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We report an extensive computational and spectroscopic study of several fluoropyridine-HCl complexes, and the parent, pyridine-HCl system. Matrix-IR spectra for pentafluoropyridine-HCl, 2,6-difluororpyridine-HCl, and 3,5-difluororpyridine-HCl in solid neon exhibit shifts for the H-Cl stretching band that parallel the effects of fluorination on hydrogen-bond strength. Analogous spectral shifts observed across various host environments (solid neon, argon, and nitrogen) for pentafluoropyridine-HCl and 2,6-difluororpyridine-HCl convey a systematically varying degree of matrix stabilization on the hydrogen bonds in these complexes. An extended quantum-chemical study of pyridine-HCl and eight fluorinated analogs, including 2-, 3-, and 4-fluoropyridine-HCl, 2,6- and 3,5-difluororpyridine-HCl, 2,4,6- and 3,4,5-trifluropyridine-HCl, as well as pentafluoropyridine-HCl, was also performed. Equilibrium structures and binding energies for the gas-phase complexes illustrate two clear trends in how fluorine substitution affects hydrogen bond strength; increasing fluorination weakens these interactions, yet substitution at the 2- and 6-positions has the most pronounced effect. Bonding analyses for a select subset of these systems reveal shifts in electron density that accompany hydrogen bonding, and most notably, the values of the electron density at the N-H bond critical points among the stronger systems in this subset significantly exceed those typical for moderately strong hydrogen-bonds. We also explored the effects of dielectric media on the structural and bonding properties of these systems. For pyridine-HCl, 3-fluoropyridine-HCl, and 3,5-difluororpyridine-HCl, a transition to proton transfer-type structures is observed at

The article of record as published may be found at http://dx.doi.org/10.1007/s41939-018-0019-7 Material surfaces can be modified to become superhydrophobic using different techniques. Test equipment is necessary to assess the effectiveness of a superhydrophobic surface against frictional drag force. Because the frictional drag force is very small, especially for a sample size to be tested at a laboratory level, a traditional water channel system is not suitable. As a result, a new test setup was designed and fabricated to measure the reduction in the skin frictional drag force on such a superhydrophobic metallic surface. Two different types of sensors were considered. The first one was a spring-based displacement sensor and the other was a spring-less displacement sensor. The developed test setup can have the flow speed with a range of Reynolds numbers up to 70,000 with respect to the test specimen. In this range, the change in the frictional drag force was measured for superhydrophobic surfaces. A microscope was also used to check any change in the air film on the superhydrophobic surface as the flow speed was increased. Ms. Sarwat Chappell at the Office of Naval Research

Introduction Statutory duty of candour was introduced in November 2014 for NHS bodies in England. Contained within the regulation were definitions regarding the threshold for what constitutes a notifiable patient safety incident. However, it can be difficult to determine when the process should be implemented. The aim of this survey was to evaluate the interpretation of these definitions by British neurosurgeons. Materials and methods All full (consultant) members of the Society of British Neurological Surgeons were electronically invited to participate in an online survey. Surgeons were presented with 15 cases and asked to decide in the case of each one whether they would trigger the process of duty of candour. Cases were stratified according to their likelihood and severity. Results In all, 106/357 (29.7%) members participated in the survey. Responses varied widely, with almost no members triggering the process of duty of candour in cases where adverse events were common (greater than 10% likelihood) and required only outpatient follow-up (7/106; 6.6%), and almost all members doing so in cases where adverse events were rare (less than 0.1% likelihood) and resulted in death (102/106; 96.2%). However, there was clear equipoise in triggering the process of duty of candour in cases where adverse events were uncommon (0.1–10% likelihood) and resulted in moderate harm (38/106; 35.8%), severe harm (57/106; 53.8%) or death (49/106; 46.2%). Conclusion There is considerable nationwide variation in the interpretation of definitions regarding the threshold for duty of candour. To this end, we propose a framework for the improved application of duty of candour in clinical practice.

