7,833 research outputs found
Measurement of the Nodal Precession of WASP-33 b via Doppler Tomography
We have analyzed new and archival time series spectra taken six years apart
during transits of the hot Jupiter WASP-33 b, and spectroscopically resolved
the line profile perturbation caused by the Rossiter-McLaughlin effect. The
motion of this line profile perturbation is determined by the path of the
planet across the stellar disk, which we show to have changed between the two
epochs due to nodal precession of the planetary orbit. We measured rates of
change of the impact parameter and the sky-projected spin-orbit misalignment of
yr and
~ yr, respectively,
corresponding to a rate of nodal precession of
~ yr. This is only the
second measurement of nodal precession for a confirmed exoplanet transiting a
single star. Finally, we used the rate of precession to set limits on the
stellar gravitational quadrupole moment of
.Comment: Published in ApJL. 5 pages, 3 figures. Corrected error in the
calculation of J_
Seasonal Dynamics of Mesodinium rubrum in Chesapeake Bay
The photosynthetic ciliate Mesodinium rubrum is a common member of coastal phytoplankton communities that is well adapted to low-light, turbid ecosystems. It supports the growth of, or competes with, harmful dinoflagellate species for cryptophyte prey, as well as being a trophic link to copepods and larval fish. We have compiled data from various sources (n = 1063), on the abundance and distribution of M. rubrum in Chesapeake Bay and its tributaries. Because M. rubrum relies on obtaining organelles from cryptophyte algae to maintain rapid growth, we also enumerated cryptophyte algae in the portion of these samples that we collected (n =386). Mesodinium rubrum occurred in oligohaline to polyhaline regions of Chesapeake Bay and throughout the year. Blooms (\u3e100 cells mL-1) primarily occurred during spring, followed by autumn. When compared across all seasons, M. rubrum abundance was positively correlated to temperature and cryptophytes, and negatively correlated with salinity. However, more focused analyses revealed that M. rubrum abundance during spring was associated with surface layer warming and decreased salinity, while early autumn assemblages were associated with surface cooling. These results imply that there are distinct seasonal niches for M. rubrum blooms. Blooms were more common in tributaries than in the main stem Bay and tended to be restricted to salinities under 10 PSU. Despite the rarity of red water events, M. rubrum is a ubiquitous mixotroph in Chesapeake Bay and at times likely exerts a strong influence on cryptophyte algal abundance and hence planktonic food web structure
Life-Cycle Impacts of Forest Resource Activities in the Pacific Northwest and Southeast United States
A more intensive management alternative was created for each region by reallocating acres to higher management intensity classes. Harvesting activities were segmented into five stages to allow development of all inputs and outputs: (1) felling, (2) processing (bucking, limbing, cutting to length), (3) secondary transportation (skidding and yarding), (4) loading, and (5) hauling to a process point. The costs and consumption rates of energy and materials for these activities drove the log outputs, emissions, and carbon pools. Logs are allocated to wood product facilities, the primary product of the analysis, or pulp and paper mills as a co-product from the forest. Non-merchantable slash is generally left on site and is disposed of through site preparation activities. Transportation-related activities and the required diesel fuel produce by far the largest contribution to emission outputs. However, fertilizer use contributes to much of the change in emissions as acreage shifts to higher intensity management alternatives
Baseline characteristics of patients with and without hypercoaguable sepsis and the effect of afelimomab on mortality: a post hoc analysis from the MONARCS trial
Hearing and dementia: from ears to brain
The association between hearing impairment and dementia has emerged as a major public health challenge, with significant opportunities for earlier diagnosis, treatment and prevention. However, the nature of this association has not been defined. We hear with
our brains, particularly within the complex soundscapes of everyday life: neurodegenerative pathologies target the auditory brain,
and are therefore predicted to damage hearing function early and profoundly. Here we present evidence for this proposition, based
on structural and functional features of auditory brain organization that confer vulnerability to neurodegeneration, the extensive,
reciprocal interplay between ‘peripheral’ and ‘central’ hearing dysfunction, and recently characterized auditory signatures of canonical neurodegenerative dementias (Alzheimer’s disease, Lewy body disease and frontotemporal dementia). Moving beyond any simple dichotomy of ear and brain, we argue for a reappraisal of the role of auditory cognitive dysfunction and the critical coupling of
