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There has been an increase in the number of units providing anaesthesia for magnetic resonance imaging and the strength of magnetic resonance scanners, as well as the number of interventions and operations performed within the magnetic resonance environment. More devices and implants are now magnetic resonance imaging conditional, allowing scans to be undertaken in patients for whom this was previously not possible. There has also been a revision in terminology relating to magnetic resonance safety of devices. These guidelines have been put together by organisations who are involved in the pathways for patients needing magnetic resonance imaging. They reinforce the safety aspects of providing anaesthesia in the magnetic resonance environment, from the multidisciplinary decision making process, the seniority of anaesthetist accompanying the patient, to training in the recognition of hazards of anaesthesia in the magnetic resonance environment. For many anaesthetists this is an unfamiliar site to give anaesthesia, often in a remote site. Hospitals should develop and audit governance procedures to ensure that anaesthetists of all grades are competent to deliver anaesthesia safely in this area.

Solid–liquid interface (SLI) properties of the Ni–Zr B33 phase were determined from molecular dynamics simulations. In order to perform these measurements, a new semi-empirical potential for Ni–Zr alloy was developed that well reproduces the material properties required to model SLIs in the Ni50.0Zr50.0 alloy. In particular, the developed potential is shown to provide that the solid phase emerging from the liquid Ni50.0Zr50.0 alloy is B33 (apart from a small fraction of point defects), in agreement with the experimental phase diagram. The SLI properties obtained using the developed potential exhibit an extraordinary degree of anisotropy. It is observed that anisotropies in both the interfacial free energy and mobility are an order of magnitude larger than those measured to date in any other metallic compound. Moreover, the [0 1 0] interface is shown to play a significant role in the observed anisotropy. Our data suggest that the [0 1 0] interface simultaneously corresponds to the lowest mobility, the lowe...

We study correlations between the solid-liquid interface (SLI) free energy and bulk material properties (melting temperature, latent heat, and liquid structure) through the determination of SLI free energies for bcc and hcp metals from molecular dynamics (MD) simulation. Values obtained for the bcc metals in this study were compared to values predicted by the Turnbull, Laird, and Ewing relations on the basis of previously published MD simulation data. We found that of these three empirical relations, the Ewing relation better describes the MD simulation data. Moreover, whereas the original Ewing relation contains two constants for a particular crystal structure, we found that the first coefficient in the Ewing relation does not depend on crystal structure, taking a common value for all three phases, at least for the class of the systems described by embedded-atom method potentials (which are considered to provide a reasonable approximation for metals).

