Power Formula Research Articles

Research progress of new generation intraocular lens calculation formulas

With the development of the technology of phacoemulsification and intraocular lens (IOL) implantation, the calculation formula of IOL power has been optimized. The existing formulas are still not accurate enough for some special cases, such as patients with short or long axial length and previous corneal refractive surgery, because the calculation of IOL power is a nonlinear function, and these mathematical formulas based on an optical model can not show the nonlinear relationship well. Therefore, new IOL calculation formulas developed by using an artificial intelligence nonlinear mathematical model have come into being. This review demonstrates the development and application of new IOL calculation formulas, in order to provide guidance for improving the visual quality and clinical application of each calculation method in cataract patients.

Accuracy of Formulas for Intraocular Lens Power Calculation After Myopic Refractive Surgery.

To assess the accuracy of the following intraocular lens (IOL) power formulas: Barrett True-K No History (BTKNH), Emmetropia Verifying Optical 2.0 Post Myopic LASIK/PRK (EVO 2.0), Haigis-L, American Society of Cataract and Refractive Surgery (ASCRS) average, and Shammas, designed for patients who have undergone previous myopic refractive surgery, independent of preexisting clinical history and corneal tomographic measurements. Data from 302 eyes of 302 patients who previously underwent myopic refractive surgery and had cataract surgery done by a single surgeon with only one IOL type inserted were included. The predicted refraction was calculated for each of the formulas and compared with the actual refractive outcome to give the prediction error. Subgroup analysis based on the axial length and mean keratometry was performed. On the basis of mean absolute prediction error (MAE), the formulas were ranked as follows: Haigis-L (0.61 diopters [D]), ASCRS average (0.63 D), BTKNH (0.67 D), EVO 2.0 (0.68 D), and Shammas (0.69 D). The Haigis-L had a statistically significant lower MAE compared with all formulas (P < .05) except the ASCRS average. Hyperopic mean prediction errors were seen in all formulas for axial lengths of greater than 30 mm or mean keratometry values of 35.00 diopters or less. The Haigis-L and the ASCRS average formulas provided the most accurate results in the overall population evaluated in this study. Moreover, according to data observed, it is important to be careful handling very long eyes and very flat corneas because hyperopic refractions could be more common. [J Refract Surg. 2022;38(7):443-449.].

Group sequential methods for the Mann-Whitney parameter.

Late phase clinical trials are occasionally planned with one or more interim analyses to allow for early termination or adaptation of the study. While extensive theory has been developed for the analysis of ordered categorical data in terms of the Wilcoxon-Mann-Whitney test, there has been comparatively little discussion in the group sequential literature on how to provide repeated confidence intervals and simple power formulas to ease sample size determination. Dealing more broadly with the nonparametric Behrens-Fisher problem, we focus on the comparison of two parallel treatment arms and show that the Wilcoxon-Mann-Whitney test, the Brunner-Munzel test, as well as a test procedure based on the log win odds, a modification of the win ratio, asymptotically follow the canonical joint distribution. In addition to developing power formulas based on these results, simulations confirm the adequacy of the proposed methods for a range of scenarios. Lastly, we apply our methodology to the FREEDOMS clinical trial (ClinicalTrials.gov Identifier: NCT00289978) in patients with relapse-remitting multiple sclerosis.

A primary proton integral depth dose calculation model corrected with straight scattering track approximation

PurposeProton therapy requires a highly accurate dose calculation model. The Bortfeld analytical formula (BAF) is a classical depth-dose calculation model that exhibits a dose deviation compared to the Monte Carlo simulation. This study focuses on the lateral scattering effect on depth dose deviation between model calculations and Monte Carlo simulations and provides a modified model to correct. MethodsOnly the dose contributed by the primary particles was studied in this work. The Bethe stopping power formula was applied to reduce the deviation in the flat region. The proton track lateral scattering is considered to reduce the deviation in the Bragg peak region. Lateral scattering tracks were approximated as straight lines and assumed to have a Gaussian slope distribution. The tracks were projected to the central axis to correct the depth-dose curve. The calculated dose was compared with a Geant4 simulation. Four proton beams with energies of 50 MeV, 100 MeV, 150 MeV, and 200 MeV were calculated and verified. The dose deviation between the model calculation and Monte Carlo simulation was quantified under a dose and depth tolerance of 2%/1 mm with gamma analysis. ResultsThe straight scattering track approximation significantly reduced the primary dose deviation between the model calculation and the Geant4 simulation. The gamma values of all verified cases are below 1, which means that the deviation is acceptable under a given tolerance of 2%/1 mm. ConclusionsThis study proposes a modification of the primary depth-dose calculation model involving scattering-track correction. Good dose agreement between the calculation and Geant4 simulation was obtained. The modified model shows good accuracy in primary depth dose calculation and will be helpful for clinical application together with further secondary dose models, which are still under investigation.

