Slow waves caused by cuts perpendicular to a single subwavelength slit in metal

Copyright © 2007 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. This is the published version of an article published in New Journal of Physics Vol. 9, article 1. DOI: 10.1088/1367-2630/9/1/001Resonant transmission of microwaves through a subwavelength slit in a thick metal plate, into which subwavelength cuts have been made, is explored. Two orientations of the cuts, parallel and perpendicular to the long axis of the slit, are examined. The results show that the slits act as though filled with a medium with anisotropic effective relative permeability which at low mode numbers has the two values ~(1, 9.1), increasing to ~(1, 14.4) for higher mode numbers

Remarkable Zeroth-Order Resonant Transmission of Microwaves through a Single Subwavelength Metal Slit

James R. Suckling, J. Roy Sambles, and Christopher R. Lawrence, Physical Review Letters, Vol. 95, article 187407 (2005). "Copyright © 2005 by the American Physical Society."A slit in a thick metal plate that is extremely subwavelength will not transmit microwaves polarized parallel to it. It is shown here that cuts perpendicular to the slit allow parallel polarized radiation to resonantly transmit. Furthermore, a zero-order mode may be excited within the slit, the frequency of which, to first order, is independent of the plate depth. Remarkably, for this novel type of resonance, the field in the slit oscillates with a constant phase and little amplitude variation throughout the plate depth, while the resonant wavelength tends to infinity as the slit width approaches zero

Resonant transmission of microwaves through a hexagonal array of holes in a thin metal layer

Copyright © 2007 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. This is the published version of an article published in New Journal of Physics Vol. 9, article 101. DOI: 10.1088/1367-2630/9/4/101Resonant transmission of microwaves through a hexagonal array of holes in a very thin aluminium layer is studied. The array of holes, with diameter much less than the incident wavelength, leads to a strong transmission peak at a frequency just lower than the diffraction limit of the array. The results are well-modelled using a finite element package. The effect of metal depth on transmission intensity and the maximum efficiency of the hole array is also explored. Further experimental data are presented for the transmission of microwaves as a function of angle of incidence. It is shown that strong transmission occurs at frequencies just lower than the diffraction edges of the array. Incidentally, it is also shown that less than 0.01% of normally incident microwave radiation is transmitted through a continuous metal layer of thickness only 40% of the skin depth

Anaerobic digestion: a prime solution for water, energy and food nexus challenges

We solve the problem of identifying one or more optimal patterns of anaerobic digestion (AD) installation across the UK, by considering existing installations, the current feedstock potential and the project growth of the potential via population, demography and urbanization. We test several scenarios for the level of adoption of the AD operations in the community under varying amounts of feedstock supply, which may arise from change in food waste or energy crops generation via other policies and incentives. For the most resilient scales of solutions, we demonstrate for the UK the net energy production (bio-gas and electricity) from AD (and so the avoided emissions from grid energy), the mass of bio-waste processed (and avoided land-fill), and the quantum of digestate produced (as a proxy for avoided irrigation and fertilizer production). In order to simulate the AD innovation within WEF nexus we use agent based modelling (ABM) owing to its bottom-up approach and capability of modelling complex systems with relatively low level data and information

Microwaves: thin metal slits and liquid crystals

Copyright © 2004 Society of Photo-Optical Instrumentation Engineers. This paper was published in Proceedings of SPIE Volume 5618, pp. 1-14 and is made available with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.Using liquid crystals to control the propagation of microwaves is a potentially interesting technology. By incorporating small amounts of liquid crystal in thin slat metal structures through which the microwaves may resonantly pass a whole new range of voltage tuned microwave devices are becoming available. Metallic sub-wavelength slit structures at microwave frequencies have been constructed which show Fabry-Perot type resonances in very thin slits. If the dielectric in such thin slits is an aligned liquid crystal it is found possible to voltage-control the resonant frequencies. Novel selective filters and structures for microwave beam steering have been fabricated leading to a new generation of liquid crystal controlled devices

Enhanced microwave transmission through a patterned metal film

Copyright © 2007 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters 90 (2007) and may be found at http://link.aip.org/link/?APPLAB/90/223506/1Selective transmission of radiation through a two-dimensional array of subwavelength slits in an otherwise opaque thin metal film is presented at microwave frequencies. Individual slits are modified with the addition of perpendicular cuts, which interestingly and perhaps counterintuitively leads to resonant transmission when the incident radiation is polarized parallel to the slits. Finite element modeling of the structure shows the transmission of radiation polarized parallel to the slit direction to be a result of induced surface currents exciting a zeroth-order Fabry-Pérot mode

Rationalising sequence selection by ligand assemblies in the DNA minor groove : the case for thiazotropsin A

