Intensity Distribution Research Articles

Statistics of the Interplanetary Magnetic Field from 0.1 to 30 au. I. Distribution Character

Abstract This study investigates the directional and intensity distributions of the interplanetary magnetic field (IMF) across a heliocentric distance range of approximately 0.1–30 au. Measurements from multiple spacecraft reveal that these distributions align closely with the Parker spiral configuration in general. Nevertheless, the deviation from the model is significant and regular. To analyze these deviations, we organized the IMF observations based on the orientation and intensity predicted by the Parker model. The average angular deviation from the Parker spiral increases between 0.1 and 1 au, stabilizing from 1 to 30 au. The magnetic field components perpendicular to the Parker spiral are more likely to lay in the latitudinal and longitudinal directions during the solar maximum and minimum, respectively. The normalized intensity distribution follows a log-normal distribution, with its broadening positively correlated with increasing heliocentric distance. These characteristics cannot be fully attributed to Alfvénic fluctuations or the nonradial component near the potential field source surface. Instead, interactions of flux tubes in the outer heliosphere play a significant role in shaping the IMF. Our results provide a comprehensive assessment of the frequency with which planets encounter non-Parker upstream conditions.

Azimuthally Spliced Power-Exponential Phase Modulation for Focal Spot Shaping of Circular Airy Beams

Circular airy beam (CAB) is a kind of new structured light with non-diffracting, self-focusing, and self-healing properties. Due to its wide applications, recently, numerous researchers have used various methods to modulate this kind of beam. We theoretically verify and experimentally demonstrate the azimuthal modulation method to shapes the focal spot of the CAB by modulating the CAB with the azimuthally spliced power-exponential phase. The results show that after modulating by an azimuthally spliced power-exponential phase, multi-focal spots can be generated on the self-focusing focal plane of the modulated CAB, and the number of the focal spots can be precisely controlled by controlling the number of segments of the spliced power-exponential phase. The situations of generating three, four, and five focal spots can be achieved via appropriate azimuthally spliced power-exponential phase modulation. We also calculate the intensity distribution, energy flow density, angular momentum density, and optical force of the modulated beam after tight focusing. The results illustrate the theoretical possibility of stable multiparticle trapping by the modulated beam. Our results pave the way for on-demand shaping of the self-focusing focus of the CAB, which will facilitate related applications, such as CAB based multi-particle trapping.

Photonics-based Bessel beam launcher with an air-filled core and cylindrical Bragg gratings in the cladding

In this study, we develop a photonics-based Bessel launcher characterized by a hollow-core cylindrical waveguide surrounded by Bragg gratings composed of concentric silicon rings, each 375 nm thick. The metasurface is constructed on a 5 µm high silicon cylindrical substrate. This configuration effectively generates a Bessel beam at the commonly used telecom infrared optical wavelength of 1.55 µm. We explore three variations of this optical antenna, featuring 3-, 6-, 16-, and 32-ring arrays, respectively. We compare the results with the geometrical optics approach as well as the Rayleigh hypothesis. The performance of the optical antenna configuration is assessed through simulated far-field polar plots and z-directed intensity distributions up to a non-diffracting range (NDR) of 1 mm using CST Microwave Studio and Lumerical FDTD INTERCONNECT. These simulations reveal that the optical antenna gain of the launcher in the far field varies from 20 to 26 dBi as the number of concentric rings increases from 6 to 32. We report the S11 reflection coefficient of −33dB and the radiation efficiency of 0.01 dB. To independently verify the angular spectrum of the antenna, we employ dyadic Green’s functions, orthogonal vector wave functions, and Bloch’s theorem in MATLAB, demonstrating exceptional coupling of the Gaussian beam into the photonic device with a radiation efficiency of 99%.

Crystallographic properties of the HgCdTe layers grown by MBE on CdZnTe(211)B substrates

A review of the specificity of the growth Hg1-xCdxTe layers by molecular beam epitaxy (MBE) and results of experimental studies of several Hg1-xCdxTe layers grown on CdyZn1-yTe (CZT) substrates are presented. It is well known that the performance of Hg1-xCdxTe -based detectors strongly depends on the substrate material and its orientation. CZT substrates are among the most commonly used due to their very good lattice match with Hg1-xCdxTe absorber material with different Cd content. In the present work, the authors focused on optimizing the MBE growth parameters in order to obtain the best possible crystalline quality of Hg1-xCdxTe layers grown on CZT substrates with (211)B orientation, in particular in terms of minimizing the number of defects. Experimental results of the selected structures showed that the obtained undoped Hg1-xCdxTe layers of different x have high crystallographic and optical quality, as well as good surface morphology. In particular, high-resolution X-ray diffraction (HRXRD) measurements and their analysis showed that the best structure has a full width at half maximum of rocking curve (FWHMRC) as low as 21.5 arcsec, and that the intensity distribution of diffraction peaks does not indicate the influence of mosaicisity and dislocation density.

