Role of nitric oxide in maintenance of basal oral tissue blood flow in anesthetized cats

Experiments were undertaken to determine if nitric oxide (NO) plays a role in regulation of basal blood flow in the oral cavity of pentobarbital anesthetized cats and, if so, to quantify this effect using dose-response relationships. Blood flow was continuously measured from the surface of the tongue and mandibular gingiva (laser-Doppler flowmetry) and from the lingual artery (ultrasonic flowmetry). Cardiovascular parameters also were recorded. Administration of the nonselective inhibitor of nitric oxide synthase (NOS), L-NAME (0.08-20 mg/kg i.v.), produced a dose-related increase of blood pressure associated with decreases of blood flow at all three measurement sites. Maximal blood flow depression of 50-60% was seen 30-60 min after administration of 1.25 mg/kg of L-NAME. D-NAME (1.25 mg/kg i.v.) was inactive at all sites. Subsequent administration of L-arginine partially reversed effects of L-NAME in the lingual artery and tongue, but not in the gingival circulation. The neuronally selective NOS inhibitor, 7-nitroindazole (7-NI, 30 mg/kg i.p.), was devoid of effect on any of the measured parameters. These results suggest that endothelial (but not neuronally derived) NO plays an important role in control of basal blood flow in oral tissues of the cat.

Susceptibility of streptozotocin-induced diabetic rat retinal function and ocular blood flow to acute intraocular pressure challenge.

PURPOSE: To consider whether STZ-induced hyperglycemia renders rat retinal function and ocular blood flow more susceptible to acute intraocular pressure (IOP) challenge.

METHODS: Retinal function (electroretinogram, ERG) was measured during acute IOP challenge (10-100 mmHg, 5 mmHg increments, 3 min/step, vitreal cannulation) in adult Long-Evans rats (6-week old, citrate: n=6, STZ: n=10) 4 weeks after citrate buffer or streptozotocin (STZ, 65 mg/kg, blood glucose > 15 mmol/l) injection. At each IOP, dim and bright flash (-4.56, -1.72 log cd.s.m^-2) ERG responses were recorded to measure inner retinal and ON-bipolar cell function, respectively. Ocular blood flow (laser Doppler flowmetry, citrate; n=6, STZ; n=10) was also measured during acute IOP challenge. Retinae were isolated for qPCR analysis of nitric oxide synthase mRNA expression endothelial, eNos; inducible, iNos; neuronal, nNos).

RESULTS: STZ-induced diabetes increased the susceptibility of inner retinal (IOP at 50% response, 60.1, CI: 57.0-62.0 mmHg vs. citrate: 67.5, CI: 62.1-72.4 mmHg) and ON-bipolar cell function (STZ: 60.3, CI: 58.0-62.8 mmHg vs. citrate: 65.1, CI: 58.0-62.78 mmHg) and ocular blood flow (43.9, CI: 40.8-46.8 vs. citrate: 53.4, CI: 50.7-56.1 mmHg) to IOP challenge. Citrate eyes showed elevated eNos mRNA (+49.7%) after IOP stress, an effect not found in STZ-diabetic eyes (-5.7%, P<0.03). No difference was observed for iNos or nNos (P>0.05) following IOP elevation.

CONCLUSIONS: STZ-induced diabetes increased functional susceptibility during acute IOP challenge. This functional vulnerability is associated with a reduced capacity for diabetic eyes to upregulate eNOS expression and to autoregulate blood flow in response to stress.

Charge-state distribution and Doppler effect in an expanding photoionized plasma.

The charge state distributions of Fe, Na, and F are determined in a photoionized laboratory plasma using high resolution x-ray spectroscopy. Independent measurements of the density and radiation flux indicate unprecedented values for the ionization parameter ���¾=20 25 erg cm s-1 under near steady-state conditions. Line opacities are well fitted by a curve-of-growth analysis which includes the effects of velocity gradients in a one-dimensional expanding plasma. First comparisons of the measured charge state distributions with x-ray photoionization models show reasonable agreement.

