Short-wavelength Radiation Research Articles

Influence of Plastic Covering on the Microclimate in Vineyards in the São Francisco River Valley Region

Abstract Data from field experiments conducted in table grape vineyards variety of Festival in Petrolina-PE in the period from September 19 to October 12, 2010 were used to evaluate the influence of plastic cover on microclimate conditions of vineyards in São Francisco River Valley region. Three treatments were studied: canopies without plastic cover (WC); with plastic cover positioned at 50 cm (PC50), and at 100 cm (PC100) above canopy. The results indicate that the plastic cover prevented the passage of about 40% of the global and net radiation, retained the relative humidity inside the canopy, generated an increase of air temperature and marked reduction in wind speed over the canopy of treatment PC50. However, treatment PC100 had a higher incidence of short wavelength and net radiation under canopy (on the berries) than WC and PC50 treatments, resulting in more favorable weather conditions, providing about 40% greater productivity in this treatment. Therefore, the vineyard with plastic cover placed at 100 cm above canopy represents a more suitable alternative to the climatic conditions of the region of the São Francisco River Valley.

High-order nonlinear optical processes in ablated carbon-containing materials: Recent approaches in development of the nonlinear spectroscopy using harmonic generation in the extreme ultraviolet range

The nonlinear spectroscopy using harmonic generation in the extreme ultraviolet range became a versatile tool for the analysis of the optical, structural and morphological properties of matter. The carbon-contained materials have shown the advanced properties among other studied species, which allowed both the definition of the role of structural properties on the nonlinear optical response and the analysis of the fundamental features of carbon as the attractive material for generation of coherent short-wavelength radiation. We review the studies of the high-order harmonic generation by focusing ultrashort pulses into the plasmas produced during laser ablation of various organic compounds. We discuss the role of ionic transitions of ablated carbon-containing molecules on the harmonic yield. We also show the similarities and distinctions of the harmonic and plasma spectra of organic compounds and graphite. We discuss the studies of the generation of harmonics up to the 27th order (λ = 29.9 nm) of 806 nm radiation in the boron carbide plasma and analyze the advantages and disadvantages of this target compared with the ingredients comprising B4C (solid boron and graphite) by comparing plasma emission and harmonic spectra from three species. We also show that the coincidence of harmonic and plasma emission wavelengths in most cases does not cause the enhancement or decrease of the conversion efficiency of this harmonic.

Easily Processable Temperature-Responsive Infrared-Reflective Polymer Coatings

A temperature-responsive near-infrared reflective coating was fabricated based on a side-chain liquid crystal siloxane polymer using a simple wired-bar method. The cholesteric liquid crystalline polymer film showed a blue shift of the reflection band of ∼1000 nm in the IR region upon heating. The temperature-responsive change of the reflection band was reversible. Compared to that of the same mixture system in an alignment cell, the coating showed a significantly faster response. This research demonstrates an easy way to prepare a temperature-responsive IR-reflective coating that shifts its reflection to a shorter wavelength upon heating. As IR radiation of shorter wavelengths is more strongly represented in sunlight than longer wavelengths, this coating could be used to selectively reduce heating of an indoor space when the temperature is high. This is promising for the future application of smart climate control.

Applicability of radiation absorbing and non-absorbing nanoparticles in photo-thermal energy conversion: a comparative study

The radiative properties of nano-sized particles play a significant role in a widely range of industrial and engineering applications, such as chemical, electric power, industry, meteorology, biomedicine, biophysics, astronomy, combustion, fire and flame, as well as solar power plants. In the thermal applications field, nanoparticles are found to be an effective electromagnetic wave absorbers within UV–Visible wavelength range; where, short wavelength radiations include high energy photons. Because of their excellent and unique thermo-optical properties which are the basis of thermal phenomena and energy conversion, nanoparticles are used as working media in solar thermal collectors for photo-thermal energy conversion. The purpose of the present study is to investigate the applicability of absorbing (conducting) and non-absorbing (dielectric) nanoparticles in photo-thermal energy conversion. These particles are dispersed in a media to produce nanoparticle suspensions. The comparison between the radiative properties of the two nanoparticles with their suspensions is carried out. The radiative properties include scattering, absorption as well as extinction coefficients which are the most important parameters in the capture and utilization of solar energy. The contribution of particle scattering in the radiation attenuation is investigated by computing the single scattering albedo. Through the analysis of the radiative and thermal behaviour of the particulate medium, it is clear that photothermal conversion is important to not only the solar thermal systems, but also to the electricity generation and solar chemical technology, in addition to the other applications.

