Long-lived and Efficient Optomechanical Memory for Light.

We demonstrate a memory for light based on optomechanically induced transparency. We achieve a long storage time by leveraging the ultralow dissipation of a soft-clamped mechanical membrane resonator, which oscillates at MHz frequencies. At room temperature, we demonstrate a lifetime T_{1}≈23 ms and a retrieval efficiency η≈40% for classical coherent pulses. We anticipate the storage of quantum light to be possible at moderate cryogenic conditions (T≈10 K). Such systems could find applications in emerging quantum networks, where they can serve as long-lived optical quantum memories by storing optical information in a phononic mode.

Measuring the knot of non-Hermitian degeneracies and non-commuting braids.

Any system of coupled oscillators may be characterized by its spectrum of resonance frequencies (or eigenfrequencies), which can be tuned by varying the system's parameters. The relationship between control parameters and the eigenfrequency spectrum is central to a range of applications1-3. However, fundamental aspects of this relationship remain poorly understood. For example, if the controls are varied along a path that returns to its starting point (that is, around a 'loop'), the system's spectrum must return to itself. In systems that are Hermitian (that is, lossless and reciprocal), this process is trivial and each resonance frequency returns to its original value. However, in non-Hermitian systems, where the eigenfrequencies are complex, the spectrum may return to itself in a topologically non-trivial manner, a phenomenon known as spectral flow. The spectral flow is determined by how the control loop encircles degeneracies, and this relationship is well understood for [Formula: see text] (where [Formula: see text] is the number of oscillators in the system)4,5. Here we extend this description to arbitrary [Formula: see text]. We show that control loops generically produce braids of eigenfrequencies, and for [Formula: see text] these braids form a non-Abelian group that reflects the non-trivial geometry of the space of degeneracies. We demonstrate these features experimentally for [Formula: see text] using a cavity optomechanical system.

Normal-Mode Splitting in a Weakly Coupled Optomechanical System.

Normal-mode splitting is the most evident signature of strong coupling between two interacting subsystems. It occurs when two subsystems exchange energy between themselves faster than they dissipate it to the environment. Here we experimentally show that a weakly coupled optomechanical system at room temperature can manifest normal-mode splitting when the pump field fluctuations are antisquashed by a phase-sensitive feedback loop operating close to its instability threshold. Under these conditions the optical cavity exhibits an effectively reduced decay rate, so that the system is effectively promoted to the strong coupling regime.

Enhancing Sideband Cooling by Feedback-Controlled Light.

We realize a phase-sensitive closed-loop control scheme to engineer the fluctuations of the pump field which drives an optomechanical system and show that the corresponding cooling dynamics can be significantly improved. In particular, operating in the counterintuitive "antisquashing" regime of positive feedback and increased field fluctuations, sideband cooling of a nanomechanical membrane within an optical cavity can be improved by 7.5 dB with respect to the case without feedback. Close to the quantum regime of reduced thermal noise, such feedback-controlled light would allow going well below the quantum backaction cooling limit.

Mucocutaneous blood contact: blood release behavior of safety peripheral intravenous catheters.

BACKGROUND: Protection against needlestick injuries has significantly improved in recent years thanks to so-called "safety devices." However, a potential drawback occasionally reported by users is a risk of blood splashing. If this blood comes in contact with the mucous membranes, it could lead to an infection. METHODS: Five safety peripheral intravenous catheter brands were examined in a laboratory test. To simulate the extreme situations, which may arise through human use, the introducer needle was withdrawn from the catheter at 2 different angles whereby an industrial robot was used to simulate the sequence of this movement. Each brand was tested 30 times. The experiment was carried out using radioactively labeled human whole blood. The measurements for the transmitted volume of blood was taken both from an artificial head and from a surface measuring 18.5 cm by 26.5 cm at a height of 30 cm above the catheter; scintigraphy was used to take the measurements. RESULTS: The volume of blood droplets potentially splashing into the mucous membranes was in the range of 1 nL. CONCLUSION: For normal virus concentrations in the blood of sick patients, this dose is too small to cause hepatitis C and HIV.

Insulin leakage value in relation to pen needle length and administered dose after subcutaneous injection.

OBJECTIVE: During a subcutaneous injection with commonly used pen needles, the safety of drug administration plays an essential role. Today short needles with a length of 5.0 mm are increasingly being used. However, so far it is unresolved whether short needles of <5.0 mm affect the safety of insulin injections because of an increased backflow to the skin surface. We examined the influence of needle length and administered insulin dosage on the insulin backflow and the distribution of human insulin in the tissue by a quantitative determination of the amount of backflow of insulin to the skin surface. For the first time a new 4.5-mm pen needle was examined for its administration safety. RESEARCH DESIGN: Human insulin was radioactively marked. By means of an insulin pen different insulin dosages with pen needles of different lengths into fresh pork rind (ex vivo model) were administered. The amount of the marked insulin leaking from the tissues at the injection site was covered and absorbed immediately into a cotton swab. The amount of leakage was calculated by means of the radioactivity taken up by the swab. RESULTS: The amount of leakage for each measurement was less than 1% of the total dosage administered. The amount of leakage increased with increased dosage administered in absolute terms, but expressed as a percentage of the increased dosage administered the leakage decreased. CONCLUSION: The needle length (between 12 mm and 4.5 mm) did not have a meaningful influence on the amount of leakage; however, significant differences with different needle lengths could be observed.

