1,072 research outputs found
Oceanographic Structure and Light Levels Drive Patterns of Sound Scattering Layers in a Low-Latitude Oceanic System
Several factors have been reported to structure the spatial and temporal patterns of sound scattering layers, including temperature, oxygen, salinity, light, and physical oceanographic conditions. In this study, we examined the spatiotemporal variability of acoustically detected sound scattering layers in the northern Gulf of Mexico to investigate the drivers of this variability, including mesoscale oceanographic features [e.g., Loop Current-origin water (LCOW), frontal boundaries, and Gulf Common Water]. Results indicate correlations in the vertical position and acoustic backscatter intensity of sound scattering layers with oceanographic conditions and light intensity. LCOW regions displayed consistent decreases, by a factor of two and four, in acoustic backscatter intensity in the upper 200 m relative to frontal boundaries and Gulf Common Water, respectively. Sound scattering layers had greater backscatter intensity at night in comparison to daytime (25x for frontal boundaries, 17x for LCOW, and 12x for Gulf Common Water). The importance of biotic (primary productivity) and abiotic (sea surface temperature, salinity) factors varied across oceanographic conditions and depth intervals, suggesting that the patterns in distribution and behavior of mesopelagic assemblages in low-latitude, oligotrophic ecosystems can be highly dynamic
Patterns of Human Herpesvirus-8 Oral Shedding among Diverse Cohorts of Human Herpesvirus-8 Seropositive Persons
Human herpesvirus-8 (HHV-8), the etiologic agent of Kaposi sarcoma (KS), establishes lifelong latent infection with periodic lytic replication (âsheddingâ) at mucosal sites, especially the oropharynx. Patterns of HHV-8 shedding are not well understood, and require elucidation to better predict risk of HHV-8 related malignancies in those infected. We sought to characterize patterns of HHV-8 oropharyngeal shedding among diverse cohorts that enrolled HHV-8 seropositive persons
The evolution of substructure II: linking dynamics to environment
We present results from a series of high-resolution N-body simulations that
focus on the formation and evolution of eight dark matter halos, each of order
a million particles within the virial radius. We follow the time evolution of
hundreds of satellite galaxies with unprecedented time resolution, relating
their physical properties to the differing halo environmental conditions. The
self-consistent cosmological framework in which our analysis was undertaken
allows us to explore satellite disruption within live host potentials, a
natural complement to earlier work conducted within static potentials. Our host
halos were chosen to sample a variety of formation histories, ages, and
triaxialities; despite their obvious differences, we find striking similarities
within the associated substructure populations. Namely, all satellite orbits
follow nearly the same eccentricity distribution with a correlation between
eccentricity and pericentre. We also find that the destruction rate of the
substructure population is nearly independent of the mass, age, and triaxiality
of the host halo. There are, however, subtle differences in the velocity
anisotropy of the satellite distribution. We find that the local velocity bias
at all radii is greater than unity for all halos and this increases as we move
closer to the halo centre, where it varies from 1.1 to 1.4. For the global
velocity bias we find a small but slightly positive bias, although when we
restrict the global velocity bias calculation to satellites that have had at
least one orbit, the bias is essentially removed.Comment: 14 pages, 14 figures, MNRAS in pres
The Commensal Real-time ASKAP Fast Transients (CRAFT) survey
We are developing a purely commensal survey experiment for fast (<5s)
transient radio sources. Short-timescale transients are associated with the
most energetic and brightest single events in the Universe. Our objective is to
cover the enormous volume of transients parameter space made available by
ASKAP, with an unprecedented combination of sensitivity and field of view. Fast
timescale transients open new vistas on the physics of high brightness
temperature emission, extreme states of matter and the physics of strong
gravitational fields. In addition, the detection of extragalactic objects
affords us an entirely new and extremely sensitive probe on the huge reservoir
of baryons present in the IGM. We outline here our approach to the considerable
challenge involved in detecting fast transients, particularly the development
of hardware fast enough to dedisperse and search the ASKAP data stream at or
near real-time rates. Through CRAFT, ASKAP will provide the testbed of many of
the key technologies and survey modes proposed for high time resolution science
with the SKA.Comment: accepted for publication in PAS
The importance of longâterm experiments in agriculture: their management to ensure continued crop production and soil fertility; the Rothamsted experience
Summary Longâterm field experiments that test a range of treatments and are intended to assess the sustainability of crop production, and thus food security, must be managed actively to identify any treatment that is failing to maintain or increase yields. Once identified, carefully considered changes can be made to the treatment or management, and if they are successful yields will change. If suitable changes cannot be made to an experiment to ensure its continued relevance to sustainable crop production, then it should be stopped. Longâterm experiments have many other uses. They provide a field resource and samples for research on plant and soil processes and properties, especially those properties where change occurs slowly and affects soil fertility. Archived samples of all inputs and outputs are an invaluable source of material for future research, and data from current and archived samples can be used to develop models to describe soil and plant processes. Such changes and uses in the Rothamsted experiments are described, and demonstrate that with the appropriate crop, soil and management, acceptable yields can be maintained for many years, with either organic manure or inorganic fertilizers. Highlights Longâterm experiments demonstrate sustainability and increases in crop yield when managed to optimize soil fertility. Shifting individual response curves into coincidence increases understanding of the factors involved. Changes in inorganic and organic pollutants in archived crop and soil samples are related to inputs over time. Models describing soil processes are developed from current and archived soil data
The stellar content of the Hamburg/ESO survey. II. A large, homogeneously-selected sample of high latitude carbon stars
We present a sample of 403 faint high latitude carbon (FHLC) stars selected
from the digitized objective prism plates of the Hamburg/ESO Survey (HES).
