Rotational sensitivity of the "G-Pisa" gyrolaser

G-Pisa is an experiment investigating the possibility to operate a high sensitivity laser gyroscope with area less than $1 \rm m^2$ for improving the performances of the mirrors suspensions of the gravitational wave antenna Virgo. The experimental set-up consists in a He-Ne ring laser with a 4 mirrors square cavity. The laser is pumped by an RF discharge where the RF oscillator includes the laser plasma in order to reach a better stability. The contrast of the Sagnac fringes is typically above 50% and a stable regime has been reached with the laser operating both single mode or multimode. The effect of hydrogen contamination on the laser was also checked. A low-frequency sensitivity, below $1 \rm Hz$, in the range of $10^{-8} \rm {(rad / s)/ \sqrt{Hz}}$ has been measured.Comment: 6 pages, 6 figures, presented at the EFTF-IFCS joint conference 200

A high sensitivity tool for geophysical applications: A geometrically locked Ring Laser Gyroscope

This work demonstrates that a middle size ring laser gyroscope (RLG) can be a very sensitive and robust instrument for rotational seismology, even if it operates in a quite noisy environment. The RLG has a square cavity, $1.60\times 1.60$ m$^2$, and it lies in a plane orthogonal to the Earth rotational axis. The Fabry-Perot optical cavities along the diagonals of the square were accessed and their lengths were locked to a reference laser. Through a quite simple locking circuit, we were able to keep the sensor fully operative for 14 days. The obtained long term stability is of the order of 3~nanorad/s and the short term sensitivity close is to 2~nanorad/s$\cdot$Hz$^{-1/2}$. These results are limited only by the noisy environment, our laboratory is located in a building downtown.Comment: 9 pages, 4 figures, 25 reference

Arthrobacter sp. Inoculation Improves Cactus Pear Growth, Quality of Fruits, and Nutraceutical Properties of Cladodes

A study was undertaken to determine the effects of a strain of Arthrobacter sp., a Plant Growth-Promoting Bacteria (PGPB), on plant phenology and qualitative composition of Opuntia ficus-indica (L.) Mill. fruits and cladodes. The strain was inoculated in soil, and its effects on cactus pear plants were detected and compared to nontreated plants. Compared to the latter, the treatment with bacteria promoted an earlier plant sprouting (2 months before the control) and fruitification, ameliorating fruit quality (i.e., improved fresh and dry weight: + 24% and + 26%, respectively, increased total solid content by 30% and polyphenols concentrations by 22%). The quality and quantity of monosaccharides of cladodes were also increased by Arthrobacter sp. with a positive effect on their nutraceutical value. In summer, the mean values of xylose, arabinose, and mannose were significantly higher in treated compared to not treated plants (+ 3.54; + 7.04; + 4.76 mg/kg d.w. respectively). A similar trend was observed in autumn, when the cladodes of inoculated plants had higher contents, i.e., 33% xylose, 65% arabinose, and 40% mannose, respect to the controls. In conclusion, Arthrobacter sp. plays a role in the improvement of nutritional and nutraceutical properties of cactus pear plants due to its capabilities to promote plant growth. Therefore, these results open new perspectives in PGPB application in the agro-farming system as alternative strategy to improve cactus pear growth, yield, and cladodes quality, being the latter the main by-product to be utilized for additional industrial uses

Geometrical scale-factor stabilization of square cavity ring laser gyroscopes

Large frame ring laser gyros performances are ultimately limited by the instabilities of their geometrical parameters. We present the experimental activity on the GP2 ring laser gyro. GP2 is a ring laser gyro devoted to develop advanced stabilization techniques of the ring cavity geometrical scale-factor. A method based on optical interferometry has been developed for canceling the deformations of the resonator. The method is based on the measurement and stabilization of the absolute length of the cavity perimeter and of the resonators formed by the opposite cavity mirrors. The optical frequency reference in the experiment is an iodine-stabilized He-Ne laser, with a relative frequency stability of 10-11. The measurement of the absolute length of the two resonators has been demonstrated up to now on a test bench. We discuss the experimental results on GP2: the present performances as a ring laser gyro and the stabilization scheme to be implemented in the near future

Length measurement and stabilization of the diagonals of a square area laser gyroscope

