824 research outputs found
A novel scene-recording spectroradiometer
In this paper we describe an innovative approach to providing both a
synthesised dual-beam capability and a permanent photographic record of the
precise area sensed by a spectroradiometer. These advances have been achieved
without modifying the spectroradiometer and may be used with a wide range of
commercially-available spectroradiometers
No difference in variability of unique hue selections and binary hue selections
If unique hues have special status in phenomenological experience as perceptually pure, it seems reasonable to assume that they are represented more precisely by the visual system than are other colors. Following the method of Malkoc et al. (J. Opt. Soc. Am. A22, 2154 [2005]), we gathered unique and binary hue selections from 50 subjects. For these subjects we repeated the measurements in two separate sessions, allowing us to measure test-retest reliabilities (0.52≤ρ≤0.78; p≪0.01). We quantified the within-individual variability for selections of each hue. Adjusting for the differences in variability intrinsic to different regions of chromaticity space, we compared the within-individual variability for unique hues to that for binary hues. Surprisingly, we found that selections of unique hues did not show consistently lower variability than selections of binary hues. We repeated hue measurements in a single session for an independent sample of 58 subjects, using a different relative scaling of the cardinal axes of MacLeod-Boynton chromaticity space. Again, we found no consistent difference in adjusted within-individual variability for selections of unique and binary hues. Our finding does not depend on the particular scaling chosen for the Y axis of MacLeod-Boynton chromaticity space
Multi-locus sequence typing of Escherichia coli isolates with acquired ampC genes and ampC promoter mutations
© 2016 Elsevier Inc. Multi-locus sequence typing was used to reveal a high degree of diversity amongst the E. coli isolates with AmpC plasmid genes, and a high prevalence of the −32 mutation present
Chromosomal ampC mutations in cefpodoxime-resistant ESBL-negative uropathogenic escherichia coli
AmpC beta-lactamase is an enzyme commonly produced by Escherichia coli that causes resistance to cephalosporins and penicillins. Enzyme production is controlled by the strength of the promoter encoded by the chromosomal ampC gene, with the level of production affected by the presence of certain mutations in this region. This study sets out to determine the prevalence of ampC promoter mutations present in a group of uropathogenic E. coli strains. A total of 50 clinical strains of E. coli were collected from urine samples between June 2011 and November 2011. Strains were investigated for the presence of mutations in the chromosomal ampC promoter region by amplification and sequencing of a 271 bp product. The presence of ampC-carrying plasmids derived from other species was also determined, to exclude these from further analysis. ampC-carrying plasmids were found in 10 of the 50 strains, all of which were of the CIT-type. Analysis of the chromosomal ampC promoter region in the 40 remaining strains showed mutations at 16 different positions, with 18 different genotype patterns detected overall. The most common ampC chromosomal mutation, present in 25 of 40 strains, was a T→A transition at position -32. This mutation has been shown by others to increase enzyme production by up to 46-fold. Altogether, three separate mutations (-32, -42 and -13ins) were present in 90% of the 40 non-plasmid strains, indicating a strong association with the resistance observed. It appears, therefore, that the majority of AmpC-mediated resistance in E. coli can be accounted for by just three point mutations in the chromosome
Holographic Technidilaton and LHC searches
We analyze in detail the phenomenology of a model of dynamical electroweak
symmetry breaking inspired by walking technicolor, by using the techniques of
the bottom-up approach to holography. The model admits a light composite scalar
state, the dilaton, in the spectrum. We focus on regions of parameter space for
which the mass of such dilaton is 125 GeV, and for which the bounds on the
precision electroweak parameter S are satisfied. This requires that the
next-to-lightest composite state is the techni-rho meson, with a mass larger
than 2.3 TeV. We compute the couplings controlling the decay rates of the
dilaton to two photons and to two (real or virtual) Z and W bosons. For generic
choices of the parameters, we find a suppression of the decay into heavy gauge
bosons, in respect to the analog decay of the standard-model Higgs. We find a
dramatic effect on the decay into photons, which can be both strongly
suppressed or strongly enhanced, the latter case corresponding to the large-N
regime of the dual theory. There is a correlation between this decay rate of
the dilaton into photons and the mass splitting between the techni-rho meson
and its axial-vector partner: if the decay is enhanced in respect to the
standard-model case, then the heavy spin-1 resonances are nearly degenerate in
mass, otherwise their separation in mass is comparable to the mass scale
itself.Comment: Very minor typos corrected. References adde
Resistance to echinocandin antifungal agents in the United Kingdom in clinical isolates of Candida glabrata: Fifteen years of interpretation and assessment
