1,870 research outputs found
The high-lying Li levels at excitation energy around 21 MeV
The H+He cluster structure in Li was investigated by the
H(,H He)n kinematically complete experiment at the incident
energy = 67.2 MeV. We have observed two resonances at =
21.30 and 21.90 MeV which are consistent with the He(H, )Li
analysis in the Ajzenberg-Selove compilation. Our data are compared with the
previous experimental data and the RGM and CSRGM calculations.Comment: 12 pages, 6 figures. Accepted for publication in J. Phys. Soc. Jp
The development of a new measure of quality of life for children with congenital cardiac disease
The purpose of the study was to develop a questionnaire measuring health-related R1 quality of life for children and adolescents with congenital heart disease, the ConQol, that would have both clinical and research applications. We describe here the process of construction of a questionnaire, the piloting and the development of a weighted scoring system, and data on the psychometric performance of the measure in a sample of 640 children and young people recruited via 6 regional centres for paediatric cardiology from across the United Kingdom. The ConQol has two versions, one designed for children aged from 8 to 11 years, and the other for young people aged from 12 to 16 years. Initial findings suggest that it is a valid and reliable instrument, is acceptable to respondents, and is simple to administer in both a research and clinical context
Low-loss criterion and effective area considerations for photonic crystal fibers
We study the class of endlessly single-mode all-silica photonic crystal
fibers with a triangular air-hole cladding. We consider the sensibility to
longitudinal nonuniformities and the consequences and limitations for realizing
low-loss large-mode area photonic crystal fibers. We also discuss the
dominating scattering mechanism and experimentally we confirm that both macro
and micro-bending can be the limiting factor.Comment: Accepted for Journal of Optics A - Pure and Applied Optic
Macrofossils and pollen representing forests of the pre-Taupo volcanic eruption (c. 1850 yr BP) era at Pureora and Benneydale, central North Island, New Zealand.
Micro- and macrofossil data from the remains of forests overwhelmed and buried at Pureora and Benneydale during the Taupo eruption (c. 1850 conventional radiocarbon yr BP) were compared. Classification of relative abundance data separated the techniques, rather than the locations, because the two primary clusters comprised pollen and litter/wood. This indicates that the pollen:litter/wood within-site comparisons (Pureora and Benneydale are 20 km apart) are not reliable. Plant macrofossils represented mainly local vegetation, while pollen assemblages represented a combination of local and regional vegetation. However, using ranked abundance and presence/absence data, both macrofossils and pollen at Pureora and Benneydale indicated conifer/broadleaved forest, of similar forest type and species composition at each site. This suggests that the forests destroyed by the eruption were typical of mid-altitude west Taupo forests, and that either data set (pollen or macrofossils) would have been adequate for regional forest interpretation.
The representation of c. 1850 yr BP pollen from the known buried forest taxa was generally consistent with trends determined by modern comparisons between pollen and their source vegetation, but with a few exceptions.
A pollen profile from between the Mamaku Tephra (c. 7250 yr BP) and the Taupo Ignimbrite indicated that the Benneydale forest had been markedly different in species dominance compared with the forest that was destroyed during the Taupo eruption. These differences probably reflect changes in drainage, and improvements in climate and/or soil fertility over the middle Holocene
Mitigating housing market shocks: an agent-based reinforcement learning approach with implications for real-time decision support
Research in modelling housing market dynamics using agent-based models (ABMs) has grown due to the rise of accessible individual-level data. This research involves forecasting house prices, analysing urban regeneration, and the impact of economic shocks. There is a trend towards using machine learning (ML) algorithms to enhance ABM decision-making frameworks. This study investigates exogenous shocks to the UK housing market and integrates reinforcement learning (RL) to adapt housing market dynamics in an ABM. Results show agents can learn real-time trends and make decisions to manage shocks, achieving goals like adjusting the median house price without pre-determined rules. This model is transferable to other housing markets with similar complexities. The RL agent adjusts mortgage interest rates based on market conditions. Importantly, our model shows how a central bank agent learned conservative behaviours in sensitive scenarios, aligning with a 2009 study, demonstrating emergent behavioural patterns
Nonlinear transmission through a tapered fiber in rubidium vapor
Sub-wavelength diameter tapered optical fibers surrounded by rubidium vapor
can undergo a substantial decrease in transmission at high atomic densities due
to the accumulation of rubidium atoms on the surface of the fiber. Here we
demonstrate the ability to control these changes in transmission using light
guided within the taper. We observe transmission through a tapered fiber that
