1,111 research outputs found
Phase control and measurement in digital microscopy
The ongoing merger of the digital and optical components of the modern microscope is creating opportunities for new measurement techniques, along with new challenges for optical modelling. This thesis investigates several such opportunities and challenges which are particularly relevant to biomedical imaging. Fourier optics is used throughout the thesis as the underlying conceptual model, with a particular emphasis on three--dimensional Fourier optics. A new challenge for optical modelling provided by digital microscopy is the relaxation of traditional symmetry constraints on optical design. An extension of optical transfer function theory to deal with arbitrary lens pupil functions is presented in this thesis. This is used to chart the 3D vectorial structure of the spatial frequency spectrum of the intensity in the focal region of a high aperture lens when illuminated by linearly polarised beam. Wavefront coding has been used successfully in paraxial imaging systems to extend the depth of field. This is achieved by controlling the pupil phase with a cubic phase mask, and thereby balancing optical behaviour with digital processing. In this thesis I present a high aperture vectorial model for focusing with a cubic phase mask, and compare it with results calculated using the paraxial approximation. The effect of a refractive index change is also explored. High aperture measurements of the point spread function are reported, along with experimental confirmation of high aperture extended depth of field imaging of a biological specimen. Differential interference contrast is a popular method for imaging phase changes in otherwise transparent biological specimens. In this thesis I report on a new isotropic algorithm for retrieving the phase from differential interference contrast images of the phase gradient, using phase shifting, two directions of shear, and non--iterative Fourier phase integration incorporating a modified spiral phase transform. This method does not assume that the specimen has a constant amplitude. A simulation is presented which demonstrates good agreement between the retrieved phase and the phase of the simulated object, with excellent immunity to imaging noise
Transverse mass and invariant mass observables for measuring the mass of a semi-invisibly decaying heavy particle
Formulae are derived for the positions of end-points in the invariant mass
and transverse mass distributions obtained from the products of heavy states
decaying to pairs of semi-invisibly decaying lighter states. Formulae are
derived both for the special case where the two decay chains are identical and
the more general case where they are different. The formulae are tested with a
simple case study of heavy SUSY higgs particles decaying to gauginos at the
LHC.Comment: 13 pages, 8 eps figure
略论《共产党宣言》中的马克思主义自由观
本文着眼于《共产党宣言》中若干与马克思主义自由观有关的论述,从马克思主义自由观的历史发展,信仰自由、宗教自由、政治自由等精神领域的自由、无产阶级争取自由的斗争,以及社会自由与个人自由的发展的关系等角度进行了一些探讨,并简要分析了个人自由的发展与社会自由的发展之间的关系的现实意义
The Analysis of Multijet Events Produced at High Energy Hadron Colliders
We define and discuss a set of (4N - 4) parameters that can be used to
analyse events in which N jets have been produced in high energy hadron-hadron
collisions. These multijet variables are the multijet mass and (4N - 5)
independent dimensionless parameters. To illustrate the use of the variables
QCD predictions are presented for events with up to five jets produced at the
Fermilab Tevatron Proton-Antiproton Collider. These QCD predictions are
compared with the predictions of a model in which multijet events uniformly
populate the N-body phase-space
Prevention is better than cure: why early interventions for insomnia and chronic pain during adolescence should be a priority
Speaking of silence : myth and history in contemporary Irish women's poetry (1989-2004).
Although, Nuala Ni Dhomhnaill, Eavan Boland and Medbh McGuckian avoid
labelling themselves 'feminist poets', each provides a 'feminist insight' into what
Catriona Clutterbuck describes as their 'marginalization from official systems of
representation,.J This thesis will primarily discuss how each of these women
poets, from both the North and South of Ireland, writes from the margins of Irish
myth and history to question the concept of silence. The introduction interrogates
the meaning of silence in relation to wider philosophic responses to the politics of
silence in contemporary Irish poetry. This chapter will also briefly review some of
the more monumental anthologies of Irish literature and major works of litelary
criticism (1989-2004) to illustrate how women poets have emerged from their
obscurity and established themselves as prominent figures within a patriarchal
tradition that had previously marginalized their voices.
