Theory of double resonance magnetometers based on atomic alignment

We present a theoretical study of the spectra produced by optical-radio-frequency double resonance devices, in which resonant linearly polarized light is used in the optical pumping and detection processes. We extend previous work by presenting algebraic results which are valid for atomic states with arbitrary angular momenta, arbitrary rf intensities, and arbitrary geometries. The only restriction made is the assumption of low light intensity. The results are discussed in view of their use in optical magnetometers

A sound card based multi-channel frequency measurement system

For physical processes which express themselves as a frequency, for example magnetic field measurements using optically-pumped alkali-vapor magnetometers, the precise extraction of the frequency from the noisy signal is a classical problem. We describe herein a frequency measurement system based on an inexpensive commercially available computer sound card coupled with a software single-tone estimator which reaches Cram\'er--Rao limited performance, a feature which commercial frequency counters often lack. Characterization of the system and examples of its successful application to magnetometry are presented.Comment: 4 pages, 3 figures, 1 tabl

High Bandwidth Atomic Magnetometery with Continuous Quantum Non-demolition Measurements

We describe an experimental study of spin-projection noise in a high sensitivity alkali-metal magnetometer. We demonstrate a four-fold improvement in the measurement bandwidth of the magnetometer using continuous quantum non-demolition (QND) measurements. Operating in the scalar mode with a measurement volume of 2 cm^3 we achieve magnetic field sensitivity of 22 fT/Hz^(1/2) and a bandwidth of 1.9 kHz with a spin polarization of only 1%. Our experimental arrangement is naturally back-action evading and can be used to realize sub-fT sensitivity with a highly polarized spin-squeezed atomic vapor.Comment: 4 page

Experimental study of laser detected magnetic resonance based on atomic alignment

We present an experimental study of the spectra produced by optical/radio-frequency double resonance in which resonant linearly polarized laser light is used in the optical pumping and detection processes. We show that the experimental spectra obtained for cesium are in excellent agreement with a very general theoretical model developed in our group and we investigate the limitations of this model. Finally, the results are discussed in view of their use in the study of relaxation processes in aligned alkali vapors.Comment: 8 pages, 9 figures. Submitted to Phys. Rev. A. Related to physics/060523

Fresco Thermograph IC Inspection by Convective Heating Technique

Various Thermal/Infrared Non Destructive Testing techniques are gaining interest expanding the number of applications. The non-contact nature and the increased reliability of findings make this method particularly interesting for the works of art NDE. This work is devoted to the frescoes inspection for the sizing of detached plaster areas. Air filled voids in between the coloured plaster and the supporting wall are well identified due to the increased thermal resistance. Defects are evaluated from the evolution in time of the surface temperature detected by an IR camera in transient thermal regime. The inspection of large surfaces was recently and successfully applied by means of a lateral heating [1–2]. An advantage of this procedure is the reduced inspection time. This aspect is extremely important when the thermal diffusivity of the material is low, so that a long time is needed for the thermal signal appearance.</p

Automatic Procedure for Thermal NDE of Delaminations in CFRP by Using Neural Networks

This work is a first step in detecting and characterizing defects in an automatic way by using artificial intelligence. Transient thermal NDE by IR thermography is the method used for such a purpose. Data are processed by Neural Networks

Anti-phosphatidyl-serine/prothrombin antibodies (aPS/PT) in isolated lupus anticoagulant (LA): is their presence linked to dual test positivity?

Abstract Objectives Anti phosphatidylserine/prothrombin antibodies (aPS/PT) are often present in patients with antiphospholipid syndrome (APS) and might be relevant in the pathogenesis of this condition. They are major determinant of lupus anticoagulant (LA) in triple-positive antiphospholipid (aPL) profile. Whether they are present and pathogenic in patients with isolated LA [negative anticardiolipin (aCL) and anti β2-glycoprotein I (aβ2GPI) antibodies] is a matter of debate. Methods We measured aPS/PT in a large number of isolated LA with the aim to ascertain whether there is a link between the way isolated LA is assessed and the presence of these antibodies. APS/PT were measured in 86 patients with isolated LA (aCL- and abeta2GPI-). LA was assessed by two test systems, the dilute Russell Viper Venom Time (dRVVT) and the Silica Clotting Time (SCT). Results Sixty-six (77%) individuals with isolated LA were positive for aPS/PT (IgM 44, IgG and IgM 15, IgG in 7). Diagnosis of LA was made based on positive results in both dRVVT and SCT in 40 patients (Group 1) and based on only one positive test in the remaining 46 patients (Group 2). The rate of positive aPS/PT antibodies was significantly higher in Group 1 (OR=7.2, 95% CI 1.9–27.0, p<0.002). Moreover, the titre of IgM aPS/PT was significantly increased in Group 1 as compared to Group 2 (137 U, IQR 64–179 vs. 43 U, IQR 11–120, p=0.008). Conclusions These data indicate an association between LA based on two positive coagulation tests and the presence of aPS/PT antibodies, especially of IgM isotype

Lupus anticoagulant identifies two distinct groups of patients with different antibody patterns

Background: Whether antibodies directed to β2-Glycoprotein I (aβ2GPI) are responsible for LA activity is not well defined. However, in the absence of such antibodies the molecule responsible for LA phenomenon is unknown. Objective: The aim of this study was the biochemical identification of the target antigen epitope of aPL responsible of LA activity in the absence of aβ2GPI antibodies together with the biological and clinical characteristics of these patients in comparison with classical triple positive patients. Patients/methods: A comparison of patients with LA without (LA+/aβ2GPI−) and those with (LA+/aβ2GPI+) associated aβ2GPI antibodies was performed. Size exclusion chromatography and analytical chromatography were used to identify the molecule with LA activity in patients LA+/aβ2GPI-. Results and conclusions: Analytical size-exclusion chromatography revealed a peak of 996Kd with LA activity perfectly overlapping that of IgM anti phosphatidylserine/prothrombin (aPS/PT) antibodies. Similarly, all the 25 LA+/aβ2GPI− patients were positive for aPS/PT antibodies. LA+/aβ2GPI− compared to 33 LA+/aβ2GPI+ patients turned out to be significantly older, with a lower rate of previous thromboembolic events and a weaker LA activity. Search for aPS/PT and aβ2GPI antibodies in patients with LA is useful to identify two subgroups of LA at different risk of thromboembolic event