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New experimental and theoretical studies of low-density amorphous solid water (H2O(as)) and of polycrystalline ice lh are reported and integrated with other available data. A variety of evidence is put forward to support the conclusion that low-density H20(as) is derived from ice lh by slightly increasing the dispersion in the O—O separation and by introducing a distribution O—O—O angles (width c. 8°). Our theoretical analysis focusses attention on the consequences of strong intermolecular coupling of OH oscillators. The vibrational modes of both ice lh and H20(as) are found to be complex mixtures of molecular motions, so the identification of regions of the Raman or infrared spectra of these materials with particular isolated molecule modes is not useful. The theory developed gives a good, but not perfect, account of the OH stretching regions of the observed Raman and infrared spectra of ice lh and, to a lesser degree of low-density H20(as).
The mapping of stellar surfaces using the observed profiles of spectral lines is described. The problem is expressed in terms of an integral equation to be solved, using Tikhonov’s method. The local line profiles may be given either by an analytic approximation or by the solution of the equation of transfer with a model atmosphere. The model atmospheres commonly used may not correctly represent the stellar atmosphere which may lead to errors in the derived surface maps. Tests of mapping programs and applications to real stars show the capabilities and limitations of surface mapping. Mapping stellar magnetic fields places more severe demands on the data and computational programs than mapping the abundance distributions.
The atmospheric structures of magnetic CP2 (Ap) stars are notoriously difficult to model: line blanketing is severe, surface gravities are extremely uncertain, and the surface abundance inhomogeneities lead to different atmospheric properties as a function of position on the star. Seismology of the p-modes of rapidly oscillating Ap (roAp) stars (Kurtz 1990), which vary with periods of a few minutes and amplitudes below 0.01 mag and 1 km/s in light and velocity, has already helped constrain the luminosities – and hence, the logg values – of some cool CP2 stars (Kurtz 1992, these proceedings). We show here that the pulsations of an roAp star can also directly probe the temperature structure of a CP2 atmosphere.
We introduce a new polarimeter unit which, mounted at the Cassegrain focus of any telescope and fiber-connected to a fixed CCD spectrograph, is able to measure all Stokes parameters I, Q, U and V photon-noise limited across spectral lines of bright stellar targets and other point sources in a quasi-simultaneous manner. We briefly outline the technical design of the polarimeter unit and the linear algebraic Mueller calculus for obtaining polarization parameters of any point source. In addition, practical limitations of the optical elements are discussed. We present first results obtained with our spectropolarimeter for three prototype hot-star.
Rapidly oscillating Ap (roAp) stars are cool magnetic CP2 stars which vary with periods of a few minutes and amplitudes less than 0.01 mag and 1 km/s in light and velocity. Analysis of their p-mode eigenfrequency patterns and splittings gives information about evolutionary state, rotation rate, magnetic field geometry and internal field strength (see Kurtz 1990; Matthews 1991).
We present here an example of how roAp pulsations can be used to obtain an estimate of the temperature structure of an Ap atmosphere.
The pulsation amplitudes of roAp stars decline more rapidly with increasing wavelength than other known pulsators. Matthews et al. (1990) explained this by the wavelength dependence of limb darkening and its weighting effect on the integrated amplitude of an (l, m) = (1,0) mode.
The innermost parsec around Sgr A* has been found to play host to two disks or streamers of O and W-R stars. They are misaligned by an angle approaching 90°. That the stars are approximately coeval indicates that they formed in the same event rather than independently. We have performed smoothed particle hydrodynamic simulations of the infall of a single prolate cloud towards a massive black hole. As the cloud is disrupted, the large spread in angular momentum can, if conditions allow, lead to the creation of misaligned gas disks. In turn, stars may form within those disks. We are now investigating the origins of these clouds in the Galactic center (GC) region.
The styli, often called the aristae, of the antennae of adult Sepedon fuscipennis Loew (Diptera: Sciomyzidae) are shown to possess mechanosensilla, the number and arrangement of which differ between the sexes. It is suggested that the mechanosensilla provide sensory input to the female regarding the touching, or appositioning, of her styli by the male with his forelegs during copulation. Among the Sciomyzidae, S.fuscipennis males are unique in appositioning the antennae of the female during mating. Large clusters of pollen found on the styli of both sexes suggest that mechanosensilla and chemosensilla also provide sensory information about potential sources of food such as nectar (i.e., carbohydrates).