As an example of their rise in status, Chapter II will have a comparative
look at how all three poets employ the body to paradoxically speak of women's
silence, while using it to maintain a level of silence. This thesis will then move on
to discuss how Ni Dhomhnaill, Boland and McGuckian all write from the margins
of Irish myth and history to speak of the unspeakable. In Chapter III, Ni
Dhomhnaill speaks of women's silence through Irish myth and history by
engaging in the oral tradition of storytelling. Whereas Ni Dhomhnaill favours
myth over history, Boland's overall ambition in Chapter IV is to write woman out
of her silence, thus 'out of myth [and] into history' by using her autobiography The fifth chapter will return to the mythical realms of McGuckian' s more radical
approach to history in her later poems from Captain Lavender (1994) and discuss
her private symbolic re-reading of Northern Ireland's political history. Since in
much of their later poetry, Ni Dhomhnaill, Boland and McGuckian all adopt the
ethical position of speaking while maintaining a certain silence, Chapter VI will
conclude with a comparative look at some of the Irish women poets writing of
silence in the twenty-first century
A Unique Tryptophan C‐Prenyltransferase from the Kawaguchipeptin Biosynthetic Pathway
Acknowledgements This work was supported by funding of the Academy of Finland (259505), Helsinki University Research grant (490085) and ESCMID grant (4720572) to D.P.F., University of Pittsburgh Central Research Development Fund to X.L., Technology Strategy Board grant (131181) to W.H., M.J. and J.H.N. National Programme of Sustainability I of the Ministry of Education of the Czech Republic I grant (LO1416) to T.G.Peer reviewedPostprin
Jet measurements in the ALICE experiment at the LHC
Jet tomography probes provide a means to explore the properties of highly
compressed and excited nuclear matter created in heavy ion collisions. The
capabilities of the ALICE experiment, with its electromagnetic calorimeter
(EMCal) upgrade, to trigger on and reconstruct jets in p+p and Pb+Pb collisions
at =5.5 TeV are presented.Comment: 8 pages, 6 figures. Presented at the IX International Conference on
Nucleus-Nucleus Collisions, Rio de Janeiro, Brazil, August 28 - September 1,
200
Sqrt{shat}_{min} resurrected
We discuss the use of the variable sqrt{shat}_{min}, which has been proposed
in order to measure the hard scale of a multi parton final state event using
inclusive quantities only, on a SUSY data sample for a 14 TeV LHC. In its
original version, where this variable was proposed on calorimeter level, the
direct correlation to the hard scattering scale does not survive when effects
from soft physics are taken into account. We here show that when using
reconstructed objects instead of calorimeter energy and momenta as input, we
manage to actually recover this correlation for the parameter point considered
here. We furthermore discuss the effect of including W + jets and t tbar+jets
background in our analysis and the use of sqrt{shat}_{min} for the suppression
of SM induced background in new physics searches.Comment: 23 pages, 9 figures; v2: 1 figure, several subsections and references
as well as new author affiliation added. Corresponds to published versio
Comparison of Three-jet Events in Proton-Antiproton Collisions at sqrt{s}=1.8 TeV to Predictions from a Next-to-leading Order QCD Calculation
The properties of three-jet events with total transverse energy greater than
320 GeV and individual jet energy greater than 20 GeV have been analyzed and
compared to absolute predictions from a next-to-leading order (NLO)
perturbative QCD calculation. These data, of integrated luminosity 86 pb^-1,
were recorded by the CDF Experiment for proton-antiproton collisions at
sqrt{s}=1.8 TeV. This study tests a model of higher order QCD processes that
result in gluon emission and can be used to estimate the magnitude of the
contribution of processes higher than NLO. The total cross section is measured
to be 466 \pm 3(stat.)^{+207}_{-70}(syst.) pb. The differential cross section
is furthermore measured for all kinematically accessible regions of the Dalitz
plane, including those for which the theoretical prediction is unreliable.
While the measured cross section is consistent with the theoretical prediction
in magnitude, the two differ somewhat in shape in the Dalitz plane.Comment: For the CDF Collaboration. Contributed to the proceedings of the
Eleventh High-Energy Physics International Conference on QCD, Montpellier,
France, July 200
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