The number of anaesthetists who are involved in magnetic resonance (MR) units is increasing. Magnetic resonance systems are becoming more powerful and interventional procedures are now possible. This paper updates information relating to safety terminology, occupational exposure, reactions to gadolinium-based contrast agents and the risk of nephrogenic systemic fibrosis. Magnetic resonance examinations of patients with pacemakers are still generally contra-indicated but have been carried out in specialist centres under strictly controlled conditions. As availability of MR increases, so the education of anaesthetists, who are occasionally required to provide a service, must be considered. Anaesthesia in MR units was first described in the 1980s. Guidelines on the provision of anaesthetic services in MR units were published by the Association of Anaesthetists of Great Britain and Ireland (AAGBI) in 2002 [1]. Since then, the number of hospitals with MR units, and hence the number of patients requiring anaesthesia for MR, has increased. While the issues relating to setting up anaesthetic services in MR have not changed, there have been a number of developments that warrant this update: Safety terminology and guidelines have changed. MR systems utilise higher magnetic-field strengths and more open designs are available. Interventional and intra-operative MR are now routine in some centres. Mobile MR scanners are increasingly used to reduce waiting lists. Although still generally contra-indicated, some patients with pacemakers have been scanned under strictly controlled conditions in specialist centres. ‘MR safe’ medical implants are now being produced. New equipment is now available for use in MR. Out-of-hours availability of MR investigations has increased. Reports of allergic reactions to MR contrast media have increased. Gadolinium based contrast agents (Gd-CAs) are associated with a varying degree of risk of nephrogenic systemic fibrosis in patients with impaired renal function. Safety guidelines and legislation In 2007 the Medicines and Healthcare products Regulatory Agency (MHRA) updated safety guidance as a Device Bulletin [2]. Three terms are now to be used as standard in an attempt to remove any ambiguity caused by the old MR compatible system. These terms are MR conditional, MR safe and MR unsafe. MR conditional refers to an item that has been demonstrated to pose no known hazards in a specified MR environment with specified conditions of use. Many items in the MR environment will now be marked as MR conditional, and the conditions under which they can be safely used must accompany the device. This change of terminology has come about because of reports of injuries and problems with MR compatible equipment [3]. Conditions that define the specified MR environment include main magnetic field strength, spatial magnetic field gradient, dB/dt (time rate of change of the magnetic field), radio frequency (RF) field strength, and specific absorption rate. Additional conditions, including specific configurations of the item of equipment, may be required. Equipment is designated as MR safe if it presents no safety hazard to patients or personnel when it is taken into the MR examination room, provided that instructions concerning its use are correctly followed. This does not, however, guarantee that it will function normally and not interfere with the correct operation of the MR imaging equipment, with degradation of image quality. New equipment, such as infusion pumps [4], warming mattresses and temperature probes are now available. It is important to understand the manufacturers’ instructions of all equipment that is brought into the vicinity of the MR scanner. It should be recognised that the supervising MR radiographer is responsible operationally for MR safety within the controlled area and that anaesthetic staff should defer to him/her in relation to MR safety matters, in particular control of access of staff and equipment into the controlled area. Where staff are given access codes or swipe-card access to the controlled area, they should not be shared with others, nor should they provide access to others unless specifically authorised to do so. Inspired oxygen concentration The use of 100% O2 during anaesthesia should be reported to the reporting radiologist as this can produce an artefact in the form of an abnormally high signal in cerebrospinal fluid (CSF) spaces in the T2 weighted fluid attenuated inversion recovery (FLAIR) sequence.

Given two sequences of length n over a finite alphabet A of size |A| = d, the D 2 statistic is the number of k-letter word matches between the two sequences. This statistic is used in bioinformatics for EST sequence database searches. Under the assumption of independent and identically distributed letters in the sequences, Lippert, Huang and Waterman (2002) raised questions about the asymptotic behavior of D 2 when the alphabet is uniformly distributed. They expressed a concern that the commonly assumed normality may create errors in estimating significance. In this paper we answer those questions. Using Stein's method, we show that, for large enough k, the D 2 statistic is approximately normal as n gets large. When k = 1, we prove that, for large enough d, the D 2 statistic is approximately normal as n gets large. We also give a formula for the variance of D 2 in the uniform case.

The effect of aerosols on clouds and their radiative properties is one of the largest uncertainties in our understanding of radiative forcing. A recent study has concluded that better characterisation of pristine, natural aerosol processes leads to the largest reduction in these uncertainties. Antarctica, being far from anthropogenic activities, is an ideal location for the study of natural aerosol processes. Aerosol measurements in Antarctica are often limited to boundary layer air-masses at spatially sparse coastal and continental research stations, with only a handful of studies in the sea ice region. In this paper, the first observational study of sub-micron aerosols in the East Antarctic sea ice region is presented. Measurements were conducted aboard the ice-breaker Aurora Australis in spring 2012 and found that boundary layer condensation nuclei (CN3) concentrations exhibited a five-fold increase moving across the Polar Front, with mean Polar Cell concentrations of 1130 cm−3 – higher than any observed elsewhere in the Antarctic and Southern Ocean region. The absence of evidence for aerosol growth suggested that nucleation was unlikely to be local. Air parcel trajectories indicated significant influence from the free troposphere above the Antarctic continent, implicating this as the likely nucleation region for surface aerosol, a similar conclusion to previous Antarctic aerosol studies. The highest aerosol concentrations were found to correlate with low pressure systems, suggesting that the passage of cyclones provided an accelerated pathway, delivering air-masses quickly from the free-troposphere to the surface. After descent from the Antarctic free troposphere, trajectories suggest that sea ice boundary layer air-masses travelled equator-ward into the low albedo Southern Ocean region, transporting with them emissions and these aerosol nuclei where, after growth, may potentially impact on the region's radiative balance. The high aerosol concentrations and their transport pathways described here, could help reduce the discrepancy currently present between simulations and observations of cloud and aerosol over the Southern Ocean.

