Interferometric length metrology for the dimensional control of ultra-stable Ring Laser Gyroscopes

We present the experimental test of a method for controlling the absolute length of the diagonals of square ring laser gyroscopes. The purpose is to actively stabilize the ring cavity geometry and to enhance the rotation sensor stability in order to reach the requirements for the detection of the relativistic Lense-Thirring effect with a ground-based array of optical gyroscopes. The test apparatus consists of two optical cavities 1.32 m in length, reproducing the features of the ring cavity diagonal resonators of large frame He-Ne ring laser gyroscopes. The proposed measurement technique is based on the use of a single diode laser, injection locked to a frequency stabilized He-Ne/Iodine frequency standard, and a single electro-optic modulator. The laser is modulated with a combination of three frequencies allowing to lock the two cavities to the same resonance frequency and, at the same time, to determine the cavity Free Spectral Range (FSR). We obtain a stable lock of the two cavities to the same optical frequency reference, providing a length stabilization at the level of 1 part in $10^{11}$, and the determination of the two FSRs with a relative precision of 0.2 ppm. This is equivalent to an error of 500 nm on the absolute length difference between the two cavities

POS1221 SARS-COV2 SEROLOGY SCREENING IN SPONDYLOARTHRITIS PATIENTS IN NORTH-EASTERN ITALY: A PILOT STUDY

Background:Serology could help defining the real extent of Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV2) diffusion in the population, especially in individuals considered at higher risk of SARS-CoV2 infection (COVID-19), such as Spondiloarthritis (SpA) patients undergoing immunosuppressive therapy or health care workers (HCW). In fact, COVID-19 detection is complicated by the fact that many patients can be asymptomatic. In these cases, it has also been suggested that a weaker immune response might be elicited.In this context, the role of anti-cytokine targeted therapy –commonly used as treatment in SpA- is uncertain, as it is not clear whether it is detrimental or protective towards severe disease forms.Objectives:The aim of the study was to explore the potential role of serology in detecting previous contact with SARS-CoV2 in SpA patients and HCW, and compare the frequency of positive findings with a control population.Methods:Consecutive patients affected by axial or peripheral SpA, classified according to Assessment of SpondyloArthritis international Society (ASAS) criteria and undergoing cytokine-targeted therapy, as well as HCW and controls from the pre-COVID-19 era (control group, 2015) were recruited. In SpA patients, disease activity was assessed by Ankylosing Spondylitis Disease Activity Score (ASDAS) and Disease Activity Score on 28-joint-count (DAS28).Sera from all patients were analysed through chemiluminescent analytical system (CLIA) for the presence of IgG and IgM anti-SARS-CoV2. Patients with a positive serological test (either IgM or IgG) additionally underwent real time Polymerase Chain Reaction (RT-PCR) in nasopharyngeal swabs in order to test for active infection. In SpA patients, serology was repeated after 3 months. Data across the 3 groups were compared by ANOVA or Chi-square, while comparison between 2 groups were conducted by Wilcoxon signed rank test or Chi-Square, for continuous and categorical data respectively. P ≤ 0.05 were considered as significant.Results:A total of 396 patients were recruited: 200 SpA, 95 HCW and 101 healthy controls. SpA patients were mostly (54%) males, with mean age 49.6 ±14.7 years, and all were treated with anti-TNFα (78%), anti-IL-17 (9%) and anti-IL-23 drugs (7%), or small molecules (6%). Their disease activity level was moderate-low as assessed by ASDAS (1.95 ±0.98) and DAS28 (2.33 ±2.02). Among HCW and controls, 35% and 62% were male, with mean age 46.7 ±12.9 and 50.6±10.6 respectively.Positive serology (IgM or IgG, or both) was found in 12.5% SpA patients, 8.4% HCW, 0% controls (p=0.001). Among these, IgM titres were higher in the SpA group than in HCW (2.76±2.94 versus 0.80±0.67 KU/L, p= 0.016), while IgG mean titres were lower in the SpA group than in HCW (0.88±3.18 KU/L versus 1.05±0.88, p= 0.035). SpA patients with positive serology more frequently reported COVID-19 like symptoms than those with negative serology (20% vs 4%, p=0.009) and 2 had COVID-19 as confirmed by RT-PCR, none with a severe disease course. None of the HCW reported symptoms or tested positive by RT-PCR. In the SpA patients, at 3 months, the mean IgM titre decreased from 2.76±2.93 to 2.38±2.95 (p=0.001), while the IgG titres decreased from 0.89±3.25 to 0.31±0.87 (p=ns). Interestingly, the IgM or IgG titer at a single-patient level did not seem to change much in terms of absolute value (Figure 1), except in one patient, with documented COVID-19 (positive RT-PCR), in whom IgG level even decreased at 3 months.Conclusion:Serology revealed that exposure to COVID-19 in SpA patients, as well as HCW, was higher than expected based on reported symptoms. Targeted anti-cytokine therapy could act as a protective factor for a severe disease course in SpA patients. However, in this population, IgG and IgM titres did not change in a clinically significant manner at 3 months, and patient did not seem to develop an immune profile consistent with durable response. This result could be due to a weaker immune response in mild infections, but further studies are warranted to clarify the pathophysiology beyond these observations.Figure 1.Disclosure of Interests:Augusta Ortolan: None declared, Chiara Cosma: None declared, Mariagrazia Lorenzin: None declared, Giacomo Cozzi: None declared, Andrea Doria Speakers bureau: Novartis, Abbvie, Pfizer, MSD, Janssen, Glaxosmithkline, Mario Plebani: None declared, Roberta Ramonda Speakers bureau: Novartis, Abbvie, Pfizer, MSD, Jansse