The article of record may be found at https://doi.org/10.1080/1478422X.2017.1348090 With superhydrophobic properties being extended to a variety of metallic substrates through the process of ablation due to femtosecond laser surface processing (FLSP), it is important to understand corrosion behaviour of such a processed material. The material was tested through the use of an accelerated corrosion fog chamber using both treated and untreated aluminium alloy samples. During the accelerated corrosion testing, the FLSP-treated sample suffered from pitting corrosion at a rate faster than the untreated sample, effectively removing the surface treatment. While there are significant hydrodynamic benefits to this material, the elevated corrosion rates raise concerns about the resiliency of this surface treatment.

Background The Symmetry Bypass System Aortic Connector (St Jude Medical, Inc) is a novel device for the construction of sutureless proximal anastomoses. The connector allows attachment of saphenous vein grafts to the aorta without requiring aortic clamping. We report our initial clinical experience with this device. Methods In a 2-month period from May to July 2001, a total of 139 consecutive proximal anastomoses were performed in 67 patients using the connector. All procedures were performed on a beating heart without cardiopulmonary bypass or any aortic clamping. Intraoperative variables and postoperative results were prospectively collected and retrospectively analyzed. Results Of 139 consecutive proximal anastomoses 138 (99.3%) were successfully completed with the device. One anastomosis required suture revision because of misdeployment. Six anastomoses (4.3%) required an additional suture for leak. Predeployment problems included connector loading/preparation malfunction in 10 grafts (7.2%), five because of human error and five technical failure. There was no operative mortality, perioperative myocardial infarction, or stroke. Vessels bypassed included the circumflex system (n = 59), right coronary artery and branches (n = 48), diagonal branch (n = 26), and left anterior descending coronary artery (n = 6). At a mean follow-up of 7 months, survival was 94.1% and survival free of major adverse cardiac and cerebrovascular events (MACCE) was 88.1%. Conclusions Initial clinical experience with a sutureless proximal saphenous vein graft to aorta anastomosis performed with a mechanical connector demonstrates safety, reliability, and ease of use. Surmounting a brief learning curve improves the subtleties of device loading and deployment. Further benefits will be determined in an ongoing randomized study.

Conventional catheter-based systems used for ambulatory esophageal pH monitoring have been reported to affect patient behavior. As physical activity has been associated with gastroesophageal reflux disease (GERD), there is a risk that abnormal behavior will degrade the value of this diagnostic investigation and consequent management strategies. The aim of this study was to quantify the effect of conventional pH monitoring on behavior and to investigate the temporal association between activity and reflux. A total of 20 patients listed for 24 hours pH monitoring underwent activity monitoring using a lightweight ear-worn accelerometer (e-AR sensor, Imperial College London) 2 days prior to, and during their investigation. PH was measured and recorded using a conventional nasogastric catheter and waist-worn receiver. Daily activity levels, including subject-specific activity intensity quartiles, were calculated and compared. Physical activity was added to the standard pH output to supplement interpretation. Average patient activity levels decreased by 26.5% during pH monitoring (range -4.5 to 51.0%, P = 0.036). High-intensity activity decreased by 24.4% (range -4.0 to 75.6%, P = 0.036), and restful activity increased on average by 34% although this failed to reach statistical significance (-24.0 to 289.2%, P = 0.161). Some patients exhibited consistent associations between bouts of activity and acidic episodes. The results of this study support the previously reported reduction in activity during ambulatory esophageal pH monitoring, with the added reliability of objective data. In the absence of more pervasive pH monitoring systems (e.g. wireless), quantifying activity changes in the setting of activity-induced reflux might guide the physicians' interpretation of patient DeMeester scores resulting in more appropriate management of GERD.

