Optimization of nanostructured permalloy electrodes for a lateral hybrid spin-valve structure

Ferromagnetic electrodes of a lateral semiconductor-based spin-valve structure are designed to provide a maximum of spin-polarized injection current. A single-domain state in remanence is a prerequisite obtained by nanostructuring Permalloy thin film electrodes. Three regimes of aspect ratios $m$ are identified by room temperature magnetic force microscopy: (i) high-aspect ratios of $m \ge 20$ provide the favored remanent single-domain magnetization states, (ii) medium-aspect ratios $m \sim 3$ to $m \sim 20$ yield highly remanent states with closure domains and (iii) low-aspect ratios of $m \le 3$ lead to multi-domain structures. Lateral kinks, introduced to bridge the gap between micro- and macroscale, disturb the uniform magnetization of electrodes with high- and medium-aspect ratios. However, vertical flanks help to maintain a uniformly magnetized state at the ferromagnet-semiconcuctor contact by domain wall pinning.Comment: revised version, major structural changes, figures reorganized,6 pages, 8 figures, revte

Molecular aspects of insulin resistance, cell signaling pathways and breast cancer in relation to obesity.

A growing number of clinical studies validate a relation of insulin resistance and breast cancer in obese patients. We hypothesised that high plasma insulin levels cause aberrant insulin signalling in breast epithelial cells which may be responsible for an increase in cell proliferation, indicative of potential carcinogenesis and increased cancer progression. It was of particular interest to determine any differences of high insulin concentrations in activating the phosphoinositide-3 kinase (PI-3 kinase) pathway or the mitogen-activated protein kinase (MAP kinase) pathway, the latter being linked to increased cell proliferation. We used two cell line models to investigate the carcinogenic (MCF-10A, immortalised breast epithelial cells) and cancer progression (MDA-MB-231, ER-negative breast cancer cells) potential of insulin. Insulin treatment (100 nM, 24 h) increased cell proliferation in MCF-10A cells, but had no cell proliferative effect on MDA-MB-231 cells. Additionally expression of PCNA as marker of proliferation was tested. The use of PI-3 kinase and MAP kinase specific inhibitors (Wortmannin and PD98059, respectively) demonstrated both pathways being responsible for the observed increase in cell proliferation (MCF-10A). Simultaneous treatment with both inhibitors eliminated insulin induced cell proliferation entirely. Phosphorylation of ERK1/2 was examined as specific activity measurement of MAP kinase pathway. Insulin induced higher phosphorylation levels in MCF-10A cells than in MDA-MB-231. These preliminary results suggest that insulin may initiate carcinogenesis of breast epithelial cells by increasing cell proliferation rather than increasing cancer progression of existing tumours. These effects may be mediated by insulin activating both the PI-3 kinase and the MAP kinase signalling pathways

Molecular aspects linking insulin resistance to breast cancer by activation of cell signalling pathways.

Recent findings suggest a connection between obesity and breast cancer. Obesity is linked with higher incidences of insulin resistance as part of the metabolic syndrome, resulting in chronically elevated insulin plasma levels. We examined the effect of high insulin concentrations (100 nM) on estrogen-receptor (ER) negative breast cancer cells (MDA-MB-231) and normal breast epithelial cells (MCF-10a). Treatment with high insulin concentrations increased insulin receptor (IR) phosphorylation significantly in both cell lines. Phosphorylation of protein kinase B (Akt), representative of PI3-kinase cell signalling pathway activation was increased by 101% (p=0.0112) in MDA-MB-231 cells and by 81% (p=0.0031) in MCF-10a cells after 10 min insulin treatment. Phosphorylation of extracellular regulated kinase 1/2 (ERK1/2), representative of MAP-kinase cell signalling pathway activation did not change in both cell lines after 10 min of insulin treatment. Cell proliferation did not change in MDA-MB-231 cells and increased by 75% (p=0.0067) in MCF-10a cells after 24 h insulin treatment. Cell proliferation was decreased in MDA-MB-231 cells by 15% (p=0.0083) after 1 h treatment with PD98059, a MAP-kinase inhibitor. In MCF-10a cells cell proliferation was decreased by 51% (

Derivation of the Curie-Weiss Law in Dynamical Mean-Field Theory

We present an analytic derivation of the linear temperature dependence of the inverse static susceptibility $\chi ^{-1}(T,U)\sim T-T{_{c}}(U)$ near the transition from a paramagnetic to a ferromagnetic correlated metal within the dynamical mean-field theory (DMFT) for the Hubbard model. The equations for the critical temperature and interaction strength of the transition are also determined.Comment: 5 pages, no figure

Insulin-induced gene expression changes in breast cancer cells and normal breast epithelial cells.

