The sensitivity of aLIGO detectors is adversely affected by the presence of noise caused by light scattering. Low frequency seismic disturbances can create higher frequency scattering noise adversely ...impacting the frequency band in which we detect gravitational waves. In this paper, we analyze instances of a type of scattered light noise we call "Fast Scatter" that is produced by motion at frequencies greater than 1 Hz, to locate surfaces in the detector that may be responsible for the noise. We model the phase noise to better understand the relationship between increases in seismic noise near the site and the resulting Fast Scatter observed. We find that mechanical damping of the Arm Cavity Baffles (ACBs) led to a significant reduction of this noise in recent data. For a similar degree of seismic motion in the 1-3 Hz range, the rate of noise transients is reduced by a factor of ~ 50.
Modern gravitational-wave observatories require robust low-frequency active seismic isolation in order to keep the interferometer at its ideal operating conditions. Seismometers are used to measure ...both the motion of the ground and isolated platform. These devices are susceptible to contamination from ground tilt at frequencies below 0.1 Hz, particularly arising from wind-pressure acting on building walls. Consequently, during LIGO's first observing run both observatories suffered significant downtime when wind-speeds were above 7 m/s. We describe the use of ground rotation sensors at the LIGO Hanford Observatory to correct nearby ground seismometers to produce tilt-free ground translation signals. The use of these signals for sensor correction control improved low-frequency seismic isolation and allowed the observatory to operate under wind speeds as high as \(15-20\) m/s.
Gravitational wave observatories have always been affected by tele-seismic earthquakes leading to a decrease in duty cycle and coincident observation time. In this analysis, we leverage the power of ...machine learning algorithms and archival seismic data to predict the ground motion and the state of the gravitational wave interferometer during the event of an earthquake. We demonstrate improvement from a factor of 5 to a factor of 2.5 in scatter of the error in the predicted ground velocity over a previous model fitting based approach. The level of accuracy achieved with this scheme makes it possible to switch control configuration during periods of excessive ground motion thus preventing the interferometer from losing lock. To further assess the accuracy and utility of our approach, we use IRIS seismic network data and obtain similar levels of agreement between the estimates and the measured amplitudes. The performance indicates that such an archival or prediction scheme can be extended beyond the realm of gravitational wave detector sites for hazard-based early warning alerts.
We present a tabletop six-axis vibration isolation system, compatible with Ultra-High Vacuum (UHV), which is actively damped and provides 25 dB of isolation at 10 Hz and 65 dB at 100 Hz. While this ...isolation platform has been primarily designed to support optics in the Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors, it is suitable for a variety of applications. The system has been engineered to facilitate the construction and assembly process, while minimizing cost. The platform provides passive isolation for six degrees of freedom using a combination of vertical springs and horizontal pendula. It is instrumented with voice-coil actuators and optical shadow sensors to damp the resonances. All materials are compatible with stringent vacuum requirements. Thanks to its architecture, the system's footprint can be adapted to meet spatial requirements, while maximizing the dimensions of the optical table. Three units are currently operating for LIGO. We present the design of the system, controls principle, and experimental results.
Parametric instabilities have long been studied as a potentially limiting effect in high-power interferometric gravitational wave detectors. Until now, however, these instabilities have never been ...observed in a kilometer-scale interferometer. In this work we describe the first observation of parametric instability in an Advanced LIGO detector, and the means by which it has been removed as a barrier to progress.
Anaesthetics are used daily in human and veterinary medicine as well as in scientific research. Anaesthetics have an impact on cell homeostasis especially through modulation of protein ...post-translational modifications. O-GlcNAcylation, a ubiquitous post-translational modification, plays a role in many biological processes. The aims of this study were to evaluate whether (1) anaesthesia influences O-GlcNAcylation and (2) its stimulation affects physiological parameters. Male Wistar rats (n = 38) were anaesthetized with ketamine-xylazine or isoflurane. They randomly received either an intravenous injection of Ringer's lactate or NButGT (10mg/kg) in order to increase O-GlcNAcylation levels. One hour after induction of anaesthesia, haemodynamic parameters and plasmatic markers were evaluated. Heart, brain and lungs were harvested and O-GlcNAcylation levels and O-GlcNAc-related enzymes were evaluated by western blot. Cardiac and pulmonary O-GlcNAcylation levels and cardiac, cerebral and pulmonary O-GlcNAc associated enzyme expression were not impacted with anaesthesia. Compared with ketamine-xylazine, isoflurane had a lower impact on blood pressure, heart rate and glycaemia. Pharmacological stimulation of O-GlcNAcylation by NButGT did not affect the physiological parameters. This study offers unprecedented insights into the regulation of O-GlcNAcylation and O-GlcNAc related enzymes during anaesthesia. Pharmacological stimulation of O-GlcNAcylation over a 1-h period did not disrupt the physiological balance in healthy anaesthetized rats.
