Phase Step Research Articles

Fresnel biprism common-path low-coherence digital holography for dynamic light scattering spectroscopy of biological materials

Doppler frequency shifts associated with the motions in cells range from mHz to Hz, requiring ultra-stable interferometry to capture frequency offsets at several parts in 1018. Common-path interferometers minimize the influence of mechanical disturbances when the signal and reference share common optical elements. In this paper, multi-mode speckle self-referencing via a Fresnel biprism demonstrates frequency stability down to 1 mHz. A low-coherence NIR source creates an OCT-like pseudo-coherence-gate in Fourier-domain holography without phase stepping, and the Fourier reconstruction of the self-referencing speckle fields produces an image-domain autocorrelation of the target. Fluctuation spectroscopy of dynamic speckle is performed on a semi-solid lipid emulsion that captures Brownian thermal signatures and on feline tissue culture that measures active intracellular transport. The extension of biodynamic imaging to lower frequencies opens the opportunity for studies of cell crawling in macroscopic living tissues.

Supplementation with essential amino acids in the early stage of carbohydrate reintroduction after a very-low energy ketogenic therapy (VLEKT) improves body cell mass, muscle strength and inflammation

BackgroundAlthough little is yet known about the long-term maintenance of very low-energy ketogenic therapy (VLEKT) effects on body composition, muscle strength and inflammation, it is plausible to assume that changes may occur, particularly during the steps following the ketogenic step, due to the loss of the protective effects of ketones and the concomitant reintroduction of carbohydrates. For this reason, the present study aimed to evaluate the effects of supplementation with 8 g per day of essential amino acids (EAAs) on these parameters.MethodsA total of 68 women of reproductive age and with grade I obesity who had completed 45 days of the ketogenic phase with VLEKT (KeNuT protocol) and 40 days of non-ketogenic phase of KeNuT protocol with VLEKT (phase 3, fruit reintroduction) were included in the study. Half of them (n = 34) followed this first step of the re-educational phase of KeNuT protocol with VLEKT with supplementation with EAAs (Aminotrofic®: 4 g twice daily). Anthropometric parameters, body composition via bioelectrical impedance analysis and high-sensitivity C-reactive protein (hs-CRP) levels were assessed at baseline, pre- and post both dietary interventions.ResultsAt the end of 45 days of ketogenic phase with VLEKT (before fruit reintroduction and EAA supplementation), the two groups did not differ in any of the parameters assessed. At the end of the fruit reintroduction phase, the supplemented group showed greater magnitudes of reduction in weight, waist circumference, fat mass (FM) and hs-CRP (p < 0.001 for all) and of increase in muscle strength (p < 0.001), phase angle (p < 0.001), body cell mass (BCM) (p = 0.001), and muscle mass (%) (p < 0.001).ConclusionThese results underline the usefulness of supplementation with EAAs during the first transitional phase post VLEKT to improve body composition (specifically reduction in FM and increase in BCM), muscle strength, and inflammatory status.

Macrolactin a is an inhibitor of protein biosynthesis in bacteria.

Macrolactin A (McA) is a secondary metabolite produced by Bacillus species. It has been known for its antimicrobial properties since the late 1980s, although the exact mechanism of its antibacterial activity remains unknown. In this study, we have found that McA is an inhibitor of protein synthesis in bacteria. Our conclusion is based on the results obtained by invivo and invitro bioreporter systems. We demonstrated that the inhibitory activity of McA is independent of bacterial species. However, the concentration of McA required to inhibit protein synthesis in the E.coli cell-free translational model was found to be 50 times lower than the concentration required in the S.aureus cell-free translational model. To investigate the mechanism of McA's inhibitory activity, we conducted a toe-printing assay, sequenced and annotated the genomes of McA-resistant Bacillus pumilus McAR and its parental strain. The results showed that McA inhibits the initial step of the elongation phase of protein synthesis. We identified single and multiple nucleotide polymorphisms in the gene encoding the translation elongation factor Tu (EF-Tu). Molecular modeling showed that the McA molecule can form non-covalent bonds with amino acids at the interface of domains 1 and 2 of EF-Tu. A cross-resistance assay was conducted using kirromycin on B.pumilus McAR. The results confirmed the assumption that McA has a mode of action similar to that of other elfamycin-like antibiotics (targeting EF-Tu). Overall, our study addresses a significant gap in our understanding of the mechanism of action of McA, a representative member of the macrolide antibiotics.

