488 research outputs found
Quasiparticle resonance in decay spectrum of unbound nuclei near neutron drip-line
Background: The pairing correlation in weakly bound nuclei causes a mixing
among bound and unbound configurations. A remarkable consequence is emergence
of the quasiparticle resonance, which has been predicted with the coordinate
space Hartree-Fock-Bogoliubov (HFB) theory, but not yet observed
experimentally. Purpose: We discuss possible observation of quasiparticle
resonances in decay spectrum of unbound nuclei near the neutron drip-line. We
deal with an example of unbound nucleus C which disintegrates to
C and a neutron. Method: We describe a scattering state consisting of
C and a neutron in the framework of the HFB formalism. We assume that
a nucleon knockout reaction produces a doorway state of the decay, and we
evaluate the decay spectrum by taking an overlap of the doorway state and the
scattering state of . A numerical calculation was
performed with the Woods-Saxon potential and a density-dependent effective
pairing interaction. Results: We show that the quasiparticle resonance appears
as low-lying peaks in the decay spectrum of C. They originate from the
weakly bound single-neutron orbits and , but emerge as
unbound resonant quasiparticle states under the influence of the neutron
pairing correlation. The resonance energy and the width of the calculated
quasiparticle resonances are consistent with an experimental observation
whereas they are sensitive to the neutron pairing correlation. Conclusion: The
results suggest that nucleon knockout reactions populating the unbound nucleus
provide realistic opportunity of experimentally observing
the quasiparticle resonance and of disclosing the pairing correlation in
neutron-rich nuclei
Quark masses and CKM hierarchies from modular flavor symmetry
We propose models to explain the hierarchies of the quark masses and mixing
by utilizing the modular flavor symmetry. The hierarchy is
realized by the modulus stabilized at , where
the residual symmetry is approximately unbroken and the
Froggatt-Nielsen mechanism works. It is found that the quark hierarchies are
realized only in a few cases of quark representations. We study two models with
assigning the modular weights, so that the observed quark hierarchies are
explained in the cases of both small and large ratios of the top to bottom
Yukawa couplings. We also argue that hierarchies of the
coefficients can be explained by imposing another
modular symmetry.Comment: 13 pages, 3 tables; ver2 comments on CP violation adde
Fermion Hierarchies in Grand Unification from Modular Flavor Symmetry
We construct a model in which the hierarchies of the quark and lepton masses
and mixing are explained by the modular flavor symmetry. The
hierarchies are realized by the Froggatt-Nielsen-like mechanism due to the
residual symmetry, approximately unbroken at We
argue that the symmetry is the minimal possibility to
realize the up-type quark mass hierarchies, since the Yukawa matrix is
symmetric. We find a combination of the representations and modular weights and
then show numerical values of coefficients for the realistic
fermion hierarchies.Comment: 18 page
Carcinosarcoma of the Uterine Corpus with Alpha-Fetoprotein-Producing Hepatoid Adenocarcinoma: A Report of Two Cases
We report two cases of uterine carcinosarcoma associated with alpha-fetoprotein (AFP)-producing hepatoid adenocarcinoma. Samples were obtained from two women aged 63 and 82 years. Serum AFP levels of the two samples were 10,131 and 401 ng/ml, respectively. Histologically, in both cases the tumor cells were composed of hepatoid adenocarcinoma component and sarcoma component including rhabdomyosarcoma. Immunohistochemical analyses revealed that AFP was expressed in the cytoplasm of the carcinomatous component. After surgery, the patients received six courses of carboplatin/paclitaxel chemotherapy, and the serum levels of AFP decreased to normal range. The first patient is alive and well at the 2-year follow-up, while the second patient died of disease 1 year after initial operative treatment. This is, to our knowledge, the second report of carcinosarcoma of the uterine corpus with AFP-producing hepatoid adenocarcinoma, as proven by immunohistochemical analyses
子宮内膜症と関連する卵巣癌 : 明細胞腺癌と類内膜腺癌の発癌機序における相違点
The histogenesis of endometriosis and endometriosis-associated ovarian cancer is one of the most mysterious aspects of pathology. To better understand the histogenesis of endometriosis and endometriosis-associated ovarian cancer, we analyzed the possibility of a link of endometrium, ovarian surface epithelium, and a cortical inclusion cyst to ovarian endometriosis and endometriosis-associated ovarian cancer by immunohistochemistry using the epithelial membrane antigen (an epithelial marker), calretinin (a mesothelial marker), and hepatocyte nuclear factor (HNF)-1β (a clear cell carcinoma-specific transcription factor). During ovarian surface epithelium invagination, cortical inclusion cyst epithelial cells may, in some cases, undergo mesothelial–epithelial transition and subsequently differentiate into endometriosis. This case of endometriosis that has undergone Müllerian metaplasia arises from the HNF-1β-negative cells. The remaining endometriosis may develop from the late secretory and menstrual endometria, with HNF-1β-positive staining, by retrograde menstruation. Endometrioid adenocarcinoma and clear cell carcinoma arise from the HNF-1β-negative and HNF-1β-positive epithelial cells of endometriosis, respectively. It has been proposed that clear cell and endometrioid-type adenocarcinomas arise from distinct types of endometriosis with different cells of origin.博士(医学)・乙第1309号・平成25年3月15日©2012 International Society of Gynecological Pathologist
A Cardiac Rhabdomyoma in a Guinea Pig
A guinea pig (9-week-old) that had been placed in a control group for a
pharmacological test was found to have a single nodule on the surface of the
right ventricular wall. In a transverse section of the heart after fixation, a
whitish mass was found that extended from the subendocardium to the
subepicardium of the right ventricular wall. Histopathological examination
revealed a spongy network consisting of vacuolated spaces in the myocardium of
the right ventricle extending to the myocardium and subepicardium of the right
atrium. The vacuolated space was PAS-positive. Immunohistochemical examinations
revealed that the lesions contained striated fibers that were positive for
anti-desmin and anti-myoglobin. Electron micrographs revealed the lesions
resulting in affected striated muscle fibers and accumulations of many glycogen
granules. Based on the findings, the lesions were diagnosed as a cardiac
rhabdomyoma. This is the first report of application of immunohistochemical
examinations to diagnosis of cardiac rhabdomyoma in the guinea pig
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