, a
suppression of the delayed neutron emission probability is found when the
=50 neutron closed shell is crossed. The effect originates from the
high-energy first-forbidden transitions to the states outside the -window in the daughter nuclei.
PACS numbers: 23.40.Bw,21.60.Jz,25.30.Pt,26.30.+kComment: LaTeX, 13 pages, 5 figure
Solar Neutrinos from CNO Electron Capture
The neutrino flux from the sun is predicted to have a CNO-cycle contribution
as well as the known pp-chain component. Previously, only the fluxes from beta+
decays of 13N, 15O, and 17F have been calculated in detail. Another neutrino
component that has not been widely considered is electron capture on these
nuclei. We calculate the number of interactions in several solar neutrino
detectors due to neutrinos from electron capture on 13N, 15O, and 17F, within
the context of the Standard Solar Model. We also discuss possible non-standard
models where the CNO flux is increased.Comment: 4 pages, 1 figure, submitted to Phys. Rev. C; v2 has minor changes
including integration over solar volume and addition of missing reference to
previous continuum electron capture calculation; v3 has minor changes
including addition of references and the correction of a small (about 1%)
numerical error in the table
beta-decay in neutron-deficient Hg, Pb, and Po isotopes
The effect of nuclear deformation on the energy distributions of the
Gamow-Teller strength is studied in neutron-deficient Hg, Pb, and Po even
isotopes. The theoretical framework is based on a self-consistent deformed
Skyrme Hartree-Fock mean field with pairing correlations between like nucleons
in BCS approximation and residual spin-isospin interactions treated in the
proton-neutron quasiparticle random phase approximation. After a systematic
study of the Gamow-Teller strength distributions in the low excitation energy
region, relevant for beta-decay, we have identified the best candidates to look
for deformation signatures in their beta-decay patterns. beta+ half-lives and
total Gamow-Teller strengths B(GT+) and B(GT-) are analyzed as well.Comment: 18 pages, 7 figures, to appear in Phys. Rev.
âThey Called Them Communists ThenââŚâWhat D'You Call âEm Now?ââŚâInsurgents?â. Narratives of British Military Expatriates in the Context of the New Imperialism
This paper addresses the question of the extent to which the colonial past provides material for contemporary actors' understanding of difference. The research from which the paper is drawn involved interview and ethnographic work in three largely white working-class estates in an English provincial city. For this paper we focus on ten life-history interviews with older participants who had spent some time abroad in the British military. Our analysis adopts a postcolonial framework because research participants' current constructions of an amorphous 'Other' (labelled variously as black people, immigrants, foreigners, asylum-seekers or Muslims) reveal strong continuities with discourses deployed by the same individuals to narrate their past experiences of living and working as either military expatriates or spouses during British colonial rule. Theoretically, the paper engages with the work of Frantz Fanon and Edward Said. In keeping with a postcolonial approach, we work against essentialised notions of identity based on 'race' or class. Although we establish continuity between white working-class military emigration in the past and contemporary racialised discourses, we argue that the latter are not class-specific, being as much the creations of the middle-class media and political elite
Deformation of the N=Z nucleus 76Sr using beta-decay studies
A novel method of deducing the deformation of the N=Z nucleus 76Sr is
presented. It is based on the comparison of the experimental Gamow-Teller
strength distribution B(GT) from its beta decay with the results of QRPA
calculations. This method confirms previous indications of the strong prolate
deformation of this nucleus in a totally independent way. The measurement has
been carried out with a large Total Absorption gamma Spectrometer, "Lucrecia",
newly installed at CERN-ISOLDE.Comment: Accepted in Phys. Rev. Letter
Beta decay of 115-In to the first excited level of 115-Sn: Potential outcome for neutrino mass
Recent observation of beta decay of 115-In to the first excited level of
115-Sn with an extremely low Q_beta value (Q_beta ~ 1 keV) could be used to set
a limit on neutrino mass. To give restriction potentially competitive with
those extracted from experiments with 3-H (~2 eV) and 187-Re (~15 eV), atomic
mass difference between 115-In and 115-Sn and energy of the first 115-Sn level
should be remeasured with higher accuracy (possibly of the order of ~1 eV).Comment: 9 pages, 3 figures; talk at the NANP'05 Conferenc
