Basic principles of the TEVY index for the quantification of temperature variability within a year

In the context of climate change, there is a need for the determination of appropriate indexes for the quantification of temperature variability. A new index (TEVY index) is proposed in this work. This index uses the deviation of the observed temperature values from those estimated from a Fourier harmonic analysis. For this purpose, a nearly 50-year time series data from 4 stations in Greece, with very different climatic conditions, are used. One station is located in the colder northern region of Greece, another one is in the warmest southern part, while the 2 other stations are representative of continental and Mediterranean climatic features. A Fourier harmonic analysis is carried out to obtain the Fourier series which simulates the observed data time series. Fourier harmonic analysis, which is relied on the Fourier transform, is a well-established method for time series analysis, particularly for modelling periodic data. Using this procedure, an index of temperature variability is proposed, as the sum of the divergence of the above-mentioned Fourier series from the observed data. The index results are analysed as a function of the different climatic features of each station.

PSXII-17 Fertility prediction model for Nilli-Ravi buffalo bulls through Fourier harmonic analysis of sperm

A model to predict Nili-ravi buffalo bull fertility was developed based on Fourier harmonic analysis of sperm. Seventeen bulls with 3032 AI records were categorizes based on fertility rate (FR) as low (36.5±0.2, n = 6: SD< ˗1 from mean FR), medium (39.9±0.2, n = 3; SD +1 to -1 from mean FR) and high fertility (41.4±0.1, n = 8; SD > +1 from mean FR). Cryopreserved semen samples from these bulls were investigated for Fourier harmonic analysis of sperm nuclear shape. Hoechst-33342 and YOYO-1 fluorescent stains were used to identify live and dead sperm. Digital images were analyzed to get sperm nuclear perimeter points at different phase angles to generate Fourier functions. Mean harmonic amplitude (HA) 0 was different (P < 0.05) for 1700 live vs. 1294 dead sperm from the 17 bulls, thus live sperm were used for remaining analyses. The mean, variance, skewness and kurtosis values of 100 live sperm nuclei/bull were compared for HA0-5 between high (n = 6) and low (n = 6) fertility groups, considering equal number of bulls in each category. The mean HA2 (0.739±0.01 vs 0.686±0.00) and 4 (0.105±0.001 vs 0.007±0.001) were higher in high vs low fertility group respectively (P < 0.05). Sperm nuclear perimeter among high fertility group sperm was more elongated. There was also an increased skewness of HA0 as fertility increased (P < 0.05). Discriminant analysis defined a fertility model by using mean HA4, skewness HA0 and variance HA2, that resulted in 91.7% bulls into their correct fertility group upon cross-validation (canonical correlation=0.928; P < 0.05). Higher values of mean HA4, skewness HA0 and variance HA2 increase the chance of bulls being placed in the high fertility group. In conclusion, sperm nuclear shape in Nili-ravi buffalo bull is related to in vivo fertility. A fertility model using reported discriminant measures could be used to objectively identify Nili-ravi buffalo bulls of varying fertility.

Fourier-component engineering to control light diffraction beyond subwavelength limit

Resonant physical phenomena in planar photonic lattices, such as bound states in the continuum (BICs) and Fano resonances with 100% diffraction efficiency, have garnered significant scientific interest in recent years owing to their great ability to manipulate electromagnetic waves. In conventional diffraction theory, a subwavelength period is considered a prerequisite to achieving the highly efficient resonant physical phenomena. Indeed, most of the previous studies, that treat anomalous resonance effects, utilize quasiguided Bloch modes at the second stop bands open in the subwavelength region. Higher (beyond the second) stop bands open beyond the subwavelength limit have attracted little attention thus far. In principle, resonant diffraction phenomena are governed by the superposition of scattering processes, owing to higher Fourier harmonic components of periodic modulations in lattice parameters. But only some of Fourier components are dominant at band edges with Bragg conditions. Here, we present new principles of light diffraction, that enable identification of the dominant Fourier components causing multiple diffraction orders at the higher stopbands, and show that unwanted diffraction orders can be suppressed by engineering the dominant Fourier components. Based on the new diffraction principles, novel Fourier-component-engineered (FCE) metasurfaces are introduced and analyzed. It is demonstrated that these FCE metasurfaces with appropriately engineered spatial dielectric functions can exhibit BICs and highly efficient Fano resonances even beyond the subwavelength limit.