Factorization for azimuthal asymmetries in SIDIS at next-to-leading power

Differential measurements of the semi-inclusive deep inelastic scattering (SIDIS) process with polarized beams provide important information on the three-dimensional structure of hadrons. Among the various observables are azimuthal asymmetries that start at subleading power, and which give access to novel transverse momentum dependent distributions (TMDs). Theoretical predictions for these distributions are currently based on the parton model rather than a rigorous factorization based analysis. Working under the assumption that leading power Glauber interactions do not spoil factorization at this order, we use the Soft Collinear Effective Theory to derive a complete factorization formula for power suppressed hard scattering effects in SIDIS. This yields generalized definitions of the TMDs that depend on two longitudinal momentum fractions (one of them only relevant beyond tree level), and a complete proof that only the same leading power soft function appears and can be absorbed into the TMD distributions at this order. We also show that perturbative corrections can be accounted for with only one new hard coefficient. Factorization formulae are given for all spin dependent structure functions which start at next-to-leading power. Prospects for improved subleading power predictions that include resummation are discussed.

Aladdin HW2.0 Optik Düşük Koherens İnterferometre ile Oküler Biyometri ve Pupillometrinin Yeniden Üretilebilirliği

Objective: The purpose of the study was to evaluate the reproducibility of ocular biometry and pupillometry with the Aladdin HW2.0 (Topcon, Tokyo, Japan) in patients with cataracts and healthy subjects.Materials and Methods: This prospective study was performed in eyes of healthy subjects and patients with cataracts. After a full ophthalmological examination; axial length (AL), anterior chamber depth (ACD), keratometry (K values), white-to-white (WTW), intraocular lens (IOL) powers, and pupillometric parameters were measured with the Aladdin biometer by two operators.Results: 72 eyes of 40 patients with cataracts and 57 eyes of 29 healthy subjects were evaluated. AL, ACD, K values, WTW and IOL power formulas were highly reproducible [intraclass correlation coefficient (ICC)&amp;gt;0.900] in two groups. AL was the most reproducible parameter in patients with cataracts, ACD in the healthy subjects. The ICC values of pupillometry were lower than 0.900 (range from 0.100 to 0.882) in patients with cataracts. The worst reproducible parameter was the maximum diameter of dynamic pupillometry. Except for the photopic pupil diameter from the healthy group, pupillometry parameters were within a quite wide range for 95% LoA.Conclusion: The Aladdin HW2.0 optical low coherence interferometer showed excellent inter-operator reproducibility for AL, ACD, K values, WTW and IOL power formulas except for pupillometry measurements.

Comparison of Intraocular Lens Power Formula Accuracy for Flanged Intrascleral Intraocular Lens Fixation

Comparison of Intraocular Lens Power Formula Accuracy for Flanged Intrascleral Intraocular Lens Fixation

Innovative Approach for Controlling Black Rot of Persimmon Fruits by Means of Nanobiotechnology from Nanochitosan and Rosmarinic Acid-Mediated Selenium Nanoparticles.

