14 research outputs found
Fine-Scale Mapping of the 4q24 Locus Identifies Two Independent Loci Associated with Breast Cancer Risk
Background: A recent association study identified a common variant (rs9790517) at 4q24 to be associated with breast cancer risk. Independent association signals and potential functional variants in this locus have not been explored.
Methods: We conducted a fine-mapping analysis in 55,540 breast cancer cases and 51,168 controls from the Breast Cancer Association Consortium.
Results: Conditional analyses identified two independent association signals among women of European ancestry, represented by rs9790517 [conditional P = 2.51 × 10−4; OR, 1.04; 95% confidence interval (CI), 1.02–1.07] and rs77928427 (P = 1.86 × 10−4; OR, 1.04; 95% CI, 1.02–1.07). Functional annotation using data from the Encyclopedia of DNA Elements (ENCODE) project revealed two putative functional variants, rs62331150 and rs73838678 in linkage disequilibrium (LD) with rs9790517 (r2 ≥ 0.90) residing in the active promoter or enhancer, respectively, of the nearest gene, TET2. Both variants are located in DNase I hypersensitivity and transcription factor–binding sites. Using data from both The Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC), we showed that rs62331150 was associated with level of expression of TET2 in breast normal and tumor tissue.
Conclusion: Our study identified two independent association signals at 4q24 in relation to breast cancer risk and suggested that observed association in this locus may be mediated through the regulation of TET2.
Impact: Fine-mapping study with large sample size warranted for identification of independent loci for breast cancer risk
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Reactor concepts for laser fusion
Scoping studies were initiated to identify attractive reactor concepts for producing electric power with laser fusion. Several exploratory reactor concepts were developed and are being subjected to our criteria for comparing long-range sources of electrical energy: abundance, social costs, technical feasibility, and economic competitiveness. The exploratory concepts include: a liquid-lithium-cooled stainless steel manifold, a gas-cooled graphite manifold, and fluidized wall concepts, such as a liquid lithium ''waterfall'', and a ceramic-lithium pellet ''waterfall''. Two of the major reactor vessel problems affecting the technical feasibility of a laser fusion power plant are: the effects of high-energy neutrons and cyclical stresses on the blanket structure and the effects of x-rays and debris from the fusion microexplosion on the first-wall. The liquid lithium ''waterfall'' concept is presented here in more detail as an approach which effectively deals with these damaging effects
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Optical design considerations for laser fusion reactors
The plan for the development of commercial inertial confinement fusion (ICF) power plants is discussed, emphasizing the utilization of the unique features of laser fusion to arrive at conceptual designs for reactors and optical systems which minimize the need for advanced materials and techniques requiring expensive test facilities. A conceptual design for a liquid lithium fall reactor is described which successfully deals with the hostile x-ray and neutron environment and promises to last the 30 year plant lifetime. Schemes for protecting the final focusing optics are described which are both compatible with this reactor system and show promise of surviving a full year in order to minimize costly downtime. Damage mechanisms and protection techniques are discussed, and a recommendation is made for a high f-number metal mirror final focusing system
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Liquid metal requirements for inertial confinement fusion
The lithium waterfall reactor is described as a concept in which liquid lithium serves as the coolant, tritium breeder, and 1st-wall and blanket structure protector. This reactor has emerged as a promising concept that alleviates the major problems associated with inertial confinement fusion systems. It eliminates the first wall problems resulting from x-rays and pellet debris, and minimizes cyclical thermal stresses. Also, the thick falling region of lithium attenuates neutrons to the point where the blanket structure could survive for the lifetime of the power plant at high power densities
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Laser driven fusion fission hybrids
The role of the fusion-fission hybrid reactor (FFHR) as a fissile fuel and/or power producer is discussed. As long range options to supply the world energy needs, hybrid-fueled thermal-burner reactors are compared to liquid metal fast breeder reactors (LMFBR). A discussion of different fuel cycles (thorium, depleted uranium, and spent fuel) is presented in order to compare the energy multiplication, the production of fissile fuel, the laser efficiency and pellet gain requirements of the hybrid reactor. LLL has collaborated with Bechtel Corporation and with Westinghouse on the conceptual design of laser fusion power plants. The neutronic studies of these two designs are discussed. The operational parameters, such as energy multiplication, power density, burn-up and plutonium production as a function of time, are also presented
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Design studies of a laser fusion power plant
The conceptual design of a laser fusion power plant has been undertaken to exploit recent developments in target design. Advanced high-gain targets which have been developed make it possible to significantly relax the laser and optical system requirements. The power plant design features a reactor concept which utilizes a thick falling region of liquid lithium to protect the first-wall from the neutrons, x-rays, and charged particles that are produced in the thermonuclear microexplosion. The lithium waterfall has also been designed to be thick enough to significantly reduce the effects of 14 MeV neutrons and cyclical stresses on the blanket structure; thereby allowing us to consider smaller blanket structures which could last the lifetime of the plant. Fusion targets producing 700 MJ of thermonuclear energy are ignited by a 2 percent efficient, 1 MJ laser system at the rate of 1.4 Hz. Schemes for protecting the final focusing optics are described which are both compatible with this reactor system, and show promise of surviving a full year in order to minimize costly downtime
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Conceptual design of a laser fusion power plant
A conceptual design of a laser fusion power plant is extensively discussed. Recent advances in high gain targets are exploited in the design. A smaller blanket structure is made possible by use of a thick falling region of liquid lithium for a first wall. Major design features of the plant, reactor, and laser systems are described. A parametric analysis of performance and cost vs. design parameters is presented to show feasible design points. A more definitive follow-on conceptual design study is planned. (RME