49 research outputs found

    Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

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    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

    Electronic Structure of Zinc-Blende and Hexagonal Semiconductors: Comparative Theoretical Study

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    Using a self-consistent Korringa-Kohn-Rostoker Green function method and the local density approximation for the exchange and correlation potentials, we calculated the electronic structure and the corresponding densities of states for two semiconducting compounds that exist in both cubic (zinc-blende) and hexagonal (wurtzite and NiAs-type) crystal structures, i.e., for CdSe and MnTe. Due to the use of the same method of calculation for both structures a comparison between the obtained results and finding the factors that determine the difference between the properties of these two phases are possible. The presented local density approximation-Korringa-Kohn-Rostoker results might be of importance for the understanding of the factors that determine the relative stability of different phases of semiconducting compounds

    Influence of the intelligent transport systems reliability on the use of the road network

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    The Intelligent Transport Systems used in the public transport can be described in a following manner: it is a collection of properly designed complex devices, which create island systems, followed by their integration that creates one, centrally managed traffic control system in the whole road, or city area. Authors will present here information regarding the usability of the above mentioned systems for the interested parties. Reliability is an important factor in such systems, as the ITS that consist of many complex objects must be characterized by low level of errors. The utility value of the ITS drops significantly in case of large damages intensity in devices that are part of the system. Deliberations presented here are based on experiences with installation and exploitation of the ITS at class A and S roads

    Formation Energy and Electronic Structure of II-VI/IV Semiconductor Superlattices

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    We calculate formation energy and electronic structure of ultrathin (001)II-VI/IV semiconductor superlattices using the Korringa-Kohn-Rostoker all-electron method. Formation energies (∆H) are 2.18 eV for (Ge2\text{}_{2})1\text{}_{1}(ZnSe)1\text{}_{1} and 1.50 eV for (ZnS)1\text{}_{1}(Si2\text{}_{2})1\text{}_{1}. The results of this work are significantly different from these by Ferraz and Srivastava who obtained ∆H = 0.88 eV for (001)(Ge2\text{}_{2})1\text{}_{1}(ZnSe)1\text{}_{1} and moreover the one-layer super-lattices are metallic, which confirms the results by Ohno and Ito. The large formation energies surely lead to interfacial instability

    Data from: No support for the sexy‐sperm hypothesis in the seed beetle: sons of monandrous females fare better in post‐copulatory competition

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    The sexy-sperm hypothesis posits that polyandrous females derive an indirect fitness benefit from multi-male mating because they increase the probability their eggs are fertilized by males whose sperm have high fertilizing efficiency, which is assumed to be heritable and conferred on their sons. However, whether this process occurs is contentious because father-to-son heritability may be constrained by the genetic architecture underlying traits important in sperm competition within certain species. Previous empirical work has revealed such genetic constraints in the seed beetle, Callosobruchus maculatus, a model system in sperm competition studies in which female multi-male mating is ubiquitous. Using the seed beetle, I tested a critical prediction of the sexy-sperm hypothesis that polyandrous females produce sons that are on average more successful under sperm competition than sons from monandrous females. Contrary to the prediction of the sexy-sperm hypothesis, I found that sons from monandrous females had significantly higher relative paternity in competitive double matings. Moreover, post-hoc analyses revealed that these sons produced significantly larger ejaculates when second to mate, despite being smaller. This study is the first to provide empirical evidence for post-copulatory processes favoring monandrous sons and discusses potential explanations for the unexpected bias in paternity

    Clinical implications of glucocorticoid receptors in human leukemia

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    Normal lymphoid cells contain glucocorticoid receptor. A variety of stimuli that activate these cells also induce increases in receptor concentration. Similar glucocorticoid receptors can be detected in lymphoid cells from patients with acute lymphoblastic leukemia (ALL). Absence of the glucocorticoid receptor (usually found in treated patients) predicts lack of glucocorticoid responsiveness. Furthermore, in our hands, glucocorticoid receptor levels correlate with the duration of complete remission in ALL (though not in other forms of leukemia). This association is independent of cell type, age, sex, or initial leukocyte count. The level of receptor shows a negative correlation with increasing aggressiveness of the tumor (null-cell leukemia greater than T-cell leukemia greater than Burkitt's lymphoma)
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