Candidaemia is widely reported as the fourth most common form of bloodstream infection worldwide. Reports of breakthrough cases of candidaemia are increasing, especially in the context of a move away from azole antifungals as prophylactic or first line treatment towards the use of echinocandin agents. The global evaluation of echinocandin antifungal susceptibility since 2003 has included switches in testing methodologies and the move to a sentinel echinocandin approach for classification reporting. This study compiles previously unpublished data from echinocandin susceptibility testing of UK clinical isolates of C. glabrata received at the Public Health England Mycology Reference Laboratory from 2003 to 2016, and re-evaluates the prevalence of resistance in light of currently accepted testing protocols. From 2015 onwards, FKS gene mutation detection using a novel Pyrosequencing® assay was assessed as a predictor of echinocandin resistance alongside conventional susceptibility testing. Overall, our data show that echinocandin resistance in UK isolates of C. glabrata is a rare phenomenon and prevalence has not appreciably increased in the last 14 years. The pyrosequencing assay was able to successfully detect hot spot mutations in FKS1 and FKS2, although not all isolates that exhibited phenotypic resistance demonstrated detectable hot spot mutations. We propose that a rapid genomic based detection method for FKS mutations, as part of a multifactorial approach to susceptibility testing, could help provide accurate and timely management decisions especially in regions where echinocandin resistance has been reported to be emerging in this important pathogen
Listening to mental health crisis needs at scale: using Natural Language Processing to understand and evaluate a mental health crisis text messaging service
The current mental health crisis is a growing public health issue requiring a large-scale response that cannot be met with traditional services alone. Digital support tools are proliferating, yet most are not systematically evaluated, and we know little about their users and their needs. Shout is a free mental health text messaging service run by the charity Mental Health Innovations, which provides support for individuals in the UK experiencing mental or emotional distress and seeking help. Here we study a large data set of anonymised text message conversations and post-conversation surveys compiled through Shout. This data provides an opportunity to hear at scale from those experiencing distress; to better understand mental health needs for people not using traditional mental health services; and to evaluate the impact of a novel form of crisis support. We use natural language processing (NLP) to assess the adherence of volunteers to conversation techniques and formats, and to gain insight into demographic user groups and their behavioural expressions of distress. Our textual analyses achieve accurate classification of conversation stages (weighted accuracy = 88%), behaviours (1-hamming loss = 95%) and texter demographics (weighted accuracy = 96%), exemplifying how the application of NLP to frontline mental health data sets can aid with post-hoc analysis and evaluation of quality of service provision in digital mental health services
Exact Analytical Bit Error Rates for Multiple Access Chaos-Based Communication Systems
Ab initio calculations of stationary points on the benzene-Ar and p-difluorobenzene-Ar potential energy surfaces: barriers to bound orbiting states
The potential energy surfaces of the van der Waals complexes benzene–Ar and p-difluorobenzene– Ar have been investigated at the second-order Møller–Plesset (MP2) level of theory with the aug-cc-pVDZ basis set. Calculations were performed with unconstrained geometry optimization for all stationary points. This study has been performed to elucidate the nature of a conflict between experimental results from dispersed fluorescence and velocity map imaging (VMI). The inconsistency is that spectra for levels of p-difluorobenzene–Ar and –Kr below the dissociation thresholds determined by VMI show bands where free p-difluorobenzene emits, suggesting that dissociation is occurring. We proposed that the bands observed in the dispersed fluorescence spectra are due to emission from states in which the rare gas atom orbits the aromatic chromophore; these states are populated by intramolecular vibrational redistribution from the initially excited level [S. M. Bellm, R. J. Moulds, and W. D. Lawrance, J. Chem. Phys. 115, 10709 (2001)]. To test this proposition, stationary points have been located on both the benzene–Ar and p-difluorobenzene–Ar potential energy surfaces (PESs) to determine the barriers to this orbiting motion. Comparison with previous single point CCSD(T) calculations of the benzene–Ar PES has been used to determine the amount by which the barriers are overestimated at the MP2 level. As there is little difference in the comparable regions of the benzene–Ar and p-difluorobenzene–Ar PESs, the overestimation is expected to be similar for p-difluorobenzene–Ar. Allowing for this overestimation gives the barrier to movement of the Ar atom around the pDFB ring via the valley between the H atoms as [less than or equal to] 204 cm⁻¹ in So (including zero point energy). From the estimated change upon electronic excitation, the corresponding barrier in S1 is estimated to be [less than or equal to] 225 cm⁻¹. This barrier is less than the 240 cm⁻¹ energy of 30², the vibrational level for which the anomalous "free p-difluorobenzene" bands were observed in dispersed fluorescence from p-difluorobenzene–Ar, supporting our hypothesis for the origin of these bands.Rebecca J. Moulds, Mark A. Buntine and Warren D. Lawranc
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