1,647 research outputs found
The progenitor mass of the Type IIP supernova SN 2004et from late-time spectral modeling
SN 2004et is one of the nearest and best-observed Type IIP supernovae, with a
progenitor detection as well as good photometric and spectroscopic
observational coverage well into the nebular phase. Based on nucleosynthesis
from stellar evolution/explosion models we apply spectral modeling to analyze
its 140-700 day evolution from ultraviolet to mid-infrared. We find a M_ZAMS=
15 Msun progenitor star (with an oxygen mass of 0.8 Msun) to satisfactorily
reproduce [O I] 6300, 6364 {\AA} and other emission lines of carbon, sodium,
magnesium, and silicon, while 12 Msun and 19 Msun models under- and overproduce
most of these lines, respectively. This result is in fair agreement with the
mass derived from the progenitor detection, but in disagreement with
hydrodynamical modeling of the early-time light curve. From modeling of the
mid-infrared iron-group emission lines, we determine the density of the
"Ni-bubble" to rho(t) = 7E-14*(t/100d)^-3 g cm^-3, corresponding to a filling
factor of f = 0.15 in the metal core region (V = 1800 km/s). We also confirm
that silicate dust, CO, and SiO emission are all present in the spectra.Comment: 21 pages, 15 figures. Accepted for publication in A&
Mefloquine Is Highly Efficacious against Chloroquine-Resistant \u3ci\u3ePlasmodium vivax\u3c/i\u3e Malaria and \u3ci\u3ePlasmodium falciparum\u3c/i\u3e Malaria in Papua, Indonesia
Background. During the period of 1996–1999, we prospectively monitored 243 Javanese adults and children after arriving in Papua, Indonesia, and microscopically documented each new case of malaria by active surveillance.
Methods. In a randomized, open-label, comparative malaria treatment trial, 72 adults and 50 children received chloroquine for each incident case of malaria, and 74 adults and 47 children received mefloquine.
Results. Among 975 primary treatment courses, the cumulative 28-day curative efficacies were 26% and 82% for chloroquine against Plasmodium falciparum malaria and Plasmodium vivax malaria, respectively. Mefloquine cure rates were far superior (96% against P. falciparum malaria and 99.6% against P. vivax malaria).
Conclusions. Mefloquine is a useful alternative treatment for P. vivax malaria and P. falciparum malaria in areas such as Papua, where chloroquine is still recommended as the first-line therapeutic agent
(4-Hydroxy-3-nitrobenzyl)methylammonium chloride
The title compound, C8H11N2O3
+·Cl−, was synthesized as an intermediate in the development of a new sugar sensor. The structure displays N—H⋯Cl and O—H⋯O hydrogen bonding, as well as weak O—H⋯Cl interactions and π–π stacking (3.298 Å). There are two formula units in the asymmetric unit
Supersolar Ni/Fe production in the Type IIP SN 2012ec
SN 2012ec is a Type IIP supernova (SN) with a progenitor detection and
comprehensive photospheric-phase observational coverage. Here, we present Very
Large Telescope and PESSTO observations of this SN in the nebular phase. We
model the nebular [O I] 6300, 6364 lines and find their strength to suggest a
progenitor main-sequence mass of 13-15 Msun. SN 2012ec is unique among
hydrogen-rich SNe in showing a distinct and unblended line of stable nickel [Ni
II] 7378. This line is produced by 58Ni, a nuclear burning ash whose abundance
is a sensitive tracer of explosive burning conditions. Using spectral synthesis
modelling, we use the relative strengths of [Ni II] 7378 and [Fe II] 7155 (the
progenitor of which is 56Ni) to derive a Ni/Fe production ratio of 0.20pm0.07
(by mass), which is a factor 3.4pm1.2 times the solar value. High production of
stable nickel is confirmed by a strong [Ni II] 1.939 micron line. This is the
third reported case of a core-collapse supernova producing a Ni/Fe ratio far
above the solar value, which has implications for core-collapse explosion
theory and galactic chemical evolution models.Comment: Published versio
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Deep Viewpoints: Scripted Support for the Citizen Curation of Museum Artworks
This paper describes the design and use of Deep Viewpoints, a software platform for eliciting and sharing citizen perspectives associated with museum artworks. The design of the platform is inspired by the process of Slow Looking in which museum visitors are guided to observe artworks and develop their own response. Within Deep Viewpoints, the processes of observing and responding to artworks are guided by a script comprising stages containing artworks, statements, and prompts or questions to which the follower of the script can respond. Scripts are intended for use either in the gallery or remotely. We describe the design of Deep Viewpoints and how it can be used to respond to scripts, view the responses of others and author new scripts. We then describe our experiences of using Deep Viewpoints with communities traditionally underserved by the museum sector to bring new perspectives to the museum collection. Crucially, the communities were not only involved in interpreting artworks with the guidance of the scripts but also creating new scripts, mediating how others observe and think about art. Analysis of the authored scripts revealed a range of ways in which they were used to share interpretations of the artworks and mediate what questions others should ask themselves when viewing the artworks. Finally, we reflect on the potential role a scripted approach to Citizen Curation could play in promoting cultural engagement
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Uncomfortable Revelations: can citizen curation widen access to museums?
