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With a highly coherent, optically addressable electron spin, the nitrogen-vacancy (NV) center in diamond is a promising candidate for a node in a quantum network. A resonant microcavity can boost the flux of coherent photons emerging from single NV centers. Here, we present an open Fabry–Pérot microcavity geometry containing a single-crystal diamond membrane, which operates in a regime where the vacuum electric field is strongly confined to the diamond membrane. There is a field anti-node at the diamond–air interface. Despite the presence of surface losses, a finesse of [Formula: see text] was observed. The quality ([Formula: see text]) factor for the lowest mode number is [Formula: see text]; the mode volume [Formula: see text] is estimated to be [Formula: see text], where [Formula: see text] is the free-space wavelength. We investigate the interplay between different loss mechanisms and the impact these loss channels have on the performance of the cavity. This analysis suggests that the surface waviness (roughness with a spatial frequency comparable to that of the microcavity mode) is the mechanism preventing the [Formula: see text] ratio from reaching even higher values. Finally, we apply the extracted cavity parameters to the NV center and calculate a predicted Purcell factor exceeding 150.

Tunable open-access Fabry–Perot microcavities are versatile and widely applied in different areas of photonics research. The open geometry of such cavities enables the flexible integration of thin dielectric membranes. Efficient coupling of solid-state emitters in various material systems has been demonstrated based on the combination of high quality factors and small mode volumes with a large-range in situ tunability of the optical resonance frequency. Here, we demonstrate that by incorporating a diamond micromembrane with a small thickness gradient, both the absolute frequency and the frequency difference between two resonator modes can be controlled precisely. Our platform allows both the mirror separation and, by lateral displacement, the diamond thickness to be tuned. These two independent tuning parameters enable the double-resonance enhancement of nonlinear optical processes with the capability of tuning the pump laser over a wide frequency range. As a proof of concept, we demonstrate a > T H z continuous tuning range of doubly resonant Raman scattering in diamond, a range limited only by the reflective stopband of the mirrors. Based on the experimentally determined quality factors exceeding 300,000, our theoretical analysis suggests that, with realistic improvements, a ∼ m W threshold for establishing Raman lasing is within reach. Our findings pave the way to the creation of a universal, low-power frequency shifter. The concept can be applied to enhance other nonlinear processes such as second harmonic generation or optical parametric oscillation across different material platforms.

In volcanic and hydrothermal systems, monitoring of mass and stress changes by continuous gravity field and ground motion records provides information for both volcanic hazard assessment and estimation of geothermal resources. We aim at a better understanding of volcanic and geothermal system processes by addressing mass changes in relation with external influences such as anthropogenic (reservoir exploitation) and natural forcing (local and regional earthquake activity, earth tides). Þeistareykir is a geothermal field located within the Northern Volcanic Zone (NVZ) of Iceland on the Mid-Atlantic Ridge. Geothermal power production started in autumn 2017. For the first time on a geothermal production field, we deployed a network of 4 continuously recording gravity meters (3 superconducting meter, iGrav and one spring gravity meter gPhone) in order to cover the spatial and the temporal changes of gravity and to detect small variations related to the geothermal power plant operation (e.g. extraction and injection). All gravity monitoring stations are equipped with additional instrumentation to measure parameters that may affect the gravity records (e.g. GNSS and hydrometeorological sensors). Additionally, we deployed a temporal seismic network consisting of 14 broadband stations to enhance the seismic activity monitoring of the permanent Icelandic network in this very active region of the NVZ. Results of this unique experiment contribute to determine reservoir properties and main structures and may also reveal details of active tectonic processes. Here, we present the instrumental setup at the site and first results of more than 24 months of continuous gravity and seismicity records.

Continuous gravity measurements at active volcanoes are mostly accomplished using spring gravimeters, that can be operated under harsh field conditions. Unfortunately, these instruments do not provide reliable continuous measurements over long time-scales, due to the instrumental drift and artifacts driven by ambient parameters.An alternative to spring devices for continuous measurements is given by superconducting gravimeters (SGs), that are free from instrumental effects and thus allow to track even small gravity changes over time-scales from minutes to years. Nevertheless, SGs cannot be deployed in close proximity to the active structures of tall volcanoes, since they need host facilities with main electricity and a large installation surface.The mini-array of three SGs that were installed on Etna between 2014 and 2016 makes the first network of SGs ever installed on an active volcano. Here we present results from these instruments and show that, even though they are installed at relatively unfavorable positions (in terms of distances from the summit active craters), SGs can detect volcano-related gravity changes that would otherwise remain hidden, thus providing unique insight into the bulk processes driving volcanic activity.

This study examines the hydrogen peroxide concentrations measured near four models of hydrogen peroxide sterilizers, from two manufacturers, monitored in seven hospitals across the U.S. and Canada over several years. The results showed that the majority of sterilizers do not emit hazardous levels of hydrogen peroxide and none of them exceeded the OSHA PEL of 1 ppm (8-hr time-weighted average (TWA)), however several of the sterilizers exceeded 3 ppm, the short-term exposure limit in two states: Washington and Hawaii. One hospital found brief concentrations of 25–40 ppm hydrogen peroxide from 4 hydrogen peroxide sterilizers each time they opened the sterilizer at the end of its cycle. Although not exceeding the OSHA PEL, these exposures are of concern since this concentration is roughly half the NIOSH IDLH of 75 ppm, and operators in a busy hospital environment may receive these exposures multiple times a day.

