Dissipative and dispersive optomechanical couplings are experimentally observed in a photonic crystal split-beam nanocavity optimized for detecting nanoscale sources of torque. Dissipative coupling of up to approximately $500$ MHz/nm and dispersive coupling of $2$ GHz/nm enable measurements of sub-pg torsional and cantilever-like mechanical resonances with a thermally-limited torque detection sensitivity of 1.2$\times 10^{-20} \text{N} \, \text{m}/\sqrt{\text{Hz}}$ in ambient conditions and 1.3$\times 10^{-21} \text{N} \, \text{m}/\sqrt{\text{Hz}}$ in low vacuum. Interference between optomechanical coupling mechanisms is observed to enhance detection sensitivity and generate a mechanical-mode-dependent optomechanical wavelength response.Comment: 11 pages, 6 figure

Biopsy tissues were fixed in buffered formalin and processed routinely through paraffin wax, ensuring optimal orientation at the embedding stage. Sections (5 [t) were cut at six levels and stained with haematoxylin and eosin, periodic acid Schiff, and high iron diamine alcian blue (HIDAB), the latter with strict pH con-

IntroductionThe 2017 Joint Advisory Group on Gastrointestinal (GI) Endoscopy (JAG) census highlighted the pressure endoscopy services were under in meeting national targets and the factors behind this. In 2019, JAG conducted a further national census of endoscopy services to understand trends in activity, workforce and waiting time targets.MethodsIn April 2019, the census was sent to all eligible JAG-registered services. Collated data were analysed through various statistical methods. A further comparative dataset was created using available submissions from the 2017 census matched to services in the current census.ResultsThere was a 68% response rate (322/471). There has been a 12%–15% increase in activity across all GI procedures with largest increases in bowel cancer screening. Fewer services are meeting waiting time targets compared with 2017, with endoscopist, nursing and physical capacity cited as the main reasons. Services are striving to improve capacity: 80% of services have an agreed business plan to meet capacity and the number using insourcing has increased from 13% to 20%. The workforce has increased, with endoscopist numbers increasing by 15%, nurses and allied health professionals by 14% and clerical staff by 30%.ConclusionsThe 2019 JAG census is the most recent and extensive survey of UK endoscopy services. There is a clear trend of increasing activity with fewer services able to meet national waiting time targets than 2 years ago. Services have increased their workforce and improved planning to stem the tide but there remains a continued pressure to deliver high quality, safe endoscopy. In light of the COVID-19 pandemic, JAG recognises that these pressures will be severely exacerbated and waiting time targets for accreditation will need adjustment and tolerance during the evolution and recovery from the pandemic.

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SUMMARY Twenty‐three adult patients with a columnar lined (Barrett's) oesophagus are being treated with long‐term omeprazole, 40 mg daily. Twelve had never undergone anti‐reflux surgery (Group 1), the other eleven having previously had insertion of an Angelchik anti‐reflux prosthesis (Group 2). Endoscopy was carried out six months before, immediately before and six months, one year and two years into treatment. Multiple and standardized biopsies were taken at each endoscopy. Results from the two groups were similar. During the 6‐month run‐in period there was a statistically non‐significant increase in the linear extent of the columnar mucosa, but this showed a progressive, statistically significant decrease during the two years of treatment. Other evidence for regression of the Barrett's mucosa includes the emergence of large numbers of macroscopic squamous islands within the abnormal mucosa, an increase in the number of microscopic squamous islands, and microscopic squamous encroachment of the abnormal mucosa at the squamocolumnar junction. Histological assessment showed a reduction in the proportion of sulphomucin‐rich intestinal metaplasia, but this only achieved statistical significance in Group 1. The results substantiate the importance of acid in the pathogenesis of Barrett's oesophagus. Omeprazole may have a therapeutic role in bringing about regression of the metaplastic epithelium.