Searching for galactic axions through magnetized media: QUAX status report

The current status of the QUAX R\&D program is presented. QUAX is a feasibility study for a detection of axion as dark matter based on the coupling to the electrons. The relevant signal is a magnetization change of a magnetic material placed inside a resonant microwave cavity and polarized with a static magnetic field.Comment: Contributed to the 13th Patras Workshop on Axions, WIMPs and WISPs, Thessaloniki, May 15 to 19, 201

Axion search with a quantum-limited ferromagnetic haloscope

A ferromagnetic axion haloscope searches for Dark Matter in the form of axions by exploiting their interaction with electronic spins. It is composed of an axion-to-electromagnetic field transducer coupled to a sensitive rf detector. The former is a photon-magnon hybrid system, and the latter is based on a quantum-limited Josephson parametric amplifier. The hybrid system consists of ten 2.1 mm diameter YIG spheres coupled to a single microwave cavity mode by means of a static magnetic field. Our setup is the most sensitive rf spin-magnetometer ever realized. The minimum detectable field is $5.5\times10^{-19}\,$T with 9 h integration time, corresponding to a limit on the axion-electron coupling constant $g_{aee}\le1.7\times10^{-11}$ at 95% CL. The scientific run of our haloscope resulted in the best limit on DM-axions to electron coupling constant in a frequency span of about 120 MHz, corresponding to the axion mass range $42.4$-$43.1\,\mu$eV. This is also the first apparatus to perform an axion mass scanning by changing the static magnetic field.Comment: 4 pages, 4 figure

A laser gyroscope system to detect the Gravito-Magnetic effect on Earth

Large scale square ring laser gyros with a length of four meters on each side are approaching a sensitivity of 1x10^-11 rad/s/sqrt(Hz). This is about the regime required to measure the gravitomagnetic effect (Lense Thirring) of the Earth. For an ensemble of linearly independent gyros each measurement signal depends upon the orientation of each single axis gyro with respect to the rotational axis of the Earth. Therefore at least 3 gyros are necessary to reconstruct the complete angular orientation of the apparatus. In general, the setup consists of several laser gyroscopes (we would prefer more than 3 for sufficient redundancy), rigidly referenced to each other. Adding more gyros for one plane of observation provides a cross-check against intra-system biases and furthermore has the advantage of improving the signal to noise ratio by the square root of the number of gyros. In this paper we analyze a system of two pairs of identical gyros (twins) with a slightly different orientation with respect to the Earth axis. The twin gyro configuration has several interesting properties. The relative angle can be controlled and provides a useful null measurement. A quadruple twin system could reach a 1% sensitivity after 3:2 years of data, provided each square ring has 6 m length on a side, the system is shot noise limited and there is no source for 1/f- noise.Comment: 9 pages, 6 figures. 2010 Honourable mention of the Gravity Research Foundation; to be published on J. Mod. Phys.

Feedback cooling of the normal modes of a massive electromechanical system to submillikelvin temperature

We apply a feedback cooling technique to simultaneously cool the three electromechanical normal modes of the ton-scale resonant-bar gravitational wave detector AURIGA. The measuring system is based on a dc Superconducting Quantum Interference Device (SQUID) amplifier, and the feedback cooling is applied electronically to the input circuit of the SQUID. Starting from a bath temperature of 4.2 K, we achieve a minimum temperature of 0.17 mK for the coolest normal mode. The same technique, implemented in a dedicated experiment at subkelvin bath temperature and with a quantum limited SQUID, could allow to approach the quantum ground state of a kilogram-scale mechanical resonator.Comment: 4 pages, 4 figure

SAT0245 RENAL INVOLVEMENT AT ONSET IN ANTI-NEUTROPHIL CYTOPLASMIC ANTIBODY (ANCA)-ASSOCIATED VASCULITIS: A MAJOR INDEPENDENT RISK FACTOR FOR RENAL RELAPSE