Fabrication and Simulation of Optical Shaping Diffuser to Control Light Patterns

This study utilizes a 532 nm picosecond laser micromachining technique on Schott-B270 glass to fabricate micro-lens array (MLA) with optimized curvature and minimal surface roughness, aimed at achieving an optical shaping diffuser. The research demonstrates a two-step fabrication process that combines picosecond laser processing with wet etching, significantly enhancing optical diffusion. Square-shaped micro-lenses with diffusion angles ranging from 29° to 62° were successfully created, along with hexagonal and rectangular shapes. Optical simulations using LightTools, which employed built-in Bezier curves to design micro-lens parameters, analyzed the impact of micro-lens arrangements on light patterns. The simulations indicated that varying the spacing and overlap ratio of the micro-lenses influenced light intensity distribution, achieving uniform light patterns with intensity variations of less than 10%. Experimental validation through optical measurements confirmed that the fabricated MLA produced well-defined light patterns, demonstrating their effectiveness for various optical applications. This work contributes to advancing the understanding of micro-lens fabrication techniques and their applications in enhancing light distribution.

Which Training Intensity Distribution Intervention will Produce the Greatest Improvements in Maximal Oxygen Uptake and Time-Trial Performance in Endurance Athletes? A Systematic Review and Network Meta-analysis of Individual Participant Data.

Endurance athletes tend to accumulate large training volumes, the majority of which are performed at a low intensity and a smaller portion at moderate and high intensity. However, different training intensity distributions (TID) are employed to maximize physiological and performance adaptations. The objective of this study was to conduct a systematic review and network meta-analysis of individual participant data to compare the effect of different TID models on maximal oxygen uptake (VO2max) and time-trial (TT) performance in endurance-trained athletes. Studies were included if: (1) they were published in peer reviewed academic journals, (2) they were in English, (3) they were experimental or quasi-experimental studies, (4) they included trained endurance athletes, (5) they compared a polarized (POL) TID intervention to a comparator group that utilized a different TID model, (6) the duration in each intensity domain could be quantified, and (7) they reported VO2max or TT performance. Medline and SPORTDiscus were searched from inception until 11 February 2024. We included 13 studies with 348 (n = 296 male, n = 52 female) recreational (n = 150) and competitive (n = 198) endurance athletes. Mean age ranged from 17.6 to 41.5years and VO2max ranged from 46.6 to 68.3mL·kg-1·min-1, across studies respectively. Based on the time in heart rate zone approach, there was no difference in VO2max (SMD=-0.06, p=0.68) or TT performance (SMD=-0.05, p=0.34) between POL and pyramidal (PYR) interventions. There were no statistically significant differences between POL and any of the other TID interventions. Subgroup analysis showed a statistically significant difference in the response of VO2max between recreational and competitive athletes for POL and PYR (SMD=-0.63, p<0.05). Competitive athletes may have greater improvements to VO2max with POL, while recreational athletes may improve more with a PYR TID. Our results indicate that the adaptations to VO2max following different TID interventions are dependent on performance level. Athletes at a more competitive level may benefit from a POL TID intervention and recreational athletes from a PYR TID intervention.

Twist- and cross-phase-modulated Laguerre-Gaussian correlated Schell-model beam and its radiation forces

In this paper, we introduce what we believe to be a novel partially coherent beam with a nonconventional correlation function, named the twist- and cross-phase-modulated Laguerre-Gaussian correlated Schell-model (TCPM-LGSM) beam, which carries both twist and cross phase. The propagation properties of the TCPM-LGSM beam have been investigated in detail. Our results indicate that both the twist phase and cross phase hinder the evolution of the beam’s intensity distribution from a Gaussian to a hollow profile due to the correlation structure. Additionally, when the beam simultaneously carries both phases, it forms an intensity distribution with two intensity peaks in the focal plane. Furthermore, the twist phase and cross phase can improve the beam’s ability to maintain its distribution of the spectral degree of coherence (SDOC) in the far field. Under the combined influence of phases, although the distribution of the SDOC changes, it significantly enhances the ability to measure the order of the correlation structures with higher orders. Moreover, we studied the orbital angular momentum (OAM) distribution of the TCPM-LGSM beam and found that, although the correlation structure itself does not carry OAM, it substantially alters the beam’s OAM distribution when beam carries the twist and cross phase. Finally, we explored the application of the proposed beam in particle trapping. By modulating the beam’s source parameters, particles can be trapped at the ring, the center, or at the two intensity peaks, respectively. This work provides valuable theoretical guidance for information transfer and particle trapping.

