8,901 research outputs found
Optimizing the scale of markets for water quality trading
Applying market approaches to environmental regulations requires establishing a spatial scale for trading. Spatially large markets usually increase opportunities for abatement cost savings but increase the potential for pollution damages (hot spots), vice versa for spatially small markets. We develop a coupled hydrologic-economic modeling approach for application to point source emissions trading by a large number of sources and apply this approach to the wastewater treatment plants (WWTPs) within the watershed of the second largest estuary in the U.S. We consider two different administrative structures that govern the trade of emission permits: one-for-one trading (the number of permits required for each unit of emission is the same for every WWTP) and trading ratios (the number of permits required for each unit of emissions varies across WWTP). Results show that water quality regulators should allow trading to occur at the river basin scale as an appropriate first-step policy, as is being done in a limited number of cases via compliance associations. Larger spatial scales may be needed under conditions of increased abatement costs. The optimal scale of the market is generally the same regardless of whether one-for-one trading or trading ratios are employed
The Super Lithium-Rich Red Giant Rapid Rotator G0928+73.2600: A Case for Planet Accretion?
We present the discovery of a super lithium-rich K giant star, G0928+73.2600.
This red giant (T_eff = 4885 K and log g = 2.65) is a fast rotator with a
projected rotational velocity of 8.4 km/s and an unusually high lithium
abundance of A(Li) = 3.30 dex. Although the lack of a measured parallax
precludes knowing the exact evolutionary phase, an isochrone-derived estimate
of its luminosity places the star on the Hertzsprung-Russell diagram in a
location that is not consistent with either the red bump on the first ascent of
the red giant branch or with the second ascent on the asymptotic giant branch,
the two evolutionary stages where lithium-rich giant stars tend to cluster.
Thus, even among the already unusual group of lithium-rich giant stars,
G0928+73.2600 is peculiar. Using 12C/13C as a tracer for mixing---more mixing
leads to lower 12C/13C---we find 12C/13C = 28, which is near the expected value
for standard first dredge-up mixing. We can therefore conclude that "extra"
deep mixing has not occurred. Regardless of the ambiguity of the evolutionary
stage, the extremely large lithium abundance and the rotational velocity of
this star are unusual, and we speculate that G0928+73.2600 has been enriched in
both lithium and angular momentum from a sub-stellar companion.Comment: 5 pages, 4 figures, Accepted by ApJ Letter
An Irradiation Effect in Nova DN Gem 1912 and the Significance of the Period Gap for Classical Novae
Continuous CCD photometry of the classical nova DN Gem during 52 nights in
the years 1992-98 reveals a modulation with a period 0.127844 d. The
semi-amplitude is about 0.03 mag. The stability of the variation suggests that
it is the orbital period of the binary system. This interpretation makes DN Gem
the fourth nova inside the cataclysmic variable (CV) period gap, as defined by
Diaz and Bruch (1997), and it bolsters the idea that there is no period gap for
classical novae. However, the number of known nova periods is still too small
to establish this idea statistically. We eliminate several possible mechanisms
for the variation, and propose that the modulation is driven by an irradiation
effect. We find that model light curves of an irradiated secondary star, fit
the data well. The inclination angle of the system is restricted by this model
to 10 deg < i < 65 deg. We also refine a previous estimate of the distance to
the binary system, and find d=1.6+/-0.6 kpc.Comment: 7 pages, Latex file, 2 .ps files and 3 .eps files. accepted for
publication in MNRAS. also available at:
ftp://ftp.astro.keele.ac.uk/pub/preprints/preprints.htm
An extensive photometric study of the recently discovered intermediate polar V515 And (XSS J00564+4548)
We report results of photometry of the intermediate polar V515 And. The
observations were obtained over 33 nights in 2008 and 2009. The total duration
of the observations was 233 h. We clearly detected two oscillations with
periods of 465.48493\pm0.00007$ and 488.61822\pm0.00009 s, which may be the
white dwarf spin period and the orbital sideband. The semi-amplitudes of the
oscillations are 25 and 20 mmag, accordingly. The oscillation with a period of
465.48493 s has a stable smooth asymmetric pulse profile whereas the pulse
profile of the oscillation with a period of 488.61822 s reveals significant
changes from a quasi-sinusoidal shape to a shape somewhat resembling a
light-curve of an eclipsing binary. Two detected oscillations imply an orbital
period of 2.73 h. V515 And is one of the most rapidly spinning intermediate
polars with orbital periods less than 3 h and may be not in spin equilibrium.
