11,811 research outputs found
Remarks on separating words
The separating words problem asks for the size of the smallest DFA needed to
distinguish between two words of length <= n (by accepting one and rejecting
the other). In this paper we survey what is known and unknown about the
problem, consider some variations, and prove several new results
Is child weight status correctly reported to parents? Cross-sectional analysis of National Child Measurement Programme data using ethnic-specific BMI adjustments.
BACKGROUND: BMI underestimates and overestimates body fat in children from South Asian and Black ethnic groups, respectively. METHODS: We used cross-sectional NCMP data (2015-17) for 38 270 children in three inner-London local authorities: City & Hackney, Newham and Tower Hamlets (41% South Asian, 18.8% Black): 20 439 4-5 year-olds (48.9% girls) and 17 831 10-11 year-olds (49.1% girls). We estimated the proportion of parents who would have received different information about their child's weight status, and the area-level prevalence of obesity-defined as ≥98th centile-had ethnic-specific BMI adjustments been employed in the English National Child Measurement Programme (NCMP). RESULTS: Had ethnic-specific adjustment been employed, 19.7% (3112/15 830) of parents of children from South Asian backgrounds would have been informed that their child was in a heavier weight category, and 19.1% (1381/7217) of parents of children from Black backgrounds would have been informed that their child was in a lighter weight category. Ethnic-specific adjustment increased obesity prevalence from 7.9% (95% CI: 7.6, 8.3) to 9.1% (8.7, 9.5) amongst 4-5 year-olds and from 17.5% (16.9, 18.1) to 18.8% (18.2, 19.4) amongst 10-11 year-olds. CONCLUSIONS: Ethnic-specific adjustment in the NCMP would ensure equitable categorization of weight status, provide correct information to parents and support local service provision for families
Mammographic image restoration using maximum entropy deconvolution
An image restoration approach based on a Bayesian maximum entropy method
(MEM) has been applied to a radiological image deconvolution problem, that of
reduction of geometric blurring in magnification mammography. The aim of the
work is to demonstrate an improvement in image spatial resolution in realistic
noisy radiological images with no associated penalty in terms of reduction in
the signal-to-noise ratio perceived by the observer. Images of the TORMAM
mammographic image quality phantom were recorded using the standard
magnification settings of 1.8 magnification/fine focus and also at 1.8
magnification/broad focus and 3.0 magnification/fine focus; the latter two
arrangements would normally give rise to unacceptable geometric blurring.
Measured point-spread functions were used in conjunction with the MEM image
processing to de-blur these images. The results are presented as comparative
images of phantom test features and as observer scores for the raw and
processed images. Visualization of high resolution features and the total image
scores for the test phantom were improved by the application of the MEM
processing. It is argued that this successful demonstration of image
de-blurring in noisy radiological images offers the possibility of weakening
the link between focal spot size and geometric blurring in radiology, thus
opening up new approaches to system optimization.Comment: 18 pages, 10 figure
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How robust are the surface temperature fingerprints of the Atlantic Overturning Meridional Circulation on monthly time‐scales?
It has been suggested that changes in the Atlantic Meridional Overturning Circulation (AMOC) can drive sea surface temperature (SST) on monthly timescales [Duchez et al., 2016]. However, with only 11 years of continuous observations, the validity of this result over longer, or different, time‐periods is uncertain. In this study, we use a 120‐yr long control simulation from a high‐resolution climate model to test the robustness of the AMOC fingerprints. The model reproduces the observed AMOC seasonal cycle and its variability, and the observed 5‐month lagged AMOC‐SST fingerprints derived from 11‐years of data. However, the AMOC‐SST fingerprints are very sensitive to the particular time‐period considered. In particular, both the Florida current and the upper mid ocean transport produce highly inconsistent fingerprints when using time‐periods shorter than 30 years. Therefore, several decades of RAPID observations will be necessary to determine the real impact of the AMOC on SSTs at monthly time‐scales
Cadmium contamination of agricultural soils and crops resulting from sphalerite weathering.
