4,188 research outputs found
Beluga, Delphinapterus leucas, Group Sizes in Cook Inlet, Alaska, Based on Observer Counts and Aerial Video
Belugas, Delphinapterus leucas, groups were videotaped concurrent to observer counts during annual NMFS aerial surveys of Cook Inlet, Alaska, from 1994 to 2000. The videotapes provided permanent records of whale groups that could be examined and compared to group size estimates ade by aerial observers.Examination of the video recordings resulted in 275 counts of 79 whale groups. The McLaren formula was used to account for whales missed while they were underwater (average correction factor 2.03; SD=0.64). A correction for whales missed due to video resolution was developed by using a second, paired video camera that magnified images relative to the standard video. This analysis showed that some whales were missed either because their image size fell below the resolution of hte standard video recording or because two whales surfaced so close to each other that their images appeared to be one large whale. The correction method that resulted depended on knowing the average whale image size in the videotapes. Image sizes were measured for 2,775 whales from 275 different passes over whale groups. Corrected group sizes were calcualted as the product of the original count from video, the correction factor for whales missed underwater, and the correction factor for whales missed due to video resolution (averaged 1.17; SD=0.06). A regression formula was developed to estimate group sizes from aerial observer counts; independent variables were the aerial counts and an interaction term relative to encounter rate (whales per second during the counting of a group), which were regressed against the respective group sizes as calculated from the videotapes. Significant effects of encounter rate, either positive or negative, were found for several observers. This formula was used to estimate group size when video was not available. The estimated group sizes were used in the annual abundance estimates
The precipitation of energetic heavy ions into the upper atmosphere of Jupiter
Evidence for auroral particle precipitation at Jupiter was provided by the ultraviolet spectrometers onboard the Voyagers 1 and 2 spacecraft and by the International Ultraviolet Explorer (IUE). Magnetospheric measurements made by instruments onboard the Voyager spacecraft show that energetic sulfur and oxygen ions are precipitating into the upper atmosphere of Jupiter. A theoretical model has been constructed describing the interaction of precipitating oxygen with the Jovian atmosphere. The auroral energy is deposited in the atmosphere by means of ionization, excitation, and dissociation and heating of the atmospheric gas. Energetic ion and electron precipitation are shown to have similar effects on the atmosphere and ionosphere of Jupiter
Superthermal electron processes in the upper atmosphere of Uranus: Aurora and electroglow
Strong ultraviolet emissions from the upper atmosphere of Uranus suggest that both auroral and electroglow phenomena are of significant aeronomical consequences in the structure of the upper atmosphere. Combined modeling and data analysis were performed to determine the effect of electroglow and auroral phenomena on the global heat and atomic hydrogen budgets in the Uranus upper atmosphere. The results indicate that the auroral and electroglow heat sources are not adequate to explain the high exospheric temperature observed at Uranus, but that the atomic hydrogen supplied by these processes is more than sufficient to explain the observations. The various superthermal electron distributions modeled have significantly different efficiencies for the various processes such as UV emission, heating, ionization, and atomic hydrogen production, and produce quite different H2 band spectra. However, additional information on the UV spectra and global parameters is needed before modeling can be used to distinguish between the possible mechanisms for electroglow
Yosemite Conference on Ionospheric Plasma in the Magnetosphere: Sources, Mechanisms and Consequences, meeting report
The sixth biennial Yosemite topical conference and the first as a Chapman Conference was held on February 3 to 6, 1986. Due to the recent changes in our perception of the dynamics of the ionospheric/magnetospheric system, it was deemed timely to bring researchers together to discuss and contrast the relative importance of solar versus terrestrial sources of magnetospheric plasma. Although the solar wind was once thought to dominate the supply of plasma in the Earth's magnetosphere, it is now thought that the Earth's ionosphere is a significant contributor. Polar wind and other large volume outflows of plasma have been seen at relatively high altitudes over the polar cap and are now being correlated with outflows found in the magnetotail. The auroral ion fountain and cleft ion fountain are examples of ionospheric sources of plasma in the magnetosphere, observed by the Dynamics Explorer 1 (DE 1) spacecraft. The conference was organized into six sessions: four consisting of prepared oral presentations, one poster session, and one session for open forum discussion. The first three oral sessions dealt separately with the three major topics of the conference, i.e., the sources, mechanisms, and consequences of ionospheric plasma in the magnetosphere. A special session of invited oral presentations was held to discuss extraterrestrial ionospheric/magnetospheric plasma processes. The poster session was extended over two evenings during which presenters discussed their papers on a one-on-one basis. The last session of the conferences was reserved for open discussions of those topics or ideas considered most interesting or controversial