The solid-liquid interface (SLI) free energy was determined from molecular dynamics (MD) simulation for several body centered cubic (bcc) metals and B2 metallic compounds (space group: Pm3̄m; prototype: CsCl). In order to include a bcc metal with a low melting temperature in our study, a semi-empirical potential was developed for Na. Two additional synthetic "Na" potentials were also developed to explore the effect of liquid structure and latent heat on the SLI free energy. The obtained MD data were compared with the empirical Turnbull, Laird, and Ewing relations. All three relations are found to predict the general trend observed in the MD data for bcc metals obtained within the present study. However, only the Laird and Ewing relations are able to predict the trend obtained within the sequence of "Na" potentials. The Laird relation provides the best prediction for our MD data and other MD data for bcc metals taken from the literature. Overall, the Laird relation also agrees well with our B2 data but requires a proportionality constant that is substantially different from the bcc case. It also fails to explain a considerable difference between the SLI free energies of some B2 phases which have nearly the same melting temperature. In contrast, this difference is satisfactorily described by the Ewing relation. Moreover, the Ewing relation obtained from the bcc dataset also provides a reasonable description of the B2 data.

High-energy x-ray diffraction measurements of undercooled, electrostatically levitated Ni50Zr50 liquid droplets were performed. The observed solidification pathway proceeded through the nucleation and growth of the metastable B2 phase, which persisted for several seconds before the rapid appearance of the stable B33 phase. This sequence is shown to be consistent with predictions from classical nucleation theory using data obtained from molecular dynamics (MD) simulations. A plausible mechanism for the B2–B33 transformation is proposed and investigated through further MD simulations.

Direct current resistivity traversing has been used to characterise the nature of the saline interface at Te Horo on the Kapiti Coast in New Zealand. The results show that the interface in the vicinity of the settlement, which relies on bores for potable water, has intruded inland 10 m further than in undeveloped areas. Resistivity traversing has been particularly successful in defining subsurface areas of higher salinity by providing a two-dimensional image of the bulk resistivity structure. The results of the resistivity surveys are supported by bore water chemistry, which show evidence of saltwater mixing. Bores on beachfront properties have concentrations of up to 1% seawater. A resistivity formation factor has been derived to allow the pore fluid resistivity to be estimated for future coastal surveys. The results also illustrate the problems associated with using standard models to predict the location of the saline interface when small amounts of diffusive mixing occur.

Subarachnoid haemorrhage is a common neurological emergency, which carries a high morbidity and mortality. It is usually caused by rupture of an intracerebral aneurysm or, less commonly, an arteriovenous malformation. Although most patients present to a non-neurosurgical hospital, they often require urgent neurosurgical or neuroradiological intervention. Whilst awaiting transfer to a neurological centre, active management of the patient must be instituted. This should include confirmation of the diagnosis with CT imaging, lumbar puncture or both, and recognition of the complications of subarachnoid haemorrhage, which include hydrocephalus, further haemorrhage and cerebral vasospasm. Medical management is directed towards maintaining adequate cerebral perfusion pressure whilst avoiding large increases in arterial blood pressure. Nimodipine therapy must be started early in an attempt to prevent cerebral vasospasm. The treatment options available at the neurological centre include surgical treatment or endovascular obliteration of the aneurysm or arteriovenous malformation.

Estimates of the rate of production of excited oxygen atoms due to the photolysis of ozone J(O1D) have been derived from radiation measurements carried out at Cape Grim, Tasmania (40.6° S, 144.7° E). These estimates agree well with measurements made during SOAPEX-II and with model estimates of clear sky photolysis rates. Observations spanning 2000–2005 have been used to quantify the impact of season, cloud and ozone column amount. The annual cycle of J(O1D) has been investigated via monthly means. These means show an inter-annual variation (monthly standard deviation) of 9%, but in midsummer and midwinter this reduces to 3–4%. Factors dependent upon solar zenith angle and satellite derived total ozone column explain 87% of the observed signal variation of the individual measurements. The impact of total column ozone, expressed as a Radiation Amplification Factor (RAF), is found to be ~1.45, in agreement with model estimates. This ozone dependence explains 20% of the variation observed at medium solar zenith angles (30–50°). The impact of clouds results in a median reduction of 14% in J(O1D) for the same solar zenith angle range. At all solar zenith angles less than 50° approximately 10% of measurements show enhanced J(O1D) due to cloud scattering and this fraction climbs to 25% at higher solar angles. Including estimates of cloudiness derived from Long Wave Radiation measurements resulted in a statistically significant fit to observations but the quality of the fit did not increase significantly as measured by the reduced R2.

