The response of a neutral atom to a strong laser field probed by transient absorption near the ionisation threshold

We present transient absorption spectra of an extreme ultraviolet attosecond pulse train in helium dressed by an 800 nm laser field with intensity ranging from $2times10^{12}$ W/cm$^2$ to $2times10^{14}$ W/cm$^2$. The energy range probed spans 16-42 eV, straddling the first ionisation energy of helium (24.59 eV). By changing the relative polarisation of the dressing field with respect to the attosecond pulse train polarisation we observe a large change in the modulation of the absorption reflecting the vectorial response to the dressing field. With parallel polarized dressing and probing fields, we observe significant modulations with periods of one half and one quarter of the dressing field period. With perpendicularly polarized dressing and probing fields, the modulations of the harmonics above the ionisation threshold are significantly suppressed. A full-dimensionality solution of the single-atom time-dependent Schr odinger equation obtained using the recently developed ab-initio time-dependent B-spline ADC method reproduce some of our observations

Atmospheric electrification in dusty, reactive gases in the solar system and beyond

Detailed observations of the solar system planets reveal a wide variety of local atmospheric conditions. Astronomical observations have revealed a variety of extrasolar planets none of which resembles any of the solar system planets in full. Instead, the most massive amongst the extrasolar planets, the gas giants, appear very similar to the class of (young) Brown Dwarfs which are amongst the oldest objects in the universe. Despite of this diversity, solar system planets, extrasolar planets and Brown Dwarfs have broadly similar global temperatures between 300K and 2500K. In consequence, clouds of different chemical species form in their atmospheres. While the details of these clouds differ, the fundamental physical processes are the same. Further to this, all these objects were observed to produce radio and X-ray emission. While both kinds of radiation are well studied on Earth and to a lesser extent on the solar system planets, the occurrence of emission that potentially originate from accelerated electrons on Brown Dwarfs, extrasolar planets and protoplanetary disks is not well understood yet. This paper offers an interdisciplinary view on electrification processes and their feedback on their hosting environment in meteorology, volcanology, planetology and research on extrasolar planets and planet formation

Therapeutic regulation of cardiac fibroblast function: targeting stress-activated protein kinase pathways

Cardiac fibroblasts are key players in the myocardial remodeling process and respond to myocardial damage or dysfunction by adopting a myofibroblast phenotype and undergoing increased proliferation, migration, secretion of bioactive molecules and turnover of the extracellular matrix. Many of the key cellular responses of the heart to injury or stress are mediated via specific signaling cascades involving the stress-activated protein kinases (SAPKs). The SAPKs comprise the p38 MAPK and c-Jun N-terminal kinase families, both of which have been implicated in promoting myocardial damage and adverse cardiac remodeling. This article focuses on SAPK signaling cascades in the heart, with particular emphasis on their modulatory effects on cardiac fibroblast function, inflammation and fibrosis. It also describes current and future therapeutic strategies for inhibiting SAPKs in the myocardium. Understanding the role of SAPK signaling at the cellular level holds potential for developing novel therapies to ameliorate cardiac dysfunction in man

The Echo of After-Poetry: Hans Bethge and the Chinese Lyric

The publication, in 1908, of Hans Bethge’s Die chinesische Flöte marked a highpoint in the reception of Chinese poetry in modern Europe. Bethge’s ‘Nachdichtungen’ (‘after-poems’) of poems from the Tang dynasty through to the late 1800s were extraordinarily popular, and were almost immediately immortalized by Gustav Mahler’s decision to use a selection from them as the text for Das Lied von der Erde (1909). Yet Bethge could not read Chinese, and so based his poems on existing translations by figures including Judith Gautier, whose Livre de Jade had appeared in 1867. This article situates Bethge’s reception of Chinese poetry – and in particular, that of Li-Tai-Po (Li Bai) – within the context of European chinoiserie, notably by concentrating on his engagement with a recurring imagery of lyrics and Lieder. Although he was deaf to the music of Chinese, Bethge was extremely sensitive to the ways in which Li-Tai-Po’s self-conscious reflections on poetic creation underlay his ‘after-poems’ or Nachdichtungen, deriving his impetus from images of the rebirth of prose – songs, birdsong, lyrics, Lieder – as poetry. The very form of the ‘lyric’ emerges as predicated on its function as echo: the call of the Chinese flute elicits the response of the European willow. That this is necessarily a comparative process–between Asia and Europe, between China, France, and Germany – suggests its resonance as an example of the West-Eastern lyric