Acute upper gastrointestinal (GI) bleeding is a common medical emergency and associated with significant morbidly and mortality. The risk of bleeding from peptic ulceration and oesophagogastric varices can be reduced by appropriate primary and secondary preventative strategies. Helicobacter pylori eradication and risk stratification with appropriate gastroprotection strategies when used with antiplatelet drugs and nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in preventing peptic ulcer bleeding, whilst endoscopic screening and either nonselective beta blockade or endoscopic variceal ligation are effective at reducing the risk of variceal haemorrhage. For secondary prevention of variceal haemorrhage, the combination of beta blockade and endoscopic variceal ligation is more effective. Recent data on the possible interactions of aspirin and NSAIDs, clopidogrel and proton pump inhibitors (PPIs), and the increased risk of cardiovascular adverse events associated with all nonaspirin cyclo-oxygenase (COX) inhibitors have increased the complexity of choices for preventing peptic ulcer bleeding. Such choices should consider both the GI and cardiovascular risk profiles. In patients with a moderately increased risk of GI bleeding, a NSAID plus a PPI or a COX-2 selective agent alone appear equivalent but for those at highest risk of bleeding (especially those with previous ulcer or haemorrhage) the COX-2 inhibitor plus PPI combination is superior. However naproxen seems the safest NSAID for those at increased cardiovascular risk. Clopidogrel is associated with a significant risk of GI haemorrhage and the most recent data concerning the potential clinical interaction of clopidogrel and PPIs are reassuring. In clopidogrel-treated patients at highest risk of GI bleeding, some form of GI prevention is indicated.

The kinetics of oxidation of a series of iron(II) cyclidene complexes by tris(1,10-phenanthroline)cobalt(III) in methanol have been measured by stopped flow spectrophotometry. The reactions obey a first order rate law when the cobalt(III) complex is present in large excess. The corresponding second order rate constants fall in the range 5.0–130 × 105 M−1s−1 (25°C). A linear correlation between the logarithm of the rate constant and the iron(III)/(II) redox potential indicates that the reactions behave as simple outer-sphere electron transfer processes. The self-exchange rate constants for the iron cyclidene complexes have been estimated from the Marcus equation and found to vary between 0.7 × 107 M1s1 and 9 × 107 M1s1. The dependence of the self-exchange rate constant on ligand structure is discussed.

Chemical sterilization is necessary for temperature sensitive items that cannot be sterilized with steam. These chemical sterilants are by their nature hazardous; otherwise, they would not function well. Modern sterilizers and associated equipment are designed so that these chemicals can be used safely. Whether through mechanical failure, wear and tear, or user error, leaks do sometimes occur. The maximum chemical exposure is determined by OSHA permissible exposure limits, if available, and if not available, employers should use recognized standards. Employers have a duty to ensure safe work environment and take appropriate action to mitigate potential risks. Employers should therefore assess the hazards of the chemicals used, the potential modes for leakage, means for identifying leaks and the risk of exposure of employees. Ideally, work practices should be developed by healthcare facilities so that sterile processing employees know what to do in case of a chemical leak or spill, and how to safely use these chemicals to ensure their own, and patient safety.

The factors controlling the reversible dioxygen binding in lacunar cobalt(II) cyclidene complexes (Figure 1) have been examined. Extensive structural variations reveal that the dioxygen affinity can be controlled by both steric and electronic means. The dioxygen affinity decreases monotonically with the length of a polymethylene bridging group (R 1 , Figure 1) from octamethylene to tetramethylene; no binding occurs with the still shorter trimethylene bridge. From the analysis of a large array of experimental data, the effects ofthe R 2 and R 3 substituents on dioxygen affinity are found to be mainly electronic; for example, electron-withdrawing groups at the R 2 and R 3 positions decrease the affinity

Bugs within programs typically arise within well-known motifs, such as complex language features or misunderstood programming interfaces. Some software development tools often detect some of these situations, and some integrated development environments suggest automated fixes for some of the simple cases. However, it is usually difficult to hand-craft and integrate more complex bug-fixing into these environments. We present a language for specifying program transformations which is paired with a novel methodology for identifying and fixing bug patterns within Java source code. We propose a combination of source code and bytecode analyses: this allows for using the control flow in the bytecode to help identify the bugs while generating corrected source code. The specification language uses a combination of syntactic rewrite rules and dataflow analysis generated from temporal logic based conditions. We demonstrate the approach with a prototype implementation.

