Cherenkov radiation-based optical fibre diagnostics of fast electrons generated in intense laser-plasma interactions

Diagnosing fast electrons is important to understand the physics underpinning intense laser-produced plasmas. Here, we demonstrate experimentally that a Cherenkov radiation-based optical fibre can serve as a reliable diagnostic to characterize the fast electrons escaping from solid targets irradiated by ultra-intense laser pulses. Using optical fibre loops, the number and angular distributions of the escaping electrons are obtained. The data agree well with measurements made using image plate stacks. The optical fibre can be operated at high-repetition rates and is insensitive to x-rays and ion beams, which makes it advantageous over other routinely used fast electron diagnostics in some aspects.

Blood Metal Ion Levels Have Limited Utility in the Surveillance of Asymptomatic Large-Head Metal-on-Metal Total Hip Arthroplasties

BACKGROUND

Blood cobalt (Co) and chromium (Cr) ion levels have been used as surveillance tools for adverse reaction to metal debris (ARMD) in metal-on-metal (MoM) articulations with varying thresholds in different countries. The aim of our study is to present the serial 12-year blood Co and Cr levels in a cohort of MoM total hip arthroplasties (THAs) with femoral head size ≥36 mm and analyze their utility in asymptomatic patients at current thresholds.

METHODS

A total of 256 patients with unilateral MoM THA with femoral head size ≥36 mm were included in this study with data collected prospectively. The implants used were Birmingham hip resurfacing cup-Freeman stem (BHR-F) or an Articular Surface Resurfacing cup-Corail/S-ROM stem. Annual follow-up with blood Co and Cr measurements was done as per Medicines and Healthcare Products Regulatory Agency (MHRA) of the United Kingdom guidelines. Receiver operating characteristic curve was plotted based on the sensitivity and specificity of blood metal ion values to detect ARMD. The metal ion levels in asymptomatic patients were analyzed separately.

RESULTS

Receiver operating characteristic curves showed poor discriminatory ability for both Co and Cr values in predicting ARMD at 7 μg/L. The sensitivity of Co and Cr was 82.1% and 53.5%, respectively, and their positive predictive values were 43.8% and 67.6%, respectively. After 7 years, there was no significant change in Co values, and there was a decline in Cr value after 9 years in asymptomatic patients.

CONCLUSION

To the best of our knowledge, this is the first study to describe the behavior of serial blood metal ion levels in asymptomatic large-diameter MoM THA. We suggest that annual blood Co and Cr have limited discriminant capacity in diagnosing the occurrence of metallosis and their measurement beyond 7 years is of limited utility in asymptomatic patients.

A mixed-methods study of the causes and impact of poor teamwork between junior doctors and nurses

OBJECTIVES

This study aimed to collect and analyse examples of poor teamwork between junior doctors and nurses; identify the teamwork failures contributing to poor team function; and ascertain if particular teamwork failures are associated with higher levels of risk to patients.

DESIGN

Critical Incident Technique interviews were carried out with junior doctors and nurses.

SETTING

Two teaching hospitals in the Republic of Ireland.

PARTICIPANTS

Junior doctors (n = 28) and nurses (n = 8) provided descriptions of scenarios of poor teamwork. The interviews were coded against a theoretical framework of healthcare team function by three psychologists and were also rated for risk to patients by four doctors and three nurses.

RESULTS

A total of 33 of the scenarios met the inclusion criteria for analysis. A total of 63.6% (21/33) of the scenarios were attributed to 'poor quality of collaboration', 42.4% (14/33) to 'poor leadership' and 48.5% (16/33) to a 'lack of coordination'. A total of 16 scenarios were classified as high risk and 17 scenarios were classified as medium risk. Significantly more of the high-risk scenarios were associated with a 'lack of a shared mental model' (62.5%, 10/16) and 'poor communication' (50.0%, 8/16) than the medium-risk scenarios (17.6%, 3/17 and 11.8%, 2/17, respectively).

CONCLUSION

Poor teamwork between junior doctors and nurses is common and places patients at considerable risk. Addressing this problem requires a well-designed complex intervention to develop the team skills of doctors and nurses and foster a clinical environment in which teamwork is supported.

Pathway to the piezoelectronic transduction logic device

The piezoelectronic transistor (PET) has been proposed as a transduction device not subject to the voltage limits of field-effect transistors. The PET transduces voltage to stress, activating a facile insulator-metal transition, thereby achieving multigigahertz switching speeds, as predicted by modeling, at lower power than the comparable generation field effect transistor (FET). Here, the fabrication and measurement of the first physical PET devices are reported, showing both on/off switching and cycling. The results demonstrate the realization of a stress-based transduction principle, representing the early steps on a developmental pathway to PET technology with potential to contribute to the IT industry.

