Propagating Coherent Acoustic Phonon Wavepackets in InMnAs/GaSb

We observe pronounced oscillations in the differential reflectivity of a ferromagnetic InMnAs/GaSb heterostructure using two-color pump-probe spectroscopy. Although originally thought to be associated with the ferromagnetism, our studies show that the oscillations instead result from changes in the position and frequency-dependent dielectric function due to the generation of coherent acoustic phonons in the ferromagnetic InMnAs layer and their subsequent propagation into the GaSb. Our theory accurately predicts the experimentally measured oscillation period and decay time as a function of probe wavelength.Comment: 4 pages, 4 figure

Resonance-like piezoelectric electron-phonon interaction in layered structures

We show that mismatch of the piezoelectric parameters between layers of multiple-quantum well structures leads to modification of the electron-phonon interaction. In particular, short-wavelength phonons propagating perpendicular to the layers with wavevector close to $2\pi n/d$, where $d$ is the period of the structure, induce a strong smoothly-varying component of the piezo-potential. As a result, they interact efficiently with 2D electrons. It is shown, that this property leads to emission of collimated quasi-monochromatic beams of high-frequency acoustic phonons from hot electrons in multiple-quantum well structures. We argue that this effect is responsible for the recently reported monochromatic transverse phonon emission from optically excited GaAs/AlAs superlattices, and provide additional experimental evidences of this.Comment: 6 pages, 7 figure

A case-matched study of neurophysiological correlates to attention /working memory in people with somatic hypervigilance

Accepted 14 June 2016Somatic hypervigilance describes a clinical presentation in which people report more, and more intense, bodily sensations than is usual. Most explanations of somatic hypervigilance implicate altered information processing, but strong empirical data are lacking. Attention and working memory are critical for information processing, and we aimed to evaluate brain activity during attention/working memory tasks in people with and without somatic hypervigilance. Method: Data from 173 people with somatic hypervigilance and 173 controls matched for age, gender, handedness, and years of education were analyzed. Event-related potential (ERP) data, extracted from the continuous electroencephalograph recordings obtained during performance of the Auditory Oddball task, and the Two In A Row (TIAR) task, for N1, P2, N2, and P3, were used in the analysis. Between-group differences for P3 amplitude and N2 amplitude and latency were assessed with two-tailed independent t tests. Between-group differences for N1 and P2 amplitude and latency were assessed using mixed, repeated measures analyses of variance (ANOVAs) with group and Group × Site factors. Linear regression analysis investigated the relationship between anxiety and depression and any outcomes of significance. Results: People with somatic hypervigilance showed smaller P3 amplitudes—Auditory Oddball task: t(285) = 2.32, 95% confidence interval, CI [3.48, 4.47], p = .026, d = 0.27; Two-In-A-Row (TIAR) task: t(334) = 2.23, 95% CI [2.20; 3.95], p = .021, d = 0.24—than case-matched controls. N2 amplitude was also smaller in people with somatic hypervigilance—TIAR task: t(318) = 2.58, 95% CI [0.33, 2.47], p = .010, d = 0.29—than in case-matched controls. Neither depression nor anxiety was significantly associated with any outcome. Conclusion: People with somatic hypervigilance demonstrated an event-related potential response to attention/working memory tasks that is consistent with altered information processing.Carolyn Berryman, Vikki Wise, Tasha R. Stanton, Alexander McFarlane and G. Lorimer Mosele

Correlation of Cochlear Pathology with Auditory Brainstem and Cortical Responses in Cats with High Frequency Hearing Loss

Newborn kittens were treated with the aminoglycoside amikacin to produce a bilateral high frequency cochlear hearing loss. The degree and stability of hearing loss were confirmed by recording auditory brainstem evoked potentials (ABR audiograms). After maturation, cochleotopic frequency representation within primary auditory cortex (Al) was mapped using standard microelectrode recording techniques. The cochlear sensory epithelium was assessed with SEM and the pattern of damage compared with the ABR audiograms and cortical frequency maps. Amikacin treatment resulted in various patterns of haircell damage towards the base of the cochlea. A relatively abrupt transition between damaged and undamaged haircell regions resulted in an ABR audiogram with normal threshold to low frequencies and a high frequency elevation with a steep cut-off slope. In the cortical map, low frequency representation was normal, but anterior areas contained only neurons tuned to a common frequency which corresponded to the frequency-place position of the boundary of the haircell lesion and to the cut-off frequency of the audiogram. A large transitional zone of the cochlear lesion correlated with a gradual cut-off slope to the audiogram and again a remapping of the anterior and normally high frequency area to a common lower frequency. Haircell loss or damage (i.e. disarray of stereocilia) in lower frequency regions of the cochlea correlated with a significant reorganization of the lower frequency bands in the cortical map. We conclude from this study that the pattern of cochleotopic organization of the cortex is dependent on the pattern of activity in the ascending sensory pathway during early stages of development

