Explosions of xenon clusters in ultraintense femtosecond x-ray pulses from the LCLS free electron laser

Explosions of large Xe clusters (<N> ~ 11,000) irradiated by femtosecond pulses of 850 eV x-ray photons focused to an intensity of up to 10(17) W/cm(2) from the Linac Coherent Light Source were investigated experimentally. Measurements of ion charge-state distributions and energy spectra exhibit strong evidence for the formation of a Xe nanoplasma in the intense x-ray pulse. This x-ray produced Xe nanoplasma is accompanied by a three-body recombination and hydrodynamic expansion. These experimental results appear to be consistent with a model in which a spherically exploding nanoplasma is formed inside the Xe cluster and where the plasma temperature is determined by photoionization heating.

Ultrafast x-ray scattering of xenon nanoparticles: imaging transient states of matter

Femtosecond x-ray laser flashes with power densities of up to 10(14) W/cm(2) at 13.7 nm wavelength were scattered by single xenon clusters in the gas phase. Similar to light scattering from atmospheric microparticles, the x-ray diffraction patterns carry information about the optical constants of the objects. However, the high flux of the x-ray laser induces severe transient changes of the electronic configuration, resulting in a tenfold increase of absorption in the developing nanoplasma. The modification in opaqueness can be correlated to strong atomic charging of the particle leading to excitation of Xe(4+). It is shown that single-shot single-particle scattering on femtosecond time scales yields insight into ultrafast processes in highly excited systems where conventional spectroscopy techniques are inherently blind.

A flexible quantitative methodology for the analysis of gene-flow between conventionally bred maize populations using microsatellite markers

Previous studies of gene-flow in agriculture have used a range of physical and biochemical markers, including transgenes. However, physical and biochemical markers are not available for all commercial varieties, and transgenes are difficult to use when trying to estimate gene flow in the field where the use of transgenes is often restricted. Here, we demonstrate the use of simple sequence repeat microsatellite markers (SSRs) to study gene flow in maize. Developing the first quantitative analysis of pooled SSR samples resulted in a high sampling efficiency which minimised the use of resources and greatly enhanced the possibility of hybrid detection. We were able to quantitatively distinguish hybrids in pools of ten samples from non-hybrid parental lines in all of the 24 pair-wise combinations of commercial varieties tested. The technique was used to determine gene flow in field studies, from which a simple model describing gene flow in maize was developed.

Accumulation of chlorophyll catabolites photosensitizes the hypersensitive response elicited by Pseudomonas syringae in Arabidopsis

• The staygreen (SGR) gene encodes a chloroplast-targeted protein which promotes chlorophyll degradation via disruption of light-harvesting complexes (LHCs). • Over-expression of SGR in Arabidopsis (SGR-OX) in a Columbia-0 (Col-0) background caused spontaneous necrotic flecking. To relate this to the hypersensitive response (HR), Col-0, SGR-OX and RNAi SGR (SGRi) lines were challenged with Pseudomonas syringae pv tomato (Pst) encoding the avirulence gene avrRpm1. Increased and decreased SGR expression, respectively, accelerated and suppressed the kinetics of HR-cell death. In Col-0, SGR transcript increased at 6  h after inoculation (hai) when tissue electrolyte leakage indicated the initiation of cell death. • Excitation of the chlorophyll catabolite pheophorbide (Pheide) leads to the formation of toxic singlet oxygen ((1)O(2)). Pheide was first detected at 6  hai with Pst avrRpm1 and was linked to (1)O(2) generation and correlated with reduced Pheide a oxygenase (PaO) protein concentrations. The maximum quantum efficiency of photosystem II (F(v)/F(m)), quantum yield of electron transfer at photosystem II (φPSII), and photochemical quenching (qP) decreased at 6  hai in Col-0 but not in SGRi. Disruption of photosynthetic electron flow will cause light-dependent H(2)O(2) generation at 6  hai. • We conclude that disruption of LHCs, possibly influenced by SGR, and absence of PaO produce phototoxic chlorophyll catabolites and oxidative stress leading to the HR.

Catabolites of chlorophyll in senescing barley leaves are localized in the vacuoles of mesophyll cells

Senescing barley leaves accumulate a series of pink pigments with the chemical properties of catabolites derived from chlorophyll. Levels of the major component of this group of pigments were quantified by HPLC and shown to be maximal in tissues exhibiting maximal rates of chlorophyll degradation. Protoplasts were isolated from senescent leaf tissue and fractionated to yield intact vacuoles and plastids. Although small but significant proportions both of total catabolites and of the dominant component of the series were recovered from the plastid fraction, the vast bulk of these compounds could be assigned to the vacuole. These observations suggest a role for the vacuole in the later stages of chlorophyll breakdown during senescence.