Obesity increases breast cancer incidence rates in postmenopausal women. Chronic high levels of insulin, present in the majority of obese and insulin resistant patients, may provide the growth promoting stimulus to explain this connection. In this work, the cancer progression and cancer initiating properties of high insulin levels were examined in breast cancer cells (MDA-MB-231) and breast epithelial cells (MCF-10a), respectively. High insulin levels (100 nM) induced differential changes in cell proliferation in the two cell lines used. Human Cancer PathwayFinder DNA Microarrays (SABiosciences) were used to examine gene expression changes after insulin treatment. High insulin levels increased expression of genes involved in cell cycle control (e.g. cyclin D1) and DNA damage repair (e.g. ATM) in MDA-MB 231 cells and in MCF-10a cells (e.g. cyclin E1, CDC25a). Expression of genes responsible for mediating apoptosis and cell senescence (e.g. APAF, BAD, bcl-X) was decreased after insulin treatment in MDA-MB 231 cells but the expression of the same group of genes did not change in MCF-10a cells. High insulin levels increased expression of genes encoding for signal transduction molecules (e.g. AKT1) and transcription factors (e.g. FOS, JUN, MYC), and of genes responsible for invasion and metastasis (e.g. MMP2) in MCF-10a cells whereas gene expression of the same groups of genes did not change or was decreased in MDA-MB 231 cells. These results suggest a role for insulin resistance in breast cancer initiation and progression, aggravating the potential of breast cancer to evade apoptosis, to metastasise and may promote carcinogenesis of healthy epithelial cells

Polarisation Independent Liquid Crystal Lenses and Contact Lenses using Embossed Reactive Mesogens

Liquid crystal lenses have promise in optical systems owing to their tunability combined with low electrical power, cost, and weight. A good example of such a system is switchable contact lenses for the correction of age‐related presbyopia. Sufficiently large phase modulation can be done using nematic liquid crystals in a meniscus lens configuration. However, the birefringent materials are inherently polarisation dependent, usually requiring orthogonal polarisations to be focussed separately. A novel method is presented for producing polarisation independent lenses based on reactive mesogens. Results are presented for a 2‐level and 3‐level diffractive Fresnel lenses, and the promise of the technique for use in refractive lenses such as contact lenses is discussed

We are Who We Cite: Bridges of Influence Between Natural Language Processing and Other Academic Fields

Natural Language Processing (NLP) is poised to substantially influence the world. However, significant progress comes hand-in-hand with substantial risks. Addressing them requires broad engagement with various fields of study. Yet, little empirical work examines the state of such engagement (past or current). In this paper, we quantify the degree of influence between 23 fields of study and NLP (on each other). We analyzed ~77k NLP papers, ~3.1m citations from NLP papers to other papers, and ~1.8m citations from other papers to NLP papers. We show that, unlike most fields, the cross-field engagement of NLP, measured by our proposed Citation Field Diversity Index (CFDI), has declined from 0.58 in 1980 to 0.31 in 2022 (an all-time low). In addition, we find that NLP has grown more insular -- citing increasingly more NLP papers and having fewer papers that act as bridges between fields. NLP citations are dominated by computer science; Less than 8% of NLP citations are to linguistics, and less than 3% are to math and psychology. These findings underscore NLP's urgent need to reflect on its engagement with various fields.Comment: Published at EMNLP 202

Polarisation Independent Liquid Crystal Lenses using Embossed Reactive Mesogens

Liquid crystal lenses have promise in optical systems owing to their tunability combined with low electrical power, cost and weight. A good example of such a system is switchable contact lenses for the correction of age‐related presbyopia. Large phase modulation can be done using nematic liquid crystals. However, the birefringent materials are inherently polarisation dependent, usually requiring orthogonal polarisations to be focused separately. A novel method is presented for producing polarisation independent lenses based on reactive mesogens

Fuzzy cellular model for on-line traffic simulation

This paper introduces a fuzzy cellular model of road traffic that was intended for on-line applications in traffic control. The presented model uses fuzzy sets theory to deal with uncertainty of both input data and simulation results. Vehicles are modelled individually, thus various classes of them can be taken into consideration. In the proposed approach, all parameters of vehicles are described by means of fuzzy numbers. The model was implemented in a simulation of vehicles queue discharge process. Changes of the queue length were analysed in this experiment and compared to the results of NaSch cellular automata model.Comment: The original publication is available at http://www.springerlink.co