Accelerometers can correctly count orthopaedic patients' early post-operative steps while using walking aids.

Effective rehabilitation after orthopaedic surgery is critical. The early post-operative phase is increasingly managed in outpatient settings, necessitating objective measures such as step counts to monitor rehabilitation progress. However, it remains unclear if commercially available wearables or accelerometers using simple algorithms can accurately count steps in early post-operative conditions. We hypothesised that only accelerometers could accurately determine the number of steps under these conditions. This case series involved 20 healthy subjects, 7 female and 13 males, walking in a circle at varying speeds under partial loading with three different walking aids (forearm crutches, walking frame and rolling walker) and four wearables (Vivofit 4, Fenix 3HR, Fitbit Charge 3 and Omron HJ-325) and one accelerometer (AX6) worn on the wrist, hip and ankle. The two-point and modified three-point gait patterns commonly used post-operatively were simulated. The primary end point was the relative error (RE), defined as RE = (manual count - automated count)/manual count, of each wearable measurement compared to visual and video step counting, the gold standard. The RE of AX6 and Fitbit was less than 0.1 for all walking aids except the rolling walker, with AX6 showing the lowest standard deviation (SD) compared to other wearables. Other wearables had significantly higher RE. Increased gait speed generally improved accuracy, reducing RE in most devices, except for the AX6, which showed the opposite trend. At 0.6 m/s, only AX6 achieved an RE below 0.1. The ankle was identified as the best measuring location. During the early post-operative period, commercial wearables can only accurately count steps under specific conditions and should be used cautiously for monitoring steps in the early post-operative phase. However, accelerometers with appropriate coding appear suitable for this purpose. Level III diagnostic study.

Investigations of signal estimation bias in X-ray dark-field imaging using dual phase grating interferometer

Abstract In X-ray dark-field imaging using dual phase grating interferometer, multi-contrast signals are extracted from a set of acquired phase-stepping data by using least-squares fitting algorithm. The extracted mean intensity, amplitude and visibility signals may be intrinsically biased. However, it is still unclear how large these biases are and how the data acquisition parameters influence the biases in the extracted signals. And this work set out to address these questions. Analytical expressions of the biases of the extracted signals were theoretically derived by using a second-order Taylor series expansion. Extensive numerical simulations were performed to validate theoretical results. It is illustrated that while the estimated mean intensity signal is always unbiased, the estimated amplitude and visibility signals are both positively biased. While the biases of estimated amplitude signals are proportional to the inverse of the total number of phase steps, the biases of estimated visibility signals are inversely proportional to the product of the total number of phase steps and the mean number of photons counted per phase step. Meanwhile, it is demonstrated that the dependence of the biases on the mean visibility is quite different from that of Talbot-Lau interferometer, due to the difference in the intensity model. We expect that those results can be useful for data acquisition optimizations and interpretation of X-ray dark-field images.

Phase calibration of spatial light modulators using self-generated phase-discontinuity.

In this paper, we introduce a new method for precise determination of the calibration function of liquid crystal spatial light modulators (LC-SLMs). The proposed method shares the advantages of commonly used methods, interferometric and diffraction-based methods, and is free of their disadvantages. The method proposed here is based on the evaluation of Fresnel diffraction of light from a phase-discontinuity pattern loaded into the SLM device. In one version, the phase step pattern consists of two parts, one remains constant at zero, while the other changes with steps of 5 from 0 to 255 gray levels, for each measurement. By fitting the experimental intensity distribution measured in this configuration on the corresponding theoretical intensity distribution, complete phase calibration can be obtained. We also propose a second version, employing a phase wedge pattern, allowing the phase calibration curve of the SLM to be determined by just a single frame measurement which is a great asset.

