Publications by authors named "Mengdong He"

In this paper, we have investigated optical bistability modulation of transmitted beam that can be achieved by graphene sandwich structure with topological interface modes at terahertz frequency. Graphene with strong nonlinear optical effect was combined with sandwich photonic crystal to form a new sandwich structure with topological interface modes. The light-limiting properties of the topological interface modes, as well as its high unidirectionality and high transmission efficiency, all contribute positively to the reduction of the optical bistability threshold.

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We theoretically explore the conditions for generating optical bistability (OB) in a heterodimer comprised of a semiconductor quantum dot (SQD) and a metallic nanoshell (MNS). The MNS is made of a metallic nanosphere as a core and a dielectric material as a shell. For the specific hybrid system considered, the bistable effect appears only if the frequency of the pump field is equal to (or slightly less than) the exciton frequency for a proper shell thickness.

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Optical differential operation based on the photonic spin Hall effect(SHE) has attracted extensive attention in image processing of edge detection, which has advantages of high speed, parallelism, and low power consumption. Here, we theoretically demonstrate tunable optical differential operation in a four-layered nanostructure of prism-graphene-air gap-substrate. It is shown that the spatial differentiation arises inherently from the photonic SHE.

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Background: Hydroxychloroquine is often used as a first-line treatment of rheumatoid arthritis despite limited evidence on its cardiovascular risk.

Objectives: We conducted a cardiovascular safety evaluation comparing hydroxychloroquine to methotrexate among patients with rheumatoid arthritis.

Methods: Using Medicare data (2008-2016), we identified 54,462 propensity score-matched patients with rheumatoid arthritis, aged ≥65 years, who initiated hydroxychloroquine or methotrexate.

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Objectives: To characterise the incidence rate of skin cancer associated with methotrexate and hydroxychloroquine in older adults with rheumatoid arthritis (RA).

Methods: RA patients aged ≥65 years who initiated methotrexate or hydroxychloroquine as their first disease modifying antirheumatic drugs (DMARDs). The primary outcome was new occurrence of any skin cancer (i.

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We propose a scheme to generate ultra-strong four-wave mixing (FWM) signal based on a suspended monolayer graphene nanoribbon nanomechanical resonator (NR) coupled to an Au nanoparticle (NP). It is shown that, the FWM spectrum can switch among two-peaked, three-peaked, four-peaked or five-peaked via the modulation of exciton-phonon and exciton-plasmon couplings. This is mainly attributed to the vibrational properties of NR related to the exciton-phonon coupling, and the energy-level splitting of the localized exciton correlated to three classes of resonances consisting of three-photon resonance, Rayleigh Resonance, and AC-Stark atomic resonance.

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Aims: Patients with rheumatoid arthritis (RA) have an increased risk of venous thromboembolism (VTE), likely related to underlying inflammation. We examined VTE risk associated with two commonly used immunomodulators in RA patients, methotrexate and hydroxychloroquine.

Methods And Results: Using U.

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Objective: Medications frequently require prior authorization from payers before filling is authorized. Obtaining prior authorization can create delays in filling prescriptions and ultimately reduce patient adherence to medication. Electronic prior authorization (ePA), embedded in the electronic health record (EHR), could remove some barriers but has not been rigorously evaluated.

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Many real-word evidence (RWE) studies that utilize existing healthcare data to evaluate treatment effects incur substantial but avoidable bias from methodologically flawed study design; however, the extent of preventable methodological pitfalls in current RWE is unknown. To characterize the prevalence of avoidable methodological pitfalls with potential for bias in published claims-based studies of medication safety or effectiveness, we conducted an English-language search of PubMed for articles published from January 1, 2010 to May 20, 2019 and randomly selected 75 studies (10 case-control and 65 cohort studies) that evaluated safety or effectiveness of cardiovascular, diabetes, or osteoporosis medications using US health insurance claims. General and methodological study characteristics were extracted independently by two reviewers, and potential for bias was assessed across nine bias domains.

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Article Synopsis
  • The study aimed to compare the risk of nonvertebral osteoporotic fractures (NVFs) in rheumatoid arthritis (RA) patients starting treatment with biologic or targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs).
  • Data from multiple sources, including Optum, Medicare, and MarketScan, involving over 134,000 patients were analyzed, using adalimumab as a reference treatment.
  • Results showed that the risk of composite NVFs was similar for all b/tsDMARDs compared to adalimumab, indicating no significant differences in fracture risk across the various treatments studied.
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Purpose: Accurately identifying patients with psoriasis (PsO) is crucial for generating real-world evidence on PsO disease course and treatment utilization.

Methods: We developed nine claims-based algorithms for PsO using a combination of the International Classification of Diseases (ICD)-9 codes, specialist visit, and medication dispensing using Medicare linked to electronic health records data (2013-2014) in two healthcare provider networks in Boston, Massachusetts. We calculated positive predictive value (PPV) and 95% confidence interval (CI) for each algorithm using the treating physician's diagnosis of PsO via chart review as the gold standard.

