bluuebunny/crossref_metadata_2025 huggingface dataset:
Cross-sectional association between social and demographic factors and disease activity in rheumatoid arthritis
Authors: Zhu Lei , Moreland Larry W. , Ascherman Dana
Published: January 2024

Background

This study aimed to assess the association between social factors, demographic parameters, and disease activity among rheumatoid arthritis (RA) patients.

Methods

The University of Pittsburgh Rheumatoid Arthritis Comparative Effectiveness Research (RACER) registry was used for this study and included patients meeting 1987 ACR criteria for RA enrolled between 2010–2015. The registry collected clinical and laboratory data at each visit, permitting the calculation of disease activity measures that included Disease Activity 28-C Reactive Protein (DAS28-CRP). The current study was conducted as a cross-sectional study in which baseline data were used to construct multiple logistic regression models assessing the relationship between disease activity measures (DAS28-CRP), functional capacity (health assessment questionnaire (HAQ)), selected demographic and social factors (occupation, education, income, marital status, race, gender, age, and BMI), and clinical/laboratory variables.

Results

The analyses included 729 patients with baseline DAS28-CRP and social/demographic data. The mean age at enrollment was 59.5 (Standard Deviation (SD) = 12.7) years, 78% were female, and the median RA disease duration was 9.8 (Interquartile Range (IQR): 3.7, 19.1) years. We dichotomized the DAS28-CRP score and defined scores above or below 3.1 as high versus low RA disease activity. Most patients with high RA disease activity (N = 326, 45%) had less than a college degree (70%), were not working/retired/disabled (71%), and had an annual income under $50 K (55%). We found that higher body mass index (BMI) (Odds Ratio (OR) = 1.04, 95% CI: 1.01—1.08), longer disease duration (> 2 and < 10 years versus ≤ 2 years of disease) (OR = 0.45, 95% CI: 0.25—0.78), and being retired (OR = 1.74, 95% CI: 1.02—2.98) were associated with RA disease activity.

Conclusion

Increased RA activity may be associated with various social factors, potentially leading to more severe and debilitating disease outcomes. These findings provide evidence to support efforts to monitor disparities and achieve health equity in RA.
Comparative effectiveness of abatacept versus TNF inhibitors in rheumatoid arthritis patients who are ACPA and shared epitope positive
Authors: Harrold Leslie R. , Wittstock Keith , Kelly Sheila , Han Xue , Zhuo Joe , Schrader Amy , Middaugh Nicole , Moore Page C. , Khaychuk Vadim
Published: January 2024

Background

The HLA-DRB1 shared epitope (SE) is a risk factor for the development of rheumatoid arthritis (RA) and the production of anti-citrullinated protein antibodies (ACPAs) in RA patients. Our objective was to examine the real-world effectiveness of abatacept versus tumor necrosis factor inhibitors (TNFi) in patients with RA who were SE and anti-cyclic citrullinated peptide antibody (anti-CCP3) positive.

Methods

Abatacept or TNFi initiators who were SE + and anti-CCP3+ (> 20 U/mL) at or prior to treatment and had moderate or high CDAI score (> 10) at initiation were identified. The primary outcome was mean change in CDAI score over six months. Analyses were conducted in propensity score (PS)-trimmed and -matched populations overall and a biologic-experienced subgroup. Mixed-effects models were used.

Results

In the overall PS-trimmed (abatacept, n = 170; TNFi, n = 157) and PS-matched cohorts (abatacept, n = 111; TNFi, n = 111), there were numerically greater improvements in mean change in CDAI between abatacept and TNFi but were not statistically significant. Similar trends were seen for biologic-experienced patients, except that statistical significance was reached for mean change in CDAI in the PS-trimmed cohort (abatacept, 12.22 [95% confidence interval (95%CI) 10.13 to 14.31]; TNFi, 9.28 [95%CI 7.08 to 11.48]; p = 0.045).

Conclusion

In this real world cohort, there were numerical improvements in efficacy outcomes with abatacept over TNFi in patients with RA who were SE + and ACPA+, similar to results from a clinical trial population The only statistically significant finding after adjusting for covariates was greater improvement in CDAI with abatacept versus TNFi in the bio-experienced PS-trimmed cohort..
A unique revolutionary eco-friendly spectrophotometric technique for solving the spectral overlap in the determination of carvedilol and ivabradine in their binary combination: stability study
Authors: El Fiky Haitham A. , Abd El Ghany Maha F. , Badawey Amr M. , Fares N. V. , Ahmed Dina A.
Published: January 2024

Background

Carivalan® dosage form containing carvedilol and ivabradine is widely indicated for patients with stable angina. Three precise, eco-friendly and reproducible spectrophotometric techniques were created for resolving the researched drugs in their mixtures using zero and/or ratio spectra. Technique I is a factorized dual wavelength coupled with spectrum subtraction (FDW-SS), technique II is a ratio difference, and technique III is a constant center coupled with spectrum subtraction (CC-SS). Moreover, CAR and IVA were simultaneously determined in the existence of their oxidative degradation products exploiting the newly developed induced tripartite amplitude difference coupled with ratio subtraction (ITAD-RS) technique.

Results

The calibration curves for CAR and IVA showed linearity within 3.0–30.0 µg/ml, each. Techniques' precision, accuracy, and linearity ranges were resolved and validated in harmony with ICH guidelines. Additionally, the specificity was examined by examining created combinations of the proposed drugs with LOD of 0.258 and 0.290 for CAR, while for IVA 0.272 and 0.204.