Liver failure at the front door

Patients with ALF or ACLF frequently develop multiple organ failure and should be managed by senior physicians in a high dependency or intensive care environment (Table 4).

[Transradial approach for interventional cardiology in women]

The treatment of cardiovascular disease has considerably evolved over the past 20 years, resulting in a reduction in cardiovascular mortality among the general population. Such improvement in patient outcome may be partly attributed to interventional cardiology procedures. However, these encouraging results are not uniformly observed in men and women and the rate of cardiovascular mortality in female patients remains unchanged. A number of studies have shown a poorer outcome in women with coronary artery disease undergoing percutaneous coronary intervention. Several reasons may explain the difference in post-PCI outcome between men and women. More advanced age and higher percentage of diabetics are documented clinical factors. Other angiographic factors such as vessel size, smaller in the female population, may also account for such a difference. Finally, the occurrence of vascular complications is one of the reasons affecting the outcome of female patients. The radial vascular approach contributes to the reduction in the incidence of complications which may compromise survival. This vascular route may be more complex in the female population because of the size of the radial artery which is smaller than in men. Nevertheless, the transradial approach is very safe and efficient in experienced hands and it is probably one of the techniques which may help close the prognosis gap between men and women undergoing PCI.

Business schools and management research: a UK perspective

Purpose

In recent years, the role and value of management research is being increasingly challenged because of the perceived imbalance between its rigour and relevance. The purpose of this paper is to review the progress of management research in the UK and focuses particularly on the need for sensible evaluation of the impact of management research.

Design/methodology/approach

The paper outlines the research challenges faced by business schools from a UK perspective. It draws upon the author's experiences and the results of an analytic study of Economic and Social Research Council‐sponsored research undertaken by the author in 2008.

Findings

There is a perception that management as a discipline, and its resulting research profile, may be more difficult to evaluate than its social science sub‐disciplines such as economics, psychology, and sociology. In some instances, management research is perceived as of lower quality and capacity shortages of high‐quality management research scholars have also been identified. The dominant research challenges are both to successfully design practice‐informed management scholarship and to carefully address the dissemination of results in order to influence the impact of management research on practice.

Originality/value

The paper suggests that an increasing focus on practice and cross‐cutting inter‐disciplinary topics, such as climate change or the role of finance in society, should form a significant element of the research agendas of business schools. In any event, it is argued that cutting‐edge research should be the overarching aim of business schools in a knowledge society.

Evolution of plant senescence

BACKGROUND

Senescence is integral to the flowering plant life-cycle. Senescence-like processes occur also in non-angiosperm land plants, algae and photosynthetic prokaryotes. Increasing numbers of genes have been assigned functions in the regulation and execution of angiosperm senescence. At the same time there has been a large expansion in the number and taxonomic spread of plant sequences in the genome databases. The present paper uses these resources to make a study of the evolutionary origins of angiosperm senescence based on a survey of the distribution, across plant and microbial taxa, and expression of senescence-related genes.

RESULTS

Phylogeny analyses were carried out on protein sequences corresponding to genes with demonstrated functions in angiosperm senescence. They include proteins involved in chlorophyll catabolism and its control, homeoprotein transcription factors, metabolite transporters, enzymes and regulators of carotenoid metabolism and of anthocyanin biosynthesis. Evolutionary timelines for the origins and functions of particular genes were inferred from the taxonomic distribution of sequences homologous to those of angiosperm senescence-related proteins. Turnover of the light energy transduction apparatus is the most ancient element in the senescence syndrome. By contrast, the association of phenylpropanoid metabolism with senescence, and integration of senescence with development and adaptation mediated by transcription factors, are relatively recent innovations of land plants. An extended range of senescence-related genes of Arabidopsis was profiled for coexpression patterns and developmental relationships and revealed a clear carotenoid metabolism grouping, coordinated expression of genes for anthocyanin and flavonoid enzymes and regulators and a cluster pattern of genes for chlorophyll catabolism consistent with functional and evolutionary features of the pathway.

CONCLUSION

The expression and phylogenetic characteristics of senescence-related genes allow a framework to be constructed of decisive events in the evolution of the senescence syndrome of modern land-plants. Combining phylogenetic, comparative sequence, gene expression and morphogenetic information leads to the conclusion that biochemical, cellular, integrative and adaptive systems were progressively added to the ancient primary core process of senescence as the evolving plant encountered new environmental and developmental contexts.