The reactivity of superoxide toward two iron(II) complexes, one with the pentadentate ligand N,N'-di-2-picolyl4,7-diaza-1-oxacyclononane) (DPC) and the other with the hexadentate ligand N,N',N''tripicolyl-1,4,7-triazacyclononane) (TPC), has been examined using a range of electrochemical, spectroelectrochemical, and spectroscopic techniques. Repetitive cyclic voltammograms of both complexes indicate the formation of electrically conductive polymers on the electrode surface at negative potentials under aerobic conditions

The cobalt(II) cyclidene complexes are known to bind dioxygen reversibly under ambient conditions; however, the lifetime of the dioxygen adduct is limited by autoxidation. This paper describes a study of the autoxidation reactions of the cobalt(II) cyclidenes in nonaqueous media. The kinetics of the autoxidation reaction of the cobalt(II) complex are dependent on the nature of the ligand substituents and dioxygen concentration and on the nature and concentration of added base. Mechanistic details have been explored through isotopic substitution of the ligand

This article describes an approach to program optimization based on transformations, where temporal logic is used to specify side conditions, and strategies are created which expand the repertoire of transformations and provide a suitable level of abstraction. We demonstrate the power of this approach by developing a set of optimizations using our transformation language and showing how the transformations can be converted into a form which makes it easier to apply them, while maintaining trust in the resulting optimizing steps. The approach is illustrated through a transformational case study where we apply several optimizations to a small program.

Central service professionals play a vital role in ensuring patient safety, and in doing so, are exposed to harsh chemicals and sterilants. Knowing the effects of such chemicals is important so that the proper measures can be taken to prevent personal harm or injury as much as possible. Through the use of personal protective equipment, worker training and firmly adhering to OSHA practices, employees can work safely in the central service environment; especially when used in conjuction with engineering controls and gas monitoring.

The synthesis, characterization and structure are described for new cobalt complexes, with a BF2 + bridged, bis(a-dioxime) ligand, based upon a sterically demanding framework derived from an anthracene Diels-Alder adduct. The ligand provides a deep cleft within which axial ligands and/or O2 can bind. The crystal structures of the bis- and mono(BF2 +) bridged complexes have space groups P21/c and P I, respectively, with unit cell dimensions a = 12.662(2) A, b = 16.430(3) A, c = 10.438(3) A, β = 103.51(2)°, a = 12.046(1)A, b = I7.596(3)A, c = 9.939(I)A, a = 105.15(1)°, β = 102.87(1)°, and γ = 78.13(1), respectively. For both complexes Z = 2 and the residuals R and R w were 0.070, 0.104, and 0.059, 0.075, respectively. ESR studies show that the cobalt(II) complexes have a strong tendency to bind two axial nitrogen bases, adopting a coordination number of six. The dioxygen affinity of the new cobalt(II) dioxygen carrier is limited by the competition between axial base binding and O2 binding. This ext...

The kinetics of O2 binding to a demonstrably vacant coordination site on a cobalt(II) ion are determined, revealing a radical-like character for the reaction, with a very low activation barrier (ca. 1–2 kcal mol–1) and large entropically controlled rate constants, whose values approach those for myoglobin and haemoglobin (up to 108 dm3 mol–1 s–1).

Summary. The superconducting gravimeter has been used to measure the influence of barometric pressure on gravity in the frequency range 0.1–10 cycles/day. These measurements show that the incoherent barometric fluctuations are the major cause of random fluctuations in local gravity and account for much of the ‘noise’ on our gravimeter records. A simple model has been constructed which adequately explains the response of gravity to the local pressure fluctuations. These measurements also show a response to the global atmospheric tides at S1 and S2 which is much larger than the response to local fluctuations. Although this behaviour is most likely due to the response of the world-wide oceans to the atmospheric tides, no theoretical model has yet been constructed.

Summary. The results of previous work by the authors is used to remove most of the effects of ocean and atmospheric loading from an 18-month Earth gravity-tide record. The remaining signal is examined for additional influence of ocean and atmosphere and for evidence of the frequency-dependence of the response of the solid earth. Variations in time of the measured tides are shown to result from the atmospheric tide at S2 and appear to result from variations in ocean tides at other frequencies. The frequency-dependence of the solid earth response near 1 cycle per siderial day is found to be consistent with the nearly diurnal free wobble. However, the influence of the ocean on the small but crucial Ψ1 tide is uncertain. Anomalous responses are observed at several other frequencies but except for the case of ρ1 it is argued that anomalous ocean tides are plausible and could therefore explain the observations.

Summary The superconducting gravimeter has been calibrated to an accuracy of 0-2 per celit and was used to measure the influence of the ocean tides on the tides of the solid earth at two locations in southern California. These measurements, which show a signal to noise ratio of 70db in the 1 and 2 cycle per day band, and the accurate calibration of the gravimeter make possible a quantitative test of ocean load calculations for the 0, and M, constituents and the ocean models upon which they are based. We have computed the ocean load effect by using Farrell's Green's functions and modifications of previously published ocean co-tidal charts. The agreement between observed and computed earth tides is within 0.2 per cent and corroborates the placement of an M, amphidrome at 1500 km southwest of San Diego. If the amplitudes of the computed tides are correct it also sets an upper limit of 0.1" on the phase shifts of the solid earth tides. We have also observed the loading effect on the coast due to the nonlinear MI ocean tide.