Conclusion

These techniques were used to determine the presence of the provided drugs in Carivalan® tablets. There is statistical comparison between the found results of the offered spectrophotometric techniques and the previously reported ones with no discernible variance in the acquired results.
Raising the Bar for Real-World Data in Oncology: Approaches to Quality Across Multiple Dimensions
Authors: Castellanos Emily H. , Wittmershaus Brett K. , Chandwani Sheenu
Published: January 2024

PURPOSE

Electronic health record (EHR)–based real-world data (RWD) are integral to oncology research, and understanding fitness for use is critical for data users. Complexity of data sources and curation methods necessitate transparency into how quality is approached. We describe the application of data quality dimensions in curating EHR-derived oncology RWD.

METHODS

A targeted review was conducted to summarize data quality dimensions in frameworks published by the European Medicines Agency, The National Institute for Healthcare and Excellence, US Food and Drug Administration, Duke-Margolis Center for Health Policy, and Patient-Centered Outcomes Research Institute. We then characterized quality processes applied to curation of Flatiron Health RWD, which originate from EHRs of a nationwide network of academic and community cancer clinics, across the summarized quality dimensions.

RESULTS

The primary quality dimensions across frameworks were relevance (including subdimensions of availability, sufficiency, and representativeness) and reliability (including subdimensions of accuracy, completeness, provenance, and timeliness). Flatiron Health RWD quality processes were aligned to each dimension. Relevancy to broad or specific use cases is optimized through data set size and variable breadth and depth. Accuracy is addressed using validation approaches, such as comparison with external or internal reference standards or indirect benchmarking, and verification checks for conformance, consistency, and plausibility, selected on the basis of feasibility and criticality of the variable to the intended use case. Completeness is assessed against expected source documentation; provenance by recording data transformation, management procedures, and auditable metadata; and timeliness by setting refresh frequency to minimize data lags.

CONCLUSION

Development of high-quality, scaled, EHR-based RWD requires integration of systematic processes across the data lifecycle. Approaches to quality are optimized through knowledge of data sources, curation processes, and use case needs. By addressing quality dimensions from published frameworks, Flatiron Health RWD enable transparency in determining fitness for real-world evidence generation.
Locoregional Breast Cancer Recurrence in the European Organisation for Research and Treatment of Cancer 10041/BIG 03-04 MINDACT Trial: Analysis of Risk Factors Including the 70-Gene Signature
Authors: Alaeikhanehshir Sena , Ajayi Taiwo , Duijnhoven Frederieke H. , Poncet Coralie , Olaniran Ridwan O. , Lips Esther H. , van 't Veer Laura J. , Delaloge Suzette , Rubio Isabel T. , Thompson Alastair M. , Cardoso Fatima , Piccart Martine , Rutgers Emiel J.T.
Published: January 2024

PURPOSE

A number of studies are currently investigating de-escalation of radiation therapy in patients with a low risk of in-breast relapses on the basis of clinicopathologic factors and molecular tests. We evaluated whether 70-gene risk score is associated with risk of locoregional recurrence (LRR) and estimated 8-year cumulative incidences for LRR in patients with early-stage breast cancer treated with breast conservation.

METHODS

In this exploratory substudy of European Organisation for Research and Treatment of Cancer 10041/BIG 03-04 MINDACT trial, we evaluated women with a known clinical and genomic 70-gene risk score test result and who had breast-conserving surgery (BCS). The primary end point was LRR at 8 years, estimated by cumulative incidences. Distant metastasis and death were considered competing risks.

RESULTS

Among 6,693 enrolled patients, 5,470 (81.7%) underwent BCS, of whom 98% received radiotherapy. At 8-year follow-up, 189 patients experienced a LRR, resulting in an 8-year cumulative incidence of 3.2% (95% CI, 2.7 to 3.7). In patients with a low-risk 70-gene signature, the 8-year LRR incidence was 2.7% (95% CI, 2.1 to 3.3). In univariable analysis, adjusted for chemotherapy, five of 12 variables were associated with LRR, including the 70-gene signature. In multivariable modeling, adjuvant endocrine therapy and to a lesser extent tumor size and grade remained significantly associated with LRR.

CONCLUSION

This exploratory analysis of the MINDACT trial estimated an 8-year low LRR rate of 3.2% after BCS. The 70-gene signature was not independently predictive of LRR perhaps because of the low number of events observed and currently cannot be used in clinical decision making regarding LRR. The overall low number of events does provide an opportunity to design trials toward de-escalation of local therapy.
Elasticity, plasticity and screening in amorphous solids: A short review
Authors: Kumar Avanish , Procaccia Itamar
Published: January 2024

The aim of this short review is to summarize the developing theory aimed at describing the effect of plastic events in amorphous solids on its emergent mechanics. Experiments and simulations present anomalous mechanical response of amorphous solids where quadrupolar plastic events collectively induce distributed dipoles that are analogous to dislocations in crystalline solids. The novel theory is described, and a number of pertinent examples are provided, including the comparison of theoretical prediction to simulations or experiments.
State-to-State Variation in Medicaid Reimbursement for Neurosurgical Procedures: Implications for Healthcare Access in Vulnerable Populations
Authors: Rallo Michael S. , Berke Chandler N. , Shaw Thomas C. , Bunch Jaclyn A. , Menger Richard P.
Published: January 2024

BACKGROUND AND OBJECTIVES:

Medicaid payment for healthcare services traditionally reimburses less than Medicare and commercial insurance. This disparity in reimbursement seems to be an important driver of limited access to care among Medicaid beneficiaries. This study seeks to examine the degree of variation in Medicaid and Medicare reimbursement for the most common neurosurgical current procedural terminology codes and determine its potential impact on provider accessibility.

