Pulsing the different operation phases of a vapor-cell clock (optical pumping, interrogation, and detection) has been recognized as one of the most effective techniques to reduce light shift and then to improve the stability perspectives of vapor cell clocks. However, in order to take full advantage of the pulsed scheme, a fast-gated electronics is required, the times involved being of the order of milliseconds. In this paper we describe the design and the implementation of the electronics that synchronizes the different phases of the clock operation, as well as of the electronics that is mainly devoted to the thermal stabilization of the clock physics package. We also report some characterization measurements, including a measurement of the clock frequency stability. In particular, in terms of Allan deviation, we measured a frequency stability of 1.2 x 10(-12) tao(-1/2) for averaging times up to tao = 10(5) s, a very interesting result by itself and also for a possible space application of such a clock.
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http://dx.doi.org/10.1109/tuffc.2007.458 | DOI Listing |
mBio
January 2025
Department of Microbiology, UMass Chan Medical School, Worcester, Massachusetts, USA.
Unlabelled: (Mtb) exhibits an impressive ability to adapt to rapidly changing environments, despite its genome's apparent stability. Recently, phase variation through indel formation in homopolymeric tracts (HT) has emerged as a potentially important mechanism promoting adaptation in Mtb. This study examines the impact of common phase variants associated with the ESX-1 type VII secretion system, focusing on a highly variable HT upstream of the ESX-1 regulatory factor, .
View Article and Find Full Text PDFChemistry
January 2025
The Hong Kong Polytechnic University, Department of Applied Biology and Chemical Technology, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Hom, Hong Kong (P.R. China), 000000, Hong Kong, HONG KONG.
A series of new (donor)₂-donor-π-acceptor (D2-D-π-A) and (acceptor)₂-donor-π-acceptor (A2-D-π-A) organic photosensitizers based on the framework of (Z)-2-cyano-3-(5-(4-(diphenylamino)phenyl)thiophen-2-yl)acrylic acid have been synthesized and characterized. By incorporating groups with different electron-donating or withdrawing abilities, such as dibenzothiophene (DBT), dibenzofuran (DBF), and triazine (TA), into the triphenylamine segment, their photophysical properties have been regulated. Theoretical calculations were used to explore how various donor-acceptor combinations influence their hydrogen production performance.
View Article and Find Full Text PDFGlob Chang Biol
January 2025
Scripps Institution of Oceanography, UC San Diego, La Jolla, California, USA.
High spatial or temporal variability in community composition makes it challenging for natural resource managers to predict ecosystem trajectories at scales relevant to management. This is commonly the case in nearshore marine environments, where the frequency and intensity of disturbance events vary at the sub-kilometer to meter scale, creating a patchwork of successional stages within a single ecosystem. The successional stage of a community impacts its stability, recovery potential, and trajectory over time in predictable ways.
View Article and Find Full Text PDFJ Pain Res
January 2025
Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
Purpose: Spinal cord stimulation (SCS) is pivotal in treating chronic intractable pain. To elucidate the mechanism of action among conventional and current novel types of SCSs, a stable and reliable electrophysiology model in the consensus animals to mimic human SCS treatment is essential. We have recently developed a new in vivo implantable pulsed-ultrahigh-frequency (pUHF) SCS platform for conducting behavioral and electrophysiological studies in rats.
View Article and Find Full Text PDFPNAS Nexus
January 2025
Department of Biochemistry, University of Geneva, 1211 Geneva, Switzerland.
The microtubule cytoskeleton is a dynamic network essential for many cellular processes, influenced by physicochemical factor, such as temperature, pH, dimer concentration, and ionic environment. In this study, we used in vitro reconstitution assays to examine the effects of four monovalent ions (Na, K, Cl, and Ac) on microtubule dynamics, uncovering distinct effects for each ion. Na was found to increase microtubule dynamicity by raising catastrophe frequency, polymerization and depolymerization speeds, and ultimately reducing microtubule lifetime by 80%.
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