Large 2D Coulomb crystals in a radio frequency surface ion trap

We designed and operated a surface ion trap, with an ion-substrate distance of 500\mum, realized with standard printed-circuit-board techniques. The trap has been loaded with up to a few thousand Sr+ ions in the Coulomb-crystal regime. An analytical model of the pseudo-potential allowed us to determine the parameters that drive the trap into anisotropic regimes in which we obtain large (N>150) purely 2D ion Coulomb crystals. These crystals may open a simple and reliable way to experiments on quantum simulations of large 2D systems.Comment: 4 pages, 4 figure

Microcharacterization of Fluid Inclusions in Minerals by Raman Microprobe

Fluids trapped in inclusions in minerals are micro-amounts of ore-forming media composed of water, dissolved salts, gases and sometimes liquefied gases, liquid, hydrocarbons and solids. The aim of this paper is to summarize the contribution of the Raman scattering microspectrometry to the knowledge of fluid inclusions. After a review of the composition of fluid inclusions and a short presentation of microthermometrical investigations, a description of the Raman microprobe is given. Applications are reviewed; identification of ionic species dissolved in aqueous phase, characterization of gases of C-O-H-N-S system, identification of solids and non aqueous liquids. The complementary characteristics of Raman microanalysis and microthermometry are underlined. The last section is devoted to comparisons with other microprobes from the point of view of chemical and mineralogical analysis of fluid inclusions

Double-lambda microscopic model for entangled light generation by four-wave-mixing

Motivated by recent experiments, we study four-wave-mixing in an atomic double-{\Lambda} system driven by a far-detuned pump. Using the Heisenberg-Langevin formalism, and based on the microscopic properties of the medium, we calculate the classical and quantum properties of seed and conju- gate beams beyond the linear amplifier approximation. A continuous variable approach gives us access to relative-intensity noise spectra that can be directly compared to experiments. Restricting ourselves to the cold-atom regime, we predict the generation of quantum-correlated beams with a relative-intensity noise spectrum well below the standard quantum limit (down to -6 dB). Moreover entanglement between seed and conjugate beams measured by an inseparability down to 0.25 is expected. This work opens the way to the generation of entangled beams by four-wave mixing in a cold atomic sample.Comment: 11 pages, 6 figures, submitted to PR

Photoionisation loading of large Sr+ ion clouds with ultrafast pulses

This paper reports on photoionisation loading based on ultrafast pulses of singly-ionised strontium ions in a linear Paul trap. We take advantage of an autoionising resonance of Sr neutral atoms to form Sr+ by two-photon absorption of femtosecond pulses at a wavelength of 431nm. We compare this technique to electron-bombardment ionisation and observe several advantages of photoionisation. It actually allows the loading of a pure Sr+ ion cloud in a low radio-frequency voltage amplitude regime. In these conditions up to 4x10^4 laser-cooled Sr+ ions were trapped

Gem corundum deposits in Vietnam

Since 1983, gem-quality rubies have been recovered from the Luc Yen and Quy Chau mining areas in northern Vietnam. Since 1991, 'basaltic'-type blue-green-yellow ('BGY') sapphires have been mined in southern Vietnam. This article briefly reviews the history and geology of these different areas and shows the importance of marble and basalt-type deposits. Other types of corundum occurrences are found in amphibolite, pegmatite, gneiss and metasomatite. The gemmological, chemical and isotopic characteristics of these different types of corundum are described.<br /> The most notable features of rubies contained in marbles are that many crystals have blue colour zones, and inclusions of rutile, anhydrite and salts. The primary fluid inclusions are composed of carbon dioxide and hydrogen sulphide with native sulphur and diaspore daughter minerals. Sapphires from placers in basalts are characterized by inclusions of columbite, pyrochlore and baddeleyite. The trace element contents of corundums allow distinction of rubies in marbles from sapphires in basalts and metamorphic rocks. Rubies have high chromium (0.54<Cr<sub>2</sub>O<sub>3</sub><O.66 wt.%)and low iron (0.01<FeO<0.07 wt.%) contents. The geological origin of Vietnam corundums can be clearly determined from the isotopic composition of their structural oxygen, i.e. δ 18O = 21.0 ± 0.9% for rubies in marbles and δ 18O = 6.6 ± 0.4% for sapphires in basalts

Nonadhesive Culture System as a Model of Rapid Sphere Formation with Cancer Stem Cell Properties

BACKGROUND: Cancer stem cells (CSCs) play an important role in tumor initiation, progression, and metastasis and are responsible for high therapeutic failure rates. Identification and characterization of CSC are crucial for facilitating the monitoring, therapy, or prevention of cancer. Great efforts have been paid to develop a more effective methodology. Nevertheless, the ideal model for CSC research is still evolving. In this study, we created a nonadhesive culture system to enrich CSCs from human oral squamous cell carcinoma cell lines with sphere formation and to characterize their CSC properties further. METHODS: A nonadhesive culture system was designed to generate spheres from the SAS and OECM-1 cell lines. A subsequent investigation of their CSC properties, including stemness, self-renewal, and chemo- and radioresistance in vitro, as well as tumor initiation capacity in vivo, was also performed. RESULTS: Spheres were formed cost-effectively and time-efficiently within 5 to 7 days. Moreover, we proved that these spheres expressed putative stem cell markers and exhibited chemoradiotherapeutic resistance, in addition to tumor-initiating and self-renewal capabilities. CONCLUSIONS: Using this nonadhesive culture system, we successfully established a rapid and cost-effective model that exhibits the characteristics of CSCs and can be used in cancer research

Cell–cell and cell–matrix dynamics in intraperitoneal cancer metastasis

The peritoneal metastatic route of cancer dissemination is shared by cancers of the ovary and gastrointestinal tract. Once initiated, peritoneal metastasis typically proceeds rapidly in a feed-forward manner. Several factors contribute to this efficient progression. In peritoneal metastasis, cancer cells exfoliate into the peritoneal fluid and spread locally, transported by peritoneal fluid. Inflammatory cytokines released by tumor and immune cells compromise the protective, anti-adhesive mesothelial cell layer that lines the peritoneal cavity, exposing the underlying extracellular matrix to which cancer cells readily attach. The peritoneum is further rendered receptive to metastatic implantation and growth by myofibroblastic cell behaviors also stimulated by inflammatory cytokines. Individual cancer cells suspended in peritoneal fluid can aggregate to form multicellular spheroids. This cellular arrangement imparts resistance to anoikis, apoptosis, and chemotherapeutics. Emerging evidence indicates that compact spheroid formation is preferentially accomplished by cancer cells with high invasive capacity and contractile behaviors. This review focuses on the pathological alterations to the peritoneum and the properties of cancer cells that in combination drive peritoneal metastasis

DMTs and Covid-19 severity in MS: a pooled analysis from Italy and France

We evaluated the effect of DMTs on Covid-19 severity in patients with MS, with a pooled-analysis of two large cohorts from Italy and France. The association of baseline characteristics and DMTs with Covid-19 severity was assessed by multivariate ordinal-logistic models and pooled by a fixed-effect meta-analysis. 1066 patients with MS from Italy and 721 from France were included. In the multivariate model, anti-CD20 therapies were significantly associated (OR = 2.05, 95%CI = 1.39–3.02, p < 0.001) with Covid-19 severity, whereas interferon indicated a decreased risk (OR = 0.42, 95%CI = 0.18–0.99, p = 0.047). This pooled-analysis confirms an increased risk of severe Covid-19 in patients on anti-CD20 therapies and supports the protective role of interferon