Comparison of corneal irregular astigmatism by the type of corneal regular astigmatism

We investigated the relation between corneal regular and irregular astigmatism in normal human eyes. In 951 eyes of 951 patients, corneal irregular astigmatism, such as asymmetry and higher-order irregularity components, was calculated using the Fourier harmonic analysis of corneal topography data within the central 3-mm zone of the anterior corneal surface. The eyes were classified by the type of corneal regular astigmatism into four groups; minimum (< 0.75 diopters), with-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism. The mean age was significantly different among the four groups (P < 0.001); patients with WTR astigmatism were the youngest, followed by those with minimum, oblique, and ATR astigmatism. Significant inter-group differences were found among the four groups in asymmetry (P = 0.005) and higher-order irregularity components (P < 0.001); the largest was in eyes with oblique astigmatism, followed by ATR, WTR, and minimum astigmatism. The stepwise multiple regression analysis revealed that corneal regular astigmatism pattern significantly influenced the amount of corneal irregular astigmatism after controlling for confounding factors (P < 0.001). Corneal irregular astigmatism, such as asymmetry and higher order irregularity components, was the largest in eyes with oblique astigmatism, followed by those with ATR, WTR, and minimum astigmatism, even after adjustment for age of subjects.

Annual Cycle of East Asian Precipitation Simulated by CMIP6 Models

Annual cycle is fundamental in the East Asian monsoon (EAM) systems, profoundly governing the spatiotemporal distribution of the East Asian rainfall. The present study identified the dominant modes of the annual cycle in the East Asian rainfall based on the Fourier harmonic analysis and the Empirical Orthogonal Function (EOF) decomposition. We evaluated the performance of the first two leading modes (i.e., EOF-1 and EOF-2) in historical experiments (1979–2014) of the 21 released climate models of phase six of the Coupled Model Intercomparison Project (CMIP6). Comparing with the observation, although the CMIP6 models yield the essential fidelity, they still show considerable systematic biases in the amplitude and phase of the annual cycle, especially in east and south China. Most models exhibit substantial phase delays in the EOF-2 mode of the annual cycle. Some specific models (BCC-ESM1, CanESM5, and GFDL-CM4) exhibiting better performance could capture the observed annual cycle and the underlying physics in climatology and interannual variability. The limited fidelity of the EOF-2 mode of the EAM annual cycle primarily hinders the monsoon variability simulation and thus the reliable future projection. Therefore, the dominant modes of the EAM annual cycle act as the evaluate benchmark in the EAM modelling framework. Their improvement could be one possible bias correction strategy for decreasing the uncertainty in the CMIP6 simulation of the EAM.

Corneal tomographic changes during corneal rigid gas-permeable contact lens wear in keratoconic eyes

Background/AimsWe aimed to investigate the refractive changes in the posterior corneal surface in keratoconus (KC) associated with wearing spherical corneal rigid gas-permeable contact lenses (corneal GPs) with apical touch or three-point touch fitting and the effect of spherical corneal GPs on corneal biomechanics.MethodsPatients with KC wearing corneal GPs every day without facing complications were enrolled as a single group. Corneal tomographic data were obtained using a three-dimensional anterior segment optical coherence tomography from the same eye with and without corneal GPs. Dioptric data from the central 3-mm zone of the posterior corneal surface were decomposed into spherical, regular astigmatism, asymmetry and higher-order irregularity components using Fourier harmonic analysis. The corneal biomechanical indices were deformation amplitude ratio within 2 mm, integrated radius, stiffness parameter at first applanation and linear Corvis Biomechanical Index. Correlations between the difference in Fourier indices with and without corneal GPs and the corneal biomechanical parameters were analysed.ResultsThirty-two eyes of 32 patients with KC were enrolled. Spherical, regular astigmatism and asymmetry components were significantly smaller with corneal GP wear than without the wear (all p<0.001). All biomechanical indices were significantly correlated with the difference in the spherical components with and without corneal GPs.ConclusionCorneal biomechanical properties of KC were correlated with posterior corneal surface flattening induced by wearing corneal GPs on the spherical components. This effect is greater in biomechanically weaker corneas.

