Experimental determination of molar polarizability of nitrogen by a multi-reflection inteferometric technique

A novel optical pressure standard, based on a multi-reflection interferometric technique, has been recently developed. It is based on the measurement of the refractive index of a gas through an unbalanced homodyne interferometer (UINT) and is able to measure pressure with a relative standard uncertainty of 10 ppm at 100 kPa [1]. In this work, the interferometer was used to measure the molar polarizability of nitrogen, which resulted in agreement with recent previous determinations, paving the way for using photonic pressure standards as accurate and fast transfer standards of the pascal

Quantitative analysis and processing of surfaces and profiles from profilometry images

Surface metrology is concerned with inspecting morphological parameters of a surfaces or profiles, by using contact or non-contact profilometers. The following abstract describes the development of a software in Python environment that implements various processing methods on images from optical and stylus profilometers. In particular, the program focusses on image pre-processing and determination of dimensional parameters for 2D areas and 1D profiles. It is worth mentioning that many open and closed source programs are already distributed, but they do not provide a sufficient automatization in the image processing, often requiring the user to repeat the same steps for each image to obtain the expected results. The program has been initially developed within the framework of the EMPIR 20IND07 TracOptic project for the processing of a batch of topographies on RS-M and RS-N linear step samples, in order to compensate for the lack of automation for the calculation of height parameters. The developed program is designed to be modular and scalable for expanding the processing capabilities

Realisation of an optical pressure standard by a multi-reflection interferometric technique

A novel realization of an optical pressure standard, alternative to Fabry-Perot cavity-based techniques, is presented. It is based on the measurement of the refractive index of a gas through an unbalanced homodyne interferometer, designed to have one of its two arms formed by a multi reflection double mirror assembly to establish an unbalance length larger than 6 m in a compact setup. The paper illustrates the most important steps concerning its realization: the estimate of the pressure-induced deformation of the interferometer, the temperature control at millikelvin level and the measurement in vacuum of the unbalance of the interferometer. The evaluation of the uncertainty of the realized optical pressure standard currently demonstrated to fulfill the main goal of having the ability to measure pressure with a relative uncertainty of 10 ppm at 100 kPa

High prevalence of patent foramen ovale in migraine with aura

In this study we evaluated the presence of patent foramen ovale (PFO) in a cohort of 25 consecutive patients suffering from migraine with aura (MA) during an attack presenting to the emergency ward of an Italian hospital. Patients underwent brain magnetic resonance imaging (MRI) with contrast medium, routine coagulation tests, contrast transcranial echocolour–coded sonography (c–TCCS) and transoesophageal echocardiography (TEE). Of the enrolled patients, 88.7% showed a PFO according to the c–TCCS test, whereas only in 72% TEE confirmed the presence of PFO. This discordance could be due to the fact that c–TCCS is more sensitive even with shunts with minimal capacity also located in the pulmonary vasculature. After surgical treatment of the PFO, MA disappeared within two months. Also, the treatment with warfarin as well as with acetylsalicylic acid and flunarizine was able to dramatically reduce the frequency of migraine attacks. These data indicate a higher prevalence of PFO in MA vs. normal population (OR=2.92) and could suggest that the presence of arteriovenous (AV) shunts could represent a trigger for MA attacks as well as for stroke, but more studies are needed to confirm this preliminary hypothesis

Quantum enhanced correlated interferometry for quantum gravity tests: the experimental set-up and the locking scheme

Abstract The search for Planck scale scale effect is one of holy grails of physics. In Fermilab a double Michelson interferometer was built for this purpose: the holometer. In this proceedings we review our effort to build a quantum enhanced holometer

Strichartz Estimates for the Vibrating Plate Equation

We study the dispersive properties of the linear vibrating plate (LVP) equation. Splitting it into two Schr\"odinger-type equations we show its close relation with the Schr\"odinger equation. Then, the homogeneous Sobolev spaces appear to be the natural setting to show Strichartz-type estimates for the LVP equation. By showing a Kato-Ponce inequality for homogeneous Sobolev spaces we prove the well-posedness of the Cauchy problem for the LVP equation with time-dependent potentials. Finally, we exhibit the sharpness of our results. This is achieved by finding a suitable solution for the stationary homogeneous vibrating plate equation.Comment: 18 pages, 4 figures, some misprints correcte

A low noise laser interferometry readout for challenging acceleration measurements in space

Acceleration measurements are needed to various levels of sensitivity for almost all space missions in the fields of fundamental physics, space geodesy, space exploration, as well as on the space station. Acceleration sensors have a "free" (or weakly coupled) test mass inside a cage rigid with the spacecraft, and yield their relative acceleration by reading the relative displacements (linear and angular, if needed) of the test mass with respect to the cage