923 research outputs found
Line and continuum radiative transfer modelling of AA Tau
We present photometric and spectroscopic models of the Classical T Tauri star
AA Tau. Photometric and spectroscopic variability present in observations of AA
Tau is attributed to a magnetically induced warp in the accretion disc,
periodically occulting the photosphere on an 8.2--day timescale. Emission line
profiles show signatures of both infall, attributed to magnetospherically
accreting material, and outflow. Using the radiative transfer code TORUS, we
have investigated the geometry and kinematics of AA Tau's circumstellar disc
and outflow, which is modelled here as a disc wind. Photometric models have
been used to constrain the aspect ratio of the disc, the offset angle of the
magnetosphere dipole with respect to the stellar rotation axis, and the inner
radius of the circumstellar disc. Spectroscopic models have been used to
constrain the wind and magnetosphere temperatures, wind acceleration parameter,
and mass loss rate. We find observations are best fitted by models with a mass
accretion rate of M yr, a dipole offset of
between and , a magnetosphere that truncates the disc from
5.2 to 8.8 R, a mass-loss-rate to accretion-rate ratio of ~ 0.1, a
magnetosphere temperature of 8500 -- 9000 K, and a disc wind temperature of
8000 K.Comment: 22 pages, 32 figures, 4 tables. Accepted by MNRAS. V3: Corrected typ
Introducing Diagnosis-Related Groups in Kazakhstan: Evolution, achievements, and challenges.
In 2012, Kazakhstan introduced Diagnosis-Related Groups (DRGs), as part of a package of reforms which sought to contain costs and to improve efficiency and transparency in the health system; but the main challenge was to design and implement a DRG system in just one year. In 2011-2012, Kazakhstan developed its own DRG system. Initially 180 DRGs were defined to group inpatient cases but this number was subsequently expanded to more than 400. Because of time limits, the cost weights had to be derived in the absence of existing standard hospital cost accounting systems, and a national patient data transfer system also needed developing. Most importantly, huge efforts were needed to develop a regulatory framework and build up DRG capabilities at a national level. The implementation of DRGs was facilitated by strong political will for their introduction as part of a coherent package of health reforms, and consolidated efforts to build capacity. DRGs are now the key payment mechanism for hospitals. However the reforms are not fully institutionalized: the DRG structure is continuously being refined in a context of data limitations, and the revision of cost weights is most affected by insufficient data and the lack of standardized reporting mechanisms. Capacity around DRG coding is also still being developed. Countries planning to introduce DRG systems should be aware of the challenges in moving too quickly to implement DRGs as the main hospital reimbursement mechanism
First record of Solomons Nightjar Eurostopodus nigripennis for Malaita, with a description of its nest site
Solomons Nightjar Eurostopodus nigripennis, listed as Vulnerable by BirdLife International, has previously been recorded only from the north and central Solomon Islands. Even within the species' known range there are few records, limiting knowledge of its ecology. We provide photographic evidence of a Solomons Nightjar nest in a streambed on the island of Malaita at an altitude of c.270 m - the first record on this large island. This observation, combined with traditional local knowledge, suggests that the species may have a wider range of nesting habitat than previously documented, and that further surveys in collaboration with local tribespeople could be important for conservation efforts
Similarity theory and calculation of turbulent fluxes at the surface for the stably stratified atmospheric boundary layers
In this paper we revise the similarity theory for the stably stratified
atmospheric boundary layer (ABL), formulate analytical approximations for the
wind velocity and potential temperature profiles over the entire ABL, validate
them against large-eddy simulation and observational data, and develop an
improved surface flux calculation technique for use in operational models.Comment: The submission to a special issue of the Boundary-Layer Meteorology
devoted to the NATO advanced research workshop Atmospheric Boundary Layers:
Modelling and Applications for Environmental Securit
Impact of ivermectin administered for scabies treatment on the prevalence of head lice in Atoifi, Solomon Islands.
Scabies and head lice are ubiquitous ectoparasitic infestations that are common across the Pacific Islands. Ivermectin is an effective treatment for both conditions, although the doses used vary. At a community level, mass drug administration (MDA) with ivermectin is an effective strategy to decrease prevalence of scabies. To what extent MDA with ivermectin will also reduce prevalence of head lice is unknown.
Head lice prevalence was assessed before and after MDA with oral ivermectin (at a dose of 200 micrograms per kilogram of body weight) administered on day 1 and day 8. The primary outcome was the change in prevalence of head louse infestation at two weeks compared to baseline. Longer term efficacy was assessed three months after MDA.
118 participants were enrolled. Baseline prevalence of active head louse infestation was 25.4% (95% CI 18.4-34.0). At three-month follow-up, prevalence was 7.5% (95% CI 2.7-12.3), a relative reduction of 70.6% (95% CI 72.7%-91.4%, p <0.001). Head louse infestation was associated with younger age (age ≤10 years: prevalence 46.7%; adjusted odds ratio compared to adults of 7.2, 95%CI 2.0-25.9) and with having at least one other member of the household with active head louse infestation (adjusted odds ratio 4.3, 95%CI 1.7-11.1).
