Far Infrared Spectroscopy

Contains a report on a research project.National Science Foundation (Grant G-19637

Contributions to the Study of the Morphology of Fish

From the observations chronicled above it will be seen that Callichthys has several primitive features, while being in many ways a typical Teleost. The main points of interest in its development are: 1. The process of segmentation is similar to that of the egg of Salmo. 2. Development is very rapid and the embryo has many adult features by the time of hatching. 3. The chondrocranium is of the primitive platybasic type, and the trabeculae and parachordals are continuous. 4. The cartilaginous pectoral girdle closely resembles the visceral arches. 5. The anterior part of the vertebral column, with the air-sac capsule connected with it, is similar to that of other Siluridae, except that the first normal, probably the fifth, vertebra carries a large rib, comparable with the cranial rib of the Dipnoi. 6. The bony plates of the body, and probably some of the superficial bones of the skull, are of dermal origin. The bony plates have a row of denticles along their posterior border, similar to the denticles on the lepidotrichia of the paired and unpaired fins. 7. In the otocyst the two endolymphatic ducts meet in the middle line ventral to the brain, and send back a little diverticulum, the sinus endolymphaticus, which is embraced at the sides by the discs of the air-sacs. 8. The air-bladder is represented in the adult by a pair of air-sacs lying at either side in a bony capsule just behind the ear, with which they are connected by means of the Weberian apparatus. 9. The arrangement of the lateral line sense organs on the head is similar to that of the sense organs on the head of Osteolepis, one of the fossil Ganoids. 10. The gills are normal, but the fish also breathes by its membranous and vascular intestine. Probably the caudal and dorsal fins have a respiratory function as they are very vascular, especially during development. 11. The heart has a muscular conus. The last two afferents of each side come from the dorsal side of the ventral aorta as a single vessel, as they do in the Dipnoi. 12. The caudal vein continues forward as the inter-renal vein, which is again continuous with the right posterior cardinal. The left posterior cardinal is very short and in the adult has lost its connection with the inter-renal. There is a single inferior jugular vein, comparable with that of Polypterus, which opens into the right side of the atrium. 13. The development of the pectoral fins is somewhat similar to that of the pectoral fins of Polypterus, the fin having at first a solid axis with a fold of membrane around it. 14. There appears to be a persistent pronephros with a single very much enlarged glomerulus, right at the front of the opisthonephros in the middle line

Syntheses and Structural Elucidation of Natural Coumarins

A short review of natural coumarins is given which incorporates some of the structural features and biosynthetic aspects of those coumarins unsubstituted at positions 3 and 4. All of the 5,7-dioxygenated simple coumarins, known to occur naturally, have been tabulated. Part I The 'Claisen Rearrangement' has been investigated as a method of synthesising ortho-(1,1-dimethylallyl)hydroxy-coumarins. Thus, pyrolysis of 7-0-(3,3-dimethylallyl)scopoletin(61) yielded obliquetin(62) and the corresponding cyclic ether, nieshoutin(63). A third product of this pyrolysis was 3-(1,1-dimethylallyl)scopoletin(76), the result of a triple 'Claisen Rearrangement'. In a similar manner, 7-0-(3,3-dimethylallyl)-5-methoxy-coumarin(120) was converted to a phenol which was trapped as the butyrate. Hydrolysis and methylation yielded the coumarin pinnarin(122). A general study of the 'Claisen Rearrangement' products of the 7-0-(3,3-dimethylallyl) ethers of the following coumarins was made, namely aesculetin(19), 4-methylscopoletin(101), umbelliferone(4) and 4-methylumbelliferone(115). Part II A new method of introducing a 3,3-dimethylallyl unit ortho to a phenol has been developed. The 1,1-dimethylpropargyl ethers of umbelliferone(4) and 7-hydroxy-5-methoxycoumarin were prepared and then selectively reduced to the corresponding 1,1-dimethylallyloxycoumarins. Pyrolyses of the latter ethers enabled the natural coumarins, osthenol(21), 7-demethylsuberosin (22), osthol(146), suberosin(147) and coumurrayin(131) to be prepared. Part III The structure of nieshoutol(160), the only trioxygenated coumarin isolated from the heartwood of Ptaeroxylon obliquum, was deduced from chemical and spectroscopic evidence. The ortho relationship of the phenolic hydroxyl to the oxygen of the 2,3,3-trimethyldihydrofuran ring was determined by n. m. r. shielding effects. Demethylation, ester interchange and cyclic ketal formation showed that the methoxyl of nieshoutol is ortho to the phenolic hydroxyl. Structure 160 was confirmed when a nuclear Overhauser effect was observed between the methoxyl and the C-4 proton