Sepsis in the young population, which is particularly at risk, is rarely studied. O-GlcNAcylation is a post-translational modification involved in cell survival, stress response and metabolic ...regulation. O-GlcNAc stimulation is beneficial in adult septic rats. This modification is physiologically higher in the young rat, potentially limiting the therapeutic potential of O-GlcNAc stimulation in young septic rats. The aim is to evaluate whether O-GlcNAc stimulation can improve sepsis outcome in young rats. Endotoxemic challenge was induced in 28-day-old rats by lipopolysaccharide injection (E. Coli O111:B4, 20 mg·kg−1) and compared to control rats (NaCl 0.9%). One hour after lipopolysaccharide injection, rats were randomly assigned to no therapy, fluidotherapy (NaCl 0.9%, 10 mL·kg−1) ± NButGT (10 mg·kg−1) to increase O-GlcNAcylation levels. Physiological parameters and plasmatic markers were evaluated 2h later. Finally, untargeted mass spectrometry was performed to map cardiac O-GlcNAcylated proteins. Lipopolysaccharide injection induced shock with a decrease in mean arterial pressure and alteration of biological parameters (p < 0.05). NButGT, contrary to fluidotherapy, was associated with an improvement of arterial pressure (p < 0.05). ATP citrate lyase was identified among the O-GlcNAcylated proteins. In conclusion, O-GlcNAc stimulation improves outcomes in young septic rats. Interestingly, identified O-GlcNAcylated proteins are mainly involved in cellular metabolism.
Anesthesia is used on a daily basis in Human medicine and for scientific research. Among anesthetic agents, ketamine and isoflurane are the most commonly used for intravenous and inhalation-induced ...anesthesia, respectively. Still, such anesthetics does affect cell homeostasis through cell signaling pathways with modulations of protein post-translational modifications (PTMs). O-GlcNAcylation (O-GlcNAc) is a ubiquitous PTM involved in many biological processes. Hirose et al. reported that isoflurane could induce an increase in O-GlcNAc levels. However, this study was not designed to specifically evaluate this aspect. Considering that O-GlcNAc stimulation is cardioprotective in acute pathologies, the increase in O-GlcNAc levels induced by anesthesia could potentially have unexpected impact on research projects.
Our study aimed to evaluate whether (1) anesthesia influences O-GlcNAc and (2) O-GlcNAc stimulation affects physiological parameters in healthy rats.
General anesthesia was performed on adult healthy males Wistar rats with either ketamine-xylazine (KX) or isoflurane (ISO) for one hour. Rats were injected either with Ringer Lactate or NButGT (KX+N, ISO+N) treatment (10mg/kg) to increase O-GlcNAc levels. Upon sacrifice, hemodynamics parameters and plasmatic markers were evaluated, and heart was harvested. O-GlcNAc and O-GlcNAc-related enzymes levels were evaluated by western blot.
As expected, isoflurane had lower impact on hemodynamics parameters. Surprisingly, anesthesia (neither ISO nor KX) had no impact on O-GlcNAc levels in the heart (KX: 0.90±0.18; ISO: 0.87±0.04; P<0.05). Pharmacological stimulation of O-GlcNAc by NButGT efficiently increased O-GlcNAc levels in the heart (KX: 0.90±0.18; KX+N: 1.22±0.16; ISO: 0.87±0.04; ISO+N: 1.32±0.08; P<0.05) and had no impact on physiological parameters such as heart rate, mean blood pressure, blood gazes, electrolytes or pH.
These results prove that neither ketamine-xylazine nor isoflurane-induced anesthesia increase O-GlcNAc levels under standardized anesthetics conditions. Pharmacological stimulation of O-GlcNAc over a 1-hour period did not disrupt the physiological balance. We also confirm that on healthy rat, acute increase in O-GlcNAc levels does not impact cardiovascular parameters.
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