Hydrodynamics of polar liquid crystals

Starting from a microscopic definition of an alignment vector proportional to the polarization, we discuss the hydrodynamics of polar liquid crystals with local $C_{\infty v}$-symmetry. The free energy for polar liquid crystals differs from that of nematic liquid crystals ($D_{\infty h}$) in that it contains terms violating the ${\bf{n}}\to -{\bf{n}}$ symmetry. First we show that these $\mathcal{Z}_2$-odd terms induce a general splay instability of a uniform polarized state in a range of parameters. Next we use the general Poisson-bracket formalism to derive the hydrodynamic equations of the system in the polarized state. The structure of the linear hydrodynamic modes confirms the existence of the splay instability.Comment: 9 pages, corrected typos, added references, revised content, to appear in PR

Experimental Designs for Binary Data in Switching Measurements on Superconducting Josephson Junctions

We study the optimal design of switching measurements of small Josephson junction circuits which operate in the macroscopic quantum tunnelling regime. Starting from the D-optimality criterion we derive the optimal design for the estimation of the unknown parameters of the underlying Gumbel type distribution. As a practical method for the measurements, we propose a sequential design that combines heuristic search for initial estimates and maximum likelihood estimation. The presented design has immediate applications in the area of superconducting electronics implying faster data acquisition. The presented experimental results confirm the usefulness of the method. KEY WORDS: optimal design, D-optimality, logistic regression, complementary log-log link, quantum physics, escape measurement

Economic performance or electoral necessity? Evaluating the system of voluntary income to political parties

Whilst the public funding of political parties is the norm in western democracies, its comprehensive introduction has been resisted in Britain. Political and electoral arrangements in Britain require parties to function and campaign on a regular basis, whilst their income follows cycles largely related to general elections. This article shows that the best predictor of party income is the necessity of a well-funded general election campaign rather than party performance. As a result, income can only be controlled by parties to a limited degree, which jeopardises their ability to determine their own financial position and fulfil their functions as political parties

Union renewal in historical perspective

This article revisits contemporary union renewal/revival debates through comparison with the late 1930s resurgence of trade unionism in the UK’s engineering industry. It is argued that the 1930s union renewal arose from more favourable contextual conditions than those currently obtaining. It was led by political activists, with better-articulated organisation and greater resonance in the working class than their contemporary counterparts, and who were assisted by state policy and pro-worker forces. Conclusions are drawn in relation to current debates

Different expressions of the same mode: a recent dialogue between archaeological and contemporary drawing practices

In this article we explore what we perceive as pertinent features of shared experience at the excavations of an Iron Age Hillfort at Bodfari, North Wales, referencing artist, archaeologist and examples of seminal art works and archaeological records resulting through inter-disciplinary collaboration. We explore ways along which archaeological and artistic practices of improvisation become entangled and productive through their different modes of mark-making. We contend that marks and memories of artist and archaeologist alike emerge interactively, through the mutually constituting effects of the object of study, the tools of exploration, and the practitioners themselves, when they are enmeshed in the cross-modally bound activities. These include, but are not limited to, remote sensing, surveying, mattocking, trowelling, drawing, photographing, videoing and sound recording. These marks represent the co-signatories: the gesture of the often anonymous practitioners, the voice of the deposits, as well as the imprint of the tools, and their interplay creates a multi-threaded narrative documenting their modes of intra-action, in short our practices. They occupy the conceptual space of paradata, and in the process of saturating the interstices of digital cognitive prosthetics they lend probity to their translations in both art form and archive

Unsatisfactory gene transfer into bone-resorbing osteoclasts with liposomal transfection systems

BACKGROUND: Bone-resorbing osteoclasts are multinucleated cells that are formed via fusion of their hematopoietic stem cells. Many of the details of osteoclast formation, activation and motility remain unsolved. Therefore, there is an interest among bone biologists to transfect the terminally differentiated osteoclasts and follow their responses to the transgenes in vitro. Severe difficulties in transfecting the large, adherent osteoclasts have been encountered, however, making the use of modern cell biology tools in osteoclast research challenging. Transfection of mature osteoclasts by non-viral gene transfer systems has not been reported. RESULTS: We have systematically screened the usefulness of several commercial DNA transfection systems in human osteoclasts and their mononuclear precursor cell cultures, and compared transfection efficacy to adenoviral DNA transfection. None of the liposome-based or endosome disruption-inducing systems could induce EGFP-actin expression in terminally differentiated osteoclasts. Instead, a massive cell death by apoptosis was found with all concentrations and liposome/DNA-ratios tested. Best transfection efficiencies were obtained by adenoviral gene delivery. Marginal DNA transfection was obtained by just adding the DNA to the cell culture medium. When bone marrow-derived CD34-positive precursor cells were transfected, some GFP-expression was found at the latest 24 h after transfection. Large numbers of apoptotic cells were found and those cells that remained alive, failed to form osteoclasts when cultured in the presence of RANKL and M-CSF, key regulators of osteoclast formation. In comparison, adenoviral gene delivery resulted in the transfection of CD34-positive cells that remained GFP-positive for up to 5 days and allowed osteoclast formation. CONCLUSION: Osteoclasts and their precursors are sensitive to liposomal transfection systems, which induce osteoclast apoptosis. Gene transfer to mononuclear osteoclast precursors or differentiated osteoclasts was not possible with any of the commercial transfection systems tested. Osteoclasts are non-dividing, adherent cells that are difficult to grow as confluent cultures, which may explain problems with transfection reagents. Large numbers of α(v)β(3 )integrin on the osteoclast surface allows adenovirus endocytosis and infection proceeds in dividing and non-dividing cells efficiently. Viral gene delivery is therefore currently the method of choice for osteoclast transfection

