2,844 research outputs found
A national scale inventory of resource provision for biodiversity within domestic gardens
The human population is increasingly disconnected from nature due to urbanisation. To counteract this phenomenon, the UK government has been actively promoting wildlife gardening. However, the extent to which such activities are conducted and the level of resource provision for biodiversity (e.g., food and nesting sites) within domestic gardens remains poorly documented. Here we generate estimates for a selection of key resources provided within gardens at a national scale, using 12 survey datasets gathered across the UK. We estimate that 22.7 million households (87% of homes) have access to a garden. Average garden SiZe is 190 m(2), extrapolating to a total area of 432,924 ha. Although substantial, this coverage is still an order of magnitude less than that of statutory protected areas. Approximately 12.6 million (48%) households provide supplementary food for birds, 7.4 million of which specifically use bird feeders. Similarly, there are a minimum of 4.7 million nest boxes within gardens. These figures equate to one bird feeder for every nine potentially feeder-using birds in the UK, and at least one nest box for every six breeding pairs of cavity nesting birds. Gardens also contain 2.5-3.5 million ponds and 28.7 million trees, which is just under a quarter of all trees occurring outside woodlands. Ongoing urbanisation, characterised by increased housing densities, is inevitable throughout the UK and elsewhere. The important contribution domestic gardens make to the green space infrastructure in residential areas must be acknowledged, as their reduction will impact biodiversity conservation, ecosystem services, and the well-being of the human population
Two new bright Ae stars
Two newly identified Ae stars, nu Cyg and kappa UMa, were discovered in the
course of the Magnetic Survey of Bright MS stars (Monin et al. 2002). We pre
sent their Halpha profiles along with measurements of their equivalent width
and parameters of emission features. Emission in the Halpha line of nu Cyg is
variable on a time scale of 3 years. kappa UMa exhibits weak emission which is
rather stable. The emission is thought to arise from a circumstellar disk, and
we have estimated the size of that disk.Both new emission stars are IRAS
sources. Their IR color excesses are consistent with those of classical Ae
stars. Thus, nu Cyg and kappa UMa appear not to belong to the class of Herbig
Ae/Be stars. We argue that the frequency of Ae stars may be underestimated due
to the difficulty of detection of weak emission in some A stars.Comment: 6 pages,3 figures, submitted to A&
Mass Dependence of M3Y-Type Interactions and the Effects of Tensor Correlations
The mass dependence of the M3Y-type effective interactions and the effects of
tensor correlations are examined. Two-body nuclear matrix elements are obtained
by the lowest order constrained variational (LOCV) technique with and without
tensor correlations. We have found that the tensor correlations are important
especially in the triplet-even (TE) and tensor-even (TNE) channels in order to
reproduce the G-matrix elements obtained previously. Then M3Y-type potentials
for inelastic scattering are obtained by fitting our two-body matrix elements
to those of a sum of Yukawa functions for the mass numbers A=24, A=40 and A=90.Comment: 13 pages, 6 table
What motivates the masses: understanding why people contribute to conservation citizen science projects
Participation in conservation citizen science projects is growing rapidly and approaches to project design are diversifying. There has been a recent shift towards projects characterised by contributors collecting data in isolation and submitting findings online, with little training or opportunities for direct social interaction with other citizen scientists. While research is emerging on developing citizen science projects by optimising technological modalities, little consideration has been given to understanding what motivates individuals to voluntarily contribute data. Here, we use the Volunteer Functions Inventory, combined with open-ended questions, to demonstrate that the two strongest motivations underpinning participation, for both individuals who contribute data systematically (regularly; n=177) and opportunistically (ad hoc basis; n=218), are ‘Values’ and ‘Understanding’. People take part in such projects because they have an intrinsic value for the environment and want to support research efforts (representing ‘Values’), as well as wanting to learn and gain knowledge (signifying ‘Understanding’). Unlike more traditional citizen science projects that involve specific training and considerable time investments, contributors to these newer types of project are not motivated by the potential to develop their career or opportunities for social interaction. The person36 level characteristics of contributors considered in this study did not reliably forecast levels of motivation, suggesting that predicting high levels of motivation is inherently more complex than is often speculated. We recommend avenues for future research that may further enhance our understanding of contributor motivations and the characteristics that may underpin levels of motivation
Two-to-one resonant multi-modal dynamics of horizontal/inclined cables. Part I : theoretical formulation and model validation
This paper is first of the two papers dealingwith analytical investigation of resonant multimodal dynamics due to 2:1 internal resonances in the finite-amplitude free vibrations of horizontal/inclined cables. Part I deals with theoretical formulation and validation of the general cable model. Approximate nonlinear partial differential equations of 3-D coupled motion of small sagged cables - which account for both spatio-temporal variation of nonlinear dynamic tension and system asymmetry due to inclined sagged configurations - are presented. A multidimensional Galerkin expansion of the solution ofnonplanar/planar motion is performed, yielding a complete set of system quadratic/cubic coefficients. With the aim of parametrically studying the behavior of horizontal/inclined cables in Part II [25], a second-order asymptotic analysis under planar 2:1 resonance is accomplished by the method of multiple scales. On accounting for higher-order effectsof quadratic/cubic nonlinearities, approximate closed form solutions of nonlinear amplitudes, frequencies and dynamic configurations of resonant nonlinear normal modes reveal the dependence of cable response on resonant/nonresonant modal contributions. Depending on simplifying kinematic modeling and assigned system parameters, approximate horizontal/inclined cable models are thoroughly validated by numerically evaluating statics and non-planar/planar linear/non-linear dynamics against those of the exact model. Moreover, the modal coupling role and contribution of system longitudinal dynamics are discussed for horizontal cables, showing some meaningful effects due to kinematic condensation
Albedo and Reflection Spectra of Extrasolar Giant Planets
We generate theoretical albedo and reflection spectra for a full range of
extrasolar giant planet (EGP) models, from Jovian to 51-Pegasi class objects.