Nitrous oxide (N2O) fluxes for south-easternAustralia have been estimated using a combination ofthe in situ N2O and radon (Rn) measurementsmade at the Cape Grim Baseline Air Pollution Station,in north-west Tasmania. The average N2O fluxesfrom the south-eastern mainland of Australia and fromTasmania over the nine years of record analysed (1985–1993) have beenfound to be 130 ± 30 kgN km-2yr-1 and 160 ± 45 kgN km-2yr-1respectively. These fluxes are larger than expectedand a significant dependence of the flux on rainfallis observed, with greater fluxes in the spring (October–December) andduring periods of positive SouthernOscillation Index. A large flux (1,300 ± 500kgN km-2 yr-1) from a nearby island (KingIsland) was also estimated from the data record,indicating a strong source, although the small size ofthe island means that it is not a significant sourcefor Australia.

Initially, a set of guidelines for the use of ultrasound contrast agents was published in 2004 dealing only with liver applications. A second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some non-liver applications. Time has moved on, and the need for international guidelines on the use of CEUS in the liver has become apparent. The present document describes the third iteration of recommendations for the hepatic use of contrast enhanced ultrasound (CEUS) using contrast specific imaging techniques. This joint WFUMB-EFSUMB initiative has implicated experts from major leading ultrasound societies worldwide. These liver CEUS guidelines are simultaneously published in the official journals of both organizing federations (i.e., Ultrasound in Medicine and Biology for WFUMB and Ultraschall in der Medizin/European Journal of Ultrasound for EFSUMB). These guidelines and recommendations provide general advice on the use of all currently clinically available ultrasound contrast agents (UCA). They are intended to create standard protocols for the use and administration of UCA in liver applications on an international basis and improve the management of patients worldwide.

This paper describes organotitanium derivatives resulting from the reactions of titanocene dichloride with derivatives of dinenzothiophene (DBT). Lithium cleavage of DBT gives 2,2′-Li(LiS)C12H8 which reacts with (C5H5)2TiCl2 to give the metallacyclic complex (C5H5)2TiSC12H8 (1). Two side products were isolated in smaller amounts, the thiolates (C5H5)2Ti(SC6H4-2-Ph)2 (2) and (C5H5)2Ti(SC6H4-2-Ph)Cl. DNMR studies showed that 1 and its MeC5H4 analog 3 are stereochemically non-rigid as a result of the folding of the organosulfur chelate. The structure of (MeC5H4)2TiSC12H8 was verified by single crystal X-ray diffraction; the complex consists of the expected (MeC5H4)2Ti moiety coordinated to the carbon and sulfur of the ring-cleaved DBT. An attempt to generate 2,2′-Li(LiS)C12H8 via the double metalation of 2-phenylbenzenethiol with two equivalents of BuLi in the presence of TMEDA, followed by treatment with (C5H5)2TiCl2, gave the deep green complex (C5H5)2TiS2C24H16 (4). Single crystal X-ray diffraction indicated that 4 is a complex of the 2,2-dimercapto-3,3′-diphenylbiphenyl ligand (2,2′-(LiS)2-3,3′-Ph2C12H6), resulting from the coupling of two molecules of 1-Ph-2-LiS-3-LiC6H3. DNMR studies showed that this complex is stereochemically rigid. The free dithiol was liberated by treatment of 4 with anhydrous HCl. The complex of the unsubstituted 2,2′-dimercaptobiphenyl was prepared by treatment of 2,2′-Li(LiS)C12H8 with one equivalent of sulfur followed by quenching the reaction with titanocene dichloride to give (C5H5)2TiS2C12H8 (6). Electrochemical studies show that the TiIV/III couple is reversible for all new compounds; the reduction potentials are lower for the chelating dithiolates and highest for the C-S chelate complexes 1 and 3.

