Ab initio calculation of the 4He(e,e'd)d reaction

The two-body knock-out reaction 4He(e,e'd)d is calculated at various momentum transfers. The full four-nucleon dynamics is taken into account microscopically both in the initial and the final states. As NN interaction the central MT-I/III potential is used. The calculation shows a strong reduction of the coincidence cross section due to the final state interaction. Nonetheless the theoretical results exhibit a considerable overestimation of the experimental cross section at lower momentum transfer. Comparisons with other, less complete, calculations suggest that consideration of a more realistic ground state might not be sufficient for a good agreement with experiment, rather a more realistic final state interaction could play an essential role.Comment: 14 pages, 5 figure

On the ill-posed character of the Lorentz integral transform

An exact inversion formula for the Lorentz integral transform (LIT) is provided together with the spectrum of the LIT kernel. The exponential increase of the inverse Fourier transform of the LIT kernel entering the inversion formula explains the ill-posed character of the LIT approach. Also the continuous spectrum of the LIT kernel, which approaches zero points necessarily to the same defect. A possible cure is discussed and numerically illustrated.Comment: 13 pages, 3 figure

On the Accuracy of Hyperspherical Harmonics Approaches to Photonuclear Reactions

Using the Lorentz Integral Transform (LIT) method we compare the results for the triton total photodisintegration cross section obtained using the Correlated Hyperspherical Harmonics (CHH) and the Effective Interaction Hyperspherical Harmonics (EIHH) techniques. We show that these two approaches, while rather different both conceptually and computationally, lead to results which coincide within high accuracy. The calculations which include two- and three-body forces are of the same high quality in both cases. We also discuss the comparison of the two approaches in terms of computational efficiency. These results are of major importance in view of applications to the much debated case of the four-nucleon photoabsorption.Comment: 12 pages, 3 figure

DAXX mutations as potential genomic markers of malignant evolution in small nonfunctioning pancreatic neuroendocrine tumors

Management of localized well-differentiated pancreatic neuroendocrine tumors (panNETs) is controversial and primarily dependent on tumor size. Upfront surgery is usually recommended for tumors larger than 2 cm in diameter since they frequently show metastatic potential, whereas smaller panNETs are generally characterized by an indolent clinical course, with a rate of relapse or metastasis below 15%. To explore whether increased tumor size is paralleled by genomic variations, we compared the rate and the mutational patterns of putative driver genes that are recurrently altered in these tumors by investigating differential cohorts of panNET surgical specimens smaller (n = 27) or larger than 2 cm (n = 29). We found that the cumulative number of mutations detected in panNETs >2 cm was significantly higher (p = 0.03) relative to smaller tumors, while mutations of DAXX were significantly more frequent in the cohort of larger tumors (p = 0.05). Moreover, mutations of DAXX were associated with features of malignancy including increased grade, nodal involvement and lymphovascular invasion, and independently predicted both relapse after surgery (p = 0.05) and reduced DFS in multivariable analysis (p = 0.02). Our data suggest that alterations of the DAXX/ATRX molecular machinery increase the malignant potential of panNETs, and that identification of mutations of DAXX/ATRX in small, nonfunctioning tumors can predict the malignant progression observed in a minority of them

Case study: calculation of a narrow resonance with the LIT method

The possibility to resolve narrow structures in reaction cross sections in calculations with the Lorentz integral transform (LIT) method is studied. To this end we consider a fictitious two-nucleon problem with a low-lying and narrow resonance in the $^3P_1$ nucleon-nucleon partial wave and calculate the corresponding ``deuteron photoabsorption cross section''. In the LIT method the use of continuum wave functions is avoided and one works instead with a localized function \tilde\Psi. In this case study it is investigated how far into the asymptotic region \tilde\Psi has to be determined in order to obtain a precise resolution of the artificially introduced E1 resonance. Comparing with the results of a conventional calculation with explicit neutron-proton continuum wave functions it is shown that the LIT approach leads to an excellent reproduction of the cross section in the resonance region and of further finer cross section details at higher energies. To this end, however, for \tilde\Psi one has to take into account two-nucleon distances up to at least 30 fm.Comment: 18 pages, 11 figure

Relationship between Cardiorespiratory Fitness and Anthropometric Variables among school-going adolescents in Nigeria

The increase in physical activity (PA) levels has been known to be associated with improved cardiorespiratory fitness status which helps in reducing the risk factors of non-communicable disease. However, the interaction between cardiorespiratory fitness and anthropometric variables remains unclear and needs further investigation. This study assessed the relationship between cardiorespiratory fitness and anthropometric variables among school-going adolescents in Nigeria. Two hundred and fifty apparently healthy participants ranging from 12 to 20 years of age, who were randomly selected, participated in this study. Height, body weight, and body mass index (BMI) were measured. Cooper’s 12 minutes run/walk test was conducted to assess cardiorespiratory fitness (estimated by maximal oxygen uptake: VO2max). There was a significant correlation betweenVO2max and BMI. In the regression model, weight, height, gender, and BMI accounted for ninety-five percent of the total variance in the participants’ cardiorespiratory fitness. Body weight, height, gender, and BMI were significant predictors of cardiorespiratory fitness in the school-going Nigerian adolescents.IS

Threshold 3He and 3H Transverse Electron Scattering Response Functions

The threshold transverse response functions R_T(q,omega) for 3He and 3H are calculated using the AV18 nucleon-nucleon potential, the UrbanaIX three-body force, and the Coulomb potential. Final states are completely taken into account via the Lorentz integral transform technique. Consistent two-body pi- and rho-meson exchange currents as deduced using the Arenh\"ovel-Schwamb technique are included. The convergence of the method is shown and a comparison of the corresponding MEC contribution is made to that of a consistent MEC for the meson theoretical r-space BonnA potential. The response R_T is calculated in the threshold region at q=174, 324, and 487 MeV/c and compared with available data. The strong MEC contributions in the threshold region are nicely confirmed by the data at q=324 and 487 MeV/c although some differences between theoretical and experimental results remain. A comparison is also made with other calculations, where the same theoretical input is used. The agreement is generally rather good, but leaves also some space for further improvement.Comment: 16 pages, 5 figure

The Thermal Structural Transition of α-Crystallin Inhibits the Heat Induced Self-Aggregation

-crystallin, the major constituent of human lens, is a member of the heat-shock proteins family and it is known to have a quaternary structural transition at . The presence of calcium ions and/or temperature changes induce supramolecular self-aggregation, a process of relevance in the cataractogenesis. Here we investigate the potential effect of the bovine -crystallin's structural transition on the self-aggregation process. Along all the temperatures investigated, aggregation proceeds by forming intermediate molecular assemblies that successively aggregate in clusters. The final morphology of the aggregates, above and below , is similar, but the aggregation kinetics are completely different. The size of the intermediate molecular assemblies, and their repulsive energy barrier show a marked increase while crossing . Our results highlight the key role of heat modified form of -crystallin in protecting from aggregation and preserving the transparency of the lens under hyperthermic conditions