Head louse infestation is common in the Solomon Islands. This proof of principle study shows that oral ivermectin at a dose of 200 micrograms per kilogram can reduce the burden of active head louse infestation, offering an additional collateral benefit of MDA with ivermectin for scabies control.
ClinicalTrials.gov NCT03236168
Low topotype diversity of recent foot-and-mouth disease virus serotypes O and A from districts located along the Uganda and Tanzania border
Foot-and-mouth disease (FMD) is one of the most important livestock diseases in East Africa with outbreaks reported annually that cause severe economic losses. It is possible to control disease using vaccination, but antigenic matching of the vaccine to circulating strains is critical. To determine the relationship between foot-and-mouth disease viruses circulating in districts along the Uganda and Tanzanian border between 2016 and 2017 and currently used vaccines, phylogenetic analysis of the full VP1 virus sequences was carried out on samples collected from both sides of the border. A total of 43 clinical samples were collected from animals exhibiting signs of FMD and VP1 sequences generated from 11 of them. Eight out of the 11 sequences obtained belonged to serotype O and three belonged to serotype A. The serotype O sequences obtained showed limited nucleotide divergence (average of 4.9%) and belonged to topotype East Africa-2, whereas the most common O-type vaccine strain used in the region (O/KEN/77/78) belonged to East Africa-1. The serotype A viruses belonged to topotype Africa-G1 (average nucleotide divergence 7.4%), as did vaccine strain K5/1980. However, vaccine strain K35/1980 belonged to Africa G VII with an average sequence divergence of 20.5% from the study sequences. The genetic distances between current vaccine strains and circulating field strains underscores the crucial need for regular vaccine matching and the importance of collaborative efforts for better control of FMD along this border area
When the path is never shortest: a reality check on shortest path biocomputation
Shortest path problems are a touchstone for evaluating the computing
performance and functional range of novel computing substrates. Much has been
published in recent years regarding the use of biocomputers to solve minimal
path problems such as route optimisation and labyrinth navigation, but their
outputs are typically difficult to reproduce and somewhat abstract in nature,
suggesting that both experimental design and analysis in the field require
standardising. This chapter details laboratory experimental data which probe
the path finding process in two single-celled protistic model organisms,
Physarum polycephalum and Paramecium caudatum, comprising a shortest path
problem and labyrinth navigation, respectively. The results presented
illustrate several of the key difficulties that are encountered in categorising
biological behaviours in the language of computing, including biological
variability, non-halting operations and adverse reactions to experimental
stimuli. It is concluded that neither organism examined are able to efficiently
or reproducibly solve shortest path problems in the specific experimental
conditions that were tested. Data presented are contextualised with biological
theory and design principles for maximising the usefulness of experimental
biocomputer prototypes.Comment: To appear in: Adamatzky, A (Ed.) Shortest path solvers. From software
to wetware. Springer, 201
Energy- and flux-budget (EFB) turbulence closure model for the stably stratified flows. Part I: Steady-state, homogeneous regimes
We propose a new turbulence closure model based on the budget equations for
the key second moments: turbulent kinetic and potential energies: TKE and TPE
(comprising the turbulent total energy: TTE = TKE + TPE) and vertical turbulent
fluxes of momentum and buoyancy (proportional to potential temperature).
Besides the concept of TTE, we take into account the non-gradient correction to
the traditional buoyancy flux formulation. The proposed model grants the
existence of turbulence at any gradient Richardson number, Ri. Instead of its
critical value separating - as usually assumed - the turbulent and the laminar
regimes, it reveals a transition interval, 0.1< Ri <1, which separates two
regimes of essentially different nature but both turbulent: strong turbulence
at Ri<<1; and weak turbulence, capable of transporting momentum but much less
efficient in transporting heat, at Ri>1. Predictions from this model are
consistent with available data from atmospheric and lab experiments, direct
numerical simulation (DNS) and large-eddy simulation (LES).Comment: 40 pages, 6 figures, Boundary-layer Meteorology, resubmitted, revised
versio
High Latitude Dynamics of Atmosphere-Ice-Ocean Interactions
Dynamics of atmosphere–ice–ocean interactions in the high latitudes. What: Scientists from 13 countries involved with modeling and observing the coupled high-latitude weather and climate system discussed our current understanding and challenges in polar prediction, extreme events, and coupled processes on scales ranging from cloud and turbulent processes, from micrometers and a few hundred meters to processes on synoptic-scale weather phenomena and pan-Arctic energy budgets of hundreds to thousands of kilometers. Workshop participants also evaluated research needs to improve numerical models with usages spanning from uncoupled to fully coupled models used for weather and climate prediction (http://highlatdynamics.b.uib.no/). When: 23–27 March 2015. Where: Rosendal, Norwa
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