brain to peripheral organs of hearing in the dementias. We call for a clinical assessment of real-world hearing in these diseases that
moves beyond pure tone perception to the development of novel auditory ‘cognitive stress tests’ and proximity markers for the
early diagnosis of dementia and management strategies that harness retained auditory plasticit
Experiences of using mobile technologies and virtual field tours in Physical Geography: implications for hydrology education
Education in hydrology is changing rapidly due to diversification of students, emergent major scientific and practical challenges that our discipline must engage with, shifting pedagogic ideas and higher education environments, the need for students to develop new discipline specific and transferrable skills, and the advent of innovative technologies for learning and teaching. This paper focuses on new technologies in the context of learning and teaching in Physical Geography and reflects on the implications of our experiences for education in hydrology. We evaluate the experience of designing and trialling novel mobile technology-based field exercises and a virtual field tour for a Year 1 undergraduate Physical Geography module at a UK university. The new exercises are based on using and obtaining spatial data, operation of meteorological equipment (explained using an interactive DVD), and include introductions to global positioning systems (GPS) and geographical information systems (GIS). The technology and exercises were well received in a pilot study and subsequent rolling-out to the full student cohort (∼150 students). A statistically significant improvement in marks was observed following the redesign. Although the students enjoyed using mobile technology, the increased interactivity and opportunity for peer learning were considered to be the primary benefits by students. This is reinforced further by student preference for the new interactive virtual field tour over the previous "show-and-tell" field exercise. Despite the new exercises having many advantages, exercise development was not trivial due to the high start-up costs, the need for provision of sufficient technical support and the relative difficulty of making year-to-year changes (to the virtual field tour in particular). Our experiences are highly relevant to the implementation of novel learning and teaching technologies in hydrology education
A Review of NASA's Radiation-Hardened Electronics for Space Environments Project
NASA's Radiation Hardened Electronics for Space Exploration (RHESE) project develops the advanced technologies required to produce radiation hardened electronics, processors, and devices in support of the requirements of NASA's Constellation program. Over the past year, multiple advancements have been made within each of the RHESE technology development tasks that will facilitate the success of the Constellation program elements. This paper provides a brief review of these advancements, discusses their application to Constellation projects, and addresses the plans for the coming year
Diagnosis of prediabetes in cats: glucose concentration cut points for impaired fasting glucose and impaired glucose tolerance
Diabetes is typically diagnosed in cats once clinical signs are evident. Diagnostic criteria for prediabetes in cats have not been defined. The objective of the study was to establish methodology and cut points for fasting and 2-h blood glucose concentrations in healthy client-owned senior cats (≥8 yr) using ear/paw samples and a portable glucose meter calibrated for feline blood. Of the 78 cats, 27 were ideal (body condition score [BCS] 4 or 5 of 9), 31 overweight (BCS 6 or 7), and 20 obese (BCS 8 or 9); 19 were Burmese and 59 non-Burmese. After an 18–24-h fast and an ear/paw blood glucose measurement using a portable glucose meter, glucose (0.5 g/kg bodyweight) was administered intravenous and blood glucose measured at 2 min and 2 h. Cut points for fasting and 2-h glucose concentrations were defined as the upper limits of 95% reference intervals using cats with BCS 4 or 5. The upper cut point for fasting glucose was 6.5 mmol/L. Of the overweight and obese cats, 1 (BCS 7) was above this cut point indicating evidence of impaired fasting glucose. The cut point for 2-h glucose was 9.8 mmol/L. A total of 7 cats (4 with BCS 8 or 9 including 1 Burmese; 3 with BCS 6 or 7, non-Burmese) were above this cut point and thus had evidence of impaired glucose tolerance. In conclusion, the methodology and cutpoints for diagnosis of prediabetes are defined for use in healthy cats 8 yr and older with a range of BCSs
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