Constraining Radiatively Inefficient Accretion Flows with Polarization

The low-luminosity black hole Sgr A* provides a testbed for models of Radiatively Inefficient Accretion Flows (RIAFs). Recent sub-millimeter linear polarization measurements of Sgr A* have provided evidence that the electrons in the accretion flow are relativistic over a large range of radii. Here, we show that these high temperatures result in elliptical plasma normal modes. Thus, polarized millimeter and sub-millimeter radiation emitted within RIAFs will undergo generalized Faraday rotation, a cyclic conversion between linear and circular polarization. This effect will not depolarize the radiation even if the rotation measure is extremely high. Rather, the beam will take on the linear and circular polarization properties of the plasma normal modes. As a result, polarization measurements of Sgr A* in this frequency regime will constrain the temperature, density and magnetic profiles of RIAF models.Comment: 4 pages, 3 figures, accepted by ApJ Letter

The luminous X-ray hotspot in 4C 74.26: synchrotron or inverse-Compton emission?

We report the discovery of an X-ray counterpart to the southern radio hotspot of the largest-known radio quasar 4C 74.26 (whose redshift is z=0.104). Both XMM-Newton and Chandra images reveal the same significant (10arcsec, i.e. 19kpc) offset between the X-ray hotspot and the radio hotspot imaged with MERLIN. The peak of the X-ray emission may be due to synchrotron or inverse-Compton emission. If synchrotron emission, the hotspot represents the site of particle acceleration and the offset arises from either the jet exhibiting Scheuer's `dentist's drill' effect or a fast spine having less momentum than the sheath surrounding it, which creates the radio hotspot. If the emission arises from the inverse-Compton process, it must be inverse-Compton scattering of the CMB in a decelerating relativistic flow, implying that the jet is relativistic (Gamma >= 2) out to a distance of at least 800kpc. Our analysis, including optical data from the Liverpool Telescope, rules out a background AGN for the X-ray emission and confirms its nature as a hotspot, making it the most X-ray luminous hotspot yet detected.Comment: 9 pages, 9 figures, definitive version published by MNRA

Galactic center at very high-energies

Employing data collected during the first 25 months' observations by the Fermi-LAT, we describe and subsequently seek to model the very high energy (>300 MeV) emission from the central few parsecs of our Galaxy. We analyze the morphological, spectral and temporal characteristics of the central source, 1FGL J1745.6-2900. Remarkably, the data show a clear, statistically significant signal at energies above 10 GeV, where the Fermi-LAT has an excellent angular resolution comparable to the angular resolution of HESS at TeV energies, which makes meaningful the joint analysis of the Fermi and HESS data. Our analysis does not show statistically significant variability of 1FGL J1745.6-2900. Using the combination of Fermi data on 1FGL J1745.6-2900 and HESS data on the coincident, TeV source HESS J1745-290, we show that the spectrum of the central gamma-ray source is inflected with a relatively steep spectral region matching between the flatter spectrum found at both low and high energies. We seek to model the gamma-ray production in the inner 10 pc of the Galaxy and examine, in particular, cosmic ray (CR) proton propagation scenarios that reproduce the observed spectrum of the central source. We show that a model that instantiates a transition from diffusive propagation of the CR protons at low energy to almost rectilinear propagation at high energies (given a reasonable energy-dependence of the assumed diffusion coefficient) can well explain the spectral phenomenology. In general, however, we find considerable degeneracy between different parameter choices which will only be broken with the addition of morphological information that gamma-ray telescopes cannot deliver given current angular resolution limits.We argue that a future analysis done in combination with higher-resolution radio continuum data holds out the promise of breaking this degeneracy.Comment: submitted to Ap

Hydrothermal alteration at the Roosevelt hot springs thermal area, Utah: Petrographic characterization of the alteration to 2 kilometers depth

Hydrothermal alteration in drill cuttings from Thermal Power drillhole 14-2, Roosevelt Hot Springs Thermal area, has been studied petrographically. The hole is sited in alluvium approximately 1.6 km southeast of the old Resort and was rotary drilled to a depth of 1866.0 m. The exact hole location is 2310 FNL, 350 FWL, Sec. 2, Twp 27S, Rge 9W, elevation 1908.5 m. Core was extracted from 792.5 to 795.5 m. Thin sections were made from samples 15.2 m intervals of drill cuttings collected at 1.5 or 3.0 m intervals during drilling. Thin sections were made of 1.5 or 3.0 m intervals from 274.3 to 304.8 m, 487.9 to 581.2 m, and 868.7 t o 899.2 m. These intervals were chosen for close spaced sampling on the basis of increases in temperature, porosity, conductivity and acoustic velocity shown in geophysical logs. A total of 153 thin sections of cuttings were made, and an additional 9 sections were made from the core. Depths of thin section samples are listed in the appendix. A visual estimate of the percentage of each rock type was made for each thin section