A 2-oxoglutarate-dependent dioxygenase, GLUCORAPHASATIN SYNTHASE 1(GRS1) is a major determinant for different aliphatic glucosinolates between radish and Chinese cabbage.

Glucosinolates (GSLs) are secondary metabolites in Brassicaceae plants and play a defensive role against a variety of abiotic and biotic stresses. Also, it exhibits anti-cancer activity against cancer cell in human. Different profiles of aliphatic GSL compounds between radish and Chinese cabbage were previously reported. However, molecular details underlying the divergent profile between two species were not clearly understood. In this study, we found that major difference of aliphatic GSLs profiles between two species is determined by the dominantly expressed genes in first step of the secondary modification phase, which are responsible for enzymatic catalysis of methylthioalkyl-glucosinolate. For instance, active expression of GLUCORAPHASATIN SYNTHASE 1 (GRS1) gene in radish play an important role in the production of glucoraphasatin (GRH) and glucoraphenin (GRE), a major aliphatic GSLs in radish. Meanwhile, Chinese cabbage was found to merely produce glucoraphasatin (GRH), instead producing glucoraphanin (GRA) and gluconapin (GNP) due to the mere expression of GRS1 homologs and abundant expressions of FLAVIN-CONTAINING MONOOXYGENASES (FMO GS-OX) homologs in Chinese cabbage. In addition, we noticed that wounding treatment on leaf tissues substantially enhanced the production of aliphatic and benzenic GSLs in both Chinese cabbage and radish, indicating that GSLs are wound-induced defensive compounds in both Chinese cabbage and radish plants.

Impact of Hydraulic Resistance on Spatiotemporal Characteristics of Initial Six Steps When Sprinting Under Varying Loads.

Background: Evaluations of the usability of hydraulic resistance for resisted sprint-training purposes remains rare. Thus, this study compared step-by-step changes in spatiotemporal characteristics during the first 10 m of sprints with varying hydraulic resistance loads. Methods: Fourteen male athletes performed 20 m sprints under minimal (10 N, considered as normal sprint), moderate (100 N), and heavy (150 N) hydraulic resistance loads. Split times at 10 m, contact time (CT), step length (SL), flight time, and step speed (SS) from the first to the sixth step were measured. A two-way repeated measures ANOVA (load × step) and a one-way ANOVA (load) with post hoc comparisons were used to assess the effects on spatiotemporal characteristics and split times, respectively. Results: Under higher loads, the 10 m times were significantly longer (η2 = 0.79). The CT, SL, and SS varied significantly from step to step within all loads (η2 = 0.45, 0.41, and 0.54, respectively). The CT, SL, and SS of the first, fourth, fifth, and sixth steps of normal sprint differed significantly from most steps under moderate and heavy load (Cohen's d = -3.09 to 5.39). In contrast, the smallest differences were observed between the second and third step of normal sprint and second to sixth steps under heavy load (Cohen's d = -0.67 to 1.32, and -0.71 to 1.38, respectively). Conclusions: At the same load settings, a hydraulic resistance device induces changes in step characteristics comparable with those of other motorized devices and is therefore a viable option for resisted sprint training. If the goal of the training is to replicate the steps of the initial sprint acceleration phase, ~150 N of hydraulic resistance would be optimal.

Acute effects of different loading protocols upon performance and kinematics of 180 degrees change of direction

ABSTRACT This study examined the acute effects of different loading protocols on 180° change of direction (COD) performance in eleven male handball players. Participants performed a 10-0-5 COD test under seven conditions: without an external load, and with 3, 6, and 9 kg loads applied under two modes—assisted into the COD and resisted out of it and resisted into the COD and assisted out of it. While total COD time was not affected (p = 0.098; η2 = 0.16), significant phase effects were observed (p < 0.001; η2 ≥ 0.55). Loading protocols significantly influenced velocity, acceleration, and their distances from COD (p < 0.001; η2 ≥ 0.37). Significant phase effects were observed for all step kinematic variables (p ≤ 0.037; η2 ≥ 0.67), except contact time, and significant interaction (phase*condition) effects for all variables (p ≤ 0.004; η2 ≥ 0.08), except for step frequency. Assisted-resisted protocols increased deceleration demands through higher COD entry velocities, displaying fewer but longer steps in the acceleration phase and greater steps taken during the deceleration phase. Resisted-assisted protocols decreased deceleration demands due to lower COD entry velocities, displaying shorter, but more steps taken in the acceleration phase, and fewer steps taken in the deceleration phase. These findings suggest that assisted-resisted and resisted-assisted loading protocols can be used to selectively overload specific phases of COD performance.

