Analysis of ring laser gyroscopes including laser dynamics

Inertial sensors stimulate very large interest, not only for their application but also for fundamental physics tests. Ring laser gyros, which measure angular rotation rate, are certainly among the most sensitive inertial sensors, with excellent dynamic range and bandwidth. Large area ring laser gyros are routinely able to measure fractions of prad/s, with high duty cycle and bandwidth, providing fast, direct and local measurement of relevant geodetic and geophysical signals. Improvements of a factor $10-100$ would open the windows for general relativity tests, as the GINGER project, an Earth based experiment aiming at the Lense-Thirring test at $1\%$ level. However, it is well known that the dynamics of the laser induces non-linearities, and those effects are more evident in small scale instruments. Sensitivity and accuracy improvements are always worthwhile, and in general there is demand for high sensitivity environmental study and development of inertial platforms, where small scale transportable instruments should be used. We discuss a novel technique to analyse the data, aiming at studying and removing those non-linearity. The analysis is applied to the two ring laser prototypes GP2 and GINGERINO, and angular rotation rate evaluated with the new and standard methods are compared. The improvement is evident, it shows that the back-scatter problem of the ring laser gyros is negligible with a proper analysis of the data, improving the performances of large scale ring laser gyros, but also indicating that small scale instruments with sensitivity of nrad/s are feasible.Comment: 9 pages and 7 figure

First deep underground observation of rotational signals from an earthquake at teleseismic distance using a large ring laser gyroscope

Recent advances in large ring laser gyroscopes (RLG) technologies opened the possibility to observe rotations of the ground with sensitivities up to $10^{-11}$ $\frac{rad}{s}$ over the frequency band of seismological interest (0.01-1Hz), thus opening the way to a new geophysical discipline, i.e. rotational seismology. A measure of rotations in seismology is of fundamental interest for (a) the determination of all the six degrees of freedom that characterize a rigid body motion, and (b) the quantitative estimate of the rotational motions contaminating ground translation measurements obtained from standard seismometers. Within this framework, this paper presents and describes GINGERino, a new large observatory-class RLG located in Gran Sasso underground laboratory (LNGS), one national laboratories of the INFN (Istituto Nazionale di Fisica Nucleare). We also report unprecedented observations and analyses of the roto-translational signals from a tele-seismic event observed in such a deep underground environment

Measuring the Virgo area tilt noise with a laser gyroscope

We report on the measurements of tilt noise performed at the Virgo site with a ring laser gyroscope. The apparatus is a He-Ne laser operating in a square cavity mounted on a vertical plane perpendicular to the north-south arm of the inteferometer. We discuss the possibility of using the ring laser signal to improve the performances of the control system of the Virgo seismic suspensions. The comparison between the ring laser signal and the control signals for the longitudinal translations of the inverted pendulum (IP) shows remarkable coherence in the frequency range 20-200 mHz.Comment: 4 pages, Proceedings of 46th Rencontres de Morion

Prognostic role of intragastric cytopathology and microbiota in surgical patients with stomach cancer

In the last decade, analysis of malignant cells and flora in gastric lavage (GL) has provided interesting data on pathogenesis of gastric cancer (GC). For this study, combining such two aspects into one cyto-microbiologic category, we tested the prognostic role of the presence/absence of cancer cells (GL1/GL0) and bacterial microbiota (MB1/MB0) in our GC population. Material and Methods: Between April 2012 and August 2019, 79 surgical patients with GC were prospectively investigated with the determination of GL MB. Results: Compared with GL1 MB0, GL1 MB1 strongly correlated with advanced GC, portended poorer overall survival (OS) (45.8 months vs 20.5 months, P = 0.049), and resulted a significant (P = 0.008) and an independent (P = 0.013) prognostic factor unfavorable for OS. Conclusion: In the light of our results, the cyto-microbiologic parameter of GL MB should be used to gain a better prognosis of GC patients. Administration of antimicrobial treatment for MB1 subjects should be entertained because it could reduce the risk of oncogenesis

GINGER: A feasibility study

GINGER (Gyroscopes IN General Relativity) is a proposal for an Earth-based experiment to measure the Lense-Thirring (LT) and de Sitter effects. GINGER is based on ring lasers, which are the most sensitive inertial sensors to measure the rotation rate of the Earth. We show that two ring lasers, one at maximum signal and the other horizontal, would be the simplest configuration able to retrieve the GR effects. Here, we discuss this configuration in detail showing that it would have the capability to test LT effect at 1%, provided the accuracy of the scale factor of the instrument at the level of 1 part in 1012 is reached. In principle, one single ring laser could do the test, but the combination of the two ring lasers gives the necessary redundancy and the possibility to verify that the systematics of the lasers are sufficiently small. The discussion can be generalised to seismology and geodesy and it is possible to say that signals 10-12 orders of magnitude below the Earth rotation rate can be studied; the proposed array can be seen as the basic element of multi-axial systems, and the generalisation to three dimensions is feasible adding one or two devices and monitoring the relative angles between different ring lasers. This simple array can be used to measure with very high precision the amplitude of angular rotation rate (the length of the day, LOD), its short term variations, and the angle between the angular rotation vector and the horizontal ring laser. Finally this experiment could be useful to probe gravity at fundamental level giving indications on violations of Einstein Equivalence Principle and Lorenz Invariance and possible chiral effects in the gravitational field

Self-expandable metal stents for left sided colon obstruction from diverticulitis. A single center retrospective series

