448 research outputs found
Coupled-channels analyses for large-angle quasi-elastic scattering in massive systems
We discuss in detail the coupled-channels approach for the large-angle
quasi-elastic scattering in massive systems, where many degrees of freedom may
be involved in the reaction. We especially investigate the effects of single,
double and triple phonon excitations on the quasi-elastic scattering for
Ti,Cr,Fe,Ni and ZnPb systems, for
which the experimental cross sections have been measured recently. We show that
the present coupled-channels calculations well account for the overall width of
the experimental barrier distribution for these systems. In particular, it is
shown that the calculations taking into account single quadrupole phonon
excitations in Ti and triple octupole phonon excitations in Pb
reasonably well reproduce the experimental quasi-elastic cross section and
barrier distribution for the TiPb reaction. On the other hand,
Cr,Fe,Ni and ZnPb systems seem to require
the double quadrupole phonon excitations in the projectiles in order to
reproduce the experimental data.Comment: 11 pages, 6 figure
Cyclophosphamide eliminates suppressor T cells in age-associated central regulation of delayed hypersensitivity in mice.
Spin-parity assignments in ^<15>C^* by a new method : β-delayed spectroscopy for a spin-polarized nucleus
β-delayed neutron and γ-ray spectroscopy of ^<17>C utilizing spin-polarized ^<17>B
Excited states in ^C were investigated through the measurement of β -delayed neutrons and γ rays emitted in the β decay of ^B. In the measurement, three negative-parity states and two inconclusive states were identified in ^C above the neutron threshold energy, and seven γ lines were identified in a β -delayed multiple neutron emission of the ^Bβ decay. From these transitions, the β-decay scheme of ^B was determined. In particular, a de-excitation 1766-keVγ line from the first excited state of ^C was observed in coincidence with the emitted β-delayed neutrons, and this changes the previously reported β-decay scheme of ^B and level structure of ^C. In the present work, the β-NMR technique is combined with the β-delayed particle measurements using a fragmentation-induced spin-polarized ^B beam. This new scheme allows us to determine the spin parity of β-decay feeding excited states based on the difference in the discrete β-decay asymmetry parameters, provided the states are connected through the Gamow-Teller transition. In this work, I^π=1/2^−, 3/2^−, and (5/2^−) are assigned to the observed states at E_x = 2.71(2), 3.93(2), and 4.05(2) MeV in ^C, respectively
Recent experimental results in sub- and near-barrier heavy ion fusion reactions
Recent advances obtained in the field of near and sub-barrier heavy-ion
fusion reactions are reviewed. Emphasis is given to the results obtained in the
last decade, and focus will be mainly on the experimental work performed
concerning the influence of transfer channels on fusion cross sections and the
hindrance phenomenon far below the barrier. Indeed, early data of sub-barrier
fusion taught us that cross sections may strongly depend on the low-energy
collective modes of the colliding nuclei, and, possibly, on couplings to
transfer channels. The coupled-channels (CC) model has been quite successful in
the interpretation of the experimental evidences. Fusion barrier distributions
often yield the fingerprint of the relevant coupled channels. Recent results
obtained by using radioactive beams are reported. At deep sub-barrier energies,
the slope of the excitation function in a semi-logarithmic plot keeps
increasing in many cases and standard CC calculations over-predict the cross
sections. This was named a hindrance phenomenon, and its physical origin is
still a matter of debate. Recent theoretical developments suggest that this
effect, at least partially, may be a consequence of the Pauli exclusion
principle. The hindrance may have far-reaching consequences in astrophysics
where fusion of light systems determines stellar evolution during the carbon
and oxygen burning stages, and yields important information for exotic
reactions that take place in the inner crust of accreting neutron stars.Comment: 40 pages, 63 figures, review paper accepted for EPJ
Unilateral aplasia of both cruciate ligaments
Aplasia of both cruciate ligaments is a rare congenital disorder. A 28-year-old male presented with pain and the feeling of instability of his right knee after trauma. The provided MRI and previous arthroscopy reports did not indicate any abnormalities except cruciate ligament tears. He was referred to us for reconstruction of both cruciate ligaments. The patient again underwent arthroscopy which revealed a hypoplasia of the medial trochlea and an extremely narrow intercondylar notch. The tibia revealed a missing anterior cruciate ligament (ACL) footprint and a single bump with a complete coverage with articular cartilage. There was no room for an ACL graft. A posterior cruciate ligament could not be identified. The procedure was ended since a ligament reconstruction did not appear reasonable. A significant notch plasty if not a partial resection of the condyles would have been necessary to implant a ligament graft. It is most likely that this would not lead to good knee stability. If the surgeon would have retrieved the contralateral hamstrings at the beginning of the planned ligament reconstruction a significant damage would have occurred to the patient. Even in seemingly clear diagnostic findings the arthroscopic surgeon should take this rare abdnormality into consideration and be familiar with the respective radiological findings. We refer the abnormal finding of only one tibial spine to as the "dromedar-sign" as opposed to the two (medial and a lateral) tibial spines in a normal knee. This may be used as a hint for aplasia of the cruciate ligaments
Identification and genotyping of bacteria from paired vaginal and rectal samples from pregnant women indicates similarity between vaginal and rectal microflora
Background: The vaginal microflora is important for maintaining vaginal health and preventing infections of the reproductive tract. The rectum has been suggested as the major source for the colonisation of the vaginal econiche.
Methods: To establish whether the rectum can serve as a possible bacterial reservoir for colonisation of the vaginal econiche, we cultured vaginal and rectal specimens from pregnant women at 35-37 weeks of gestation, identified the isolates to the species level with tRNA intergenic length polymorphism analysis (tDNA-PCR) and genotyped the isolates for those subjects from which the same species was isolated simultaneously vaginally and rectally, by RAPD-analysis.
One vaginal and one rectal swab were collected from a total of each of 132 pregnant women at 35-37 weeks of gestation. Swabs were cultured on Columbia CNA agar and MRS agar. For each subject 4 colonies were selected for each of both sites, i.e. 8 colonies in total.
Results: Among the 844 isolates that could be identified by tDNA-PCR, a total of 63 bacterial species were present, 9 (14%) only vaginally, 26 (41%) only rectally, and 28 (44%) in both vagina and rectum. A total of 121 (91.6%) of 132 vaginal samples and 51 (38.6%) of 132 rectal samples were positive for lactobacilli. L. crispatus was the most frequently isolated Lactobacillus species from the vagina (40% of the subjects were positive), followed by L. jensenii (32%), L. gasseri (30%) and L. iners (11%). L. gasseri was the most frequently isolated Lactobacillus species from the rectum (15%), followed by L. jensenii (12%), L. crispatus (11%) and L. iners (2%).
A total of 47 pregnant women carried the same species vaginally and rectally. This resulted in 50 vaginal/rectal pairs of the same species, for a total of eight different species. For 34 of the 50 species pairs (68%), isolates with the same genotype were present vaginally and rectally and a high level of genotypic diversity within species per subject was also established.
Conclusion: It can be concluded that there is a certain degree of correspondence between the vaginal and rectal microflora, not only with regard to species composition but also with regard to strain identity between vaginal and rectal isolates.
These results support the hypothesis that the rectal microflora serves as a reservoir for colonisation of the vaginal econiche
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