Development and Application of Reservoir Operation Method Based on Pre-Release Index for Control of Exceedance Floods

The pre-release operation has the potential to enhance the ability of a reservoir to manage exceedance floods. However, the mechanisms for the initiation and termination of such operations are unclear, and a clear method for calculating the pre-release water amount at each time step of the scheduling phase is lacking. To address this, the framework and mathematical expression for a pre-release index are proposed herein, and a refined pre-release scheduling model is developed based on the pre-release indices and their thresholds. Then, the proposed pre-release operation model is applied to the Shuifumiao Reservoir in the Lianshui River Basin in Hunan Province, China. The simulation results demonstrate that the refined pre-release scheduling model can effectively prevent exceedance floods, ensuring the safety of flood control without compromising the effectiveness of water supply safety. The proposed model provides a valuable framework and tool for enhancing the ability of reservoir operators to manage flood events and improve overall flood control safety.

Less is more: adjusting convergence of Cooper’s algorithm in the continuous location-allocation problem

This paper proposes a variant of the well-known heuristic by Cooper for continuous location-allocation problems in general, and in particular, the continuous p-median problem. This algorithm alternates between a location phase where the allocations are fixed and an allocation phase where the locations of the p new facilities are fixed. The main idea of the proposed variant is to partially solve the p independent one-median problems in the location phase (instead of solving optimally) in order to induce a larger number of cycles of location-allocation. In effect, we are trying to alter the descent path of the algorithm by slowing the convergence rate using smaller descent steps in the location phase. Computational experiments show that this approach is highly effective in finding alternate descent paths that lead to “deeper” local minima. The best improvements are obtained with random starting locations of the p facilities, and the larger values of p that were tested.

Efficient Phase Step Determination Approach for Four-Quadrant Wind Imaging Interferometer

A four-quadrant wind imaging interferometer is a new generation of wind imaging interferometer with the valuable features of being monolithic, compact, light, and insensitive to temporal variations in the source. Its applications include remote sensing of the wind field of the upper atmosphere and observing important dynamical processes in the mesosphere and lower thermosphere. In this paper, we describe a new phase step determination approach based on the Lissajous figure, which provides an efficient, accurate, and visual method for the characterization and calibration of this type of instrument. Using the data from wavelength or thermal fringe scanning, the phase steps, relative intensities, and instrument visibilities of four quadrants can be retrieved simultaneously. A general model for the four-quadrant wind imaging interferometer is described and the noise sensitivity of this method is analyzed. This approach was successfully implemented with four-quadrant wind imaging interferometer prototypes, and its feasibility was experimentally verified.

Scattering-Free and Fast Response Polymer Brush-Stabilized Liquid Crystals Beam Steering Using Surface-Initiated Polymerization Technique.

Nonmechanical fast response optical beam steering technology is increasingly essential for telecommunications, imaging systems, optical sensing, displays, and military applications. Polymer network liquid crystal (PNLC) beam steering can achieve submillisecond response times but faces limitations due to scattering issues arising from the refractive index mismatch between the polymer network and the liquid crystals (LCs). In this article, we demonstrate a scattering-free, fast-response LC beam steering by using polymer brushes to stabilize the gradient refractive index. First, the initiator is incorporated into the alignment layer and the monomer is mixed into the LC layer. Surface-initiated polymerization (SIP) is then employed to grow the polymer brushes exclusively on the substrate's surface, thus confining the polymer network's growth to the LC bulk and reducing interfacial scattering. For polymer brush stabilized liquid crystal (PBSLC) beam steering device with a period size of 225 μm and a cell gap of 7.2 μm, the average transmission rate reaches 88% in the visible light spectrum with a haze value of only 6.91. The steering angle is 0.16, and the diffraction efficiency is 80.3%. When a voltage of 35 Vrms is applied, the primary energy can be tuned to the zeroth order, with a response time close to 1 ms. By cascading two PBSLC beam steering devices with opposite steering directions, the primary energy of the beam can be adjusted between zeroth, +1, and -1 order. This method requires only a UV light source, a precision displacement stage, a power supply, and a mask, avoiding the need for expensive equipment and complex electrode fabrication. By adjustment of the phase change period, step width, and number of steps during fabrication, the steering angles and diffraction efficiency of the PBSLC beam steering device can be easily controlled, highlighting its significant potential for industrial production.