Our albedo modeling utilizes the latest atomic and molecular cross sections, a
Mie theory treatment of extinction by condensates, a variety of particle size
distributions, and an extension of the Feautrier radiative transfer method
which allows for a general treatment of the scattering phase function. We find
that due to qualitative similarities in the compositions and spectra of objects
within each of five broad effective temperature ranges, it is natural to
establish five representative EGP albedo classes: a ``Jovian'' class (T K; Class I) with tropospheric ammonia clouds, a ``water
cloud'' class (T K; Class II) primarily affected by
condensed HO, a ``clear'' class (T K; Class III)
which lacks clouds, and two high-temperature classes: Class IV (900 K
T 1500 K) for which alkali metal absorption
predominates, and Class V (T 1500 K and/or low surface
gravity ( 10 cm s)) for which a high silicate layer
shields a significant fraction of the incident radiation from alkali metal and
molecular absorption. The resonance lines of sodium and potassium are expected
to be salient features in the reflection spectra of Class III, IV, and V
objects. We derive Bond albedos and effective temperatures for the full set of
known EGPs and explore the possible effects of non-equilibrium condensed
products of photolysis above or within principal cloud decks. As in Jupiter,
such species can lower the UV/blue albedo substantially, even if present in
relatively small mixing ratios.Comment: revised LaTeX manuscript accepted to Ap.J.; also available at
http://jupiter.as.arizona.edu/~burrows/paper
Feasibility of free space quantum key distribution with coherent polarization states
We demonstrate for the first time the feasibility of free space quantum key
distribution with continuous variables under real atmospheric conditions. More
specifically, we transmit coherent polarization states over a 100m free space
channel on the roof of our institute's building. In our scheme, signal and
local oscillator are combined in a single spatial mode which auto-compensates
atmospheric fluctuations and results in an excellent interference. Furthermore,
the local oscillator acts as spatial and spectral filter thus allowing
unrestrained daylight operation.Comment: 12 pages, 8 figures, extensions in sections 2, 3.1, 3.2 and 4. This
is an author-created, un-copyedited version of an article accepted for
publication in New Journal of Physics (Special Issue on Quantum Cryptography:
Theory and Practice). IOP Publishing Ltd is not responsible for any errors or
omissions in this version of the manuscript or any version derived from i
Crossing the `Yellow Void' -- Spatially Resolved Spectroscopy of the Post- Red Supergiant IRC+10420 and Its Circumstellar Ejecta
IRC +10420 is one of the extreme hypergiant stars that define the empirical
upper luminosity boundary in the HR diagram. During their post--RSG evolution,
these massive stars enter a temperature range (6000-9000 K) of increased
dynamical instability, high mass loss, and increasing opacity, a
semi--forbidden region, that de Jager and his collaborators have called the
`yellow void'. We report HST/STIS spatially resolved spectroscopy of IRC +10420
and its reflection nebula with some surprising results. Long slit spectroscopy
of the reflected spectrum allows us to effectively view the star from different
directions. Measurements of the double--peaked Halpha emission profile show a
uniform outflow of gas in a nearly spherical distribution, contrary to previous
models with an equatorial disk or bipolar outflow. Based on the temperature and
mass loss rate estimates that are usually quoted for this object, the wind is
optically thick to the continuum at some and possibly all wavelengths.
Consequently the observed variations in apparent spectral type and inferred
temperature are changes in the wind and do not necessarily mean that the
underlying stellar radius and interior structure are evolving on such a short
timescale. To explain the evidence for simultaneous outflow and infall of
material near the star, we propose a `rain' model in which blobs of gas
condense in regions of lowered opacity outside the dense wind. With the
apparent warming of its wind, the recent appearance of strong emission, and a
decline in the mass loss rate, IRC +10420 may be about to shed its opaque wind,
cross the `yellow void', and emerge as a hotter star.Comment: To appear in the Astronomical Journal, August 200
The influence of the cosmological expansion on local systems
Following renewed interest, the problem of whether the cosmological expansion
affects the dynamics of local systems is reconsidered. The cosmological
correction to the equations of motion in the locally inertial Fermi normal
frame (the relevant frame for astronomical observations) is computed. The
evolution equations for the cosmological perturbation of the two--body problem
are solved in this frame. The effect on the orbit is insignificant as are the
effects on the galactic and galactic--cluster scales.Comment: To appear in the Astrophysical Journal, Late
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