Multiphoton ionization and stabilization of helium in superintense xuv fields

Multiphoton ionization of helium is investigated in the superintense field regime, with particular emphasis on the role of the electron-electron interaction in the ionization and stabilization dynamics. To accomplish this, we solve ab initio the time-dependent Schr\"odinger equation with the full electron-electron interaction included. By comparing the ionization yields obtained from the full calculations with corresponding results of an independent-electron model, we come to the somewhat counterintuitive conclusion that the single-particle picture breaks down at superstrong field strengths. We explain this finding from the perspective of the so-called Kramers-Henneberger frame, the reference frame of a free (classical) electron moving in the field. The breakdown is tied to the fact that shake-up and shake-off processes cannot be properly accounted for in commonly used independent-electron models. In addition, we see evidence of a change from the multiphoton to the shake-off ionization regime in the energy distributions of the electrons. From the angular distribution it is apparent that correlation is an important factor even in this regime

A DFT+U study of the structural, electronic, magnetic, and mechanical properties of cubic and orthorhombic SmCoO3

SmCoO3 is a perovskite material that has gained attention as a potential substitute for La1−xSrxMnO3−d as a solid oxide fuel cell cathode. However, a number of properties have remained unknown due to the complexity of the material. For example, we know from experimental evidence that this perovskite exists in two different crystal structures, cubic and orthorhombic, and that the cobalt ion changes its spin state at high temperatures, leading to a semiconductor-to-metal transition. However, little is known about the precise magnetic structure that causes the metallic behavior or the spin state of the Co centers at high temperature. Here, we therefore present a systematic DFT+U study of the magnetic properties of SmCoO3 in order to determine what magnetic ordering is the one exhibited by the metallic phase at different temperatures. Similarly, mechanical properties are difficult to measure experimentally, which is why there is a lack of data for the two different phases of SmCoO3. Taking advantage of our DFT calculations, we have determined the mechanical properties from our calculated elastic constants, finding that both polymorphs exhibit similar ductility and brittleness, but that the cubic structure is harder than the orthorhombic phase

Local structure change evidenced by temperature-dependent elastic measurements: Case study on Bi1/2Na1/2TiO3-based lead-free relaxor piezoceramics

The temperature-dependent Young's modulus Y(T) of the lead-free piezoceramics of 0.8Bi(1/2)Na(1/2)TiO(3)-0.2Bi(1/2)K(1/2)TiO(3) (20BKT) and 0.96(0.8Bi(1/2)Na(1/2)TiO(3)-0.2Bi(1/2)K(1/2)TiO(3))-0.04 BiZn1/2Ti1/2O3 (4BZT) is measured with the impulse excitation technique and contrasted with corresponding dielectric and structural data. While the dielectric properties suggest a phase transition, the high resolution XRD patterns remain virtually unchanged from room temperature up to high temperatures, confirming no change in their long-range order. In contrast, the elastic properties indicate a broad and diffuse ferroelastic transition denoted by a minimum in Y(T). By analogy to the elastic and dielectric data of PbZrxTi1-xO3 and PLZT, it is concluded that 20BKT and 4BZT are relaxors with polar nanoregions embedded in a metrically cubic matrix. Interestingly, no indication for the freezing temperature was reflected in any of the employed measurement techniques. From the saturation of Y(T), it is suggested that the Burns temperature may be approximated as 700 degrees C. Moreover, it is found that the modification with the ternary end-member BiZn1/2Ti1/2O3 results in an increase in Young's modulus. A comparison with the Bi1/2Na1/2TiO3-BaTiO3-K0.5Na0.5NbO3 yields the same results.open0

Technical assistance, neo-colonialism or mutual trade? The experience of an Anglo/Ukrainian/Russian social work practice learning project

Since the collapse of the Soviet Union there has been a steady stream of Western consultants ready to work in Eastern Europe and Russia and share professional and academic expertise and experience. Social work, unknown as a discrete discipline or profession in the Soviet Union, has been a growth area with funding from a variety of sources to help promote East-West partnerships.Social work theory and practice emphasises critical appraisal of policy and embraces issues of power, discrimination and oppression. Social work educators should therefore be especially alert to the complex ethical questions which these kinds of collaborations raise, and adept at finding practical solutions or workable compromises. This article explores these ethical and political issues with reference to a project to develop social work practice learning in a Russian oblast' (region). The project was an ambitious partnership of British, Ukrainian and Russian educators, involving numerous Russian social work and related agencies, and four Russian universities and colleges in one oblast'. The authors use a series of vignettes to help the reader achieve insights into these East-West transactions. The article concludes with a discussion of different interpretations of these dealings, using three prisms: technical assistance, neo-colonialism and mutual trade

Integrin α11β1 is expressed in breast cancer stroma and associates with aggressive tumor phenotypes

Cancer‐associated fibroblasts are essential modifiers of the tumor microenvironment. The collagen‐binding integrin α11β1 has been proposed to be upregulated in a pro‐tumorigenic subtype of cancer‐associated fibroblasts. Here, we analyzed the expression and clinical relevance of integrin α11β1 in a large breast cancer series using a novel antibody against the human integrin α11 chain. Several novel monoclonal antibodies against the integrin α11 subunit were tested for use on formalin‐fixed paraffin‐embedded tissues, and Ab 210F4B6A4 was eventually selected to investigate the immunohistochemical expression in 392 breast cancers using whole sections. mRNA data from METABRIC and co‐expression patterns of integrin α11 in relation to αSMA and cytokeratin‐14 were also investigated. Integrin α11 was expressed to varying degrees in spindle‐shaped cells in the stroma of 99% of invasive breast carcinomas. Integrin α11 co‐localized with αSMA in stromal cells, and with αSMA and cytokeratin‐14 in breast myoepithelium. High stromal integrin α11 expression (66% of cases) was associated with aggressive breast cancer features such as high histologic grade, increased tumor cell proliferation, ER negativity, HER2 positivity, and triple‐negative phenotype, but was not associated with breast cancer specific survival at protein or mRNA levels. In conclusion, high stromal integrin α11 expression was associated with aggressive breast cancer phenotypes.publishedVersio

Stathmin expression associates with vascular and immune responses in aggressive breast cancer subgroups

Studies indicate that stathmin expression associates with PI3K activation in breast cancer, suggesting stathmin as a marker for targetable patient subgroups. Here we assessed stathmin in relation to tumour proliferation, vascular and immune responses, BRCA1 germline status, basal-like differentiation, clinico-pathologic features, and survival. Immunohistochemical staining was performed on breast cancers from two series (cohort 1, n = 187; cohort 2, n = 198), and mass spectrometry data from 24 cases and 12 breast cancer cell lines was examined for proteomic profiles. Open databases were also explored (TCGA, METABRIC, Oslo2 Landscape cohort, Cancer Cell Line Encyclopedia). High stathmin expression associated with tumour proliferation, p53 status, basal-like differentiation, BRCA1 genotype, and high-grade histology. These patterns were confirmed using mRNA data. Stathmin mRNA further associated with tumour angiogenesis, immune responses and reduced survival. By logistic regression, stathmin protein independently predicted a BRCA1 genotype (OR 10.0, p = 0.015) among ER negative tumours. Cell line analysis (Connectivity Map) implied PI3K inhibition in tumours with high stathmin. Altogether, our findings indicate that stathmin might be involved in the regulation of tumour angiogenesis and immune responses in breast cancer, in addition to tumour proliferation. Cell data point to potential effects of PI3K inhibition in tumours with high stathmin expression.publishedVersio