The theory of quantum electrodynamics has presented a complete calculation of the energy levels of positronium (Ps, e + e − ) up to the order R ∞ α 4 . The annihilation rates for para -Ps (1 1 S 0 ) and ortho -Ps (1 1 S 1 ) are completely known up to the order R ∞ α 5 and R ∞ α 6 , respectively. The present experimental uncertainty for spectroscopic results is 5–100 times larger than the theoretical uncertainty. For the annihilation rates the experimental situation is even worse. The theoretical predictions have presently reached a level of precision which is a challenge to experimentalists! The experimental uncertainty for the fine- and hyperfine transitions in the Ps atom is determined by the natural line width. An improvement is only possible with better statistics, i.e. higher positron intensities. For the annihilation rate of ortho -Ps there exist controversial measurements. Here completely new experiments are necessary which differ from the old measurements by possible systematic errors. All new proposals need high positron intensities which can be conveniently produced by bremsstrahlung and pair conversion in the beam dump of medium energy electron accelerators.

Several business sectors have identified the potential benefits of a landscape/urban assessment based upon the objective appraisal of the interaction of the cultural and natural landscapes. This paper describes a recently approved project (PLAINS) funded by DGXII of the European Union under the Framework IV Environment and Climate Programme. The aim of this project is to identify the benefits of introducing satellite Earth Observation data into the landscape assessment process and to develop a decision support system that will provide for landscape/urban classification tuned to satisfy specific customer requirements. The system will also allow the exploration of impact assessment (‘what if’) scenarios. The project involves three different business sectors who have inherently similar requirements in landscape assessment. The ‘customer’ organisations involved in the project cover the sectors: regional planning authorities, Estate Agents and tourism. In all, there are 13 partners involved in the project from five countries (UK, Denmark, Germany, Italy, Poland). The initial development of the system will use test sites in the counties of Hereford and Worcester in the UK, with subsequent validation being carried out at sites in Italy (Province of Savona), Germany and Poland.

High densities of ultra cold positrons are required for applications such as positronium production, scattering processes with atoms, surface analysis, cooling of highly charged ions and antihydrogen production. At the University of Aarhus, Denmark, an accelerator based slow positron source delivers about 5 × 104 positrons within a 10 ns bunch at a repetition rate of 10 Hz. The energy spread is below 1 eV and the beam diameter is about 1 mm. The positron bunches shall be injected into a 6-T Penning trap at the temperature of liquid helium. The bunches can be captured at nearly 100% efficiency by a fast time variation of the trap potential. The cyclotron motion cools down by synchrotron radiation with a time constant of 80 ms. The axial motion can be cooled by coupling to the radial motion or by resistive cooling in a tuned circuit. By stacking of 100 pulses about 5 × 106 positrons can be accumulated within 10 s. After this time most of the positrons have cooled down sufficiently that the trapping cycle can be started again. At the anticipated accumulation rate a positron plasma at the space charge limit should be obtainable within 1 h.

To prepare dense bunches of lead ions for the LHC it has been proposed to accumulate the 4.2 MeV/u linac beam in a storage ring with electron cooling. A series of experiments is being performed in the low-energy ring LEAR to test this technique. First results were already reported at the Beam Crystallisation Workshop in Erice in November 1995. Two more recent runs to complement these investigations were concerned with: further study of the beam lifetime; the dependence of the cooling time on optical settings of the storage ring and on neutralization of the electron beam; and tests in view of multiturn injection. New results obtained in these two runs in December 1995 and in April 1996 will be discussed in this contribution.

This report presents results of experiments performed between 1994 and 1996 by a CERN/JINR collaboration, aimed to study the problem of the generation of intense electron beams whose space charge is neutralised by the residual gas ions. The problem is related to the development of electron cooling methods. The large space charge potential for high density electron beams is a significant drawback for the cooling process. In order to reduce this effect, an electron beam neutralisation system has been implemented on the LEAR cooler and the JINR test bench. In this paper we briefly discuss the physics of the neutralisation process, technological aspects of neutralisation, the measurement techniques and the results.

A large space-charge is detrimental to the cooling process of a dense beam. Generation of a neutralised electron beam is restricted by beam-drift instability. To suppress this instability, active methods are used: a kicker with a transverse electric field (shaker) and longitudinal electrodes placed in the vacuum chamber and in the gun region expel secondary electrons. Results of experiments dedicated to the development of beam stabilisation on the JINR test bench and in the electron cooling system at LEAR are discussed.

