1,194 research outputs found
Contemporaneous late cretaceous calc-alkaline and alkaline magmatism in Central Anatolia, Turkey: oxygen isotope constraints on petrogenesis
A wide variety of rock types were produced by the latest Cretaceous magmatism in the Central Anatolian Crystalline Complex. These rocks can be divided into three distinct units: (i) calc-alkaline, (ii) subalkaline/transitional,
and (iii) alkaline. The calc-alkaline rocks are mainly metaluminous (I-type) ranging from monzodiorite to granite. The subalkaline/transitional rocks are also metaluminous (I-type) ranging from monzonite to granite. The alkaline rocks are mainly peralkaline (A-type), ranging from feldspathoid-bearing monzosyenite to granite. Whole-rock oxygen isotope data from the complex have a considerable range of ÎŽ18O values between 6.5â° and 14.8â°. Initial 87Sr/86Sr versus 143Nd/144Nd ratios, and both ratios versus ÎŽ18O values diagrams show that the intrusive rocks are derived from a subduction-modified mantle and also have experienced fractional crystallisation coupled with crustal assimilation. Delamination of a thermal boundary layer, and/or slab breakoff is the likely mechanisms for the initiation of the diverse magmatism in the complex
A relativistic dynamical model for pi-N scattering
We present a unitary relativistic quasi-potential model for describing the
low-energy pion-nucleon interaction, based on the equal time Bethe-Salpeter
equation. It preserves the covariant structure of a relativistic spin 1/2
particle for the nucleon propagator, to be contrasted to other quasi-potential
approximations.Comment: 4 pages, Latex2e. To appear in the Proceedings of XV Int. Conf. on
Few-Body Problems in Physics (Groningen, July 1997
Composition and evolution of the Ancestral South Sandwich Arc: implications for the flow of deep ocean water and mantle through the Drake Passage gateway
The Ancestral South Sandwich Arc (ASSA) has a short life-span of c.20 m.y. (Early Oligocene to Middle-Upper Miocene) before slab retreat and subsequent âresurrectionâ as the active South Sandwich Island Arc (SSIA). The ASSA is, however, significant because it straddled the eastern margin of the Drake Passage Gateway where it formed a potential barrier to deep ocean water and mantle flow from the Pacific to Atlantic. The ASSA may be divided into three parts, from north to south: the Central Scotia Sea (CSS), the Discovery segment, and the Jane segment. Published age data coupled with new geochemical data (major elements, trace elements, Hf-Nd-Sr-Pb isotopes) from the three ASSA segments place constraints on models for the evolution of the arc and hence gateway development. The CSS segment has two known periods of activity. The older, Oligocene, period produced basic-acid, mostly calc-alkaline rocks, best explained in terms of subduction initiation volcanism of Andean-type (no slab rollback). The younger, Middle-Late Miocene period produced basic-acid, high-K calc-alkaline rocks (lavas and pyroclastic rocks with abundant volcanigenic sediments) which, despite being erupted on oceanic crust, have continental arc characteristics best explained in terms of a large, hot subduction flux most typical of a syn- or post-collision arc setting. Early-Middle Miocene volcanism in the Discovery and Jane arc segments is geochemically quite different, being typically tholeiitic and compositionally similar to many lavas from the active South Sandwich island arc front. There is indirect evidence for Western Pacific-type (slab rollback) subduction initiation in the southern part of the ASSA and for the back-arc basins (the Jane and Scan Basins) to have been active at the time of arc volcanism. Models for the death of the ASSA in the south following a series of ridge-trench collisions, are not positively supported by any geochemical evidence of hot subduction, but cessation of subduction by approach of progressively more buoyant oceanic lithosphere is consistent with both geochemistry and geodynamics. In terms of deep ocean water flow the early stages of spreading at the East Scotia Ridge (starting at 17-15 Ma) may have been important in breaking up the ASSA barrier while the subsequent establishment of a STEP (Subduction-Transform Edge Propagator) fault east of the South Georgia microcontinent (< 11 Ma) led to formation of the South Georgia Passage used by the Antarctic Circumpolar Current today. In terms of mantle flow, the subduction zone and arc root likely acted as a barrier to mantle flow in the CSS arc segment such that the ASSA itself became the Pacific-South Atlantic mantle domain boundary. This was not the case in the Discovery and Jane arc segments, however, because northwards flow of South Atlantic mantle behind the southern part of the ASSA gave an Atlantic provenance to the whole southern ASSA