The protection of persimmon fruits (Diospyros kaki L.) from postharvest fungal infestation with Alternaria alternata (A. alternate; black rot) is a major agricultural and economic demand worldwide. Edible coatings (ECs) based on biopolymers and phytocompounds were proposed to maintain fruit quality, especially with nanomaterials’ applications. Chitosan nanoparticles (NCt), rosmarinic acid bio-mediated selenium nanoparticles (RA/SeNPs) and their composites were produced, characterized and evaluated as ECs for managing persimmon black rot. The constructed NCt, RA/SeNPs and NCt/RA/SeNPs composite had diminished particles’ size diameters. The ECs solution of 1% NCt and NCt/RA/SeNPs composite led to a significant reduction of A. alternata radial growth in vitro, with 77.4 and 97.2%, respectively. The most powerful ECs formula contained 10 mg/mL from NCt/RA/SeNPs composite, which significantly reduced fungal growth than imazalil fungicide. The coating of persimmon with nanoparticles-based ECs resulted in a significant reduction of black rot disease severity and incidence in artificially infected fruits; the treatment with 1% of NCt/RA/SeNPs could completely (100%) hinder disease incidence and severity in coated fruits, whereas imazalil reduced them by 88.6 and 73.4%, respectively. The firmness of fruits is greatly augmented after ECs treatments, particularly with formulated coatings with 1% NCt/RA/SeNPs composite, which maintain fruits firmness by 85.7%. The produced ECs in the current study, based on NCt/RA/SeNPs composite, are greatly recommended as innovatively constructed human-friendly matrix to suppress the postharvest destructive fungi (A. alternata) and maintain the shelf-life and quality of persimmon fruits.

Optimized power and water allocation in smart irrigation systems

Agriculture has a significant role in countries’ economy, but irrigation process consumes both power and water resources. Since in agriculture the goal is to maximize crop’s yields with minimize costs, it is important to design a national smart irrigation system with optimal allocation of power and water resources especially in a plantation area with little rains. In this work, an optimized on-demand smart irrigation system is proposed to manage the allocation of the consumed power and water in agriculture field. The system controls irrigation process by utilizing Wireless Sensor Network (WSN) to collect real-time data from the field using sensors. Raspberry pi takes appropriate decision about irrigation process according to received data from sensor nodes, and commands are sent from it to actuator nodes. Secured Message Queuing Telemetry Transport (MQTT) protocol with Transport Layer Security (TLS) authentication protocol is used in managing the data exchange in the network over Wi-Fi technology. In addition, an optimal power and water consumptions formula is derived using Lagrange Multiplier method to allocate resources in an optimal way depending on watering demands. Both theoretical and practical results approve the efficiency of the proposed system in managing irrigation process optimally.

Low voltage ride-through control strategy for a wind turbine with permanent magnet synchronous generator based on operating simultaneously of rotor energy storage and a discharging resistance

When the low voltage ride-through(LVRT) method of combining rotor energy storage with a discharging resistance for a wind turbine with permanent magnet synchronous generator(PMSG) is adopted, with the traditional control strategy, there are the shortcomings of the rotor energy storage function not exerted to the maximum extent and the large discharging current flowing through the discharging resistance. On the above shortcomings, a LVRT control strategy for a wind turbine with PMSG based on operating simultaneously of rotor energy storage and a discharging resistance is presented. On the basis of the rotor motion equation, the setting calculation formula of the active power of machine-side converter for maximizing the performance of the rotor energy storage is derived, and the switching method of the discharging resistance is designed. Simulation examples of a wind turbine with PMSG rating of 1.5MW are constructed using PSCAD/EMTDC to compare the proposed LVRT control strategy with the traditional control strategy according to the LVRT requirements of China National Standard for a wind turbine generator system. The simulation results show that the proposed LVRT strategy can not only exert the rotor energy storage function to the maximum extent, but also significantly reduce the discharging current, which verifies the effectiveness of the proposed LVRT control strategy.

