Ultrashort pulse propagation in fibers is affected by intrapulse Raman scattering (IRS) which causes both a linear frequency downshift and a quadratic displacement of the peak pulse, as functions of the propagation distance. This effect has been known and treated by perturbation methods applied to the nonlinear Schrödinger equation since the period of intense research on soliton propagation. Here, we find solutions of the model equation using an accelerating self-similarity variable and study their stability. These solutions have Airy function asymptotics which give them infinite energy. For small IRS, the algebraically decaying tail is negligible and these solutions are a very good approximation of the profiles observed in the full equation simulations. For strong IRS (but beyond the regime in which the evolution equation is valid for silica fibers), the self-similar pulses have noticeable left tails exhibiting Airy oscillations. Whenever their truncated forms are used as initial conditions of the full equation, they experience amplitude decay and show left tails that are consistent with radiation escaping from the central pulse. These observations are interpreted as being the effects of a continuum constitution of the infinite left tail.
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http://dx.doi.org/10.1103/PhysRevE.81.046604 | DOI Listing |
AIDS Behav
January 2025
Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA, USA.
This study assessed disparities in pre-exposure prophylaxis (PrEP) use among transgender and gender expansive youth and young adults (N = 477) between 15 and 24 years old in the CARES (ATN 149) and TechStep (ATN 160) study protocols within the National Adolescent Medicine Trials Network for HIV/AIDS Interventions (ATN). Structural equation modeling was used to test mediation pathways between gender identity and PrEP uptake among the full sample and stratified by sex assigned at birth. Lifetime PrEP uptake was higher among those assigned male at birth (26%) versus assigned female at birth (9%), explained by greater structural and behavioral risks and perceived need for PrEP, especially among trans women.
View Article and Find Full Text PDFJ Pediatr Orthop
January 2025
Department of Pediatric Orthopaedics, Rainbow Babies and Children's Hospital at Case Western Reserve University.
Background: The recently described Modified Fels wrist skeletal maturity system (mFels wrist SMS) allows for accurate skeletal maturity estimation using a single anteroposterior wrist radiograph but requires evaluation of 8 parameters. A faster method may have clinical utility in the outpatient setting.
Methods: The 8 anteroposterior wrist radiographic parameters comprising the mFels wrist SMS were analyzed in 80 children.
Sci Rep
January 2025
Department of Counseling, Faculty of Educational Sciences and Psychology, University of Mohaghegh Ardabili, Ardabil, Iran.
The objective of the present study was to predict drug use among Iranian students on the basis of alexithymia, gender, age, and the mediating role of emotion regulation difficulty. This research employed a descriptive-correlational approach (structural equation modeling). The statistical population included 400 high school students studying during the 2023-2024 academic year in the cities of Khorramabad and Ardabil.
View Article and Find Full Text PDFJ Acad Nutr Diet
January 2025
Division of Research and Evaluation, Public Health Foundation Enterprises WIC Program, a program of Heluna Health. Electronic address:
Background: The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) provides benefits redeemable for select healthy foods, aligned with the Dietary Guidelines for Americans, to support healthy diets among pregnant and postpartum women, and their children to age 5 years, living in low-income households. WIC benefits are often not fully redeemed, limiting nutritional benefits of participation.
Objective: The objective of this study was to assess the associations of WIC participant, caregiver, and household characteristics with WIC food benefit redemption.
Utilizing the periodic pixel configuration of the CCD/CMOS imaging sensor as the reference grating and the image of the real grating formed by the lens as the specimen grating, the CCD Moiré method directly outputs amplified Moiré fringes, facilitating high-resolution, full-field deformation measurement. Due to the amplification effect of CCD Moiré, even minor relative rotations of the two gratings can significantly affect Moiré imaging and introduce measurable errors. This paper mainly addresses the imaging and measurement challenges of in-plane rotation in the CCD Moiré method.
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