Petawatt Laser Guiding and Electron Beam Acceleration to 8 GeV in a Laser-Heated Capillary Discharge Waveguide.

Guiding of relativistically intense laser pulses with peak power of 0.85 PW over 15 diffraction lengths was demonstrated by increasing the focusing strength of a capillary discharge waveguide using laser inverse bremsstrahlung heating. This allowed for the production of electron beams with quasimonoenergetic peaks up to 7.8 GeV, double the energy that was previously demonstrated. Charge was 5 pC at 7.8 GeV and up to 62 pC in 6 GeV peaks, and typical beam divergence was 0.2 mrad.

The impact of coronary angiography on renal transplant function.

INTRODUCTION: There may be reluctance to perform coronary angiography in kidney transplant patients due to perceived risk of iodinated contrast, despite an increased risk of cardiovascular disease compared with the general population. AIM: We sought to determine if renal transplant function was adversely affected within 7, 30 and 180 days of coronary angiography. DESIGN AND METHODS: Renal transplant recipients undergoing coronary angiography in a single centre (01/2006-02/2018) were identified retrospectively. Baseline and highest SCr within 7, 30 and 180 days of coronary angiography were extracted from the electronic patient record. Rise in creatinine >26 micromol/l was considered significant [equivalent to Acute Kidney Injury (AKI) Network criteria stage 1 AKI] and case note review performed to determine circumstance of renal decline. RESULTS: There were 127 coronary angiographies conducted in 90 patients: 67.7% were male and mean age was 58.0 (±10.1) years. There was AKI within 7 days in 18.9% cases, but SCr returned to baseline within 7 days or there was an alternative explanation for AKI in 83.3% of these. In the remaining four cases, there was progressive decline in renal transplant function. In the absence of critical illness, no patient required dialysis or extended hospital stay for contrast-associated AKI. CONCLUSIONS: In this cohort of renal transplant recipients undergoing coronary angiography, AKI occurred in a minority of cases, and in more than 95% of such cases this effect was transient, with progressive renal decline a rare and predictable event. Renal transplant should not be regarded as a contraindication to coronary angiography.

Measured Emittance Dependence on the Injection Method in Laser Plasma Accelerators.

Single-shot, charge-dependent emittance measurements of electron beams generated by a laser plasma accelerator (LPA) reveal that shock-induced density down-ramp injection produces beams with normalized emittances a factor of 2 smaller than beams produced via ionization injection. Such a comparison is made possible by the tunable LPA setup, which allows electron beams with nearly identical central energy and peak spectral charge density to be produced using the two distinct injection mechanisms. Parametric measurements of this type are essential for the development of LPA-based applications which ultimately require high charge density and low emittance.

Multistage coupling of independent laser-plasma accelerators.

Laser-plasma accelerators (LPAs) are capable of accelerating charged particles to very high energies in very compact structures. In theory, therefore, they offer advantages over conventional, large-scale particle accelerators. However, the energy gain in a single-stage LPA can be limited by laser diffraction, dephasing, electron-beam loading and laser-energy depletion. The problem of laser diffraction can be addressed by using laser-pulse guiding and preformed plasma waveguides to maintain the required laser intensity over distances of many Rayleigh lengths; dephasing can be mitigated by longitudinal tailoring of the plasma density; and beam loading can be controlled by proper shaping of the electron beam. To increase the beam energy further, it is necessary to tackle the problem of the depletion of laser energy, by sequencing the accelerator into stages, each powered by a separate laser pulse. Here, we present results from an experiment that demonstrates such staging. Two LPA stages were coupled over a short distance (as is needed to preserve the average acceleration gradient) by a plasma mirror. Stable electron beams from a first LPA were focused to a twenty-micrometre radius--by a discharge capillary-based active plasma lens--into a second LPA, such that the beams interacted with the wakefield excited by a separate laser. Staged acceleration by the wakefield of the second stage is detected via an energy gain of 100 megaelectronvolts for a subset of the electron beam. Changing the arrival time of the electron beam with respect to the second-stage laser pulse allowed us to reconstruct the temporal wakefield structure and to determine the plasma density. Our results indicate that the fundamental limitation to energy gain presented by laser depletion can be overcome by using staged acceleration, suggesting a way of reaching the electron energies required for collider applications.

