Visual adaptation enhances action sound discrimination

Prolonged exposure, or adaptation, to a stimulus in one modality can bias, but also enhance, perception of a subsequent stimulus presented within the same modality. However, recent research has also found that adaptation in one modality can bias perception in another modality. Here we show a novel crossmodal adaptation effect, where adaptation to a visual stimulus enhances subsequent auditory perception. We found that when compared to no adaptation, prior adaptation to visual, auditory or audiovisual hand actions enhanced discrimination between two subsequently presented hand action sounds. Discrimination was most enhanced when the visual action ‘matched’ the auditory action. In addition, prior adaptation to a visual, auditory or audiovisual action caused subsequent ambiguous action sounds to be perceived as less like the adaptor. In contrast, these crossmodal action aftereffects were not generated by adaptation to the names of actions. Enhanced crossmodal discrimination and crossmodal perceptual aftereffects may result from separate mechanisms operating in audiovisual action sensitive neurons within perceptual systems. Adaptation induced crossmodal enhancements cannot be explained by post-perceptual responses or decisions. More generally, these results together indicate that adaptation is a ubiquitous mechanism for optimizing perceptual processing of multisensory stimuli

A biogeographical appraisal of the threatened South East Africa Montane Archipelago ecoregion

Recent biological surveys of ancient inselbergs in southern Malawi and northern Mozambique have led to the discovery and description of many species new to science, and overlapping centres of endemism across multiple taxa. Combining these endemic taxa with data on geology and climate, we propose the ‘South East Africa Montane Archipelago’ (SEAMA) as a distinct ecoregion of global biological importance. The ecoregion encompasses 30 granitic inselbergs reaching > 1000 m above sea level, hosting the largest (Mt Mabu) and smallest (Mt Lico) mid-elevation rainforests in southern Africa, as well as biologically unique montane grasslands. Endemic taxa include 127 plants, 45 vertebrates (amphibians, reptiles, birds, mammals) and 45 invertebrate species (butterflies, freshwater crabs), and two endemic genera of plants and reptiles. Existing dated phylogenies of endemic animal lineages suggests this endemism arose from divergence events coinciding with repeated isolation of these mountains from the pan-African forests, together with the mountains’ great age and relative climatic stability. Since 2000, the SEAMA has lost 18% of its primary humid forest cover (up to 43% in some sites)—one of the highest deforestation rates in Africa. Urgently rectifying this situation, while addressing the resource needs of local communities, is a global priority for biodiversity conservation

Kev X-Ray Imaging Of A Fs Laser Plasma With A Spherically Curved Crystal

Images of a 130fs laser produced Ta-plasma were obtained with a spherically curved Mica crystal in four narrow spectral bands simultaneously. These are to our knowledge the first published x-ray images of a fs plasma. Also Mica was used for the first time as the imaging crystal. The resolved plasma size in the experiment (50 μm · 90 μm) agrees with ray-tracing calculations and corresponds to the actual source size in our current setup. The four spectral bands of imaging are due to the strong Mica reflectivity in higher Bragg diffraction orders. All contributing bands have an energy higher than 1keV. Several laser shots were accumulated to achieve the required flux on the detector. Source spectroscopy was conducted to verify the source emission and the plasma density during the interaction with the 130fs laser pulse. Based on our experimental data the luminosity of crystal imaging is compared to a pinhole camera

X-Ray Flash Microprobing Of Structural Dynamics In Exploding Crystals

We describe a new technique for investigating transient structural changes in solid materials involving short pulses of hard x-rays emitted by laser produced plasmas. Using a subpicosecond terawatt scale laser system, this technique promises to be simple and broadly applicable to both single-crystal and polycrystalline samples of thickness up to millimeters and mean atomic number up to approximately 30. Spatial resolutions of order 10 μm should be possible. Of particular interest are the so-called energetic materials, chemical high explosives, whose initiation and reaction dynamics in relation to physical microstructure are poorly known

Ultrafast Semiconductor Laser Diode Seeded Cr:Lisaf Regenerative Amplifier System

An ultrafast modelocked semiconductor laser diode system has been used to seed a flashlamp pumped Cr:LiSAF regenerative amplifier system, producing subpicosecond pulses with millijoule output pulse energy. This system has the potential to eliminate argon ion pumped based ultrafast laser systems

10-Tw Femtosecond Laser Plasma Facility

The availability of ultrashort (100 fs) high intensity lasers capable of producing focused intensities in excess of 10 18 W/cm 2 provides many new opportunities in studying the interaction of radiation with matter. We describe a new laser plasma facility constructed around a Cr:LiSAF laser system currently capable of output energies of approximately 1 J in times of approximately 100 fs. This facility will be directed initially towards basic studies of the interaction of intense ultrashort laser pulses with dense plasmas, and the generation and application of intense hard x-ray point sources. The laser system we have developed for this facility, uses the new solid- state laser material, Cr:LiSAF. This material has many advantages for the generation of intense ultrashort laser pulses. The spectral gain bandwidth is sufficiently broad for the amplification of pulses shorter than 100 fs in duration. Its florescence lifetime is long enough to permit the use of conventional flashlamp pumping, and its emission cross- section is such that it provides small signal gains high enough to allow its use in high powered chirped pulsed amplification laser architectures. The material can now be fabricated into laser rods up to 25 mm in diameter with low scattering losses and its Cr concentrations can be varied to optimize the small signal gain for specific pump cavities. These factors taken together allow the design of a 100 fs high intensity oscillator-laser system that is simpler in architecture than those based on Ti:sapphire or KrF. Moreover the use of Cr:LiSAF laser crystal elements should enable the generation of much higher powers. In principle as high as 1 PW should be achievable with a laboratory with this approach. Modifications currently being implemented onto our Cr:LiSAF laser system include improvements to pulse contrast, energy extraction, beam uniformity and focusability. The system will soon be incorporated with a 52- port precision target chamber that will be equipped with a broad array of x ray and plasma diagnostics. Several research programs are being designed around this facility. Two of these programs, those relating to the use of hard x rays for the analysis of shock phenomena in solids and the general physics of extremely high magnetic fields are presented

