VLF Tests Conducted by NEETRAC as Part of the CDFI

Presented at the Fall 2007 PES-ICC meeting.This material is based upon work supported by the Department of Energy under Award No DE-FC02-04CH1237 and CDFI

Mice produce ultrasonic vocalizations by intra-laryngeal planar impinging jets

Rodent ultrasonic vocalizations (USVs) are a vital tool for linking gene mutations to behavior in mouse models of communication disorders, such as autism [1. However, we currently lack an understanding of how physiological and physical mechanisms combine to generate acoustic features of the vocalizations, and thus cannot meaningfully relate those features to experimental treatments. Here we test and provide evidence against the two leading hypotheses explaining USV production: superficial vocal fold vibrations [2, and a hole-tone whistle [3. Instead, we propose and provide theoretical and experimental evidence for an alternative and novel vocal production mechanism: a glottal jet impinging onto the laryngeal inner planar wall. Our data provide a framework for future research on the neuromuscular control of mouse vocal production and for interpreting mouse vocal behavior phenotypes.National Science Foundation (Grant ID: IOS 1257768), Danish Research Council, Carlsberg Foundatio

Review Article: Medical management of opioid dependence in South Africa

Medical practitioners in South Africa are increasingly confronted with requests to treat patients with opioid use disorders. Many do not possess the required knowledge and skills to deal with these patients effectively. This overview of the medical treatment of opioid dependence was compiled by an elected working group of doctors working in the field of substance dependence. Recommendations are based on current best practice derived from scientific evidence and consensus of the working group, but should never replace individual clinical judgement.South African Medical Journal Vol. 98 (4) 2008: pp. 280-28

Withstand Tests: More Than Meets the Eye

Presented at the Insulated Conductors Committee, San Antonio, Texas, October 26-29, 2008.This material is based upon work supported by the Department of Energy under Award No DE-FC02-04CH1237 and CDFI

Frequency decoding of periodically timed action potentials through distinct activity patterns in a random neural network

Frequency discrimination is a fundamental task of the auditory system. The mammalian inner ear, or cochlea, provides a place code in which different frequencies are detected at different spatial locations. However, a temporal code based on spike timing is also available: action potentials evoked in an auditory-nerve fiber by a low-frequency tone occur at a preferred phase of the stimulus-they exhibit phase locking-and thus provide temporal information about the tone's frequency. In an accompanying psychoacoustic study, and in agreement with previous experiments, we show that humans employ this temporal information for discrimination of low frequencies. How might such temporal information be read out in the brain? Here we demonstrate that recurrent random neural networks in which connections between neurons introduce characteristic time delays, and in which neurons require temporally coinciding inputs for spike initiation, can perform sharp frequency discrimination when stimulated with phase-locked inputs. Although the frequency resolution achieved by such networks is limited by the noise in phase locking, the resolution for realistic values reaches the tiny frequency difference of 0.2% that has been measured in humans.Comment: 16 pages, 5 figures, and supplementary informatio

Incremental Mutual Information: A New Method for Characterizing the Strength and Dynamics of Connections in Neuronal Circuits

Understanding the computations performed by neuronal circuits requires characterizing the strength and dynamics of the connections between individual neurons. This characterization is typically achieved by measuring the correlation in the activity of two neurons. We have developed a new measure for studying connectivity in neuronal circuits based on information theory, the incremental mutual information (IMI). By conditioning out the temporal dependencies in the responses of individual neurons before measuring the dependency between them, IMI improves on standard correlation-based measures in several important ways: 1) it has the potential to disambiguate statistical dependencies that reflect the connection between neurons from those caused by other sources (e. g. shared inputs or intrinsic cellular or network mechanisms) provided that the dependencies have appropriate timescales, 2) for the study of early sensory systems, it does not require responses to repeated trials of identical stimulation, and 3) it does not assume that the connection between neurons is linear. We describe the theory and implementation of IMI in detail and demonstrate its utility on experimental recordings from the primate visual system