PSII-33 Mitigation of testicular heat stress in boars with PG600

Testicular heat stress due to increasing summer temperatures negatively impacts spermatogenesis reducing semen quality in boars. Scrotal insulation (SI) can mimic summer heat stress. Our hypothesis is that PG600 can mitigate heat stress in boars. PG600 is human chorionic gonadotropin (HCG) and equine chorionic gonadotropin (ECG) which have LH- and FSH-like effects respectively. During spermatogenesis, LH impacts testosterone production by Leydig cells and FSH impacts Sertoli cells to produce androgen receptors, inhibit apoptotic signals and sustain spermatogenesis. Eight boars (8–12 months of age) were randomly assigned to two treatment groups: SI + saline or SI + PG600. The SI was applied for 48 hrs. Injections were administered 24 hrs prior to SI application and again at onset of SI. PG600 was given at a standard gilt dose to induce puberty. Semen was collected every M-W-F for two weeks prior to treatment and 44 days post-treatment. Semen was evaluated for nuclear head shape via Fourier harmonic analysis (FHA) described as Harmonic amplitudes 0–5 (HA0-5). Semen for each collection day post-treatment was compared to the average of the semen collection days pre-treatment, described as day 0. Scrotal insulation produced a 3.7°C increase in average scrotal temperature for 48 hrs. Post-SI + saline, HA0 decreased on days 21–33 (P &lt; 0.05), HA1 increased on day 30 (P &lt; 0.05), HA2 decreased on day 35 (P &lt; 0.05), HA3 increased on days 21–33 (P &lt; 0.05), HA4 increased on days 21–26 (P &lt; 0.05), and HA5 increased on days 21–30 (P &lt; 0.05). Post-SI + PG600, decreased the number of days post-SI when changes in harmonic amplitudes were seen (P &lt; 0.05) as well as the magnitude of the response (P &lt; 0.05). PG600 was for the first time shown to significantly mitigated the response of boars to SI and testicular heat stress. Increased doses of PG600 may improve results.

Corneal topography in keratoconus evaluated more than 30 years after penetrating keratoplasty: a Fourier harmonic analysis

The aim of this observational study was to examine the characteristics of anterior and posterior corneal topography in keratoconic eyes more than 30 years after penetrating keratoplasty (PK). Patients who maintained clear grafts for more than 30 years after PK were included and divided into the keratoconus (KC) group or other diseases (Others) group, based on the primary indication. Twenty-six eyes of 26 patients were included. The KC group and the Others group included 14 eyes and 12 eyes, respectively. The KC group participants were younger at the time of surgery (P = 0.03). No differences were found in best-spectacle-corrected visual acuity, keratometric power, and central-corneal-thickness. Based on corneal topography using Fourier harmonic analyses, regular astigmatism in the anterior cornea was significantly larger (P = 0.047) and the spherical component in the posterior cornea was significantly lower (P = 0.01) in the KC group. The area under the receiver operating characteristic curve of the spherical component, regular astigmatism, asymmetry component, and higher-order irregularity were 66.07%, 63.10%, 57.14%, and 59.23%, respectively, in the anterior cornea and 80.65%, 52.98%, 63.10%, and 63.99%, respectively, in the posterior cornea. Our results suggested that Fourier harmonic analysis of corneal topography could be useful for patients with KC long after PK.