Three-dimensional modeling of acoustic backscattering from fluid-like zooplankton

Author Posting. © Acoustical Society of America, 2002. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 111 (2002): 1197-1210, doi:10.1121/1.1433813.Scattering models that correctly incorporate organism size and shape are a critical component for the remote detection and classification of many marine organisms. In this work, an acoustic scattering model has been developed for fluid-like zooplankton that is based on the distorted wave Born approximation (DWBA) and that makes use of high-resolution three-dimensional measurements of the animal's outer boundary shape. High-resolution computerized tomography (CT) was used to determine the three-dimensional digitizations of animal shape. This study focuses on developing the methodology for incorporating high-resolution CT scans into a scattering model that is generally valid for any body with fluid-like material properties. The model predictions are compared to controlled laboratory measurements of the acoustic backscattering from live individual decapod shrimp. The frequency range used was 50 kHz to 1 MHz and the angular characteristics of the backscattering were investigated with up to a 1° angular resolution. The practical conditions under which it is necessary to make use of high-resolution digitizations of shape are assessed.This work was supported in part by the Woods Hole Oceanographic Institution Education Office

Distributed situation awareness in dynamic systems: Theoretical development and application of an ergonomics methodology

The purpose of this paper is to propose foundations for a theory of situation awareness based on the analysis of interactions between agents (i.e., both human and non-human) in subsystems. This approach may help promote a better understanding of technology-mediated interaction in systems, as well as helping in the formulation of hypotheses and predictions concerning distributed situation awareness. It is proposed that agents within a system each hold their own situation awareness which may be very different from (although compatible with) other agents. It is argued that we should not always hope for, or indeed want, sharing of this awareness, as different system agents have different purposes. This view marks situation awareness as a 1 dynamic and collaborative process that binds agents together on tasks on a moment-by-moment basis. Implications of this viewpoint for development of a new theory of, and accompanying methodology for, distributed situation awareness are offered

Detecting the (Quasi-)Two-Body Decays of τ\tau Leptons in Short-Baseline Neutrino Oscillation Experiments

Novel detector schemes are proposed for the short-baseline neutrino experiments of next generation, aimed at exploring the large-$\Delta m^2$ domain of \omutau oscillations in the appearance mode. These schemes emphasize good spectrometry for charged particles and for electromagnetic showers and efficient reconstruction of \ypi_gg decays. The basic elements are a sequence of relatively thin emulsion targets, immersed in magnetic field and interspersed with electronic trackers, and a fine-grained electromagnetic calorimeter built of lead glass. These elements act as an integral whole in reconstructing the electromagnetic showers. This conceptual scheme shows good performance in identifying the $\tau$ (quasi-)two-body decays by their characteristic kinematics and in selecting the electronic decays of the $\tau$.Comment: 34 pages, 8 figure

Polymer Brush‐Modified Microring Resonators for Partition‐Enhanced Small Molecule Chemical Detection

Silicon photonic microring resonators have emerged as a promising technology for the sensitive detection of biological macromolecules, including proteins and nucleic acids. However, not all species of interest are large biologics that can be targeted by highly specific capture agents. For smaller organic chemicals, including many toxic and regulated species, a general approach to improving sensitivity would be desirable. By functionalizing the surface of silicon photonic microring resonators with polymer brushes, small molecules can selectively partition into the surface‐confined sensing region of the optical resonators. This in turn leads to response enhancements in excess of 1000% percent, relative to non‐functionalized sensors, for representative targets including 4‐methylumbelliferyl phosphate, a simulant for highly toxic organophosphates, Bisphenol A, an industrial pollutant, as well as other small organic analytes of interest. There are many polymer brush chemistries compatible with silicon resonators, making this a general strategy towards tuning sensor selectivity and specificity by optimizing interactions between the agent(s) of interest and the polymer construct.Polymer brush‐modified microring resonators sensors can be utilized to enhance sensitivity and specificity for the detection of small molecule organic chemicals.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136268/1/slct201700082.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136268/2/slct201700082-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136268/3/slct201700082_am.pd