Mean Wavelength Research Articles

The effect of diagenesis and acetolysis on the preservation of morphology and ultrastructural features of pollen

Pollen morphology on its own and in conjunction with other characteristics has elucidated the origin and evolution of various plant groups. Previous studies of fossil pollen rarely discuss the effects of diagenesis and sample preparation on pollen characteristics, i.e., variability in staining, pollen morphology, and pollen wall ultrastructural characteristics. This paper examines the effect of acetolysis on reflectance and spectral epi-fluorescence measurements. Based on empirical studies, different species under similar experimental conditions display different reflectance values, indicating individual species respond differently to similar post-depositional thermal events. The quantitative pollen fluorescence spectra showed significant variability, but there is an overall increase in the mean wavelength of maximum emission with acetolysis. Increases in these spectral parameters are used to infer thermal maturation and diagenetic pathways in fossil pollen. The paper also discusses observations made on fossil pollen of a known thermal maturity using Pearson's Pollen/Spore Color Standard. Assessment of pollen thermal maturity using this color standard can be an indicator of the quality of morphological and ultrastructural information that can be extracted from fossil pollen. Increasing thermal maturity of pollen may have an effect on staining variability. Based on observations, staining for brightfield or electron microscopy in fossil pollen, although useful for improving contrast in the specimen, must be used with caution when interpreting pollen wall structure. Although single fossil pollen investigations are useful, replication of these studies on similar or the same specimens from the same locality or various localities will collectively provide more information for elucidation of the morphology and ultrastructure of the once living pollen, and is helpful in sorting out characteristics that may be artifacts from post-depositional diagenesis.

Influence of temperature on detectable minimum rotation rate in i-FOGs using Er-doped SFSs

Abstract In this study, an interferometric fiber optic gyroscope (I-FOG) model exploiting the double-pass backward (DPB) erbium-doped superfluorescent fiber source (SFS) with both thin-film filter (TFF) and fiber bragg grating (FBG) reflectors has been constructed and the effects of temperature variations on mean wavelength and detectable minimum rotation rate (DMRR) have been theoretically analyzed. the simulations corresponding with the relations between these parameters for temperature variations in the range of −60 °C to + 90 °C, have been performed using Matlab 2021b. DMRR variations have been found as 6.01 ppm/K and 3.83 ppm/K for the system with TFF, whilst they are 15.31 ppm/K and 1.58 ppm/K for the system with FBG.

Could Curcumin hydrogel for photodynamic therapy fight against SARS-CoV-2?

A traditional Chinese medicine “Curcumin” has been used as a photosensitizer in the application of photodynamic therapy such a long time. However, it has significant limitations, including poor “solubility” and “absorbtivity”. “Hydrogel” is being used to overcome these problems, which enhance the biodegradability and biocompatibility of curcumin. This present article discusses the background, research progress, and clinical study to describe the possibility of curcumin hydrogel for photodynamic therapy fight against SARS-CoV-2. Based on the literature review finding, curcumin as a photosensitizer uses a microcatheter to incorporate the hydrogel systemically or locally into the lungs through the pulmonary artery to combat SARS-CoV-2. It is extracorporeal illumination for photodynamic therapy, which exposure to blue light with a mean wavelength of 450 nm is a much safe and limited depth of photodynamic therapy treatment. Thus, curcumin incorporated with the hydrogel is a suitable candidate used for the photodynamic treatment of SARS-CoV-2, cancer, wound healing, and bacterial infection.

Abnormal neurotransmission of GABA and serotonin in Caenorhabditis elegans induced by Fumonisin B1