DNA-sequence and structure dependence on the formation of minor groove complexes at 5′-XCTAGY-3′ by the short lexitropsin thiazotropsin A are explored based on NMR spectroscopy, isothermal titration calorimetry (ITC), circular dichroism (CD) and qualitative molecular modeling. The structure and solution behaviour of the complexes are similar whether X = A, T, C or G and Z = T, A, I or C, CCTAGI being thermodynamically the most favoured (ΔG = -11.1 ± 0.1 kcal.mol-1). Binding site selectivity observed by NMR for ACTAGT in the presence of TCTAGA when both accessible sequences are concatenated in a 15-mer DNA duplex construct is consistent with thermodynamic parameters (ΙΔGΙACTAGT > ΙΔGΙTCTAGA) measured separately for the binding sites and with predictions from modeling studies. Steric bulk in the minor groove for Y = G causes unfavourable ligand-DNA interactions reflected in lower Gibbs free energy of binding (ΔG = -8.5 ± 0.01 kcal.mol-1). ITC and CD data establish that thiazotropsin A binds the ODNs with binding constants between 106 and 108 M-1 and reveal that binding is driven enthalpically through hydrogen bond formation and van der Waals interactions. The consequences of these findings are considered with respect to ligand self-association and the energetics responsible for driving DNA recognition by small molecule DNA minor groove binder

Dendritic cells provide a therapeutic target for synthetic small molecule analogues of the parasitic worm product, ES-62

ES-62, a glycoprotein secreted by the parasitic filarial nematode Acanthocheilonema viteae, subverts host immune responses towards anti-inflammatory phenotypes by virtue of covalently attached phosphorylcholine (PC). The PC dictates that ES-62 exhibits protection in murine models of inflammatory disease and hence a library of drug-like PC-based small molecule analogues (SMAs) was synthesised. Four sulfone-containing SMAs termed 11a, 11e, 11i and 12b were found to reduce mouse bone marrow-derived dendritic cell (DC) pathogen-associated molecular pattern (PAMP)-induced pro-inflammatory cytokine production, inhibit NF-κB p65 activation, and suppress LPS-induced up-regulation of CD40 and CD86. Active SMAs also resulted in a DC phenotype that exhibited reduced capacity to prime antigen (Ag)-specific IFN-γ production during co-culture with naïve transgenic TCR DO.11.10 T cells in vitro and reduced their ability, following adoptive transfer, to prime the expansion of Ag-specific T lymphocytes, specifically TH17 cells, in vivo. Consistent with this, mice receiving DCs treated with SMAs exhibited significantly reduced severity of collagen-induced arthritis and this was accompanied by a significant reduction in IL-17+ cells in the draining lymph nodes. Collectively, these studies indicate that drug-like compounds that target DCs can be designed from parasitic worm products and demonstrate the potential for ES-62 SMA-based DC therapy in inflammatory disease

Consistency and interpretation of changes in millimeter-scale cortical intrinsic curvature across three independent datasets in schizophrenia.

Several studies have sought to test the neurodevelopmental hypothesis of schizophrenia through analysis of cortical gyrification. However, to date, results have been inconsistent. A possible reason for this is that gyrification measures at the centimeter scale may be insensitive to subtle morphological changes at smaller scales. The lack of consistency in such studies may impede further interpretation of cortical morphology as an aid to understanding the etiology of schizophrenia. In this study we developed a new approach, examining whether millimeter-scale measures of cortical curvature are sensitive to changes in fundamental geometric properties of the cortical surface in schizophrenia. We determined and compared millimeter-scale and centimeter-scale curvature in three separate case-control studies; specifically two adult groups and one adolescent group. The datasets were of different sizes, with different ages and gender-spreads. The results clearly show that millimeter-scale intrinsic curvature measures were more robust and consistent in identifying reduced gyrification in patients across all three datasets. To further interpret this finding we quantified the ratio of expansion in the upper and lower cortical layers. The results suggest that reduced gyrification in schizophrenia is driven by a reduction in the expansion of upper cortical layers. This may plausibly be related to a reduction in short-range connectivity

Radulescu: the other spectralist

Rădulescu is often marginalised in discussion of the early spectral composers in contrast to the Parisian 'mainstream' of (in particular) Murail and Grisey. Furthermore, his music and thought are often placed as a somewhat 'mystical' antithesis to that of Grisey. However, despite the dissimilarity on the surface of the music, the underlying principles by which Rădulescu's musical style was built are in many respects identical to those of the mainstream spectral ideal. This paper unpicks some of Rădulescu's theoretical works to demonstrate the commonality of thought with Murail and Grisey, and suggests reasons for their sounding divergence.  There follows a detailed analysis of Rădulescu's solo viola piece Das Andere, Op. 49 (1983), placed in comparison with Grisey's Prologue (1976)