Multi-plane light conversion (MPLC) LP mode multiplexer based on grayscale maskless lithography.

Multi-plane light conversion (MPLC) is a technique that uses multiple phase plates to modulate a light beam step-by-step. This technique has attracted widespread attention in the field of mode-division multiplexing (MDM) communications due to its high flexibility. MPLC device requires precisely controlled fabrication accuracy in experiments, but conventional multi-etching processes will accumulate alignment errors. Here, the fabrication of the MPLC device using maskless grayscale lithography was proposed, which requires only a single-exposure process. Through single-exposure lithography, the continuous phase of the digital mask ranging from 0 to 2π on MPLC is discretized into 128 steps. The digital masks of the MPLC with more steps of phase can reduce the insertion loss and mode crosstalk of LP modes. By using the fabricated MPLC, we experimentally demonstrate the MDM of LP01, LP11a, LP11b, and LP21 modes with mode crosstalk less than -22 dB, and the insertion loss less than 4 dB. In high-speed optical communications, each LP mode carries a 10 Gbit/s on-off keying (OOK) signals, and the experimentally measured bit error rates (BER) curves power penalty is less than -7 dB. The experiment demonstrated that maskless grayscale lithography can efficiently and accurately fabricate MPLC mode multiplexers.

Optimization of Data Management through a Web System based on Business Intelligence and Agile Kanban Methodology

The collection of information through a questionnaire for planning purposes played an important role in defining the requirements of the web system, functioning as a fundamental basis for the next step in the software development phase. The application of the Kanban way of thinking has proven to be effective in managing work, supported by greater openness during the system creation phase. The surveys and interviews carried out show that the initiative is important and necessary to improve decision-making and processes. The incorporation of Kanban principles is based on an exhaustive analysis using tools such as PHP, Bootstrap and MySQL to facilitate the process and achieve maximum efficiency. Through the web-based system, it is possible to centralize information, allowing its access and management in real time. Business intelligence is also used to perform in-depth analysis, helping to identify patterns and potential opportunities for improvement. It was considered appropriate to choose the Kanban methodology due to its collaborative and incremental approach, ideal for adapting to change and providing constant value. The results confirm the solidity of our methodology and the relevance of the choices made in the development of this web application based on Business Intelligence and Agile Kanban Methodology.

Development and validation of the self-report symptom inventory of immune-related adverse events in patients with lung cancer

This study aims to develop and validate the Self-Report Symptom Inventory of immune-related Adverse Events in Patients with Lung Cancer (SRSI-irAEs-LC) to allow for systematic assessment of symptomatic irAEs in patients with lung cancer treated with programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) immune checkpoint inhibitors (ICIs). A sequential two-phase mixed-methods study was conducted. In phase I, a draft version of the SRSI-irAEs-LC was constructed through item generation and draft inventory construction. Delphi expert consultation, cognitive interviews and a pilot study were conducted to evaluate the content validity and refine the scale. In phase II, psychometric testing was performed on 512 patients with lung cancer treated with PD-1/PD-L1 ICIs using item analysis, exploratory factor analysis (EFA), confirmatory factor analysis (CFA), criterion validity, discriminant validity, and reliability evaluations. Through 5 sequential steps in phase I, the preliminary version of the SRSI-irAEs-LC comprised 10 dimensions with 41 items. Through EFA, the final version of the SRSI-irAEs-LC included 8 dimensions and 26 items that explained 62.33% of the variance. The CFA model showed that the 8-factor model fitted the data well. Good criteria validity and known-groups discriminant validity were demonstrated. Cronbach's alpha, split-half reliability, and test-retest reliability of the scale were 0.824, 0.725, and 0.851, respectively. Preliminarily, the SRSI-irAEs-LC is a valid and reliable instrument for assessing symptomatic irAEs in patients with lung cancer treated with PD-1/PD-L1 ICIs. Further research is needed to confirm its generalizability to a broader population as well as its validity and reliability.