Extension Of Femtosecond Cr:Lisaf Systems To The 100-Tw Level

The availability of ultrashort (100 fs or shorter) high intensity lasers capable of producing focused intensities in excess of 10 18 W/cm 2 provides many new opportunities in studying the interaction of radiation with matter. In this paper we describe and compare three methods for generating these high intensity pulses into the 100 TW power range. In addition, we describe in detail the use of Cr:LiSAF as an amplifying medium for this type of laser system. This work also includes descriptions of the factors that affect the performance of short pulse laser systems, especially with regard to Cr:LiSAF. Techniques of how to overcome the obstacles created by these factors are also discussed together with experimental data regarding the bandwidth limits of an existing regenerative amplifier

Measurements of Absolute, SI Traceable Lunar Irradiance with the Airborne LUnar Spectral Irradiance (air LUSI) Instrument

The Moon is a very useful calibration target for Earth-observing sensors in orbit because its surface is radiometrically stable and it has a radiant flux comparable to Earth scenes. To predict the lunar irradiance given an illumination and viewing geometry, the United States Geological Survey (USGS) has developed the Robotic Lunar Observatory (ROLO) Model of exo-atmospheric lunar spectral irradiance. The USGS ROLO model represents the current most precise knowledge of lunar spectral irradiance and is used frequently as a relative calibration standard by space-borne Earth-observing sensors. However, its accuracy as an absolute reference may be limited to several percent and it is not SI-traceable. Advancing the model to be a more accurate absolute lunar reference requires new measurements. The objective of the airborne LUnar Spectral Irradiance (Air-LUSI) mission is to make highly accurate, SI-traceable measurements of lunar spectral irradiance in the VNIR spectral region from NASA’s high-altitude ER-2 aircraft, above 95% of the atmosphere. To that end, the Air-LUSI system uses a non-imaging telescope system that robotically tracks the Moon in flight, fiber-optic coupled to a stable spectrometer housed in an enclosure providing a robustly controlled environment. The spectrometer measures about 350 to 1050 nm at 3.8 nm resolution, with 0.8 nm sampling. The instrument is reproducibly stable to 0.3% and rigorously calibrated before and after campaigns and flights using a similar transfer standard spectrograph. An on-board LED source is used to monitor the instrument response during flight ascent and descent. Air-LUSI successfully conducted a Demonstration Flight Campaign on five consecutive nights from 12 to 17 November 2019, corresponding to lunar phase angles of about 10°, 21°, 34°, 46° and 59°. Each night, the Air-LUSI system observed the Moon from above 68,000 feet altitude for 30 to 40 minutes. To reach a target uncertainty for lunar irradiance of 0.5% (k=1), processing the raw data to exo-atmospheric lunar spectral irradiance required accounting for various known behaviors of the instrument, such as thermal and stray light corrections. Additional measures were taken to address variances idiosyncratic to the campaign and were factored into the measurement error budget. The resulting error budget currently stands at less than 1% over most of the VNIR range. This paper reviews the steps taken towards high accuracy results for Demonstration Flight Campaign, how they factored in the error budget, and how our uncertainty target can be met in future campaigns

A biogeographical appraisal of the threatened South East Africa Montane Archipelago ecoregion

Funder: Transglobe Expedition Trust (TET)Funder: African Butterfly Research Institute (ABRI)Funder: Jonathan and Jennifer Oppenheimer FoundationFunder: Global Challenges Research Fund pump-priming award (GCRF QR)Recent biological surveys of ancient inselbergs in southern Malawi and northern Mozambique have led to the discovery and description of many species new to science, and overlapping centres of endemism across multiple taxa. Combining these endemic taxa with data on geology and climate, we propose the ‘South East Africa Montane Archipelago’ (SEAMA) as a distinct ecoregion of global biological importance. The ecoregion encompasses 30 granitic inselbergs reaching > 1000 m above sea level, hosting the largest (Mt Mabu) and smallest (Mt Lico) mid-elevation rainforests in southern Africa, as well as biologically unique montane grasslands. Endemic taxa include 127 plants, 45 vertebrates (amphibians, reptiles, birds, mammals) and 45 invertebrate species (butterflies, freshwater crabs), and two endemic genera of plants and reptiles. Existing dated phylogenies of endemic animal lineages suggests this endemism arose from divergence events coinciding with repeated isolation of these mountains from the pan-African forests, together with the mountains’ great age and relative climatic stability. Since 2000, the SEAMA has lost 18% of its primary humid forest cover (up to 43% in some sites)—one of the highest deforestation rates in Africa. Urgently rectifying this situation, while addressing the resource needs of local communities, is a global priority for biodiversity conservation