737 research outputs found
The no-core shell model with general radial bases
Calculations in the ab initio no-core shell model (NCSM) have conventionally
been carried out using the harmonic-oscillator many-body basis. However, the
rapid falloff (Gaussian asymptotics) of the oscillator functions at large
radius makes them poorly suited for the description of the asymptotic
properties of the nuclear wavefunction. We establish the foundations for
carrying out no-core configuration interaction (NCCI) calculations using a
basis built from general radial functions and discuss some of the
considerations which enter into using such a basis. In particular, we consider
the Coulomb-Sturmian basis, which provides a complete set of functions with a
realistic (exponential) radial falloff.Comment: 7 pages, 3 figures; presented at Horizons on Innovative Theories,
Experiments, and Supercomputing in Nuclear Physics 2012, New Orleans,
Louisiana, June 4-7, 2012; submitted to J. Phys. Conf. Se
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Oxidative stress specifically downregulates survivin to promote breast tumour formation.
BackgroundBreast cancer, a heterogeneous disease has been broadly classified into oestrogen receptor positive (ER+) or oestrogen receptor negative (ER-) tumour types. Each of these tumours is dependent on specific signalling pathways for their progression. While high levels of survivin, an anti-apoptotic protein, increases aggressive behaviour in ER- breast tumours, oxidative stress (OS) promotes the progression of ER+ breast tumours. Mechanisms and molecular targets by which OS promotes tumourigenesis remain poorly understood.ResultsDETA-NONOate, a nitric oxide (NO)-donor induces OS in breast cancer cell lines by early re-localisation and downregulation of cellular survivin. Using in vivo models of HMLE(HRAS) xenografts and E2-induced breast tumours in ACI rats, we demonstrate that high OS downregulates survivin during initiation of tumourigenesis. Overexpression of survivin in HMLE(HRAS) cells led to a significant delay in tumour initiation and tumour volume in nude mice. This inverse relationship between survivin and OS was also observed in ER+ human breast tumours. We also demonstrate an upregulation of NADPH oxidase-1 (NOX1) and its activating protein p67, which are novel markers of OS in E2-induced tumours in ACI rats and as well as in ER+ human breast tumours.ConclusionOur data, therefore, suggest that downregulation of survivin could be an important early event by which OS initiates breast tumour formation
Heavy Baryons in a Quark Model
A quark model is applied to the spectrum of baryons containing heavy quarks.
The model gives masses for the known heavy baryons that are in agreement with
experiment, but for the doubly-charmed baryon Cascade_{cc}, the model
prediction is too heavy. Mixing between the Cascade_Q and Cascade_Q^\prime
states is examined and is found to be small for the lowest lying states. In
contrast with this, mixing between the Cascade_{bc} and Cascade_{bc}^\prime
states is found to be large, and the implication of this mixing for properties
of these states is briefly discussed. We also examine heavy-quark spin-symmetry
multiplets, and find that many states in the model can be placed in such
multiplets. We compare our predictions with those of a number of other authors.Comment: Version published in International Journal of Modern Physics
Semileptonic Decays of Heavy Lambda Baryons in a Quark Model
The semileptonic decays of Lambda_c and Lambda_b are treated in the framework
of a constituent quark model. Both nonrelativistic and semirelativistic
Hamiltonians are used to obtain the baryon wave functions from a fit to the
spectra, and the wave functions are expanded in both the harmonic oscillator
and Sturmian bases. The latter basis leads to form factors in which the
kinematic dependence on q^2 is in the form of multipoles, and the resulting
form factors fall faster as a function of q^2 in the available kinematic
ranges. As a result, decay rates obtained in the two models using the Sturmian
basis are significantly smaller than those obtained using the harmonic
oscillator basis. In the case of the Lambda_c, decay rates calculated using the
Sturmian basis are closer to the experimentally reported rates. However, we
find a semileptonic branching fraction for the Lambda_c to decay to excited
Lambda* states of 11% to 19%, in contradiction with what is assumed in
available experimental analyses. Our prediction for the Lambda_b semileptonic