Background and Objectives: The incidence of diverticulitis is increasing in western countries. Complicated diverticulitis is defined as diverticulitis associated with localized or generalized perforation, localized or distant abscess, fistula, stricture or obstruction. Colonic symptomatic strictures are often treated with segmental colectomy. The aim of our study is to report our experience with Self Expandable Metal Stents (SEMS) placement to relieve sigmoid obstruction secondary to diverticulitis, either as a permanent solution or as a bridge to elective colectomy. Material and Methods: From January 2016 to December 2018, 21 patients underwent SEMS placement for sigmoid obstruction secondary to diverticulitis at our institution. In four patients with poor general conditions, SEMS was considered the definitive form of treatment. In 17 patients, the stent was placed as bridge to elective colectomy. Data were prospectively collected and retrospectively analyzed. Primary outcomes were postoperative mortality and morbidity after SEMS and subsequent elective colectomy. Results: There was no mortality or major morbidity after SEMS placement or subsequent elective colectomy. No stoma was performed. Conclusions: Placement of Colorectal Self Expandable Stent represents a useful tool to relieve obstruction in patients with left-sided colonic diverticulitis. SEMS placement makes it possible to transform an emergency clinical condition into an elective condition, giving time to resolve the inflammation and the infection inevitably associated with complicated diverticulitis

First deep underground observation of rotational signals from an earthquake at teleseismic distance using a large ring laser gyroscope

Recent advances in large ring laser gyroscopes (RLG) technologies opened the possibility to observe rotations of the ground with sensitivities up to 10 11 rad/sec over the frequency band of seismological interest (0.01-1Hz), thus opening the way to a new geophysical discipline, i.e. rotational seismology. A measure of rotations in seismology is of fundamental interest for (a) the determination of all the six degrees of freedom that characterize a rigid body’s motion, and (b) the quantitative estimate of the rotational motions contaminating ground translation measurements obtained from standard seismometers. Within this framework, this paper presents and describes GINGERino, a new large observatory-class RLG located in Gran Sasso underground laboratory (LNGS), one national laboratories of the INFN (Istituto Nazionale di Fisica Nucleare). We also report unprecedented observations and analyses of the roto-translational signals from a tele-seismic event observed in such a deep underground environment

Comparative analysis of local angular rotation between the Ring Laser Gyroscope GINGERINO and GNSS stations

The study of local deformations is a hot topic in geodesy. Local rotations of the crust around the vertical axis can be caused by deformations. In the Gran Sasso area the ring laser prototype GINGERINO and the GNSS array are operative. One year of data of GINGERINO is compared with the ones from the GNSS stations, homogeneously selected around the position of GINGERINO, aiming at looking for rotational signals with period of days common to both systems. At that purpose the rotational component of the area circumscribed by the GNSS stations has been evaluated and compared with the GINGERINO data. The coherences between the signals show structures that even exceed 60$\%$ coherence over the 6-60 days period; to validate this unprecedented analysis two different methods have been used to evaluate the local rotation using the GNSS stations. The analysis reveals that the shared rotational signal's amplitude in both instruments is approximately $10^{-13} rad/s$, an order of magnitude lower than the amplitudes of the signals examined using the coherence method. The ring laser array GINGER is at present under construction, and the confrontation of the ring laser data with GNSS antennas provides evidence of the fruibility and validity of the ring laser data for very low frequency investigation

Tunability and Losses of Mid-infrared Plasmonics in Heavily Doped Germanium Thin Films

Heavily-doped semiconductor films are very promising for application in mid-infrared plasmonic devices because the real part of their dielectric function is negative and broadly tunable in this wavelength range. In this work we investigate heavily n-type doped germanium epilayers grown on different substrates, in-situ doped in the $10^{17}$ to $10^{19}$ cm$^{-3}$ range, by infrared spectroscopy, first principle calculations, pump-probe spectroscopy and dc transport measurements to determine the relation between plasma edge and carrier density and to quantify mid-infrared plasmon losses. We demonstrate that the unscreened plasma frequency can be tuned in the 400 - 4800 cm$^{-1}$ range and that the average electron scattering rate, dominated by scattering with optical phonons and charged impurities, increases almost linearly with frequency. We also found weak dependence of losses and tunability on the crystal defect density, on the inactivated dopant density and on the temperature down to 10 K. In films where the plasma was optically activated by pumping in the near-infrared, we found weak but significant dependence of relaxation times on the static doping level of the film. Our results suggest that plasmon decay times in the several-picosecond range can be obtained in n-type germanium thin films grown on silicon substrates hence allowing for underdamped mid-infrared plasma oscillations at room temperature.Comment: 18 pages, 10 figure

Horizontal rotation signals detected by "G-Pisa" ring laser for the Mw=9.0, March 2011, Japan earthquake

We report the observation of the ground rotation induced by the Mw=9.0, 11th of March 2011, Japan earthquake. The rotation measurements have been conducted with a ring laser gyroscope operating in a vertical plane, thus detecting rotations around the horizontal axis. Comparison of ground rotations with vertical accelerations from a co-located force-balance accelerometer shows excellent ring laser coupling at periods longer than 100s. Under the plane wave assumption, we derive a theoretical relationship between horizontal rotation and vertical acceleration for Rayleigh waves. Due to the oblique mounting of the gyroscope with respect to the wave direction-of-arrival, apparent velocities derived from the acceleration / rotation rate ratio are expected to be always larger than, or equal to the true wave propagation velocity. This hypothesis is confirmed through comparison with fundamental-mode, Rayleigh wave phase velocities predicted for a standard Earth model.Comment: Accepted for publication in Journal of Seismolog