Incident dementia and long-term exposure to constituents of fine particle air pollution: A national cohort study in the United States.

Growing evidence suggests that fine particulate matter (PM2.5) likely increases the risks of dementia, yet little is known about the relative contributions of different constituents. Here, we conducted a nationwide population-based cohort study (2000 to 2017) by integrating the Medicare Chronic Conditions Warehouse database and two independently sourced datasets of high-resolution PM2.5 major chemical composition, including black carbon (BC), organic matter (OM), nitrate (NO3-), sulfate (SO42-), ammonium (NH4+), and soil dust (DUST). To investigate the impact of long-term exposure to PM2.5 constituents on incident all-cause dementia and Alzheimer's disease (AD), hazard ratios for dementia and AD were estimated using Cox proportional hazards models, and penalized splines were used to evaluate potential nonlinear concentration-response (C-R) relationships. Results using two exposure datasets consistently indicated higher rates of incident dementia and AD for an increased exposure to PM2.5 and its major constituents. An interquartile range increase in PM2.5 mass was associated with a 6 to 7% increase in dementia incidence and a 9% increase in AD incidence. For different PM2.5 constituents, associations remained significant for BC, OM, SO42-, and NH4+ for both end points (even after adjustments of other constituents), among which BC and SO42- showed the strongest associations. All constituents had largely linear C-R relationships in the low exposure range, but most tailed off at higher exposure concentrations. Our findings suggest that long-term exposure to PM2.5 is significantly associated with higher rates of incident dementia and AD and that SO42-, BC, and OM related to traffic and fossil fuel combustion might drive the observed associations.

Thin-film lithium niobate electro-optic isolator fabricated by photolithography assisted chemo-mechanical etching.

We report an electro-optic isolator fabricated on thin-film lithium niobate by photolithography-assisted chemo-mechanical etching that shows an isolation of 39.50 dB and an overall fiber-to-fiber loss of 2.6 dB.

Erbium-ytterbium codoped thin-film lithium niobate integrated waveguide amplifier with a 27†dB internal net gain.

A photonic integrated waveguide amplifier fabricated on erbium-ytterbium (Er-Yb) codoped thin-film lithium niobate (TFLN) has been investigated in this work. A small-signal internal net gain of 27 dB is achieved at a signal wavelength of 1532 nm in the fabricated Er-Yb TFLN waveguide amplifier pumped by a diode laser at ≈980 nm. Experimental characterizations reveal the suitability of waveguide fabrication by the photolithography-assisted chemo-mechanical etching (PLACE) technique and also the gain in an Yb-sensitized-Er material. The demonstrated high-gain chip-scale TFLN amplifier is promising for interfacing with established lithium niobate integrated devices, greatly extending the spectrum of TFLN photonic applications.

On-chip single-mode thin-film lithium niobate Fabry-Perot resonator laser based on Sagnac loop reflectors.

We demonstrate an on-chip single-mode Er3+-doped thin-film lithium niobate (Er:TFLN) laser which consists of a Fabry-Perot (FP) resonator based on Sagnac loop reflectors (SLRs). The fabricated Er:TFLN laser has a footprint of 6.5 mm × 1.5 mm with a loaded quality (Q) factor of 1.6 × 105 and a free spectral range (FSR) of 63 pm. We generate the single-mode laser at 1544 nm wavelength with a maximum output power of 44.7 µW and a slope efficiency of 0.18%.

On-chip coherent beam combination of waveguide amplifiers on Er3+-doped thin film lithium niobate.

We demonstrate on-chip coherent beam combination of two waveguide amplifiers on Er3+-doped thin film lithium niobate (Er:TFLN) platform. Our device is built based on an electro-optic modulator fabricated on Er:TFLN. The output power of the coherently combined amplifiers is measured as high as 12.9 mW, surpassing that of previous single waveguide amplifiers based on an Er3+-doped thin film lithium niobate platform.

Experiences of Stigma and HIV Status Associated with Awareness and Usage of Safer Sex Functions in Dating Apps Among MSM, 2019 American Men's Internet Survey (AMIS) Study.

