Quantum Signature of a Squeezed Mechanical Oscillator

Recent optomechanical experiments have observed nonclassical properties in macroscopic mechanical oscillators. A key indicator of such properties is the asymmetry in the strength of the motional sidebands produced in the probe electromagnetic field, which is originated by the noncommutativity between the oscillator ladder operators. Here we extend the analysis to a squeezed state of an oscillator embedded in an optical cavity, produced by the parametric effect originated by a suitable combination of optical fields. The motional sidebands assume a peculiar shape, related to the modified system dynamics, with asymmetric features revealing and quantifying the quantum component of the squeezed oscillator motion.

Right post-traumatic diaphragmatic hernia with liver and intestinal dislocation

Right diaphragmatic hernia is an uncommon injury following abdominal trauma. A case of delayed right post-traumatic diaphragmatic hernia is presented. The patient referred us with wheezing and cough since 1 month. A chest-abdominal computed tomography scan demonstrated a large diaphragmatic defect with liver and intestinal dislocation. The patient underwent surgical intervention with diaphragmatic repair. No complications were observed during admission and follow-up is actually negative for recurrence.

Black esophagus: acute esophageal necrosis, clinical case and review of literature

Black esophagus is a rare, multifactorial disease. A case of acute black esophagus following pancreatic resection is presented. The patient referred us with a specific gastrointestinal bleeding. An esophagogastroduodenoscopy confirmed the diagnosis. We performed conservative treatment with complete esophageal re-epithelization and negative follow-up for stenosis or necrosis relapse.

Dynamical Two-Mode Squeezing of Thermal Fluctuations in a Cavity Optomechanical System

We report the experimental observation of two-mode squeezing in the oscillation quadratures of a thermal micro-oscillator. This effect is obtained by parametric modulation of the optical spring in a cavity optomechanical system. In addition to stationary variance measurements, we describe the dynamic behavior in the regime of pulsed parametric excitation, showing an enhanced squeezing effect surpassing the stationary 3 dB limit. While the present experiment is in the classical regime, our technique can be exploited to produce entangled, macroscopic quantum optomechanical modes.

Impact of anatomical location of lower limb venous thrombus on the risk of subsequent cancer

After a proximal deep-vein thrombosis (P-DVT), the risk of diagnosis of a previously unsuspected cancer is high. Isolated distal DVT (iD-DVT; i.e. infra-popliteal DVT without pulmonary embolism [PE]) and isolated superficial-vein thrombosis (iSVT; i.e. without concomitant DVT and PE) are at least as frequent as P-DVT but their association with subsequent cancer is uncertain. We exploited data from the OPTIMEV prospective, observational, multicentre study to i) compare the risk of subsequent cancer three years after a first objectively confirmed iSVT, iD-DVT and iP-DVT in patients without a prior history of cancer or of venous thromboembolism, ii) assess predictors of subsequent cancer in cases of iD-DVT. The overall cumulative rates of cancer among the 304 patients with iSVT, 536 patients with iD-DVT, and 327 patients with iP-DVT were similar (3.4% 95% confidence interval [1.8-6.2], 3.9% [2.5-5.9] and 3.9% [2.3-6.8], respectively), regardless of whether the index venous thromboembolic event was unprovoked or associated with a major transient risk factor. Neither anatomical (muscular vs deep-calf DVT) nor ultrasound scan characteristics (number of thrombosed veins, clot diameter under compression) seemed strongly associated with the risk of cancer in cases of iD-DVT. In patients managed in routine practice, all the different clinical expressions of lower limb venous thromboembolism are associated with a similar risk of subsequent cancer. From a clinical practice point of view, this suggests that cancer screening, without discussing the necessity, or not, of such screening, should not differ between a deep-proximal, deep-distal or superficial location of thrombosis.

Squeezing a thermal mechanical oscillator by stabilized parametric effect on the optical spring

We report the confinement of an optomechanical micro-oscillator in a squeezed thermal state, obtained by parametric modulation of the optical spring. We propose and implement an experimental scheme based on parametric feedback control of the oscillator, which stabilizes the amplified quadrature while leaving the orthogonal one unaffected. This technique allows us to surpass the -3  dB limit in the noise reduction, associated with parametric resonance, with a best experimental result of -7.4  dB. While the present experiment is in the classical regime, in a moderately cooled system our technique may allow squeezing of a macroscopic mechanical oscillator below the zero-point motion.