Fumonisin B1 (FB1) is a neurodegenerative mycotoxin synthesized by Fusarium spp., but the potential neurobehavioral toxicity effects in organisms have not been characterized clearly. Caenorhabditis elegans (C. elegans) has emerged as a promising model organism for neurotoxicological studies due to characteristics such as well-functioning nervous system and rich behavioral phenotypes. To investigate whether FB1 has neurobehavioral toxicity effects on C. elegans, the motor behavior, neuronal structure, neurotransmitter content, and gene expression related with neurotransmission of C. elegans were determined after exposed to 20–200 μg/mL FB1 for 24 h and 48 h, respectively. Results showed that FB1 caused behavioral defects, including body bends, head thrashes, crawling distance, mean speed, mean amplitude, mean wavelength, foraging behavior, and chemotaxis learning ability in a dose-, and time-dependent manner. In addition, when C. elegans was exposed to FB1 at a concentration of 200 μg/mL for 24 h and above 100 μg/mL for 48 h, the GABAergic and serotonergic neurons were damaged, but no effect on dopaminergic, glutamatergic, and cholinergic neurons. The relative content of GABA and serotonin decreased significantly. Furthermore, abnormal expression of mRNA levels associated with GABA and serotonin were found in nematodes treated with FB1, such as unc-30, unc-47, unc-49, exp-1, mod-5, cat-1, and tph-1. The neurobehavioral toxicity effect of FB1 may be mediated by abnormal neurotransmission of GABA and serotonin. This study provides useful information for understanding the neurotoxicity of FB1.

Prediction of the tribological characteristics of non‐Gaussian rough surfaces during sliding wear in mixed lubrication

AbstractIn mixed lubrication, material wear is inevitably caused due to solid contact. Simultaneously, the surface morphology after wear will affects the lubrication performance. To understand this coupling process, virtual surface reconstruction technology and mixed lubrication sliding wear model were applied to predict the evolution of wear characteristics and lubrication characteristics during wear in this study. The effects of the roughness root mean square (RMS), roughness direction and wavelength ratio on the contact area ratio, the contact load ratio, accumulated wear, film thickness and the friction coefficient were analysed. The results indicated that the contact area ratio and the contact load ratio and the friction coefficient decreased and average film thickness increased with the increase in the number of the wear cycles. In addition, a surface with low‐roughness RMS, longitudinal roughness texture and high‐wavelength ratio is suitable for improving lubrication performance and reducing wear.

Polarization stabilization of the mean wavelength of erbium-doped super fluorescent fiber optic sources

We investigate the influence of polarization on the stability of a single-pass fiber super fluorescent light source (SFS) operating under the forward or reverse setup. The measurement of amplified spontaneous emission (ASE) spectra obtained using different values for the power and state of polarization (SOP) of the optical pump (980 nm) is the basis of the analysis. The mean wavelength was the stability evaluation criterion used for comparing the forward and backward SFS emission. The results indicate that both super fluorescent sources become insensitive to the polarization state when the pump power reaches a saturated absorption condition. The influence of the SFS spectral range is also analyzed, defining four spectral bands; Ctot band (1520–1570 nm), C band (1530–1560 nm), C+ band (1520–1540 nm), and C− band (1540–1560 nm). We show that the stability of the SFS improves by discriminating one of the two peaks of the ASE emission spectrum, reaching the performance required for inertial grade sensors.

Database of extreme waves generated during the passage of a cold front in Rio Grande do Sul coast, southern Brazil

This datapaper supports the use of a database generated from wavefield simulations with the WAVEWATCH III model in waters off the coast of Rio Grande do Sul in the South Atlantic Ocean. In the WAVEWATCH III simulations, three domains are generated as a part of a numerical experiment to set up the best configuration. This database includes all input and output files for the two best-fit simulations. Bathymetry and wind files at 10 m above the surface are available as input files. The period of simulation and non-stationary wind data input corresponds to March 22-28, 2016. The date was chosen because it is related to the passage of a cold front through the area of interest. The different parameterizations used and with which good results were obtained in the simulations with the model are also described. The WAVEWATCH III output files contain the spatial and temporal distribution of the wavefield in the area of interest, as well as the outputs for point locations consistent with the location of on-site records. For the two best-fit domains, the following variables were obtained: mean wind speed (m s-1), sea-air temperature difference (°C), wave height (m), mean wavelength (m), mean wave period (s), mean wave direction (degrees), mean directional propagation (degrees) and friction velocity (m s-1). All these variables are provided in NetCDF format and will serve as a reference for future wave modeling work in the region, and the results will be able to be compared with those obtained in the database.