Active Plasma Lensing for Relativistic Laser-Plasma-Accelerated Electron Beams.

Compact, tunable, radially symmetric focusing of electrons is critical to laser-plasma accelerator (LPA) applications. Experiments are presented demonstrating the use of a discharge-capillary active plasma lens to focus 100-MeV-level LPA beams. The lens can provide tunable field gradients in excess of 3000 T/m, enabling cm-scale focal lengths for GeV-level beam energies and allowing LPA-based electron beams and light sources to maintain their compact footprint. For a range of lens strengths, excellent agreement with simulation was obtained.

Plasma undulator based on laser excitation of wakefields in a plasma channel.

An undulator is proposed based on the plasma wakefields excited by a laser pulse in a plasma channel. Generation of the undulator fields is achieved by inducing centroid oscillations of the laser pulse in the channel. The period of such an undulator is proportional to the Rayleigh length of the laser pulse and can be submillimeter, while preserving high undulator strength. The electron trajectories in the undulator are examined, expressions for the undulator strength are presented, and the spontaneous radiation is calculated. Multimode and multicolor laser pulses are considered for greater tunability of the undulator period and strength.

Adaptation of red blood cell lysis represents a fundamental breakthrough that improves the sensitivity of Salmonella detection in blood.

AIMS: Isolation of Salmonella Typhi from blood culture is the standard diagnostic for confirming typhoid fever but it is unavailable in many developing countries. We previously described a Microwave Accelerated Metal Enhanced Fluorescence (MAMEF)-based assay to detect Salmonella in medium. Attempts to detect Salmonella in blood were unsuccessful, presumably due to the interference of erythrocytes. The objective of this study was to evaluate various blood treatment methods that could be used prior to PCR, real-time PCR or MAMEF to increase sensitivity of detection of Salmonella. METHODS AND RESULTS: We tested ammonium chloride and erythrocyte lysis buffer, water, Lymphocyte Separation Medium, BD Vacutainer(®) CPT(™) Tubes and dextran. Erythrocyte lysis buffer was the best isolation method as it is fast, inexpensive and works with either fresh or stored blood. The sensitivity of PCR- and real-time PCR detection of Salmonella in spiked blood was improved when whole blood was first lysed using erythrocyte lysis buffer prior to DNA extraction. Removal of erythrocytes and clotting factors also enabled reproducible lysis of Salmonella and fragmentation of DNA, which are necessary for MAMEF sensing. CONCLUSIONS: Use of the erythrocyte lysis procedure prior to DNA extraction has enabled improved sensitivity of Salmonella detection by PCR and real-time PCR and has allowed lysis and fragmentation of Salmonella using microwave radiation (for future detection by MAMEF). SIGNIFICANCE AND IMPACT OF THE STUDY: Adaptation of the blood lysis method represents a fundamental breakthrough that improves the sensitivity of DNA-based detection of Salmonella in blood.

Acute tubulointerstitial nephritis in Scotland.

BACKGROUND AND AIMS: Acute tubulointerstitial nephritis (ATIN) is a potentially reversible cause of acute kidney injury with the majority of cases drug related. Our aims were to examine the incidence profile of patients with ATIN in Scotland and to assess the impact of corticosteroid treatment. DESIGN AND METHODS: All adult patients with biopsy-proven ATIN, diagnosed between 2000 and 2012, presenting to renal units serving 1.9 of Scotland's 5 million population were included. Patient demographics, presenting, aetiologic and pathologic features, treatment given and outcome were extracted from patient records. RESULTS: In total, 171 cases representing 4.7% of native renal biopsies were identified. Median serum creatinine (sCr) was 327 µmol/l at biopsy (106 µmol/l at baseline). Eosinophilia, fever or rash was present in 57% with all 3 in only 1.1%. Active urinary sediment was found in 68%. Aetiology appeared drug induced in 73%. Proton pump inhibitors (PPIs) were likely causative in almost as many cases as antibiotics (35% each) and were more frequently implicated than non-steroidal anti-inflammatory drugs (20%). Number of PPI-related cases paralleled the rising prescription of these drugs. Corticosteroids were prescribed in 59% of drug-induced ATIN (median sCr at biopsy: 356 µmol/l vs. 280 µmol/l in those managed conservatively). There was no difference in sCr at 1, 6 and 12 months, with similar proportions of both groups experiencing complete renal recovery (48% vs. 41%) and becoming dialysis dependent (10% in both). CONCLUSIONS: Incidence of biopsy-proven ATIN in Scotland has been rising over the past decade with the majority of cases drug induced. Evidence supporting corticosteroid treatment is lacking.

