Analysis of Twitter conversations in obstetric anesthesiology using the hashtag #OBAnes during the onset of the COVID-19 pandemic.

BACKGROUND: #OBAnes is the most used hashtag in obstetric anesthesiology. The primary objective of the study was to characterize #OBAnes tweets at the onset of the COVID-19 pandemic. METHODS: Observational study of all tweets using #OBAnes between June 30, 2019 and October 19, 2020. A list of 19 topics was compiled to categorize each tweet. All Twitter users were manually assigned into one of 19 Symplur Healthcare Stakeholder categories. RESULTS: There were 12 431 tweets with #OBAnes during the study period, posted by 1704 unique users. The top user category was Doctor (n = 1211, 71%) with 9665 (78%) tweets. The top three topics identified within Twitter conversations were neuraxial anesthesia, COVID-19, and general anesthesia. CONCLUSIONS: Twitter facilitated thousands of obstetric anesthesia-related discussions during the onset of the COVID-19 pandemic, with most conversations centering on anesthesia type (neuraxial or general anesthesia).

Gated Conditional Displacement Readout of Superconducting Qubits.

We have realized a new interaction between superconducting qubits and a readout cavity that results in the displacement of a coherent state in the cavity, conditioned on the state of the qubit. This conditional state, when it reaches the cavity-following, phase-sensitive amplifier, matches its measured observable, namely, the in phase quadrature. In a setup where several qubits are coupled to the same readout resonator, we show it is possible to measure the state of a target qubit with minimal dephasing of the other qubits. Our results suggest novel directions for faster readout of superconducting qubits and implementations of bosonic quantum error-correcting codes.

Quantum engineering. Confining the state of light to a quantum manifold by engineered two-photon loss.

Physical systems usually exhibit quantum behavior, such as superpositions and entanglement, only when they are sufficiently decoupled from a lossy environment. Paradoxically, a specially engineered interaction with the environment can become a resource for the generation and protection of quantum states. This notion can be generalized to the confinement of a system into a manifold of quantum states, consisting of all coherent superpositions of multiple stable steady states. We have confined the state of a superconducting resonator to the quantum manifold spanned by two coherent states of opposite phases and have observed a Schrödinger cat state spontaneously squeeze out of vacuum before decaying into a classical mixture. This experiment points toward robustly encoding quantum information in multidimensional steady-state manifolds.

Bilayer graphene. Electron-hole asymmetric integer and fractional quantum Hall effect in bilayer graphene.

The nature of fractional quantum Hall (FQH) states is determined by the interplay between the Coulomb interaction and the symmetries of the system. The distinct combination of spin, valley, and orbital degeneracies in bilayer graphene is predicted to produce an unusual and tunable sequence of FQH states. Here, we present local electronic compressibility measurements of the FQH effect in the lowest Landau level of bilayer graphene. We observe incompressible FQH states at filling factors ν = 2p + 2/3, with hints of additional states appearing at ν = 2p + 3/5, where p = -2, -1, 0, and 1. This sequence breaks particle-hole symmetry and obeys a ν → ν + 2 symmetry, which highlights the importance of the orbital degeneracy for many-body states in bilayer graphene.

The genetic composition of populations of cynomolgus macaques (Macaca fascicularis) used in biomedical research.

BACKGROUND: The genetic composition of cynomolgus macaques used in biomedical research is not as well-characterized as that of rhesus macaques. METHODS: Populations of cynomolgus macaques from Sumatra, Corregidor, Mauritius, Singapore, Cambodia, and Zamboanga were analyzed using 24 STRs. RESULTS: The Sumatran and Cambodian populations exhibited the highest allelic diversity, while the Mauritian population exhibited the lowest. Sumatran cynomolgus macaques were the most genetically similar to all others, consistent with an Indonesian origin of the species. The high diversity among Cambodian animals may result from interbreeding with rhesus macaques. The Philippine and Mauritian samples were the most divergent from other populations, the former due to separation from the Sunda Shelf by deepwater and the latter due to anthropogenic translocation and extreme founder effects. CONCLUSIONS: Investigators should verify their research subjects' origin, ancestry, and pedigree to minimize risks to biomedical experimentation from genetic variance stemming from close kinship and mixed ancestry as these can obscure treatment effects.

