Microwave Spectral Studies on Aniline and Some Other Molecules

This thesis contains an account of microwave spectral studies aniline, propiolic acid, 2,1,3-benzoxadiazole and 2,1,3-benzothiadiazole, and glycollonitrile. All of the spectra were observed at room temperature using a conventional Stark modulation spectrometer. A brief description of the spectrometer, the method used to calculate rigid asymmetric top energy levels and the location of atoms in a molecule are given in Chapter 1. Chapters 2-5 devoted to the spectral studies on the molecules mentioned above and Chapter 6 contains details of the preparation of a number of these compounds. The microwave spectra of ten isotopic species of aniline have been observed and transitions due to molecules in the ground and a very low first excited vibrational state have been assigned. A low first excited vibrational state is characteristic of a pyrimidal configuration about the nitrogen atom and an inverting amine group. The inertial defects, and substitution co-ordinates of the amino-hydrogen atoms confirm that aniline is non-planar and an rs structure has been derived for the C-NH2 group. The co-ordinates of the ring hydrogen atoms in aniline indicate that the phenyl group is somewhat narrower and elongated compared to benzene. Three species of propiolic acid have been studied and the planar nature and cis conformation of the hydroxyl relative to the carbonyl group in this molecule are confirmed. Allowance has been made for centrifugal distortion in deriving the rotational constants, but it is impossible to derive accurate values for the centrifugal distortion constants from the measured line frequencies. The dipole moment of propiolic acid has been obtained from Stark effect measurements and lies almost parallel to the direction of the C = O bond. The spectra of the normal isotopic species of 2,1,3-benzoxadiazole and 2,1,3-benzothiadiazole have been assigned and the inertial defects indicate that these molecules are planar. Structures with considerable double bond fixation in the six membered rings are proposed for these molecules. Some preliminary conclusions about the structure of glycollonitrile are given in chapter 5. Spectra of the normal and one deuterated species (DOCH2CN) have been assigned. The inertial defects of these molecules and the substitution co-ordinates of the hydroxyl hydrogen atom show that glycollonitrile exists in the gauche form

The effect of practice and coaching on the performance in intelligence tests of boys selected for courses leading to G.C.E and for boys who just fail to be selected

The object of the inquiry was to investigate the effects of unassisted practice, and of practice accompanied by coaching, on the scores made in two intelligence tests by boys who were selected for grammar schools or for a selective modern school in which some children take G.C.E. courses. The two tests were those used in the allocation examination of the hoys concerned, and the same tests were repeated as final tests at the end of the experiment. The use of two tests was intended to minimise the effects of individual inconsistency. 170 boys effectively took part in the experiment and they formed three groups of approximately equal numbers and ability. The first group had three practice tests at weekly intervals before the final tests; the second group, in addition to working the same tests, had one hour of standardised coaching on each of the three practice tests in turn; the third group did normal school work during the three weeks preceding the final tests. The scores in the two final tests, compared with those in the same two tests in the allocation examination showed a total mean gain of 11½ pts. of I. Q. in the practice group, 17½ pts. in the coached group, and 5½ pts. in the control group. Analysis of variance showed all these gains, and the differences between them, to be highly significant. Clearly therefore, the most effective way of raising the mean score of boys in intelligence tests is by a combination of practice and coaching. After the third test there was a falling off in mean score in the practice group whereas gains continued up to the last test in the coached group. The results suggest that practice effect may be inhibited to some extent when practice is under actual selection examination conditions. There is some evidence that the effects of coaching may be relatively short-lived. Individual response to practice and coaching varied considerably and was greater in the coached groups The maximum gains in both groups tended to occur at (initial) I.Q. 120 – 125. It appears that younger boys may benefit more than older ones in the same age-group. In so far as allocation is based on I.Qs. it has been shown that a programme of practice and coaching before selection would, for these boys, have affected the allocation of about 15 per cent of the grammar school places

The Rayleigh—Taylor problem with a vertical magnetic field, including the effects of Hall current and resistivity

The influence of resistivity and Hall current on the Rayleigh-Taylor problem involving two superposed fluids of finite density in the presence of gravitational and magnetic fields normal to the fluid interface is examined. Unlike the related problem in which the magnetic field is parallel to the interface, it appears that the dispersion relation does not exhibit singular behaviour in the zero resistivity limit. The ‘potentially stable' situation is considered throughout. The results are compared with earlier ideal and resistive theories, and an apparent anomaly regarding the existence of normal modes in such systems is resolve

An HI census of Loose Groups of Galaxies

We present results from our Parkes Multibeam HI survey of 3 loose groups of galaxies that are analogous to the Local Group. This is a survey of groups containing only spiral galaxies with mean separations of a few hundred kpc, and total areas of approximately 1 sq. Mpc; groups similar to our own Local Group. We present a census of the HI-rich objects in these groups down to an M(HI), 1-sigma sensitivity ~7x10^5 M(sun), as well as the detailed properties of these detections from follow-up Compact Array observations. We found 7 new HI-rich members in the 3 groups, all of which have stellar counterparts and are, therefore, typical dwarf galaxies. The ratio of low-mass to high-mass gas-rich galaxies in these groups is less than in the Local Group meaning that the ``missing satellite'' problem is not unique. No high-velocity cloud analogs were found in any of the groups. If HVCs in these groups are the same as in the Local Group, this implies that HVCs must be located within ~300-400 kpc of the Milky Way.Comment: 6 pages, to appear in the ASP proceedings of IAU Symposium 217, "Recycling intergalactic and interstellar matter", eds. Pierre-Alain Duc, Jonathan Braine, Elias Brink

Radio-optical scrutiny of compact AGN: Correlations between properties of pc-scale jets and optical nuclear emission

We study the correlations between the Very Long Baseline Array radio emission at 15 GHz, extended emission at 151 MHz, and optical nuclear emission at 5100 AA for a complete sample of 135 compact jets. We use the partial Kendall's tau correlation analysis to check the link between radio properties of parsec-scale jets and optical luminosities of host AGN. We find a significant positive correlation for 99 quasars between optical nuclear luminosities and total radio (VLBA) luminosities of unresolved cores at 15 GHz originated at milliarcseconds scales. For 18 BL Lacs, the optical continuum emission correlates with the radio emission of the jet at 15 GHz. We suggest that the radio and optical emission are beamed and originate in the innermost part of the sub--parsec-scale jet in quasars. Analysis of the relation between the apparent speed of the jet and the optical nuclear luminosity at 5100 AA supports the relativistic beaming model for the optical emission generated in the jet, and allows the peak values of the intrinsic optical luminosity of the jet and its Lorentz factor to be estimated for the populations of quasars, BL Lacs, and radio galaxies. The radio-loudness of quasars is found to increase at high redshifts, which can be a result of lower efficiency of the accretion in AGN having higher radio luminosities. A strong positive correlation is found between the intrinsic kinetic power of the jet and the apparent luminosities of the total and the unresolved core emission of the jet at 15 GHz. This correlation is interpreted in terms of intrinsically more luminous parsec-scale jet producing more luminous extended structure which is detectable at low radio frequencies, 151 MHz. A possibility that the low frequency radio emission is relativistically beamed in superluminal AGN and therefore correlates with radio luminosity of the jet at 15 GHz can not be ruled out (abridged).Comment: 16 pages, 10 figuers; minor comments are added; accepted to A&