Because of the ~15 Angstroem spectral resolution and high signal-to-noise ratio
of the HES prism spectra, our automated procedure based on the detection of C_2
and CN molecular bands permits high-confidence identification of carbon stars
without the need for follow-up spectroscopy. From a set of 329 plates (87% of
the survey), covering 6400 square degrees to a magnitude limit of V~16.5, we
analyze the selection efficiency and effective surface area of the HES FHLC
survey to date. The surface density of FHLC stars that we detect (0.072 +/-
0.005 square degrees) is 2-4 times higher than that of previous objective prism
and CCD surveys at high galactic latitude, even though those surveys claimed a
limiting magnitude up to 1.5 magnitudes fainter. This attests to the highest
selection sensitivity yet achieved for these types of stars.Comment: 8 pages, 6 figures; A&A in pres
Multi-stakeholder consensus on a target product profile for an HIV cure
Developing a cure for HIV is a global priority. Target product profiles are a tool commonly used throughout the drug development process to align interested parties around a clear set of goals or requirements for a potential product. Three distinct therapeutic modalities (combination therapies, ex-vivo gene therapy, and in-vivo gene therapy) for a target product profile for an HIV cure were identified. Using a process of expert face-to-face consultation and an online Delphi consultation, we found a high degree of agreement regarding the criteria for the optimum target product profile. Although the minimum attributes for a cure were debated, the broad consensus was that an acceptable cure need not be as safe and effective as optimally delivered antiretroviral therapy. An intervention that successfully cured a reasonable fraction of adults would be sufficient to advance to the clinic. These target product profiles will require further discussion and ongoing revisions as the field matures
Multi-stakeholder consensus on a target product profile for an HIV cure
Developing a cure for HIV is a global priority. Target product profiles are a tool commonly used throughout the drug development process to align interested parties around a clear set of goals or requirements for a potential product. Three distinct therapeutic modalities (combination therapies, ex-vivo gene therapy, and in-vivo gene therapy) for a target product profile for an HIV cure were identified. Using a process of expert face-to-face consultation and an online Delphi consultation, we found a high degree of agreement regarding the criteria for the optimum target product profile. Although the minimum attributes for a cure were debated, the broad consensus was that an acceptable cure need not be as safe and effective as optimally delivered antiretroviral therapy. An intervention that successfully cured a reasonable fraction of adults would be sufficient to advance to the clinic. These target product profiles will require further discussion and ongoing revisions as the field matures
Towards a grapho-phonologically parsed corpus of medieval Scots:Database design and technical solutions
This paper presents a newly constructed corpus of sound-to-spelling mappings in medieval Scots, which stems from the work of the From Inglis to Scots (FITS) project. We have developed a systematic approach to the relationships between individual spellings and proposed sound values, and recorded these mutual links in a relational database. In this paper, we introduce the theoretical underpinnings of sound-to-spelling and spelling-to-sound mappings, and show how a Scots root morpheme undergoes grapho-phonological parsing, the analytical procedure that is employed to break down spelling sequences into sound units. We explain the data collection and annotation for the FITS Corpus (Alcorn et al., forthcoming), drawing attention to the extensive meta-data which accompany each analysed unit of spelling and sound. The database records grammatical and lexical information about the root, the positional arrangement of segments within the root, labels for the nuclei, vowels and consonants, the morphological context, and extra-linguistic detail of the text a given root was taken from (date, place and text type). With this wealth of information, the FITS corpus is capable of answering complex queries about the sound and spelling systems of medieval Scots. We also suggest how our methodology can be transferred to other non-standardised spelling systems
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