186 research outputs found

### ITERA: IDL Tool for Emission-line Ratio Analysis

We present a new software tool to enable astronomers to easily compare
observations of emission line ratios with those determined by photoionization
and shock models, ITERA, the IDL Tool for Emission-line Ratio Analysis. This
tool can plot ratios of emission lines predicted by models and allows for
comparison of observed line ratios against grids of these models selected from
model libraries associated with the tool. We provide details of the libraries
of standard photoionization and shock models available with ITERA, and, in
addition, present three example emission line ratio diagrams covering a range
of wavelengths to demonstrate the capabilities of ITERA. ITERA, and associated
libraries, is available from \url{http://www.brentgroves.net/itera.html}Comment: Accepted for New Astronomy, 3 figures. ITERA tool available to
download from http://www.brentgroves.net/itera.htm

### Pentaborate(1-) salts templated by substituted pyrrolidinium cations: synthesis, structural characterization, and modelling of solid-state H-bond interactions by DFT calculations

The synthesis and characterization of a series of pentaborate(1â��) salts of substituted pyrrolidinium cations [C4H8NH2][B5O6(OH)4] (1), [C4H8NMe2][B5O6(OH)4] (2) [C4H8NMeH][B5O6(OH)4] (3), [(2-CH2OH)C4H7NH2][B5O6(OH)4] (4) is reported. All compounds were characterized by single-crystal XRD studies with 3 (1/2CH3COCH3) and 4 (1/2H2O) solvated. TGA/DSC analysis of the pentaborates 1â��4 showed that they thermally decomposed in air at 800 Â°C to 2.5 B2O3, in a 2 step process involving dehydration (<250 Â°C) and oxidative decomposition (250â��600 Â°C). BET analysis of materials derived thermally from the pentaborates 1 and 2 had internal porosities of <1 m2 gâ��1, indicating they were non-porous. All compounds show extensive supramolecular H-bonded anionic lattices. H-bond interactions are described in detail and motifs found in these and in other pentaborate structures have been examined and modelled by DFT calculations. These calculations confirm that H-bonds interactions in pentaborates are moderately strong (ca. â��10 to â��21 kJ molâ��1) and are likely to dominate the energetics of their templated syntheses

### Temperature and Polarization Patterns in Anisotropic Cosmologies

We study the coherent temperature and polarization patterns produced in
homogeneous but anisotropic cosmological models. We show results for all
Bianchi types with a Friedman-Robertson-Walker limit (i.e. Types I, V,
VII$_{0}$, VII$_{h}$ and IX) to illustrate the range of possible behaviour. We
discuss the role of spatial curvature, shear and rotation in the geodesic
equations for each model and establish some basic results concerning the
symmetries of the patterns produced. We also give examples of the
time-evolution of these patterns in terms of the Stokes parameters $I$, $Q$ and
$U$.Comment: 24 pages, 7 Figures, submitted to JCAP. Revised version: numerous
references added, text rewritten, and errors corrected

### A complete solution of a Constrained System: SUSY Monopole Quantum Mechanics

We solve the quantum mechanical problem of a charged particle on S^2 in the
background of a magnetic monopole for both bosonic and supersymmetric cases by
constructing Hilbert space and realizing the fundamental operators obeying
complicated Dirac bracket relations in terms of differential operators. We find
the complete energy eigenfunctions. Using the lowest energy eigenstates we
count the number of degeneracies and examine the supersymmetric structure of
the ground states in detail.Comment: 20 pages including the title, prepared in JHEP forma

### Superconformal Multi-Black Hole Moduli Spaces in Four Dimensions

Quantum mechanics on the moduli space of N supersymmetric Reissner-Nordstrom
black holes is shown to admit 4 supersymmetries using an unconventional
supermultiplet which contains 3N bosons and 4N fermions. A near-horizon limit
is found in which the quantum mechanics of widely separated black holes
decouples from that of strongly-interacting, near-coincident black holes. This
near-horizon theory is shown to have an enhanced D(2,1;0) superconformal
symmetry. The bosonic symmetries are SL(2,R) conformal symmetry and SU(2)xSU(2)
R-symmetry arising from spatial rotations and the R-symmetry of N=2
supergravity.Comment: 23 pages, harvmac. v2: many typos fixe