Background:In ANCA-associated vasculitis (AAV), renal relapses are cause for concern as they are unpredictable and predictors of end-stage renal disease (ESRD).Objectives:We aimed to assess the frequency of major renal (MR) relapses in AAV in our cohort and identify independent predictors of the first MR relapse at diagnosis.Methods:We performed a retrospective monocentric observational study in our Vasculitis clinic from January 2000 to August 2019. Inclusion criteria were: 1) granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and limited kidney disease (LKD) diagnosis fulfilling EMA algorithm criteria; 2) achievement of a stable remission, defined as absence of vasculitis symptoms or signs and adherence to the prednisone taper during remission-induction treatment. We excluded patients who developed ESRD before remission and those with incomplete data during the follow-up. Major renal (MR) relapses were defined as occurrence of at least one major item of renal Birmingham Vasculitis Activity Score version 3 (BVASv3).All remitted patients were allocated in two subgroups: patients without MR relapse and patients with MR relapse. Univariate and multivariable analysis of first MR relapse predictors was performed with Fine and Gray (F&G) sub distribution hazards model to assess all competitive risks (progression to ESRD without MR relapse and death before MR relapse). Due to the relatively low frequency of events and the risk of overfitting, we performed several multivariable models with three variables, as recommended by Peduzzi e al1. The best multivariable model was selected accordingly to the Akaike information criterion (AIC).Results:96 (53% females) patients met the inclusion criteria: 74 GPA, 21 MPA and 1 LKD. Median age at diagnosis was 54 (44-64) years. ANCA testing was present in 94 patients, 85 were ANCA positive: 56 c-ANCA/PR3, 28 p-ANCA/MPO and 1 double positivity.During a median follow-up (FU) of 54.5 months (29.3-96.5), we observed 19 MR relapses in 17 patients while 2 patients progressed to ESRD, 3 died without events and 76 reported no MR relapse. Density-incidence of MR relapses since remission was 3.6/100 person-year (CI 95% 2.2-5.6). Median time to first MR relapse after remission was 33 months (14-67.5).At first MR relapse, 8 (53.3%) patients were on steroids while 10 (66.7%) were on immunosuppressant (5 azathioprine, 5 mycophenolate). In 2 cases, data about remission-maintenance treatment was not available.MR relapses were observed only in ANCA positive patients with a significantly higher frequency of skin, kidney and nerve involvement at diagnosis (41.2% vs 17.7%, p=0.034, 94.1% vs 57.0% p=0.004, and 52.9% vs 25.3% p=0.024, respectively); while Ear, Nose and Throat (ENT) involvement was significantly lower (35.3% vs 62.0% p=0.043). Mean BVASv3 at diagnosis scored significantly higher in MR relapse group (24.1±6.2 vs 18.1±8.1. p=0.007).At multivariable analysis with F&G model, renal involvement and induction treatment without cyclophosphamide and/or Rituximab at diagnosis were independent predictors of MR relapse (sHR 20.4 (2.6-158.2), p=0.004 and sHR 4.2 (1.5-12.0), p=0.007, respectively). Moreover, there was a trend of higher risk of MR relapse in PR3-ANCA (sHR 2.5 (0.9-7.1), p=0.091).Conclusion:Renal involvement at diagnosis and milder remission-induction treatment regimens resulted in a significantly higher risk of MR relapse during the FU in our cohort. PR3-ANCA specificity was not an independent predictor of MR relapse, even if we observed a trend of higher MR relapse risk with this covariate.References:[1]Peduzzi P et al. A simulation study of the number of events per variable in logistic regression analysis. J Clin Epidemiol. 1996;49(12):1373-9.Disclosure of Interests:Mara Felicetti: None declared, Augusta Ortolan: None declared, Anna Chiara Frigo: None declared, Roberto Padoan: None declared, Michela Gasparotto: None declared, Mariagrazia Lorenzin: None declared, Andrea Doria Consultant of: GSK, Pfizer, Abbvie, Novartis, Ely Lilly, Speakers bureau: UCB pharma, GSK, Pfizer, Janssen, Abbvie, Novartis, Ely Lilly, BMS, Roberta Ramonda Speakers bureau: Novartis, Celgene, Janssen, Pfizer, Abbvie, Lilly, Franco Schiavon: None declare

Modulation of LISA free-fall orbits due to the Earth-Moon system

We calculate the effect of the Earth-Moon (EM) system on the free-fall motion of LISA test masses. We show that the periodic gravitational pulling of the EM system induces a resonance with fundamental frequency 1 yr^-1 and a series of periodic perturbations with frequencies equal to integer harmonics of the synodic month (9.92 10^-7 Hz). We then evaluate the effects of these perturbations (up to the 6th harmonics) on the relative motions between each test masses couple, finding that they range between 3mm and 10pm for the 2nd and 6th harmonic, respectively. If we take the LISA sensitivity curve, as extrapolated down to 10^-6 Hz, we obtain that a few harmonics of the EM system can be detected in the Doppler data collected by the LISA space mission. This suggests that the EM system gravitational near field could provide an absolute calibration for the LISA sensitivity at very low frequencies.Comment: 15 pages, 5 figure