| 1. |
- Bylander, Jonas, 1978, et al.
(author)
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Pulse imaging and nonadiabatic control of solid-state artificial atoms
- 2009
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In: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 80:22, s. 220506-
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Journal article (peer-reviewed)abstract
- Transitions in an artificial atom, driven nonadiabatically through an energy-level avoided crossing, can be controlled by carefully engineering the driving protocol. We have driven a superconducting persistent-current qubit with a large-amplitude radio-frequency field. By applying a biharmonic wave form generated by a digital source, we demonstrate a mapping between the amplitude and phase of the harmonics produced at the source and those received by the device. This allows us to image the actual wave form at the device. This information is used to engineer a desired time dependence, as confirmed by the detailed comparison with a simulation. © 2009 The American Physical Society.
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| 2. |
- Lemme, Max C., 1970-, et al.
(author)
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Gate-Activated Photoresponse in a Graphene p-n Junction
- 2011
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In: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 11:10, s. 4134-4137
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Journal article (peer-reviewed)abstract
- We study photodetection in graphene near a local electrostatic gate, which enables active control of the potential landscape and carrier polarity. We find that a strong photoresponse only appears when and where a p-n junction is formed, allowing on-off control of photodetection. Photocurrents generated near p-n junctions do not require biasing and can be realized using submicrometer gates. Locally modulated photoresponse enables a new range of applications for graphene-based photodetectors including, for example, pixilated infrared imaging with control of response on subwavelength dimensions.
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| 3. |
- Wang, Xiangjun, et al.
(author)
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Growth and characterization of Na0.5K0.5NbO3 thin films on polycrystalline Pt80Ir20 substrates
- 2002
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In: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 17:5, s. 1183-1191
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Journal article (peer-reviewed)abstract
- Na0.5K0.5NbO3 thin films have been deposited onto textured polycrystalline Pt80Ir20 substrates using radio frequency magnetron sputtering. Films were grown in off- and on-axis positions relative to the target at growth temperatures of 500-700 degreesC and sputtering pressures of 1-7 Pa. The deposited films were found to be textured, displaying a mixture of two orientations (001) and (101). Films grown on-axis showed a prefered (001) orientation, while the off-axis films had a (101) orientation. Scanning electron microscopy showed that the morphology of the films was dependent on the substrate position and sputtering pressure. The low-frequency (10 kHz) dielectric constants of the films were found to be in the range of approximately 490-590. Hydrostatic piezoelectric measurements showed that the films were piezoelectric in the as-deposited form with a constant up to 14.5 pC/N.
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| 4. |
- Winkler, Dag, 1957, et al.
(author)
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On the feasibility of constructing an imaging array of slot-antennas integrated with SIS mixers
- 1986
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In: Proceedings of an ESA Workshop on a Space-Borne Sub-Millimetre Astronomy Mission. ; , s. 277-283
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Conference paper (peer-reviewed)abstract
- Several important developments have been made for the realization of array mixer receivers for imaging in radio astronomy: preliminary experiments on a 700 GHz SIS mixer have been performed and imaging at 31 GHz using an array of tapered slot antennas equipped with diode detectors has been demonstrated. These developments are briefly described
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| 5. |
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| 6. |
- Mishra, Sushmit, 1981-
(author)
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Exploring Cognitive Spare Capacity : Executive Processing of Degraded Speech
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Cognitive resources, specifically working memory capacity are used for listening to speech, especially in noise. Cognitive resources are limited, and if listeners allocate a greater share of these resources to recovering the input signal in noise, fewer resources are available for interpreting and encoding its linguistic content. Although the importance of CSC for individual success in communicative situations has been acknowledged, this concept has not hitherto been explored experimentally. In this thesis, a CSC test (CSCT) was developed and administered to young adults with normal hearing and older adults with age-related hearing loss. CSCT required executive processing of speech at different memory loads with and without visual cues in different noise conditions. A free recall task using the same material was administered for comparison purposes and a battery of cognitive tests was administered to understand the relation between CSC and established cognitive concepts. The aims of the thesis were to investigate how CSC is influenced by 1) different executive demands and memory loads; 2) background noise; 3) visual cues; 4) aging and concomitant hearing loss. The results showed that 1) CSC was sensitive to memory load, and updating demands reduced CSC more than inhibition demands; 2) CSC was reduced in background noise compared to quiet; 3) visual cues enhanced CSC especially in noise; 4) CSC was reduced with ageing and concomitant hearing loss especially when visual cues were absent, memory demands were increased and background noise was speech-like. The main finding of this thesis was that visual cues enhanced CSC for older individuals with hearing loss, specifically in adverse listening conditions. This demonstrates the importance of audiovisual testing in audiological assessment. Further, specific cognitive resources depleted during listening in noise were at least partially compensated by other cognitive functions. This thesis is the first step towards a theoretical understanding of CSC and in future, tests of CSC may play a crucial role in planning rehabilitation of persons with hearing loss.
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| 7. |
- Pichora-Fuller, Kathleen M., et al.