Transfer RNA-derived small RNAs in the cancer transcriptome

The cellular lifetime includes stages such as differentiation, proliferation, division, senescence and apoptosis.These stages are driven by a strictly ordered process of transcription dynamics. Molecular disruption to RNA polymerase assembly, chromatin remodelling and transcription factor binding through to RNA editing, splicing, post-transcriptional regulation and ribosome scanning can result in significant costs arising from genome instability. Cancer development is one example of when such disruption takes place. RNA silencing is a term used to describe the effects of post-transcriptional gene silencing mediated by a diverse set of small RNA molecules. Small RNAs are crucial for regulating gene expression and microguarding genome integrity.RNA silencing studies predominantly focus on small RNAs such as microRNAs, short-interfering RNAs and piwi-interacting RNAs. We describe an emerging renewal of inter-est in a‘larger’small RNA, the transfer RNA (tRNA).Precisely generated tRNA-derived small RNAs, named tRNA halves (tiRNAs) and tRNA fragments (tRFs), have been reported to be abundant with dysregulation associated with cancer. Transfection of tiRNAs inhibits protein translation by displacing eukaryotic initiation factors from messenger RNA (mRNA) and inaugurating stress granule formation.Knockdown of an overexpressed tRF inhibits cancer cell proliferation. Recovery of lacking tRFs prevents cancer metastasis. The dual oncogenic and tumour-suppressive role is typical of functional small RNAs. We review recent reports on tiRNA and tRF discovery and biogenesis, identification and analysis from next-generation sequencing data and a mechanistic animal study to demonstrate their physiological role in cancer biology. We propose tRNA-derived small RNA-mediated RNA silencing is an innate defence mechanism to prevent oncogenic translation. We expect that cancer cells are percipient to their ablated control of transcription and attempt to prevent loss of genome control through RNA silencing

An associative memory of Hodgkin-Huxley neuron networks with Willshaw-type synaptic couplings

An associative memory has been discussed of neural networks consisting of spiking N (=100) Hodgkin-Huxley (HH) neurons with time-delayed couplings, which memorize P patterns in their synaptic weights. In addition to excitatory synapses whose strengths are modified after the Willshaw-type learning rule with the 0/1 code for quiescent/active states, the network includes uniform inhibitory synapses which are introduced to reduce cross-talk noises. Our simulations of the HH neuron network for the noise-free state have shown to yield a fairly good performance with the storage capacity of $\alpha_c = P_{\rm max}/N \sim 0.4 - 2.4$ for the low neuron activity of $f \sim 0.04-0.10$. This storage capacity of our temporal-code network is comparable to that of the rate-code model with the Willshaw-type synapses. Our HH neuron network is realized not to be vulnerable to the distribution of time delays in couplings. The variability of interspace interval (ISI) of output spike trains in the process of retrieving stored patterns is also discussed.Comment: 15 pages, 3 figures, changed Titl

‘Our newsroom in the cloud’: Slack, virtual newsrooms and journalistic practice

Virtual newsrooms have enormous potential: enabling journalists around the world to pool their knowledge, skills and perspectives within joint projects, such as the Panama Papers. These virtual newsrooms are supported by Online Collaborative Software (OCS), the most popular of which is Slack. But although many of the world’s top news organisations now use Slack, there is no empirical research examining its impact on workplace processes or culture. This article presents the results of a year-long ethnographic study of a global digital news outlet, whose remote journalists collaborate, almost exclusively, via Slack. We found that the platform deepened relationships and enabled new creative practices across geographic regions. However, it also contributed to the erasure of the line between private and professional spheres for workers, and introduced new opportunities for management to shape newsroom culture. We argue that the concept of ‘space’ as developed by Harvey can helpfully frame the analysis of these new, important digital platforms

Hanging Out, Messing Around, and Geeking Out

The tenth-anniversary edition of a foundational text in digital media and learning, examining new media practices that range from podcasting to online romantic breakups. Hanging Out, Messing Around, and Geeking Out, first published in 2009, has become a foundational text in the field of digital media and learning. Reporting on an ambitious three-year ethnographic investigation into how young people live and learn with new media in varied settings—at home, in after-school programs, and in online spaces—it presents a flexible and useful framework for understanding the ways that young people engage with and through online platforms: hanging out, messing around, and geeking out, otherwise known as HOMAGO. Integrating twenty-three case studies—which include Harry Potter podcasting, video-game playing, music sharing, and online romantic breakups—in a unique collaborative authorship style, Hanging Out, Messing Around, and Geeking Out combines in-depth descriptions of specific group dynamics with conceptual analysis. Since its original publication, digital learning labs in libraries and museums around the country have been designed around the HOMAGO mode and educators have created HOMAGO guidebooks and toolkits. This tenth-anniversary edition features a new introduction by Mizuko Ito and Heather Horst that discusses how digital youth culture evolved in the intervening decade, and looks at how HOMAGO has been put into practice. This book was written as a collaborative effort by members of the Digital Youth Project, a three-year research effort funded by the John D. and Catherine T. MacArthur Foundation and conducted at the University of California, Berkeley, and the University of Southern California