CA-530-01 USE THE FORCE: ADEQUATE CATHETER CONTACT FORCE IS CRITICAL FOR HIGH QUALITY LESIONS GUIDED BY ABLATION INDEX

Ablation Index (AI) is a measure used to estimate lesion size based on power, contact force (CF), and lesion duration. Ideally, AI-guided titration of lesion duration corrects for variations in contact force. Impedance drop is a validated measure that correlates well with lesion formation. Therefore, analysis of the relationship between AI, CF, and impedance drop may offer insight into possible residual influences of CF on lesion formation. To investigate and characterize the impact of CF on impedance drop during AI-guided ablation. We retrospectively reviewed atrial fibrillation ablation cases (AFAs) performed at a single center. We examined the correlation between CF and Impedance drop within narrow ranges of AI (17 groups). In a secondary analysis, we matched lesion pairs with high and low CF (< 10 g and > 20 g) for stability, AI, lesion location, and power. Matched pairs were compared using a t-test. There were 13444 lesions with AI between 320 and 530 from 91 AFAs. For lesions that had a low AI (< 402.3), we observed mostly no residual correlation between contact force and impedance drop ( Fig 1). For lesions with high AI (> 402.3), we observed a consistent significant correlation between CF and impedance drop (Fig 1). In the matched sample, the high CF group had a greater impedance drop when compared to the low CF group: 8.5 ±5.3 vs 7.0 ±4.0 Ohms p < 0.01 (Figure 2), despite having similar AI. When examining the subset of matched pairs with AI < 400, we observed no significant difference in impedance drop between the high and low CF groups: 6.7 ±4.7 vs 6.5 ±4.1 Ohms (p = 0.6). When examining the matched pairs with AI > 400, we again observed a significant difference: 9.8 ±5.3 vs 7.3 ±3.9 Ohms p < 0.01 (Fig 2). Contact force had an important residual impact on impedance drop in high AI lesions ( > 400) but not in low AI lesions (< 400). This may be due to differences in conductive versus resistive heating requirements. Ablation Index using a fixed formula for duration, force, and power, may not accurately predict lesion formation throughout all value ranges and optimization of adequate contact force remains important for larger and deeper lesions.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Calculating power for the Finkelstein and Schoenfeld test statistic for a composite endpoint with two components.

The Finkelstein and Schoenfeld (FS) test is a popular generalized pairwise comparison approach to analyze prioritized composite endpoints (eg, components are assessed in order of clinical importance). Power and sample size estimation for the FS test, however, are generally done via simulation studies. This simulation approach can be extremely computationally burdensome, compounded by increasing number of composite endpoints and with increasing sample size. Here we propose an analytical solution to calculate power and sample size for commonly encountered two-component hierarchical composite endpoints. The power formulas are derived assuming underlying distributions in each of the component outcomes on the population level, which provide a computationally efficient and practical alternative to the standard simulation approach. Monte Carlo simulation results demonstrate that performance of the proposed power formulas are consistent with that of the simulation approach, and have generally desirable objective properties including robustness to mis-specified distributional assumptions. We demonstrate the application of the proposed formulas by calculating power and sample size for the Transthyretin Amyloidosis Cardiomyopathy Clinical Trial.

Refractive Outcomes of Non-Toric and Toric Intraocular Lenses in Mild, Moderate and Advanced Keratoconus: A Systematic Review and Meta-Analysis.

Background: To perform a systematic review and meta-analysis of the refractive outcomes of non-toric and toric intraocular lenses (IOLs) in keratoconus (KC) using different IOL power calculation formulas. Methods: A systematic search was conducted to identify studies that report on refractive outcomes of different IOL power calculation formulas in KC patients undergoing cataract surgery. Inclusion criteria were primary posterior chamber non-toric and toric monofocal intraocular lens implantation, data on the degree of KC, explicit mention of the formula used for each stage of KC, and the number of eyes in each category. We calculated and compared the absolute and mean prediction errors, percentage of eyes within 0.5 D and 1 D from target, and the weighted absolute prediction errors of IOL formulas, all were given for KC degrees I–III. Results: The bibliographic search yielded 582 studies published between 1996 and 2020, 14 of which (in total 456 eyes) met the criteria: three studies on non-toric IOL (98 eyes), eight studies on toric IOLs (98 eyes) and three studies of unknown separation between non-toric and toric IOLs (260 eyes). The lowest absolute prediction error (APE) for mild, moderate, and advanced KC was seen with Kane’s IOL power formula with keratoconus adjustment. The APE for the top five IOL power formulas ranged 0.49–0.73 diopters (D) for mild (83–94%) of eyes within 1 D from the target), 1.08–1.21 D for moderate (51–57% within 1 D), and 1.44–2.86 D for advanced KC (12–48% within 1 D). Conclusions: Cataract surgery in eyes with mild-to-moderate KC generally achieves satisfactory postoperative refractive results. In patients with advanced KC, a minority of the eyes achieved spherical equivalent refraction within 1 D from the target. The Kane’s formula with keratoconus adjustment showed the best results in all KC stages.