The biogeochemistry and bioavailability of cadmium, released during sphalerite weathering in soils, were investigated under contrasting agricultural scenarios to assess health risks associated with sphalerite dust transport to productive soils from mining. Laboratory experiments (365 d) on temperate and sub-tropical soils amended with sphalerite (<63 μm, 0.92 wt.% Cd) showed continuous, slow dissolution (0.6-1.2% y(-1)). Wheat grown in spiked temperate soil accumulated ≈38% (29 μmol kg(-1)) of the liberated Cd, exceeding food safety limits. In contrast, rice grown in flooded sub-tropical soil accumulated far less Cd (0.60 μmol kg(-1)) due to neutral soil pH and Cd bioavailability was possibly also controlled by secondary sulfide formation. The results demonstrate long-term release of Cd to soil porewaters during sphalerite weathering. Under oxic conditions, Cd may be sufficiently bioavailable to contaminate crops destined for human consumption; however flooded rice production limits the impact of sphalerite contamination
A last millennium perspective on North Atlantic variability: exploiting synergies between models and proxy data
The North Atlantic is a key region for decadal prediction
as it has experienced significant multi-decadal variability
over the observed period. This variability, which is
thought to be intrinsic to the region, can potentially
modulate, either by amplifying or mitigating, the
global warming signal from anthropogenic greenhouse
emissions. For example, studies suggest that the North
Atlantic contributed to the recent hiatus period between
1998 and 2012, by triggering an atmospheric response
which impacted on the eastern tropical Pacific (e.g.
McGregor et al., 2014). The subpolar North Atlantic is
also a major CO2
sink, and therefore of great importance
for the global carbon cycle (Perez et al., 2013).
One of the key players in the North Atlantic region is the
Atlantic Meridional Overturning Circulation (AMOC),
which is associated with sinking due to deep water
formation in the Labrador and Nordic Seas. The AMOC is
the primary control of the poleward heat transport in the
Atlantic region. Therefore, the AMOC is associated with
important climate impacts, and plays an active role in
various feedback mechanisms with, for example, sea ice
(Mahajan et al., 2011) and the atmospheric circulation
(Gastineau and Frankignoul, 2012). The AMOC has
exhibited abrupt variations in the past (e.g. the last glacial
period, Rahmstorf, 2002) and could experience a major
slowdown in the future due to the combined effect of
surface warming and Greenland ice sheet melting on deep
water formation (Bakker et al., 2016). The possibility
of such a shutdown has stimulated considerable
international efforts to observe and reconstruct the
past AMOC changes. Only by understanding its natural
variability will we be able to detect and anticipate an
anthropogenic impact on the AMOC.
Decadal modulations are also found in other large-scale
modes of climate variability, such as the North Atlantic
Oscillation (NAO) (Stephenson et al., 2000), the Subpolar
Gyre strength (SPG) (Häkkinen and Rhines, 2004) and
the Atlantic Multidecadal Variability (AMV) (Enfield et al.,
2001), which have all been linked with widespread climate
impacts over the surrounding continents. Modelling
studies suggest that all these modes interact with the
AMOC (Gastineau and Frankignoul, 2012; Hátún et al.,
2005; Knight et al., 2005) but the exact interrelationships
are complex and remain to be disentangled. Also to be
determined are the underlying mechanisms responsible
for the decadal and centennial AMOC modulations, with
different climate models showing different key drivers
(Menary et al., 2015a). Similarly, the exact impact of the
natural external forcings (e.g. volcanic aerosols, solar
irradiance) on the variability of these different largescale
climate modes still remains unclear
Multiple case-study analysis of quality management practices within UK Six Sigma and non-Six Sigma manufacturing small- and medium-sized enterprises
This paper examines multiple case-study analysis of quality management practices within UK Six Sigma and non-Six Sigma manufacturing small- and medium-sized enterprises
Modeling of the Thermal Field in Dissimilar Alloy Ultrasonic Welding
This paper describes a finite element model for predicting the temperature field in high power ultrasonic welding aluminum AA6111 to two dissimilar alloys, magnesium AZ31, and low carbon steel DC04. Experimental thermocouple and other evidence are used to infer the magnitude and distribution of the heat input to the workpiece, as a function of time, for each of the material combinations welded. The resulting temperature histories are used to predict the growth of intermetallic phases at the interface in Al-Mg welds. The microstructural model successfully predicts the thickness of the intermetallic layer, but the sensitivity of the results to temperature is demonstrated.The work described in this paper was funded by the UK
Engineering and Physical Sciences Research Council (EPSRC) via
the following grants: Friction Joining - Low Energy Manufacturing
for Hybrid Structures in Fuel Efficient Transport Applications (EP/
G022402/1 and EP/G022674/1), and LATEST 2: Light Alloys
Towards Environmentally Sustainable Transport, 2nd Generation
Solutions for Advanced Metallic Systems (EP/H020047/1). Mr.