The methods to produce positrons and positronium are shortly reviewed. Different sources for positrons are compared. Implantation, diffusion and emission of positrons and some typical moderators are discussed. Special consideration is given to accelerator based sources, to the design of conversion targets, to the conversion efficiency and to the problems of thermal power dissipation. Finally the possible accumulation of large numbers of positrons by using pulsed accelerators is outlined.

Thegj factor measurement of hydrogenic ions in the 1s ground state is with an expected accuracy of 10−7 a sensitive test of bound state QED. We expect to determine the deviations from the free electron value, caused by relativistic and radiative corrections, up to the orderα/4π(Zα)2 with an accuracy of 1%. As a first step, light ions like C5+ will be investigated. Later on, heavier hydrogenic ions up to U91+ will be examined using the accelerator facilities at GSI in Darmstadt.

Electric dipole transitions in the microwave range have been induced between the fine-structure levels of positronium in the excited staten=2. As an indication of the transitions, we used the increase in Lyman-α radiation when the metastable 23S1-level is depopulated. The results for the transitions 23S1→23P0,1,2 areΝ 0=18499.65±1.20±4.00 MHz,Ν 1=13012.42 ±0.65±1.54 MHz andΝ 2=8624.38±0.54±1.40 MHz. The first error is statistical and the second systematic. The precision of the present measurement has improved by a factor of 3, compared to previous data. Recent bound state QED-calculations have been extended to the orderR t8 α 4lnα −1. The not yet completely calculated orderR t8 α 4 is estimated to contribute less than 1 MHz. Our experimental results are in good agreement with theory. By applying a weak magnetic field, we were able to observe the transition 23S1→21P1 which is strictly forbidden byC-invariance in zero field. Our result, corrected for Zeeman- and motional Starkeffect, isΝ 3=11180.0±5.0±4.0 MHz. An upper limit for theC-violating matrix element of $$|\langle 2^1 P_1 |H_ \not\subset |2^3 P_1 \rangle |< 76$$ MHz could be deduced. Our experiment used moderated slow positrons from the bremsstrahlung and pair production of a pulsed electron linear accelerator (TEPOS facility at the university of Giessen).

The role of the 5'-untranslated region (5'UTR) in the replication of enteroviruses has been studied by using a series of poliovirus type 3 (PV3) replicons containing the chloramphenicol acetyltransferase reporter gene in which the 5'UTR was replaced by the 5'UTR of either coxsackievirus B4 or human rhinovirus 14 or composite 5'UTRs derived from sequences of PV3, human rhinovirus 14, coxsackievirus B4, or encephalomyocarditis virus. The results indicate that efficient replication of an enterovirus genome requires a compatible interaction between the 5'-terminal cloverleaf structure and the coding and/or 3'-noncoding regions of the genome. A crucial determinant of this interaction is the stem-loop formed by nucleotides 46 to 81 (stem-loop d). The independence of the cloverleaf structure formed by the 5'-terminal 88 nucleotides and the ribosome landing pad or internal ribosome entry site (IRES) was investigated by constructing a 5'UTR composed of the PV3 cloverleaf and the IRES from encephalomyocarditis virus. Chloramphenicol acetyltransferase gene-containing replicons and viruses containing this recombinant 5'UTR showed levels of replication similar to those of the corresponding genomes containing the complete PV3 5'UTR, indicating that the cloverleaf and the IRES may be regarded as functionally independent and nonoverlapping elements.

This note describes the design of a multiblock semi-anatomic phantom, which lends itself to a variety of radiotherapy dosimetry applications, in particular, the audit of external beam treatment planning and delivery. The basic building blocks of the phantom were formed from a variety of tissue substitute materials and could be assembled in many ways to model different cross-sections through the body.