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Article Synopsis
  • REMS programs aim to improve the safe use of FDA-approved drugs, but there is ongoing debate about their effectiveness.
  • This study focused on analyzing changes in the prescription of erythropoiesis stimulating agents (ESAs), specifically darbepoetin alfa and epoetin alfa, among cancer patients after a REMS warning against their use in patients with hemoglobin levels above 10 g/dL.
  • The results showed a decline in the initiation rates of both drugs among cancer patients, yet the changes observed post-implementation and enforcement of the REMS program were not statistically significant.
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Importance: Congenital cytomegalovirus (cCMV) has received far less clinical and public health attention as a teratogenic infection than the Zika virus epidemic. However, cCMV may be responsible for a large fraction of microcephaly cases in the United States.

Objective: To evaluate the association between cCMV and the prevalence at birth of microcephaly in the United States.

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This study examines the most commonly dispensed categories and individual substances of all prescribed controlled substances, including stimulants, benzodiazepines, and depressants, among US commercially insured adults.

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Background: The Medicaid Analytic eXtract (MAX) is a health care utilization database from publicly insured individuals that has been used for studies of drug safety in pregnancy. Claims-based algorithms for defining many important maternal and neonatal outcomes have not been validated.

Objective: To validate claims-based algorithms for identifying selected pregnancy outcomes in MAX using hospital medical records.

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We theoretically propose a dual-channel bistable switch based on a monolayer Z-shaped graphene nanoribbon nanoresonator (NR) coupled to a metal nanoparticle (MNP). We show that the bistable nonlinear absorption response can be realized due to a competition and combination of the exciton-plasmon and exciton-phonon interactions. We map out two-dimensional and three-dimensional bistability phase diagrams, which reveal clearly the dynamical evolution of the roles played by these two interactions in managing optical bistability (OB) at all stages.

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Purpose: The Centers for Medicare and Medicaid Services (CMS) mandated the transition from ICD-9 to ICD-10 codes on October 1, 2015. Postmarketing surveillance of newly marketed drugs, including novel biologics and biosimilars, requires a robust approach to convert ICD-9 to ICD-10 codes for study variables. We examined three mapping methods for health conditions (HCs) of interest to the Biologics and Biosimilars Collective Intelligence Consortium (BBCIC) and compared their prevalence.

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Aim: To review the methodology of observational studies examining the association between glucose-lowering medications and cancer to identify the most common methodological challenges and sources of bias.

Methods: We searched PubMed systematically to identify observational studies on glucose-lowering medications and cancer published between January 2000 and January 2016. We assessed the design and analytical methods used in each study, with a focus on their ability to achieve study validity, and further evaluated the prevalence of major methodological choices over time.

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This study uses data from the Optum Clinformatics Data Mart to evaluate trends in outpatient prescription of opioids to persons 18 years or younger in the United States from 2004 to 2017.

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For thirty-five years the Orphan Drug Act of 1983 has provided incentives for pharmaceutical manufacturers to develop drugs to treat rare diseases-conditions that affect fewer than 200,000 people in the US. One key statutory incentive is an exclusive seven-year marketing right for the rare disease indication, which has been heralded as driving a dramatic increase in the number of rare disease treatments. However, most new drugs are also protected by patents.

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We present a study for the impact of exciton-phonon and exciton-plasmon interactions on bistable four-wave mixing (FWM) signals in a metal nanoparticle (MNP)-monolayer MoS nanoresonator hybrid system. Via tracing the FWM response we predict that, depending on the excitation conditions and the system parameters, such a system exhibits 'U-shaped' bistable FWM signals. We also map out bistability phase diagrams within the system's parameter space.

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Postapproval drug safety studies often use propensity scores (PSs) to adjust for a large number of baseline confounders. These studies may involve examining whether treatment safety varies across subgroups. There are many ways a PS could be used to adjust for confounding in subgroup analyses.

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We perform a theoretical study of the bistable four-wave mixing (FWM) response in a coupled system comprised of a semiconductor quantum dot (SQD) and a photonic crystal (PC) nanocavity in which the SQD is embedded. It is shown that the shape of the FWM spectrum can switch among single-peaked, double-peaked, triple-peaked, and four-peaked arising from the vacuum Rabi splitting and the exciton-nanocavity coupling. Especially, we map out bistability phase diagrams within a parameter subspace of the system, and find that it is easy to turn on or off the bistable FWM response by only adjusting the excitation frequency or the pumping intensity.

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Purpose: When evaluating safety signals, there is often interest in understanding safety in all patients for whom compared treatments are reasonable alternatives, as well as in specific subgroups of interest. There are numerous ways that propensity score (PS) matching can be implemented for subgroup analyses.

Methods: We conducted a systematic literature review of methods papers that compared the performance of alternative methods to implement PS matched subgroup analyses and examined how frequently different PS matching methods have been used for subgroup analyses in applied studies.

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