On the double and triple-humped fission barriers and half-lives of actinide elements

The deformation barriers standing in the quasi-molecular shape path have been determined in the actinide region within a macroscopic-microscopic energy derived from a generalized liquid drop model, the algebraic droplet model shell corrections and analytic expressions for the pairing energies. Double and triple-humped fission barriers appear. The second barrier corresponds to the transition from one-body shapes to two touching ellipsoids. The third minimum and third peak, when they exist, come from shell rearrangements in the deformed fragment. The shape of the other almost magic one is close to the sphere. The barrier heights agreewith the experimental results, the energy of the second minimum being a little too high. The predicted half-lives follow the experimental data trend

Coefficients and terms of the liquid drop model and mass formula

The coefficients of different combinations of terms of the liquid drop model have been determined by a least square fitting procedure to the experimental atomic masses. The nuclear masses can also be reproduced using a Coulomb radius taking into account the increase of the ratio $R\_0/A^{1/3}$ with increasing mass, the fitted surface energy coefficient remaining around 18 MeV

A study of the links in between the ASPPs and the Wnt/beta-catenin signalling pathway

The identification of the ASPP family of proteins has helped towards a better understanding of how the function of the tumour suppressor p53 could be specifically regulated. Hence, ASPP1 and ASPP2 bind to- and specifically enhance the transactivation function of p53 on the promoters of proapoptotic genes, whereas iASPP acts as an inhibitor. However, yeast-two-hybrid experiments have shown that the ASPPs, and in particular ASPP2, also interacts with a large number of proteins involved in other major signalling pathways, suggesting that they could be a multi-function family of proteins. One of ASPP2-interacting partners is Adenomatous Polyposis Coli 2/L (APC2/APCL). APCL is a central nervous system-specific homologue of APC, a key factor in the Wnt signalling pathway. As the biological significance of this interaction remains unknown, we explored the interplay between the ASPPs and the APC family. We show that APC and APCL can affect the subcellular localization of ASPP1 and ASPP2 as well as positively regulate their function on p53. As APCL, like APC. is believed to be able to target p-catenin for degradation, we investigated whether ASPP2 could play a role in the regulation of P-catenin. Herein, we show that ASPP2 is a negative regulator of p-catenin transcriptional activity and that they can form a complex at the level of the adherens junctions. In vivo, ASPP2-null mice exhibit severe anomalies in the central nervous system (CNS) formation during embryonic development. Hence, the eyes and the brain were characterized by increased number of cells, poor cellular differentiation and tissue disorganization. Cells expressing nuclear p-catenin were found in a very limited and organized apical region of the developing cortex in the wild-type, whereas in the ASPP2-deficient embryos, they were disseminated throughout the overgrown regions of the brain, suggesting that ASPP2 may regulate p-catenin function during CNS development. Finally, the involvement of ASPP2 in the regulation of p-catenin transcriptional activity could contribute to its function as a tumour suppressor and, importantly, its role in epithelial integrity suggests that it could be determinant in preventing cellular invasion and metastasis

Baroclinic transport in the Gulf of Alaska Part I. Seasonal variations of the Alaska Current

Temperature and salinity sections which intersect the Alaska Current are used to determine the baroclinic, geostropbic current on 21 occasions from 1975 to 1977. A sinusoidal curve-fitting technique is applied to these Alaska Current estimates and others available in the literature to statistically test the flow for an annual signal...

Baroclinic transport in the Gulf of Alaska Part II. A fresh water driven coastal current

A coastal geostrophic, baroclinic jet in the Gulf of Alaska is driven seasonally by fresh water discharge and winds. The narrow current (\u3c20 km) has a mean transport of 0.24 × 106 m3 s-1 (relative to 100 db) and velocities in excess of 66 cm s-1. The jet reaches a maximum in autumn, coincident with maximum fresh water discharge along the coast...

Entrance channels and alpha decay half-lives of the heaviest elements

The barriers standing against the formation of superheavy elements and their consecutive $\alpha$ decay have been determined in the quasimolecular shape path within a Generalized Liquid Drop Model including the proximity effects between nucleons in a neck, the mass and charge asymmetry, a precise nuclear radius and the shell effects given by the Droplet Model. For moderately asymmetric reactions double-hump potential barriers stand and fast fission of compact shapes in the outer well is possible. Very asymmetric reactions lead to one hump barriers which can be passed only with a high energy relatively to the superheavy element energy. Then, only the emission of several neutrons or an $\alpha$ particle can allow to reach an eventual ground state. For almost symmetric heavy-ion reactions, there is no more external well and the inner barrier is higher than the outer one

Multiple-humped fission and fusion barriers of actinide and superheavy elements

The energy of a deformed nucleus has been determined within a Generalized Liquid Drop Model taking into account the proximity energy, the microscopic corrections and quasi-molecular shapes. In the potential barrier a third peak exists for actinides when one fragment is close to a magic spherical nucleus while the other one varies from oblate to prolate shapes. The barrier heights and half-lives agree with the experimental data. The different entrance channels leading possibly to superheavy elements are studied as well as their $\alpha$-decay