Doppler cooling of gallium atoms: 1. Fine structure effects and transient coherences

A realistic model of the dipole radiation forces in transverse Doppler cooling (with a s+-s- laser configuration) of an atomic beam of group 13 elements is studied within the quantum-kinetic equation framework. The full energy level sub-structure for such an atom with I = 0 (such as 66Ga) is analysed. Two cooling strategies are investigated; the first involving the 2P3/2 ? 2D5/2 transition and the second a dual laser cooling experiment involving transitions 2P1/2 and 2P3/2 ? 2S1/2. The latter scheme creates a velocity-independent dark-state resonance that inhibits a steady-state dipole cooling force. However, time-dependent calculations show that transient cooling forces are present that could be exploited for laser cooling purposes in pulsed laser fields.

Stokes imaging, Doppler mapping and Roche tomography of the AM Herculis system V834 Cen

We report on new simultaneous phase-resolved spectroscopic and polarimetric observations of the polar (AM Herculis star) V834 Cen during a high state of accretion. Strong emission lines and high levels of variable circular and linear polarization are observed over the orbital period. The polarization data are modelled using the Stokes imaging technique of Potter et al. The spectroscopic emission lines are investigated using the Doppler tomography technique of Marsh and Horne and the Roche tomography technique of Dhillon and Watson. Up to now, all three techniques have been used separately to investigate the geometry and accretion dynamics in cataclysmic variables. For the first time, we apply all three techniques to simultaneous data for a single system. This allows us to compare and test each of the techniques against each other and hence to derive a better understanding of the geometry, dynamics and system parameters of V834 Cen.

Doppler cooling of gallium atoms: 2. Simulation in complex multilevel systems

This paper derives a general procedure for the numerical solution of the Lindblad equations that govern the coherences arising from multicoloured light interacting with a multilevel system. A systematic approach to finding the conservative and dissipative terms is derived and applied to the laser cooling of p-block elements. An improved numerical method is developed to solve the time-dependent master equation and results are presented for transient cooling processes. The method is significantly more robust, efficient and accurate than the standard method and can be applied to a broad range of atomic and molecular systems. Radiation pressure forces and the formation of dynamic dark states are studied in the gallium isotope 66Ga.

The Doppler shadow of WASP-3b. A tomographic analysis of Rossiter-McLaughlin observations

Context. Hot-Jupiter planets must form at large separations from their host stars where the temperatures are cool enough for their cores to condense. They then migrate inwards to their current observed orbital separations. Different theories of how this migration occurs lead to varying distributions of orbital eccentricity and the alignment between the rotation axis of the star and the orbital axis of the planet. Aims: The spin-orbit alignment of a transiting system is revealed via the Rossiter-McLaughlin effect, which is the anomaly present in the radial velocity measurements of the rotating star during transit due to the planet blocking some of the starlight. In this paper we aim to measure the spin-orbit alignment of the WASP-3 system via a new way of analysing the Rossiter-McLaughlin observations. Methods: We apply a new tomographic method for analysing the time variable asymmetry of stellar line profiles caused by the Rossiter-McLaughlin effect. This new method eliminates the systematic error inherent in previous methods used to analyse the effect. Results: We find a value for the projected stellar spin rate of v sin i = 13.9 ± 0.03 km s-1 which is in agreement with previous measurements but has a much higher precision. The system is found to be well aligned, with ? = 5-5+6° which favours an evolutionary history for WASP-3b involving migration through tidal interactions with a protoplanetary disc. From comparison with isochrones we put an upper limit on the age of the star of 2 Gyr.

