Efficient magneto-optical trapping of Yb atoms with a violet laser diode

We report the first efficient trapping of rare-earth Yb atoms with a high-power violet laser diode (LD). An injection-locked violet LD with a 25 mW frequency-stabilized output was used for the magneto-optical trapping (MOT) of fermionic as well as bosonic Yb isotopes. A typical number of $4\times 10^6$ atoms for $^{174}$Yb with a trap density of $\sim 1\times10^8/$cm$^3$ was obtained. A 10 mW violet external-cavity LD (ECLD) was used for the one-dimensional (1D) slowing of an effusive Yb atomic beam without a Zeeman slower resulting in a 35-fold increase in the number of trapped atoms. The overall characteristics of our compact violet MOT, e.g., the loss time of 1 s, the loading time of 400 ms, and the cloud temperature of 0.7 mK, are comparable to those in previously reported violet Yb MOTs, yet with a greatly reduced cost and complexity of the experiment.Comment: 5 pages, 3 figures, 1 table, Phys. Rev. A (to be published

Cold atom Clocks and Applications

This paper describes advances in microwave frequency standards using laser-cooled atoms at BNM-SYRTE. First, recent improvements of the $^{133}$Cs and $^{87}$Rb atomic fountains are described. Thanks to the routine use of a cryogenic sapphire oscillator as an ultra-stable local frequency reference, a fountain frequency instability of $1.6\times 10^{-14}\tau^{-1/2}$ where $\tau$ is the measurement time in seconds is measured. The second advance is a powerful method to control the frequency shift due to cold collisions. These two advances lead to a frequency stability of $2\times 10^{-16}$ at $50,000s for the first time for primary standards. In addition, these clocks realize the SI second with an accuracy of$7\times 10^{-16}$, one order of magnitude below that of uncooled devices. In a second part, we describe tests of possible variations of fundamental constants using$^{87}$Rb and$^{133}$Cs fountains. Finally we give an update on the cold atom space clock PHARAO developed in collaboration with CNES. This clock is one of the main instruments of the ACES/ESA mission which is scheduled to fly on board the International Space Station in 2008, enabling a new generation of relativity tests.Comment: 30 pages, 11 figure

On the external forcing of global eruptive activity in the past 300 years

The decryption of the temporal sequence of volcanic eruptions is a key step in better anticipating future events. Volcanic activity is the result of a complex interaction between internal and external processes, with time scales spanning multiple orders of magnitude. We review periodicities that have been detected or correlated with volcanic eruptions/phenomena and interpreted as resulting from external forces. Taking a global perspective and longer time scales than a few years, we approach this interaction by analyzing three time series using singular spectral analysis: the global number of volcanic eruptions (NVE) between 1700 and 2022, the number of sunspots (ISSN), a proxy for solar activity, the polar motion (PM) and length of day (lod), two proxies for gravitational force. Several pseudo-periodicities are common to NVE and ISSN, in addition to the 11-year Schwabe cycle that has been reported in previous work, but NVE shares even more periodicities with PM. These quasi-periodic components range from ~5 to ~130 years. We interpret our analytical results in light of the Laplace's paradigm and propose that, similarly to the movement of Earth's rotation axis, global eruptive activity is modulated by commensurable orbital moments of the Jovian planets, whose influence is also detected in solar activity

How and when plume zonation appeared during the 132 Myr evolution of the Tristan Hotspot

Increasingly, spatial geochemical zonation, present as geographically distinct, subparallel trends, is observed along hotspot tracks, such as Hawaii and the Galapagos. The origin of this zonation is currently unclear. Recently zonation was found along the last B70 Myr of the Tristan-Gough hotspot track. Here we present new Sr–Nd–Pb–Hf isotope data from the older parts of this hotspot track (Walvis Ridge and Rio Grande Rise) and re-evaluate published data from the Etendeka and Parana flood basalts erupted at the initiation of the hotspot track. We show that only the enriched Gough, but not the less-enriched Tristan, component is present in the earlier (70–132 Ma) history of the hotspot. Here we present a model that can explain the temporal evolution and origin of plume zonation for both the Tristan-Gough and Hawaiian hotspots, two end member types of zoned plumes, through processes taking place in the plume sources at the base of the lower mantle

Differential expression of follistatin and FLRG in human breast proliferative disorders

<p>Abstract</p> <p>Background</p> <p>Activins are growth factors acting on cell growth and differentiation. Activins are expressed in high grade breast tumors and they display an antiproliferative effect inducing G0/G1 cell cycle arrest in breast cancer cell lines. Follistatin and follistatin- related gene (FLRG) bind and neutralize activins. In order to establish if these activin binding proteins are involved in breast tumor progression, the present study evaluated follistatin and FLRG pattern of mRNA and protein expression in normal human breast tissue and in different breast proliferative diseases.</p> <p>Methods</p> <p>Paraffin embedded specimens of normal breast (NB - n = 8); florid hyperplasia without atypia (FH - n = 17); fibroadenoma (FIB - n = 17); ductal carcinoma <it>in situ </it>(DCIS - n = 10) and infiltrating ductal carcinoma (IDC - n = 15) were processed for follistatin and FLRG immunohistochemistry and <it>in situ </it>hybridization. The area and intensity of chromogen epithelial and stromal staining were analyzed semi-quantitatively.</p> <p>Results</p> <p>Follistatin and FLRG were expressed both in normal tissue and in all the breast diseases investigated. Follistatin staining was detected in the epithelial cytoplasm and nucleus in normal, benign and malignant breast tissue, with a stronger staining intensity in the peri-alveolar stromal cells of FIB at both mRNA and protein levels. Conversely, FLRG area and intensity of mRNA and protein staining were higher both in the cytoplasm and in the nucleus of IDC epithelial cells when compared to NB, while no significant changes in the stromal intensity were observed in all the proliferative diseases analyzed.</p> <p>Conclusion</p> <p>The present findings suggest a role for follistatin in breast benign disease, particularly in FIB, where its expression was increased in stromal cells. The up regulation of FLRG in IDC suggests a role for this protein in the progression of breast malignancy. As activin displays an anti-proliferative effect in human mammary cells, the present findings indicate that an increased FST and FLRG expression in breast proliferative diseases might counteract the anti-proliferative effects of activin in human breast cancer.</p