Measured bremsstrahlung photonuclear production of 99Mo ((99m)Tc) with 34 MeV to 1.7 GeV electrons.

(99)Mo photonuclear yield was measured using high-energy electrons from Laser Plasma Accelerators and natural molybdenum. Spectroscopically resolved electron beams allow comparisons to Monte Carlo calculations using known (100)Mo(γ,n)(99)Mo cross sections. Yields are consistent with published low-energy data, and higher energy data are well predicted from the calculations. The measured yield is (15±2)×10(-5) atoms/electron (0.92±0.11 GBq/µA) for 25 mm targets at 33.7 MeV, rising to (1391±20)×10(-5) atoms/electron (87±2 GBq/µA) for 54 mm/ 1.7 GeV, with peak power-normalized yield at 150 MeV.

Multi-GeV electron beams from capillary-discharge-guided subpetawatt laser pulses in the self-trapping regime.

Multi-GeV electron beams with energy up to 4.2 GeV, 6% rms energy spread, 6 pC charge, and 0.3 mrad rms divergence have been produced from a 9-cm-long capillary discharge waveguide with a plasma density of ≈7×10¹7 cm⁻³, powered by laser pulses with peak power up to 0.3 PW. Preformed plasma waveguides allow the use of lower laser power compared to unguided plasma structures to achieve the same electron beam energy. A detailed comparison between experiment and simulation indicates the sensitivity in this regime of the guiding and acceleration in the plasma structure to input intensity, density, and near-field laser mode profile.

Taurolidine-citrate-heparin catheter lock solution reduces staphylococcal bacteraemia rates in haemodialysis patients.

BACKGROUND: Infection is second only to cardiovascular disease as a cause of death in the haemodialysis (HD) population. AIM: : To assess the effect of introducing catheter lock solution taurolidine-citrate-heparin to all tunnelled central venous catheters (TCVCs) on staphylococcal bloodstream infection rates in patients on chronic HD. DESIGN: Observational, prospective analysis of the incidence rates of staphylococcal bacteraemic events in National Health Service (NHS) Greater Glasgow & Clyde and NHS Forth Valley between April 2011 and June 2013, with taurolidine-citrate-heparin catheter lock solution introduced July 2012. METHODS: Data were collected each calendar quarter through a structured query language interrogation of the renal unit electronic patient record, with staphylococcal bacteraemic events expressed per 1000 vascular access exposed days. Comparison between pre- and post-intervention periods was made by student's t-testing. RESULTS: Two hundred and thirty-nine staphylococcal bacteraemic events occurred over a total of 424,835 HD days in 565 patients; 81 events in 289,389 arterio-venous fistula or graft (AVF/AVG) HD days and 158 events in 135 446 TCVC HD days. Following the introduction of taurolidine-citrate-heparin, bacteraemic events in patients dialysing via a TCVC fell from 1.59/1000 HD days to 0.69/1000 HD days, P = 0.004. The staphylococcal bacteraemia rate in AVF/AVGs remained unchanged; 0.30 vs. 0.26/1000 HD days, P = 0.52. CONCLUSIONS: Replacing heparin 5000 IU with Taurolidine-citrate-heparin as catheter lock solution was associated with a statistically significant 56% reduction in staphylococcal bloodstream infection rates in our TCVC HD population.

Two-color laser-ionization injection.

A method is proposed to generate femtosecond, ultralow emittance (∼10-8 m rad), electron beams in a laser-plasma accelerator using two lasers of different colors. A long-wavelength pump pulse, with a large ponderomotive force and small peak electric field, excites a wake without fully ionizing a high-Z gas. A short-wavelength injection pulse, with a small ponderomotive force and large peak electric field, copropagating and delayed with respect to the pump laser, ionizes a fraction of the remaining bound electrons at a trapping wake phase, generating an electron beam that is accelerated in the wake.

Seed train development for the fermentation of bagasse from sweet sorghum and sugarcane using a simplified fermentation process.

