9,079 research outputs found
On the fine structure of medium energy electron fluxes in the auroral zone and related effects in the ionospheric D-region
This study is based on measurements of trapped and precipitated electrons of energy >30 keV and >100 keV observed by
polar orbiting environmental satellites during overpasses of the imaging riometer at KilpisjÀrvi, Finland.
The satellites are in sun-synchronous orbits of about 850 km altitude, recording the electron fluxes at 2-s time resolution.
The riometer measures the radiowave absorption at 38.2 MHz, showing the spatial pattern within a 240 km field of view.
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The analysis has focussed on two areas.
Having found a close correlation between the radiowave absorption and the medium-energy electron fluxes during satellite overpasses,
empirical relationships are derived, enabling one quantity to be predicted from the other for three sectors of local time.
It is shown that small-scale variations observed during a pass are essentially spatial rather than temporal.
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Other properties, such as the spectra and the relation between precipitated and trapped components, are also considered in the light of the theory
of pitch angle scattering by VLF waves.
It is found that the properties and behaviour depend strongly on the time of day.
In the noon sector, the precipitated and trapped fluxes are highly correlated through a square law relationship
Lithium : old & new uses in medicine
Lithium has been used in psychiatry since 1949, and since the mid 1960s its use has escalated until it is estimated that about 500,000 patients receive it world-wide. During the last decade a new phase of interest in lithium has begun. Lithium is being used with beneficial effects as a treatment in other health related problems unrelated to psychiatry.peer-reviewe
A critical review of the experimental data for developed free turbulent shear layers
Experimental shear layer data are reviewed and the results are compared to numerical predictions for three test cases. It was concluded from the study that many, if not most, of the apparent inconsistencies which exist in the interpretation of the experimental data for free shear layers result from confusing data taken in developed turbulent flows with those taken in transitional or developing flows. Other conclusions drawn from the study include the following: (1) The effects of Mach number are more uncertain primarily because of limited data and the absence of any turbulence measurements for supersonic shear layers. (2) The data available for heterogeneous shear layers are not sufficient to clearly establish the effect of density ratio on mixing rate
K-Rational D-Brane Crystals
In this paper the problem of constructing spacetime from string theory is
addressed in the context of D-brane physics. It is suggested that the knowledge
of discrete configurations of D-branes is sufficient to reconstruct the motivic
building blocks of certain Calabi-Yau varieties. The collections of D-branes
involved have algebraic base points, leading to the notion of K-arithmetic
D-crystals for algebraic number fields K. This idea can be tested for D0-branes
in the framework of toroidal compactifications via the conjectures of Birch and
Swinnerton-Dyer. For the special class of D0-crystals of Heegner type these
conjectures can be interpreted as formulae that relate the canonical Neron-Tate
height of the base points of the D-crystals to special values of the motivic
L-function at the central point. In simple cases the knowledge of the
D-crystals of Heegner type suffices to uniquely determine the geometry.Comment: 36 page
Tyrosine photophysics during the early stages of ÎČ-amyloid aggregation leading to Alzheimer's
We have monitored the formation of toxic ÎČ-amyloid oligomers leading to Alzheimer's disease by detecting changes in the fluorescence decay of intrinsic tyrosine. A new approach based on the non-Debye model of fluorescence kinetics resolves the complexity of the underlying photophysics. The gradual disappearance of nonmonotonic fluorescence decay rates, at the early stages of aggregation as larger, tighter-packed oligomers are formed, is interpreted in terms of tyrosine-peptide dielectric relaxation influencing the decay. The results demonstrate the potential for a new type of fluorescence lifetime sensing based on dual excited-state/dielectric relaxation, with application across a broad range of biological molecules. The results also reconcile previously conflicting models of protein intrinsic fluorescence decay based on rotamers or dielectric relaxation by illustrating conditions under which both are manifest
Feedback in Online Writing Forums: Effects on Adolescent Writers
Adolescents are writing online. A cursory look at the web reveals that teenagers are well-represented; in blog posts, social media updates, profile pages, comments on YouTube videos, responses to news articles, and websites about their interests, teenagers are writing (Williams 2009). In the current research study, the specific kind of adolescent writing under consideration is writing posted in a social media context designed specifically for writers. This case study focuses on six young writers who are active members of an online writing community, and who post their writing in order to receive feedback. Descriptive data collected through interviews, as well as from samples of writing in the online community provide answers to the research questions: a) Who participates in online writing communities? b) Why do people participate in online writing communities? c) What kind of feedback do members of online writing communities receive on their writing? Educational implications for an informal writing pedagogy, for expanding the notion of âpeerâ in peer feedback, and for valuing students\u27 âout-of-schoolâ writing are discussed
Understanding Motivational Differences through the Lens of Gamification User Types