Flow patterns of Jupiter's south polar region

Previous studies of Jupiter's wind patterns revealed the southernmost two prograde jets at 58°S and 64°S (planetocentric), which we designate as the S5 and S6 jets, respectively, but the jets and the wind patterns further poleward were not well defined. The Juno mission has provided the first opportunity to study the South Polar Region (SPR). Here we use images from Juno's camera, JunoCam, to characterize these jets and the wind patterns further south. We measure the main wind systems using JunoCam images taken up to two hours apart. The S5 jet coincides with a slightly sinuous boundary in methane-band images. The S6 jet is faster, broader and highly undulating in latitude, generally coinciding with the sinuous edge of the methane-bright South Polar Hood, whose wave pattern is often regular with a mean wavelength of 25.5° (±2.6°) longitude. Peak wind speeds along the S6 jet range from 42 (±12) to 49 (±11) m/s, faster than previously recognized. Poleward of the S6 jet, at ~65–70°S, there is an irregular belt of chaotic cyclonic regions termed folded filamentary regions (FFRs), with several small anticyclonic white ovals (AWOs) on or near its southern edge. Some of these FFRs appear to be extending northeast into the S6 jet. More FFRs are scattered from ~70 to 80°S. Wind speeds in the FFRs are generally ~20–60 m/s, comparable to lower-latitude cyclonic circulations. We also generate semi-quantitative maps of local vorticity, and thence, mean zonal vorticity profiles as a function of latitude. These confirm the S6 jet as sinuous and the southernmost belt of FFRs as a stable belt. Further south, there is usually a weak cyclonic vorticity maximum near 78°S, which probably represents irregular structures such as FFRs. Supplementary ground-based images, spaced by up to 4 days, show westward drifts for the ~65–70°S belt, with a mean of ~ + 0.9°/day in System III longitude. AWOs can also be tracked, for months or even years. They drift westward with a uniform speed of +0.8°/day between 69.5 and 72.4°S, but towards higher latitudes, up to 76°S, they show a steep latitudinal gradient to faster (eastward) speeds, comparable to those measured around the south polar pentagon of circumpolar cyclones at ~80°S. Overall, the ~65–70°S belt and associated AWOs show dynamical behaviour similar to lower latitudes. Further south, there are no rapid continuous jets, but the loose enhancement of cyclonic structures near 78°S suggests a trace of zonal structure extending almost as far as the polar pentagon.

I3T: Intensity Interferometry Imaging Telescope

ABSTRACT We propose a new approach, based on the Hanbury Brown and Twiss intensity interferometry, to transform a Cherenkov telescope to its equivalent optical telescope. We show that, based on the use of photonics components borrowed from quantum-optical applications, we can recover spatial details of the observed source down to the diffraction limit of the Cherenkov telescope, set by its diameter at the mean wavelength of observation. For this, we propose to apply aperture synthesis techniques from pairwise and triple correlation of sub-pupil intensities, in order to reconstruct the image of a celestial source from its Fourier moduli and phase information, despite atmospheric turbulence. We examine the sensitivity of the method, i.e. limiting magnitude, and its implementation on existing or future high energy arrays of Cherenkov telescopes. We show that despite its poor optical quality compared to extremely large optical telescopes under construction, a Cherenkov telescope can provide diffraction limited imaging of celestial sources, in particular at the visible, down to violet wavelengths.

Numerical continuation method for large-amplitude steady water waves on depth-varying currents in flows with fixed mean water depth

A numerical method is proposed for computation of large amplitude water waves interacting with depth varying currents. The proposed method is developed for fixed mean-depth of water for which a theoretical formulation has recently been introduced in the literature Henry (2013b, 2013c) but no numerical studies have been performed yet. The proposed method relies on a numerical continuation approach for computing large amplitude waves bifurcating from the steady laminar flows. This study hence is on the numerical continuation method for computing two-dimensional (2D) large-amplitude steady water waves on rotational flow with an arbitrary current profile, based on an emerging formulation of the problem. For given mean water depth, current profile, and wave length, the method is able to generate a group of waves from the laminar flow solution to the limiting wave of the largest wave height. Due to the normalization effect in the formulation, the computational domain is fixed regardless of the wave length and water depth, allowing for efficient computation even when dealing with long waves in deep water. The method is first applied to study non-linear wave-current interactions in ocean engineering demonstrating its potential in capturing the wave period changes with increasing wave amplitude in the presence of current. Furthermore, wave characteristics are investigated for cases of constant and discontinuous vorticity, revealing some interesting features. In particular, for waves on linear shear flows, the surface profiles of the waves with the largest amplitude for a range of the vorticity values tend to pass through two fixed points in the 2D plane, and this characteristic seems to be invariant of the water depth.