decays is that decays to the ground state Lambda_c provide a little less than
70% of the total semileptonic decay rate. For the decays Lambda_b to Lambda_c,
the analytic form factors we obtain satisfy the relations expected from
heavy-quark effective theory at the non-recoil point, at leading and
next-to-leading orders in the heavy-quark expansion. In addition, some features
of the heavy-quark limit are shown to naturally persist as the mass of the
heavy quark in the daughter baryon is decreased.Comment: 51 pages, 8 figures, submitted to Physical Review
The Role of in Two-pion Exchange Three-nucleon Potential
In this paper we have studied the two-pion exchange three-nucleon potential
using an approximate chiral symmetry of the
strong interaction. The off-shell pion-nucleon scattering amplitudes obtained
from the Weinberg Lagangian are supplemented with contributions from the
well-known -term and the exchange. It is the role of the
-resonance in , which we have investigated in detail in the
framework of the Lagrangian field theory. The -contribution is quite
appreciable and, more significantly, it is dependent on a parameter Z which is
arbitrary but has the empirical bounds . We find that the
-contribution to the important parameters of the depends
on the choice of a value for Z, although the correction to the binding energy
of triton is not expected to be very sensitive to the variation of Z within its
bounds.Comment: 14 pages, LaTe
Production and quality assessment of fish pickles from mola (Amblypharyngodon mola) fish
Fish pickles (with olive and tamarind) were prepared from mola fish (Amblypharyngodon mola) and their nutritional and food quality were assessed. The quality of the pickle prepared with olive was excellent and the pickle prepared with tamarind was found good. Moisture content of the two pickle products were 43.85% (with tamarind) and 50.89% (with olive). The protein and lipid contents of tamarind added pickle were 19.13 and 35.64% respectively; pickle with olive contained less protein (13.16%) compared to tamarind added mola pickle. Lipid contents were almost same in both cases. Ash content of two pickles was also found similar (1.00%). The quality of mola pickles stored either in cool condition (4°C) with vinegar or at room temperature with Na-benzoate were found good for consumption up to 90 days of storage. All of the fish pickles preserved under different condition were found in acceptable condition up to 240 days storage and pickle with vinegar stored at 4°C was found good for consumption at the end of 240 days
Clinico-histopathological correlation of abdominal hysterectomy
 Background: Hysterectomy is the most common gynaecological procedure performed. Abdominal hysterectomy remains the most common approach though recently there has been preference towards laparoscopic hysterectomy. It is still considered as the treatment of choice for benign lesion such as leiomyoma, adenomyosis, extensive pelvic infection or adhesions, dysfunctional uterine bleeding and obstetric complications. Objectives were to correlate the indications of abdominal hysterectomy to histopathological findings thus, determining histologically confirmed preoperative clinical diagnosis.Methods: This study was conducted at the department of obstetrics and gynaecology, Bangabandhu Sheikh Mujib medical university, Dhaka from August 2010 to January 2011. This is a descriptive analysis of the patients who had undergone abdominal hysterectomy during the study period.Results: One hundred patients undergoing abdominal hysterectomy were studied. Data were recorded on structured proforma, including demographic characteristics, clinical features and indications of the procedure. In. our study, it was observed that the most common clinical diagnosis was leiomyoma of uterus 52 (52%). Other clinical diagnosis was DUB in 30 cases (30%), adenomyosis in 7 cases (7%), endometriosis in 6 cases (6%). Pelvic inflammatory disease in 3 cases (3%), endometrial polyp (2%). Abdominal hysterectomy was the single approach done in these cases. Clinical, radiological as well as histopathology report correlated uterine leiomyoma very well and it was about 94.23%, while DUB was a disease of exclusion. In 53 cases combined pathology was found.Conclusions: Hysterectomy is currently the most widely performed major operation in gynaecology and histopathology is mandatory for ensuring diagnosis and management. With the improvement in the different organ preserving options, hysterectomy in benign disease should only be opted when all the other conservative options failure.
