43,060 research outputs found
Detectability index measures of binaural masking level difference across populations of inferior colliculus neurons.
In everyday life we continually need to detect signals against a background of interfering noise (the “cocktail party effect”): a task that is much easier to accomplish using two ears. The binaural masking level difference (BMLD) measures the ability of listeners to use a difference in binaural attributes to segregate sound sources and thus improve their discriminability against interfering noises. By computing the detectability of tones from rate-versus-level functions in the presence of a suprathreshold noise, we previously demonstrated that individual low-frequency delay-sensitive neurons in the inferior colliculus are able to show BMLDs. Here we consider the responses of a population of such neurons when the noise level is held constant (as conventionally in psychophysical paradigms). We have sampled the responses of 121 units in the inferior colliculi of five guinea pigs to identical noise and 500 Hz tones at both ears (NoSo) and to identical noise but with the 500 Hz tone at one ear inverted (NoSπ). The result suggests that the neurons subserving detection of So tones in No (identical noise at the two ears) noise are those neurons with best frequencies (BFs) close to 500 Hz that respond to So tones with an increase in their discharge rate from that attributable to the noise. The detection of the inverted (Sπ) signal is also attributable to neurons with BFs close to 500 Hz. However, among these neurons, the presence of the Sπ tone was indicated by an increased discharge rate in some neurons and by a decreased discharge rate in others
Big hART at John Northcott Estate: Community, Health and the Arts
This paper considers the work of Big hART, a social impact of the Arts company, in their residency entitled Northcott Narratives over three and half years at John Northcott Estate, a public housing estate in Sydney. During this time Big hART used arts practice to engage tenants, strengthen their creative dispositions, and build relationships between tenants and a range of different communities. Northcott Narratives used a variety of multi-modal forms with tenants to inquire into, and then express ideas in relation to issues that confront them. These ideas are presented as social policy recommendations. The power and benefits of this form of arts practice along with the tensions and challenges are revealed. The paper adds to the developing discourse in relation to community cultural development
Spring separation of spacecraft
IBM 7090 digital computer program for solving equations of motion for spacecraft separating from final rocket stage or another spacecraft by means of precision helical compression spring
Convergent input from brainstem coincidence detectors onto delay-sensitive neurons in the inferior colliculus.
Responses of low-frequency neurons in the inferior colliculus (IC) of anesthetized guinea pigs were studied with binaural beats to assess their mean best interaural phase (BP) to a range of stimulating frequencies. Phase plots (stimulating frequency vs BP) were produced, from which measures of characteristic delay (CD) and characteristic phase (CP) for each neuron were obtained. The CD provides an estimate of the difference in travel time from each ear to coincidence-detector neurons in the brainstem. The CP indicates the mechanism underpinning the coincidence detector responses. A linear phase plot indicates a single, constant delay between the coincidencedetector inputs from the two ears. In more than half (54 of 90) of the neurons, the phase plot was not linear. We hypothesized that neurons with nonlinear phase plots received convergent input from brainstem coincidence detectors with different CDs.
Presentation of a second tone with a fixed, unfavorable delay suppressed the response of one input, linearizing the phase plot and revealing other inputs to be relatively simple coincidence detectors. For some neurons with highly complex phase plots, the suppressor tone altered BP values, but did not resolve the nature of the inputs. For neurons with linear phase plots, the suppressor tone either completely abolished their responses or reduced their discharge rate with no change in BP.
By selectively suppressing inputs with a second tone, we are
able to reveal the nature of underlying binaural inputs to IC neurons, confirming the hypothesis that the complex phase
plots of many IC neurons are a result of convergence from
simple brainstem coincidence detectors
Experimental demonstration of a Rydberg-atom beam splitter
Inhomogeneous electric fields generated above two-dimensional electrode
structures have been used to transversely split beams of helium Rydberg atoms
into pairs of spatially separated components. The atomic beams had initial
longitudinal speeds of between 1700 and 2000 m/s and were prepared in Rydberg
states with principle quantum number and electric dipole moments of up
to 8700 D by resonance-enhanced two-color two-photon laser excitation from the
metastable 1s2s S level. Upon exiting the beam splitter the ensembles
of Rydberg atoms were separated by up to 15.6 mm and were detected by pulsed
electric field ionization. Effects of amplitude modulation of the electric
fields of the beam splitter were shown to cause particle losses through
transitions into unconfined Rydberg-Stark states.Comment: 6 pages, 5 figure
High field fractional quantum Hall effect in optical lattices
We consider interacting bosonic atoms in an optical lattice subject to a
large simulated magnetic field. We develop a model similar to a bilayer
fractional quantum Hall system valid near simple rational numbers of magnetic
flux quanta per lattice cell. Then we calculate its ground state, magnetic
lengths, fractional fillings, and find unexpected sign changes in the Hall
current. Finally we study methods for detecting these novel features via shot
noise and Hall current measurements.Comment: 4 pages, 4 figures, accepted by PR
Adaptive Sentence Boundary Disambiguation
Labeling of sentence boundaries is a necessary prerequisite for many natural
language processing tasks, including part-of-speech tagging and sentence
alignment. End-of-sentence punctuation marks are ambiguous; to disambiguate
them most systems use brittle, special-purpose regular expression grammars and
exception rules. As an alternative, we have developed an efficient, trainable
algorithm that uses a lexicon with part-of-speech probabilities and a
feed-forward neural network. After training for less than one minute, the
method correctly labels over 98.5\% of sentence boundaries in a corpus of over
27,000 sentence-boundary marks. We show the method to be efficient and easily
adaptable to different text genres, including single-case texts.Comment: This is a Latex version of the previously submitted ps file
(formatted as a uuencoded gz-compressed .tar file created by csh script). The
software from the work described in this paper is available by contacting
[email protected]
A simultaneous spin/eject mechanism for aerospace payloads
A simultaneous spin/eject mechanism was developed for aerospace applications requiring a compact, passive device which would accommodate payload support and controlled-release functions, and which would provide a highly accurate spin-ejection motion to the payload. The mechanism satisfied the requirements and is adaptable to other deployment applications
Locating and mitigating risks to children associated with major sporting events
Despite recent efforts to blend sport and human rights, activism for children's rights in sport has historically been marginalised. The positive 'social legacy' of sport events frequently masks more problematic issues, including child exploitation. We argue that harms to children in hosting communities of major sporting events (MSEs) should be a focus for both research and intervention since the plight of such children is currently a political blind spot. The article examines the evidence for four major sources of risk for children associated with such events: child labour, displacement resulting from forced evictions for infrastructure development and street clearance, child sexual exploitation, and human trafficking affecting children. The weakness of the resulting evidence is explained in relation to the methodological and ethical difficulties of conducting research on such hidden and marginal populations and to the fact that risks to children are often masked by adult social problems. It is argued that much more robust research designs, focused specifically on children, are essential in order to verify the many assertions made about risks to children associated with MSEs. Some mitigating interventions are briefly examined and an action plan for risk-mitigation work at future MSEs is proposed. Finally, drawing on wider debates about Centres and Peripheries in social and economic theory, we question whether major international sport organisations might choose to engage with projects like child protection for strategic rather than humanitarian reasons, using them as a kind of ethical fig leaf in order to bolster their power bases against threats from the margins. © 2014 © 2014 Taylor & Francis.The Oak Foundation under Grant code OCAY-13-052
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