Can citizen curation facilitate diverse participation in museums? Through their contribution to the European Union Horizon 2020 SPICE Project, IMMA and The Open University are developing a case study which uses digital technologies to support communities to select and interpret works of art and share their perspectives. Reflecting on workshops with underrepresented communities, this article outlines the concept of citizen curation and argues for the potential of Slow Looking as a means of promoting active participation
Survey Mode Effects on Valuation of Environmental Goods
This article evaluates the effect of the choice of survey recruitment mode on the value of water quality in lakes, rivers, and streams. Four different modes are compared: bringing respondents to one central location after phone recruitment, mall intercepts in two states, national phone-mail survey, and an Internet survey with a national, probability-based panel. The modes differ in terms of the representativeness of the samples, non-response rates, sample selection effects, and consistency of responses. The article also shows that the estimated value of water quality can differ substantially depending on the survey mode. The national Internet panel has the most desirable properties with respect to performance on the four important survey dimensions of interest
PFMDR1 AND IN VIVO RESISTANCE TO ARTESUNATE-MEFLOQUINE IN FALCIPARUM MALARIA ON THE CAMBODIAN–THAI BORDER
Artemisinin combination therapies (ACTs) have recently been adopted as first-line therapy for Plasmodium
falciparum infections in most malaria-endemic countries. In this study, we estimated the association between
artesunate-mefloquine therapy failure and genetic changes in the putative transporter, pfmdr1. Blood samples were
acquired from 80 patients enrolled in an 2004 in vivo efficacy study in Pailin, Cambodia, and genotyped for pfmdr1 copy
number and haplotype. Having parasites with three or more copies of pfmdr1 before treatment was strongly associated
with recrudescence (hazard ratio [HR] = 8.30; 95% CI: 2.60–26.43). This relationship was maintained when controlling
for initial parasite density and hematocrit (HR = 7.91; 95% CI: 2.38–26.29). Artesunate-mefloquine treatment selected
for increased pfmdr1 copy number, because isolates from recurrent episodes had higher copy numbers than the paired
enrollment samples (Wilcoxon rank test, P = 0.040). pfmdr1 copy number should be evaluated further as a surveillance
tool for artesunate-mefloquine resistance in Cambodia
Molecular Surveillance for Multidrug-Resistant Plasmodium falciparum, Cambodia
We conducted surveillance for multidrug-resistant Plasmodium falciparum in Cambodia during 2004–2006 by assessing molecular changes in pfmdr1. The high prevalence of isolates with multiple pfmdr1 copies found in western Cambodia near the Thai border, where artesunate–mefloquine therapy failures occur, contrasts with isolates from eastern Cambodia, where this combination therapy remains highly effective
Analytical and Biological Characterization of Supercoiled Plasmids Purified by Various Chromatographic Techniques
This is the publisher's version, also available electronically from http://online.liebertpub.com/doi/abs/10.1089/dna.2005.24.819Supercoiled plasmids are an important component of gene-based delivery vehicles. A number of production methods for clinical applications have been developed, each resulting in very high-quality product with low levels of residual contaminants. There is, however, no consensus on the optimal methods to characterize plasmid quality, and further, to determine if these methods are predictive of either product stability or biological activity. We have produced two plasmids using four production purification methodologies based on PolyFlo® and hydrophobic interaction chromatography (HIC), either alone or in tandem processes. In each case, the product was analyzed using standard molecular biological methods. We also performed a number of biophysical analyses such as dynamic light scattering (DLS), circular dichroism (CD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). Minimal differences were detected among the preparations based on the more standard molecular biological methods. Some small differences were detected, however, using biophysical techniques, particularly FTIR and DSC, which may reflect small variations in plasmid tertiary structure and thermal stability. Stability after heat exposure at 60°C, exposure to fetal bovine serum and long-term storage at 4°C varied between plasmids. One plasmid showed no difference in stability depending on the production process, but the other showed significant differences. Evaluation in vivo in models for gene immunization and gene therapy showed significant differences in the response depending on the method of purification. Preparations using a tandem process of PolyFlo used in two separation modes provided higher biological activity compared to a tandem HIC/PolyFlo process or either resin used alone in a single column process. These data indicate that the process by which supercoiled plasmids are made can influence plasmid stability and biological activity and emphasize the need for more rigorous methods to evaluate supercoiled plasmids as gene-delivery vehicles
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