The effect of high-pressure torsion on irradiation hardening of Eurofer-97

We investigate the effect of nano-structuring by high-pressure torsion (HPT) on the irradiation performance of Eurofer-97. Material was deformed to shear strains from 0 to ∼230, and then exposed to Fe3+ irradiation doses of 0.01 and 0.1 displacements-per-atom (dpa). Nanoindentation hardness increases monotonically with deformation, and with irradiation for the undeformed material. For both damage levels, less irradiation hardening is observed in severely deformed material. This effect is most prominent in the strain range ∼60 to ∼160, suggesting that nano-structuring may provide an approach for reducing irradiation hardening

Beam Splitter for Spin Waves in Quantum Spin Network

We theoretically design and analytically study a controllable beam splitter for the spin wave propagating in a star-shaped (e.g., a $Y$-shaped beam) spin network. Such a solid state beam splitter can display quantum interference and quantum entanglement by the well-aimed controls of interaction on nodes. It will enable an elementary interferometric device for scalable quantum information processing based on the solid system.Comment: 5 pages, 4 figures, derivation of formulae change

Herpes Simplex Virus 1 ICP27 Is Required for Transcription of Two Viral Late (γ2) Genes in Infected Cells

AbstractThe herpes simplex virus infected cell protein 27 (ICP27) is required for the expression of certain early viral proteins and for many late proteins during productive infection. Expression of at least one late (γ2) gene, that encoding glycoprotein C, is severely restricted in the absence of functional ICP27. The exact mode of action by which ICP27 induces late gene expression is not known, but the effect is apparent at the mRNA level as demonstrated by Northern blot analysis. To determine whether ICP27 activates late genes via transcriptional or posttranscriptional mechanisms, we initially used nuclear run-on assays to measure transcription of viral genes in Vero cells infected with wild-type (WT) virus or an ICP27 nonsense mutant virus, n504. We observed a 4-fold reduction in the nuclear run-on signal from the coding strand of the gC gene for n504-infected cells compared to that of WT-infected cells. However, interpretation of the results was complicated by the observation of a significant signal from the noncoding strand in these experiments. To obviate the problem of symmetrical transcription, we utilized in vivo RNA pulse-labeling to measure the amount of transcription of viral genes in cells infected with either WT virus or n504 virus. We found a 5- to 10-fold reduction in the transcription of the gC and UL47 genes, two late genes, in cells infected with n504 compared to that in cells infected with WT virus. In contrast, transcription of the ICP8 gene, an early gene, was similar in WT and n504 virus-infected cells. We also examined the stability of the gC and UL47 gene transcripts in n504-infected cells, and we found it to be comparable to that in WT virus-infected cells, further supporting an effect on transcription. Transcription of the gC and UL47 genes by n504 was normal in a cell line that expresses WT ICP27. From these results we conclude that ICP27 is required for transcription of the late gC and UL47 genes during productive infection

A Scalable Test Problem Generator for Sequential Transfer Optimization

Sequential transfer optimization (STO), which aims to improve optimization performance by exploiting knowledge captured from previously-solved optimization tasks stored in a database, has been gaining increasing research attention in recent years. However, despite significant advancements in algorithm design, the test problems in STO are not well designed. Oftentimes, they are either randomly assembled by other benchmark functions that have identical optima or are generated from practical problems that exhibit limited variations. The relationships between the optimal solutions of source and target tasks in these problems are manually configured and thus monotonous, limiting their ability to represent the diverse relationships of real-world problems. Consequently, the promising results achieved by many algorithms on these problems are highly biased and difficult to be generalized to other problems. In light of this, we first introduce a few rudimentary concepts for characterizing STO problems (STOPs) and present an important problem feature overlooked in previous studies, namely similarity distribution, which quantitatively delineates the relationship between the optima of source and target tasks. Then, we propose general design guidelines and a problem generator with superior extendibility. Specifically, the similarity distribution of a problem can be systematically customized by modifying a parameterized density function, enabling a broad spectrum of representation for the diverse similarity relationships of real-world problems. Lastly, a benchmark suite with 12 individual STOPs is developed using the proposed generator, which can serve as an arena for comparing different STO algorithms. The source code of the benchmark suite is available at https://github.com/XmingHsueh/STOP