Grain Alignment and Disruption by Radiative Torques in Dense Molecular Clouds and Implication for Polarization Holes

Abstract Dust polarization induced by aligned grains is widely used to study magnetic fields in various astrophysical environments. However, the question of to what optical depth grain alignment still exists in a dense molecular cloud (MC) is unclear. In this paper, we derive analytical formulae for the minimum size of aligned grains (a align) and rotational disruption (a disr) by RAdiative Torques (RATs) as a function of the local physical parameters within MCs. We first find the analytical approximations for the radiation strength and mean wavelength of the attenuated radiation field in a dense MC with and without embedded stars, and then derive analytical formulae for a align and a disr as functions of the visual extinction A V and gas density. We find that, within a starless core of density , grains of size can be aligned at A V ∼ 5 by RATs, whereas micron-sized grains can still be aligned at . The increase in a align with A V can explain the presence of polarization holes observed toward starless cores. For MCs with an embedded protostar, the efficiency of both alignment and rotational disruption increases toward the protostar due to the increasing radiation strength. Such a disruption effect results in the decrease of the polarization degree with A V or emission intensity, reproducing the popular polarization holes observed toward the location of protostars. Finally, we derive the formula for the maximum A V where grain alignment still exists in a starless core, and we discuss its potential for constraining grain growth.

Математическое моделирование волнового режима бухты Ай-Тодор

Investigation of wave regime of coastal water areas is practically important for safe shipping, constructing and using of coastal infrastructure objects. At the present paper statistical characteristics and space distribution of parameters of wind waves in the Ay-Todor Bay region placed on the Crimea South Coast of the Black Sea are obtained on the basis of mathematical simulation. Analysis of the wind wave parameters for the year diapason of 1979–2017 has shown that waves running from the east and having 0.5 m heights and 3.0–3.5 s mean periods are the most repeatable. The most durable storms are formed by waves coming from East–South-South-West sector in the period from December to January. The multiannual calm duration is equal to ~11 days. Estimation of extremal characteristics (height, period and length) of wind waves of different probability, which possible one time in a year, 5, 10, 25, 50 and 100 years are made. For the storm probable one time in 25 years the mean wave height near the boundary of the Ay-Todor Bay is equal to 4.5 m. For this storm the wave height of 1% probability reaches 9.6 m. For the directions of winds of 4 % regime probability which causes the most dangerous waves calculations of wave characteristics with high space resolution (~1.5 m) are carried out by using of SWAN model and nested grid technology. Fields of significant wave height, mean wave length, bottom wave orbital velocities and space distribution of wave breaking zones are analyzed. It is found that most intensive waves are generated by wind having south-east, east and south directions. Maximal bottom orbital velocities of wave current reaches of 2.5–3.5 m/s and occurs along the coast till 10 m depth. Model calculation of wave currents by using of SWASH model allowed obtained presence in the coastal zone near beach of local cyclonic eddy, which transport suspended sediments along its south edge from beach towards the sea.

Underlying Subwavelength Aperture Architecture Drives the Optical Properties of Microcavity Surface Plasmon Resonance Sensors.

