scholarly journals Spatiotemporal coupling of attosecond pulses

2019 ◽  
Vol 116 (11) ◽  
pp. 4779-4787 ◽  
Author(s):  
Hampus Wikmark ◽  
Chen Guo ◽  
Jan Vogelsang ◽  
Peter W. Smorenburg ◽  
Hélène Coudert-Alteirac ◽  
...  
Keyword(s):  
Simple Analytical Model ◽  
Gaussian Optics ◽  
Spatial Properties ◽  
Light Pulses ◽  
Odd Order ◽  
Attosecond Pulses ◽  
Chromatic Aberrations ◽  
Extreme Uv ◽  
Temporal And Spatial ◽  
Uv Range

The shortest light pulses produced to date are of the order of a few tens of attoseconds, with central frequencies in the extreme UV range and bandwidths exceeding tens of electronvolts. They are often produced as a train of pulses separated by half the driving laser period, leading in the frequency domain to a spectrum of high, odd-order harmonics. As light pulses become shorter and more spectrally wide, the widely used approximation consisting of writing the optical waveform as a product of temporal and spatial amplitudes does not apply anymore. Here, we investigate the interplay of temporal and spatial properties of attosecond pulses. We show that the divergence and focus position of the generated harmonics often strongly depend on their frequency, leading to strong chromatic aberrations of the broadband attosecond pulses. Our argument uses a simple analytical model based on Gaussian optics, numerical propagation calculations, and experimental harmonic divergence measurements. This effect needs to be considered for future applications requiring high-quality focusing while retaining the broadband/ultrashort characteristics of the radiation.

Temporal and spatial properties of some deep moonquake clusters

2007 ◽  
Vol 112 (E9) ◽  
Author(s):  
R. C. Bulow ◽  
C. L. Johnson ◽  
B. G. Bills ◽  
P. M. Shearer
Keyword(s):  
Spatial Properties ◽  
Temporal And Spatial

scholarly journals Analyzing Space–Time Coherence in Precipitation Seasonality across Different European Climates

2020 ◽  
Vol 12 (1) ◽  
pp. 171
Author(s):  
Maria Lanfredi ◽  
Rosa Coluzzi ◽  
Vito Imbrenda ◽  
Maria Macchiato ◽  
Tiziana Simoniello
Keyword(s):  
Annual Cycle ◽  
Progressive Deformation ◽  
Precipitation Regime ◽  
Equilibrium Conditions ◽  
Spatial Properties ◽  
Spatial Features ◽  
Precipitation Seasonality ◽  
Temporal And Spatial ◽  
Average Annual Precipitation ◽  
Simulated Scenario

Seasonality is a fundamental feature of environmental systems which critically depend on the climate annual cycle. The regularity of the precipitation regime, in particular, is a basic factor to sustain equilibrium conditions. An incomplete or biased understanding of precipitation seasonality, in terms of temporal and spatial properties, could severely limit our ability to respond to climate risk, especially in areas with limited water resources or fragile ecosystems. Here, we analyze precipitation data from the Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) at 0.050 resolution to study the spatial features of the precipitation seasonality across different climate zones in Central-Southern Europe during the period 1981–2018. A cluster analysis of the average annual precipitation cycle shows that seasonality under the current climate can be synthesized in the form of a progressive deformation process of the annual cycle, which starts from the northernmost areas with maximum values in summer and ends in the south, where maximum values are recorded in winter. Our analysis is useful to detect local season-dependent changes, enhancing our understanding of the geography of climate change. As an example of application to this issue, we discuss the seasonality analysis in a simulated scenario based on IPCC projections.

scholarly journals Diel changes in acoustic and catch estimates of krill biomass

2009 ◽  
Vol 66 (6) ◽  
pp. 1318-1325 ◽  
Author(s):  
Yvan Simard ◽  
Marc Sourisseau
Keyword(s):  
Spatial Scales ◽  
Target Strength ◽  
Night Time ◽  
Diel Changes ◽  
Strobe Light ◽  
Light Pulses ◽  
Diel Vertical Migrations ◽  
Temporal And Spatial ◽  
The Difference ◽  
Fixed Distribution