Coulomb oscillations in antidots in the integer and fractional quantum Hall regimes.

We report measurements of resistance oscillations in micron-scale antidots in both the integer and fractional quantum Hall regimes. In the integer regime, we conclude that oscillations are of the Coulomb type from the scaling of magnetic field period with the number of edges bound to the antidot. Based on both gate-voltage and field periods, we find at filling factor ν = 2 a tunneling charge of e and two charged edges. Generalizing this picture to the fractional regime, we find (again, based on field and gate-voltage periods) at ν = 2/3 a tunneling charge of (2/3)e and a single charged edge.

Dynamic nuclear polarization in the fractional quantum Hall regime.

We investigate dynamic nuclear polarization in quantum point contacts (QPCs) in the integer and fractional quantum Hall regimes. Following the application of a dc bias, fractional plateaus in the QPC shift symmetrically about half filling of the lowest Landau level, ν=1/2, suggesting an interpretation in terms of composite fermions. Polarizing and detecting at different filling factors indicates that Zeeman energy is reduced by the induced nuclear polarization. Mapping effects from integer to fractional regimes extends the composite fermion picture to include hyperfine coupling.

Development of a Chinese-Indian hybrid (Chindian) rhesus macaque colony at the California National Primate Research Center by introgression.

BACKGROUND: Fullbred Chinese and Indian rhesus macaques represent genetically distinct populations. The California National Primate Research Center introduced Chinese founders into its Indian-derived rhesus colony in response to the 1978 Indian embargo on exportation of animals for research and the concern that loss of genetic variation in the closed colony would hamper research efforts. The resulting hybrid rhesus now number well over a thousand animals and represent a growing proportion of the animals in the colony. METHODS: We characterized the population genetic structure of the hybrid colony and compared it with that of their pure Indian and Chinese progenitors. RESULTS: The hybrid population contains higher genetic diversity and linkage disequilibrium than their full Indian progenitors and represents a resource with unique research applications. CONCLUSIONS: The genetic diversity of the hybrids indicates that the strategy to introduce novel genes into the colony by hybridizing Chinese founders and their hybrid offspring with Indian-derived animals was successful.

Operative treatment of hip fracture in haemodialysed patients.

PURPOSE: To study operative treatment and postoperative clinical outcomes of hip fracture in haemodialysed patients. METHODS: In 12 patients (8 men and 4 women) undergoing haemodialysis, 14 hip fractures were treated. Of these, 8 hips were treated with bipolar hip arthroplasty, one hip with total hip arthroplasty, 4 hips with a compression hip screw, and one hip with a gamma nail. The mean duration of dialysis treatment until fracture was 7 years. During a mean postoperative follow-up period of 17 months (range, 1-44 months), the patients' renal condition, type of fracture, and level of activities of daily living before and after surgery were assessed. RESULTS: Of the 7 patients who died during a mean follow-up period of 17 months, 2 died from myocardial infarction, 2 from sepsis, and one each from gastric cancer, pulmonary oedema, and liver failure. Five of the 8 patients with diabetic nephropathy died, whereas 6 of the 8 patients who underwent bipolar hip arthroplasty or total hip arthroplasty died. Most of the patients had declined level of activities of daily living postoperatively. CONCLUSION: For haemodialysed patients with fractures, it is essential to select the most suitable operating method and to conduct vigilant management before and after the operation.

Characterization of a density-corrected ultrasonic pneumotachometer for horses.