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The Psy-Security-Curriculum ensemble: British Values curriculum policy in English schools
Framed as being in response to terrorist attacks and concerns about religious bias in some English schools, âBritish Valuesâ (BV) curriculum policy forms part of the British Governmentâs Counter-Terrorism and Security Act, 2015. This includes a Duty on teachers in England to actively promote British Values to deter students from radicalisation. This paper, first, traces the history of Britishness in the curriculum to reveal a prevalence of nationalistic, colonial values. Next, an ensemble of recent policies and speeches focusing on British Values is analysed, using a psycho-political approach informed by anti-colonial scholarship. Finally, we interrogate two key critiques of the British Values curriculum discourse: the universality of British Values globally, and concerns over the securitisation of education. Findings indicate that the constitution of white British supremacist subjectivities operate through curriculum as a defence mechanism against perceived threats to white privilege, by normalising a racialised state-controlled social order. The focus is on âBritishâ values, but the analytic framework and findings have wider global significance
Positron-neutrino correlation in the 0^+ \to 0^+ decay of ^{32}Ar
The positron-neutrino correlation in the decay of
Ar was measured at ISOLDE by analyzing the effect of lepton recoil on
the shape of the narrow proton group following the superallowed decay. Our
result is consistent with the Standard Model prediction. For vanishing Fierz
interference we find , which yields improved
constraints on scalar weak interactions
Prevalence and Predictors of Urinary Tract Infection and Severe Malaria Among Febrile Children Attending Makongoro Health Centre in Mwanza City, North-Western Tanzania.
In malaria endemic areas, fever has been used as an entry point for presumptive treatment of malaria. At present, the decrease in malaria transmission in Africa implies an increase in febrile illnesses related to other causes among underfives. Moreover, it is estimated that more than half of the children presenting with fever to public clinics in Africa do not have a malaria infection. Thus, for a better management of all febrile illnesses among under-fives, it becomes relevant to understand the underlying aetiology of the illness. The present study was conducted to determine the relative prevalence and predictors of P. falciparum malaria, urinary tract infections and bacteremia among under-fives presenting with a febrile illness at the Makongoro Primary Health Centre, North-Western Tanzania. From February to June 2011, a cross-sectional analytical survey was conducted among febrile children less than five years of age. Demographic and clinical data were collected using a standardized pre-tested questionnaire. Blood and urine culture was done, followed by the identification of isolates using in-house biochemical methods. Susceptibility patterns to commonly used antibiotics were investigated using the disc diffusion method. Giemsa stained thin and thick blood smears were examined for any malaria parasites stages. A total of 231 febrile under-fives were enrolled in the study. Of all the children, 20.3% (47/231, 95%CI, 15.10-25.48), 9.5% (22/231, 95%CI, 5.72-13.28) and 7.4% (17/231, 95%CI, 4.00-10.8) had urinary tract infections, P. falciparum malaria and bacteremia respectively. In general, 11.5% (10/87, 95%CI, 8.10-14.90) of the children had two infections and only one child had all three infections. Predictors of urinary tract infections (UTI) were dysuria (OR = 12.51, 95% CI, 4.28-36.57, P < 0.001) and body temperature (40-41 C) (OR = 12.54, 95% CI, 4.28-36.73, P < 0.001). Predictors of P. falciparum severe malaria were pallor (OR = 4.66 95%CI, 1.21-17.8, P = 0.025) and convulsion (OR = 102, 95% CI, 10-996, P = 0.001). Escherichia coli were the common gram negative isolates from urine (72.3%, 95% CI, 66.50-78.10) and blood (40%, 95%CI, and 33.70-46.30). Escherichia coli from urine were 100% resistant to ampicillin, 97% resistant to co-trimoxazole, 85% resistant to augmentin and 32.4% resistant to gentamicin; and they were 100%, 91.2% and 73.5% sensitive to meropenem, ciprofloxacin and ceftriaxone respectively. Urinary tract infection caused by multi drug resistant Escherichia coli was the common cause of febrile illness in our setting. Improvement of malaria diagnosis and its differential diagnosis from other causes of febrile illnesses may provide effective management of febrile illnesses among children in Tanzania
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