Quantitative Evaluation of Hard X-ray Damage to Biological Samples using EUV Ptychography

Coherent diffractive imaging (CDI) has become a standard method on a variety of synchrotron beam lines. The high brilliance short wavelength radiation from these sources can be used to reconstruct attenuation and relative phase of a sample with nanometre resolution via CDI methods. However, the interaction between the sample and high energy ionising radiation can cause degradation to sample structure. We demonstrate, using a laboratory based high harmonic generation (HHG) based extreme ultraviolet (EUV) source, imaging a sample of hippocampal neurons using the ptychography method. The significant increase in contrast of the sample in the EUV light allows identification of damage induced from exposure to 7.3 keV photons, without causing any damage to the sample itself.

Top-of-atmosphere radiative forcing affected by brown carbon in the upper troposphere

Carbonaceous aerosols affect the global radiative balance by absorbing and scattering radiation, which leads to warming or cooling of the atmosphere, respectively. Black carbon is the main light-absorbing component. A portion of the organic aerosol known as brown carbon also absorbs light. The climate sensitivity to absorbing aerosols rapidly increases with altitude, but brown carbon measurements are limited in the upper troposphere. Here we present aircraft observations of vertical aerosol distributions over the continental United States in May and June 2012 to show that light-absorbing brown carbon is prevalent in the troposphere, and absorbs more short-wavelength radiation than black carbon at altitudes between 5 and 12 km. We find that brown carbon is transported to these altitudes by deep convection, and that in-cloud heterogeneous processing may produce brown carbon. Radiative transfer calculations suggest that brown carbon accounts for about 24% of combined black and brown carbon warming effect at the tropopause. Roughly two-thirds of the estimated brown carbon forcing occurs above 5 km, although most brown carbon is found below 5 km. The highest radiative absorption occurred during an event that ingested a wildfire plume. We conclude that high-altitude brown carbon from biomass burning is an unappreciated component of climate forcing. Brown carbon absorbs light, but its climate impacts in the upper troposphere are not well known. A series of aircraft observations in the US reveals that convection lofts brown carbon to high altitudes, causing greater warming than at lower altitudes.

Serious limitations of the strong equivalence principle

It is well known that an accelerated charged particle radiates away energy. However, whether an accelerated neutral composite particle radiates away energy is unclear. We study decoherent Larmor radiation from an accelerated neutral composite object. We find that the neutral object’s long wavelength radiation is highly suppressed because radiation from different charges is canceled out. However, the neutral object radiates high energy or short wavelength radiation without any suppression. In that case, radiation from each particle can be treated independently, and it is called the decoherent radiation. We compare a hydrogen atom’s decoherent Larmor radiation with its gravitational radiation while the atom is in a circular orbit around a star. Gravitational radiation is stronger than the electromagnetic radiation if the orbital radius is larger than some critical radius. Since the decoherent radiation is related to the object’s structure, this implies that the strong equivalence principle which states that gravitational motion does not depend on an object’s constitution has severe limitations.

Liquid Water Restricts Habitability in Extreme Deserts.

Liquid water is a requirement for biochemistry, yet under some circumstances it is deleterious to life. Here, we show that liquid water reduces the upper temperature survival limit for two extremophilic photosynthetic microorganisms (Gloeocapsa and Chroococcidiopsis spp.) by greater than 40°C under hydrated conditions compared to desiccated conditions. Under hydrated conditions, thermal stress causes protein inactivation as shown by the fluorescein diacetate assay. The presence of water was also found to enhance the deleterious effects of freeze-thaw in Chroococcidiopsis sp. In the presence of water, short-wavelength UV radiation more effectively kills Gloeocapsa sp. colonies, which we hypothesize is caused by factors including the greater penetration of UV radiation into hydrated colonies compared to desiccated colonies. The data predict that deserts where maximum thermal stress or irradiation occurs in conjunction with the presence of liquid water may be less habitable to some organisms than more extreme arid deserts where organisms can dehydrate prior to being exposed to these extremes, thus minimizing thermal and radiation damage. Life in extreme deserts is poised between the deleterious effects of the presence and the lack of liquid water. Key Words: Deserts-Extremophiles-Stress-High temperatures-UV radiation-Desiccation. Astrobiology 17, 309-318.

