3,233 research outputs found
Neutron star cooling after deep crustal heating in the X-ray transient KS 1731-260
We simulate the cooling of the neutron star in the X-ray transient KS
1731-260 after the source returned to quiescence in 2001 from a long (>~ 12.5
yr) outburst state. We show that the cooling can be explained assuming that the
crust underwent deep heating during the outburst stage. In our best theoretical
scenario the neutron star has no enhanced neutrino emission in the core, and
its crust is thin, superfluid, and has the normal thermal conductivity. The
thermal afterburst crust-core relaxation in the star may be not over.Comment: 5 pages, 2 figures, accepted by MNRAS. In v.2, two references added
and typos correcte
Exploring Outliers in Crowdsourced Ranking for QoE
Outlier detection is a crucial part of robust evaluation for crowdsourceable
assessment of Quality of Experience (QoE) and has attracted much attention in
recent years. In this paper, we propose some simple and fast algorithms for
outlier detection and robust QoE evaluation based on the nonconvex optimization
principle. Several iterative procedures are designed with or without knowing
the number of outliers in samples. Theoretical analysis is given to show that
such procedures can reach statistically good estimates under mild conditions.
Finally, experimental results with simulated and real-world crowdsourcing
datasets show that the proposed algorithms could produce similar performance to
Huber-LASSO approach in robust ranking, yet with nearly 8 or 90 times speed-up,
without or with a prior knowledge on the sparsity size of outliers,
respectively. Therefore the proposed methodology provides us a set of helpful
tools for robust QoE evaluation with crowdsourcing data.Comment: accepted by ACM Multimedia 2017 (Oral presentation). arXiv admin
note: text overlap with arXiv:1407.763
Small and beautiful? The programme of activities and the least developed countries
Most carbon abatement projects under the Kyoto Protocol's Clean Development Mechanism (CDM) have been implemented in rapidly industrializing countries, notably China and India. To support small carbon abatement projects and to promote decarbonization in the least developed countries, the Programme of Activities (PoA) modality was introduced. Are the determinants of project implementation different under the PoA from those of conventional CDM projects? To answer this question, we conduct a statistical analysis of the global distribution of CDM projects and PoAs during the years 2007â2012. In regard to country size, large countries clearly dominate both the CDM and PoA, suggesting that the PoA may do only little to facilitate project implementation in small countries. However, the number of PoAs has a strong negative association with a country's corruption level, while the importance of corruption for the CDM is much smaller. Moreover, per capita income has no effect on PoA implementation, while high wealth levels have a weak positive effect on CDM projects. Thus, the PoA modality seems to promote sustainable development in poor countries that have exceeded a certain threshold of good governance. In this regard, PoAs are directing carbon credits to new areas, as many had initially hoped
Electron capture reactions in neutron star crusts: deep heating and observational constraints
Tuning the Clock: Uranium and Thorium Chronometers Applied to CS 31082-001
We obtain age estimates for the progenitor(s) of the extremely metal-poor
([Fe/H = -2.9) halo star CS 31082-001, based on the recently reported first
observation of a Uranium abundance in this (or any other) star. Age estimates
are derived by application of the classical r-process model with updated
nuclear physics inputs. The [U/Th] ratio yields an age of 13+-4 Gyr or 8+-4
Gyr, based on the use of the ETFSI-Q or the new HFBCS-1 nuclear mass models,
respectively. Implications for Thorium chronometers are discussed.Comment: 5 pages incl. 1 figure, a shorter 3 page version will be published in
the proceedings of the "Astrophysical Ages and Timescales" conference held in
Hilo, Hawaii, Feb 5-9, 200
Oxford Nanopore sequencing, hybrid error correction, and de novo assembly of a eukaryotic genome
Monitoring the progress of DNA molecules through a membrane pore has been postulated as a method for sequencing DNA for several decades. Recently, a nanopore-based sequencing instrument, the Oxford Nanopore MinION, has become available, and we used this for sequencing the Saccharomyces cerevisiae genome. To make use of these data, we developed a novel open-source hybrid error correction algorithm Nanocorr specifically for Oxford Nanopore reads, because existing packages were incapable of assembling the long read lengths (5-50 kbp) at such high error rates (between approximately 5% and 40% error). With this new method, we were able to perform a hybrid error correction of the nanopore reads using complementary MiSeq data and produce a de novo assembly that is highly contiguous and accurate: The contig N50 length is more than ten times greater than an Illumina-only assembly (678 kb versus 59.9 kbp) and has >99.88% consensus identity when compared to the reference. Furthermore, the assembly with the long nanopore reads presents a much more complete representation of the features of the genome and correctly assembles gene cassettes, rRNAs, transposable elements, and other genomic features that were almost entirely absent in the Illumina-only assembly
Decaying Dark Energy in Higher-Dimensional Gravity
We use data from observational cosmology to put constraints on
higher-dimensional extensions of general relativity in which the effective
four-dimensional dark-energy density (or cosmological "constant") decays with
time. In particular we study the implications of this decaying dark energy for
the age of the universe, large-scale structure formation, big-bang
nucleosynthesis and the magnitude-redshift relation for Type Ia supernovae. Two
of these tests (age and the magnitude-redshift relation) place modest lower
limits on the free parameter of the theory, a cosmological length scale L akin
to the de Sitter radius. These limits will improve if experimental
uncertainties on supernova magnitudes can be reduced around z=1.Comment: 11 pages, 5 figures, submitted to A&
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Ultralow-threshold, continuous-wave upconverting lasing from subwavelength plasmons.
Miniaturized lasers are an emerging platform for generating coherent light for quantum photonics, in vivo cellular imaging, solid-state lighting and fast three-dimensional sensing in smartphones1-3. Continuous-wave lasing at room temperature is critical for integration with opto-electronic devices and optimal modulation of optical interactions4,5. Plasmonic nanocavities integrated with gain can generate coherent light at subwavelength scales6-9, beyond the diffraction limit that constrains mode volumes in dielectric cavities such as semiconducting nanowires10,11. However, insufficient gain with respect to losses and thermal instabilities in nanocavities has limited all nanoscale lasers to pulsed pump sources and/or low-temperature operation6-9,12-15. Here, we show continuous-wave upconverting lasing at room temperature with record-low thresholds and high photostability from subwavelength plasmons. We achieve selective, single-mode lasing from Yb3+/Er3+-co-doped upconverting nanoparticles conformally coated on Ag nanopillar arrays that support a single, sharp lattice plasmon cavity mode and greater than wavelength λ/20 field confinement in the vertical dimension. The intense electromagnetic near-fields localized in the vicinity of the nanopillars result in a threshold of 70âWâcm-2, orders of magnitude lower than other small lasers. Our plasmon-nanoarray upconverting lasers provide directional, ultra-stable output at visible frequencies under near-infrared pumping, even after six hours of constant operation, which offers prospects in previously unrealizable applications of coherent nanoscale light
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