Colour Doppler ultrasound of the ocular circulation in patients with systemic lupus erythematosus identifies altered microcirculatory haemodynamics

We assessed whether quantitative analysis of Doppler flow velocity waveforms is able to identify subclinical microvascular abnormalities in SLE and whether eigenvector analysis can detect changes not detectable using the resistive index (RI). Fifty-four SLE patients with no conventional cardiovascular risk factors, major organ involvement or retinopathy were compared to 32 controls. Flow velocity waveforms were obtained from the ophthalmic artery (OA), central retinal artery (CRA) and common carotid artery (CA). The waveforms were analysed using eigenvector decomposition and compared between groups at each arterial site. The RI was also determined. The RI was comparable between groups. In the OA and CRA, there were significant differences in the lower frequency sinusoidal components (P <0.05 for each component). No differences were apparent in the CA between groups. Eigenvector analysis of Doppler flow waveforms, recorded in proximity of the terminal vascular bed, identified altered ocular microvascular haemodynamics in SLE. Altered waveform structure could not be identified by changes in RI, the traditional measure of downstream vascular resistance. This analytical approach to waveform analysis is more sensitive in detecting preclinical microvascular abnormalities in SLE. It may hold potential as a useful tool for assessing disease activity, response to treatment, and predicting future vascular complications.

Eclipsing Binary Science via the Merging of Transit and Doppler Exoplanet Survey Data—A Case Study with the MARVELS Pilot Project and SuperWASP

Exoplanet transit and Doppler surveys discover many binary stars during their operation that can be used to conduct a variety of ancillary science. Specifically, eclipsing binary stars can be used to study the stellar mass-radius relationship and to test predictions of theoretical stellar evolution models. By cross-referencing 24 binary stars found in the MARVELS Pilot Project with SuperWASP photometry, we find two new eclipsing binaries, TYC 0272-00458-1 and TYC 1422-01328-1, which we use as case studies to develop a general approach to eclipsing binaries in survey data. TYC 0272-00458-1 is a single-lined spectroscopic binary for which we calculate a mass of the secondary and radii for both components using reasonable constraints on the primary mass through several different techniques. For a primary mass of M 1 = 0.92 ± 0.1 M sun, we find M 2 = 0.610 ± 0.036 M sun, R 1 = 0.932 ± 0.076 R sun, and R 2 = 0.559 ± 0.102 R sun, and find that both stars have masses and radii consistent with model predictions. TYC 1422-01328-1 is a triple-component system for which we can directly measure the masses and radii of the eclipsing pair. We find that the eclipsing pair consists of an evolved primary star (M 1 = 1.163 ± 0.034 M sun, R 1 = 2.063 ± 0.058 R sun) and a G-type dwarf secondary (M 2 = 0.905 ± 0.067 M sun, R 2 = 0.887 ± 0.037 R sun). We provide the framework necessary to apply this analysis to much larger data sets.

Measurements of the hole boring velocity from Doppler shifted harmonic emission from solid targets

The fast ignitor scheme for inertial confinement fusion requires forward driving of the critical density surface by light pressure (hole boring) to allow energy deposition close to the dense fuel. The recession velocity of the critical density surface has been observed to be nu/c = 0.015 at an irradiance of 1.0 x 10(19) W cm(-2) at a wavelength of 1.05 micron, in quantitative agreement with modeling. (C) 1996 American Institute of Physics.

Ultracold fluorine production via Doppler cooled BeF

Large parts of the periodic table cannot be cooled by current laser-based methods. We investigate whether zero energy fragmentation of laser cooled fluorides is a potential source of ultracold fluorine atoms. We report new ab initio calculations on the lowest electronic states of the BeF diatomic molecule including spin-orbit coupling, the calculated minima for the valence electronic states being within 1 pm of the spectroscopic values. A four colour cooling scheme based on the A2? ? X2S+ transition is shown to be feasible for this molecule. Multi-Reference Configuration Interaction (MRCI) potentials of the lowest energy Rydberg states are reported for the first time and found to be in good agreement with experimental data. A series of multi-pulse excitation schemes from a single rovibrational level of the cooled molecule are proposed to produce cold fluorine atoms.