Retention of duplicated long-wavelength opsins in mosquito lineages by positive selection and differential expression

BackgroundOpsins are light sensitive receptors associated with visual processes. Insects typically possess opsins that are stimulated by ultraviolet, short and long wavelength (LW) radiation. Six putative LW-sensitive opsins predicted in the yellow fever mosquito, Aedes aegypti and malaria mosquito, Anopheles gambiae, and eight in the southern house mosquito, Culex quinquefasciatus, suggest gene expansion in the Family Culicidae (mosquitoes) relative to other insects. Here we report the first detailed molecular and evolutionary analyses of LW opsins in three mosquito vectors, with a goal to understanding the molecular basis of opsin-mediated visual processes that could be exploited for mosquito control.ResultsTime of divergence estimates suggest that the mosquito LW opsins originated from 18 or 19 duplication events between 166.9/197.5 to 1.07/0.94 million years ago (MY) and that these likely occurred following the predicted divergence of the lineages Anophelinae and Culicinae 145–226 MY. Fitmodel analyses identified nine amino acid residues in the LW opsins that may be under positive selection. Of these, eight amino acids occur in the N and C termini and are shared among all three species, and one residue in TMIII was unique to culicine species. Alignment of 5′ non-coding regions revealed potential Conserved Non-coding Sequences (CNS) and transcription factor binding sites (TFBS) in seven pairs of LW opsin paralogs.ConclusionsOur analyses suggest opsin gene duplication and residues possibly associated with spectral tuning of LW-sensitive photoreceptors. We explore two mechanisms - positive selection and differential expression mediated by regulatory units in CNS – that may have contributed to the retention of LW opsin genes in Culicinae and Anophelinae. We discuss the evolution of mosquito LW opsins in the context of major Earth events and possible adaptation of mosquitoes to LW-dominated photo environments, and implications for mosquito control strategies based on disrupting vision-mediated behaviors.

Naturally occurring fluorescence in frogs

Fluorescence, the absorption of short-wavelength electromagnetic radiation reemitted at longer wavelengths, has been suggested to play several biological roles in metazoans. This phenomenon is uncommon in tetrapods, being restricted mostly to parrots and marine turtles. We report fluorescence in amphibians, in the tree frog Hypsiboas punctatus, showing that fluorescence in living frogs is produced by a combination of lymph and glandular emission, with pigmentary cell filtering in the skin. The chemical origin of fluorescence was traced to a class of fluorescent compounds derived from dihydroisoquinolinone, here named hyloins. We show that fluorescence contributes 18-29% of the total emerging light under twilight and nocturnal scenarios, largely enhancing brightness of the individuals and matching the sensitivity of night vision in amphibians. These results introduce an unprecedented source of pigmentation in amphibians and highlight the potential relevance of fluorescence in visual perception in terrestrial environments.

Surface Variability of Short-wavelength Radiation and Temperature on Exoplanets around M Dwarfs

Abstract It is a common practice to use 3D General Circulation Models (GCM) with spatial resolution of a few hundred kilometers to simulate the climate of Earth-like exoplanets. The enhanced albedo effect of clouds is especially important for exoplanets in the habitable zones around M dwarfs that likely have fixed substellar regions and substantial cloud coverage. Here, we carry out mesoscale model simulations with 3 km spatial resolution driven by the initial and boundary conditions in a 3D GCM and find that it could significantly underestimate the spatial variability of both the incident short-wavelength radiation and the temperature at planet surface. Our findings suggest that mesoscale models with cloud-resolving capability be considered for future studies of exoplanet climate.