Dating apps represent opportunities to implement sexual health interventions among gay, bisexual, and other men who have sex with men (MSM), particularly those who may avoid traditional health services due to intersecting stigmas. We used multivariable models to explore whether stigma experience was associated with awareness and usage of safer sex functions in dating apps among 7700 MSM who completed a 2019 US nationwide online survey. Perceived community intolerance of gay and bisexual men was associated with reduced awareness of sexual health strategy profile options (adjusted prevalence ratio [aPR] 0.95; 95% confidence interval [95% CI] 0.93-0.98) and sexual health information and resources (aPR 0.97; 95% CI 0.94-0.99). Stigma from family and friends was associated with increased usage of app-based sexual health reminders (aPR 1.14; 95% CI 1.02-1.28) and sexual health information and resources (aPR 1.16; 95% CI 1.04-1.31). Stigma experience of MSM should be considered in optimizing app-based sexual health interventions.

National Cohort Study of Long-Term Exposure to PM2.5 Components and Mortality in Medicare American Older Adults.

There is increasing evidence linking long-term fine particulate matter (PM2.5) exposure to negative health effects. However, the relative influence of each component of PM2.5 on health risk is poorly understood. In a cohort study in the contiguous United States between 2000 and 2017, we examined the effect of long-term exposure to PM2.5 main components and all-cause mortality in older adults who had to be at least 65 years old and enrolled in Medicare. We estimated the yearly mean concentrations of six key PM2.5 compounds, including black carbon (BC), organic matter (OM), soil dust (DUST), nitrate (NO3-), sulfate (SO42-), and ammonium (NH4+), using two independently sourced well-validated prediction models. We applied Cox proportional hazard models to evaluate the hazard ratios for mortality and penalized splines for assessing potential nonlinear concentration-response associations. Results suggested that increased exposure to PM2.5 mass and its six main constituents were significantly linked to elevated all-cause mortality. All components showed linear concentration-response relationships in the low exposure concentration ranges. Our research indicates that long-term exposure to PM2.5 mass and its essential compounds are strongly connected to increased mortality risk. Reductions of fossil fuel burning may yield significant air quality and public health benefit.

A Fine-Grained Semantic Alignment Method Specific to Aggregate Multi-Scale Information for Cross-Modal Remote Sensing Image Retrieval.

Due to the swift growth in the scale of remote sensing imagery, scholars have progressively directed their attention towards achieving efficient and adaptable cross-modal retrieval for remote sensing images. They have also steadily tackled the distinctive challenge posed by the multi-scale attributes of these images. However, existing studies primarily concentrate on the characterization of these features, neglecting the comprehensive investigation of the complex relationship between multi-scale targets and the semantic alignment of these targets with text. To address this issue, this study introduces a fine-grained semantic alignment method that adequately aggregates multi-scale information (referred to as FAAMI). The proposed approach comprises multiple stages. Initially, we employ a computing-friendly cross-layer feature connection method to construct a multi-scale feature representation of an image. Subsequently, we devise an efficient feature consistency enhancement module to rectify the incongruous semantic discrimination observed in cross-layer features. Finally, a shallow cross-attention network is employed to capture the fine-grained semantic relationship between multiple-scale image regions and the corresponding words in the text. Extensive experiments were conducted using two datasets: RSICD and RSITMD. The results demonstrate that the performance of FAAMI surpasses that of recently proposed advanced models in the same domain, with significant improvements observed in R@K and other evaluation metrics. Specifically, the mR values achieved by FAAMI are 23.18% and 35.99% for the two datasets, respectively.

Simultaneous spatial and temporal focusing optical vortex pulses for micromachining through optically transparent materials.

We introduce the optical vortex beam into simultaneous spatial and temporal focusing (SSTF) technique, and theoretically and experimentally demonstrate the local control of peak intensity distribution at the focus of a simultaneous spatiotemporally focused optical vortex (SSTF OV) beam. To avoid nonlinear self-focusing in the conventional focusing scheme, a spatiotemporally focused femtosecond laser vortex beam was employed to achieve doughnut-shaped ablation and high aspect ratio (∼28) microchannels on the back surface of 3 mm thick soda-lime glass and fused silica substrates.

Laser diode-pumped compact hybrid lithium niobate microring laser.

We demonstrate a compact hybrid lithium niobate microring laser by butt coupling a commercial 980-nm pump laser diode chip with a high-quality Er3+-doped lithium niobate microring chip. Single-mode lasing emission at 1531-nm wavelength from the Er3+-doped lithium niobate microring can be observed with the integrated 980-nm laser pumping. The compact hybrid lithium niobate microring laser occupies the chip size of 3 mm × 4 mm × 0.5 mm. The threshold pumping laser power is 6 mW and the threshold current is 0.5 A (operating voltage 1.64 V) at atmospheric temperature. The spectrum featuring single-mode lasing with small linewidth of 0.05 nm is observed. This work explores a robust hybrid lithium niobate microring laser source which has potential applications in coherent optical communication and precision metrology.