Major ABO incompatible BMT in children: determining what residual volume of donor red cells can safely be infused following red cell depletion

Major ABO incompatible BM transplantation carries a risk of acute haemolysis. Red cell depletion reduces this risk but not all incompatible RBC (iRBCs) are removed and in children the residual volume can be significant relative to body weight. We sought to determine the volume of iRBCs that can be safely given to children. All patients receiving fresh BM from a donor with a major ABO blood group mismatch between January 2000 and July 2013 at the Hospital for Sick Children, Toronto, were included. Seventy-eight patients were identified. The median volume of iRBCs transfused was 1.6 mL/kg (range 0.1-10.6 mL/kg). Thirty-five patients had minor haemolytic events and five patients had clinically significant adverse events. Two patients, who received 3.66 and 3.9 mL iRBCs/kg, developed renal impairment and in one case hypoxia and hyperbilirubinaemia. One patient had mild hypotension that resolved with i.v. fluid. Two patients developed hypotension secondary to sepsis and unrelated to BM infusion. Although signs of haemolysis occur, with appropriate hydration and monitoring of renal function, clinically significant adverse events related to the infusion of ABO incompatible BM are rare, and, in this study, were only seen in patients receiving >3 mL/kg of iRBCs per kg.

Separated response function ratios in exclusive, forward π(±) electroproduction

The study of exclusive π(±) electroproduction on the nucleon, including separation of the various structure functions, is of interest for a number of reasons. The ratio RL=σL(π-)/σL(π+) is sensitive to isoscalar contamination to the dominant isovector pion exchange amplitude, which is the basis for the determination of the charged pion form factor from electroproduction data. A change in the value of RT=σT(π-)/σT(π+) from unity at small -t, to 1/4 at large -t, would suggest a transition from coupling to a (virtual) pion to coupling to individual quarks. Furthermore, the mentioned ratios may show an earlier approach to perturbative QCD than the individual cross sections. We have performed the first complete separation of the four unpolarized electromagnetic structure functions above the dominant resonances in forward, exclusive π(±) electroproduction on the deuteron at central Q(2) values of 0.6, 1.0, 1.6  GeV(2) at W=1.95  GeV, and Q(2)=2.45  GeV(2) at W=2.22  GeV. Here, we present the L and T cross sections, with emphasis on RL and RT, and compare them with theoretical calculations. Results for the separated ratio RL indicate dominance of the pion-pole diagram at low -t, while results for RT are consistent with a transition between pion knockout and quark knockout mechanisms.

Giant piezoresistive on/off ratios in rare-earth chalcogenide thin films enabling nanomechanical switching

Sophisticated microelectromechanical systems for device and sensor applications have flourished in the past decade. These devices exploit piezoelectric, capacitive, and piezoresistive effects, and coupling between them. However, high-performance piezoresistivity (as defined by on/off ratio) has primarily been observed in macroscopic single crystals. In this Letter, we show for the first time that rare-earth monochalcogenides in thin film form can modulate a current by more than 1000 times due to a pressure-induced insulator to metal transition. Furthermore, films as thin as 8 nm show a piezoresistive response. The combination of high performance and scalability make these promising candidates for nanoscale applications, such as the recently proposed piezoelectronic transistor (PET). The PET would mechanically couple a piezoelectric thin film with a piezoresistive switching layer, potentially scaling to higher speeds and lower powers than today's complementary metal-oxide-semiconductor technology.

Staged interventional and surgical management for complex low birthweight tetralogy of Fallot: another imperfect but legitimate strategy

Management of spelling low weight infants with complex tetralogy of Fallot is often fraught. We present a 2.8-kg infant with DiGeorge syndrome and spelling tetralogy with non-confluent pulmonary arteries, the left pulmonary artery being supplied by an aberrant ductus arteriosus from the left common carotid artery. We performed stenting of the outflow tract and the ductus to allow this patient to achieve a successful elective surgical correction.

