68,667 research outputs found
Real-World Repetition Estimation by Div, Grad and Curl
We consider the problem of estimating repetition in video, such as performing
push-ups, cutting a melon or playing violin. Existing work shows good results
under the assumption of static and stationary periodicity. As realistic video
is rarely perfectly static and stationary, the often preferred Fourier-based
measurements is inapt. Instead, we adopt the wavelet transform to better handle
non-static and non-stationary video dynamics. From the flow field and its
differentials, we derive three fundamental motion types and three motion
continuities of intrinsic periodicity in 3D. On top of this, the 2D perception
of 3D periodicity considers two extreme viewpoints. What follows are 18
fundamental cases of recurrent perception in 2D. In practice, to deal with the
variety of repetitive appearance, our theory implies measuring time-varying
flow and its differentials (gradient, divergence and curl) over segmented
foreground motion. For experiments, we introduce the new QUVA Repetition
dataset, reflecting reality by including non-static and non-stationary videos.
On the task of counting repetitions in video, we obtain favorable results
compared to a deep learning alternative
Reduced Deadtime and Higher Rate Photon-Counting Detection using a Multiplexed Detector Array
We present a scheme for a photon-counting detection system that can be
operated at incident photon rates higher than otherwise possible by suppressing
the effects of detector deadtime. The method uses an array of N detectors and a
1-by-N optical switch with a control circuit to direct input light to live
detectors. Our calculations and models highlight the advantages of the
technique. In particular, using this scheme, a group of N detectors provides an
improvement in operation rate that can exceed the improvement that would be
obtained by a single detector with deadtime reduced by 1/N, even if it were
feasible to produce a single detector with such a large improvement in
deadtime. We model the system for continuous and pulsed light sources, both of
which are important for quantum metrology and quantum key distribution
applications.Comment: 6 figure
Untangling the concept of coercive control: Theorizing domestic violent crime
The paper assesses three approaches to domestic violence: two that use the concept of âcoercive controlâ and one that uses âdomestic violent crimeâ. These are: Starkâs concept of coercive control; Johnsonâs distinction between situational couple violence and intimate terrorism, in which coercive control is confined to the latter; and that of domestic violent crime, in which all physical violence is conceptualised as coercive and controlling. The paper assesses these three approaches on seven issues. It offers original analysis of data from the Crime Survey for England and Wales concerning variations in repetition and seriousness in domestic violent crime. It links escalation in domestic violent crime to variations in the economic resources of the victim. It concludes that the concept of domestic violent crime is preferable to that of coercive control when seeking to explain variations in domestic violence
Probing subtle fluorescence dynamics in cellular proteins by streak camera based Fluorescence Lifetime Imaging Microscopy
We report the cell biological applications of a recently developed
multiphoton fluorescence lifetime imaging microscopy system using a streak
camera (StreakFLIM). The system was calibrated with standard fluorophore
specimens and was shown to have high accuracy and reproducibility. We
demonstrate the applicability of this instrument in living cells for measuring
the effects of protein targeting and point mutations in the protein sequence
which are not obtainable in conventional intensity based fluorescence
microscopy methods. We discuss the relevance of such time resolved information
in quantitative energy transfer microscopy and in measurement of the parameters
characterizing intracellular physiology
Quantitative Imaging of Protein-Protein Interactions by Multiphoton Fluorescence Lifetime Imaging Microscopy using a Streak camera
Fluorescence Lifetime Imaging Microscopy (FLIM) using multiphoton excitation
techniques is now finding an important place in quantitative imaging of
protein-protein interactions and intracellular physiology. We review here the
recent developments in multiphoton FLIM methods and also present a description
of a novel multiphoton FLIM system using a streak camera that was developed in
our laboratory. We provide an example of a typical application of the system in
which we measure the fluorescence resonance energy transfer between a
donor/acceptor pair of fluorescent proteins within a cellular specimen.Comment: Overview of FLIM techniques, StreakFLIM instrument, FRET application
Remembering 'zeal' but not 'thing':reverse frequency effects as a consequence of deregulated semantic processing
More efficient processing of high frequency (HF) words is a ubiquitous finding in healthy individuals, yet frequency effects are often small or absent in stroke aphasia. We propose that some patients fail to show the expected frequency effect because processing of HF words places strong demands on semantic control and regulation processes, counteracting the usual effect. This may occur because HF words appear in a wide range of linguistic contexts, each associated with distinct semantic information. This theory predicts that in extreme circumstances, patients with impaired semantic control should show an outright reversal of the normal frequency effect. To test this prediction, we tested two patients with impaired semantic control with a delayed repetition task that emphasised activation of semantic representations. By alternating HF and low frequency (LF) trials, we demonstrated a significant repetition advantage for LF words, principally because of perseverative errors in which patients produced the previous LF response in place of the HF target. These errors indicated that HF words were more weakly activated than LF words. We suggest that when presented with no contextual information, patients generate a weak and unstable pattern of semantic activation for HF words because information relating to many possible contexts and interpretations is activated. In contrast, LF words tend are associated with more stable patterns of activation because similar semantic information is activated whenever they are encountered
Subitizing with Variational Autoencoders
Numerosity, the number of objects in a set, is a basic property of a given
visual scene. Many animals develop the perceptual ability to subitize: the
near-instantaneous identification of the numerosity in small sets of visual
items. In computer vision, it has been shown that numerosity emerges as a
statistical property in neural networks during unsupervised learning from
simple synthetic images. In this work, we focus on more complex natural images
using unsupervised hierarchical neural networks. Specifically, we show that
variational autoencoders are able to spontaneously perform subitizing after
training without supervision on a large amount images from the Salient Object
Subitizing dataset. While our method is unable to outperform supervised
convolutional networks for subitizing, we observe that the networks learn to
encode numerosity as basic visual property. Moreover, we find that the learned
representations are likely invariant to object area; an observation in
alignment with studies on biological neural networks in cognitive neuroscience
In Defense of Alain Badiou
In lieu of an abstract, here are the article\u27s first two paragraphs:
In Issue 107, Philosophy Now published James Alexanderâs âA Refutation of Snails by Roast Beef\u27, an article decrying con temporary French philosopher Alain Badiou (b.l937). Alexanderâs jumping-off point was Roger Scrutonâs unfavorable review of Badiouâs The Adventure of French Philosophy (2012). He acknowledges that Scruton âobviously dislikes everything Badiou stands forâ but takes Scruton to task for being too polite; he writes that âBadiou deserves derision.â A few sentences later, he claims that âa lot of Badiou is rubbish. There is nothing to Badiou be done with it except laugh.â Not even Badiouâs students escape Alexanderâs comments: he scoffs that instead of taking notes in Badiouâs lectures, surely the students âjust stand and cheer.â
Although I might get much enjoyment from indulging in a similarly dismissive attitude toward Alexanderâs largely ad hominem attacks against Badiou, I have chosen a different path in defending him. I honor the dialectical process of Socratesâ philosophical approach; therefore I offer a counterargument to expose the inaccuracy of Alexanderâs underestimation of Badiou. I will not advance uninformed opinions based on insufficient familiarity (Alexander confesses a lack of knowledge of Badiouâs oeuvre). Instead, I offer a perspective based on an engagement with and a deep reverence for Badiouâs philosophy
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