METHODS:

In this cross-sectional study, maximum allowed physician reimbursement fees for 20 common neurosurgical codes reported in the literature were obtained from the 2022 Medicare Physician Fee Schedule and individual state Medicaid Fee-for-Service Schedules. The Medicaid-Medicare Index (MMI), which measures Medicaid reimbursement as a fraction of Medicare allowed amounts, was calculated for each procedure across 49 states and the District of Columbia. Lower MMI indicates a greater disparity, or “discount,” between Medicaid and Medicare reimbursement. The proportion of providers accepting new Medicaid patients and total Medicaid enrollment were compared across states as a function of MMI.

RESULTS:

The average national MMI was 0.79, with a range of 0.37 in NY/NJ to 1.43 in NE. Maximum allowed amounts for Medicare reimbursement (coefficient of variation = 0.09) were less variable than those for Medicaid (coefficient of variation = 0.26, P < .01). The largest absolute disparity was observed for intracranial aneurysm clipping in NY, where the maximum Medicaid reimbursement is $3496.52 less than that of Medicare. Higher MMI was associated with a significantly larger proportion of providers accepting new Medicaid patients (R2 = 0.43, P < .01). Moreover, MMI varied inversely with the number of Medicaid beneficiaries (R2 = 0.12, P = .01).

CONCLUSION:

Medicaid reimbursement varies between states reflecting the disparate methods of fee schedule calculation. Lower reimbursement is associated with more limited provider enrollment, especially in states with a greater number of beneficiaries.
Interplay of Zeb2a, Id2a and Batf3 regulates microglia and dendritic cell development in the zebrafish brain
Authors: Nguyen Linh Thi My , Hassan Shaoli , Pan Hongru , Wu Shuting , Wen Zilong
Published: January 2024

In vertebrates, the central nervous system (CNS) harbours various immune cells, including parenchymal microglia, perivascular macrophages and dendritic cells, which act in coordination to establish an immune network to regulate neurogenesis and neural function, and to maintain the homeostasis of the CNS. Recent single cell transcriptomic profiling has revealed that the adult zebrafish CNS contains microglia, plasmacytoid dendritic cells (pDCs) and two conventional dendritic cells (cDCs), ccl35+ cDCs and cnn3a+cDCs. However, how these distinct myeloid cells are established in the adult zebrafish CNS remains incompletely defined. Here, we show that the Inhibitor of DNA binding 2a (Id2a) is essential for the development of pDCs and cDCs but is dispensable for the formation of microglia, whereas the Basic leucine zipper transcription factor ATF-like 3 (Batf3) acts downstream of id2a and is required exclusively for the formation of the cnn3a+ cDC subset. In contrast, the Zinc finger E-box-binding homeobox 2a (Zeb2a) promotes the expansion of microglia and inhibits the DC specification, possibly through repressing id2a expression. Our study unravels the genetic networks that govern the development of microglia and brain-associated DCs in the zebrafish CNS.
Fibroblast growth factor-induced lens fiber cell elongation is driven by the stepwise activity of Rho and Rac
Authors: Sugiyama Yuki , Reed Daniel A. , Herrmann David , Lovicu Frank J. , Robinson Michael L. , Timpson Paul , Masai Ichiro
Published: January 2024

The spheroidal shape of the eye lens is crucial for precise light focusing onto the retina. This shape is determined by concentrically aligned, convexly elongated lens fiber cells along the anterior and posterior axis of the lens. Upon differentiation at the lens equator, the fiber cells increase in height as their apical and basal tips migrate towards the anterior and posterior poles, respectively. The forces driving this elongation and migration remain unclear. We found that, in the mouse lens, membrane protrusions or lamellipodia are observed only in the maturing fibers undergoing cell curve conversion, indicating that lamellipodium formation is not the primary driver of earlier fiber migration. We demonstrated that elevated levels of fibroblast growth factor (FGF) suppressed the extension of Rac-dependent protrusions, suggesting changes in the activity of FGF controlling Rac activity, switching to lamellipodium-driven migration. Inhibitors of ROCK, myosin and actin reduced the height of both early and later fibers, indicating that elongation of these fibers relies on actomyosin contractility. Consistent with this, active RhoA was detected throughout these fibers. Given that FGF promotes fiber elongation, we propose that it does so through regulation of Rho activity.
The Drosophila tumour suppressor Lgl and Vap33 activate the Hippo pathway through a dual mechanism
Authors: Portela Marta , Mukherjee Swastik , Paul Sayantanee , La Marca John E. , Parsons Linda M. , Veraksa Alexey , Richardson Helena E.
Published: January 2024