Effects of beam temperature and plasma frequency on the radiation growth rate of a FEL with a laser wiggler

AbstractA linearly polarized laser pulse has been employed as a wiggler in a free-electron laser (FEL) in the presence of a plasma background for generating short wavelength radiation down to the extreme ultraviolet ray and X-ray spectral regions. Introducing plasma background in the FEL interaction region would lessen the beam energy requirement and also enhance both the beam current and the electron-bunching process. This configuration affords the possibility of scaling the device to more compact FELs and would have a higher tunability by changing the plasma density and the temperature of the electron beam. Electron trajectories have been analyzed using single-particle dynamics. The effect of plasma density on electron orbits has been investigated. A polynomial dispersion relation considering longitudinal thermal motion has been derived, by employing perturbation analysis. Numerical studies indicate that by increasing plasma density, the growth rate for groups I and II decreases, while the growth rate for group III increases. In addition, the effect of beam temperature and cyclotron frequency on the growth rate has been discussed. It has been found that by increasing the thermal velocity of the electron beam, the growth rate for groups I and III trivially decreases, while it increases for group II orbits. Besides, an increase in cyclotron frequency cause growth enhancement for group I orbits, while it present a growth decrement for group II and III orbits.

Comparison of in-situ and satellite data of surface incoming short-wavelength radiation for the Atlantic Ocean during 2004–2014

Information about short-wavelength (from 0.2 to 4 μm) heat radiation fluxes incoming to the ocean surface is available from very few observations collected by shipboard equipment and buoys and obtained from satellite data archives. Presently, the most complete archive on short-wavelength radiation fluxes is provided by geostationary Earth-orbiting satellites, such as 1G and 2G МETEOSAT (European Union), GOES (United States) and HIMAWARI (Japan), which are equipped with scanners operating in the visible and infrared (IR) ranges, which can image the Earth’s disk every 0.5 h. Additionally, the European EPS/MetOP satellites and US NOAA satellites circulating in mid-altitude circumpolar Sun-synchronous orbits and carrying AVHRR radiometers [1] can be used to obtain daily and monthly average values of incoming short-wavelength solar radiation fluxes. In the future, radiation heat flux data measured by satellites will undoubtedly play a leading role; however, today, the available data record spans only the last few decades, still lacking accuracy and consequently requiring thorough validation.

Artificial night lighting inhibits feeding in moths.

One major, yet poorly studied, change in the environment is nocturnal light pollution, which strongly alters habitats of nocturnally active species. Artificial night lighting is often considered as driving force behind rapid moth population declines in severely illuminated countries. To understand these declines, the question remains whether artificial light causes only increased mortality or also sublethal effects. We show that moths subjected to artificial night lighting spend less time feeding than moths in darkness, with the shortest time under light conditions rich in short wavelength radiation. These findings provide evidence for sublethal effects contributing to moth population declines. Because effects are strong under various types of light compared with dark conditions, the potential of spectral alterations as a conservation tool may be overestimated. Therefore, restoration and maintenance of darkness in illuminated areas is essential for reversing declines of moth populations.

Fungal tissue per se is stronger as a UV-B screen than secondary fungal extrolites in Lobaria pulmonaria

Abstract To test the hypotheses that (1) protective mycobiont tissues and/or (2) medullary UV-B-absorbing carbon-based secondary compounds (CBSCs) protect lichen photobionts against UV-B radiation, we quantified cortical UV-transmittance and ran a three-way factorial lab experiment with (1) three UV radiation regimes, (2) photobiont layers with/without a screening cortex, and (3) with natural/reduced CBSC-concentration. We used melanin-deficient Lobaria pulmonaria from shaded forests. Maximum photochemical efficiency of photosystem II ( F v/ F m) in photobionts inside thalli with natural CBSC-concentrations was not affected by any UV-regime, consistent with close to 0% measured cortical transmittance of wavelengths P P P = 0.001), mainly affecting exposed photobiont layers given short-wavelength UV radiation. Based on these findings, we conclude that the primary role of extrolites in L. pulmonaria is not to screen excess solar radiation.

