981 research outputs found

    Immigrants and Homeownership in Urban America: An Examination of Nativity, Socio-economic Status and Place

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    A unique pilot project conducted in America's small and medium-sized cities shows that broad-based community coalitions can proactively integrate the newcomers who are increasingly transforming Main St., USA. In the first project of its kind, a consortium of leading organizations in three mid-sized metropolitan areas undertook inclusive community-building. The project's final report contains valuable findings for policymakers, funders and organizations collectively approaching the challenge of helping newcomers adapt to their new communities and local communities welcome newcomers

    Adiabatic fission barriers in superheavy nuclei

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    Using the microscopic-macroscopic model based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy we calculated static fission barriers BfB_{f} for 1305 heavy and superheavy nuclei 98Z12698\leq Z \leq 126, including even - even, odd - even, even - odd and odd - odd systems. For odd and odd-odd nuclei, adiabatic potential energy surfaces were calculated by a minimization over configurations with one blocked neutron or/and proton on a level from the 10-th below to the 10-th above the Fermi level. The parameters of the model that have been fixed previously by a fit to masses of even-even heavy nuclei were kept unchanged. A search for saddle points has been performed by the "Imaginary Water Flow" method on a basic five-dimensional deformation grid, including triaxiality. Two auxiliary grids were used for checking the effects of the mass asymmetry and hexadecapole non-axiallity. The ground states were found by energy minimization over configurations and deformations. We find that the non-axiallity significantly changes first and second fission barrier in many nuclei. The effect of the mass - asymmetry, known to lower the second, very deformed barriers in actinides, in the heaviest nuclei appears at the less deformed saddles in more than 100 nuclei. It happens for those saddles in which the triaxiallity does not play any role, what suggests a decoupling between effects of the mass-asymmetry and triaxiality. We studied also the influence of the pairing interaction strength on the staggering of BfB_f for odd- and even-particle numbers. Finally, we provide a comparison of our results with other theoretical fission barrier evaluations and with available experimental estimates.Comment: submitted to PR

    Superdeformed Oblate Superheavy Nuclei?

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    We study stability of superdeformed oblate (SDO) superheavy Z120Z\geq 120 nuclei predicted by systematic macroscopic-microscopic calculations in 12D deformation space and confirmed by the Hartree-Fock calculations with the realistic SLy6 force. We include into consideration high-KK isomers that very likely form at the SDO shape. Although half-lives T1/2105T_{1/2}\lesssim10^{-5} s are calclulated or estimated for even-even spin zero systems, decay hindrances known for high-KK isomers suggest that some SDO superheavy nuclei may be detectable by the present experimental technique.Comment: 4 pages, 5 figure

    Effect of oxygen plasma on nanomechanical silicon nitride resonators

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    Precise control of tensile stress and intrinsic damping is crucial for the optimal design of nanomechanical systems for sensor applications and quantum optomechanics in particular. In this letter we study the in uence of oxygen plasma on the tensile stress and intrinsic damping of nanomechanical silicon nitride resonators. Oxygen plasma treatments are common steps in micro and nanofabrication. We show that oxygen plasma of only a few minutes oxidizes the silicon nitride surface, creating several nanometer thick silicon dioxide layers with a compressive stress of 1.30(16)GPa. Such oxide layers can cause a reduction of the e ective tensile stress of a 50 nm thick stoichiometric silicon nitride membrane by almost 50%. Additionally, intrinsic damping linearly increases with the silicon dioxide lm thickness. An oxide layer of 1.5nm grown in just 10s in a 50W oxygen plasma almost doubled the intrinsic damping. The oxide surface layer can be e ciently removed in bu ered HF

    UBQLN4 Represses Homologous Recombination and Is Overexpressed in Aggressive Tumors

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    Genomic instability can be a hallmark of both human genetic disease and cancer. We identify a deleterious UBQLN4 mutation in families with an autosomal recessive syndrome reminiscent of genome instability disorders. UBQLN4 deficiency leads to increased sensitivity to genotoxic stress and delayed DNA double-strand break (DSB) repair. The proteasomal shuttle factor UBQLN4 is phosphorylated by ATM and interacts with ubiquitylated MRE11 to mediate early steps of homologous recombination-mediated DSB repair (HRR). Loss of UBQLN4 leads to chromatin retention of MRE11, promoting non-physiological HRR activity in vitro and in vivo. Conversely, UBQLN4 overexpression represses HRR and favors non-homologous end joining. Moreover, we find UBQLN4 overexpressed in aggressive tumors. In line with an HRR defect in these tumors, UBQLN4 overexpression is associated with PARP1 inhibitor sensitivity. UBQLN4 therefore curtails HRR activity through removal of MRE11 from damaged chromatin and thus offers a therapeutic window for PARP1 inhibitor treatment in UBQLN4-overexpressing tumors
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