Publications by authors named "Michael R Norman"

Understanding surface collective dynamics in quantum materials is crucial for advancing quantum technologies. For example, surface phonon modes in quantum paraelectrics are thought to be essential in facilitating interfacial superconductivity. However, detecting these modes, especially below 1 terahertz, is challenging because of limited sampling volumes and the need for high spectroscopic resolution.

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Article Synopsis
  • The formation of Cooper pairs in unconventional superconductors is complex, with limited experimental evidence linking to specific mechanisms.
  • This research investigates how the superconducting transition temperature (T) varies with carrier density (n) in electron gases at different KTaO interfaces, particularly noting a strong linear relationship at the (111) interface.
  • The findings suggest that superconductivity is influenced by the interface's crystallographic orientation, with a proposed mechanism involving inter-orbital interactions and phonon effects, which could help understand pairing in other superconducting materials.
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The glucocorticoid receptor (GR) is a member of the nuclear receptor superfamily, which controls programs regulating cell proliferation, differentiation, and apoptosis. We have identified an unexpected role for GR in mitosis. We discovered that specifically modified GR species accumulate at the mitotic spindle during mitosis in a distribution that overlaps with Aurora kinases.

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The energy gap for electronic excitations is one of the most important characteristics of the superconducting state, as it directly reflects the pairing of electrons. In the copper-oxide high-temperature superconductors (HTSCs), a strongly anisotropic energy gap, which vanishes along high-symmetry directions, is a clear manifestation of the d-wave symmetry of the pairing. There is, however, a dramatic change in the form of the gap anisotropy with reduced carrier concentration (underdoping).

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The competition between proximate electronic phases produces a complex phenomenology in strongly correlated systems. In particular, fluctuations associated with periodic charge or spin modulations, known as density waves, may lead to exotic superconductivity in several correlated materials. However, density waves have been difficult to isolate in the presence of chemical disorder, and the suspected causal link between competing density wave orders and high-temperature superconductivity is not understood.

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In order to understand the origin of high-temperature superconductivity in copper oxides, we must understand the normal state from which it emerges. Here, we examine the evolution of the normal state electronic excitations with temperature and carrier concentration in Bi(2)Sr(2)CaCu(2)O(8+δ) using angle-resolved photoemission. In contrast to conventional superconductors, where there is a single temperature scale T(c) separating the normal from the superconducting state, the high-temperature superconductors exhibit two additional temperature scales.

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Glucocorticoid (GC) hormones are secreted from the adrenal gland in a characteristic pulsatile pattern. This ultradian secretory activity exhibits remarkable plasticity, with distinct changes in response to both physiological and stressful stimuli in humans and experimental animals. It is therefore important to understand how the pattern of GC exposure regulates intracellular signaling through the GC receptor (GR).

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During the past few decades, several new classes of superconductors have been discovered that do not appear to be related to traditional superconductors. The source of the superconductivity of these materials is likely different from the electron-ion interactions that are at the heart of conventional superconductivity. Developing a rigorous theory for any of these classes of materials has proven to be a difficult challenge and will remain one of the major problems in physics in the decades to come.

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SERMs act as ER agonists in bone despite their antagonistic properties in other tissues. As well as inhibiting bone remodelling, this effect may involve stimulation of osteoblast activity, in light of evidence from recent in vivo studies. However, progress in exploring this action has been hampered by a lack of accurate in vitro models.

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Although many stimuli activate extracellular signal-regulated kinases 1 and 2 (ERK1/2), the kinetics and compartmentalization of ERK1/2 signals are stimulus-dependent and dictate physiological consequences. ERKs can be inactivated by dual specificity phosphatases (DUSPs), notably the MAPK phosphatases (MKPs) and atypical DUSPs, that can both dephosphorylate and scaffold ERK1/2. Using a cell imaging model (based on knockdown of endogenous ERKs and add-back of wild-type or mutated ERK2-GFP reporters), we explored possible effects of DUSPs on responses to transient or sustained ERK2 activators (epidermal growth factor and phorbol 12,13-dibutyrate, respectively).

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Spatiotemporal aspects of ERK activation are stimulus-specific and dictate cellular consequences. They are dependent upon dual specificity phosphatases (DUSPs) that bind ERK via docking domains and can both inactivate and anchor ERK in cellular compartments. Using high throughput fluorescence microscopy in combination with a system where endogenous ERKs are removed and replaced with wild-type or mutated ERK2-green fluorescent protein (GFP), we show that ERK2 activation responses to epidermal growth factor (EGF) and protein kinase C (PKC) are transient and sustained, respectively.

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Objectives: The study investigated the role of prolactin (PRL) in modulating STAT5 and electrical activity of magnocellular neurones in the supraoptic (SO) nucleus of male rats.

Methods: Evidence of expression of STAT5 in the SO nucleus was investigated by immunocytochemical methods. Effect of blocking prolactin receptors on STAT 5 expression was investigated by Western blotting following transfection of SO neurones with a dominant negative mutant form of the PRL receptor.

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Unlabelled: The effects of 17beta-estradiol (E2) and ICI 182,780 (ICI) on activity of a BMP-6 promoter were compared in osteoblast-like and breast cancer cells transiently transfected with ERalpha. E2 but not ICI stimulated BMP-6 reporter activity in breast cancer cells, whereas the opposite was observed in osteoblast-like cells, associated with lack of AF-2 dependence of the response, and absent intranuclear localization of ERalpha, suggesting the involvement of a distinct ERalpha-dependent response mechanism in osteoblasts.

Introduction: Previous studies suggest that the tissue-selective effect of antiestrogens on bone reflects the ability of these compounds to target certain osteoblast regulatory genes.

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