Accuracy of newer intraocular lens power formulas in short and long eyes using sum-of-segments biometry.

To analyze the accuracy of newer intraocular lens power formulas in long and short eyes measured using the sum-of-segments biometry. Private practice, Lynwood, California. Retrospective observational study. 595 patients scheduled for cataract surgery had their eyes measured using the sum-of-segments biometry. The expected residual refractions were calculated using Barrett Universal II (B II), Barrett True Axial Length (BTAL), Emmetropia Verifying Optical (EVO), Hill-RBF, Hoffer QST, Holladay 2, Holladay 2-NLR, K6, Kane, Olsen, PEARL-DGS, T2, and VRF formulas and compared with the traditional Haigis, Hoffer Q, Holladay 1, and SRK/T formulas. In the 102 long eyes, all new formulas had a mean absolute error (MAE) equal or lower than the traditional formulas, ranging from 0.29 to 0.32 diopter (D). In the 78 short eyes, BTAL, EVO, Hoffer QST, K6, Olsen, and PEARL-DGS formulas had the lowest MAE (0.33 D, 0.33 D, 0.31 D, 0.36 D, 0.32 D, and 0.32 D, respectively), whereas all traditional formulas exceeded 0.36 D. All new formulas performed equal or better than the traditional formulas with the sum-of-segments biometry. The best overall results in the short and long eyes as well as in the very short and very long eyes were noted with the BTAL, EVO, Hoffer QST, K6, Olsen, and PEARL-DGS formulas, closely followed by the B II and Kane formulas.

A nanovaccine for antigen self-presentation and immunosuppression reversal as a personalized cancer immunotherapy strategy.

The strategy of combining a vaccine with immune checkpoint inhibitors has been widely investigated in cancer management, but the complete response rate for this strategy is still unresolved. We describe a genetically engineered cell membrane nanovesicle that integrates antigen self-presentation and immunosuppression reversal (ASPIRE) for cancer immunotherapy. The ASPIRE nanovaccine is derived from recombinant adenovirus-infected dendritic cells in which specific peptide-major histocompatibility complex class I (pMHC-I), anti-PD1 antibody and B7 co-stimulatory molecules are simultaneously anchored by a programmed process. ASPIRE can markedly improve antigen delivery to lymphoid organs and generate broad-spectrum T-cell responses that eliminate established tumours. This work presents a powerful vaccine formula that can directly activate both native T cells and exhausted T cells, and suggests a general strategy for personalized cancer immunotherapy.

Management of refractive surprise after phacoemulsification due to a decentered laser-assisted in situ keratomileusis zone

A 39-year-old male with prior history of having undergone laser-assisted in situ keratomileusis (LASIK) in both eyes was referred for management of refractive surprise of +5.0 diopter following phacoemulsification with intraocular lens (IOL) implantation in the left eye. The IOL power was re-calculated using post-LASIK IOL power formulae, but it did not differ significantly from that of the implanted IOL. Topography in the left eye showed decentration of the laser ablation zone and mild ectasia. An IOL exchange was performed in the following steps: IOL extraction, postoperative aphakic refraction to calculate IOL power, and IOL implantation. Postoperatively, there was no refractive surprise. In the right eye, the IOL power was calculated using post-LASIK IOL power formulae, which did not result in postoperative refractive surprise. Our experience highlights the efficiency of aphakic refraction over post-LASIK IOL power formulae in predicting IOL power in eyes with decentered laser ablations.