The tumour suppressor, Lethal (2) giant larvae [Lgl; also known as L(2)gl], is an evolutionarily conserved protein that was discovered in the vinegar fly Drosophila, where its depletion results in tissue overgrowth and loss of cell polarity. Lgl links cell polarity and tissue growth through regulation of the Notch and the Hippo signalling pathways. Lgl regulates the Notch pathway by inhibiting V-ATPase activity via Vap33. How Lgl regulates the Hippo pathway was unclear. In this current study, we show that V-ATPase activity inhibits the Hippo pathway, whereas Vap33 acts to activate Hippo signalling. Vap33 physically and genetically interacts with the actin cytoskeletal regulators RtGEF (Pix) and Git, which also bind to the Hippo protein (Hpo) and are involved in the activation of the Hippo pathway. Additionally, we show that the ADP ribosylation factor Arf79F (Arf1), which is a Hpo interactor, is involved in the inhibition of the Hippo pathway. Altogether, our data suggest that Lgl acts via Vap33 to activate the Hippo pathway by a dual mechanism: (1) through interaction with RtGEF, Git and Arf79F, and (2) through interaction and inhibition of the V-ATPase, thereby controlling epithelial tissue growth.
DNA-PKcs-mediated transcriptional regulation of TOP2B drives chemoresistance in acute myeloid leukemia
Authors: Mishra Saket V. , Banerjee Archisman , Sarkar Debashmita , Thangarathnam Vishnuvarthan , Bagal Bhausaheb , Hasan Syed K. , Dutt Shilpee
Published: January 2024

Anthracyclines, topoisomerase II enzyme poisons that cause DNA damage, are the mainstay of acute myeloid leukemia (AML) treatment. However, acquired resistance to anthracyclines leads to relapse, which currently lacks effective treatment and is the cause of poor survival in individuals with AML. Therefore, the identification of the mechanisms underlying anthracycline resistance remains an unmet clinical need. Here, using patient-derived primary cultures and clinically relevant cellular models that recapitulate acquired anthracycline resistance in AML, we have found that GCN5 (also known as KAT2A) mediates transcriptional upregulation of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) in AML relapse, independently of the DNA-damage response. We demonstrate that anthracyclines fail to induce DNA damage in resistant cells, owing to the loss of expression of their target enzyme, TOP2B; this was caused by DNA-PKcs directly binding to its promoter upstream region as a transcriptional repressor. Importantly, DNA-PKcs kinase activity inhibition re-sensitized AML relapse primary cultures and cells resistant to mitoxantrone, and abrogated their tumorigenic potential in a xenograft mouse model. Taken together, our findings identify a GCN5–DNA-PKcs–TOP2B transcriptional regulatory axis as the mechanism underlying anthracycline resistance, and demonstrate the therapeutic potential of DNA-PKcs inhibition to re-sensitize resistant AML relapse cells to anthracycline.
Media Attention and Event-Based Grouping of Stocks: An Examination of Stocks Hyped by Media Outlets as Benefiting from the Olympics
Authors: Dechow Patricia , Lawrence Alastair , Luo Mei , Stamenov Ventsislav
Published: January 2024

We examine five summer Olympics and identify stocks that media outlets hype as benefiting from the Olympics (Olympic stocks). There is a seven-year period from the time that a country first learns it has won the Olympic bid to the start of the games (Olympic time period). We predict that the excitement of the Olympics along with the greater media attention impacts the valuation and risk of Olympic stocks. Consistent with this prediction, we show that Olympic stocks earn higher returns than their matched counterparts and comove more strongly with each other over the Olympic time period. Olympic stocks also exhibit increases in trading volume and stock volatility on days when media outlets have stories linking the firm to the Olympic Games. However, we find no evidence that the Olympic Games translate into stronger fundamentals for Olympic firms or stronger fundamental comovements. These findings suggest that investors are not purchasing the stocks based on an analysis of fundamentals, but are purchasing them based on their Olympic attribute. To confirm that event-based groupings occur in other settings, we show that comovement increases for stocks classified by the media as “stay-at-home” stocks at the start of the COVID-19 pandemic.

This paper was accepted by Eric So, accounting.

Supplemental Material: The online appendix is available at https://doi.org/10.1287/mnsc.2021.02218 .
Paid Priority in Service Systems: Theory and Experiments
Authors: Frazelle Andrew E. , Katok Elena
Published: January 2024

Problem definition: Motivated by the prevalence of paid priority programs in practice, we study a service provider operating a system in which customers have random waiting costs and choose between two queues: regular (no cost) or priority (for a fee). We also consider a mechanism by which the provider redistributes a portion of priority revenue to compensate regular-queue customers for their longer waits. Methodology/results: To determine the waiting-cost-dependent equilibrium priority purchasing strategies, we establish structural results at a sample-path level and prove that they generalize. In models both with and without compensation, the equilibrium exhibits a cost-dependent, increasing-threshold structure. We also prove that compensation entails fewer priority purchases because compensating regular-queue customers makes priority less attractive. We then analyze system-wide performance. Despite the fewer priority purchases, for a fixed (low) priority fee, compensation can actually reduce equilibrium aggregate waiting cost by filtering low-waiting-cost customers out of the priority queue; however, this finding does not hold when comparing at the optimal fees. We then test our models in the laboratory. Key behavioral regularities are that low-cost subjects are overrepresented (underrepresented) in the priority (regular) queue compared with equilibrium, and subjects with low and high waiting costs tend to overbuy priority at high fees. Managerial implications: Our theoretical and behavioral results guide service providers in managing priority service systems. First, we find that compensation does not provide short-term performance benefits. Second, our experiments reveal that suboptimal customer decisions partially prevent efficient reordering of customers by waiting cost, leading to higher aggregate waiting cost than the equilibrium predicts, but still lower than under first-come, first-serve service. Finally, because customers tolerate higher fees than they should, a revenue-maximizing provider can set a higher priority fee and extract more revenue than it could if customers acted rationally.