(author)
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Hearing Impairment and Cognitive Energy: The Framework for Understanding Effortful Listening (FUEL)
- 2016
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In: Ear and Hearing. - : LIPPINCOTT WILLIAMS & WILKINS. - 0196-0202 .- 1538-4667. ; 37, s. 5S-27S
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Journal article (peer-reviewed)abstract
- The Fifth Eriksholm Workshop on "Hearing Impairment and Cognitive Energy" was convened to develop a consensus among interdisciplinary experts about what is known on the topic, gaps in knowledge, the use of terminology, priorities for future research, and implications for practice. The general term cognitive energy was chosen to facilitate the broadest possible discussion of the topic. It goes back to Titchener (1908) who described the effects of attention on perception; he used the term psychic energy for the notion that limited mental resources can be flexibly allocated among perceptual and mental activities. The workshop focused on three main areas: (1) theories, models, concepts, definitions, and frameworks; (2) methods and measures; and (3) knowledge translation. We defined effort as the deliberate allocation of mental resources to overcome obstacles in goal pursuit when carrying out a task, with listening effort applying more specifically when tasks involve listening. We adapted Kahnemans seminal (1973) Capacity Model of Attention to listening and proposed a heuristically useful Framework for Understanding Effortful Listening (FUEL). Our FUEL incorporates the well-known relationship between cognitive demand and the supply of cognitive capacity that is the foundation of cognitive theories of attention. Our FUEL also incorporates a motivation dimension based on complementary theories of motivational intensity, adaptive gain control, and optimal performance, fatigue, and pleasure. Using a three-dimensional illustration, we highlight how listening effort depends not only on hearing difficulties and task demands but also on the listeners motivation to expend mental effort in the challenging situations of everyday life.
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| 8. |
- Rudner, Mary, et al.
(author)
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Good working memory capacity facilitates long-term memory encoding of speech in stationary noise
- 2015
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Conference paper (peer-reviewed)abstract
- Background noise makes listening more cognitively demanding, especially for persons with hearingimpairment, and this seems to aect memory encoding. It is not clear whether this decrement can berestored by providing visual cues. In the present study, we investigated whether long term memoryencoding of speech, in quiet and in background noise adjusted to retain intelligibility, improves whenthe talkers face is visible, and whether such an enhancement is associated with working memorycapacity. Twenty adults with normal hearing in Experiment 1 and 24 adults with hearing loss inExperiment 2 listened to lists of 13 two-digit numbers, with or without seeing the talkers face, andthen recalled as many numbers as possible in any order. The lists were presented in quiet as wellin a steady-state speech-weighted noise and the International Speech Testing Signal at a signal-tonoiseratio individually adapted to give an intelligibility level of approximately 90%. Amplicationcompensated for loss of audibility. Working memory capacity was measured using the reading spantest. Seeing the talkers face did enhance free recall performance. However, whereas the eect size foradults with normal hearing was large, for adults with hearing impairment it was small. Further, therewas no evidence that visual cues specically compensated for performance decrements due to noiseor serial position and there was no evidence of an association between working memory capacity andperformance with visual cues. However, good working memory capacity did improve performance forearly list items, reecting facilitation of long-term memory encoding, for both groups when stimuliwere presented in steady-state noise. For participants with hearing impairment, good working memorycapacity was associated with good performance on late list items in quiet, reecting facilitationof working memory encoding. This pattern of results indicates that steady-state background noisereduces the cognitive capacity available for the long-term memory encoding of speech that is necessaryfor enduring retention of spoken information, irrespective of hearing status, but provides no evidencethat this is specically compensated for by visual cues. It also demonstrates that for individuals withhearing impairment, short term retention of speech heard even under the most favourable conditionsis a function of individual working memory capacity. These ndings support and extend the Ease ofLanguage Understanding Model.
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| 9. |
- Rönnberg, Jerker, et al.
(author)
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Speech in noise and ease of language understanding : When and how working memory capacity plays a role
- 2012
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In: The Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 0001-4966.
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Conference paper (peer-reviewed)abstract
- A working memory based model for Ease of Language Understanding (ELU) has been developed (Rönnberg, 2003; Rönnberg et al., 2008; Rönnberg et al., 2011). It predicts that speech understanding in adverse, mismatching noise conditions is dependent on explicit processing resources such as working memory capacity (WMC). This presentation will examine the details of this prediction by addressing some recent data on (1) how brainstem responses are modulated by working memory load and WMC, (2) how cortical correlates of speech understanding in noise are modulated by WMC, and (3) how WMC determines episodic long-term memory for spoken discourse masked by speech.
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| 10. |
- Selinder, TI, et al.
(author)
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Microstructure and microwave loss studies on epitaxial YBa2Cu3Ox thin films
- 1992
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In: High Tc superconductor thin films. - 0444893539 ; , s. 219-224
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Conference paper (peer-reviewed)abstract
- Thin YBa2Cu3Ox films were grown on SrTiO3 or LaAlO3 single crystals by dc-magnetron reactive sputtering in argon/oxygen gas mixtures. Deposition temperatures ranged from 540 °C to 780 °C. After deposition and subsequent cool down, films grown above 680 °C are superconducting below 86–88 K. All films are oriented with the [001] direction parallel to the [001] substrate normal. The best films have critical current densities well above 106 A/cm2, and effective 6 GHz surface resistance values below 300 μω, at 77 K. Despite good electrical properties, the films are littered with copper rich particles on a smooth and epitaxial single crystalline surface. Cross-section Transmission Electron Microscopy (X-TEM) was used to study the crystalline quality on a microscopic level, and the nature of particles occurring on/in the as grown film. Small misaligned YBa2Cu3Ox grains often occur in the films. The large copper rich particles on the film surface seem to have nucleated at such grains on the film surface. Their occurrence can, at least partly, be explained by a nonstoichiometric flow to the substrate. The number density of the particles decreased with increasing growth temperature but the volume density seemed to be constant in the investigated temperature interval.
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