Abstract Simard, Y., and Sourisseau, M. 2009. Diel changes in acoustic and catch estimates of krill biomass. – ICES Journal of Marine Science, 66: 1318–1325. Krill-biomass estimates can be compromised by diel variabilities in acoustic backscatter and the catch efficiencies of various nets. This paper describes an effort to quantify these variabilities at fine temporal and spatial scales during a three-day experiment at a fixed location, using high-resolution, stratified Bioness samples and echo-integration, and assuming a fixed distribution of krill orientations. Night-time catches in the krill scattering layer (SL) were 15 times the acoustic estimates. The situation was reversed during daytime, when the acoustic estimates in the SL were 5 times larger than the catches. This collectively resulted in a ±10‐dB gradual diel cycle in the difference of vertically integrated biomass from both sampling methods. Use of a strobe light on the Bioness reduced avoidance of the net by krill and significantly increased (×10) daytime catches in the SL, but had no significant effect on night-time catches. The difference in volume-backscattering strength at 120 and 38 kHz (ΔSv120–38) in the densest parts of the SL agreed with predictions using a target-strength (TS) model and an assumed normal distribution of tilt (mean θ = 11°; s.d. = 4°). The ΔSv120–38 was smaller for lower densities and during night-time. It appears that the θ and, therefore, TS distributions of krill significantly change during their diel vertical migrations. At twilight and at night, when they are feeding and swimming vertically, they exhibit lower mean TS and ΔSv120–38 and react less to strong strobe-light pulses, in contrast to daytime. Diel patterns in TS and net avoidance should be taken into account in krill-biomass assessments that use round the clock acoustic-survey data and multi-frequency TS models for target classification.

scholarly journals The Emotional Glue of the Senses: Affective Certainty and Congruency in the Rubber Hand Illusion

2018 ◽  
Author(s):  
Maria Laura Filippetti ◽  
Louise P. Kirsch ◽  
Laura Crucianelli ◽  
Aikaterini Fotopoulou
Keyword(s):  
Multisensory Integration ◽  
Sensory Stimulation ◽  
Rubber Hand Illusion ◽  
Body Ownership ◽  
Top Down ◽  
Rubber Hand ◽  
Spatial Properties ◽  
Affective Quality ◽  
Temporal And Spatial

AbstractOur sense of body ownership relies on integrating different sensations according to their temporal and spatial congruency. Nevertheless, there is ongoing controversy about the role of affective congruency during multisensory integration, i.e. whether the stimuli to be perceived by the different sensory channels are congruent or incongruent in terms of their affective quality. In the present study, we applied a widely used multisensory integration paradigm, the Rubber Hand Illusion, to investigate the role of affective, top-down aspects of sensory congruency between visual and tactile modalities in the sense of body ownership. In Experiment 1 (N = 36), we touched participants with either soft or rough fabrics in their unseen hand, while they watched a rubber hand been touched synchronously with the same fabric or with a ‘hidden’ fabric of ‘uncertain roughness’. In Experiment 2 (N = 50), we used the same paradigm as in Experiment 1, but replaced the ‘uncertainty’ condition with an ‘incongruent’ one, in which participants saw the rubber hand being touched with a fabric of incongruent roughness and hence opposite valence. We found that certainty (Experiment 1) and congruency (Experiment 2) between the felt and vicariously perceived tactile affectivity led to higher subjective embodiment compared to uncertainty and incongruency, respectively, irrespective of any valence effect. Our results suggest that congruency in the affective top-down aspects of sensory stimulation is important to the multisensory integration process leading to embodiment, over and above temporal and spatial properties.

scholarly journals Static and Dynamic Presentation of Emotions in Different Facial Areas: Fear and Surprise Show Influences of Temporal and Spatial Properties

Psychology ◽  
2013 ◽  
Vol 04 (08) ◽  
pp. 663-668 ◽  
Author(s):  
Holger Hoffmann ◽  
Harald C. Traue ◽  
Kerstin Limbrecht-Ecklundt ◽  
Steffen Walter ◽  
Henrik Kessler
Keyword(s):  
Spatial Properties ◽  
Temporal And Spatial ◽  
Dynamic Presentation

Generation of high-order harmonics and attosecond pulses

2019 ◽  
pp. 326-342
Author(s):  
Anne L’Huillier
Keyword(s):  
Extreme Ultraviolet ◽  
High Order ◽  
Intense Laser ◽  
Single Atom ◽  
Light Pulses ◽  
High Order Harmonic ◽  
Attosecond Pulses ◽  
Intense Laser Radiation ◽  
Atom Level ◽  
The Time Domain

The interaction of atoms with intense laser radiation leads to the generation of high-order harmonics of the laser field. In the time domain, this corresponds to a train of pulses in the extreme ultraviolet range and with attosecond duration. The first section introduces the physics of high-order harmonic generation and attosecond pulses on the single atom level while the second section discusses phase matching and propagation effects. The attosecond time scale is that of the electron motion in atoms and molecules. Attosecond light pulses are used to study, for example, the dynamics of atomic or molecular photoionization. The third section will present an interferometric method developed for measuring attosecond pulses and discuss some of the applications, in particular concerning photoionization dynamics.

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