Evaluation of aircraft microwave data for locating zones for well stimulation and enhanced gas recovery
Imaging radar was evaluated as an adjunct to conventional petroleum exploration techniques, especially linear mapping. Linear features were mapped from several remote sensor data sources including stereo photography, enhanced LANDSAT imagery, SLAR radar imagery, enhanced SAR radar imagery, and SAR radar/LANDSAT combinations. Linear feature maps were compared with surface joint data, subsurface and geophysical data, and gas production in the Arkansas part of the Arkoma basin. The best LANDSAT enhanced product for linear detection was found to be a winter scene, band 7, uniform distribution stretch. Of the individual SAR data products, the VH (cross polarized) SAR radar mosaic provides for detection of most linears; however, none of the SAR enhancements is significantly better than the others. Radar/LANDSAT merges may provide better linear detection than a single sensor mapping mode, but because of operator variability, the results are inconclusive. Radar/LANDSAT combinations appear promising as an optimum linear mapping technique, if the advantages and disadvantages of each remote sensor are considered
A protosolar nebula origin for the ices agglomerated by Comet 67P/Churyumov-Gerasimenko
The nature of the icy material accreted by comets during their formation in
the outer regions of the protosolar nebula is a major open question in
planetary science. Some scenarios of comet formation predict that these bodies
agglomerated from crystalline ices condensed in the protosolar nebula.
Concurrently, alternative scenarios suggest that comets accreted amorphous ice
originating from the interstellar cloud or from the very distant regions of the
protosolar nebula. On the basis of existing laboratory and modeling data, we
find that the N/CO and Ar/CO ratios measured in the coma of the Jupiter
family comet 67P/Churyumov-Gerasimenko by the ROSINA instrument aboard the
European Space Agency's Rosetta spacecraft match those predicted for gases
trapped in clathrates. If these measurements are representative of the bulk
N/CO and Ar/CO ratios in 67P/Churyumov-Gerasimenko, it implies that the
ices accreted by the comet formed in the nebula and do not originate from the
interstellar medium, supporting the idea that the building blocks of outer
solar system bodies have been formed from clathrates and possibly from pure
crystalline ices. Moreover, because 67P/Churyumov-Gerasimenko is impoverished
in Ar and N, the volatile enrichments observed in Jupiter's atmosphere
cannot be explained solely via the accretion of building blocks with similar
compositions and require an additional delivery source. A potential source may
be the accretion of gas from the nebula that has been progressively enriched in
heavy elements due to photoevaporation.Comment: The Astrophysical Journal Letters, in pres
Winds of Planet Hosting Stars
The field of exoplanetary science is one of the most rapidly growing areas of
astrophysical research. As more planets are discovered around other stars, new
techniques have been developed that have allowed astronomers to begin to
characterise them. Two of the most important factors in understanding the
evolution of these planets, and potentially determining whether they are
habitable, are the behaviour of the winds of the host star and the way in which
they interact with the planet. The purpose of this project is to reconstruct
the magnetic fields of planet hosting stars from spectropolarimetric
observations, and to use these magnetic field maps to inform simulations of the
stellar winds in those systems using the Block Adaptive Tree Solar-wind Roe
Upwind Scheme (BATS-R-US) code. The BATS-R-US code was originally written to
investigate the behaviour of the Solar wind, and so has been altered to be used
in the context of other stellar systems. These simulations will give
information about the velocity, pressure and density of the wind outward from
the host star. They will also allow us to determine what influence the winds
will have on the space weather environment of the planet. This paper presents
the preliminary results of these simulations for the star Bo\"otis,
using a newly reconstructed magnetic field map based on previously published
observations. These simulations show interesting structures in the wind
velocity around the star, consistent with the complex topology of its magnetic
field.Comment: 8 pages, 2 figures, accepted for publication in the peer-reviewed
proceedings of the 14th Australian Space Research Conference, held at the
University of South Australia, 29th September - 1st October 201
Discovery of the magnetic field of the B1/B2V star \sigma Lupi
In our search for new magnetic massive stars we use the strongest indirect
indicator of a magnetic field in B stars, which is periodic variability of UV
stellar wind lines occurring in a velocity range symmetric around zero. Our aim
is to obtain follow-up spectropolarimetry to search for a magnetic field in
magnetic candidate stars. We quantify UV wind line variability, and analyse its
time behaviour. The B1/B2V star sigma Lup emerged as a new magnetic candidate
star. AAT spectropolarimetric measurements with SEMPOL were obtained.