Jedrasiak is also supported by EPSRC through the University of
Cambridge Doctoral Training Account, with additional CASE
award funding provided by TWI, Granta Park, Cambridge, UK.This is the final published version. It first appeared at: http://link.springer.com/article/10.1007%2Fs11665-014-1342-8. This paper was published in Journal of Materials Engineering and Performance Volume 24, Issue 2, pp 799-807 and is made available as an electronic reprint with the permission of ASM International. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplications of any material in this paper for a fee or for commercial purposes, or modification of the content of this paper are prohibited
A historic jet-emission minimum reveals hidden spectral features in 3C 273
Aims. The aim of this work is to identify and study spectral features in the
quasar 3C 273 usually blended by its strong jet emission. Method. A historic
minimum in the sub-millimetre emission of 3C 273 triggered coordinated
multi-wavelength observations in June 2004. X-ray observations from the
INTEGRAL, XMM-Newton and RXTE satellites are complemented by ground-based
optical, infrared, millimetre and radio observations. The overall spectrum is
used to model the infrared and X-ray spectral components. Results. Three
thermal dust emission components are identified in the infrared. The dust
emission on scales from 1 pc to several kpc is comparable to that of other
quasars, as expected by AGN unification schemes. The observed weakness of the
X-ray emission supports the hypothesis of a synchrotron self-Compton origin for
the jet component. There is a clear soft-excess and we find evidence for a very
broad iron line which could be emitted in a disk around a Kerr black hole.
Other signatures of a Seyfert-like X-ray component are not detected.Comment: 4 pages. Accepted for publication in A&A Letter
Proteomic identification of heterogeneous nuclear ribonucleoprotein L as a novel component of SLM/Sam68 nuclear bodies
Background: Active pre-mRNA splicing occurs co-transcriptionally, and takes place throughout the nucleoplasm of eukaryotic cells. Splicing decisions are controlled by networks of nuclear RNA-binding proteins and their target sequences, sometimes in response to signalling pathways. Sam68 (Src-associated in mitosis 68 kDa) is the prototypic member of the STAR (Signal Transduction and Activation of RNA) family of RNA-binding proteins, which regulate splicing in response to signalling cascades. Nuclear Sam68 protein is concentrated within subnuclear organelles called SLM/Sam68 Nuclear Bodies (SNBs), which also contain some other splicing regulators, signalling components and nucleic acids.
Results: We used proteomics to search for the major interacting protein partners of nuclear Sam68. In addition to Sam68 itself and known Sam68-associated proteins (heterogeneous nuclear ribonucleoproteins hnRNP A1, A2/B1 and G), we identified hnRNP L as a novel Sam68-interacting protein partner. hnRNP L protein was predominantly present within small nuclear protein complexes approximating to the expected size of monomers and dimers, and was quantitatively associated with nucleic acids. hnRNP L spatially co-localised with Sam68 as a novel component of SNBs and was also observed within the general nucleoplasm. Localisation within SNBs was highly specific to hnRNP L and was not shared by the closely-related hnRNP LL protein, nor any of the other Sam68-interacting proteins we identified by proteomics. The interaction between Sam68 and hnRNP L proteins was observed in a cell line which exhibits low frequency of SNBs suggesting that this association also takes place outside SNBs. Although ectopic expression of hnRNP L and Sam68 proteins independently affected splicing of CD44 variable exon v5 and TJP1 exon 20 minigenes, these proteins did not, however, co-operate with each other in splicing regulation of these target exons.
Conclusion: Here we identify hnRNP L as a novel SNB component. We show that, compared with other identified Sam68-associated hnRNP proteins and hnRNP LL, this co-localisation within SNBs is specific to hnRNP L. Our data suggest that the novel Sam68-hnRNP L protein interaction may have a distinct role within SNBs
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