484 research outputs found

    No-Core shell model for A = 47 and A = 49

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    We apply an {\it ab-initio} approach to the nuclear structure of odd-mass nuclei straddling 48Ca^{48}Ca. Starting with the NN interaction, that fits two-body scattering and bound state data we evaluate the nuclear properties of A=47A = 47 and A=49A = 49 nuclei in a no-core approach. Due to model space limitations and the absence of 3-body interactions, we incorporate phenomenological terms determined by fits to A=48A = 48 nuclei in a previous effort. Our modified Hamiltonian produces reasonable spectra for these odd mass nuclei. In addition to the differences in single-particle basis states, the absence of a single-particle Hamiltonian in our no-core approach obscures direct comparisons with valence effective NN interactions. Nevertheless, we compare the fp-shell matrix elements of our initial and modified Hamiltonians in the harmonic oscillator basis with a recent model fp-shell interaction, the GXPF1 interaction of Honma, Otsuka, Brown and Mizusaki. Notable differences emerge from these comparisons. In particular, our diagonal two-body T=0T = 0 matrix elements are, on average, about 800-900keV more attractive. Furthermore, while our initial and modified NN Hamiltonian fp-shell matrix elements are strongly correlated, there is much less correlation with the GXPF1 matrix elements.Comment: 17 pages including 14 figure

    What spelling errors can tell us about the development of processes involved in children’s spelling

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    Introduction: Spelling is an essential foundation for reading and writing. However, many children leave school with spelling difficulties. By understanding the processes children use when they spell, we can intervene with appropriate instruction tailored to their needs. Methods: Our study aimed to identify key processes (lexical-semantic and phonological) by using a spelling assessment that distinguishes different printed letter strings/word types (regular and irregular words, and pseudowords). Misspellings in the test from 641 pupils in Reception Year to Year 6 were scored using alternatives to binary correct versus incorrect scoring systems. The measures looked at phonological plausibility, phoneme representations and letter distance. These have been used successfully in the past but not with a spelling test that distinguishes irregularly spelled words from regular words and pseudowords. Results: The findings suggest that children in primary school rely on both lexical-semantic and phonological processes to spell all types of letter string, but this varies depending on the level of spelling experience (younger Foundation/Key stage 1 and older Key stage 2). Although children in younger year groups seemed to rely more on phonics, based on the strongest correlation coefficients for all word types, with further spelling experience, lexical processes seemed to be more evident, depending on the type of word examined. Discussion: The findings have implications for the way we teach and assess spelling and could prove to be valuable for educators

    Unveiling the intruder deformed 02+^+_2 state in 34^{34}Si

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    The 02+^+_2 state in 34^{34}Si has been populated at the {\sc Ganil/Lise3} facility through the β\beta-decay of a newly discovered 1+^+ isomer in 34^{34}Al of 26(1) ms half-life. The simultaneous detection of e+ee^+e^- pairs allowed the determination of the excitation energy E(02+^+_2)=2719(3) keV and the half-life T1/2_{1/2}=19.4(7) ns, from which an electric monopole strength of ρ2\rho^2(E0)=13.0(0.9)×103\times10^{-3} was deduced. The 21+^+_1 state is observed to decay both to the 01+^+_1 ground state and to the newly observed 02+^+_2 state (via a 607(2) keV transition) with a ratio R(21+^+_101+/21+\rightarrow0^+_1/2^+_102+\rightarrow0^+_2)=1380(717). Gathering all information, a weak mixing with the 01+^+_1 and a large deformation parameter of β\beta=0.29(4) are found for the 02+^+_2 state, in good agreement with shell model calculations using a new {\sc sdpf-u-mix} interaction allowing \textit{np-nh} excitations across the N=20 shell gap.Comment: 5 pages, 3 figures, accepted for publication in Physical Review Letter

    Characterizations of hemirings by their hh-ideals

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    In this paper we characterize hemirings in which all hh-ideals or all fuzzy hh-ideals are idempotent. It is proved, among other results, that every hh-ideal of a hemiring RR is idempotent if and only if the lattice of fuzzy hh-ideals of RR is distributive under the sum and hh-intrinsic product of fuzzy hh-ideals or, equivalently, if and only if each fuzzy hh-ideal of RR is intersection of those prime fuzzy hh-ideals of RR which contain it. We also define two types of prime fuzzy hh-ideals of RR and prove that, a non-constant hh-ideal of RR is prime in the second sense if and only if each of its proper level set is a prime hh-ideal of RR

    Comparison of Transfer-to-Continuum and Eikonal Models of Projectile Fragmentation Reactions

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    Spectroscopic properties of nuclei are accessible with projectile fragmentation reactions, but approximations made in the reaction theory can limit the accuracy of the determinations. We examine here two models that have rather different approximations for the nucleon wave function, the target interaction, and the treatment of the finite duration of the reaction. The nucleon-target interaction is treated differently in the eikonal and the transfer-to-continuum model, but the differences are more significant for light targets. We propose a new parameterization with that in mind. We also propose a new formula to calculate the amplitude that combines the better treatment of the wave function in the eikonal model with the better treatment of the target interaction in the transfer-to-continuum model.Comment: 21 pages, latex file including 3 tables. 5 figures. Submitted to Phys. Rev.

