We demonstrate triggered single photon emission at room temperature from a site-controlled III-nitride quantum dot embedded in a nanowire. Moreover, we reveal a remarkable temperature insensitivity ...of the single photon statistics, and a g (2)0 value at 300 K of just 0.13. The combination of using high-quality, small, site-controlled quantum dots with a wide-bandgap material system is crucial for providing both sufficient exciton confinement and an emission spectrum with minimal contamination in order to enable room temperature operation. Arrays of such single photon emitters will be useful for room-temperature quantum information processing applications such as on-chip quantum communication.
Highlights • A novel mecA homologue, mecC , confers methicillin resistance to methicillin-resistant Staphylococcus aureus (MRSA). • mecC MRSA produce negative results with common diagnostic tools. • ...Reported from throughout Western Europe. Recent increase in Denmark. • Found in a range of host species and may pose a zoonotic risk to humans.
Wide bandgap III-nitride quantum dots (QDs) are promising materials for the realization of solid-state single-photon sources, especially operating at room temperature. However, so far a large degree ...of inhomogeneous broadening induced by spectral diffusion has compromised their use. Here, we demonstrate the ultraclean emission from single GaN QDs formed at macrostep edges in a GaN/AlGaN quantum well. As a likely consequence of the high growth temperature and hence a reduced defect density, spectral diffusion is heavily suppressed to levels at least 1 order of magnitude lower than conventional GaN QDs. A record narrow line width of as small as 87 μeV is obtained, while the low inhomogeneous broadening enables us to assess an upper limit of homogeneous broadening in the QDs (27 μeV). Furthermore, the uncontaminated emission facilitates the generation of ultraviolet single-photons with unprecedented purity (g (2)(0) = 0.02). The realization of high-quality GaN QDs will enable exploration of optoelectronic properties of III-nitrides, opening up the possibility of realizing single-photon quantum information systems operating at room temperature.
The connections between the error function used in multilinear regression and the expected, or assumed, properties of the data are investigated. It is shown that two of the most basic properties ...often required in data analysis, scale and rotational invariance, are incompatible. With this, it is established that multilinear regression using an error function derived from a geometric mean is both scale and reflectively invariant. The resulting error function is also shown to have the property that its minimizer, under certain conditions, is well approximated using the centroid of the error simplex. It is then applied to several multidimensional real world data sets, and compared to other regression methods.
Society is facing significant environmental challenges. The effects of climate change, biodiversity loss and environmental degradation are being increasingly felt worldwide. In recent years, ...researchers have attempted to adapt neoclassical and endogenous growth theory to account for constraints imposed by scarce natural resources. In this article, we review where, and how, researchers tend to incorporate natural resources and natural capital into growth theory. We then outline areas and questions that remain unanswered, including how novel impact investing and the eroding trade‐off between GDP and the environment affect growth theory.
Analysis of the coupling between the phases and amplitudes of oscillations within the same continuously sampled signal has provided interesting insights into the physiology of memory and other brain ...process, and, more recently, the pathophysiology of parkinsonism and other movement disorders. Technical aspects of the analysis have a significant impact on the results. We present an empirical exploration of a variety of analysis design choices that need to be considered when measuring phase-amplitude coupling (PAC). We studied three alternative filtering approaches to the commonly used Kullback-Leibler distance-based method of PAC analysis, including one method that uses wavelets, one that uses constant filter settings, and one in which filtering of the data is optimized for individual frequency bands. Additionally, we introduce a time-dependent PAC analysis technique that takes advantage of the inherent temporality of wavelets. We examined how the duration of the sampled data, the stability of oscillations, or the presence of artifacts affect the value of the "modulation index", a commonly used parameter describing the degree of PAC. We also studied the computational costs associated with calculating modulation indices by the three techniques. We found that wavelet-based PAC performs better with similar or less computational cost than the two other methods while also allowing to examine temporal changes of PAC. We also show that the reliability of PAC measurements strongly depends on the duration and stability of PAC, and the presence (or absence) of artifacts. The best parameters to be used for PAC analyses of long samples of data may differ, depending on data characteristics and analysis objectives. Prior to settling on a specific PAC analysis approach for a given set of data, it may be useful to conduct an initial analysis of the time-dependence of PAC using our time-resolved PAC analysis.