On-chip microdisk laser on Yb3+-doped thin-film lithium niobate.

We demonstrate an on-chip Yb3+-doped lithium niobate (LN) microdisk laser. The intrinsic quality factors of the fabricated Yb3+-doped LN microdisk resonator are measured up to 3.79×105 at a 976 nm wavelength and 1.1×106 at a 1514 nm wavelength. The multi-mode laser emissions are obtained in a band from 1020 to 1070 nm pumped by a 984 nm laser and with the low threshold of 103µW, resulting in a slope efficiency of 0.53% at room temperature. Furthermore, both the second-harmonic frequency of pump light and the sum frequency of the pump light and laser emissions are generated in the on-chip Yb3+-doped LN microdisk, benefiting from the strong χ(2) nonlinearity of LN. These microdisk lasers are expected to contribute to the high-density integration of a lithium niobate on insulator-based photonic chip.

Electro-optically tunable microring laser monolithically integrated on lithium niobate on insulator.

We demonstrate monolithic integration of an electro-optically (EO) tunable microring laser on lithium niobate on insulator (LNOI) platform. The device is fabricated by photolithography assisted chemo-mechanical etching, and the pump laser is evanescently coupled into the erbium (${\rm{E}}{{\rm{r}}^{3 +}}$)-doped lithium niobate (LN) microring laser using an undoped LN waveguide mounted above the microring. The quality factor of the LN microring resonator is measured as high as ${1.54} \times {{1}}{{{0}}^5}$ at the wavelength of 1542 nm. Lasing action can be observed at a pump power threshold below 3.5 mW using a 980 nm continuous-wave pump laser. Finally, tuning of the laser wavelength is achieved by varying the electric voltage on the microelectrodes fabricated in the vicinity of a microring waveguide, showing an EO coefficient of 0.33 pm/V.

Gain dynamics of a free-space nitrogen laser pumped by circularly polarized femtosecond laser pulses.

We experimentally demonstrate ultrafast dynamic of generation of the 337-nm nitrogen laser by injecting an external seed pulse into a femtosecond laser filament pumped by a circularly polarized laser pulse. In the pump-probe scheme, it is revealed that the population inversion between the C(3)Π(u) and B(3)Π(g) states of N(2) for the free-space 337-nm laser is firstly built up on the timescale of several picoseconds, followed by a relatively slow decay on the timescale of tens of picoseconds, depending on the nitrogen gas pressure. By measuring the intensities of 337-nm signal from nitrogen gas mixed with different concentrations of oxygen gas, it is also found that oxygen molecules have a significant quenching effect on the nitrogen laser signal. Our experimental observations agree with the picture of electron-impact excitation.

Generation of an air laser at extended distances by femtosecond laser filamentation with telescope optics.

We present the generation of self-induced-white-light-seeded lasing action of nitrogen molecules in air by a Ti:sapphire femtosecond laser (800 nm, 5.5 mJ) and demonstrate that such lasing action is strongly influenced by external focusing conditions. It is found that the self-seeded lasing signal of N(2)(+) at ~391 nm decreases dramatically by orders of magnitude and ultimately disappears when the focal length of an external lens increases from 0.5 m to 1 m. By using a telescope, it is shown that such limitation can be overcome and the 391 nm lasing can be controlled to occur at remotely designated distance, providing a possibility for practical applications in standoff spectroscopy.

Second harmonic generation in centrosymmetric gas with spatiotemporally focused intense femtosecond laser pulses.

We demonstrate unexpectedly strong second harmonic generation (SHG) in argon gas by use of spatio-temporally focused (SF) femtosecond laser pulses. The resulting SHG by the SF scheme at a 75 cm distance shows a significantly enhanced efficiency than that achieved with conventional focusing schemes, which offers a new promising possibility for standoff applications. Our theoretical calculations reasonably reproduce the experimental observations, which indicate that the observed SHG mainly originates from the gradient of non-uniform plasma dynamically controlled by the SF laser field.

Impulsive rotational Raman scattering of N2 by a remote "air laser" in femtosecond laser filament.

We report on experimental realization of impulsive rotational Raman scattering from neutral nitrogen molecules in a femtosecond laser filament using an intense self-induced white-light seeding "air laser" generated during the filamentation of an 800 nm Ti:sapphire laser in nitrogen gas. The impulsive rotational Raman fingerprint signals are observed with a maximum conversion efficiency of ∼0.8%. Our observation provides a promising way of remote identification and location of chemical species in the atmosphere by a rotational Raman scattering of molecules.