### Classification of irreps and invariants of the N-extended Supersymmetric Quantum Mechanics

We present an algorithmic classification of the irreps of the $N$-extended
one-dimensional supersymmetry algebra linearly realized on a finite number of
fields. Our work is based on the 1-to-1 \cite{pt} correspondence between
Weyl-type Clifford algebras (whose irreps are fully classified) and classes of
irreps of the $N$-extended 1D supersymmetry. The complete classification of
irreps is presented up to $N\leq 10$. The fields of an irrep are accommodated
in $l$ different spin states. N=10 is the minimal value admitting length $l>4$
irreps. The classification of length-4 irreps of the N=12 and {\em real} N=11
extended supersymmetries is also explicitly presented.\par Tensoring irreps
allows us to systematically construct manifestly ($N$-extended) supersymmetric
multi-linear invariants {\em without} introducing a superspace formalism.
Multi-linear invariants can be constructed both for {\em unconstrained} and
{\em multi-linearly constrained} fields. A whole class of off-shell invariant
actions are produced in association with each irreducible representation. The
explicit example of the N=8 off-shell action of the $(1,8,7)$ multiplet is
presented.\par Tensoring zero-energy irreps leads us to the notion of the {\em
fusion algebra} of the 1D $N$-extended supersymmetric vacua.Comment: Final version to appear in JHEP. 52 pages. The part with the complete
classification of irreps (and the explicit presentation of length-4 irreps of
N=9,10,11,12 and N=10 length-5 irreps) is unchanged. An extra section has
been added with an entire class of off-shell invariant actions for arbitrary
values N of the 1D extended supersymmetry. A non-trivial N=8 off-shell action
for the (1,8,7) multiplet has been constructed as an example. It is obtained
in terms of the octonionic structure constant

### A Nanophotonic Structure Containing Living Photosynthetic Bacteria

Photosynthetic organisms rely on a series of self-assembled nanostructures with tuned electronic energy levels in order to transport energy from where it is collected by photon absorption, to reaction centers where the energy is used to drive chemical reactions. In the photosynthetic bacteria Chlorobaculum tepidum, a member of the green sulfur bacteria family, light is absorbed by large antenna complexes called chlorosomes to create an exciton. The exciton is transferred to a protein baseplate attached to the chlorosome, before migrating through the Fenna-Matthews-Olson complex to the reaction center. Here, it is shown that by placing living Chlorobaculum tepidum bacteria within a photonic microcavity, the strong exciton-photon coupling regime between a confined cavity mode and exciton states of the chlorosome can be accessed, whereby a coherent exchange of energy between the bacteria and cavity mode results in the formation of polariton states. The polaritons have energy distinct from that of the exciton which can be tuned by modifying the energy of the optical modes of the microcavity. It is believed that this is the first demonstration of the modification of energy levels within living biological systems using a photonic structure

### N=4 supersymmetric Eguchi-Hanson sigma model in d=1

We show that it is possible to construct a supersymmetric mechanics with four
supercharges possessing not conformally flat target space. A general idea of
constructing such models is presented. A particular case with Eguchi--Hanson
target space is investigated in details: we present the standard and quotient
approaches to get the Eguchi--Hanson model, demonstrate their equivalence, give
a full set of nonlinear constraints, study their properties and give an
explicit expression for the target space metric.Comment: LaTeX, 9 page

### The spinorial geometry of supersymmetric heterotic string backgrounds

We determine the geometry of supersymmetric heterotic string backgrounds for
which all parallel spinors with respect to the connection $\hat\nabla$ with
torsion $H$, the NS$\otimes$NS three-form field strength, are Killing. We find
that there are two classes of such backgrounds, the null and the timelike. The
Killing spinors of the null backgrounds have stability subgroups
K\ltimes\bR^8 in $Spin(9,1)$, for $K=Spin(7)$, SU(4), $Sp(2)$, $SU(2)\times
SU(2)$ and $\{1\}$, and the Killing spinors of the timelike backgrounds have
stability subgroups $G_2$, SU(3), SU(2) and $\{1\}$. The former admit a single
null $\hat\nabla$-parallel vector field while the latter admit a timelike and
two, three, five and nine spacelike $\hat\nabla$-parallel vector fields,
respectively. The spacetime of the null backgrounds is a Lorentzian
two-parameter family of Riemannian manifolds $B$ with skew-symmetric torsion.
If the rotation of the null vector field vanishes, the holonomy of the
connection with torsion of $B$ is contained in $K$. The spacetime of time-like
backgrounds is a principal bundle $P$ with fibre a Lorentzian Lie group and
base space a suitable Riemannian manifold with skew-symmetric torsion. The
principal bundle is equipped with a connection $\lambda$ which determines the
non-horizontal part of the spacetime metric and of $H$. The curvature of
$\lambda$ takes values in an appropriate Lie algebra constructed from that of
$K$. In addition $dH$ has only horizontal components and contains the
Pontrjagin class of $P$. We have computed in all cases the Killing spinor
bilinears, expressed the fluxes in terms of the geometry and determine the
field equations that are implied by the Killing spinor equations.Comment: 73pp. v2: minor change

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