Nonequilibrium steady-state fluctuations in actively cooled resonators

We analyze heat and work fluctuations in the gravitational wave detector AURIGA, modeled as a macroscopic electromechanical oscillator in contact with a thermostat and cooled by an active feedback system. The oscillator is driven to a steady state by the feedback cooling, equivalent to a viscous force. The experimentally measured fluctuations are in agreement with our theoretical analysis based on a stochastically driven Langevin system. The asymmetry of the fluctuations of the absorbed heat characterizes the oscillator's nonequilibrium steady state and reveals the extent to which a feedback cooled system departs from equilibrium in a statistical mechanics perspective.

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.

Loss budget of a setup for measuring mechanical dissipations of silicon wafers between 300 and 4 K

A setup for measuring mechanical losses of silicon wafers has been fully characterized from room temperature to 4 K in the frequency range between 300 Hz and 4 kHz: it consists of silicon wafers with nodal suspension and capacitive and optical vibration sensors. Major contributions to mechanical losses are investigated and compared with experimental data scanning the full temperature range; in particular, losses due to the thermoelastic effect and to the wafer clamp are modeled via finite element method analysis; surface losses and gas damping are also estimated. The reproducibility of the measurements of total losses is also discussed and the setup capabilities for measuring additive losses contributed by thin films deposited on the wafers or bonding layers. For instance, assuming that additive losses are due to an 80-nm-thick wafer bond layer with Young modulus about ten times smaller than that of silicon, we achieve a sensitivity to bond losses at the level of 5x10(-3) at 4 K and at about 2 kHz.

Upper limits on gravitational-wave emission in association with the 27 Dec 2004 giant flare of SGR1806-20

At the time when the giant flare of SGR1806-20 occurred, the AURIGA "bar" gravitational-wave (GW) detector was on the air with a noise performance close to stationary Gaussian. This allows us to set relevant upper limits, at a number of frequencies in the vicinities of 900 Hz, on the amplitude of the damped GW wave trains, which, according to current models, could have been emitted, due to the excitation of normal modes of the star associated with the peak in x-ray luminosity.

Trichites of Strombidium (Ciliophora, Oligotrichida) are extrusomes

The trichites of Strombidium and related genera have been considered either as a cytoskeletal armature or as extrusomes. To demonstrate their true nature, a study was undertaken on two marine Strombidium species by ultrastructural and cytochemical analysis as well as in vivo experiments. Trichites, extending from the cortex into the cell, are rod-shaped, membrane-bounded, and have a complex structure. The following elements of the trichites, are distinguishable: an electron-transparent lumen, a laminated layer, and a compact layer. In trichites of one species, thin "rings" surround the lumen. Numerous short, curved tubules with a polysaccharide wall are present in the cytoplasm surrounding the trichites. At the cortical end, each trichite is enveloped by a "cap" of electron-dense proteinaceous material. In some cases, the cortical alveoli appear interrupted, forming a "hole" for trichite ejection. Ejection of rod-shaped structures, up to 5 times longer than resting trichites, was obtained by in vivo treatments with dextran and aminoethyldextran. Negative staining indicated that these structures were transformed trichites. As no other possible extrusive structures were observed in the cytoplasm of Strombidium, trichites were considered extrusomes.

First search for gravitational wave bursts with a network of detectors

We report the initial results from a search for bursts of gravitational radiation by a network of five cryogenic resonant detectors during 1997 and 1998. This is the first significant search with more than two detectors observing simultaneously. No gravitational wave burst was detected. The false alarm rate was lower than 1 per 10(4) yr when three or more detectors were operating simultaneously. The typical threshold was H approximately 4x10(-21) Hz-1 on the Fourier component at approximately 10(3) Hz of the gravitational wave strain amplitude. New upper limits for amplitude and rate of gravitational wave bursts have been set.