Accuracy of intraocular lens power formulas for eyes with scleral-sutured intraocular lenses in congenital ectopia lentis

To compare the accuracy of intraocular lens (IOL) power calculation formulas in eyes with congenital ectopia lentis (CEL) that underwent scleral-fixated IOL implantation. Zhongshan Ophthalmic Center, Guangzhou, China. Retrospective consecutive case-series study. 158 eyes from 158 patients diagnosed from December 12, 2017, to November 16, 2020, with CEL and undergoing a lensectomy and scleral fixation of a Rayner 920H or 970C model IOL were retrospectively reviewed. The prediction errors (PEs) of the spherical equivalent of 8 formulas, Barrett Universal II (BUII), Emmetropia Verifying Optical (EVO), Haigis, Hoffer Q, Holladay 1, Kane, Hill-RBF 3.0, and SRK/T, were compared. For CEL patients with scleral-sutured IOL, all 8 formulas yielded myopic PEs without constant optimization. After such optimization, the performance of each formula ranked by median absolute error (MedAE) from the lowest to highest in diopter (D) was as follows: SRK/T (0.47), EVO (0.48), Kane (0.52), BUII (0.53), Hoffer Q (0.58), Holladay 1 (0.59), Haigis (0.61), and Hill-RBF 3.0 (0.62) formulas. The EVO and SRK/T formulas had the highest prediction accuracy concerning the percentage of cases within ±0.50 D and ±1.00 D range of PE in eyes that experienced scleral-sutured IOL surgery, respectively. All formulas before constant optimization produced myopic PEs. After optimization, the SRK/T and EVO formulas had the lowest MedAE and the highest percentage of PE in the range within ±0.50 D for CEL patients with scleral-sutured IOL implantations.

A PLL-free control strategy for flexible DC transmission systems

The grid-connected inverter needs to know the phase information of the grid voltage. The traditional method is to use the phase-locked loop (PLL) to capture the phase of the grid. However, the PLL takes some time to capture the phase and affects the stability of the grid-connected inverter. Based on this, this paper proposes a vector control strategy without PLL. Firstly, the virtual vector axis is constructed, and the grid voltage is transformed as the reference phase angle. Then the instantaneous power formula in this case is derived. The corresponding control block diagram is constructed. The method reduces the coordinate transformation operation and simplifies the control structure while ensuring the stability of the control system. The simulation results under MATLAB/Simulink show that the control effect of this method is better than that of the PLL vector control strategy, and the method has smaller computational complexity, less resources and more cost savings.

Sample size calculation for the augmented logrank test in randomized clinical trials.

In randomized clinical trials, incorporating baseline covariates can improve the power in hypothesis testing for treatment effects. For survival endpoints, the Cox proportional hazards model with baseline covariates as explanatory variables can improve the standard logrank test in power. Although this has long been recognized, this adjustment is not commonly used as the primary analysis and instead the logrank test followed by the estimation of the hazard ratio between treatment groups is often used. By projecting the score function for the Cox proportional hazards model onto a space of covariates, the logrank test can be more powerful. We derive a power formula for this augmented logrank test under the same setting as the widely used power formula for the logrank test and propose a simple strategy for sizing randomized clinical trials utilizing historical data of the control treatment. Through numerical studies, the proposed procedure was found to have the potential to reduce the sample size substantially as compared to the standard logrank test. A concern to utilize historical data is that those might not reflect well the data structure of the study to design and then the sample size calculated might not be accurate. Since our power formula is applicable to datasets pooled across the treatment arms, the validity of the power calculation at the design stage can be checked in blind reviews.

TINJAUAN KEBIJAKAN DESENTRALISASI PENDIDIKAN DI INDONESIA

In Indonesian national education, the concept of decentralization is still a relatively recent one. It has been mandated by the government in Indonesia's Education Law number 20 of 2003. It is the goal of this research to examine the strategic concerns surrounding Indonesia's education decentralization strategy and then develop alternate strategies for putting them into action. The development of decentralized education is supposed to provide more space for stakeholders. Descriptive analysis and a qualitative method are used in this investigation. Researchers found that Indonesia's main challenges in implementing education policies are in quality control, financing, and teacher professionalism. This can serve as a guide for both central and regional governments to create powerful formulas for making appropriate policies so they can improve education quality. It is impossible to apply the decentralization concept without taking into consideration political and sociological considerations.