The design and total convergent synthesis are described for the leading representatives of the new class of analogs of cholecalciferol with the CD-ring system replaced with a two-carbon aliphatic spacer. The leading representatives of C 21 retiferols (RAD 1 and RAD 2 ) were obtained from a ring fragment derived from vitamin D and a chain fragment obtained from S -(−)-β-citronellol.

The authors report the design and synthesis of a novel N[sub 2]S[sub 2] ligand system for the formation of Re(V) oxo and [sup 99]Tc(V) oxo complexes. An S,S[prime]-bis(trityl) N-benzyl monoamine-monoamide (Bn-MAMA[prime]-Tr[sub 2]) complex was prepared in four steps from commercially available cysteamine hydrochloride. S-Trityl protection of cysteamine hydrochloride followed by N-acylation of the amine function with bromoacetyl bromide provided the corresponding primary bromide, which was then reacted with additional S-trityl-protected cysteamine to provide the S,S[prime]-bis(trityl) monoamine-monoamide ligand (MAMA[prime]-Tr[sub 2]). N-Alkylation by nucleophilic displacement with the methanesulfonate of benzyl alcohol gave the N-benzyl MAMA[prime] ligand in the thiol-protected form. Metal incorporation to provide the title compounds consisted of deprotection of the sulfur atoms with Hg(OAc)[sub 2] followed by H[sub 2]S to provide free bis(thiol) which could then be reacted with the corresponding metals in basic methanolic medium to provide a mixture of syn- and anti-substituted metal(V) oxo products (Bn-MAMA[prime]-M=O, metal = Re, [sup 99]Tc). The two disastereomers could be differentiated by proton NMR due to the upfield shifts of the methylene protons on the endo (anti) phenylmethyl substitutent (2.7 and 3.4 ppm) relative to those of the exo- (syn-) substituted isomer (4.7 and 5.1 ppm). An unambiguous structural assignment of themore » N-benzyl-MAMA-metal(V)-oxo compounds was established by an X-ray diffraction study on the rhenium compounds 8a-Re (syn) and 8b-Re (anti).« less

BACKGROUND--Acute inhalation of clinical doses of salbutamol in normal volunteers increases resting metabolic rate by up to 20% above control values. This study was designed to see if chronic treatment with salbutamol causes a sustained increase in metabolic rate and whether it modifies the acute thermogenic response to the drug. METHODS--The effects of chronic inhaled salbutamol on resting oxygen consumption (VO2) and carbon dioxide output (VCO2) were studied in seven normal subjects (age 20-47 years, weight 52-105 kg, five men). An open canopy method of indirect calorimetry was used to measure VO2, VCO2, and respiratory quotient (RQ). Subjects inhaled two puffs of salbutamol or placebo four times a day in a double blind manner. Measurements of resting VO2 and VCO2 after 10 days of salbutamol were compared with the values after 10 days of placebo and with those taken at the start of the study. At the end of each treatment period subjects inhaled eight puffs (800 micrograms) of salbutamol and the acute effects on VO2, VCO2 and RQ were monitored for one hour. RESULTS--Resting VO2, VCO2, and RQ were not significantly different at the end of the salbutamol and placebo periods but the acute response to eight puffs of salbutamol was abolished by regular inhalation. The mean VO2 integrated over one hour after 800 micrograms salbutamol given acutely was different (241.3 and 210.7 ml/kg/h in the placebo and salbutamol groups respectively). Differences were not significant between placebo and salbutamol groups for changes in VCO2, heart rate, blood pressure, and RQ after acute inhalation. CONCLUSION--Regular treatment with inhaled salbutamol (800 micrograms/day) does not cause a sustained increase in resting metabolic rate but prevents the increase in VO2 that occurs after acute inhalations in normal subjects.