The slow positron facility TEPOS at the Giessen electron LINAC (36 MeV, 120 µA) has been used to produce an intense beam of moderated positrons which is magnetically guided over a distance of 9 m. At a transportation energy of 100 eV about 106 slow e+/s could be extracted out of the magnetic field (0.01 T) and have been electrostatically focussed inside a microwave guide. A small fraction of the positrons form positronium in the excited staten=2. The spontaneous emission of Lyman-α photons (λ=243 nm) from the 2P-states is observed by a photomultiplier. Microwave induced fine-structure transitions 23S1©23P2,1,0 have been observed at 8617(2), 13010(3) and 18494(2) MHz by an increase of the Lyman-α counting rate. The present errors take into consideration only statistical contributions; systematic errors in the same order of magnitude may originate from frequency dependent variations of the microwave power. The observed linewidth exceeds the natural linewidth of 50 MHz by Doppler-effect and power broadening. Values around 100 MHz could be reached at the lowest applied power levels.

In view of a future antihydrogen programme at CERN, the options for producing MeV antiprotons are revisited. The current limitations, operational performances and foreseen improvements are detailed. An alternative scheme using a dedicated machine for production and deceleration is also discussed.

An important aspect of the low-energy physics programme at LEAR is the use of electron cooling for phase-space compression of the circulating ion beam [1–3]. In order to improve the reliability of the cooling device, a new electron beam collector has been developed in a collaboration between CERN and CAPT (Centre of Applied Physics and Technology) Lipetsk. The collector is designed to recuperate 3.3 A of 35 keV electrons with an efficiency better than 99.99%. It was constructed at the INP (Institute of Nuclear Physics) Novosibirsk workshop in accordance with a design produced by CAPT and the electron cooling team at CERN. The vacuum and electrical test of the collector were performed at Lipetsk. The device is now installed at LEAR and has undergone first reception tests in the machine.

The slow positron beam facility TEPOS at the 65 MeV electron linear accelerator in Giessen has been used to produce an intense beam of monoenergetic positrons. The impact energy of the positrons hitting the surface of a polycrystalline molybdenum foil has been varied between 0 and 470 eV. The authors observed the formation of n=2 positronium by the emitted Lyman- alpha radiation and its change as a function of the positron energy. They found a maximum yield of excited positronium at an implantation energy of (60+or-20) eV. The yield decreased to 50% of the maximum value at about 200 eV.

Fine structure transitions in the first excited state of positronium (Ps) have been measured using 'Backscatter Ps' production on a Mo surface by observation of a change in the emitted Lyman- alpha intensity under resonant microwave irradiation. Production, fine structure transitions and Lyman- alpha decay of the Ps atoms took place inside a waveguide designed to transmit the microwave frequencies of 8.6, 13.0 and 18.5 GHz for the transitions from the 23S1 state to the 23PJ, J=2, 1, 0, states, respectively. In the presence of a magnetic field, all transitions observed show a shift to higher frequencies, compared with earlier calculations and measurements in zero magnetic field. The deviations exceed the expected Zeeman shift significantly but may be explained by assuming a motional Stark effect as predicted by Lewis and Hughes for Ps with kinetic energies of several eV.

We have collected all known theoretical contributions to the energy levels of positronium and present a complete listing for the states n = 1, 2 and 3. We give the explicit dependence of the energy levels on the quantum numbers n, L, S and J up to the order R∞α3. In the next higher order R∞α4 only the contributions to S- and P-states are completely known. The annihilation rates of para- and ortho-positronium are completely listed up to the orders R∞α5 and R∞α6, respectively. We compare calculated values of energy levels and annihilation rates with experimentally observed quantities.

An analysis is made of the reasons for the onset of a Penning discharge in electron-optical devices operating at moderate and high vacuum in the presence of an accompanying magnetic field. Methods of suppressing this discharge are recommended. The main results of tests to eliminate the Penning discharge in the test rig at the Joint Institute of Nuclear Research (Dubna) and in the CERN Low Energy Antiproton Ring (LEAR) (Geneva) are presented.