Spherical harmonics texture extraction for versatile analysis of biological objects.

The characterization of phenotypes in cells or organisms from microscopy data largely depends on differences in the spatial distribution of image intensity. Multiple methods exist for quantifying the intensity distribution - or image texture - across objects in natural images. However, many of these texture extraction methods do not directly adapt to 3D microscopy data. Here, we present Spherical Texture extraction, which measures the variance in intensity per angular wavelength by calculating the Spherical Harmonics or Fourier power spectrum of a spherical or circular projection of the angular mean intensity of the object. This method provides a 20-value characterization that quantifies the scale of features in the spherical projection of the intensity distribution, giving a different signal if the intensity is, for example, clustered in parts of the volume or spread across the entire volume. We apply this method to different systems and demonstrate its ability to describe various biological problems through feature extraction. The Spherical Texture extraction characterizes biologically defined gene expression patterns in Drosophila melanogaster embryos, giving a quantitative read-out for pattern formation. Our method can also quantify morphological differences in Caenorhabditis elegans germline nuclei, which lack a predefined pattern. We show that the classification of germline nuclei using their Spherical Texture outperforms a convolutional neural net when training data is limited. Additionally, we use a similar pipeline on 2D cell migration data to extract polarization direction, quantifying the alignment of fluorescent markers to the migration direction. We implemented the Spherical Texture method as a plugin in ilastik to provide a parameter-free and data-agnostic application to any segmented 3D or 2D dataset. Additionally, this technique can also be applied through a Python package to provide extra feature extraction for any object classification pipeline or downstream analysis.

Dynamic simulation of breast behaviour during different activities based on finite element modelling of multiple components of breast

This study presents an advanced dynamic finite element (FE) model of multiple components of the breast to examine the biomechanical impact of different types of physical activities and activity intensity on the breast tissues. Using 4D scanning and motion capture technologies, dynamic data are collected during different activities. The accuracy of the FE model is verified based on relative mean absolute error (RMAE), and optimal material parameters are identified by using a validated stepwise grid search method. The comparative analysis reveals that jumping rope generates the highest stress on the breast components, followed by high knee skipping but running exerts the least amount of stress. A positive correlation between activity intensity and stress is observed for running and jumping rope, while high knee skipping shows a peak in stress after a certain threshold. The magnitude of the stress distribution and effect of activity intensity on the stress experienced by the breast internal components are in ascending order: the glandular tissues, pectoralis major muscles, adipose tissues, and Cooper’s ligaments, thus highlighting the different biomechanical response of these breast components to dynamic stress. The insights from this study have significant implications for sports bra design, rehabilitation protocols, and exercise customisation with the aim to reduce the risk of injury during breast motion.

Near-field luminous intensity distribution measurement with ex-situ error correction

Near-field luminous intensity distribution measurement with ex-situ error correction

Numerical investigation of infrared imaging of multi-UAV formation under cloud and rain weather conditions

Infrared imaging is essential for detecting multiple unmanned aerial vehicle (UAV) targets detection to capture flight altitude and behavior. This study focused on a typical stealth UAV formation with a flying-wing configuration. Considering the attenuation effects of clouds and rain on the infrared spectrum, a ground-based infrared imaging algorithm was developed. Infrared radiation imaging was conducted using the apparent ray tracing method and mesh clipping technology. The infrared radiation intensity distribution of the UAV formation target within the 8.0–12.0 μm band was calculated, and infrared thermal images incorporating the occlusion effect were obtained. The results showed that the radiance of the multi-UAV formation was approximately 8.0 × 10−5 W/Sr, which was 103–104 orders of magnitude lower than that under standard atmospheric conditions under cloudy weather conditions. The infrared radiance was approximately 1.7 × 10−5 W/Sr, which was 104–105 lower than that under standard atmospheric conditions under rainy weather conditions.