The structure of the 10-I-4 periodonium ion of bis[α,α-bis(trifluoromethyl)benzenemethanolato(2-)-C 2 , O α ]iodine (1+) triflate, salt 1a, was confirmed by an X-ray crystallographic structure determination. The periodonium ion of 1a was the first example of a stable cationic 10-I-4 species lacking fluorine ligands. In contrast to other periodonium ions, that of 1a is not hydrolyzed by atmospheric moisture nor by water in neutral or acidic media. It does not react with weak nucleophiles such as pyridine or methanol.The lack of reactivity of the periodonium ion of 1a is better rationalized by comparision with other spirobicyclic 10-X-4 systems than with other known 12-I-5 or 10-I-4 species.Stricking parallels between the structures and properties of 10-X-4 species with identical bidentate ligands support the idea that properties of isovalent and isostructural hypervalent 10-X-4 species are predictable on the basis of ligand properties.Indeed the most stricking aspect of the reactivity of the periodonium ion of 1a is how little it resembles the reactivity of other the reactivity of other known iodine species in the same oxidation state.This is direct result of the specific geometry and electron distribution imposed on the central atom of a 10-X-4 species by the spirobicyclic ligand system, which was designed for specific stabilizing features for Ψ-TBP and TBP 10-X-L systems

A technique for calibrating spectral radiometers measuring global (2π sr) irradiance using solar irradiance at the top of the atmosphere as the absolute irradiance reference is reported. In addition to providing a calibration at all measured wavelengths, the technique provides a direct measure of the angular response of the radiometer. For instruments that can be used to measure the ultraviolet-B region, the calibration also provides an estimate of the ozone column amount.

The structure of the 10-I-4 periodonium ion of bis[α,α-bis(trifluoromethyl)benzenemethanolato(2-)-C 2 , O α ]iodine (1+) triflate, salt 1a, was confirmed by an X-ray crystallographic structure determination. The periodonium ion of 1a was the first example of a stable cationic 10-I-4 species lacking fluorine ligands. In contrast to other periodonium ions, that of 1a is not hydrolyzed by atmospheric moisture nor by water in neutral or acidic media. It does not react with weak nucleophiles such as pyridine or methanol.The lack of reactivity of the periodonium ion of 1a is better rationalized by comparision with other spirobicyclic 10-X-4 systems than with other known 12-I-5 or 10-I-4 species.Stricking parallels between the structures and properties of 10-X-4 species with identical bidentate ligands support the idea that properties of isovalent and isostructural hypervalent 10-X-4 species are predictable on the basis of ligand properties.Indeed the most stricking aspect of the reactivity of the periodonium ion of 1a is how little it resembles the reactivity of other the reactivity of other known iodine species in the same oxidation state.This is direct result of the specific geometry and electron distribution imposed on the central atom of a 10-X-4 species by the spirobicyclic ligand system, which was designed for specific stabilizing features for Ψ-TBP and TBP 10-X-L systems

In this paper we describe a new method for estimating trace gas emissions from large vegetation fires using measurements of aerosol optical depth from the MODIS instruments onboard NASA's Terra and Aqua satellites, combined with the atmospheric chemical transport model MOZART. The model allows for an estimate of double counting of enhanced levels of aerosol optical depth in consecutive satellite overpasses. Using this method we infer an estimated total emission of 10±3 Tg of carbon monoxide from the Canberra fires of 2003. Emissions estimates for several other trace gases are also given. An assessment of the uncertainties in the new method is made and we show that our estimate agrees (within expected uncertainties) with estimates made using current conventional methods of multiplying together factors for the area burned, fuel load, the combustion efficiency and the emission factor for carbon monoxide. The new method for estimating emissions from large vegetation fires described in this paper has some significant uncertainties, but these are mainly quantifiable and largely independent of the uncertainties inherent in conventional techniques. Thus we conclude that the new method is a useful additional tool for characterising emissions from vegetation fires.

Ion-beam-figuring techniques have been applied to fabricate high-power transmission gratings for use in photoacoustic spectroscopy. A thin-film assembly of SiO(2) and TiO(2) layers on an SiO(2) substrate provides a high-reflecting characteristic at a desired wavelength. With standard photolithographic techniques a grating pattern is developed on the surface of the assembly then ion etched with ion-beam-figuring techniques. These gratings exhibit an increased factor of 25 in acoustic signal levels when compared with previously used chemical-etched silicon gratings. This increase was obtained owing to higher transmission, less thermal distortion, and the ability to withstand higher incident power levels.