350 research outputs found
Rich methane laminar flames doped with light unsaturated hydrocarbons. Part II: 1,3butadiene
In line with the study presented in the part I of this paper, the structure
of a laminar rich premixed methane flame doped with 1,3-butadiene has been
investigated. The flame contains 20.7% (molar) of methane, 31.4% of oxygen and
3.3% of 1,3-butadiene, corresponding to an equivalence ratio of 1.8, and a
ratio C4H6 / CH4 of 16 %. The flame has been stabilized on a burner at a
pressure of 6.7 kPa using argon as dilutant, with a gas velocity at the burner
of 36 cm/s at 333 K. The temperature ranged from 600 K close to the burner up
to 2150 K. Quantified species included usual methane C0-C2 combustion products
and 1,3-butadiene, but also propyne, allene, propene, propane, 1,2-butadiene,
butynes, vinylacetylene, diacetylene, 1,3-pentadiene, 2-methyl-1,3-butadiene
(isoprene), 1-pentene, 3-methyl-1-butene, benzene and toluene. In order to
model these new results, some improvements have been made to a mechanism
previously developed in our laboratory for the reactions of C3-C4 unsaturated
hydrocarbons. The main reaction pathways of consumption of 1,3-butadiene and of
formation of C6 aromatic species have been derived from flow rate analyses. In
this case, the C4 route to benzene formation plays an important role in
comparison to the C3 pathway
A Comparative Study of the Formation of Aromatics in Rich Methane Flames Doped by Unsaturated Compounds
For a better modeling of the importance of the different channels leading to
the first aromatic ring, we have compared the structures of laminar rich
premixed methane flames doped with several unsaturated hydrocarbons: allene and
propyne, because they are precursors of propargyl radicals which are well known
as having an important role in forming benzene, 1,3-butadiene to put in
evidence a possible production of benzene due to reactions of C4 compounds,
and, finally, cyclopentene which is a source of cyclopentadienylmethylene
radicals which in turn are expected to easily isomerizes to give benzene. These
flames have been stabilized on a burner at a pressure of 6.7 kPa (50 Torr)
using argon as dilutant, for equivalence ratios (?) from 1.55 to 1.79. A unique
mechanism, including the formation and decomposition of benzene and toluene,
has been used to model the oxidation of allene, propyne, 1,3 butadiene and
cyclopentene. The main reaction pathways of aromatics formation have been
derived from reaction rate and sensitivity analyses and have been compared for
the three types of additives. These combined analyses and comparisons can only
been performed when a unique mechanism is available for all the studied
additives
Nonlinear coupled Alfv\'{e}n and gravitational waves
In this paper we consider nonlinear interaction between gravitational and
electromagnetic waves in a strongly magnetized plasma. More specifically, we
investigate the propagation of gravitational waves with the direction of
propagation perpendicular to a background magnetic field, and the coupling to
compressional Alfv\'{e}n waves. The gravitational waves are considered in the
high frequency limit and the plasma is modelled by a multifluid description. We
make a self-consistent, weakly nonlinear analysis of the Einstein-Maxwell
system and derive a wave equation for the coupled gravitational and
electromagnetic wave modes. A WKB-approximation is then applied and as a result
we obtain the nonlinear Schr\"{o}dinger equation for the slowly varying wave
amplitudes. The analysis is extended to 3D wave pulses, and we discuss the
applications to radiation generated from pulsar binary mergers. It turns out
that the electromagnetic radiation from a binary merger should experience a
focusing effect, that in principle could be detected.Comment: 20 pages, revtex4, accepted in PR
Emergence of a novel GII.17 norovirus – end of the GII.4 era?
In the winter of 2014/15 a novel GII.P17-GII.17 norovirus strain (GII.17 Kawasaki 2014) emerged, as a major cause of gastroenteritis outbreaks in China and Japan. Since their emergence these novel GII.P17-GII.17 viruses have replaced the previously dominant GII.4 genotype Sydney 2012 variant in some areas in Asia but were only detected in a limited number of cases on other continents. This perspective provides an overview of the available information on GII.17 viruses in order to gain insight in the viral and host characteristics of this norovirus genotype. We further discuss the emergence of this novel GII.P17-GII.17 norovirus in context of current knowledge on the epidemiology of noroviruses. It remains to be seen if the currently dominant norovirus strain GII.4 Sydney 2012 will be replaced in other parts of the world. Nevertheless, the public health community and surveillance systems need to be prepared in case of a potential increase of norovirus activity in the next seasons caused by this novel GII.P17-GII.17 norovirus
In Silico Veritas: The Pitfalls and Challenges of Predicting
Recently the first community-wide assessments of the prediction of the structures of complexes between proteins and small molecule ligands have been reported in the so-called GPCR Dock 2008 and 2010 assessments. In the current review we discuss the different steps along the protein-ligand modeling workflow by critically analyzing the modeling strategies we used to predict the structures of protein-ligand complexes we submitted to the recent GPCR Dock 2010 challenge. These representative test cases, focusing on the pharmaceutically relevant G Protein-Coupled Receptors, are used to demonstrate the strengths and challenges of the different modeling methods. Our analysis indicates that the proper performance of the sequence alignment, introduction of structural adjustments guided by experimental data, and the usage of experimental data to identify protein-ligand interactions are critical steps in the protein-ligand modeling protocol. © 2011 by the authors; licensee MDPI, Basel, Switzerland
Emergence of a novel GII.17 norovirus – end of the GII.4 era?