Deformation behaviour of ion-irradiated FeCr : A nanoindentation study

Understanding the mechanisms of plasticity in structural steels is essential for the operation of next-generation fusion reactors. This work on the deformation behaviour of FeCr, focusses on distinguishing the nucleation of dislocations to initiate plasticity, from their propagation through the material. Fe3Cr, Fe5Cr, and Fel OCr were irradiated with 20 MeV Fe3+ ions at room temperature to doses of 0.008 dpa and 0.08 dpa. Nanoindentation was then carried out with Berkovich and spherical indenter tips. Our results show that the nucleation of dislocations is mainly from pre-existing sources, which are not significantly affected by the presence of irradiation defects or Cr%. Yield strength, an indicator of dislocation mobility, increases with irradiation damage and Cr content, while work hardening capacity decreases mainly due to irradiation defects. The synergistic effects of Cr and irradiation damage in FeCr appear to be more important for the propagation of dislocations than for their nucleation.Peer reviewe

Polarization Switching Dynamics Governed by Thermodynamic Nucleation Process in Ultrathin Ferroelectric Films

A long standing problem of domain switching process - how domains nucleate - is examined in ultrathin ferroelectric films. We demonstrate that the large depolarization fields in ultrathin films could significantly lower the nucleation energy barrier (U*) to a level comparable to thermal energy (kBT), resulting in power-law like polarization decay behaviors. The "Landauer's paradox": U* is thermally insurmountable is not a critical issue in the polarization switching of ultrathin ferroelectric films. We empirically find a universal relation between the polarization decay behavior and U*/kBT.Comment: 5 pages, 4 figure

A comparison of Pentecostals in Hong Kong, Singapore and Kuala Lumpur: Culture and Belief

Using empirical and quantitative methods Pentecostal ministers are compared in the three locations of Hong Kong, Singapore and Kuala Lumpur. After providing an account of the historical backgrounds of Pentecostal churches in these locations, similarities and differences in the samples may be attributed to environmental or cultural effects. The paper concludes that there is evidence that cultural differences affect the views of respondents in a variety of measurable ways including in their opinion of ecumenical cooperation and in their attitudes to the poor or disadvantaged

Pathogenic infection of Macaca nemestrina with a CCR5-tropic subtype-C simian-human immunodeficiency virus

Background: Although pig-tailed macaques (Macaca nemestrina) have been used in AIDS research for years, less is known about the early immunopathogenic events in this species, as compared to rhesus macaques (Macaca mulatta). Similarly, the events in early infection are well-characterized for simian immunodeficiency viruses (SIV), but less so for chimeric simian-human immunodeficiency viruses (SHIV), although the latter have been widely used in HIV vaccine studies. Here, we report the consequences of intrarectal infection with a CCR5-tropic clade C SHIV-1157ipd3N4 in pig-tailed macaques. Results: Plasma and cell-associated virus was detectable in peripheral blood and intestinal tissues of all four pig-tailed macaques following intrarectal inoculation with SHIV-1157ipd3N4. We also observed a rapid and irreversible loss of CD4+ T cells at multiple mucosal sites, resulting in a marked decrease of CD4:CD8 T cell ratios 0.5–4 weeks after inoculation. This depletion targeted subsets of CD4+ T cells expressing the CCR5 coreceptor and having a CD28-CD95+ effector memory phenotype, consistent with the R5-tropism of SHIV-1157ipd3N4. All three animals that were studied beyond the acute phase seroconverted as early as week 4, with two developing cross-clade neutralizing antibody responses by week 24. These two animals also demonstrated persistent plasma viremia for >48 weeks. One of these animals developed AIDS, as shown by peripheral blood CD4+ T-cell depletion starting at 20 weeks post inoculation. Conclusion: These findings indicate that SHIV-1157ipd3N4-induced pathogenesis in pig-tailed macaques followed a similar course as SIV-infected rhesus macaques. Thus, R5 SHIV-C-infection of pig-tailed macaques could provide a useful and relevant model for AIDS vaccine and pathogenesis research

Deformation localisation in ion-irradiated Fe and Fe10Cr

Determining the mechanisms for irradiation-induced ductility loss is crucial for the design of reactor structural components. Here, the deformation characteristics around nanoindents in Fe and Fe10Cr irradiated with Fe ions to ∼1 displacement-per-atom at 313 K are non-destructively studied. Slip steps surrounding the nanoindents indicate that deformation is localised in the irradiated materials. Lattice rotation and strain fields near the indent site show over 87% confinement of plasticity in the irradiated material. Cr has little effect on the irradiation-induced changes in pile-up topography and deformation fields, suggesting it has limited impact on retaining strain hardening capacity and reducing irradiation-induced embrittlement