Dynamical imprints on precipitation cluster statistics across a hierarchy of high-resolution simulations

Abstract. Tropical precipitation cluster area and intensity distributions follow power laws, but the physical processes responsible for this macroscopic behavior remain unknown. We analyze global simulations at 10 km horizontal resolution that are configured to have drastically varying degrees of realism, ranging from global radiative–convective equilibrium to fully realistic atmospheric simulations, to investigate how dynamics influence precipitation statistics. We find the presence of stirring and large-scale vertical overturning, as associated with substantial planetary- and synoptic-scale variability, to be key to having cluster statistics approach power laws. The presence of such large-scale dynamics is reflected in steep vertical velocity spectra. Large-scale rising and sinking modulate the column water vapor and temperature field, leading to a heterogeneous distribution of moist and dry patches and regions of strong mass flux, in which large precipitation clusters form. Our findings suggest that power laws in Earth's precipitation cluster statistics stem from the robust power laws of atmospheric motions.

Adherence to outpatient care among individuals with pre-existing psychiatric disorders following the 2024 Noto Peninsula Earthquake: A retrospective study.

The study aim was to investigate the effect of the 2024 Noto Peninsula earthquake on regular psychiatric outpatient check-ups at Kanazawa Medical University Hospital, Japan. We retrospectively collected electronic medical records from January 4 to January 17, 2024, and analyzed data from 656 patients. χ 2 was used to analyze the association between adherence to scheduled visits and related factors, and the association between inability to attend scheduled visits and self-reported earthquake-related reasons among 84 nonadherent patients. A geographical information system was used to analyze geographic characteristics, such as municipality of residence and seismic intensity distribution. Of the 656 patients, 572 (87.2%) adhered to their scheduled visits. The failure to keep appointments was significantly associated with residence in areas with a seismic intensity of ≥6 (n = 21, 35.6%; p < 0.001). Among the 84 patients who failed to keep appointments, the inability to keep appointments owing to earthquake-related reasons was significantly associated with residence in areas with a seismic intensity of ≥6 (n = 16, 76.2%; p < 0.001) and presence of an F3 main disease code: Mood (affective) according to the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (n = 12, 60.0%; p = 0.034). Patients in areas with higher seismic intensity were more likely to miss appointments, probably because of factors such as infrastructure damage and personal losses. Among patients who missed appointments, those with F3 diagnoses were more likely to cite earthquake-related reasons. However, the high overall appointment adherence rate despite the effects of a major earthquake warrants further study.

Two-photon nanolithography of sub-micrometer thickness microlenses designed by NPCC assisted Rayleigh Sommerfeld diffraction integral

Recent development of artificial neural networks (ANNs) and inverse design methods have demonstrated their prospective significance for planar diffractive lens design, with a plethora of optical lenses designed for wavelengths ranging from visible to Thz wavelengths. However, previous research to design planner diffractive lenses only considers the maximum intensity in the focus area or its derivatives as the optimization function, leaving the intensity outside the focus area unconsidered. We proposed and investigated a two-dimensional (2D) physics-driven ANN method assisted by the negative Pearson correlation coefficient (NPCC) to design microlenses with varied focusing distances, which takes the entire 2D intensity distribution at the focus plane as an optimization function. Taking advantage of 3D two-photon nanolithographic technology, sub-micrometer thickness microlenses with varied focusing lengths are designed and fabricated, achieving an average focusing efficiency of around 35%, and an average focusing spot size of about 1 µm. Furthermore, a microlens array (19 by 19 microlenses with a total size of 4 mm2) with a curved focusing plane was fabricated and integrated into a CMOS sensor, achieving direct object imaging under incoherent white light illumination. Our results demonstrate that the NPCC is a very useful optimization function for designing planar diffractive lenses, and the use of NPCC in ANNs is of great potential for the future design of functional diffractive optical elements in optics and nanophotonics.