    Surgical treatment of pancreatic fistula after acute pancreatitis

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    Clinica I Chirurgie, Spitalul “Sf.Spiridon”, Departamentul de Chirurgie, Universitatea de Medicină şi Farmacie “Gr.T.Popa”, Iași, România, Al XII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova cu participare internațională 23-25 septembrie 2015Introducere: Fistula pancreatică este o complicație rară care apare în evoluția pancreatitei acute. Această complicație agravează evoluția bolii și este dificil de tratat, mai ales dacă are un debit important. Posibilitățile de tratament și momentul optim al intervenției chirurgicale rămân discutabile. Prezentare de caz: Pacient de 51 ani, sex masculin, consumător de alcool, se internează pentru dureri în etajul abdominal superior, grețuri, vărsături și meteorism. Se stabilește diagnosticul de pancreatită acută și se inițiază tratament conservator. La două săptămâni de la debut dezvoltă un abces subhepatic pentru care se intervine chirurgical. Începînd din ziua a 7-a postoperator pe tubul de dren subhepatic apare suc pancreatic cu un debit de 400-500 ml/zi. Explorările imagistice efectuate confirmă diagnosticul de fistulă pancreatică. După maturarea traectului fistulos se intervine chirurgical și se practică fistulojejunoanastomoză pe ansă în Y a la Roux. Evoluția postoperatorie a fost favorabilă. Pacientul se simte bine și nu are nici o acuză la 6 luni postoperator. Concluzie: Fistulo-jejunoanastomoza pe ansă Roux cu un traiect fistulos maturat este o soluție viabilă de tratament al fistulei pancreatice apărute în pancreatita acută.Introduction: Pancreatic fistula is a rare complication of acute pancreatitis, which seriously worsens the evolution and is a treatment challenge, especially when the output is high. The treatment options and timing are debatable. Case report: Male patient, 51, with a history of alcohol abuse, is admitted with pain in the upper abdomen, nausea, vomiting, abdominal distension, high amylasemia and lipasemia and the diagnosis of acute pancreatitis is established. After 2 weeks of treatment, a subhepatic abscess is surgically drained. Starting on the 7th postoperative day the subhepatic drainage tube produces 400-500 ml daily. Imaging explorations show a pancreatic fistula. After a delay for fistula maturation, Roux-en-Y fistula-jejunal anastomosis has been performed. Postoperative period was uneventful, with asymptomatic patient 6 months later. Conclusion: Roux-en-Y fistula-jejunal anastomosis of a mature pancreatic fistula is a valid approach in the management of high output pancreatic fistula after acute pancreatitis

    Breakup of loosely bound nuclei as indirect method in nuclear astrophysics: 8B, 9C, 23Al

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    We discuss the use of one-nucleon breakup reactions of loosely bound nuclei at intermediate energies as an indirect method in nuclear astrophysics. These are peripheral processes, therefore we can extract asymptotic normalization coefficients (ANC) from which reaction rates of astrophysical interest can be inferred. To show the usefulness of the method, three different cases are discussed. In the first, existing experimental data for the breakup of 8B at energies from 30 to 1000 MeV/u and of 9C at 285 MeV/u on light through heavy targets are analyzed. Glauber model calculations in the eikonal approximation and in the optical limit using different effective interactions give consistent, though slightly different results, showing the limits of the precision of the method. The results lead to the astrophysical factor S_17(0)=18.7+/-1.9 eVb for the key reaction for solar neutrino production 7Be(p,\gamma)8B. It is consistent with the values from other indirect methods and most direct measurements, but one. Breakup reactions can be measured with radioactive beams as weak as a few particles per second, and therefore can be used for cases where no direct measurements or other indirect methods for nuclear astrophysics can be applied. We discuss a proposed use of the breakup of the proton drip line nucleus 23Al to obtain spectroscopic information and the stellar reaction rate for 22Mg(p,\gamma)23Al.Comment: 6 pages, 4 figures. Presented at the conference "Nuclear Physics for Astrophysics 2", Debrecen, Hungary, May 2005. Prepared for the Proceeding

    New pathway to bypass the 15O waiting point

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    We propose the sequential reaction process 15^{15}O(pp,γ)(β+\gamma)(\beta^{+})16^{16}O as a new pathway to bypass of the 15^{15}O waiting point. This exotic reaction is found to have a surprisingly high cross section, approximately 1010^{10} times higher than the 15^{15}O(pp,β+\beta^{+})16^{16}O. These cross sections were calculated after precise measurements of energies and widths of the proton-unbound 16^{16}F low lying states, obtained using the H(15^{15}O,p)15^{15}O reaction. The large (p,γ)(β+)(p,\gamma)(\beta^{+}) cross section can be understood to arise from the more efficient feeding of the low energy wing of the ground state resonance by the gamma decay. The implications of the new reaction in novae explosions and X-ray bursts are discussed.Comment: submitte

    Spectroscopy of 26^{26}F

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    The structure of the weakly-bound     926^{26}_{\;\;9}F17_{17} odd-odd nucleus, produced from 27,28^{27,28}Na nuclei, has been investigated at GANIL by means of the in-beam γ\gamma-ray spectroscopy technique. A single γ\gamma-line is observed at 657(7) keV in 926^{26}_{9}F which has been ascribed to the decay of the excited J=2+2^+ state to the J=1+^+ ground state. The possible presence of intruder negative parity states in 26^{26}F is also discussed.Comment: 3 pages, 1 figure, accepted for publication in Physical Review
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