In the context of an educational technology course, teacher candidates completed Marczewskiâs User Types Hexad Test, a questionnaire based on a typology for classifying both intrinsic and extrinsic motivational tendencies. The test results showed teacher candidates\u27 motivational tendencies, through indicating their resonance with six different User Types, including Socializers, Free Spirits, Achievers, Philanthropists, Players, and Disruptors. Knowing their User Type allowed teacher candidates to reflect on their own personal motivations to use various types of digital tools, as well as to consider how their peers and their students with different user profiles may be motivated differently than themselves. The main research questions in this study were related to discovering the motivational differences present in a group of teacher candidates, and whether knowing about these differences would empower them to acknowledge differences in motivation among their learners. The findings include teacher candidatesâ understandings of the importance of differentiating for motivational tendencies through insight, relationships, and effective teaching, as well the different language teacher candidates use to describe their own developing teacher identity, according to their resonant User Types. These data provide examples of how User Type awareness can help teacher candidates take practical steps toward differentiating instructional design based not only on consideration of learnersâ abilities and interests, but also on learnersâ motivational profiles. Suggestions for language that would resonate with various User Types is presented, and may help teacher educators as they coach pre-service teachers through their identity development
Configurational order-disorder induced metal-nonmetal transition in BC studied with first-principles superatom-special quasirandom structure method
Due to a large discrepancy between theory and experiment, the electronic
character of crystalline boron carbide BC has been a controversial
topic in the field of icosahedral boron-rich solids. We demonstrate that this
discrepancy is removed when configurational disorder is accurately considered
in the theoretical calculations. We find that while ordered ground state
BC is metallic, configurationally disordered BC,
modeled with a superatom-special quasirandom structure method, goes through a
metal to non-metal transition as the degree of disorder is increased with
increasing temperature. Specifically, one of the chain-end carbon atoms in the
CBC chains substitutes a neighboring equatorial boron atom in a B
icosahedron bonded to it, giving rise to a BC(BBC) unit. The
atomic configuration of the substitutionally disordered BC thus
tends to be dominated by a mixture between B(CBC) and
BC(BBC). Due to splitting of valence states in
BC(BBC), the electron deficiency in B(CBC) is gradually
compensated
Acupuncture for chronic neck pain: a pilot for a randomised controlled trial
Background: Acupuncture is increasingly being used for many conditions including chronic neck pain. However the evidence remains inconclusive, indicating the need for further well-designed research. The aim of this study was to conduct a pilot randomised controlled parallel arm trial, to establish key features required for the design and implementation of a large-scale trial on acupuncture for chronic neck pain. Methods: Patients whose GPs had diagnosed neck pain were recruited from one general practice, and randomised to receive usual GP care only, or acupuncture ( up to 10 treatments over 3 months) as an adjunctive treatment to usual GP care. The primary outcome measure was the Northwick Park Neck Pain Questionnaire (NPQ) at 3 months. The primary analysis was to determine the sample size for the full scale study. Results: Of the 227 patients with neck pain identified from the GP database, 28 (12.3%) consenting patients were eligible to participate in the pilot and 24 (10.5%) were recruited to the trial. Ten patients were randomised to acupuncture, receiving an average of eight treatments from one of four acupuncturists, and 14 were randomised to usual GP care alone. The sample size for the full scale trial was calculated from a clinically meaningful difference of 5% on the NPQ and, from this pilot, an adjusted standard deviation of 15.3%. Assuming 90% power at the 5% significance level, a sample size of 229 would be required in each arm in a large-scale trial when allowing for a loss to follow-up rate of 14%. In order to achieve this sample, one would need to identify patients from databases of GP practices with a total population of 230,000 patients, or approximately 15 GP practices roughly equal in size to the one involved in this study (i.e. 15,694 patients). Conclusion: This pilot study has allowed a number of recommendations to be made to facilitate the design of a large-scale trial, which in turn will help to clarify the existing evidence base on acupuncture for neck pain
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mHealth: providing a mindfulness app for women with chronic pelvic pain in gynaecology outpatient clinics: qualitative data analysis of user experience and lessons learnt
OBJECTIVES: To determine whether a pre-existing smartphone app to teach mindfulness meditation is acceptable to women with chronic pelvic pain (CPP) and can be integrated into clinical practice within the National Health Service (NHS) CPP pathways, and to inform the design of a potential randomised clinical trial.
DESIGN: A prestudy patient and public involvement (PPI) group to collect feedback on the acceptability of the existing app and study design was followed by a three-arm randomised feasibility trial. In addition, we undertook interviews and focus groups with patients and staff to explore app usability and acceptability. We also obtained participant comments on the research process, such as acceptability of the study questionnaires.
SETTING: Two gynaecology clinics within Barts Health NHS, London, UK.
PARTICIPANTS: Patients with CPP lasting â„6 months with access to smartphone or personal computer and understanding of basic English.
INTERVENTION: The intervention was mindfulness meditation content plus additional pain module delivered by a smartphone app. Active controls received muscle relaxation content from the same app. Passive (waiting list) controls received usual care.
MAIN OUTCOME MEASURES: Themes on user feedback, app usability and integration, and reasons for using/not using the app.
RESULTS: The use of the app was low in both active groups. Patients in the prestudy PPI group, all volunteers, were enthusiastic about the app (convenience, content, portability, flexibility, ease of use). Women contributing to the interview or focus group data (n=14), from a 'real world' clinic (some not regular app users), were less positive, citing as barriers lack of opportunities/motivation to use the app and lack of familiarity and capabilities with technology. Staff (n=7) were concerned about the potential need for extra support for them and for the patients, and considered the app needed organisational backing and peer acceptance.
CONCLUSION: The opinions of prestudy PPI volunteers meeting in their private time may not represent those of patients recruited at a routine clinic appointment. It may be more successful to codesign/codevelop an app with typical users than to adapt existing apps for use in real-world clinical populations.
TRIAL REGISTRATION NUMBER: ISRCTN10925965
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