198 research outputs found

    Ex-post Impact Assessment of the Study: 'Impact of Climate Change on Water Resources and Agriculture in Sri Lanka'

    Get PDF
    The assessment revealed that the findings of the study mentioned has significantly influenced Sri Lanka's climate change strategies and policies. The methodology developed by the study has been adopted in the preparation of sector vulnerability profiles that form the basis for the National Climate Change Adaptation Strategy for Sri Lanka:2011 to 2016 and has been referred to in Sri Lanka’s Second National Communication to the United Nations Framework Convention on Climate Change (UNFCCC). The study has generated a demand for capacity building for climate change and vulnerability analysis in government departments where IWMI's input was solicited. The lead author was invited to be a member of expert committees and advisory bodies on climate change set-up by government. Besides, the recommendations from the study have led to an initiative to establish climate stations across Sri Lanka. The main reasons for the broader appeal of the study is the timeliness of the topic and concerted efforts made to engage key stakeholders

    Genomic instability due to V(D)J recombination-associated transposition

    Get PDF
    The first step in assembling immunoglobulin and T-cell receptors by V(D)J recombination has similarities to transposon excision. The excised transposon-like element then integrates into DNA targets at random in vitro, but whether this activity significantly threatens the genomic integrity of its host has been unclear. Here, we recover examples where the putative transposon associated with V(D)J recombination integrated into the genome of a pre-B-cell line. Transposition accounted for a surprisingly high proportion (one-third) of integrations, while most of the remaining events had parallels to other aberrant V(D)J recombination pathways linked to oncogenic translocation. In total, transposition occurred approximately once every 50,000 V(D)J recombinations. Transposition may thus contribute significantly to genomic instability

    V(D)J recombination: Born to be wild

    Get PDF
    Vertebrates employ V(D)J recombination to generate diversity for an adaptive immune response. Born of a transposon, V(D)J recombination could conceivably cause more trouble than it's worth. However, of the two steps required for transposon mobility (excision and integration) this particular transposon's integration step appears mostly blocked in cells. The employment of a transposon as raw material to develop adaptive immunity was thus a less-risky choice than it might have been…but is it completely risk-free

    Quenching of Weak Interactions in Nucleon Matter

    Full text link
    We have calculated the one-body Fermi and Gamow-Teller charge-current, and vector and axial-vector neutral-current nuclear matrix elements in nucleon matter at densities of 0.08, 0.16 and 0.24 fm3^{-3} and proton fractions ranging from 0.2 to 0.5. The correlated states for nucleon matter are obtained by operating on Fermi-gas states by a symmetrized product of pair correlation operators determined from variational calculations with the Argonne v18 and Urbana IX two- and three-nucleon interactions. The squares of the charge current matrix elements are found to be quenched by 20 to 25 % by the short-range correlations in nucleon matter. Most of the quenching is due to spin-isospin correlations induced by the pion exchange interactions which change the isospins and spins of the nucleons. A large part of it can be related to the probability for a spin up proton quasi-particle to be a bare spin up/down proton/neutron. We also calculate the matrix elements of the nuclear Hamiltonian in the same correlated basis. These provide relatively mild effective interactions which give the variational energies in the Hartree-Fock approximation. The calculated two-nucleon effective interaction describes the spin-isospin susceptibilities of nuclear and neutron matter fairly accurately. However \geq 3-body terms are necessary to reproduce the compressibility. All presented results use the simple 2-body cluster approximation to calculate the correlated basis matrix elements.Comment: submitted to PR

    Non-homologous End Joining Requires That the DNA-PK Complex Undergo an Autophosphorylation-dependent Rearrangement at DNA Ends