Static X-ray differential phase contrast imaging via bidirectional-misalignment grating

Static X-ray differential phase contrast imaging via bidirectional-misalignment grating

Hardware Testing Methodologies for Wide Bandgap High-Power Converters

Wide bandgap (WBG) power semiconductor devices are increasingly replacing silicon IGBTs in high-power and high-voltage power electronics applications. However, there is a significant gap in the literature regarding efficient testing methodologies for high-power and high-voltage converters under constrained laboratory resources. This paper addresses this gap by presenting comprehensive, hardware-focused testing methodologies for high-power and high-voltage WBG power semiconductor-based converter bring-up before the control validation phase steps in. The proposed methods enable thorough evaluation and validation of converter hardware, including device switching characteristics, driving circuit functionality, thermal management performance, insulation integrity, and sustained operation at full power. We utilized the double pulse test (DPT) to characterize switching performance in a two-level phase leg configuration, extract circuit parasitics, and validate magnetic components. The DPT was further applied to optimize gate driving circuits, validate overcurrent protection mechanisms, and measure device on-resistance. Additionally, a multicycle test was introduced to rapidly assess steady-state converter performance and estimate efficiency. Recognizing the critical role of thermal management in high-power converters, our methodologies extend to the experimental extraction of key thermal parameters—such as junction-to-ambient thermal resistance and thermal capacitance—via a heat loss injection method. A correlation method between temperature sensor measurements and junction temperature is presented to enhance the accuracy of device temperature monitoring during tests. To ensure reliability and safety, dielectric withstand tests and partial discharge measurements were conducted at both component and converter levels under conventional 60 Hz sinusoidal and high-frequency PWM waveforms. Finally, we highlight the importance of testing converters under full voltage, current, and thermal conditions through power circulating tests with minimal power consumption, applicable to both non-isolated and isolated high-power converters. Practical examples are provided to demonstrate the effectiveness and applicability of these hardware testing methodologies.

ANALYTICAL METHOD DEVELOPMENT AND VALIDATION FOR SIMULTANEOUS ESTIMATION OF CABOZANTINIB &amp; NIVOLUMAB IN COMBINED PHARMACEUTICAL DOSAGE FORMS BY RP-HPLC

A simple, accurate and precise HPLC method for simultaneous determination of Cabozantinib and Nivolumab in pure and tablet dosage form has been developed. HPLC of Waters (Model: Alliance 2695) with Phenomenax Luna C18(4.6 mm × 250 mm, 5 µm) column was used for chromatographic separation. Mobile phase consists of Methanol: Water (65:35% v/v) and flow rate adjusted was 1 ml/min. Wavelength selected for detection was 220 nm and injection volume was 10 µl. The method has been validated for linearity, accuracy, and precision. The linearity of Cabozantinib and Nivolumab were in the range of 30 μg/ml respectively. The developed HPLC method offers several advantages such as rapidity, usage of simple mobile phase and easy sample preparation steps. Further, improved sensitivity makes it specific and reliable for its intended use. Hence, this method can be applied for the analysis of pure drug and pharmaceutical dosage forms. From the present study it can be concluded that the proposed method is simple, sensitive, precise, specific, accurate and reproducible. Results of validation parameters demonstrated that the analytical procedure is suitable for its intended purpose and meets the criteria defined in ICH.

MFR-Net: A multi-feature fusion phase unwrapping method for different speckle noises

MFR-Net: A multi-feature fusion phase unwrapping method for different speckle noises