Fact and fiction in housing research: utilizing the creative imagination

As much of our conceptual framework is informed by the experience of the imagination, there is much to be learnt from a study of various creative forms. Narrative fiction can be one such form, allowing us to gain a useful insight into complex features of social life. The purpose of this article is to investigate the treatment of housing issues in contemporary literature in order to gain insights into attitudes, experiences and interpretations from the perspective of a broad cultural milieu. Discussions of professionalism, housing tenure and homelessness have tended to be conducted within a narrow framework and adopted orthodox modes of evaluation. Consequently, the neglect of housing within a wider cultural context has reinforced the isolation of housing issues. The article argues that although discussions of housing and housing policy have been seriously limited within the contemporary novel, there are a number of key insights that can be gained from a discussion of issues within a fictional setting

Connexin-mimetic peptide Gap 27 decreases osteoclastic activity

BACKGROUND: Bone remodelling is dependent on the balance between bone resorbing osteoclasts and bone forming osteoblasts. We have shown previously that osteoclasts contain gap-junctional protein connexin-43 and that a commonly used gap-junctional inhibitor, heptanol, can inhibit osteoclastic bone resorption. Since heptanol may also have some unspecific effect unrelated to gap-junctional inhibition we wanted to test the importance of gap-junctional communication to osteoclasts using a more specific inhibitor. METHODS: A synthetic connexin-mimetic peptide, Gap 27, was used to evaluate the contribution of gap-junctional communication to osteoclastic bone resorption. We utilised the well-characterised pit-formation assay to study the effects of the specific gap-junctional inhibitor to the survival and activity of osteoclasts. RESULTS: Gap 27 caused a remarked decrease in the number of both TRAP-positive mononuclear and multinucleated rat osteoclasts cultured on bovine bone slices. The decrease in the cell survival seemed to be restricted to TRAP-positive cells, whereas the other cells of the culture model seemed unaffected. The activity of the remaining osteoclasts was found to be diminished by measuring the percentage of osteoclasts with actin rings of all TRAP-positive cells. In addition, the resorbed area in the treated cultures was greatly diminished. CONCLUSIONS: On the basis of these results we conclude that gap-junctional communication is essential for the action of bone resorbing osteoclasts and for proper remodelling for bone

Structural Conformers of (1,3-Dithiol-2-ylidene)ethanethioamides: The Balance Between Thioamide Rotation and Preservation of Classical Sulfur-Sulfur Hypervalent Bonds

The reaction of N-(2-phthalimidoethyl)-N-alkylisopropylamines and S2Cl2 gave 4-N-(2-phthalimidoethyl)-N-alkylamino-5-chloro-1,2-dithiol-3-thiones that quantitatively cycloadded to dimethyl or diethyl acetylenedicarboxylate to give stable thioacid chlorides, which in turn reacted with one equivalent of aniline or a thiole to give thioanilides or a dithioester. Several compounds of this series showed atropisomers that were studied by a combination of dynamic NMR, simulation of the signals, conformational analysis by DFT methods, and single crystal X-ray diffraction, showing a good correlation between the theoretical calculations, the experimental values of energies, and the preferred conformations in the solid state. The steric hindering of the crowded substitution at the central amine group was found to be the reason for the presence of permanent atropisomers in this series of compounds and the cause of a unique disposition of the thioxo group at close-to-right angles with respect to the plane defined by the 1,3-dithiole ring in the dithiafulvene derivatives, thus breaking the sulfur–sulfur hypervalent bond that is always found in this kind of compounds.Ministerio de Economıá y Competitividad, Spain (Project CTQ2012- 31611), Junta de Castilla y León, Consejería de Educación y Cultura y Fondo Social Europeo (Project BU246A12-1), and the European Commission, Seventh Framework Programme (Project SNIFFER FP7-SEC-2012-312411