'Don't make me go back': post-feminist retreatism in Doctor Who

In post-2005 Doctor Who the female companion has become a seminal figure. This article shows how closely the narratives of the companions track contemporary notions of post-feminism. In particular, companions’ departures from the programme have much in common with post-feminism’s master-theme of retreatism, whereby women retreat from their public lives to find fulfilment in marriage, home and family. The article argues that when companions leave the TARDIS, what happens next ought to embody the sense of empowerment, purpose and agency which they have gained through their adventures, whereas too often the programme’s authors have given companions ‘happy endings’ based on finding husbands and settling down

Exploiting boundary states of imperfect spin chains for high-fidelity state transfer

We study transfer of a quantum state through XX spin chains with static imperfections. We combine the two standard approaches for state transfer based on (i) modulated couplings between neighboring spins throughout the spin chain and (ii) weak coupling of the outermost spins to an unmodulated spin chain. The combined approach allows us to design spin chains with modulated couplings and localized boundary states, permitting high-fidelity state transfer in the presence of random static imperfections of the couplings. The modulated couplings are explicitly obtained from an exact algorithm using the close relation between tridiagonal matrices and orthogonal polynomials [Linear Algebr. Appl. 21, 245 (1978)]. The implemented algorithm and a graphical user interface for constructing spin chains with boundary states (spinGUIn) are provided as Supplemental Material.Comment: 7 pages, 3 figures + spinGUIn description and Matlab files iepsolve.m, spinGUIn.fig, spinGUIn.

Passive broadband full Stokes polarimeter using a Fresnel cone

Light's polarisation contains information about its source and interactions, from distant stars to biological samples. Polarimeters can recover this information, but reliance on birefringent or rotating optical elements limits their wavelength range and stability. Here we present a static, single-shot polarimeter based on a Fresnel cone - the direct spatial analogue to the popular rotating quarter-wave plate approach. We measure the average angular accuracy to be 2.9 (3.6) degrees for elliptical(linear) polarisation states across the visible spectrum, with the degree of polarisation determined to within 0.12(0.08). Our broadband full Stokes polarimeter is robust, cost-effective, and could find applications in hyper-spectral polarimetry and scanning microscopy.Comment: 6 Pages, 4 Figure

Tight focal spots using azimuthally polarised light from a Fresnel cone

When focusing a light beam at high numerical aperture, the resulting electric field profile in the focal plane depends on the transverse polarisation profile, as interference between different parts of the beam needs to be taken into account. It is well known that radial polarised light produces a longitudinal polarisation component and can be focused below the conventional diffraction limit for homogeneously polarised light, and azimuthally polarised light that carries one unit of angular momentum can achieve even tighter focal spots. This is of interest for example for enhancing resolution in scanning microscopy. There are numerous ways to generate such polarisation structures, however, setups can be expensive and usually rely on birefringent components, hence prohibiting broadband operation. We have recently demonstrated a passive, low-cost technique using a simple glass cone (Fresnel cone) to generate beams with structured polarisation. We show here that the polarisation structure generated by Fresnel cones focuses better than radial polarised light at all numerical apertures. Furthermore, we investigate in detail the application of polarised light structures for two-photon microscopy. Specifically we demonstrate a method that allows us to generate the desired polarisation structure at the back aperture of the microscope by pre-compensating any detrimental phase shifts using a combination of waveplates

Characterization of cells of amniotic fluids by immunological identification of intermediate-sized filaments: Presence of cells of different tissue origin

Antibodies against intermediate-sized filaments, of the prekeratin or vimentin type, were used to investigate the presence of these filaments by indirect immunofluorescence microscopy in cultured and non-cultured amniotic fluid cells, in frozen sections of the placenta and in isolated cells of the amniotic epithelium. Two major classes of cells can be cultured from amniotic fluids, namely cells of epithelial origin containing filaments of the prekeratin type and cells of different origin which contain filaments of the vimentin type but are negative when tested with antibodies to epidermal prekeratin. The presence of prekeratin type filaments correlates with the morphology of colonies of amniotic fluid cell cultures in vitro as classified by Hoehn et al. (1974). Cells of E-type colonies are shown to be of epithelial origin. In contrast our data indicate a different origin of almost all cells of F-type colonies and of the large majority of cells of AF-type colonies. Cells of epithelial origin and positively stained with antibodies to epidermal prekeratin are occasionally scattered in F-type colonies and in variable percentages (up to 30%) in AF-type colonies. Surprisingly, cryostat sections of the amniotic epithelium and isolated groups of amniotic cells showed positive reactions with both antibodies to vimentin and prekeratin. The possibility that amniotic cells may be different from other epithelial cells in that they contain both types of filaments simultaneously already in situ is presently under investigation

1.55-μm mode-locked quantum-dot lasers with 300 MHz frequency tuning range

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 106, 031114 (2015) and may be found at https://doi.org/10.1063/1.4906451.Passive mode-locking of two-section quantum-dot mode-locked lasers grown by metalorganic vapor phase epitaxy on InP is reported. 1250-μm long lasers exhibit a wide tuning range of 300 MHz around the fundamental mode-locking frequency of 33.48 GHz. The frequency tuning is achieved by varying the reverse bias of the saturable absorber from 0 to −2.2 V and the gain section current from 90 to 280 mA. 3 dB optical spectra width of 6–7 nm leads to ex-facet optical pulses with full-width half-maximum down to 3.7 ps. Single-section quantum-dot mode-locked lasers show 0.8 ps broad optical pulses after external fiber-based compression. Injection current tuning from 70 to 300 mA leads to 30 MHz frequency tuning.DFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, BauelementeEC/FP7/EU/264687/Postgraduate Research on Photonics as an Enabling Technology/PROPHE

An Optimal Compact Storage Scheme for Nonlinear Reactor Problems by FEM

NAhttp://archive.org/details/optimalcompactst03saliThis work shows that optimal compact storage of coefficient matrices affords a significant reduction in core storage requirements over banded storage schemes. The resulting savings enables in core finite element solutions of large systems not otherwise possible. It is shown that Gears method for the stiff system of a nonlinear reactor dynamics problem is not as efficient as Crank-Nicolson integration because of substantially greater core requirements, despite its superior tracking ability. A remedy in the form of a modified implicit version of Gears method with a significant reduction in core requirements is shown to provide the same excellent accuracy as Gears method. Comparisons between the modified Gear method and the Crank-Nicolson method show the relative advantages and disadvantages of each. Finally, it is shown that although the nonlinearity encountered in this problem can be treated directly, a linear approximation of the nonlinear term affords a substantial reduction in core requirement with a relatively small cost in accuracy