The instability of a viscous sheet floating on an air cushion

The dynamics of a thin sheet of viscous liquid levitating on an air cushion is studied. Experimentally, it is observed that, after an initial settling stage, a local disturbance grows, eventually leading to the sheet blowing up like a viscous balloon. We derive a dynamical model for the levitating sheet and propose a mechanism for the onset of the instability. This instability is driven by the local drainage of the sheet due to a growing disturbance on its lower surface and is moderated by surface tension, the bending stiffness of the sheet and advection in the air layer. The balance between these effects determines the most unstable wavelength and this is illustrated by some numerical simulations

The real time mass evaluation system as a tool for detection of undeclared cascade operation at GCEPs

Given the flexibility of current cascade designs a real time mass monitoring system is preferred for safeguarding Gas Centrifuge Enrichment Plants. However, if such a system is to be installed in a GCEP it must not impinge on plant operation or be intrusive. Since load cells are already part of the operational process and located outside the cascade hall their exploitation for safeguards purposes is an obvious development. The paper describes, through dynamic simulations, how transients would be observed in real-time mass balances when undeclared cascade operation takes place in a declared facility

Causal relationship between the right auditory cortex and speech-evoked frequency-following response: Evidence from combined tDCS and EEG

Speech-evoked frequency-following response (FFR) reflects the neural encoding of speech periodic information in the human auditory systems. FFR is of fundamental importance for pitch and speech perception and serves as clinical biomarkers for various auditory and language disorders. While it is suggested that the main neural source of FFR is in the auditory brainstem, recent studies have shown a cortical contribution to FFR predominantly in the right hemisphere. However, it is still unclear whether auditory cortex and FFR are causally related. The aim of this study was to establish this causal relationship using a combination of transcranial direct current stimulation (tDCS) and scalp-recorded electroencephalography (EEG). We applied tDCS over the left and right auditory cortices in right-handed normal-hearing participants and examined the after-effects of tDCS on FFR using EEG during monaural listening to a repeatedly-presented speech syllable. Our results showed that: (1) before tDCS was applied, participants had greater FFR magnitude when they listened to speech from the left than the right ear, illustrating right-lateralized hemispheric asymmetry for FFR; (2) anodal and cathodal tDCS applied over the right, but not left, auditory cortex significantly changed FFR magnitudes compared to the sham stimulation; specifically, such after-effects occurred only when participants listened to speech from the left ear, emphasizing the right auditory cortical contributions along the contralateral pathway. The current finding thus provides the first causal evidence that validates the relationship between the right auditory cortex and speech-evoked FFR and should significantly extend our understanding of speech encoding in the brain

EPR Steering Inequalities from Entropic Uncertainty Relations

We use entropic uncertainty relations to formulate inequalities that witness Einstein-Podolsky-Rosen (EPR) steering correlations in diverse quantum systems. We then use these inequalities to formulate symmetric EPR-steering inequalities using the mutual information. We explore the differing natures of the correlations captured by one-way and symmetric steering inequalities, and examine the possibility of exclusive one-way steerability in two-qubit states. Furthermore, we show that steering inequalities can be extended to generalized positive operator valued measures (POVMs), and we also derive hybrid-steering inequalities between alternate degrees of freedom.Comment: 10 pages, 2 figure

A model for the screen printing of Newtonian fluids

A preliminary investigation into aspects of the off-contact screen-printing process is presented. A mathematical model for the printing of a thin film of Newtonian fluid is proposed, in which the screen is modelled as a permeable membrane, and the entire region above and below the screen is flooded. By drawing upon widely used industrial circuit printing practices, the distinguished limit of greatest interest to this industry is identified. Numerical and asymptotic solutions of this distinguished limit are presented that reproduce many of the features observed in industrial screen-printing

Relationship between speech-evoked neural responses and perception of speech in noise in older adults

Speech-in-noise (SPIN) perception involves neural encoding of temporal acoustic cues. Cues include temporal fine structure (TFS) and envelopes that modulate at syllable (Slow-rate ENV) and fundamental frequency (F0-rate ENV) rates. Here the relationship between speech-evoked neural responses to these cues and SPIN perception was investigated in older adults. Theta-band phase-locking values (PLV) that reflect cortical sensitivity to Slow-rate ENV and peripheral/brainstem frequency-following responses phase-locked to F0-rate ENV (FFRENV_F0) and TFS (FFRTFS) were measured from scalp-EEG responses to a repeated speech syllable in steady-state speech-shaped (SpN) and 16-speaker babble (BbN) noises. The results showed that: 1) SPIN performance and PLV were significantly higher under SpN than BbN, implying differential cortical encoding may serve as the neural mechanism of SPIN performance that varies as a function of noise types; 2) PLV and FFRTFS at resolved harmonics were significantly related to good SPIN performance, supporting the importance of phase-locked neural encoding of Slow-rate ENV and TFS of resolved harmonics during SPIN perception; 3) FFRENV_F0 was not associated to SPIN performance until audiometric threshold was controlled for, indicating that hearing loss should be carefully controlled when studying the role of neural encoding of F0-rate ENV. Implications are drawn with respect to fitting auditory prostheses

Macroscopic modelling of the surface tension of polymer-surfactant systems

Polymer-surfactant mixtures are increasingly being used in a wide range of applications. Weakly-interacting systems, such as SDS/PEO and SDS/PVP, comprise ionic surfactants and neutral polymers, while strongly-interacting systems, such as SDS/POLYDMDAAC and C12TAB/NaPSS, comprise ionic surfactants and oppositely charged ionic polymers. The complex nature of interactions in the mixtures leads to interesting and surprising surface tension profiles as the concentrations of polymer and surfactant are varied. The purpose of our research has been to develop a model to explain these surface tension profiles and to understand how they relate to the formation of different complexes in the bulk solution. In this paper we shouw how an existing model based on the law of mass action can be extended to model the surface tension of weakly-interacting systems, and we also extend it further to produce a model for the surface tension of strongly interacting systems. Applying the model to a variety of strongly-interacting systems gives remarkable agreement with the experimental results. The model provides a sound theoretical basis for comparing and contrasting the behaviour of different systems and greatly enhances our understanding of the features observed

Star Formation Histories of Nearby Elliptical Galaxies. II. Merger Remnant Sample

This work presents high $S/N$ spectroscopic observations of a sample of six suspected merger remnants, selected primarily on the basis of H{\sc i} tidal debris detections. Single stellar population analysis of these galaxies indicates that their ages, metallicities, and $\alpha$-enhancement ratios are consistent with those of a representative sample of nearby elliptical galaxies. The expected stellar population of a recent merger remnant, young age combined with low [$\alpha$/Fe], is not seen in any H{\sc i}-selected galaxy. However, one galaxy (NGC~2534), is found to deviate from the $Z$-plane in the sense expected for a merger remnant. Another galaxy (NGC~7332), selected by other criteria, best matches the merger remnant expectations.Comment: 12 pages, 10 figures, accepted by A

High Tunnel Pole Bean Evaluation

There are two major types of green beans: bush or pole. Bush are short, erect plants (determinate) with a uniform pod set resulting in a short harvest season. Pole beans are trained on poles, fence, or string, and grow 7 to 8 ft in height and bear fruit continuously (indeterminate) requiring only one field planting. Further, the consumer perceives pole beans, with its longer pod, to be of superior quality. Our objective was to evaluate two pole bean varieties: Fortex, an extra long pod (11 in.) 60 day maturity, and Blue Lake, a standard pole bean variety, 6 to 7 in. round pod with 55-day maturity. Also, we wished to compare high tunnel production with field production and obtain two crops in the high tunnel by double cropping