    Get PDF
    Repair of chromosome breaks by non-homologous end joining requires the XRCC4-ligase IV complex, Ku, and the DNA-dependent protein kinase catalytic subunit (DNA-PKcs). DNA-PKcs must also retain kinase activity and undergo autophosphorylation at six closely linked sites (ABCDE sites). We describe here an end-joining assay using only purified components that reflects cellular requirements for both Ku and kinase-active DNA-PKcs and investigate the mechanistic basis for these requirements. A need for DNA-PKcs autophosphorylation is sufficient to explain the requirement for kinase activity, in part because autophosphorylation is generally required for end-joining factors to access DNA ends. However, DNA-PKcs with all six ABCDE autophosphorylation sites mutated to alanine allows access to ends through autophosphorylation of other sites, yet our in vitro end-joining assay still reflects the defectiveness of this mutant in cellular end joining. In contrast, mutation of ABCDE sites to aspartate, a phosphorylation mimic, supports high levels of end joining that is now independent of kinase activity. This is likely because DNA-PKcs with aspartate substitutions at ABCDE sites allow access to DNA ends while retaining affinity for Ku-bound ends and stabilizing recruitment of the XRCC4-ligase IV complex. Autophosphorylation at ABCDE sites thus apparently directs a rearrangement of the DNA-PK complex that ensures access to broken ends and joining steps are coupled together within a synaptic complex, making repair more accurate

    Neutron matter at zero temperature with auxiliary field diffusion Monte Carlo

    Full text link
    The recently developed auxiliary field diffusion Monte Carlo method is applied to compute the equation of state and the compressibility of neutron matter. By combining diffusion Monte Carlo for the spatial degrees of freedom and auxiliary field Monte Carlo to separate the spin-isospin operators, quantum Monte Carlo can be used to simulate the ground state of many nucleon systems (A\alt 100). We use a path constraint to control the fermion sign problem. We have made simulations for realistic interactions, which include tensor and spin--orbit two--body potentials as well as three-nucleon forces. The Argonne v8v_8' and v6v_6' two nucleon potentials plus the Urbana or Illinois three-nucleon potentials have been used in our calculations. We compare with fermion hypernetted chain results. We report results of a Periodic Box--FHNC calculation, which is also used to estimate the finite size corrections to our quantum Monte Carlo simulations. Our AFDMC results for v6v_6 models of pure neutron matter are in reasonably good agreement with equivalent Correlated Basis Function (CBF) calculations, providing energies per particle which are slightly lower than the CBF ones. However, the inclusion of the spin--orbit force leads to quite different results particularly at relatively high densities. The resulting equation of state from AFDMC calculations is harder than the one from previous Fermi hypernetted chain studies commonly used to determine the neutron star structure.Comment: 15 pages, 15 tables and 5 figure

    A predictive preoperative and postoperative nomogram for postoperative potency recovery after robot-assisted radical prostatectomy

    Get PDF
    Purpose: Prediction of potency recovery following robot-assisted radical prostatectomy (RARP) is useful for better patient counseling and postoperative treatment strategies. In this study we propose a preoperative and postoperative nomogram to predict postoperative potency recovery following RARP.Materials and Methods: Patients from development set (6,502) were selected to develop the nomograms, and patients in validation set (2,706) were used for validation. Cox regression models were fitted on the development cohort to predict potency recovery after RARP using as prognostic factors the covariates selected. Two nomograms were drawn using the regression coefficients of the preoperative and postoperative Cox models.Results: The discrimination ability of the preoperative model was evaluated on the development cohort using the receiver operator curves estimated at 3, 6, 12 and 24 months. The AUC at these time points was 0.726, 0.734, 0.754, and 0.778, respectively. The areas under the curve of the postoperative model at 3, 6, 12 and 24 months were 0.746, 0.756 and 0.777, and 0.801, respectively. Preoperative and postoperative predictive models were validated using a separate set of 2,706 patients. The AUCs of the preoperative model at 3, 6, 12 and 24 months were 0.789, 0.772, 0.768, and 0.778, respectively. The ROC curves of the postoperative model at 3, 6, 12 and 24 months with AUCs of 0.807, 0.797, 0.793 and 0.798, respectively. Along with age and preoperative sexual function, nerve-sparing technique determines the potency outcomes justifying better AUC for postoperative model vs the preoperative model.Conclusions: The above nomograms help us to predict with good accuracy the probability of potency recovery within 3, 6, 12 and 24 months following surgery taking into consideration preoperative and postoperative factors. This is a novel tool for the care giver to predict realistic expectation of potency outcomes to the patients, while preoperative and immediate postoperative counseling
    corecore