4,267 research outputs found
High single-mode power conversion efficiency vertical-cavity top-surface-emitting lasers
Includes bibliographical references.We report advances in the power conversion (wall-plug) efficiency of vertical-cavity top-surface-emitting lasers. The devices were fabricated from molecular beam epitaxial layers using deep proton implants to define gain-guided lasers. The epitaxial structure included low resistance, piecewise linearly graded n-type and p-type mirrors, a triple In0.2Ga0.8As quantum-well active region, and a delta-doped contact layer. Power conversion efficiencies as high as 12.7% for continuous-wave single-mode operation were measured after several hours of device operation.This work was supported by the U.S. Department of Energy under Contract DE-AC04-76DP00789
Aspirated capacitor measurements of air conductivity and ion mobility spectra
Measurements of ions in atmospheric air are used to investigate atmospheric
electricity and particulate pollution. Commonly studied ion parameters are (1)
air conductivity, related to the total ion number concentration, and (2) the
ion mobility spectrum, which varies with atmospheric composition. The physical
principles of air ion instrumentation are long-established. A recent
development is the computerised aspirated capacitor, which measures ions from
(a) the current of charged particles at a sensing electrode, and (b) the rate
of charge exchange with an electrode at a known initial potential, relaxing to
a lower potential. As the voltage decays, only ions of higher and higher
mobility are collected by the central electrode and contribute to the further
decay of the voltage. This enables extension of the classical theory to
calculate ion mobility spectra by inverting voltage decay time series. In
indoor air, ion mobility spectra determined from both the novel voltage decay
inversion, and an established voltage switching technique, were compared and
shown to be of similar shape. Air conductivities calculated by integration
were: 5.3 +- 2.5 fS/m and 2.7 +- 1.1 fS/m respectively, with conductivity
determined to be 3 fS/m by direct measurement at a constant voltage.
Applications of the new Relaxation Potential Inversion Method (RPIM) include
air ion mobility spectrum retrieval from historical data, and computation of
ion mobility spectra in planetary atmospheres.Comment: To be published in Review of Scientific Instrument
A novel 18F-labelled high affinity agent for PET imaging of the translocator protein
The translocator protein (TSPO) is an important target for imaging focal neuroinflammation in diseases such as brain cancer, stroke and neurodegeneration, but current tracers for non-invasive imaging of TSPO have important limitations. We present the synthesis and evaluation of a novel 3-fluoromethylquinoline-2-carboxamide, AB5186, which was prepared in eight steps using a one-pot two component indium(III)-catalysed reaction for the rapid and efficient assembly of the 4-phenylquinoline core. Biological assessment and the implementation of a physicochemical study showed AB5186 to have low nanomolar affinity for TSPO, as well as optimal plasma protein binding and membrane permeability properties. Generation of [18F]-AB5186 through 18F incorporation was achieved in good radiochemical yield and subsequent in vitro and ex vivo autoradiography revealed the ability of this compound to bind with specificity to TSPO in mouse glioblastoma xenografts. Initial positron emission tomography imaging of a glioma bearing mouse and a healthy baboon support the potential for [18F]-AB5186 use as a radiotracer for non-invasive TSPO imaging in vivo
Holographic Normal Ordering and Multi-particle States in the AdS/CFT Correspondence
The general correlator of composite operators of N=4 supersymmetric gauge
field theory is divergent. We introduce a means for renormalizing these
correlators by adding a boundary theory on the AdS space correcting for the
divergences. Such renormalizations are not equivalent to the standard normal
ordering of current algebras in two dimensions. The correlators contain contact
terms that contribute to the OPE; we relate them diagrammatically to
correlation functions of compound composite operators dual to multi-particle
states.Comment: 18 pages, one equation corr., further comments and refs. adde
SYSTEMS-2: a randomised phase II study of radiotherapy dose escalation for pain control in malignant pleural mesothelioma
SYSTEMS-2 is a randomised study of radiotherapy dose escalation for pain control in 112 patients with malignant pleural mesothelioma (MPM). Standard palliative (20Gy/5#) or dose escalated treatment (36Gy/6#) will be delivered using advanced radiotherapy techniques and pain responses will be compared at week 5. Data will guide optimal palliative radiotherapy in MPM
PSS32 Impact of dry eye on everyday life (Ideel) - Symptom bother: Estimating cut-off scores for dry eye severity groups
