994 research outputs found
X-Ray Grating Observations of Recurrent Nova T Pyxidis During The 2011 Outburst
The recurrent nova T Pyx was observed with the X-ray gratings of Chandra and
XMM-Newton, 210 and 235 days, respectively, after the discovery of the 2011
April 14 outburst. The X-ray spectra show prominent emission lines of C, N, and
O, with broadening corresponding to a full width at half maximum of ~2000-3000
km/s, and line ratios consistent with high-density plasma in collisional
ionization equilibrium. On day 210 we also measured soft X-ray continuum
emission that appears to be consistent with a white dwarf (WD) atmosphere at a
temperature ~420,000 K, partially obscured by anisotropic, optically thick
ejecta. The X-ray continuum emission is modulated with the photometric and
spectroscopic period observed in quiescence. The continuum at day 235 indicated
a WD atmosphere at a consistent effective temperature of 25 days earlier, but
with a lower flux. The effective temperature indicates a mass of ~1 solar mass.
The conclusion of partial WD obscuration is supported by the complex geometry
of non-spherically-symmetric ejecta confirmed in recent optical spectra
obtained with the Southern African Large Telescope (SALT) in November and
December of 2012. These spectra exhibited prominent [O III] nebular lines with
velocity structures typical of bipolar ejecta.Comment: Accepted to ApJ 2013 October 23, 14 pages, 9 figures, 3 table
Bistability in an injection locked two color laser with dual injection
A two color Fabry-Perot laser subjected to optical injection in both modes is examined experimentally and theoretically. The theoretical analysis predicts a bistability between locked states due to a swallow-tail bifurcation, which is unique to the dual injection system. This bistability is confirmed experimentally and used as the basis for an all optical memory element with switching times below 500 ps. (C) 2011 American Institute of Physics. (doi: 10.1063/1.3605584
Socio-psychological factors, beyond knowledge, predict people's engagement in pollinator conservation
1. Nature conservation often depends on the behaviour of individuals, which can bedriven by socio-psychological factors such as a person's attitude, knowledge andidentity. Despite extensive ecological research about pollinator declines, there hasbeen almost no social research assessing the drivers of people's engagement inpollinator conservation.2. To address this gap, we used a large-scale, online questionnaire in the UnitedKingdom, broadly framed around the Theory of Planned Behaviour. We received atotal of 1,275 responses from a wide range of ages, incomes and education levels,despite a selection bias towards people with a pre-existing interest in pollinators.3. A range of socio-psychological factors predicted people's pollinator conservation actions and explained 45% of the variation. Respondentsâ diversity of natureinteractions and perceived behavioural control (feeling able to help pollinators)were consistently important predictors of people's pollinator conservation actions, whilst the importance of other socio-psychological factors depended onthe particular action.4. Notably, knowledge was far less important overall than people's perceptions andother socio-psychological factors, highlighting a knowledge-action gap. Furtherunexplained variation in people's behaviour could partly be due by structural andcontextual factors, particularly regarding social norms around tidiness.5. From a practical perspective, our findings reveal three main insights. First, several simple, low-cost pollinator conservation actions (reduced mowing, leavingareas unmown and creating patches of bare ground for ground-nesting bees)are currently under-utilised so should be priorities for pollinator conservationprogrammes.6. Second, strategies are needed to overcome reported practical barriers, for example by providing free resources (e.g. seeds of pollen- and nectar-rich plants) andcommunicating simple beneficial actions that can be carried out with limited time,space and money
Freak Waves in Random Oceanic Sea States
Freak waves are very large, rare events in a random ocean wave train. Here we
study the numerical generation of freak waves in a random sea state
characterized by the JONSWAP power spectrum. We assume, to cubic order in
nonlinearity, that the wave dynamics are governed by the nonlinear Schroedinger
(NLS) equation. We identify two parameters in the power spectrum that control
the nonlinear dynamics: the Phillips parameter and the enhancement
coefficient . We discuss how freak waves in a random sea state are more
likely to occur for large values of and . Our results are
supported by extensive numerical simulations of the NLS equation with random
initial conditions. Comparison with linear simulations are also reported.Comment: 7 pages, 6 figures, to be published in Phys. Rev. Let
The implementation of omics technologies in cancer microbiome research