is a nonlinear function of the incident power. This effect can also allow a
strong control beam to change the transmission of a weak probe beam.Comment: 10 pages, 4 figure
Why Do States Develop Multi-tier Emigrant Policies? Evidence from Egypt
Why do states vary their policies towards their citizens abroad, and why are some emigrant groups treated preferentially to others? The literature on the politics of international migration has yet to explore this as a separate field of inquiry, assuming that states adopt a single policy that encourages, sustains or prevents emigration abroad. Yet, in the case of Egypt, the state developed a multi-tiered policy that distinctly favoured specific communities abroad over others. I hypothesise that policy differentiation is based upon the perceived utility of the emigrant group remaining abroad versus the utility of its return. This utility is determined by two factors: the sending state’s domestic political economy priorities and its foreign policy objectives
The politics of protest in newspaper campaigns: dissent, populism and the rhetoric of authenticity
Newspaper campaigns embody newspaper’ most emphatic claims to speak for ‘the people’, and as such are generally regarded as populist. However, they can be oppositional, engaging in dissent of one sort or another, and often assume a certain amount of political engagement with that dissent on the part of the audience. This article examines the potential of newspaper camapigns to facilitate the political engagement of citizens through the politics of protest. It draws on qualitative analysis of seven campaigns that ran in the Scottish press between 2000 and 2005, and semi-structured interviews with relevant journalists. The distinction between legitimate protest and manipulative populism is made in terms of: (a) the rhetoric and strategies of political representation, participation and influence and (b) the construction of political legitimacy in terms of the public interest and the moral authority of the ‘victim’. It is argued that populist impulses dominate, driving a tendency to use discourses of emotional authenticity and offence to legitimise demands for a plebiscitary response to popular of ‘victim’ preference and to close down controversy and debate, with the principal objective marketing the newspaper as an influential community champion
Methodological bias in cluster randomised trials
Background: Cluster randomised trials can be susceptible to a range of methodological problems. These problems are not commonly recognised by many researchers. In this paper we discuss the issues that can lead to bias in cluster trials. Methods: We used a sample of cluster randomised trials from a recent review and from a systematic review of hip protectors. We compared the mean age of participants between intervention groups in a sample of 'good' cluster trials with a sample of potentially biased trials. We also compared the effect sizes, in a funnel plot, between hip protector trials that used individual randomisation compared with those that used cluster randomisation. Results: There is a tendency for cluster trials, with evidence methodological biases, to also show an age imbalance between treatment groups. In a funnel plot we show that all cluster trials show a large positive effect of hip protectors whilst individually randomised trials show a range of positive and negative effects, suggesting that cluster trials may be producing a biased estimate of effect. Conclusion: Methodological biases in the design and execution of cluster randomised trials is frequent. Some of these biases associated with the use of cluster designs can be avoided through careful attention to the design of cluster trials. Firstly, if possible, individual allocation should be used. Secondly, if cluster allocation is required, then ideally participants should be identified before random allocation of the clusters. Third, if prior identification is not possible, then an independent recruiter should be used to recruit participants
Optical nanofibers and spectroscopy
We review our recent progress in the production and characterization of
tapered optical fibers with a sub-wavelength diameter waist. Such fibers
exhibit a pronounced evanescent field and are therefore a useful tool for
highly sensitive evanescent wave spectroscopy of adsorbates on the fiber waist
or of the medium surrounding. We use a carefully designed flame pulling process
that allows us to realize preset fiber diameter profiles. In order to determine
the waist diameter and to verify the fiber profile, we employ scanning electron
microscope measurements and a novel accurate in situ optical method based on
harmonic generation. We use our fibers for linear and non-linear absorption and
fluorescence spectroscopy of surface-adsorbed organic molecules and investigate
their agglomeration dynamics. Furthermore, we apply our spectroscopic method to
quantum dots on the surface of the fiber waist and to caesium vapor surrounding
the fiber. Finally, towards dispersive measurements, we present our first
results on building and testing a single-fiber bi-modal interferometer.Comment: 13 pages, 18 figures. Accepted for publication in Applied Physics B.
Changes according to referee suggestions: changed title, clarification of
some points in the text, added references, replacement of Figure 13
- …