Vancomycin-resistant
(VREfm) is a major cause of nosocomial infection and is categorized as high priority by the World Health Organization global priority list of antibiotic-resistant bacteria. In ...the past, livestock have been proposed as a putative reservoir for drug-resistant
strains that infect humans, and isolates of the same lineage have been found in both reservoirs. We undertook cross-sectional surveys to isolate
(including VREfm) from livestock farms, retail meat, and wastewater treatment plants in the United Kingdom. More than 600 isolates from these sources were sequenced, and their relatedness and antibiotic resistance genes were compared with genomes of almost 800
isolates from patients with bloodstream infection in the United Kingdom and Ireland.
was isolated from 28/29 farms; none of these isolates were VREfm, suggesting a decrease in VREfm prevalence since the last UK livestock survey in 2003. However, VREfm was isolated from 1% to 2% of retail meat products and was ubiquitous in wastewater treatment plants. Phylogenetic comparison demonstrated that the majority of human and livestock-related isolates were genetically distinct, although pig isolates from three farms were more genetically related to human isolates from 2001 to 2004 (minimum of 50 single-nucleotide polymorphisms SNPs). Analysis of accessory (variable) genes added further evidence for distinct niche adaptation. An analysis of acquired antibiotic resistance genes and their variants revealed limited sharing between humans and livestock. Our findings indicate that the majority of
strains infecting patients are largely distinct from those from livestock in this setting, with limited sharing of strains and resistance genes.
The rise in rates of human infection caused by vancomycin-resistant
(VREfm) strains between 1988 to the 2000s in Europe was suggested to be associated with acquisition from livestock. As a result, the European Union banned the use of the glycopeptide drug avoparcin as a growth promoter in livestock feed. While some studies reported a decrease in VREfm in livestock, others reported no reduction. Here, we report the first livestock VREfm prevalence survey in the UK since 2003 and the first large-scale study using whole-genome sequencing to investigate the relationship between
strains in livestock and humans. We found a low prevalence of VREfm in retail meat and limited evidence for recent sharing of strains between livestock and humans with bloodstream infection. There was evidence for limited sharing of genes encoding antibiotic resistance between these reservoirs, a finding which requires further research.
Staphylococcus aureus is an important human bacterial pathogen that has a cosmopolitan host range, including livestock, companion and wild animal species. Genomic and epidemiological studies show ...that S. aureus has jumped between host species many times over its evolutionary history. These jumps have involved the dynamic gain and loss of host-specific adaptive genes, usually located on mobile genetic elements. The same functional elements are often consistently gained in jumps into a particular species. Further sampling of diverse animal species is likely to uncover an even broader host range and greater genetic diversity of S. aureus than is already known, and understanding S. aureus host specificity in these hosts will mitigate the risks of emergent human and livestock strains.
Based on its broad host range, S. aureus can be described as a generalist pathogen.On short evolutionary timescales, however, strains are host specialists.S. aureus is capable of rapid adaptation to a wide range of hosts, mainly through the acquisition of mobile genetic elements (MGEs).Host shifts are a dynamic and a regular feature of S. aureus evolution.A large diversity of animal strains of S. aureus remain uncharacterized.Inferring the host ecology of strains of S. aureus from their genomes will aid surveillance and diagnostics
We carry out a (partial) replication exercise of Chang and Lee (2015) unit root and cointegration analyses of crude oil spot and futures prices. In doing so, we offer an updated and expanded analysis ...based on a much wider set of oil futures series than that considered by Chang and Lee, and we consider the impact of different temporal aggregation methods. Although we are not able to exactly replicate their findings, we nonetheless reach qualitatively similar findings to theirs when using their dataset in terms of the long-run properties and interactions of the spot and futures prices data. Likewise, qualitatively comparable results are obtained when using our expanded dataset. However, a number of important qualitative differences from Chang and Lee arise in terms of the analysis of causality between spot and futures contract prices. As part of our replication exercise we also investigate some aspects that were not originally considered by Chang and Lee. In doing this, we find that both the variability of futures prices as well as the speed of adjustment of futures/spot price differentials increase as the maturity of the contracts increase.
•We carry out a (partial) replication exercise of Chang and Lee (2015).•We analyse a much wider set of oil futures series.•Qualitative differences arise in causality between spot and futures contract prices.•The speed of adjustment of futures/spot price differentials increases with maturity.•We find evidence against the Samuelson effect.
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