A23 GROUND VISCOSITY AND STIFFNESS MEASUREMENTS USING DIFFERENT VIBRATOR CONTROL SYSTEMS Abstract 1 In early December 2003 Saudi Aramco conducted an experiment measuring ground viscosity (Gv) and stiffness (Gs) using two types of vibrator control systems currently available on its seismic crews. These measured ground attributes (Gv and Gs) are used to derive near surface velocity data that can be then used to interpolate between uphole locations. The measurements were taken over 2x2km grid an area large enough to sample varying terrain conditions: unconsolidated sand and limestone outcrop. The grid spacing of the measurements was similar to the spacing used

O/sup 8+/ and O/sup 6+/ ions were stored in the CERN Low-Energy Antiproton Ring (LEAR) during a machine experiment session. The aim was to obtain some hints on the lifetime of heavy ion beams in a good cooling ring vacuum and to test cooling and stacking of ions. Stochastic cooling was used to compensate the beam decay due to multiple scattering on the residual gas, which is the most important effect on lifetime. An equilibrium momentum spread of less than 5*10/sup -4/ was measured, thus proving the efficiency of stochastic cooling for multiply charged ions. With the vacuum conditions of LEAR (2.6*10/sup -12/ torr gauge reading with a residual gas of 90% H/sub 2/), measured beam lifetimes are 25 min for O/sup 6+/ at 7.2 MeV/u and 600 min for O/sup 8+/ at 11.5 MeV/u. These numbers set favorable limits for low-energy ion storage rings. >

The LEAR electron cooler uses dense electron beams. Because of this high density the large space-charge potential induces significant drawbacks for the cooling process itself. As a consequence a space-charge neutralisation system has been implemented on the cooler. It consists of two positively polarised pairs of electrodes, placed on the outside of the drift space, which aim to store the ionised positive ions of charge Z. The major difficulty arises in the neutralisation instabilities. This paper reports on the technological aspects, the measurement techniques and the results.

This paper describes intentions to use the superconducting ELBE-LINAC, which is under construction at Forschungszentrum Rossendorf near Dresden/Germany, for the production of an intense slow positron beam of about 2.7×108 e+s−1. Possible experiments in atomic, nuclear, and solid state physics are outlined and especially main applications for materials science—being yet under debate—are mentioned.

We report on the first direct measurement of the g-factor of a highly charged ion. The experimental determination of the magnetic moment (g-factor) of the bound electron in hydrogen-like ions is an important test of the theory of Quantum Electrodynamics in strong nuclear Coulomb fields. For this purpose a single hydrogen-like ion is stored in the magnetic field of a Penning trap. The g-factor is measured by inducing spin flip transitions with a microwave field at the Larmor precession frequency of the bound electron. The magnetic field is calibrated by measuring the cyclotron frequency of the stored ion. The first results were obtained for a hydrogen-like carbon ion (C5+). The experimental precision is high enough to verify the relativistic contribution to the g-factor on the 10−3 level.

The LEAR machine is foreseen to be used as a lead ion accumulator in the injector chain for the LHC. Therefore, to test the principle of Pb54+ ion accumulation in LEAR, at 4.2 MeV/u, a number of studies and experiments have been made aimed at determining the improvements and modifications necessary to fulfill the LHC requirements. Amongst subjects studied we have investigated: a) The ion production and the injection line matching, b) The linac energy ramping in view of accumulation through combined longitudinal-transverse multi-turn injection, c) The ion beam lifetime and recombination processes, and finally d) The electron cooling time, as a function of the lattice parameters at the cooler. Recent experiments and measurements will be reported and commented in this paper. Also mentioned are some particular diagnostic methods.

This paper reviews the recent performance of the AAC and LEAR. Activities on the AAC include the successful exploitation of a magnetic horn as an antiproton collector lens and an energy-saving mode of operation, which has been possible since 1992, when LEAR became the only client of the AAC. LEAR worked in its full momentum range between 100 MeV/c and 2 GeV/c, with perform-ance (intensities, ejection modes and spill length) exceeding the design specifications. Improvements are described, which contributed to the quality of the beam delivered to experiments. The reliability and availability of the antiproton machines are also discussed.