In the winter of 2014/15 a novel GII.P17-GII.17 norovirus
strain (GII.17 Kawasaki 2014) emerged, as a major
cause of gastroenteritis outbreaks in China and Japan.
Since their emergence these novel GII.P17-GII.17
viruses have replaced the previously dominant GII.4
genotype Sydney 2012 variant in some areas in Asia
but were only detected in a limited number of cases on
other continents. This perspective provides an overview
of the available information on GII.17 viruses in
order to gain insight in the viral and host characteristics
of this norovirus genotype. We further discuss
the emergence of this novel GII.P17-GII.17 norovirus
in context of current knowledge on the epidemiology
of noroviruses. It remains to be seen if the currently
dominant norovirus strain GII.4 Sydney 2012 will be
replaced in other parts of the world. Nevertheless,
the public health community and surveillance systems
need to be prepared in case of a potential increase of
norovirus activity in the next seasons caused by this
novel GII.P17-GII.17 norovirus.The EU H2020 grant COMPARE under grant
agreement number 643476 and the Virgo Consortium, funded
by Dutch government project number FES0908 and the
Hungarian Scientific Research Fund (OTKA/NKFIH K111615).http://www.eurosurveillance.orgam201
The differential diagnosis of chronic daily headaches: an algorithm-based approach
Chronic daily headaches (CDHs) refers to primary headaches that happen on at least 15 days per month, for 4 or more hours per day, for at least three consecutive months. The differential diagnosis of CDHs is challenging and should proceed in an orderly fashion. The approach begins with a search for “red flags” that suggest the possibility of a secondary headache. If secondary headaches that mimic CDHs are excluded, either on clinical grounds or through investigation, the next step is to classify the headaches based on the duration of attacks. If the attacks last less than 4 hours per day, a trigeminal autonomic cephalalgia (TAC) is likely. TACs include episodic and chronic cluster headache, episodic and chronic paroxysmal hemicrania, SUNCT, and hypnic headache. If the duration is ≥4 h, a CDH is likely and the differential diagnosis encompasses chronic migraine, chronic tension-type headache, new daily persistent headache and hemicrania continua. The clinical approach to diagnosing CDH is the scope of this review
Phase 1 study of the MDM2 inhibitor AMG 232 in patients with advanced P53 wild-type solid tumors or multiple myeloma
_Background_ This open-label, first-in-human, phase 1 study evaluated AMG 232, an oral selective MDM2 inhibitor in patients with TP53 wild-type (P53WT), advanced solid tumors or multiple myeloma (MM).
_Methods_ In the dose escalation (n = 39), patients with P53WT refractory solid tumors enrolled to receive once-dailyAMG 232 (15, 30, 60, 120, 240, 480, and 960 mg) for seven days every 3 weeks (Q3W). In the dose expansion (n = 68), patients with MDM2-amplified (well-differentiated and dedifferentiated liposarcomas [WDLPS and DDLPS], glioblastoma multiforme [GBM], or other solid tumors [OST]), MDM2-overexpressing ER+ breast cancer (BC), or MM received AMG 232 at the maximum tolerated dose (MTD). Safety, pharmacokinetics, pharmacodynamics, and efficacy were assessed.
_Results_ AMG 232 had acceptable safety up to up to 240 mg
Learning from multimedia and hypermedia
Computer-based multimedia and hypermedia resources (e.g., the world wide web) have become one of the primary sources of academic information for a majority of pupils and students. In line with this expansion in the field of education, the scientific study of learning from multimedia and hypermedia has become a very active field of research. In this chapter we provide a short overview with regard to research on learning with multimedia and hypermedia. In two review sections, we describe the educational benefits of multiple representations and of learner control, as these are the two defining characteristics of hypermedia. In a third review section we describe recent scientific trends in the field of multimedia/hypermedia learning. In all three review sections we will point to relevant European work on multimedia/hypermedia carried out within the last 5 years, and often carried out within the Kaleidoscope Network of Excellence. According to the interdisciplinary nature of the field this work might come not only from psychology, but also from technology or pedagogy. Comparing the different research activities on multimedia and hypermedia that have dominated the international scientific discourse in the last decade reveals some important differences. Most important, a gap seems to exist between researchers mainly interested in a “serious” educational use of multimedia/ hypermedia and researchers mainly interested in “serious” experimental research on learning with multimedia/hypermedia. Recent discussions about the pros and cons of “design-based research” or “use-inspired basic research” can be seen as a direct consequence of an increasing awareness of the tensions within these two different cultures of research on education
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