Biological and material science applications of EUV and SXR nanoscale imaging systems based on double stream gas puff target laser plasma sources

Abstract In the last 30 years much effort was made in order to develop compact laser-produced plasma sources emitting short wavelength radiation, from the soft X-ray (SXR, λ = 0.1–10 nm), especially in the so-called “water window” (λ = 2.3–4.4 nm) and in the extreme ultraviolet (EUV, λ = 10–120 nm) spectral ranges. Investigations in the nanometer scale, employing short wavelengths, drive the need for developing table-top microscopes, to overpass the limitations imposed by large facilities, such as their high complexity, maintenance costs and the limited user access. In this paper we present our recent results related to nanoscale imaging using such table-top and desk-top EUV/SXR microscopes. Their construction is based on a double stream gas puff target laser plasma source. The double stream gas puff target EUV and SXR sources, coupled with Fresnel zone plates (FZPs) represent a suitable platform for microscopy experiments in transmission mode, employing SXR and EUV radiation. It represents a possible complementary technique to synchrotrons and free-electron laser facilities. The sources, which are very easy to be used by a single user, allow for efficient generation of plasma radiation with high SXR/EUV flux. Presented herein compact microscopes, based on that source, allow one to capture SXR and EUV images of various samples, with 50–60 nm half-pitch spatial resolution (corresponding to a Rayleigh resolution of 100–120 nm) and exposure time of the order of few seconds. Thus, herein, we would like to present our recent developments and progress in compact desk-top SXR/EUV microscopy employing laser plasma gas puff target sources, showing examples of acquired images and possible applications.

On using the precise sensor

In precision agriculture, the selection and use of appropriate sensors determine the type and quality of information that will feed decision-support models. A wide variety of sensors, spectral ranges, data collection and processing approaches are used, sometimes leading to confusion. Whether in transmission or reflectance mode, multispectral or hyperspectral, laboratory or field-based or even satellite-borne, in order to achieve meaningful and accurate measurements it is essential to have a clear understanding of which part of the electromagnetic spectrum the sensors relate to and how the corresponding radiation interacts with the substrate (e.g. soils, crops, livestock products). Sensors in the visible range (390-700 nm) use colour to identify certain properties of the substrate (e.g. chlorophyll and pigments in crops, organic matter contents in soil) and can be used to detect and quantify colour changes that could, in turn, be correlated with changes in those properties. Alternatively, radiation in the near (NIR, 750-2500 nm) and mid infrared (MIR, 2500-25 000 nm) interacts with the molecular bonds that constitute organic and inorganic matter and, therefore, sensors with detectors in these ranges provide different but interrelated information on the chemical composition of the substrate. Shorter wavelength radiation in the form of X-Rays (0.1-10 nm) induces fluorescence in the substrate and XRF sensors provide elemental atomic information that is highly applicable to the study of soils, sediments and fluids. At the James Hutton Institute, we have expertise in the use of all these types of sensors and are developing practical applications based on a thorough understanding of the processes involved. In this paper we provide an overview of the capabilities and applications of the different sensors used in precision agriculture, not only with a theoretical understanding, but also with an awareness of the practicalities involved.

Attosecond twisted beams from high-order harmonic generation driven by optical vortices

Optical vortices are structures of the electromagnetic field with a spiral phase ramp about a point-phase singularity, carrying orbital angular momentum (OAM). Recently, OAM has been imprinted to short-wavelength radiation through high-order harmonic generation (HHG), leading to the emission of attosecond twisted beams in the extreme-ultraviolet (XUV) regime. We explore the details of the mapping of the driving vortex to its harmonic spectrum. In particular, we show that the geometry of the harmonic vortices is convoluted, arising from the superposition of the contribution from the short and long quantum paths responsible of HHG. Finally, we show how to take advantage of transverse phase-matching to select twisted attosecond beams with different spatiotemporal properties.

Amplification of short-wavelength radiation by relativistic electron beams moving near the impedance surfaces

Amplification of short-wavelength radiation by relativistic electron beams moving near the impedance surfaces

Down-Conversion of Short-Wavelength Radiation in LBO Crystal

Comparative model analysis of the possibilities of down-conversion into the terahertz (THz) frequency range of radiation of all-solid-state femtosecond Ti:Sapphire laser systems and hybrid systems based on the same type lasers and equipped with amplifiers on XeF(C-A) and XeCl(C-A) molecules of excimer gases with harmonic generators on nonlinear LBO crystals is performed. It is established that when the crystal is cooled to a temperature of 80 K, the coefficient of optical losses in the frequency range from 0.2 to 1.5 THz linearly decreases in the direction of the X axis by 5–6 times down to 0.1–0.2 cm–1. It is shown that the use of hybrid laser systems as pumping sources will allow the power of generated THz pulses to be increased from 3.5 to 20 times.