Hexagonal boron nitride (hBN) is an emerging layered material that plays a key role in a variety of two-dimensional devices, and has potential applications in nanophotonics and nanomechanics. Here, we demonstrate the first cavity optomechanical system incorporating hBN. Nanomechanical resonators consisting of hBN beams with average dimensions of 12 μm × 1.2 μm × 28 nm and minimum predicted thickness of 8 nm were fabricated using electron beam induced etching and positioned in the optical near-field of silicon microdisk cavities. Of the multiple devices studied here a maximum 0.16 pm/ sensitivity to the hBN nanobeam motion is demonstrated, allowing observation of thermally driven mechanical resonances with frequencies between 1 and 23 MHz, and largest mechanical quality factor of 1100 for a 23 MHz mode, at room temperature in high vacuum. In addition, the role of air damping is studied via pressure dependent measurements. Our results constitute an important step toward realizing integrated optomechanical circuits employing hBN.

We propose a scheme to realize optical quantum memories in an ensemble of nitrogen-vacancy centers in diamond that are coupled to a micro-cavity. The scheme is based on off-resonant Raman coupling, which allows one to circumvent optical inhomogeneous broadening and store optical photons in the electronic spin coherence. This approach promises a storage time of order one second and a time-bandwidth product of order 10 7 . We include all possible optical transitions in a 9-level configuration, numerically evaluate the efficiencies and discuss the requirements for achieving high efficiency and fidelity. PACS numbers:Quantum memories for optical photons [1][2][3] are essential elements for photonic quantum information processing. Long-distance quantum communication based on quantum repeaters [4,5] requires optical quantum memories. They can also be used in conjunction with probabilistic photon pair sources in order to realize deterministic single-photon sources [6], which are necessary for linear optical quantum computation [7]. The currently leading physical realizations of quantum memories include vapor cells, rare-earth ion doped crystals and cold atoms [8][9][10][11][12], where the use of ensembles [13] facilitates efficient coupling to photons. However, because of the physical dimensions or complexity of the trapping mechanism, these implementations do not seem to be well suited for miniaturization, which will be required for integrated on-chip photonic quantum information processing architectures [14].Negatively charged nitrogen-vacancy (NV − ) centers in diamond are attractive systems for implementing micronscale optical quantum memories. NV − centers demonstrate strong coupling to optical photons, which can be further enhanced via optical microcavities [15]. Entanglement between an optical photon and the electronic spin of a single NV − center [16], and between electronic spins of two distant NV − centers [17] have recently been demonstrated. Ground state electronic spin coherence times of 0.6 s have been shown using dynamical decoupling [18]. The electronic spin coherence in NV − ensembles has been used for storage and retrieval of microwave photons, see [19]. However, storing quantum states of optical photons remains challenging. In contrast to rareearth ion doped crystals [8,20], NV − centers exhibit a relatively short excited state lifetime, which prevents long-lived storage based on optical coherences. Electromagnetically induced transparency (EIT), which is based on application of a resonant control beam in a Λ-level configuration, has been implemented [21,22]. This could be an approach to use the ground state spin coherence to store optical photons. However, optical inhomogeneous broadening and interference due to closely-spaced excited states make it difficult to achieve high EIT contrasts [22], and the resulting loss prevents quantum storage of optical photons.In this letter, we propose to use an off-resonant Raman coupling approach [9,23] that allows one to circumvent the excited state inhomogeneou...

This study demonstrated that NNFs grown in culture under increased pressures undergo a transformation not seen in cells grown at atmospheric pressure. Cells grown under pressure demonstrated reduced growth rates, increased fibronectin production, and abnormal morphologies similar to fibroblasts isolated from venous ulcers. This study suggests that pressure elevations (like venous hypertension) can directly result in altered cell function and morphology that may contribute to the delayed wound healing seen in patients with venous ulcers. This model uses a pressurized incubator that may prove to be a valuable adjunct in studying the effects of venous hypertension.