Tetranuclear Group 7/8 Mixed-Metal and Open Trinuclear Group 7 Metal Carbonyl Clusters Bearing Bridging 2-mercapto-1-methylimidazole Ligands
The reactivity of group 7 metal dinuclear carbonyl complexes [M2(CO)6(μ-SN2C4H5)2] (1, M = Re; 2, M = Mn) toward group 8 metal trinuclear carbonyl clusters were examined. Reactions of 1 and 2 with [Os3(CO)10(NCMe)2] in refluxing benzene furnished the tetranuclear mixed-metal clusters [Os3Re(CO)13(μ3-SN2C4H5)] (3) and [Os3Mn(CO)13(μ3-SN2C4H5)] (4), respectively. Similar treatment of 1 and 2 with Ru3(CO)12 yielded the ruthenium analogs [Ru3Re(CO)13(μ3-SN2C4H5)] (5), and [Ru3Mn(CO)13(μ3-SN2C4H5)] (6), but in the case of 2 a secondary product [Mn3(CO)10(μ-Cl)(μ3-SN2C4H5)2] (7) was also formed. Compounds 3–6 have a butterfly core of four metal atoms with the M (Mn or Re) at a wingtip of the butterfly and containing a noncrystallographic mirror plane of symmetry. This result provides a potential method for the synthesis of a series of new group 7/8 mixed metal complexes containing a bifunctional heterocyclic ligand. Compound 7 is a unique example of a 54-electron trimanganese complex having bridging 2-mercapto-1-methylimidazolate and chloride ligands. Interestingly, the reaction of 1 with Fe3(CO)12 at 70–75 °C furnished the tri- and dirhenium complexes [Re3(CO)10(μ-H)(μ3-SN2C4H5)2] (8) and [Re2(CO)6(N2C4H5)(μ-SN2C4H5)2] (9), respectively instead of the expected formation of the mixed-metal clusters. The former is an interesting example of a 52-electron trirhenium-hydridic complex containing bridging 2-mercapto-1-methylimidazolate ligand, while the latter can be viewed as a 1-methylimidazole adduct of 1. No mixed Fe–Re complexes were produced in this reaction. The molecular structures of the new compounds 3–5 and 7–9 were established by single-crystal X-ray diffraction analyses and the DFT studies of compounds 5, 7 and 8 are reported
Is famine exposure during developmental life in rural Bangladesh associated with a metabolic and epigenetic signature in young adulthood? A historical cohort study
Objectives Famine exposure in utero can ‘programme’ an individual towards type 2 diabetes and obesity in later life. We sought to identify, (1) whether Bangladeshis exposed to famine during developmental life are programmed towards diabetes and obesity, (2) whether this programming was specific to gestational or postnatal exposure windows and (3) whether epigenetic differences were associated with famine exposure.
Design A historical cohort study was performed as part of a wider cross-sectional survey. Exposure to famine was defined through birth date and historical records and participants were selected according to: (A) exposure to famine in postnatal life, (B) exposure to famine during gestation and (C) unexposed.
Setting Matlab, a rural area in the Chittagong division of Bangladesh.
Participants Young adult men and women (n=190) recruited to a historical cohort study with a randomised subsample included in an epigenetic study (n=143).
Outcome measures Primary outcome measures of weight, body mass index and oral glucose tolerance tests (0 and 120 min glucose). Secondary outcome measures included DNA methylation using genome-wide and targeted analysis of metastable epialleles sensitive to maternal nutrition.
Results More young adults exposed to famine in gestation were underweight than those postnatally exposed or unexposed. In contrast, more young adults exposed to famine postnatally were overweight compared to those gestationally exposed or unexposed. Underweight adults exposed to famine in gestation in utero were hyperglycaemic following a glucose tolerance test, and those exposed postnatally had elevated fasting glucose, compared to those unexposed. Significant differences in DNA methylation at seven metastable epialleles (VTRNA2-1, PAX8, PRDM-9, near ZFP57, near BOLA, EXD3) known to vary with gestational famine exposure were identified.
Conclusions Famine exposure in developmental life programmed Bangladeshi offspring towards diabetes and obesity in adulthood but gestational and postnatal windows of exposure had variable effects on phenotype. DNA methylation differences were replicated at previously identified metastable epialleles sensitive to periconceptual famine exposure
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