The stellar wind line variations of sigma Lup are similar to what is known in
magnetic B stars, but no periodicity could be determined. We detected a
longitudinal magnetic field with varying strength and amplitude of about 100 G
with error bars of typically 20 G, which supports an oblique magnetic-rotator
configuration. The equivalent width variations of the UV lines, the magnetic
and the optical line variations are consistent with the well-known photometric
period of 3.02 days, which we identify with the rotation period of the star.
Additional observations with ESPaDOnS at CFHT strongly confirmed this
discovery, and allowed to determine a precise magnetic period. Further analysis
revealed that Lupi is a helium-strong star, with an enhanced nitrogen
abundance and an underabundance of carbon, and has a spotted surface.
We conclude that sigma Lup is a magnetic oblique rotator, and is a He-strong
star. It is the 4th B star for which a magnetic field is discovered from
studying only its wind variability. Like in the other magnetic B stars the wind
emission originates in the magnetic equator, with maximum emission occurring
when a magnetic pole points towards the Earth. The 3.02 d magnetic rotation
period is consistent with the photometric period, with maximum light
corresponding to maximum magnetic field. A full paper will be submitted to A&A.Comment: 4 pages, 5 figures, to appear in proceedings with AIP. Stellar
polarimetry: From birth to death, Eds. Jennifer Hoffman, Barb Whitney, and
Jon Bjorkma
The impact of LASPO on routes to justice
This research underlines the emotional, social, financial and mental health impacts
for individuals who have attempted to resolve their legal problems without legal aid,
following the implementation of the Legal Aid, Sentencing and Punishment of
Offenders Act (LASPO) in 2013.
LASPO introduced funding cuts to legal aid and narrowed the scope and financial
eligibility criteria, with the result that fewer people could access legal advice and
representation for problems in areas such as family, employment and welfare
benefits law. We interviewed over 100 people in the Liverpool City Region, with
problems in at least one of these areas of law, to understand how LASPO had
affected their options for resolving those issues. We also interviewed a number of
advice providers and legal aid practitioners, and analysed national data from Citizens
Advice.
Many participants reported significant financial deprivation as a result of trying but
not being able to resolve their legal issues. Some were unable to afford food,
adequate housing or other essentials. A lack of preventive legal help led to delays in
resolution, which often made problems worse. There was also evidence that costs
were passed to other parts of the public sector, including an increased reliance on
welfare benefits as a result of unresolved employment issues.
Family law
• The high cost of legal fees is a key barrier to justice. Some participants who
paid for legal advice or representation reported going into debt as a result.
• People’s inability to pay for expert or specialist evidence without legal aid may
have led to courts making decisions on the basis of insufficient information.
• Cuts to legal aid have had a negative impact on children’s lives, especially in
relation to child contact cases.
Employment law
• The main barriers to justice are the high cost of legal representation, the
difficulty of navigating the tribunal process without support and a low level of
knowledge about employment rights.
• Many participants reported that the costs of bringing their claims to tribunal
were disproportionate to the value of the claims. This deterred them from
bringing claims and made it harder to find a solicitor willing to take their case.
• Participants had fewer options for accessing third-sector specialist advice and
representation. Those participants who went to tribunal had to represent
themselves as a result, and in general they lacked the skills or experience to
do this competently.
Welfare benefits law
• LASPO has significantly reduced the capacity of voluntary sector
organisations to provide welfare law advice. There is almost no specialist
advice left to provide support to appeal benefits decisions.
• The removal of welfare benefits law from the scope of legal aid has
exacerbated the impact of recent welfare reforms, which is likely to have
affected disabled people disproportionately.
Most participants tried multiple routes to resolve a single issue: attempting to resolve
problems on their own, trying to access free advice and taking steps to get paid
advice or representation before courts or tribunals. But without legal aid, almost all
the participants struggled to solve their problems
- …