Factors associated with universal infant free school meal take up and refusal in a multicultural urban community
BackgroundUniversal infant free school meals (UIFSM) were introduced in September 2014 and are available to all key stage 1 (4â7 years) children attending state-maintained infant and primary schools in England. The present study aimed to investigate the school-based factors, child and family socio-demographic characteristics, and parental beliefs associated with UIFSM take up in an urban community.MethodsA cross-sectional questionnaire survey was completed in October to November 2015, amongst parents whose children attended eligible schools in Leicester, England. A questionnaire about school meals was also completed by each school.ResultsParents reported their child did not take (non-UIFSM, n = 159) or took (UIFSM, n = 517) a UIFSM on most days. The non-UIFSM group were more likely to be White-British, have a higher socio-economic status, have English as a first language, and involve their child in the decision over whether or not to take UIFSM, compared to the UIFSM group. Cluster analysis revealed that non-UIFSM parents were either concerned over quality of meals and what/how much their child ate, concerned only by what/how much their child ate or whether their child did not like the food provided. Two subsets of parents in the UIFSM group were either very positive about UIFSM or appeared to take meals because they were free. Schools used a variety of measures to increase and maintain UIFSM take up.ConclusionsParents like to have control over what their child eats at school and children need to enjoy their school meals. Using a range of interventions to target subsets of parents may help local authorities, schools and caterers to increase UIFSM take up
Dynamical aspects of mean field plane rotators and the Kuramoto model
The Kuramoto model has been introduced in order to describe synchronization
phenomena observed in groups of cells, individuals, circuits, etc... We look at
the Kuramoto model with white noise forces: in mathematical terms it is a set
of N oscillators, each driven by an independent Brownian motion with a constant
drift, that is each oscillator has its own frequency, which, in general,
changes from one oscillator to another (these frequencies are usually taken to
be random and they may be viewed as a quenched disorder). The interactions
between oscillators are of long range type (mean field). We review some results
on the Kuramoto model from a statistical mechanics standpoint: we give in
particular necessary and sufficient conditions for reversibility and we point
out a formal analogy, in the N to infinity limit, with local mean field models
with conservative dynamics (an analogy that is exploited to identify in
particular a Lyapunov functional in the reversible set-up). We then focus on
the reversible Kuramoto model with sinusoidal interactions in the N to infinity
limit and analyze the stability of the non-trivial stationary profiles arising
when the interaction parameter K is larger than its critical value K_c. We
provide an analysis of the linear operator describing the time evolution in a
neighborhood of the synchronized profile: we exhibit a Hilbert space in which
this operator has a self-adjoint extension and we establish, as our main
result, a spectral gap inequality for every K>K_c.Comment: 18 pages, 1 figur
Public health strategies to reduce sugar intake in the UK: an exploration of public perceptions using digital spaces
Background: To explore UK public perceptions of childrenâs sugar consumption, Public Health Englandâs Change4Life Sugar Smart App and the Soft Drinks Industry Levy, using solicited and unsolicited digital data.
Methods: Data from three digital spaces were used: (1) an online questionnaire advertised on parenting forums; (2) posts to UK online parenting forums; (3) English-language Tweets from Twitter. Quantitative data were analysed using descriptive statistics and qualitative data using content and inductive thematic analysis.
Results: Data were (study 1) 184 questionnaire participants; (study 2) 412 forum posts; (study 3) 618 Tweets. In study 1, 94.0% (n=173) agreed that children in the UK consumed too much sugar and this had a negative health effect (98.4%, n=181). Environments (n=135, 73.4%), media/advertising (n=112, 60.9%), and parents (n=107, 58.2%) were all reported as barriers to changing childrenâs sugar intake. In study 2, more posts were negative towards the Soft Drinks Industry Levy (n=189, 45.9%) than positive (n=145, 35.2%), and themes about the inability of the Levy to affect sugar consumption in children and childhood obesity emerged. Other themes related to distrust of the government, food industry and retailers. In study 3, the Sugar Smart App was viewed positively (n=474, 76.7%) with its function associated solely with identification of sugar content.