Phase control method for generating orbital angular momentum beams using coherent beam combining based on deep learning

In recent years, orbital angular momentum (OAM) beams have shown great potential for applications in laser communication, laser processing, optical imaging, and detection. For free-space optical communication, high-power, high-quality vortex beams with a high signal-to-noise ratio are critical for long-distance communication. Coherent beam combining (CBC) of vortex beams enables the enhancement of power while maintaining high beam quality. Considering the orbital angular momentum spectrum as a new dimension of optical wave resources, achieving rapid phase locking of specific phases is crucial for increasing communication capacity. Traditional phase control methods based on wavefront intensity distribution face limitations in optimization, particularly for centrosymmetric laser phased arrays. To address this, we propose a deep learning-based method using spiral phase modulation. By designing a loss function that eliminates phase periodicity, we establish a nonlinear mapping between the sub-beam phases and the far-field image. To improve the phase prediction accuracy of the deep learning model, we introduce a power-in-the-bucket (PIB) metric for the vortex beam’s main lobe, which mitigates dynamic phase errors caused by thermal and environmental disturbances. This method holds promise for application in high-power vortex beam optical systems with coherent combining of fiber laser phased arrays.

Shaping picosecond quasi-triangular laser pulses during the sum frequency generation

Numerical methods were used to show that chirped ultraviolet (UV) laser pulses of picosecond duration with quasi-triangular temporal intensity distribution may be shaped during collinear sum frequency generation by super-Gaussian pulses with opposite frequency chirps.

Vectorial acousto-optic Raman–Nath diffraction effect of chiral liquid media

The acousto-optic Raman–Nath (RN) diffraction effects of vector beams diffracted by the chiral ultrasonic grating are demonstrated experimentally and theoretically. The deviation of left- and right-handed circularly polarized components in higher-order diffraction light leads to the rearrangement of their polarization states and intensity due to the different refractive indices of left- and right-hand circularly polarized lights. When the difference between the refractive indices for left- and right-hand circular polarizations is small, linear polarization components of the higher-order diffraction light with the input localized linearly polarized vector optical field rotate compared to the zero-order diffraction light. Novel, to the best of our knowledge, intensity distributions of linear polarization components appear for the input hybridly polarized vector beam.

Investigation on Thermal Environment of Urban Slow Lane Based on Mobile Measurement Method—A Case Study of Swan Lake Area in Hefei, China

Abstract: Numerous issues with the urban thermal environment have been brought on by the rapid development of urbanization. The thermal climate of the slow lane, a major urban activity area, is directly tied to the well-being and comfort of city dwellers. The Swan Lake area in Hefei was chosen as the research site for this paper. The mobile measurement method was used to determine the heat island intensity distribution of the slow lane in each season of the year. The effects of building density, the percentage of permeable underlying surface, and shading on the slow lane’s thermal environment were then thoroughly examined. According to the study, the distribution of heat island intensities along the mobile measurement route varies significantly depending on season, as well as time of year. Summer and winter have the most notable variations in the distribution of heat island intensities along the mobile measurement route; the summer values range from 0.1 to 4, while the winter values range from −0.3 to 3. The results showed a maximum difference of 30.2 °C in surface temperature (Ts) readings and 11.9 °C in air temperature (Ta) readings between the identical sites with and without shading, according to tests conducted at four typical mobile measurement locations along the mobile measuring route. The shading factor has a greater effect on the slow lane’s thermal environment than permeable underlying surface and building density, as seen by the standardized coefficient of shading being significantly higher than both of these factors. With a standardized coefficient of shading of −0.493 in the winter and a standardized coefficient of shading of −0.517 in the summer, the effect of the shading factor on the thermal environment is more noticeable in the summer.

Cumulant method for identifying spatial distributions of laser beam intensity

Cumulant method for identifying spatial distributions of laser beam intensity

CAYSS: Package for Automatic Cytometry Analysis of Yeast Spore Segregation.

Meiotic recombination is a powerful source of haplotypic diversity, and thus plays an important role in the dynamics of short-term adaptation. However, high-throughput quantitative measurement of recombination parameters is challenging because of the large size of offspring to be genotyped. One of the most efficient approaches for large-scale recombination measurement is to study the segregation of fluorescent markers in gametes. Applying this to yeast spores by flow cytometry has already been proved to be highly efficient, but manual analyses of distributions of signal intensities is time-consuming and produces nonperfectly reproducible results. Such analyses are required to identify events corresponding to spores and to assign each of them to a genotypic class depending on their fluorescence intensity. The CAYSS package automatically reproduces the manual process that we've been developing to analyze yeast recombination for years, including Maximum-Likelihood estimation of fluorescence extinction (Raffoux et al. 2018a). When comparing the results of manual versus CAYSS automatic analyses of the same cytometry data, recombination rates and interference were on average very similar, with less than 3% differences on average and strong correlations (R2 > 0.9). In conclusion, as compared to manual analysis, CAYSS allows to save a lot of human time and produces totally reproducible results.