Large frame ring laser gyroscopes are top sensitivity inertial sensors able to measure absolute angular rotation rate below prad s-1 in few seconds. The GINGER project is aiming at directly measuring the Lense-Thirring effect with an 1% precision on an Earth based experiment. GINGER is based on an array of large frame ring laser gyroscopes. The mechanical design of this apparatus requires a micrometric precision in the construction and the geometry must be stabilized in order to keep constant the scale factor of the instrument. The proposed control is based on square cavities, and relies on the length stabilization of the two diagonals, which must be equal at micrometric level. GP2 is the prototype devoted to the scale factor control test. As a first step, the lengths of the diagonals of the ring cavity have been measured through an interferometric technique with a statistical accuracy of some tens of nanometers, and they have been locked to the wavelength of a reference optical standard. Continuous operation has been obtained over more than 12 h, without loss of sensitivity. GP2 is located in a laboratory with standard temperature stabilization, with residual fluctuations of the order of 1 C. Besides the demonstration of the control effectiveness, the analysis of the Sagnac frequency demonstrates that relative small and low-cost ring lasers (around one meter of side) can also achieve a sensitivity of the order of nrad s-1 in the range 0.01-10 Hz in a standard environment, which is the target sensitivity in many different applications, such as rotational seismology and next generation gravitational waves detectors

The GINGER Project and status of the ring-laser of LNGS

A ring-laser attached to the Earth measures the absolute angular velocity of the Earth summed to the relativistic precessions, de Sitter and Lense-Thirring. GINGER (Gyroscopes IN GEneral Relativity) is a project aiming at measuring the LenseThirring effect with a ground based detector; it is based on an array of ring-lasers. Comparing the Earth angular velocity measured by IERS and the measurement done with the GINGER array, the Lense-Thirring effect can be evaluated. Compared to the existing space experiments, GINGER provides a local measurement, not the averaged value and it is unnecessary to model the gravitational field. It is a proposal, but it is not far from being a reality. In fact the GrossRing G of the Geodesy Observatory of Wettzell has a sensitivity very close to the necessary one. G ofWettzell is part of the IERS system which provides the measure of the Length Of the DAY (LOD); G provides information on the fast component of LOD. In the last few years, a roadmap toward GINGER has been outlined. The experiment G-GranSasso, financed by the INFN Commission II, is developing instrumentations and tests along the roadmap of GINGER. In this short paper the main activities of G-GranSasso and some results will be presented. The first results of GINGERino will be reported, GINGERino is the large ring-laser installed inside LNGS and now in the commissioning phase. Ring-lasers provide as well important informations for geophysics, in particular the rotational seismology, which is an emerging field of science. GINGERino is one of the three experiments of common interest between INFN and INGV

Delving into the reducing effects of the GABAB positive allosteric modulator, KK-92A, on alcohol-related behaviors in rats

Recent studies have demonstrated the ability of the positive allosteric modulator (PAM) of the GABAB receptor (GABAB PAM), KK-92A, to suppress operant alcohol self-administration and reinstatement of alcohol seeking in selectively bred Sardinian alcohol-preferring (sP) rats. The present study was designed to scrutinize the suppressing effects of KK-92A on alcohol-related behaviors; to this end, four separate experiments were conducted to address just as many new research questions, some of which bear translational value. Experiment 1 found that 7-day treatment with KK-92A (0, 5, 10, and 20 mg/kg, intraperitoneally [i.p.]) effectively reduced alcohol intake in male sP rats exposed to the home-cage 2-bottle "alcohol (10% v/v) vs. water" choice regimen with 1 hour/day limited access, extending to excessive alcohol drinking the ability of KK-92A to suppress operant alcohol self-administration. Experiment 2 demonstrated that the ability of KK-92A to reduce lever-responding for alcohol was maintained also after acute, intragastric treatment (0, 20, and 40 mg/kg) in female sP rats trained to lever-respond for 15% (v/v) alcohol under the fixed ratio 5 schedule of reinforcement. In Experiment 3, acutely administered KK-92A (0, 5, 10, and 20 mg/kg, i.p.) dampened alcohol-seeking behavior in female sP rats exposed to a single session under the extinction responding schedule. Experiment 4 used a taste reactivity test to demonstrate that acute treatment with KK-92A (0 and 20 mg/kg, i.p.) did not alter either hedonic or aversive reactions to a 15% (v/v) alcohol solution in male sP rats, ruling out that KK-92A-induced reduction of alcohol drinking and self-administration could be due to alterations in alcohol palatability. Together, these results enhance the behavioral pharmacological profile of KK-92A and further strengthen the notion that GABAB PAMs may represent a novel class of ligands with therapeutic potential for treating alcohol use disorder