Geometry and symmetries of multi-particle systems

The quantum dynamical evolution of atomic and molecular aggregates, from their compact to their fragmented states, is parametrized by a single collective radial parameter. Treating all the remaining particle coordinates in d dimensions democratically, as a set of angles orthogonal to this collective radius or by equivalent variables, bypasses all independent-particle approximations. The invariance of the total kinetic energy under arbitrary d-dimensional transformations which preserve the radial parameter gives rise to novel quantum numbers and ladder operators interconnecting its eigenstates at each value of the radial parameter. We develop the systematics and technology of this approach, introducing the relevant mathematics tutorially, by analogy to the familiar theory of angular momentum in three dimensions. The angular basis functions so obtained are treated in a manifestly coordinate-free manner, thus serving as a flexible generalized basis for carrying out detailed studies of wavefunction evolution in multi-particle systems.Comment: 37 pages, 2 eps figure

New Records of Thecacineta cothurnioides and Trematosoma rotunda (Ciliophora, Suctorea) as epibionts on nematodes from the Indian Ocean

This article deals with the report of two suctorian ciliates species viz. Thecacineta cothurnioides Collin, 1909 and Trematosoma rotunda (Allgén, 1952 ) as epibionts on Tricoma sp. and Pseudochromadora sp. (Nematoda) respectively from Ratnagiri, west coast of India, Arabian Sea (Indian Ocean). Redescription of two species with distribution and nomenclatural notes are given. Both species are recorded here first time from Indian coast and the Indian Ocean. Genus Tricoma Cobb, 1894 is also recorded here first time as a host of Th. cothurnioides

Methane in the atmosphere of the transiting hot Neptune GJ436b?

We present an analysis of seven primary transit observations of the hot Neptune GJ436b at 3.6, 4.5 and $8~\mu$m obtained with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. After correcting for systematic effects, we fitted the light curves using the Markov Chain Monte Carlo technique. Combining these new data with the EPOXI, HST and ground-based $V, I, H$ and $K_s$ published observations, the range $0.5-10~\mu$m can be covered. Due to the low level of activity of GJ436, the effect of starspots on the combination of transits at different epochs is negligible at the accuracy of the dataset. Representative climate models were calculated by using a three-dimensional, pseudo-spectral general circulation model with idealised thermal forcing. Simulated transit spectra of GJ436b were generated using line-by-line radiative transfer models including the opacities of the molecular species expected to be present in such a planetary atmosphere. A new, ab-initio calculated, linelist for hot ammonia has been used for the first time. The photometric data observed at multiple wavelengths can be interpreted with methane being the dominant absorption after molecular hydrogen, possibly with minor contributions from ammonia, water and other molecules. No clear evidence of carbon monoxide and dioxide is found from transit photometry. We discuss this result in the light of a recent paper where photochemical disequilibrium is hypothesised to interpret secondary transit photometric data. We show that the emission photometric data are not incompatible with the presence of abundant methane, but further spectroscopic data are desirable to confirm this scenario.Comment: 19 pages, 10 figures, 1 table, Astrophysical Journal in pres

Haloes and Clustering in Light, Neutron-Rich Nuclei

Clustering is a relatively widespread phenomena which takes on many guises across the nuclear landscape. Selected topics concerning the study of halo systems and clustering in light, neutron-rich nuclei are discussed here through illustrative examples taken from the Be isotopic chain.Comment: 5 pages, 5 figures Extended version of written contribution of invited talk to ENAM200

Dynamics of ion cloud in a linear Paul trap

A linear ion trap setup has been developed for studying the dynamics of trapped ion cloud and thereby realizing possible systematics of a high precision measurement on a single ion within it. The dynamics of molecular nitrogen ion cloud has been investigated to extract the characteristics of the trap setup. The stability of trap operation has been studied with observation of narrow nonlinear resonances pointing out the region of instabilities within the broad stability region. The secular frequency has been measured and the motional spectra of trapped ion oscillation have been obtained by using electric dipole excitation. It is applied to study the space charge effect and the axial coupling in the radial plane.Comment: Colloquium paper, 9 pages, 6 figure

Exoplanet Transmission Spectroscopy using KMOS

KMOS (K-Band Multi Object Spectrograph) is a novel integral field spectrograph installed in the VLT's ANTU unit. The instrument offers an ability to observe 24 2.8"$\times$2.8" sub-fields positionable within a 7.2' patrol field, each sub-field producing a spectrum with a 14$\times$14-pixel spatial resolution. The main science drivers for KMOS are the study of galaxies, star formation, and molecular clouds, but its ability to simultaneously measure spectra of multiple stars makes KMOS an interesting instrument for exoplanet atmosphere characterization via transmission spectroscopy. We set to test whether transmission spectroscopy is practical with KMOS, and what are the conditions required to achieve the photometric precision needed, based on observations of a partial transit of WASP-19b, and full transits of GJ 1214b and HD 209458b. Our analysis uses the simultaneously observed comparison stars to reduce the effects from instrumental and atmospheric sources, and Gaussian processes to model the residual systematics. We show that KMOS can, in theory, deliver the photometric precision required for transmission spectroscopy. However, this is shown to require a) pre-imaging to ensure accurate centering and b) a very stable night with optimal observing conditions (seeing $\sim$0.8"). Combining these two factors with the need to observe several transits, each with a sufficient out-of-transit baseline (and with the fact that similar or better precision can be reached with telescopes and instruments with smaller pressure,) we conclude that transmission spectroscopy is not the optimal science case to take advantage of the abilities offered by KMOS and VLT.Comment: 11 pages, accepted to MNRA

Measuring Plant Genetic Diversity Using Inter-Simple Sequence Repeats (ISSRS)

Simple sequence repeats (SSRs) have great utility as they are conserved and present in all eukaryotic genomes. Here we report the use of a simple PCR with fluorescently-labelled primers to amplify inter-SSR markers (ISSRs) for diversity assessments. The use of ISSR markers does not rely upon specific genetic sequence information, or prolonged method development and may be measured rapidly using the automated equipment. The major restriction of the ISSR method is at the analysis stage, as the markers are dominant it is not possible to distinguish heterozygotes as loci. We obtained ISSR data from ca. 60 phenotypically characterised Capsella bursa pastoris L. Medic (shepherds purse)accessions that had been isolated from a diverse mix of arable field sites throughout the UK. We developed mathematical scripts for use with the free statistical software tool R (http://www.rproject.org/), that processed the molecular data in a binary format to estimate genetic diversity (using the Jaccard co-efficient), and that related genotype to the plant phenotypic and environmental (site specific) traits. The methodology established has the power to predict the relationship between environmental and plant morphological characteristics