Microcavity surface plasmon resonance sensors (MSPRSs) develop out of the classic surface plasmon resonance technologies and aim at producing novel lab-on-a-chip devices. MSPRSs generate a series of spectral resonances sensitive to minute changes in the refractive index. Related sensitivity studies and biosensing applications are published elsewhere. The goal of this work is to test the hypothesis that MSPRS resonances are standing surface plasmon waves excited at the surface of the sensor that decay back into propagating photons. Their optical properties (mean wavelength, peak width, and peak intensity) appear highly dependent on the internal morphology of the sensor and the underlying subwavelength aperture architecture in particular. Numerous optical experiments were designed to investigate trends that confirm this hypothesis. An extensive study of prior works was supportive of our findings and interpretations. A complete understanding of those mechanisms and parameters driving the formations of the MSPRS resonances would allow further improvement in sensor sensitivity, reliability, and manufacturability.

Quantum black holes in bootstrapped Newtonian gravity

We analyse the classical configurations of a bootstrapped Newtonian potential generated by homogeneous spherically symmetric sources in terms of a quantum coherent state. We first compute how the mass and mean wavelength of these solutions scale in terms of the number of quanta in the coherent state. We then note that the classical relation between the ADM mass and the proper mass of the source naturally gives rise to a Generalised Uncertainty Principle for the size of the gravitational radius in the quantum theory. Consistency of the mass and wavelength scalings with this GUP requires the compactness remains at most of order one even for black holes, and the corpuscular predictions are thus recovered, with the quantised horizon area expressed in terms of the number of quanta in the coherent state. Our findings could be useful for analysing the classicalization of gravity in the presence of matter and the avoidance of singularities in the gravitational collapse of compact sources.

Low-Frequency Dynamics of Flow over a Backward-Facing Step

The low-frequency () dynamics of turbulent flow () downstream of a backward-facing step are examined by low-pass filtering the velocity fields from a long run-time large-eddy simulation. The low-frequency behaviors were found to set the location of streamwise reattachment. Examination of the instantaneous three-component velocity fields showed regions of flow where the streamwise velocity was momentarily driven all the way back to the step face. After the flow reaches the step, it is then directed along the step face in the spanwise direction, resulting in large regions of wall-normal vorticity . These large regions of vorticity are opposed by smaller regions of counter-rotating flow offset in the spanwise direction and were responsible for the spanwise variation of the reattattachment. The low-pass filtered streamwise velocity fields just above the lower wall showed significant spanwise oscillations with a mean wavelength of the streamwise low-pass filtered reattachment position of , consistent with previous studies at different Reynolds and Mach numbers. As the step geometry is homogeneous in the spanwise direction, this shows that this behavior is not the result of wall or edge effects, which is a conclusion that cannot easily be drawn from experimental studies with limited step-height-to-width ratios.

High thermal-stability Er-doped superfluorescent fiber source with a vertical cleaved fiber tail

Abstract Mean wavelength stability, a key indicator for evaluating the dynamic performance of Er-doped superfluorescent fiber source (ED-SFS) and high-precision fiber optic gyroscope (FOG), shows high sensitivity to environmental temperature fluctuations. In this paper, a thermally-stable ED-SFS in a one-stage backward configuration is proposed by incorporating a vertical cleaved fiber tail which acts as a Fresnel reflector. Our proposed method demonstrates a mean wavelength stability of 150 ppm and a scale factor error of 702 ppm. Comparing with alternative techniques such as Faraday rotator mirror (FRM) or fiber mirror (FM) over a 100 °C range (−40 °C to +60 °C), the wavelength stability and scale factor error are 105~120 ppm and 230~400 ppm less, respectively. The proposed ED-SFS has a spectral width (FWHM) of 37.682 nm and 10.42 mW output power, which satisfies the requirements of high-precision FOG.

Giant sand waves on the Taiwan Banks, southern Taiwan Strait: Distribution, morphometric relationships, and hydrologic influence factors in a tide-dominated environment

