3,205 research outputs found
Blue, white, and red ocean planets - Simulations of orbital variations in flux and polarization colors
An exoplanet's habitability will depend strongly on the presence of liquid
water. Flux and/or polarization measurements of starlight that is reflected by
exoplanets could help to identify exo-oceans. We investigate which broadband
spectral features in flux and polarization phase functions of reflected
starlight uniquely identify exo-oceans. We compute total fluxes F and polarized
fluxes Q of starlight reflected by cloud-free and (partly) cloudy exoplanets,
for wavelengths from 350 to 865 nm. The ocean surface has waves composed of
Fresnel reflecting wave facets and whitecaps, and scattering within the water
body is included. Total flux F, polarized flux Q, and degree of polarization P
of ocean planets change color from blue, through white, to red at phase angles
alpha ranging from 134-108 deg for F, and from 123-157 deg for Q, with cloud
coverage fraction fc increasing from 0.0 to 1.0 for F, and to 0.98 for Q. The
color change in P only occurs for fc ranging from 0.03-0.98, with the color
crossing angle alpha ranging from 88-161 deg. The total flux F of a cloudy,
zero surface albedo planet can also change color, and for fc=0.0, an ocean
planet's F will not change color for surface pressures ps > 8 bars. Polarized
flux Q of a zero surface albedo planet does not change color for any fc. The
color change of P of starlight reflected by an exoplanet, from blue, through
white, to red with increasing alpha above 88 deg, appears to identify a
(partly) cloudy exo-ocean. The color change of polarized flux Q with increasing
alpha above 123 deg appears to uniquely identify an exo-ocean, independent of
surface pressure or cloud fraction. At the color changing phase angle, the
angular distance between a star and its planet is much larger than at the phase
angle where the glint appears in reflected light. The color change in
polarization thus offers better prospects for detecting exo-oceans.Comment: Accepted for publication in Astron. Astrophys; multicolumn versio
A novel strategy to reduce dizziness:Applying a prognosis-oriented approach in older patients in general practice
Horst, H.E. van der [Promotor]Maarsingh, O.R. [Copromotor]Wouden, J.C. van der [Copromotor
Metabolism: flow and contractility of the Langendorff heart
This thesis reviews current literature and describes
experimental studies on the regulation and modification of
coronary flow and contractility in isolated rat hearts. In
chapter I and introduction is given to the problems of fatty
acid toxicity and myocardial function. Coronary flow rate and
pump function of the myocardium are mainly determined by the
contractile status of vascular smooth muscle cells and cardiac
striated muscle cells, respectively. Therefore in chapters II
and III morphological and (ultra)structural aspects of both
types of cells have been described.
In chapters IV and V functional and metabolic aspects of coronary
circulation and contractility are illustrated. In both vascular
smooth and cardiac striated muscle cells:
(i) the intracellular calcium concentration is the
main determinant of the contractile status of
actomyosin,
(ii) contraction takes place after the action potentialinduced
calcium-influx through the plasmamembrane
and calcium release from intracellular stores
(sarcoplasmic reticulum, mitochondria),
(iii) relaxation is achieved after reduction of the cytoplasmic
calcium level by calcium-pump systems in
the plasmamembrane, sarcoplasmic reticulum and
mitochondria,
(iv) calcium-ions trigger the coupling between the
contraction-relaxation cycle with energy metabolism
since glycogenolysis and lipolysis are both
stimulated by calcium
Peaks of Joy, Valleys of Despair: The History of the Syracuse University Library from 1871 to 1907
Drawing on a variety of sources, Starn presents engaging samples of life in the early days of the Syracuse University Library
Preface: A Special Stephen Crane Issue
One of the great pleasures of coming to a new library, as I did to Syracuse last March, is the joy of discovering particularly strong but unexpected collections. The Leopold von Ranke holdings, the Margaret Bourke,White collection, and the Belfer Audio Archives are just a few of the great strengths of the Syracuse University Libraries and its special collections
Transboundary Air Pollution in Europe: An Interactive Multicriteria Tradeoff Analysis
In this paper. the acid rain problem in Europe is discussed, stressing the transboundary tradeoffs between abatement costs of sulphur emission reduction and corresponding deposition levels in the different countries. An interactive decision support methodology is proposed which utilizes a powerful nonlinear multicriteria software package to evaluate various scenarios and tradeoffs. The concepts are illustrated using previously published data. The results from the tradeoff analysis show that reasonable deposition levels can be reached with limited transfers of funds between countries. The extent of these transfers can be controlled by selecting appropriate target levels for the criteria across countries
Scattering matrices and expansion coefficients of Martian analogue palagonite particles
We present measurements of ratios of elements of the scattering matrix of
Martian analogue palagonite particles for scattering angles ranging from 3 to
174 degrees and a wavelength of 632.8 nm. To facilitate the use of these
measurements in radiative transfer calculations we have devised a method that
enables us to obtain, from these measurements, a normalized synthetic
scattering matrix covering the complete scattering angle range from 0 to 180
degrees. Our method is based on employing the coefficients of the expansions of
scattering matrix elements into generalized spherical functions. The synthetic
scattering matrix elements and/or the expansion coefficients obtained in this
way, can be used to include multiple scattering by these irregularly shaped
particles in (polarized) radiative transfer calculations, such as calculations
of sunlight that is scattered in the dusty Martian atmosphere.Comment: 34 pages 7 figures 1 tabl
- …