Funding: This work was supported by the Center and Laboratory for Behavioral Operations and Economics at the Naveen Jindal School of Management at The University of Texas at Dallas.

Supplemental Material: The online appendix is available at https://doi.org/10.1287/msom.2021.0387 .
CELESTE, A BONECA COM OLHOS DE ESPERANÇA: UM GESTO DE CONSTRUÇÃO IDENTITÁRIA
Authors: Cuna Aurelio Jose
Published: January 2024

O objectivo desta reflexão é fazer uma recensão crítica do mais recente livro de Sónia Sultuane, intitulado Celeste, a boneca com olhos de esperança. Publicada em 2017, a obra conta uma história de vida partilhada por três personagens: a Joana, a boneca Celeste e os meninos com problemas de vista. Dessa história partilhada, através de acções, diálogos e monólogos, irrompem teias de identidade. Daí o tema do presente estudo, cujo desenvolvimento consistiu na análise das vozes do narrador e das personagens. O estudo tenta mostrar que o conto, um género literário que se caracteriza por ser breve, propicia a apreensão rápida da mensagem pelos leitores, sobretudo, os de menor idade. No texto analisado, a principal mensagem é a sugestão de identidade multicultural.
Relationship between evaluation concern perfectionism and career stress : parallel multiple mediating effect of career decision- making self-efficacy and academic delay
Authors: Lee Gieeun , Ahn Seyun
Published: January 2024

This study was conducted for the purpose of preparing a counseling intervention plan in the career and academic fields of college students related to career stress by verifying the parallel multiple mediating effect of career decision-making self-efficacy and academic delay in the relationship between evaluation concern perfectionism and career stress. To this end, a survey was conducted on 210 college students sampled through online communities using Google, of which 203 data were used for analysis. The collected data were analyzed using SPSS 25.0 and PROCESS Macro 3.5. The results of the study are as follows. First, as a result of correlation analysis, it was found that perfectionism of evaluation concerns had a positive correlation with career stress, career decision-making self-efficacy, and academic delay. Career stress was negatively correlated with career decision-making self-efficacy and positively correlated with academic delay. There was a negative correlation between career decision-making self-efficacy and academic delay. Second, it was found that career decision-making self-efficacy and academic delay had a partial mediating effect in the relationship between evaluation concern perfectionism and career stress. Based on the results of this study, limitations and suggestions for follow-up studies were discussed.
Sleep Preferences and Chronotype Traits Impact on Academic Performance Among University Students
Authors: Figueiredo Sandra , Kulari Genta
Published: January 2024

Due to irregular daytime routines, chronotype changes, side jobs and exam periods after the COVID-19 pandemic, university students are trying to find new balances in their everyday life. The aim of the present study is to analyze the impact of daytime chronotype and hour preferences for the circadian rhythm on academic achievement among university students, considering their sleep habits and class frequencies in daytime and nighttime classes. Furthermore, this study aimed to analyze the differences in chronotype preferences with regard to age, sex, and academic schedule students are attending. A sample of 87 university second-year Psychology and Management students attending the academic year 2021/2022 after the governmental relief measures of the COVID-19 pandemic completed a 13-item questionnaire on sleep habits and preferences. Further variables encompassed sleep behaviors, such as age, sex, daytime and nighttime classes, as well as academic achievement. The results of the study showed that university students had a higher preference for the morningness type. Additionally, chronotype traits explained 30% (values from regression analysis) of academic achievement but did not directly impact academic results. The sleep-wake cycle diverged among age groups because the youngest participants (19–21 years old) and older participants (35–44 years old) reported higher academic scores during the first semester and the full academic year. No significant differences were identified with respect to sex. There is a lack of literature explaining the effect of sleep hours on academic achievement among students after stay-at-home rules during the COVID-19 pandemic. Thus, it is imperative to understand the difficulties students face with regard to their studying hours, working shifts, and daytime or nighttime classes to create a sustainable university system that attends to students’ needs and necessities.
Exciting space-time surface plasmon polaritons by irradiating a nanoslit structure
Authors: Ichiji Naoki , Yessenov Murat , Schepler Kenneth L. , Abouraddy Ayman F. , Kubo Atsushi
Published: January 2024

Space-time (ST) wave packets are propagation-invariant pulsed optical beams that travel freely in dielectrics at a tunable group velocity without diffraction or dispersion. Because ST wave packets maintain these characteristics even when only one transverse dimension is considered, they can realize surface-bound waves (e.g., surface plasmon polaritons at a metal-dielectric interface, which we call ST-SPPs) that have the same unique characteristics as their freely propagating counterparts. However, because the spatiotemporal spectral structure of ST-SPPs is key to their propagation invariance on the metal surface, their excitation methodology must be considered carefully. Using finite-difference time-domain simulations, we show that an appropriately synthesized ST wave packet in free space can be coupled to an ST-SPP via a single nanoscale slit inscribed in the metal surface. Our calculations confirm that this excitation methodology yields surface-bound ST-SPPs that are localized in all dimensions (and can thus be considered as plasmonic “bullets”), which travel rigidly at the metal-dielectric interface without diffraction or dispersion at a tunable group velocity.
Semi-analytical models to engineer a metalens composed of various meta-atoms
Authors: Bouillon Christopher , Borne Jeck , Ouellet-Oviedo Elias , Thibault Simon
Published: January 2024