Differential distribution of cobalt, chromium, and nickel between whole blood, plasma and urine in patients after metal-on-metal (MoM) hip arthroplasty

Evidence shows that raised cobalt (Co), chromium (Cr), and nickel (Ni) whole blood concentrations correlate with poor device outcome in patients following metal-on-metal (MoM) hip arthroplasty. To understand the local and systemic pathological effects of these raised metal concentrations it is important to define their distribution between whole blood, plasma, and urine. The metals were measured by Inductively Coupled Plasma Mass Spectrometry (ICPMS). Two hundred and five plasma, 199 whole blood, and 24 sets of urine samples were analyzed from 202 patients with Co-Cr alloy MoM hip prostheses implanted between 8 months to 12 years (mean 6.0 years) prior to analysis. Plasma Co (median 39.1 nmol/L) showed significantly positive 1:1 correlation with whole blood Co (median 45.9 nmol/L; R(2)  = 0.98, p < 0.001, slope = 1.0). Plasma Cr (median 53.8 nmol/L) and whole blood Cr (median 40.3 nmol/L) were also correlated; however, concentrations were significantly higher in plasma indicating relatively little blood cell uptake (R(2)  = 0.96, p < 0.001, slope = 1.6). Urinary Co was up to threefold higher than Cr (median 334.0 vs. 97.3 nmol/L respectively). Nickel concentrations in whole blood, plasma, and urine were low relative to Co and Cr. The analysis shows fundamental differences in the physiological handling of these metals: Co is distributed approximately equally between blood cells and plasma, whereas Cr is mainly in plasma, despite which, Cr had far less renal excretion than Co.

Remote Internet access to advanced analytical facilities: a new approach with Web-based services

Over the past decade, the increasing availability of the World Wide Web has held out the possibility that the efficiency of scientific measurements could be enhanced in cases where experiments were being conducted at distant facilities. Examples of early successes have included X-ray diffraction (XRD) experimental measurements of protein crystal structures at synchrotrons and access to scanning electron microscopy (SEM) and NMR facilities by users from institutions that do not possess such advanced capabilities. Experimental control, visual contact, and receipt of results has used some form of X forwarding and/or VNC (virtual network computing) software that transfers the screen image of a server at the experimental site to that of the users' home site. A more recent development is a web services platform called Science Studio that provides teams of scientists with secure links to experiments at one or more advanced research facilities. The software provides a widely distributed team with a set of controls and screens to operate, observe, and record essential parts of the experiment. As well, Science Studio provides high speed network access to computing resources to process the large data sets that are often involved in complex experiments. The simple web browser and the rapid transfer of experimental data to a processing site allow efficient use of the facility and assist decision making during the acquisition of the experimental results. The software provides users with a comprehensive overview and record of all parts of the experimental process. A prototype network is described involving X-ray beamlines at two different synchrotrons and an SEM facility. An online parallel processing facility has been developed that analyzes the data in near-real time using stream processing. Science Studio and can be expanded to include many other analytical applications, providing teams of users with rapid access to processed results along with the means for detailed discussion of their significance.

Metal ion levels decrease after revision for metallosis arising from large-diameter metal-on-metal hip arthroplasty

Concerns have been renewed regarding the possible long-term effects of elevated circulating levels of cobalt and chromium as a direct result of implantation of large femoral head diameter metal-on-metal bearings. In order to establish whether metal ion levels remain persistently elevated, we compared metal ion levels before and after revision surgery in patients with large head diameter (greater than 38 mm) metal-on-metal total hip arthroplasty or hip resurfacing arthroplasty. At greater than one year post removal of a large-diameter metal-on-metal hip implant for the indication of symptomatic metallosis, metal ion levels were found to fall to almost normal levels.

A high throughput in vitro mrp2 assay to predict in vivo biliary excretion

Prediction of biliary excretion is a challenge for drug discovery scientists due to the lack of in vitro assays. This study explores the possibility of establishing a simple assay to predict in vivo biliary excretion via the mrp2 transport system. In vitro mrp2 activity was determined by measuring the ATP-dependent uptake of 5(6)-carboxy-2',7'-dichlorofluorescein (CDCF) in canalicular plasma membrane vesicles (cLPM) from rat livers. The CDCF uptake was time- and concentration-dependent (K(m) of 2.2 ± 0.3 µM and V(max) of 115 ± 26 pmol/mg/min) and strongly inhibited by the mrp2 inhibitors, benzbromarone, MK-571, and cyclosporine A, with IC(50) values ≤ 1.1 µM. Low inhibition of CDCF uptake by taurocholate (BSEP inhibitor; 57 µM) and digoxin (P-gp inhibitor; 101 µM) demonstrated assay specificity towards mrp2. A highly significant correlation (r(2) = 0.959) between the in vitro IC(50) values from the described mrp2 assay and in vivo biliary excretion in rats was observed using 10 literature compounds. This study demonstrated, for the first time, that a high throughput assay could be established with the capability of predicting biliary excretion in the rat using CDCF as a substrate.