A density-corrected ultrasonic pneumotachometer designed specifically for horses (UF202) was evaluated and characterized with the aid of a custom-built apparatus. UF202 provided voltage outputs for airflow through and gas density within the flowhead. Baseline stability for flow channel output (VUF202) was < 0.35% full scale (FS), and VUF202 was linear over a range of +/- 50 l/s (R2 > or = 0.9976). Under optimal conditions, VUF202 accuracy was determined to be +/- 1.00% FS and repeatability was +/- 0.78% FS. VUF202 resolution was 24 ml/s. The rise time for VUF202 was 18 ms, and the -3-dB point was 18 Hz; digital compensation provided a flat frequency response to 32 Hz. VUF202 gain appeared to be stable over a period of 8 days. Density channel output (PUF202) was linear over a range of 1.11-1.23 g/l (R2 > or = 0.9645). PUF202 accuracy was calculated to be +/- 0.50% FS, and PUF202 repeatability was determined to be +/- 0.30% FS. Resistance of the flowhead was determined to be 0.013 cmH2O.l-1.s at a flow of 40 l/s. On the basis of this study, we conclude that UF202 should facilitate accurate measurement of breath-by-breath airflow of exercising horses.

High-performance liquid chromatography of phospholipids using deuterated solvents for infrared detection.

Infrared detection of chromatographic effluents offers the advantage of direct on-line quantitation of lipid fractions. However, infrared detection imposes limitations on the solvent systems that can be used for chromatography. Methanol and water, which are essential ingredients in the mobile phase for the successful chromatography of phospholipids, do not have spectral transmittance windows in the infrared region. Substituting deuterated methanol and deuterium oxide for methanol and water allowed infrared detection because they had lower infrared absorbance than their hydrogenated counterparts. We report a method that is suitable for the quantitative analysis of phosphatidylethanolamine, phosphatidylcholine and sphingomyelin in the tissue extracts. The lipid separation was accomplished on a micropraticulate silica gel column. Phosphatidylethanolamine and phosphatidylcholine were eluted isocratically with chloroform-acetonitrile-methanol-deuterium oxide (136:25:34:5.9) and detected at a wavelength of 5.75 microns. For the analysis of sphingomyelin, chloroform-acetonitrile-deuterated methanol-deuterium oxide (130:24:37.6:7.0) was used as the mobile phase, and the detection was at a wavelength of 6.15 microns.

A pulsed phase measurement ultrasonic flowmeter for medical gases.

Pneumotachometers are used to measure instantaneous flowrate in the respiratory gas streams. The presently available devices suffer from lack of linearity, slow response times, and gas density sensitivity. A new design of an ultrasonic gas flowmeter is presented in this paper: We investigate the acoustic characteristics of ring and piston shaped transducers, and describe a sampling method to avoid the error due to reflection. A microcomputer is used to overcome the 360 degrees detection ambiguity problem associated with phase detection technique. This design has been tested in clinical settings and has been shown to give linear response, independent of gas density, and to have a wide dynamic range.

Ascorbate and glutathione levels in the developing normal and dystrophic rat retina: effect of intense light exposure.

Ascorbic acid and glutathione were measured in retinas excised from normal rats reared in a cyclic light or dark environment and in dystrophic rats from the dark environment. Similar measurements were made on retinas from age matched rats exposed to intense visible light for periods of up to 24 hours. In other rats, ascorbic acid was given for various periods before exposure to intense light and the degree of photoreceptor cell death determined subsequently by rhodopsin measurements. In non-intense light treated rats ascorbate and glutathione were 12.1 nmol/retina at 20 days of age and 13.3 - 15.9 nmol/retina in 60 day old animals. In dystrophic rat retinas glutathione was 4-8% higher and ascorbate 10-20% higher than in normal dark reared rats. Although the levels of ascorbate and glutathione per retina increased during development, the molar ratios of the antioxidant materials to rhodopsin decreased by 36% and 60% in normal and dystrophic rats respectively. The levels of glutathione in young cyclic light or dark reared normals were unaffected by intense light exposure of either short (2-4 hrs) or long (24 hrs) duration. However, in both 20 and 40 day old dystrophic rats, intense light exposure resulted in a significant increase in retinal glutathione. In contrast to glutathione, retinal ascorbate decreased in normal rats exposed to intense light for 24 hrs, in an age and prior light environment dependent fashion. At ages greater than 20 days, normal rats exposed to light had significantly lower retinal ascorbate levels than their non-light exposed counterparts. The levels of ascorbate in 21-40 and 41-60 day old dark reared rat retinas were also significantly lower than in comparable intense light treated-cyclic light reared rats. In the youngest dystrophic rats whole eye ascorbate (retina, RPE, choroid and sclera) was 20-30% lower than in non-light treated rats, but in older mutant rats (41-60 day) light had no effect on the level of ascorbate in the retina. As determined by the level of rhodopsin remaining in the eye two weeks after 24 hrs light exposure, cyclic light reared rats lost 50-55% of their visual cells. However, cyclic light rats supplemented with ascorbic acid before intense light exposure lost only 30-35% of their visual cells.