Conclusions: Participants accepted the necessity of sugar reduction in children, but recognised the complexity of behaviour change. Public health activities were not always perceived as effective strategies for health promotion. There was some distrust in government, public health officials, and the food industry. A less simplistic approach to sugar reduction and more credible sources of information may, therefore, be welcomed by the public
The NICE COVIDâ19 rapid guideline on haematopoietic stem cell transplantation: development, implementation and impact
A new coronavirus SARSâCoVâ2 emerged at the start of 2020 with rapid worldwide spread. It is the causative agent of Coronavirus Disease 2019 (COVIDâ19). The resulting pandemic has been challenging for centres undertaking autologous and allogeneic haematopoietic stem cell transplants (HSCT). One of the main risks in HSCT is infection susceptibility, including viral infections, which are often more severe and lifeâthreatening.1
In response to the COVIDâ19 pandemic, the National Institute for Health and Care Excellence (NICE) published the first version of the COVIDâ19 rapid guideline for HSCT (NG164) on 1 April 20202; this was updated on 29 July 2020 in response to the changing context of the pandemic. The British Society of Blood and Marrow Transplantation and Cellular Therapy (BSBMTCT) and the European Society for Blood and Marrow Transplantation (EBMT) also developed detailed guidance to support transplant centres.3-5
This paper describes the development and update processes for NICE NG164, detailing the rationale behind the recommendations, implementation and the impact of COVIDâ19 on HSCT activity in the UK compared with 2019, based on registrations in the BSBMTCT registry. The full NICE guidance can be obtained from: https://www.nice.org.uk/guidance/ng164
Vector meson production and nucleon resonance analysis in a coupled-channel approach for energies m_N < sqrt(s) < 2 GeV II: photon-induced results
We present a nucleon resonance analysis by simultaneously considering all
pion- and photon-induced experimental data on the final states gamma N, pi N, 2
pi N, eta N, K Lambda, K Sigma, and omega N for energies from the nucleon mass
up to sqrt(s) = 2 GeV. In this analysis we find strong evidence for the
resonances P_{31}(1750), P_{13}(1900), P_{33}(1920), and D_{13}(1950). The
omega N production mechanism is dominated by large P_{11}(1710) and
P_{13}(1900) contributions. In this second part we present the results on the
photoproduction reactions and the electromagnetic properties of the resonances.
The inclusion of all important final states up to sqrt(s) = 2 GeV allows for
estimates on the importance of the individual states for the GDH sum rule.Comment: 41 pages, 26 figures, discussion extended, typos corrected,
references updated, to appear in Phys. Rev.
Photometric Observation And Period Study of GO Cygni
Photometric observations of GO Cyg were performed during the July-October
2002, in B and V bands of Johnson system. Based on Wilson's model, the light
curve analysis were carried out to find the photometric elements of the system.
The O-C diagram which is based on new observed times of minima suggests a
negative rate of period variation (dP/dt<0) for the system.Comment: 12 pages, 6 figures, 4 tables, submitted to Ap&S
flavour tagging using charm decays at the LHCb experiment
An algorithm is described for tagging the flavour content at production of
neutral mesons in the LHCb experiment. The algorithm exploits the
correlation of the flavour of a meson with the charge of a reconstructed
secondary charm hadron from the decay of the other hadron produced in the
proton-proton collision. Charm hadron candidates are identified in a number of
fully or partially reconstructed Cabibbo-favoured decay modes. The algorithm is
calibrated on the self-tagged decay modes and using of data collected by the LHCb
experiment at centre-of-mass energies of and
. Its tagging power on these samples of
decays is .Comment: All figures and tables, along with any supplementary material and
additional information, are available at
http://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-027.htm
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