This can be proved by future observations. For this purpose we obtained
oscillation ephemerises with a formal shelf life of about 100 yr. (a 1 sigma
confidence level).Comment: 10 pages, 8 figures, will be published in MNRA
Secular changes in the quiescence of WZ Sge: the development of a cavity in the inner disk
We find a dimming during optical quiescence of the cataclysmic variable WZ
Sge by about half a magnitude between superoutbursts. We connect the dimming
with the development of a cavity in the inner part of the accretion disk. We
suggest that, when the cavity is big enough, accretion of material is governed
by the magnetic field of the white dwarf and pulsations from the weakly
magnetic white dwarf appear. The time scale of forming the cavity is about a
decade, and it persists throughout the whole quiescent phase. Such a cavity can
be accommodated well by the proposed magnetic propeller model for WZ Sge, where
during quiescence mass is being expelled by the magnetic white dwarf from the
inner regions of the accretion disk to larger radii.Comment: 10 pages, 4 figures, accepted for publication in Astronomy and
Astrophysics; following referee report, many textual changes, figures
improved, more historic data added, conclusions unchange
2015 ACVIM Small Animal Consensus Statement on Seizure Management in Dogs
This report represents a scientific and working clinical consensus statement on seizure management in dogs based on current literature and clinical expertise. The goal was to establish guidelines for a predetermined, concise, and logical sequential approach to chronic seizure management starting with seizure identification and diagnosis (not included in this report), reviewing decision‐making, treatment strategies, focusing on issues related to chronic antiepileptic drug treatment response and monitoring, and guidelines to enhance patient response and quality of life. Ultimately, we hope to provide a foundation for ongoing and future clinical epilepsy research in veterinary medicine
Preliminary results using a P300 brain-computer interface speller: a possible interaction effect between presentation paradigm and set of stimuli
Fernández-Rodríguez Á., Medina-Juliá M.T., Velasco-Álvarez F., Ron-Angevin R. (2019) Preliminary Results Using a P300 Brain-Computer Interface Speller: A Possible Interaction Effect Between Presentation Paradigm and Set of Stimuli. In: Rojas I., Joya G., Catala A. (eds) Advances in Computational Intelligence. IWANN 2019. Lecture Notes in Computer Science, vol 11506. Springer, ChamSeveral proposals to improve the performance controlling a P300-based BCI speller have been studied using the standard row-column presentation (RCP) par-adigm. However, this paradigm could not be suitable for those patients with lack of gaze control. To solve that, the rapid serial visual presentation (RSVP) para-digm, which presents the stimuli located in the same position, has been proposed in previous studies. Thus, the aim of the present work is to assess if a stimuli set of pictures that improves the performance in RCP, could also improve the per-formance in a RSVP paradigm. Six participants have controlled four conditions in a calibration task: letters in RCP, pictures in RCP, letters in RSVP and pictures in RSVP. The results showed that pictures in RCP obtained the best accuracy and information transfer rate. The improvement effect given by pictures was greater in the RCP paradigm than in RSVP. Therefore, the improvements reached under RCP may not be directly transferred to the RSVP.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
The Formation and Evolution of Virgo Cluster Galaxies - I. Broadband Optical & Infrared Colours
We use a combination of deep optical (gri) and near-infrared (H) photometry
to study the radially-resolved colours of a broad sample of 300 Virgo cluster
galaxies. For most galaxy types, we find that the median g-H colour gradient is
either flat (gas-poor giants and gas-rich dwarfs) or negative (i.e., colours