Quantitative analysis of aminophospholipids by high-performance liquid chromatography using succinimidyl 2-naphthoxyacetate as a fluorescent label.

A simple and rapid high-performance liquid chromatographic procedure for the quantitative analysis of ethanolamine- and serine-containing phospholipids in tissue is described. The technique involves reaction of lipid extracts with succinimidyl 2-naphthoxyacetate to give fluorescent derivatives of aminophospholipids. Reaction products are separated by a silica gel column with gradient elution. The eluate is monitored by fluorescence detection at 228 nm (excitation) and 342 nm (emission). Ethanolamine and serine plasmalogens can be measured indirectly by converting their derivatives into lysophosphatidylethanolamine and lysophosphatidylserine derivatives with exposure to hydrogen chloride fumes. The method is highly sensitive and selective.

High-performance liquid chromatography of methylated phospholipids.

A rapid high-performance liquid chromatographic method for the separation of methylated phospholipids is described. The separation is accomplished on an amine column using acetonitrile--methanol--water as the eluting solvent and UV detection at 203 nm. The choice between gradient and isocratic elution for the separation depends upon the condition of column. The method is suitable for the isolation of phosphatidylcholine, sphingomyelin, lysophosphatidylcholine, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidyldimethylethanolamine and lysophosphatidylethanolamine from tissues. It is applicable to the study of reaction products in phosphatide methyltransferase assay mixtures. Choline and ethanolamine plasmalogens can be determined indirectly by converting them into lysophosphatidylcholine and lysophosphatidylethanolamine with exposure to hydrochloric acid fumes.

Improved procedure for the separation of phospholipids by high-performance liquid chromatography.

We describe a rapid and efficient high-performance liquid chromatography procedure for the separation of phospholipids. The separation is accomplished on a microparticulate silica gel column using isocratic elution and UV detection at 203 nm. The solvent mixture is acetonitrile--methanol--85% phosphoric acid(130:5:1.5, v/v). Complete separation is achieved within 30 min of phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine, phosphatidyldimethylethanolamine, lysophosphatidylethanolamine, phosphatidylcholine, lysophosphatidylcholine and sphingomyelin. The method is suitable for the analysis of phospholipids in tissue extracts.

Measurement of ethanolamine- and serine-containing phospholipids by high-performance liquid chromatography with fluorescence detection of their Dns derivatives.

We describe a liquid chromatographic procedure for the analysis of amino group-containing phosphoglycerides in tissue. The total lipid extract is derivatized with Dns-chloride at 50 degrees C for 3 h. Dns derivatives of phosphatidylethanolamine, lysophosphatidylethanolamine, phosphatidylserine and lysophosphatidylserine are separated by a silica gel column with gradient elution. The eluate is monitored by fluorescence detection at 342 nm (excitation) and 500 nm (emission). Ethanolamine and serine plasmalogens can be determined indirectly by converting their derivatives into Dns-lysophosphatidylethanolamine and Dns-lysophosphatidylserine with exposure to HCl fumes. The optimal sample size for derivative formation and analysis by this method is between 1 and 10 nmol of phospholipids (30 and 300 ng of lipid phosphorus), although the lower limit of detection is about 20 pmol. By analyzing the total lipid extract of rat brain we showed that the method was applicable to the quantitative analysis of amino group-containing phosphoglycerides in tissue samples.