We developed semi-analytical models to efficiently and rapidly obtain the propagation characteristics of square nanopillar and nanoring meta-atoms. We show that such analytical models can predict the output phase profile and chromatic behavior of a metasurface composed of various meta-atoms. We found that said models are accurate enough so that an optical designer can use them as a quick and pertinent alternative to tedious and time-consuming FDTD simulations. A mixed array of three different nanostructures combining square nanopillars, nanorings, and nanorods has been designed and compared to FDTD simulation with good conformity. Thus, we show the pertinence of the two semi-analytical models and the possibilities granted by the mixing of various meta-atoms. This work allows for more flexibility and design freedom for quick modeling of metasurface properties and adds to previous models developed in our research group.
High-efficient and low-loss hybrid Si/VO2 absorption modulator electrically driven by graphene electrodes
Authors: Liu Chang , Fei Yedeng , Xu Yin , Ni Yi
Published: January 2024

The phase change material vanadium dioxide (VO2) is suitable for building high-efficiency light modulators due to the different absorption efficiency of light in metallic and insulating states. The structure of an electro-absorption modulator based on VO2 and graphene proposed in this paper is formed by two layers of single-layer graphene wrapped around VO2, with a silicon waveguide in the middle and silica on both sides as the main path for light transmission. The input light of TE mode is limited to the SiO2 layer on both sides to increase the contact area with VO2 layers, which make it almost impossible to pass through when the metal electrode is connected to an external bias voltage and VO2 is in the metallic state. On the contrary, the input light passes through the main path of the modulation region with low loss without bias voltage. Finally, the modulator proposed in this paper has achieved a high extinction ratio of 27.3 dB and a low insertion loss of 0.66 dB (when VO2 is in insulating state) at a single wavelength of 1550 nm when the device length is 2 µm. In addition, the bias voltage of the modulator is 1.1 V with the modulation speed at 200 MHz, and the energy consumption is only 8.3083 fJ/bit at work, which is an ideal choice for photonic integrated systems today.
Hyperbolic phonon-plasmon polaritons in a hBN-graphene van der Waals structure
Authors: Bludov Yu. V. , Bahamon D. A. , Peres N. M. R. , de Matos C. J. S.
Published: January 2024

In this paper, a thorough theoretical study of a class of collective excitations, dubbed hyperbolic surface phonon-plasmon polaritons, is performed. These types of light-matter excitations are shown to have unique properties that allow to explore them both as the basis of ultra-sensitive devices to the dielectric nature of their surroundings. The system is a van der Waals heterostructure–a layered metamaterial, composed of different 2D materials in direct contact one with another, namely, graphene ribbons and hexagonal boron nitride slabs of nanometric size. In the paper, we discuss the spectrum of these classes of excitations, the associated electromagnetic fields, the sensitivity to the dielectric function of its surroundings, and the absorption spectrum. All of this is accomplished using an analytical model that considerably diminishes the computational burden, as well as elucidates the underling physical mechanism of the excitations supported by the device.
Study of fixing holographic gratings in Bi2TeO5 photorefractive crystals
Authors: de Oliveira Ivan , Carvalho Jesiel Freitas
Published: January 2024

Experimental results on the diffraction efficiency of fixed holograms in undoped Bi2TeO5 are presented. Gratings were recorded at room temperature, and using a 532 nm wavelength laser light, the diffraction efficiency of the fixed grating was found to be dependent on the grating’s spacing and recording time.
Generation of ultra-intense vortex laser from a binary phase square spiral zone plate
Authors: Zhang Lingyu , Zhang Hao , Huang Hongtao , Wang Jingyi , Zhou Hongyu , Yu Tongpu
Published: January 2024

With the development of ultra-intense laser technology, the manipulation of relativistic laser pulses has become progressively challenging due to the limitations of damage thresholds for traditional optical devices. In recent years, the generation and manipulation of ultra-intense vortex laser pulses by plasma has attracted a great deal of attention. Here, we propose a new scheme to produce a relativistic vortex laser. This is achieved by using a relativistic Gaussian drive laser to irradiate a plasma binary phase square spiral zone plate (BPSSZP). Based on three-dimensional particle-in-cell (3D-PIC) simulations, we find that the drive laser has a phase difference of π after passing through the BPSSZP, ultimately generating the vortex laser with unique square symmetry. Quantitatively, by employing a drive laser pulse with intensity of 1.3 × 1018~W/cm2, a vortex laser with intensity up to 1.8 × 1019~W/cm2, and energy conversion efficiency of 18.61% can be obtained. The vortex lasers generated using the BPSSZP follow the modulo-4 transmutation rule when varying the topological charge of BPSSZP. Furthermore, the plasma-based BPSSZP has exhibited robustness and the ability to withstand multiple ultra-intense laser pulses. As the vortex laser generated via the BPSSZP has high intensity and large energy conversion efficiency, our scheme may hold potential applications in the community of laser-plasma, such as particles acceleration, intense high-order vortex harmonic generation, and vortex X/γ-ray sources.
Orthogonality of non-coaxial Laguerre-Gaussian beams
Authors: Liu Yi-Dong , Yang Xuebo , Wang Jiandong , Wang Ran , Yang Yuanjie
Published: January 2024