Giant sand waves (heights >10 m) are widely developed on the Taiwan Banks, the distribution pattern, morphotypes and morphometric relationships of which have not yet been fully clarified. Based on multi-beam bathymetric swath data covering 780 line km of survey track, giant sand waves with heights up to 22.5 m and wavelengths up to 2115 m have been recorded. The relationship between height (H) and wavelength (L) of the complete data set follows the regression trend of Hmean = 0.0625 L0.8152 (r = 0.94), which is in good general agreement with a previously determined average global trend of Hmean = 0.0677 L0.8098. This global trend did not include any data from the China seas. The giant sand waves have been grouped into four morphotypes, namely double-crested, symmetric, symmetric-asymmetric and asymmetric forms. The individual bedform morphotypes and their spatial distribution were investigated in relation to water depth, textural characteristics of the sediment, and the hydrodynamic conditions recorded by several 25-hour repeated ship-based current observations. The relationship between mean water depth (D) and mean sand wave height (H) and mean wavelength (L) on the Taiwan Banks are Hmean = 0.29D (r = 0.35) and Lmean = 36D (r = 0.42), respectively. With increasing water depth, the shape of the sand wave becomes gentler. It is found that the coarser sediment (median grain size of 0.51–0.54 mm) and stronger flow in the present study may contribute to the larger H/D and L/D ratios at the given water depths than other sand wave fields. And flows of varying from equal to unequal northerly and southerly components correspond with sand waves from symmetrical to asymmetrical forms. A decrease in velocity and a veering in direction of flows have been observed over the giant sand waves, indicating the interaction between large bedforms and the near-bed water layer in the study area.

X-ray diffraction at the National Ignition Facility.

We report details of an experimental platform implemented at the National Ignition Facility to obtain in situ powder diffraction data from solids dynamically compressed to extreme pressures. Thin samples are sandwiched between tamper layers and ramp compressed using a gradual increase in the drive-laser irradiance. Pressure history in the sample is determined using high-precision velocimetry measurements. Up to two independently timed pulses of x rays are produced at or near the time of peak pressure by laser illumination of thin metal foils. The quasi-monochromatic x-ray pulses have a mean wavelength selectable between 0.6 Å and 1.9 Å depending on the foil material. The diffracted signal is recorded on image plates with a typical 2θ x-ray scattering angle uncertainty of about 0.2° and resolution of about 1°. Analytic expressions are reported for systematic corrections to 2θ due to finite pinhole size and sample offset. A new variant of a nonlinear background subtraction algorithm is described, which has been used to observe diffraction lines at signal-to-background ratios as low as a few percent. Variations in system response over the detector area are compensated in order to obtain accurate line intensities; this system response calculation includes a new analytic approximation for image-plate sensitivity as a function of photon energy and incident angle. This experimental platform has been used up to 2 TPa (20 Mbar) to determine the crystal structure, measure the density, and evaluate the strain-induced texturing of a variety of compressed samples spanning periods 2-7 on the periodic table.

Electromagnetic field expectations as measures of photon localization

The questions of whether a photon can be localized in an arbitrarily small volume and what is the allowable strength of that localization (the decrease with distance of the functional form) are questions of current interest. We propose a measure of localization for the single photon that is the expectation values of the electromagnetic field strength components in a coherent wavepacket state of mean photon number unity. As such, we deal with real quantities that have a physical meaning rather than complex amplitudes. It is seen that the real parts of complex amplitudes proposed previously as measures of localization are equal to our field expectations. With this measure, we examine two test states. The first has a well-resolved momentum. The field expectations show Gaussian (quadratic exponential) localization in all directions, although the localization length scale is much larger than the mean wavelength. For the other test state, with a spherically symmetric momentum distribution, we find almost exponential localization in all directions at t = 0. The profiles are scale invariant, so choosing the momentum width very large would make the localization length arbitrarily small. We conclude that there is no lower bound on the localization length scale of a photon as determined by this measure.

Two-parameter Hong-Ou-Mandel dip

A modification of the standard Hong-Ou-Mandel interferometer is proposed which allows one to replicate the celebrated coincidence dip in the case of two-independent delay parameters. In the ideal case where such delays are sufficiently stable with respect to the mean wavelength of the pump source, properly symmetrized input bi-photon states allow one to pinpoint their values through the identification of a zero in the coincidence counts, a feature that cannot be simulated by semiclassical inputs having the same spectral properties. Besides, in the presence of fluctuating parameters the zero in the coincidences is washed away: still the bi-photon state permits to recover the values of parameters with a visibility which is higher than the one allowed by semiclassical sources. The detrimental role of loss and dispersion is also analyzed and an application in the context of quantum positioning is presented.