48 research outputs found

    Lawson criterion for ignition exceeded in an inertial fusion experiment

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    For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

    Rapid loss of flight in the Aldabra white-throated rail

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    Flight loss has evolved independently in numerous island bird lineages worldwide, and particularly in rails (Rallidae). The Aldabra white-throated rail (Dryolimnas [cuvieri] aldabranus) is the last surviving flightless bird in the western Indian Ocean, and the only living flightless subspecies within Dryolimnas cuvieri, which is otherwise volant across its extant range. Such a difference in flight capacity among populations of a single species is unusual, and could be due to rapid evolution of flight loss, or greater evolutionary divergence than can readily be detected by traditional taxonomic approaches. Here we used genetic and morphological analyses to investigate evolutionary trajectories of living and extinct Dryolimnas cuvieri subspecies. Our data places D. [c.] aldabranus among the most rapid documented avian flight loss cases (within an estimated maximum of 80,000–130,000 years). However, the unusual intraspecific variability in flight capacity within D. cuvieri is best explained by levels of genetic divergence, which exceed those documented between other volant taxa versus flightless close relatives, all of which have full species status. Our results also support consideration of Dryolimnas [cuvieri] aldabranus as sufficiently evolutionary distinct from D. c. cuvieri to warrant management as an evolutionary significant unit. Trait variability among closely related lineages should be considered when assessing conservation status, particularly for traits known to influence vulnerability to extinction (e.g. flightlessness)

    Dimethyl-Sulfoxide Induces a Reduced Growth-Rate, Altered Cell Morphology and Increased Epidermal-Growth-Factor Binding in Hep G2 Cells

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    Culture of Hep G2 cells in medium containing 2 % (v/v) dimethyl sulphoxide (DMSO) resulted in a slowing of growth and a marked change in morphological appearance. By day 6, cultures containing DMSO had one-third the number of cells compared with parallel control cultures. Measurement of I-125-epidermal-growth-factor (EGF) binding to DMSO-treated cells revealed a striking time-dependent elevation in specific EGF binding to their cell surface. Increased binding was detectable within 24 h of the start of DMSO treatment, reaching, by 6 days, levels almost 25 times greater than those for control cells. Addition of EGF to DMSO-treated cells caused a rapid down-regulation of the EGF receptor, but did not alter their proliferation rate. Slowing of growth by other means, such as serum starvation, growth to confluence or culture in the presence of sodium butyrate, did not affect I-125-EGF binding, indicating a specific effect of DMSO on these cells

    Prostate specific antigen levels following transurethral resection of the prostate

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    OBJECTIVE: Determine how serum prostate-specific antigen (t-PSA) levels and free PSA (f/t PSA) ratio change following transurethral resection of the prostate (TURP). MATERIALS AND METHODS: Thirty men with a mean age of 67.0 + 4.2 years (range 46 to 84 years) underwent TURP for BPH between May 2005 and October 2005. Preoperative assessment included symptom evaluation with the International Prostate Symptom Score (I-PSS) and the prostate volume estimation by transrectal ultrasound. Total PSA and f/t PSA ratio were assessed before the procedure, as well as 30, 60 and 180 days after the TURP. RESULTS: Clinical improvement after TURP, reflected by I-PSS score, was demonstrated as early as 30 days and remained stable until the end of the follow-up. Mean t-PSA declined 71% after TURP and 60 days after surgery the reduction reached its peak, stabilizing afterwards. It varied from 6.19 + 7.06 ng/mL before surgery to 1.75 + 1.66 ng/mL on day 60 (p < 0.001). The mean baseline f/t PSA ratio was 18.2% + 3.4% and was not significantly changed at any given time point in the postoperative period (p = 0.91). There were also no statistically significant differences in t-PSA or f/t PSA between patients with and without prostatitis at any time point (p = 0.23). Resected prostate fragments weighed 29.9 + 19.6 g, corresponding to 39.1% of the estimated preoperative prostate volume. Each gram of tissue resected decreased PSA by 0.15 + 0.11 ng/mL, while 1% prostate volume resected led to a reduction of 2.4% + 0.4% in serum PSA from baseline. CONCLUSIONS: PSA decreases drastically in patients who undergo TURP. These low levels stabilize within 60 days after surgery. The f/t PSA ratio did not change, and the finding of chronic prostatitis did not affect the levels of these variables
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