Ultrashort laser pulses have thus far been used in two distinct modes. In the time domain, the pulses have allowed probing and manipulation of dynamics on a subpicosecond time scale. More recently, phase stabilization has produced optical frequency combs with absolute frequency reference across a broad bandwidth. Here we combine these two applications in a spectroscopic study of rubidium atoms. A wide-bandwidth, phase-stabilized femtosecond laser is used to monitor the real-time dynamic evolution of population transfer. Coherent pulse accumulation and quantum interference effects are observed and well modeled by theory. At the same time, the narrow linewidth of individual comb lines permits a precise and efficient determination of the global energy-level structure, providing a direct connection among the optical, terahertz, and radio-frequency domains. The mechanical action of the optical frequency comb on the atomic sample is explored and controlled, leading to precision spectroscopy with an appreciable reduction in systematic errors.
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http://dx.doi.org/10.1126/science.1105660 | DOI Listing |
Acad Radiol
January 2025
Department of Radiology, Eye & ENT Hospital of Fudan University, 83 Fenyang Road, Shanghai 200031, China (Q.X.). Electronic address:
Rationale And Objectives: Alzheimer's disease (AD) is the most common pathogenesis of dementia, and mild cognitive impairment (MCI) is considered as the intermediate stage from normal elderly to AD. Early detection of MCI is an essential step for the timely intervention of AD to slow the progression of this disease. Different form previous studies in the whole-brain spontaneous activities, this research aimed to explore the low-frequency amplitude spectrum activities of patients with MCI within the default mode network (DMN), which has been involved in the process of maintaining normal cognitive function.
View Article and Find Full Text PDFSci Total Environ
January 2025
College of Environment and Ecology, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, China. Electronic address:
The increasing frequency of cyanobacterial blooms, particularly those induced by Microcystis aeruginosa (M. aeruginosa), poses severe economic, ecological and health challenges due to the production of microcystins (MCs). Environmental parameters such as light and nutrient availability influence MCs production, while the role of dissolved organic matter (DOM) photochemical processes in regulating these remains unclear.
View Article and Find Full Text PDFPain Rep
February 2025
Department of Occupational Therapy, Graduate School of Rehabilitation Science, Osaka Metropolitan University, Osaka, Japan.
Introduction: Chronic low back pain (CLBP) is a global health issue, and its nonspecific causes make treatment challenging. Understanding the neural mechanisms of CLBP should contribute to developing effective therapies.
Objectives: To compare current source density (CSD) and functional connectivity (FC) extracted from resting electroencephalography (EEG) between patients with CLBP and healthy controls and to examine the correlations between EEG indices and symptoms.
Mater Today Bio
February 2025
Department of Hepatobiliary Surgery, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China.
Acute pancreatitis (AP) is a highly fatal pancreatic inflammation. In recent years, synthetic nanoparticles have been extensively developed as drug carriers to address the challenges of systemic adverse reactions and lack of specificity in drug delivery. However, systemically administered nanoparticle therapy is rapidly cleared from circulation by the mononuclear phagocyte system (MPS), leading to suboptimal drug concentrations in inflamed tissues and suboptimal pharmacokinetics.
View Article and Find Full Text PDFHeliyon
July 2024
Department of Physics, University of Lucknow, Lucknow 226007, India.
In this paper, the dielectric behaviour of coconut oil within the frequency range 100 kHz to 30 MHz between temperature 30 °C-50 °C has been observed. The measured values of the dielectric constant and dielectric loss show notable variation with frequency and temperature for pure coconut oil. It is noticed that the dielectric constant (՛) and dielectric loss (՛՛) of coconut oil decreases with increasing temperature.
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