2,799 research outputs found
Computational convergence of the path integral for real dendritic morphologies
Neurons are characterised by a morphological structure unique amongst biological cells, the core of which is the dendritic tree. The vast number of dendritic geometries, combined with heterogeneous properties of the cell membrane, continue to challenge scientists in predicting neuronal input-output relationships, even in the case of sub-threshold dendritic currents. The Green’s function obtained for a given dendritic geometry provides this functional relationship for passive or quasi-active dendrites and can be constructed by a sum-over-trips approach based on a path integral formalism. In this paper, we introduce a number of efficient algorithms for realisation of the sum-over-trips framework and investigate the convergence of these algorithms on different dendritic geometries. We demonstrate that the convergence of the trip sampling methods strongly depends on dendritic morphology as well as the biophysical properties of the cell membrane. For real morphologies, the number of trips to guarantee a small convergence error might become very large and strongly affect computational efficiency. As an alternative, we introduce a highly-efficient matrix method which can be applied to arbitrary branching structures
Rethinking Science Literacy in the Face of Anthropogenic Climate Change: The Power of Productive Skepticism
Senior Project submitted to The Division of Social Studies of Bard College
Strong quantum correlations in four wave mixing in Rb vapor
We study quantum intensity correlations produced using four-wave mixing in a
room-temperature rubidium vapor cell. An extensive study of the effect of the
various parameters allows us to observe very large amounts of non classical
correlations.Comment: 8 pages and 8 figures; work presented at the SPIE Photonics Europe
conference (Brussels, 2010
MPAgenomics : An R package for multi-patients analysis of genomic markers
MPAgenomics, standing for multi-patients analysis (MPA) of genomic markers,
is an R-package devoted to: (i) efficient segmentation, and (ii) genomic marker
selection from multi-patient copy number and SNP data profiles. It provides
wrappers from commonly used packages to facilitate their repeated (sometimes
difficult) use, offering an easy-to-use pipeline for beginners in R. The
segmentation of successive multiple profiles (finding losses and gains) is
based on a new automatic choice of influential parameters since default ones
were misleading in the original packages. Considering multiple profiles in the
same time, MPAgenomics wraps efficient penalized regression methods to select
relevant markers associated with a given response
The role of electron polarization on nuclear spin diffusion
Dynamic nuclear polarization (DNP) is capable of boosting signals in nuclear
magnetic resonance by orders of magnitude by creating out-of-equilibrium
nuclear spin polarization. The diffusion of nuclear spin polarization in the
vicinity of paramagnetic dopants is a crucial step for DNP and remains yet not
well understood. In this Letter, we show that the polarization of the electron
spin controls the rate of proton spin diffusion in a DNP sample at 1.2 K and 7
T; at increasingly high electron polarization, spin diffusion vanishes. We
rationalize our results using a 2 nucleus - 1 electron model and Lindblad s
Master equation, which generalizes preexisting models in the literature and
qualitatively accounts for the experimental observed spin diffusion dynamics.Comment: Main text: 6 pages, 3 figures Supplement: 9 pages, 4 figure
Risk and Measures of Rural Poverty in Burkina Faso
This article assesses the importance of risk in the measurement of rural poverty in Burkina Faso. The analysis is based on longitudinal data collected as part of monitoring and evaluation activities for the PNGT-2 project on community development in the country. The first part of the study is devoted to traditional estimates of poverty for the period 2004 to 2006 and an analysis of movements in and out of poverty between the various survey years. The second part of the study shows how the integration of risk into the measurement of poverty tends to increase these measures significantly.Rural poverty; risk; income stabilization; Burkina Faso
Strata of k-differentials
A k-differential on a Riemann surface is a section of the kth power of the canonical line bundle. Loci of k-differentials with prescribed number and multiplicities of zeros and poles form a natural stratification of the moduli space of k-differentials. In this paper, we give a complete description for the compactification of the strata of k-differentials in terms of pointed stable k-differentials, for all k. The upshot is a global k-residue condition that can also be reformulated in terms of admissible covers of stable curves. Moreover, we study properties of k-differentials regarding their deformations, residues, and at geometric structure
Harnessing AI for Speech Reconstruction using Multi-view Silent Video Feed
Speechreading or lipreading is the technique of understanding and getting
phonetic features from a speaker's visual features such as movement of lips,
face, teeth and tongue. It has a wide range of multimedia applications such as
in surveillance, Internet telephony, and as an aid to a person with hearing
impairments. However, most of the work in speechreading has been limited to
text generation from silent videos. Recently, research has started venturing
into generating (audio) speech from silent video sequences but there have been
no developments thus far in dealing with divergent views and poses of a
speaker. Thus although, we have multiple camera feeds for the speech of a user,
but we have failed in using these multiple video feeds for dealing with the
different poses. To this end, this paper presents the world's first ever
multi-view speech reading and reconstruction system. This work encompasses the
boundaries of multimedia research by putting forth a model which leverages
silent video feeds from multiple cameras recording the same subject to generate
intelligent speech for a speaker. Initial results confirm the usefulness of
exploiting multiple camera views in building an efficient speech reading and
reconstruction system. It further shows the optimal placement of cameras which
would lead to the maximum intelligibility of speech. Next, it lays out various
innovative applications for the proposed system focusing on its potential
prodigious impact in not just security arena but in many other multimedia
analytics problems.Comment: 2018 ACM Multimedia Conference (MM '18), October 22--26, 2018, Seoul,
Republic of Kore
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