The conventional orthogonality of Laguerre-Gaussian (LG) beams is widely recognized and serves as the fundamental basis for mode division multiplexing utilizing LG beams as channels. However, this conventional orthogonality holds true only when two LG beams share the same axis. Whether non-coaxial LG beams, with parallel axes separated by a distance, are orthogonal to each other remains an open question. To address this issue and reveal the orthogonality of non-coaxial LG beams, we analytically derive the projection of one LG beam onto another. This projection exhibits a helical phase and a rotationally symmetric amplitude with dark rings present. These dark rings indicate that two non-coaxial LG beams are indeed orthogonal to each other when their axes are appropriately separated. Furthermore, any pair of non-coaxial LG beams within a set also exhibit orthogonality when their axes are fixed at a certain separation distance. This novel form of orthogonality predicts an innovative compound multiplexing technique that simultaneously combines mode and space, enabling more efficient packing of multiple LG beams within a single transmission aperture while maintaining parallel and closely spaced beam axes.
Design and demonstration of high-power density infrared nonlinear filtering window with EM shielding
Authors: Kui Wen , Xianjun Huang , Tao Tian , Wentao Huang , Peiguo Liu
Published: January 2024

Directional energy weapons such as high-power microwaves and high-energy lasers pose a huge threat to optoelectronic detection systems. With that in mind, we designed an infrared optical window that has a nonlinear optical response to high-energy lasers and electromagnetic shielding to microwaves. By constructing a periodic metal circular hole array structure at the subwavelength scale, surface plasmons resonance is excited and its local field enhanced characteristics are utilized to form information transmission compatibility in the infrared band. At the same time, after laser etching off the subwavelength structure, the remaining metal forms a continuous conductive structure, forming an ultra-wideband shielding layer to achieve ultra-high and wide protection in the microwave band. Moreover, a layer of Ge2Sb2Te5 thin film was deposited between the transparent substrate and the metal film. Utilizing its nonlinear optical properties of high-temperature phase transition to reduce damage of directed energy weapons to the photoelectric detection system and equipment. Thus, when the photoelectric detection system or device is damaged or interfered by signals of different frequency bands or energies, the filtering window can achieve multi-mode shielding function.
Expanding gain bandwidth using ion-hybridized fiber for kHz-linewidth single-frequency fiber lasers at S-, C-, and L-bands: design and performance evaluation
Authors: Ji Yao , Zhu Jinzhong , Li Jialong , Yang Changsheng , Wang Weichao
Published: January 2024

Single-frequency fiber lasers at S-, C-, and L-bands play a crucial role in various applications such as optical network expansion, high-precision metrology, coherent lidar, and atomic physics. However, compared to the C-band, the S- and L-bands have wavelength deviations and suffer from excited-state absorption, which limits the output performance. To address this issue, a strategy called ion hybridization has been proposed to increase the differences in site locations of rare earth (RE) ions in the laser matrix, thereby achieving a broader gain bandwidth. This strategy has been applied to an Er3+/Yb3+ co-doped modified phosphate fiber (EYMPF), resulting in gain coefficients per unit length greater than 2 dB/cm at S-, C-, and L-bands. To demonstrate its capabilities, several centimeter-long EYMPFs have been used to generate single-frequency laser outputs at S-, C- and L-bands with kHz-linewidths, high signal-to-noise ratios (>70 dB), and low relative intensity noise (<–130 dB/Hz) in a compact short linear-cavity configuration.
Phase to intensity modulation and fading compensation using a single ring resonator for radio-over-fiber links
Authors: Lai Zhi , Zhang Zhenjiang , Shi Teng , Guo Liang
Published: January 2024

In this study, we present a simulation-based analysis of radio-over-fiber (ROF) transmission links incorporating both phase modulation (PM) and a single ring resonator (RR) as the modulation transformer (MT). This configuration offers cost-effectiveness, enhanced operational stability, facile reconfiguration, and heightened robustness. The optimization of the RR involves a comprehensive adjustment of the power coupler coupling coefficient (k) and the roundtrip optical phase shift (φ) to attain superior characteristics in terms of power output, bandwidth, dispersion, and nonlinearity, individually. The simulation encompasses the transmission of diverse data formats, including QPSK, 16QAM, and 16QAM-based OFDM, modulated by the PM-RR system. The results reveal a 0.25 dB improvement in nonlinearity tolerance, increased power, and superior fading mitigation compared to the conventional intensity modulation (IM) approach. Furthermore, through careful tuning of the phase response, the Q factor of the PM-RR system exhibits an enhancement exceeding 40% over a 100 km fiber length when compared to the Mach-Zehnder modulator (MZM) system.
Coherent optical transmitter IQ imbalance mitigation with embedded carrier phase and frequency offset estimation
Authors: Gong Zepeng , Shi Fan , Hu Xuemeng , Luo Ming , Zhang Xu , Huang Tianye , Li Xiang
Published: January 2024

