285 research outputs found

    Laser Patterning of High‐Mass‐Loading Graphite Anodes for High‐​Performance Li‐​Ion Batteries

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    Given the ongoing efforts to build Li-ion batteries with higher volumetric energy and power densities, the research on enhancing Li-ion transport within compressed high-mass-loading electrodes at fast cycling conditions is imperative. In this work, we show that the rate capability of graphite electrodes with high areal capacity of 4.5 mAh cm2 and density of 1.79 g cm3 (15% of porosity) can be considerably improved by laser patterning, namely by the fabrication of arrays of vertically aligned channels serving as diffusion paths for rapid Li-ion transport. Resultant laser patterned graphite electrodes delivered enhanced volumetric capacity as compared to that of non-patterned electrodes (450 vs. 396 mAh cm3 at C/2 rate). The reduction of the total steady-state concentration drop within the graphite electrodes after their patterning was also assessed

    DNA methylation plays a crucial role during early <i>Nasonia</i> development

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    Although the role of DNA methylation in insect development is still poorly understood, the number and role of DNA methyltransferases in insects vary strongly between species. DNA methylation appears to be widely present among the social hymenoptera and functional studies in Apis have suggested a crucial role for de novo methylation in a wide variety of developmental processes. The sequencing of three parasitoid Nasonia genomes revealed the presence of three Dnmt1 (Dnmt1a, Dnmt1b and Dnmt1c) genes and one Dnmt2 and Dnmt3 gene, suggesting a role of DNA methylation in Nasonia development. In the present study we show that in Nasonia vitripennis all Dnmt1 messenger RNAs (mRNAs) and Dnmt3 mRNA are maternally provided to the embryo and, of these, Dnmt1a is essential during early embryogenesis. Lowering of maternal Dnmt1a mRNA results in embryonic lethality during the onset of gastrulation. This dependence on maternal Dnmt1a during embryogenesis in an organismal group outside the vertebrates, suggests evolutionary conservation of the function of Dnmt1 during embryogenesis.</p

    Variation with mass of \boldmath{B(E3; 0_1^+ \to 3_1^-)} transition rates in A=124134A=124-134 even-mass xenon nuclei

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    B(E3;01+31)B(E3; 0_1^+ \to 3_1^-) transition matrix elements have been measured for even-mass 124134^{124-134}Xe nuclei using sub-barrier Coulomb excitation in inverse kinematics. The trends in energy E(3)E(3^-) and B(E3;01+31)B(E3; 0_1^+ \to 3_1^-) excitation strengths are well reproduced using phenomenological models based on a strong coupling picture with a soft quadrupole mode and an increasing occupation of the intruder h11/2h_{11/2} orbital.Comment: 5 pages, 4 figures, PRC in pres

    Diversifying selection and color-biased dispersal in the asp viper.

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    BACKGROUND: The presence of intraspecific color polymorphism can have multiple impacts on the ecology of a species; as a consequence, particular color morphs may be strongly selected for in a given habitat type. For example, the asp viper (Vipera aspis) shows a high level of color polymorphism. A blotched morph (cryptic) is common throughout its range (central and western Europe), while a melanistic morph is frequently found in montane populations, presumably for thermoregulatory reasons. Besides, rare atypical uniformly colored individuals are known here and there. Nevertheless, we found in a restricted treeless area of the French Alps, a population containing a high proportion (&gt;50%) of such specimens. The aim of the study is to bring insight into the presence and function of this color morph by (i) studying the genetic structure of these populations using nine microsatellite markers, and testing for (ii) a potential local diversifying selection and (iii) differences in dispersal capacity between blotched and non-blotched vipers. RESULTS: Our genetic analyses support the occurrence of local diversifying selection for the non-blotched phenotype. In addition, we found significant color-biased dispersal, blotched individuals dispersing more than atypical individuals. CONCLUSION: We hypothesize that, in this population, the non-blotched phenotype possess an advantage over the typical one, a phenomenon possibly due to a better background matching ability in a more open habitat. In addition, color-biased dispersal might be partly associated with the observed local diversifying selection, as it can affect the genetic structure of populations, and hence the distribution of color morphs

    Z=50 shell gap near 100^{100}Sn from intermediate-energy Coulomb excitations in even-mass 106112^{106--112}Sn isotopes

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    Rare isotope beams of neutron-deficient 106,108,110^{106,108,110}Sn nuclei from the fragmentation of 124^{124}Xe were employed in an intermediate-energy Coulomb excitation experiment yielding B(E2,01+21+)B(E2, 0^+_1 \to 2^+_1) transition strengths. The results indicate that these B(E2,01+21+)B(E2,0^+_1 \to 2^+_1) values are much larger than predicted by current state-of-the-art shell model calculations. This discrepancy can be explained if protons from within the Z = 50 shell are contributing to the structure of low-energy excited states in this region. Such contributions imply a breaking of the doubly-magic 100^{100}Sn core in the light Sn isotopes.Comment: 4 pages, 4 figure

    XHIP-II: Clusters and associations

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    Context. In the absence of complete kinematic data it has not previously been possible to furnish accurate lists of member stars for all moving groups. There has been an unresolved dispute concerning the apparent inconsistency of the Hipparcos parallax distance to the Pleiades. Aims. To find improved candidate lists for clusters and associations represented among Hipparcos stars, to establish distances, and to cast light on the Pleiades distance anomaly. Methods. We use a six dimensional fitting procedure to identify candidates, and plot CMDs for 20 of the nearest groups. We calculate the mean parallax distance for all groups. Results. We identify lists of candidates and calculated parallax distances for 42 clusters and 45 associations represented within the Hipparcos catalogue. We find agreement between parallax distance and photometric distances for the most important clusters. For single stars in the Pleiades we find mean parallax distance 125.6 \pm 4.2 pc and photometric distance 132 \pm 3 pc calibrated to nearby groups of similar in age and composition. This gives no reason to doubt either the Hipparcos database or stellar evolutionary theory.Comment: Accepted for publication in Astronomy Letters, 10 pages, 2 fig

    Evaluating the effects of bilingual traffic signs on driver performance and safety

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    Variable Message Signs (VMS) can provide immediate and relevant information to road users and bilingual VMS can provide great flexibility in countries where a significant proportion of the population speak an alternative language to the majority. The study reported here evaluates the effect of various bilingual VMS configurations on driver behaviour and safety. The aim of the study was to determine whether or not the visual distraction associated with bilingual VMS signs of different configurations (length, complexity) impacted on driving performance. A driving simulator was used to allow full control over the scenarios, road environment and sign configuration and both longitudinal and lateral driver performance was assessed. Drivers were able to read one and two-line monolingual signs and two-line bilingual signs without disruption to their driving behaviour. However, drivers significantly reduced their speed in order to read four-line monolingual and four-line bilingual signs, accompanied by an increase in headway to the vehicle in front. This implies that drivers are possibly reading the irrelevant text on the bilingual sign and various methods for reducing this effect are discussed

    Evidence of time-dependent CP violation in the decay B0 to D*+D*-

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    We report a measurement of the CP-odd fraction and the time-dependent CP violation in B0 to D*+D*- decays, using 657.10^6 BBbar events collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We measure a CP-odd fraction of Rperp=0.125+/-0.043(stat)+/-0.023(syst). From the distributions of the proper-time intervals between a B0to D*+D*- decay and the other B meson in the event, we obtain evidence of CP violation with measured parameters AD*+D*-=0.15+/-0.13(stat)+/-0.04(syst) and SD*+D*-=-0.96+/-0.25(stat)-0.16+0.13(syst).Comment: Published in PR
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