Whilst the interplay between host genetics and the environment plays a pivotal role in the aetiopathogenesis of cancer, there are other key contributors of importance as well. One such factor of central and growing interest is the contribution of the microbiota to cancer. Even though the field is only a few years old, investigation of the âcancer microbiomeâ has already led to major advances in knowledge of the basic biology of cancer risk and progression, opened novel avenues for biomarkers and diagnostics, and given a better understanding of mechanisms underlying response to therapy. Recent developments in microbial DNA sequencing techniques (and the bioinformatics required for analysis of these datasets) have allowed much more in-depth profiling of the structure of microbial communities than was previously possible. However, for more complete assessment of the functional implications of microbial changes, there is a growing recognition of the importance of the integration of microbial profiling with other omics modalities, with metabonomics (metabolite profiling) and proteomics (protein profiling) both gaining particular recent attention. In this review, we give an overview of some of the key scientific techniques being used to unravel the role of the cancer microbiome. We have aimed to highlight practical aspects related to sample collection and preparation, choice of the modality of analysis, and examples of where different omics technologies have been complementary to each other to highlight the significance of the cancer microbiome
Ecosystem service provision by road verges
1. Roads form a vast, rapidly growing global network that has diverse, detrimental ecological impacts. However, the habitats that border roads (âroad vergesâ) form a parallel network that might help mitigate these impacts and provide additional benefits (ecosystem services; ES).
2. We evaluate the capacity of road verges to provide ES by reviewing existing research and considering their relevant characteristics: area, connectivity, shape, and contextual ES supply and demand. We consider the present situation, and how this is likely to change based on future projections for growth in road extent, traffic densities and urban populations.
3. Road verges not only provide a wide range of ES, including biodiversity provision, regulating services (e.g. air and water filtration) and cultural services (e.g. health and aesthetic benefits by providing access to nature) but also displace other habitats and provide ecosystem disservices (e.g. plant allergens and damage to infrastructure). Globally, road verges may currently cover 270,000 km2 and store 0.015 Gt C/year, which will further increase with 70% projected growth in the global road network.
4. Road verges are well placed to mitigate traffic pollution and address demand for ES in surrounding ESâimpoverished landscapes, thereby improving human health and wellâbeing in urban areas, and improving agricultural production and sustainability in farmland. Demand for ES provided by road verges will likely increase due to projected growth in traffic densities and urban populations, though traffic pollution will be reduced by technological advances (e.g. electric vehicles). Road verges form a highly connected network, which may enhance ES provision but facilitate the dispersal of invasive species and increase vehicleâwildlife collisions.
5. Synthesis and applications. Road verges offer a significant opportunity to mitigate the negative ecological effects of roads and to address demand for ecosystem services (ES) in urban and agricultural landscapes. Their capacity to provide ES might be enhanced considerably if they were strategically designed and managed for environmental outcomes, namely by optimizing the selection, position and management of plant species and habitats. Specific opportunities include reducing mowing frequencies and planting trees in large verges. Road verge management for ES must consider safety guidelines, financial costs and ecosystem disservices, but is likely to provide longâterm financial returns if environmental benefits are considered
Approximate rogue wave solutions of the forced and damped Nonlinear Schr\"odinger equation for water waves
We consider the effect of the wind and the dissipation on the nonlinear
stages of the modulational instability. By applying a suitable transformation,
we map the forced/damped Nonlinear Schr\"odinger (NLS) equation into the
standard NLS with constant coefficients. The transformation is valid as long as
|{\Gamma}t| \ll 1, with {\Gamma} the growth/damping rate of the waves due to
the wind/dissipation. Approximate rogue wave solutions of the equation are
presented and discussed. The results shed some lights on the effects of wind
and dissipation on the formation of rogue waves.Comment: 10 pages, 3 figure
Fidelity, entanglement, and information complementarity relation
We investigate the dynamics of information in isolated multi-qubit systems.
It is shown that information is in not only local form but also nonlocal form.
We apply a measure of local information based on fidelity, and demonstrate that
nonlocal information can be directly related to some appropriate well defined
entanglement measures. Under general unitary transformations, local and
nonlocal information will exhibit unambiguous complementary behavior with the
total information conserved.Comment: 5 pages, 3 figure
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