10,936 research outputs found
In vivo laser Doppler holography of the human retina
The eye offers a unique opportunity for non-invasive exploration of
cardiovascular diseases. Optical angiography in the retina requires sensitive
measurements, which hinders conventional full-field laser Doppler imaging
schemes. To overcome this limitation, we used digital holography to perform
laser Doppler perfusion imaging of the human retina in vivo with near-infrared
light. Wideband measurements of the beat frequency spectrum of optical
interferograms recorded with a 39 kHz CMOS camera are analyzed by short-time
Fourier transformation. Power Doppler images and movies drawn from the zeroth
moment of the power spectrum density reveal blood flows in retinal and
choroidal vessels over 512 512 pixels covering 2.4 2.4 mm
on the retina with a 13 ms temporal resolution.Comment: 5 pages, 5 figure
Data compression and regression based on local principal curves.
Frequently the predictor space of a multivariate regression problem of the type y = m(x_1, …, x_p ) + ε is intrinsically one-dimensional, or at least of far lower dimension than p. Usual modeling attempts such as the additive model y = m_1(x_1) + … + m_p (x_p ) + ε, which try to reduce the complexity of the regression problem by making additional structural assumptions, are then inefficient as they ignore the inherent structure of the predictor space and involve complicated model and variable selection stages. In a fundamentally different approach, one may consider first approximating the predictor space by a (usually nonlinear) curve passing through it, and then regressing the response only against the one-dimensional projections onto this curve. This entails the reduction from a p- to a one-dimensional regression problem.
As a tool for the compression of the predictor space we apply local principal curves. Taking things on from the results presented in Einbeck et al. (Classification – The Ubiquitous Challenge. Springer, Heidelberg, 2005, pp. 256–263), we show how local principal curves can be parametrized and how the projections are obtained. The regression step can then be carried out using any nonparametric smoother. We illustrate the technique using data from the physical sciences
Designing Courses for Significant Learning: Voices of Experience: New Directions for Teaching and Learning, no. 119
Marice Rose and Roben Torosyan are contributing authors, Integrating Big Questions with Real World Applications: Models from Art History and Philosophy , p. 61-71.
Book Description: Leading researchers and practitioners explore the frontiers of education from an Integral perspective.The educational challenges faced today are driving us toward a new step in the evolution of educational theory and practice. Educators are called to go beyond simply presenting alternatives, to integrating the best of mainstream and alternative approaches and taking them to the next level. Integral Education accomplishes this by bringing together leading researchers and practitioners from higher education who are actively exploring the frontiers of education from an integral perspective. It presents an overview of the emerging landscape of integral education from a variety of theoretical and applied perspectives. Key characteristics of integral education include exploring multiple perspectives, employing different pedagogical techniques (e.g., reflective, dialogical, empirical), combining conceptual rigor with embodied experience, drawing on developmental psychology, and cultivating a reflective and transformative space for students and teachers alike. Integral Education provides the most comprehensive synopsis of this exciting new approach and serves as a valuable resource for any integral effort within education. - Publisher descriptionhttps://digitalcommons.fairfield.edu/visualandperformingarts-books/1000/thumbnail.jp
Building faculty capacity for better teaching and learning
Enhancing faculty capacity for teaching in ways that promote greater levels of student engagement and significant learning is an essential part of all other institutional changes designed to advance higher quality student learning. In this session, participants will lay out a general strategy for campus leaders to cultivate that faculty capability and then identify specific actions needed to implement such a strategy. Participants will also identify key elements of effective teaching and learning centers and brainstorm ways to build a teaching- and learning-centered institutional culture
Pulsatile microvascular blood flow imaging by short-time Fourier transform analysis of ultrafast laser holographic interferometry
We report on wide-field imaging of pulsatile microvascular blood flow in the
exposed cerebral cortex of a mouse by holographic interferometry. We recorded
interferograms of laser light backscattered by the tissue, beating against an
off-axis reference beam with a 50 kHz framerate camera. Videos of local Doppler
contrasts were rendered numerically by Fresnel transformation and short-time
Fourier transform analysis. This approach enabled instantaneous imaging of
pulsatile blood flow contrasts in superficial blood vessels over 256 x 256
pixels with a spatial resolution of 10 microns and a temporal resolution of 20
ms.Comment: 4 page
Geometric Phase and Non-Adiabatic Effects in an Electronic Harmonic Oscillator
Steering a quantum harmonic oscillator state along cyclic trajectories leads
to a path-dependent geometric phase. Here we describe an experiment observing
this geometric phase in an electronic harmonic oscillator. We use a
superconducting qubit as a non-linear probe of the phase, otherwise
unobservable due to the linearity of the oscillator. Our results demonstrate
that the geometric phase is, for a variety of cyclic trajectories, proportional
to the area enclosed in the quadrature plane. At the transition to the
non-adiabatic regime, we study corrections to the phase and dephasing of the
qubit caused by qubit-resonator entanglement. The demonstrated controllability
makes our system a versatile tool to study adiabatic and non-adiabatic
geometric phases in open quantum systems and to investigate the potential of
geometric gates for quantum information processing
Universal Tutte characters via combinatorial coalgebras
The Tutte polynomial is the most general invariant of matroids and graphs
that can be computed recursively by deleting and contracting edges. We
generalize this invariant to any class of combinatorial objects with deletion
and contraction operations, associating to each such class a universal Tutte
character by a functorial procedure. We show that these invariants satisfy a
universal property and convolution formulae similar to the Tutte polynomial.
With this machinery we recover classical invariants for delta-matroids, matroid
perspectives, relative and colored matroids, generalized permutohedra, and
arithmetic matroids, and produce some new convolution formulae. Our principal
tools are combinatorial coalgebras and their convolution algebras. Our results
generalize in an intrinsic way the recent results of
Krajewski--Moffatt--Tanasa.Comment: Accepted version, 51p
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