Comparison of 4 different types of surgical gloves used for preventing blood contact.

BACKGROUND: Needlestick injuries are always associated with a risk of infection, because these types of punctures may expose healthcare workers to a patient's blood and/or body fluids. OBJECTIVE: To compare the efficacy of 4 different types of surgical gloves for preventing exposure to blood as a result of needlestick injury. METHODS: For simulation of needlestick injury, a circular sample of pork skin was tightened onto a bracket, and a single finger from a medical glove was stretched over the sample. First, a powder-free surgical glove with a gel coating was used to test blood contact. Second, a glove with a patented puncture indication system was used to test blood contact with a double-gloved hand. Third, 2 powder-free latex medical gloves of the same size and hand were combined for double gloving, again to test blood contact. Finally, we tested a glove with an integrated disinfectant on the inside. The punctures were carried out using diverse sharp surgical devices that were contaminated with (99)Tc-marked blood. The amount of blood contact was determined from the transmitted radioactivity. RESULTS: For the powder-free surgical glove with a gel coating, a mean volume of 0.048 microL of blood (standard error of the mean [SEM], 0.077 microL) was transferred in punctures with an automated lancet at a depth of 2.4 mm through 1 layer of latex. For the glove with an integrated disinfectant on the inside, the mean volume of blood transferred was 0.030 microL (SEM, 0.0056 microL) with a single glove and was 0.024 microL (SEM, 0.003 microL) with 2 gloves. For the glove with the patented puncture indication system, a mean volume of 0.024 microL (SEM, 0.003 microL) of blood was transferred. CONCLUSIONS: Double gloving or the use of a glove with disinfectant can result in a decrease in the volume of blood transferred. Therefore, the use of either of these gloving systems could help to minimize the risk of bloodborne infections for medical staff.

Study of blood contact in simulated surgical needlestick injuries with single or double latex gloving.

OBJECTIVE: Needlestick injuries are the most common injuries that occur among operation room personnel in the health care service. The risk of infection after a needlestick injury during surgery greatly depends on the quantity of pathogenic germs transferred at the point of injury. The aim of this study was to measure the quantity of blood transferred at the point of a percutaneous injury by using radioactively labeled blood. DESIGN: This study was conducted to evaluate the risk of infection through blood contact by simulating surgical needlestick injuries ex vivo. The tests were conducted by puncturing single and double latex gloves with diverse sharp devices and objects that were contaminated with Technetium solution-labeled blood. RESULTS: A mean volume of 0.064 microL of blood was transferred in punctures with the an automatic lancet at a depth of 2.4 mm through 1 layer of latex. When the double-gloving indicator technique was used, a mean volume of only 0.011 microL of blood was transferred (median, 0.007 microL); thus, by wearing 2 pairs of gloves, the transferred volume of blood was reduced by a factor of 5.8. CONCLUSIONS: The results revealed that double gloving leads to a significant reduction in the quantity of blood transferred during needlestick injury.

Glove perforation in outpatient dermatologic surgery.

BACKGROUND: Intact surgical gloves ensure protection of health-care employees and health-care recipients. Nevertheless, glove perforation is very common and puncture rates above 50% have been published in the literature. OBJECTIVE: It was our aim to evaluate the perforation rate of surgical gloves in outpatient dermatologic surgery. METHODS: Six-hundred and sixty latex surgical gloves used in outpatient dermatologic surgery were evaluated for perforations using the approved water-leak method. Perforations were analyzed microscopically. RESULTS: Twenty of the 660 gloves were found to have perforations, which corresponds to a perforation rate of 3.0%. Only 5 of these perforations (25%) were noticed by the wearer. Perforations were more numerous in nondominant-handed gloves. Microscopically, all perforations could be identified as needle stick injuries. CONCLUSION: The risk of glove perforation in outpatient dermatologic surgery is lower than in many other medical specialties. The relatively high number of surgical procedures performed successively in outpatient dermatologic surgery, however, emphasizes the decisive relevance of an intact barrier between surgeon and patient. In view of the major fact that most perforations go unnoticed by the wearer, dermatologic surgeons must balance the improved safety of double gloving with costs and the loss of sensitivity and dexterity.