The aims of the study were to estimate score ranges associated with dry eye severity based on the Impact of Dry Eye on Everyday Life (IDEEL) Symptom Bother (SB) domain, and to evaluate the overall performance of the SB domain
Simplifying Algebra in Feynman Graphs, Part III: Massive Vectors
A T-dualized selfdual inspired formulation of massive vector fields coupled
to arbitrary matter is generated; subsequently its perturbative series modeling
a spontaneously broken gauge theory is analyzed. The new Feynman rules and
external line factors are chirally minimized in the sense that only one type of
spin index occurs in the rules. Several processes are examined in detail and
the cross-sections formulated in this approach. A double line formulation of
the Lorentz algebra for Feynman diagrams is produced in this formalism, similar
to color ordering, which follows from a spin ordering of the Feynman rules. The
new double line formalism leads to further minimization of gauge invariant
scattering in perturbation theory. The dualized electroweak model is also
generated.Comment: 39 pages, LaTeX, 8 figure
The art of being human : a project for general philosophy of science
Throughout the medieval and modern periods, in various sacred and secular guises, the unification of all forms of knowledge under the rubric of âscienceâ has been taken as the prerogative of humanity as a species. However, as our sense of species privilege has been called increasingly into question, so too has the very salience of âhumanityâ and âscienceâ as general categories, let alone ones that might bear some essential relationship to each other. After showing how the ascendant Stanford School in the philosophy of science has contributed to this joint demystification of âhumanityâ and âscienceâ, I proceed on a more positive note to a conceptual framework for making sense of science as the art of being human. My understanding of âscienceâ is indebted to the red thread that runs from Christian theology through the Scientific Revolution and Enlightenment to the Humboldtian revival of the university as the site for the synthesis of knowledge as the culmination of self-development. Especially salient to this idea is scienceâs epistemic capacity to manage modality (i.e. to determine the conditions under which possibilities can be actualised) and its political capacity to organize humanity into projects of universal concern. However, the challenge facing such an ideal in the twentyfirst century is that the predicate âhumanâ may be projected in three quite distinct ways, governed by what I call âecologicalâ, âbiomedicalâ and âcyberneticâ interests. Which one of these future humanities would claim todayâs humans as proper ancestors and could these futures co-habit the same world thus become two important questions that general philosophy of science will need to address in the coming years
Establishing the values for patient engagement (PE) in health-related quality of life (HRQoL) research: an international, multiple-stakeholder perspective
PurposeActive patient engagement is increasingly viewed as essential to ensuring that patient-driven perspectives are considered throughout the research process. However, guidance for patient engagement (PE) in HRQoL research does not exist, the evidence-base for practice is limited, and we know relatively little about underpinning values that can impact on PE practice. This is the first study to explore the values that should underpin PE in contemporary HRQoL research to help inform future good practice guidance. MethodsA modified âWorld CafĂ©â was hosted as a collaborative activity between patient partners, clinicians and researchers: self-nominated conference delegates participated in group discussions to explore values associated with the conduct and consequences of PE. Values were captured via post-it notes and by nominated note-takers. Data were thematically analysed: emergent themes were coded and agreement checked. Association between emergent themes, values and the Public Involvement Impact Assessment Framework were explored. ResultsEighty participants, including 12 patient partners, participated in the 90-min event. Three core values were defined: (1) building relationships; (2) improving research quality and impact; and (3) developing best practice. Participants valued the importance of building genuine, collaborative and deliberative relationshipsâunderpinned by honesty, respect, co-learning and equityâand the impact of effective PE on research quality and relevance. Conclusions An explicit statement of values seeks to align all stakeholders on the purpose, practice and credibility of PE activities. An innovative, flexible and transparent research environment was valued as essential to developing a trustworthy evidence-base with which to underpin future guidance for good PE practice.Peer reviewe
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