become bluer with increasing radius; gas-poor dwarfs, spirals, and gas-poor
peculiars). Later-type galaxies typically exhibit more negative gradients than
early-types. Given the lack of a correlation between the central colours and
axis ratios of Virgo spiral galaxies, we argue that dust likely plays a small
role, if at all, in setting those colour gradients. We search for possible
correlations between galaxy colour and photometric structure or environment and
find that the Virgo galaxy colours become redder with increasing concentration,
luminosity and surface brightness, while no dependence with cluster-centric
radius or local galaxy density is detected (over a range of ~2 Mpc and ~3-16
Mpc^-2, respectively). However, the colours of gas-rich Virgo galaxies do
correlate with neutral gas deficiency, such that these galaxies become redder
with higher deficiencies. Comparisons with stellar population models suggest
that these colour gradients arise principally from variations in stellar
metallicity within these galaxies, while age variations only make a significant
contribution to the colour gradients of Virgo irregulars. A detailed stellar
population analysis based on this material is presented in Roediger et al
(2011b; arXiv:1011.3511).Comment: 34 pages, 12 figures, 1 table, submitted to MNRAS; Paper II
(arXiv:1011.3511) has also been update
The ``Outside-In'' Outburst of HT Cassiopeiae
We present results from photometric observations of the dwarf nova system HT
Cas during the eruption of November 1995. The data include the first
two--colour observations of an eclipse on the rise to outburst. They show that
during the rise to outburst the disc deviates significantly from steady state
models, but the inclusion of an inner-disc truncation radius of about 4
and a ``flared'' disc of semi-opening angle of produces
acceptable fits. The disc is found to have expanded at the start of the
outburst to about , as compared to quiescent measurements. The
accretion disc then gradually decreases in radius reaching during
the last stages of the eruption. Quiescent eclipses were also observed prior to
and after the eruption and a revised ephemeris is calculated.Comment: 9 pages, 11 figures, to appear in MNRA
Determination of the basic parameters of the dwarf nova EY Cygni
High-dispersion spectroscopy of EY Cyg obtained from data spanning twelve
years show, for the first time, the radial velocity curves from both emission
and absorption line systems, yielding semi-amplitudes K_{em}=24+/- 4 km s^-1
and K_{abs}=54+/- 2 km s^-1. The orbital period of this system is found to be
0.4593249(1)d. The masses of the stars, their mass ratio and their separation
are found to be M_1 sin^3 i = 0.015+/-0.002 M_sun, M_2 sin^3 i = 0.007+/-0.002
M_sun, q = K_1/K_2 = M_2/M_1 = 0.44+/-0.02 and a sin i = 0.71+/-0.04 R_sun. We
also found that the spectral type of the secondary star is around K0,consistent
with an early determination by Kraft(1962). From the spectral type of the
secondary star and simple comparisons with single main sequence stars, we
conclude that the radius of the secondary star is about 30 per cent larger than
a main sequence star of the same mass. We also present VRI CCD photometric
observations, some of them simultaneous with the spectroscopic runs. The
photometric data shows several light modulations, including a sinusoidal
behaviour with twice the frequency of the orbital period, characteristic of the
modulation coming from an elongated, irradiated secondary star. Low and high
states during quiescence are also detected and discussed. From several
constrains, we obtain tight limits for the inclination angle of the binary
system between 13 and 15 degrees, with a best value of 14 degrees obtained from
the sinusoidal light curve analysis. From the above results we derive masses
M_1 = 1.10+/-0.09 M_sun, M_2 = 0.49+/-0.09 M_sun, and a binary separation a =
2.9+/- 0.1 R_sun.Comment: 14 pages, 14 figures, accepted for publication on A&
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