Identification of the physical mechanism of generation of coherent N2(+) emissions in air by femtosecond laser excitation.

Recently, amplification of harmonic-seeded radiation generated through femtosecond laser filamentation in air has been observed, giving rise to coherent emissions at wavelengths corresponding to transitions between different vibrational levels of the electronic B(2)Σ(u)(+) and X(2)Σ(g)(+) states of molecular nitrogen ions [Phys. Rev. A. 84, 051802(R) (2011)]. Here, we carry out systematic investigations on its physical mechanism. Our experimental results do not support the speculation that such excellent coherent emissions could originate from nonlinear optical processes such as four-wave mixing or stimulated Raman scattering, leaving stimulated amplification of harmonic seed due to the population inversion generated in molecular nitrogen ions the most likely mechanism.

Alignment-dependent fluorescence emission induced by tunnel ionization of carbon dioxide from lower-lying orbitals.

The study of the ionization process of molecules in an intense infrared laser field is of paramount interest in strong-field physics and constitutes the foundation of imaging of molecular valence orbitals and attosecond science. We show measurement of alignment-dependent ionization probabilities of the lower-lying orbitals of the molecules by experimentally detecting the alignment dependence of fluorescence emission from tunnel ionized carbon dioxide molecules. The experimental measurements are compared with the theoretical calculations of the strong field approximation and molecular Ammosov-Delone-Krainov models. Our results demonstrate the feasibility of an all-optical approach for probing the ionization dynamics of lower-lying orbitals of molecules, which is until now still difficult to achieve by other techniques. Moreover, the deviation between the experimental and theoretical results indicates the incompleteness of current theoretical models for describing strong field ionization of molecules.

Short-term associations between ambient air pollution and emergency department visits for Alzheimer's disease and related dementias.

Dementia is a seriously disabling illness with substantial economic and social burdens. Alzheimer's disease and its related dementias (AD/ADRD) constitute about two-thirds of dementias. AD/ADRD patients have a high prevalence of comorbid conditions that are known to be exacerbated by exposure to ambient air pollution. Existing studies mostly focused on the long-term association between air pollution and AD/ADRD morbidity, while very few have investigated short-term associations. This study aims to estimate short-term associations between AD/ADRD emergency department (ED) visits and three common air pollutants: fine particulate matter (PM2.5), nitrogen dioxide (NO2), and warm-season ozone. Methods: For the period 2005 to 2015, we analyzed over 7.5 million AD/ADRD ED visits in five US states (California, Missouri, North Carolina, New Jersey, and New York) using a time-stratified case-crossover design with conditional logistic regression. Daily estimated PM2.5, NO2, and warm-season ozone concentrations at 1 km spatial resolution were aggregated to the ZIP code level as exposure. Results: The most consistent positive association was found for NO2. Across five states, a 17.1 ppb increase in NO2 concentration over a 4-day period was associated with a 0.61% (95% confidence interval = 0.27%, 0.95%) increase in AD/ADRD ED visits. For PM2.5, a positive association with AD/ADRD ED visits was found only in New York (0.64%, 95% confidence interval = 0.26%, 1.01% per 6.3 µg/m3). Associations with warm-season ozone levels were null. Conclusions: Our results suggest AD/ADRD patients are vulnerable to short-term health effects of ambient air pollution and strategies to lower exposure may reduce morbidity.

Wavelength-Tunable Narrow-Linewidth Laser Diode Based on Self-Injection Locking with a High-Q Lithium Niobate Microring Resonator.

We demonstrate a narrow linewidth 980 nm laser by self-injection locking of an electrically pumped distributed-feedback (DFB) laser diode to a high quality (Q) factor (>105) lithium niobate (LN) microring resonator. The lithium niobate microring resonator is fabricated by photolithography-assisted chemo-mechanical etching (PLACE) technique, and the Q factor of lithium niobate microring is measured as high as 6.91 × 105. The linewidth of the multimode 980 nm laser diode, which is ~2 nm measured from its output end, is narrowed down to 35 pm with a single-mode characteristic after coupling with the high-Q LN microring resonator. The output power of the narrow-linewidth microlaser is about 4.27 mW, and the wavelength tuning range reaches 2.57 nm. This work explores a hybrid integrated narrow linewidth 980 nm laser that has potential applications in high-efficient pump laser, optical tweezers, quantum information, as well as chip-based precision spectroscopy and metrology.