The late discovery of a Vessel under the ancient bed of the river Rother having given rise to various conjectures and contradictory statements, respecting her age and former service, and the subject being of some interest in naval architecture, I was directed by Sir Byam Martin, at the request of Lord Melville, to repair to the place where she was found, and to obtain a true account of her build and situation; in order, if possible, to ascertain the country she belonged to, and the period of her submersion. My Report has been subsequently transmitted to the Admiralty; and, at the suggestion of Mr. Barrow, I have taken the liberty of addressing to you a Letter, containing the substance of that Report; and should the subject be compatible with the regulations as to Papers usually read at the Society of Antiquaries, it will afford me much satisfaction if you will do me the favour to introduce it at the ensuing meeting.
It is well established that the presence of prominent anxiety within depressive episodes portends poorer outcomes. Important questions remain as to which anxiety features are important to outcome and how sustained their prognostic effects are over time.
To examine the relative prognostic importance of specific anxiety features and to determine whether their effects persist over decades and apply to both unipolar and bipolar conditions.
Participants with unipolar (n = 476) or bipolar (n = 335) depressive disorders were intensively followed for a mean of 16.7 years (s.d. = 8.5).
The number and severity of anxiety symptoms, but not the presence of pre-existing anxiety disorders, showed a robust and continuous relationship to the subsequent time spent in depressive episodes in both unipolar and bipolar depressive disorder. The strength of this relationship changed little over five successive 5-year periods.
The severity of current anxiety symptoms within depressive episodes correlates strongly with the persistence of subsequent depressive symptoms and this relationship is stable over decades.
Objectives: There is evidence that breastmilk feeding reduces mortality and short and long-term morbidity among infants born too soon or too small. The aim of this study was to evaluate the cost-effectiveness of enhanced staff contact for mothers with infants in a neonatal unit with a birth weight of 500–2,500 g from the perspective of the UK National Health Service.
Methods: A decision-tree model linked clinical outcomes with long-term health outcomes. The study population was divided into three weight bands: 500–999 g, 1000–1,749 g, and 1,750–2,500 g. Clinical and resource use data were obtained from literature reviews. The measure of benefit was quality-adjusted life-years. Uncertainty was evaluated using cost-effectiveness acceptability curves and sensitivity analyses.
Results: The intervention was less costly and more effective than the comparator in the base–case analysis for each birth weight group. The results were quite robust to the sensitivity analyses performed.
Conclusions: This is the first economic evaluation in this complex field and offers a model to be developed in future research. The results provide preliminary indications that enhanced staff contact may be cost-effective. However, the limited evidence available, and the limited UK data in particular, suggest that further research is required to provide results with confidence.
Permanent pastures produce far below their potential, as they are usually managed in the northcentral and northeastern United States. Dairy farmers in these regions generally feed their cattle year-round from stored forage and purchased concentrates, and use permanent pastures as mere holding or exercise areas, grazing them continuously. This practice involves high operating costs that, combined with lower milk prices, have resulted in greatly reduced profit margins. Farming practices that return more net income are needed. The Voisin system of rotational grazing management, which applies intensive management to forage crops on pastureland, is widely used on dairy and sheep farms in New Zealand. Farmers using the Voisin system there have low operating costs and obtain high yields of excellent quality forage over long grazing periods; increased net income results Between 1 May and 1 October 1984, 497 forage samples were taken and analyzed from permanent pastures grazed according to the Voisin management system on six Vermont dairy farms. This was done to provide farmers with current estimates of forage feeding value so that they could balance their cows' rations accordingly throughout the season, and determine if they could improve the profitability of their farms by using Voisin grazing management. Average grazingseason analyses (dry weight) were: 22.5% dry matter, 22.4% crude protein, 20.8% available protein, 28.4% acid detergent fiber, 1.18% calcium, .48% phosphorus, 1.60% potassium, .22% magnesium, and 1.58 Mcal/kg net energy lactation. Average dry forage yield was 8.9 metric tons/ha. Dry matter intake was adequate for milk production up to 36 kg/cow/day. Forage protein and energy contents were sufficient for at least 25 and 18 kg milk/day, respectively. On three farms where economic factors were calculated, net profits per cow averaged $67 more during the 5-month period from using Voisin grazing management, compared to continuous grazing of the same pastureland in the year before Voisin management was used. This profit resulted mainly from feed savings and a more favorable milk:concentrate ratio of 4.1:1 obtained with Voisin management, compared to 2.7:1 with continuous grazing and more feeding of stored or machine-harvested forage. Voisin-managed pastures can produce high yields of excellent-quality forage that can be incorporated into dairy feeding programs, thereby reducing feed costs and increasing profitability of the farming operations.