We present a 4×4 real-valued channel equalizer with embedded phase estimator, designed for carrier phase and frequency offset estimation and compensation in coherent optical communications with in-phase/quadrature (IQ) impairments. These impairments include IQ timing skew, gain imbalance, and quadrature phase errors at the transmitter side. To achieve adaptive control of the equalizer’s filter coefficients, we employ the decision-directed least mean square (DD-LMS) algorithm. This algorithm minimizes the error between the filter outputs and the desired signals in a symbol-by-symbol manner, resulting in faster channel coefficients adaptation speed. Simulation results for a 60 GBaud polarization-multiplexing 16 quadrature amplitude modulation (PM-16QAM) signal demonstrate that our proposed equalizer outperforms a 2×2 cascaded multi modulus algorithm-based (CMMA-based) equalizer, a 2×2 complex-valued method based on the DD-LMS algorithm, and the 4×4 real-valued equalizer without embedded frequency offset estimation (FOE), when the transmitter IQ impairments exist. Experimental validation is also conducted for the 60 GBaud PM-16QAM and 45 GBaud PM-64QAM signals. Similar to the simulation results, our experiments show that the proposed 4×4 real-valued equalizer with embedded FOE can achieve effective SNR penalties of less than 0.41 dB at 7 ps skew, 1.33 dB at 3.5 dB gain imbalance, and 1.64 dB at the bias voltage shift of 0.5 V for the 60 GBaud PM-16QAM signal. Finally, our experimental results confirm the effectiveness of our proposed method in carrier phase estimation as well as the frequency offset compensation, when compared with 4×4 real-valued equalizer without embedded FOE.
Pressure sensing with two-color laser absorption spectroscopy for combustion diagnostics
Authors: Wang Ruifeng , Huang Tianxu , Mei Jiaoxu , Wang Guishi , Liu Kun , Kan Ruifeng , Chen Weidong , Gao Xiaoming
Published: January 2024

Pressure is an important parameter in assessing combustion performance that is typically measured using contact sensors. However, contact sensors usually disturb combustion flows and suffer from the temperature tolerance limit of sensor materials. In this Letter, an innovative noncontact two-color pressure sensing method based on tunable diode laser absorption spectroscopy (TDLAS) is proposed. This makes it possible to measure pressure at high temperature environments for combustion diagnostics. The proposed method uses the linear combination of the collision-broadened linewidths of two H2O absorption lines near 1343 and 1392 nm to measure the pressure. The feasibility and performance of such method have been demonstrated by measuring pressures from 1 to 5 bars at temperatures up to 1300 K with a laser wavelength scanning rate of 20 kHz. Measurement errors were found to be within 3%. Compared to previously reported TDLAS pressure sensors, this method is free from the influence of concentration and can also be combined with the existing two-color TDLAS thermometry to realize a fast, on line, and multi-parameter measurement in combustion diagnostics.
High-order optical vortex beam generation based on watt-class spatial phase plate-integrated photonic-crystal surface-emitting lasers
Authors: Tokushima Tomoki , Noda Susumu , Kitamura Kyoko
Published: January 2024

We develop spatial phase plate (SPP)-integrated photonic-crystal surface-emitting lasers featuring double-lattice photonic-crystal structures embedded using a crystal regrowth technique. SPPs possessing eight segmentations per phase rotation number l are fabricated on the top surface to generate optical vortex beams (OVBs) with l = 1–3. The beams exhibit a high output power of ∼5 W and high mode purities of 85%, 78%, and 72% for l = 1–3, respectively. These purity values are comparable with those of a pure Gaussian mode passing through an SPP. The compact, high-power, and high-purity OVB sources can be used in the fields of material processing, optical manipulation, and microscopy.
Integrated liquid-crystal-based variable-tap devices for visible-light amplitude modulation
Authors: Notaros Milica , Coleto Andres Garcia , Raval Manan , Notaros Jelena
Published: January 2024

In this Letter, we propose and experimentally demonstrate the first, to our knowledge, integrated liquid-crystal-based (LC-based) variable-tap devices for visible-light amplitude modulation. These devices leverage the birefringence of LC medium to actively tune the coupling coefficient between two waveguides. First, we develop the device structure, theory of operation, and design procedure. Next, we summarize the fabrication and LC packaging procedure for these devices. Finally, we experimentally demonstrate amplitude modulation with 15.4-dB tap-port extinction within ±3.1 V for a 14-µm-long device at a 637-nm operating wavelength. These small-form-factor variable-tap devices provide a compact and low-power solution to integrated visible-light amplitude modulation and will enable future high-density integrated visible-light systems.
Modelocking of a frequency-shifted feedback laser triggered by amplitude modulation
Authors: Cuenca Miguel , Maestre Haroldo , Fernández-Pousa Carlos R.
Published: January 2024

We report an experimental technique to trigger modelocking (ML) emission in frequency-shifted feedback (FSF) lasers. These lasers feature an intracavity modulator driven by a radio frequency tone, which shifts the light spectrum every cavity round trip. The technique consists of the drive of the modulator with a second tone at the cavity free spectral range (FSR) frequency. So, in addition to the frequency shift, a weak amplitude modulation (AM) appears synchronous with the cavity round trip time. The approach is successful as FSF cavities support chirped modes evenly spaced by the FSR, whose AM coupling produces convenient seed pulses for the ML onset. This results in ML emission at arbitrary frequency shifts and initiation thresholds lower than in standard, spontaneous FSF laser ML. Simulations indicate that the role of AM is to trigger the formation of ML pulses, but the primary mechanism of pulse buildup is the Kerr effect. The technique opens a new, to the best of our knowledge, practical route to initiate ML emission in FSF lasers.