University of Bath

About: University of Bath is a education organization based out in Bath, Bath and North East Somerset, United Kingdom. It is known for research contribution in the topics: Population & Photonic-crystal fiber. The organization has 15830 authors who have published 39608 publications receiving 1358769 citations. The organization is also known as: Bath University.

Lattice dynamics and vibrational spectra of the orthorhombic, tetragonal, and cubic phases of methylammonium lead iodide

Abstract: The hybrid halide perovskite ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}{\mathrm{PbI}}_{3}$ exhibits a complex structural behavior, with successive transitions between orthorhombic, tetragonal, and cubic polymorphs around 165 and 327 K. Herein we report first-principles lattice dynamics (phonon spectrum) for each phase of ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}{\mathrm{PbI}}_{3}$. The equilibrium structures compare well to solutions of temperature-dependent powder neutron diffraction. By following the normal modes, we calculate infrared and Raman intensities of the vibrations, and compare them to the measurement of a single crystal where the Raman laser is controlled to avoid degradation of the sample. Despite a clear separation in energy between low-frequency modes associated with the inorganic (${\mathrm{PbI}}_{3}{}^{\ensuremath{-}}{)}_{n}$ network and high-frequency modes of the organic ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}{}^{+}$ cation, significant coupling between them is found, which emphasizes the interplay between molecular orientation and the corner-sharing octahedral networks in the structural transformations. Soft modes are found at the boundary of the Brillouin zone of the cubic phase, consistent with displacive instabilities and anharmonicity involving tilting of the ${\mathrm{PbI}}_{6}$ octahedra around room temperature.

MEK1 and MEK2 inhibitors and cancer therapy: the long and winding road.

Abstract: The role of the ERK signalling pathway in cancer is thought to be most prominent in tumours in which mutations in the receptor tyrosine kinases RAS, BRAF, CRAF, MEK1 or MEK2 drive growth factor-independent ERK1 and ERK2 activation and thence inappropriate cell proliferation and survival. New drugs that inhibit RAF or MEK1 and MEK2 have recently been approved or are currently undergoing late-stage clinical evaluation. In this Review, we consider the ERK pathway, focusing particularly on the role of MEK1 and MEK2, the 'gatekeepers' of ERK1/2 activity. We discuss their validation as drug targets, the merits of targeting MEK1 and MEK2 versus BRAF and the mechanisms of action of different inhibitors of MEK1 and MEK2. We also consider how some of the systems-level properties (intrapathway regulatory loops and wider signalling network connections) of the ERK pathway present a challenge for the success of MEK1 and MEK2 inhibitors, discuss mechanisms of resistance to these inhibitors, and review their clinical progress.

A Narrative Approach to Collective Identities

Abstract: From a narrative perspective, organizations' identities are discursive (linguistic) constructs constituted by the multiple identity-relevant narratives that their participants author about them, and which feature, for example, in documents, conversations and electronic media. By defining collective identities as the totality of such narratives I draw attention to their complex, and often fragmented and heterogeneous nature. My approach contrasts with much of the theorizing in this field which has tended to homogenize collective identities by emphasizing what is common or shared, failed to capture the interplay between different communities within organizations, and produced bland, undifferentiated empirical research. In particular, the theoretical framework that I outline focuses attention on the importance of reflexivity, voice, plurivocity, temporality, and fictionality to an understanding of collective identities as locales for competing hegemonic claims. In combination, these notions form a unique conceptual model for theorizing and researching collective identities. This said, a narrative approach also has its limitations, and is proposed as an additional, not exclusive, interpretive lens.