A process was developed for seed culture expansion (3.6 million-fold) using 5% of the hemicellulose hydrolysate from dilute acid pretreatment as the sole organic nutrient and source of sugar. Hydrolysate used for seed growth was neutralized with ammonia and combined with 1.0mM sodium metabisulfite immediately before inoculation. This seed protocol was tested with phosphoric acid pretreated sugarcane and sweet sorghum bagasse using a simplified process with co-fermentation of fiber, pentoses, and hexoses in a single vessel (SScF). A 6h liquefaction (L) step improved mixing prior to inoculation. Fermentations (L+SScF process) were completed in 72 h with high yields (>80 gal/US ton). Ethanol titers for this L+SScF process ranged from 24 g/L to 32 g/L, and were limited by the bagasse concentration (10% dry matter).

Acute kidney injury: outcomes and quality of care.

BACKGROUND: Deficiencies in management have been highlighted as contributory factors in the death of many patients with acute kidney injury (AKI). However, there is little evidence addressing the quality of care provided to patients with milder AKI. AIM: The aim of this study is to evaluate the quality of care provided to a non-select cohort of patients with AKI and evaluate discrepancies in causation, recognition and management. DESIGN: Retrospective inception cohort study. METHODS: Demographic data were collected for all 1577 patients admitted to a University Teaching Hospital during a 1-month period. Baseline, admission and peak creatinine were correlated with mortality and length of hospital admission. AKI was classified according to Kidney Disease Improving Global Outcomes criteria. A retrospective case note review of all patients with AKI was carried out to evaluate quality of documentation and clinical management of AKI. Multivariate analysis was undertaken to determine risk factors for AKI. RESULTS: Incidence of AKI on admission was 4.6%. A further 10.3% developed AKI while in hospital. All cause mortality was 4-fold higher among patients with AKI compared with those without (19 vs. 3.8%; P < 0.001). Mortality was significantly higher in those patients who developed AKI while an in-patient compared with those with AKI on admission (27.3 vs. 11.8%; P < 0.001). Diabetes, clinician perception of frailty, age and treatment with angiotensin-converting enzyme inhibitor prior to admission were found to be independent risk factors for AKI. AKI was unrecognized in 23.5% of patients, two-thirds of whom were discharged without resolution of renal function. Significant weaknesses in management were poorly kept fluid balance charts (48.2%), failure to withhold nephrotoxic drugs (38.8%) and failure to act upon abnormal biochemistry (41%) in a timely fashion. CONCLUSION: AKI is common in hospitalized patients and associated with a significant increase in hospital stay and mortality. AKI is often found in conjunction with other organ failure and in many cases is not preventable. Nevertheless clinicians need to be more vigilant of small creatinine rises to permit early intervention particularly among elderly and frail patients.

Skin tumours in the West of Scotland renal transplant population.

BACKGROUND: Organ transplant recipients have an increased risk of skin cancers. A specialist dermatology clinic for renal transplant recipients (RTRs) was established in 2005. OBJECTIVES: To analyse the type and incidence of skin cancers in prevalent patients in the West of Scotland after renal transplant, and to analyse the impact of the time since transplant and the immunosuppression regimen. METHODS: Skin cancer data for RTRs attending the transplant dermatology clinic over a 38-month period were collected and recorded in the West of Scotland electronic renal patient record. Skin cancer data were intrinsically linked to each individual's transplant and immunosuppression data. RESULTS: Overall, 610 patients attended. The median follow-up time from the date of first transplant was 10 years. Ninety-three patients (15.2%) had experienced a total of 368 skin cancers since transplant, and the prevalence increased with time since transplant. Basal cell carcinomas (BCCs) occurred in 74 patients (12.1%) and squamous cell carcinomas (SCCs) in 42 patients (6.9%). Three patients (0.5%) had experienced a melanoma. The SCC:BCC ratio was 0.7. Survival analysis showed significant reduction in the time to develop skin cancer in patients transplanted from 1995 onwards (P < 0.0001) and in patients who had been on triple immunosuppressant therapy at 1 year after transplant, compared with dual therapy (P < 0.0001). CONCLUSIONS: This is the first study of skin cancer in prevalent Scottish RTRs. The incidence of skin cancer is high and appears to have a direct relationship to the overall burden of immunosuppression. The SCC:BCC ratio, which is lower than reports from other centres, deserves further scrutiny.

Below-target postoperative arterial blood pressure but not central venous pressure is associated with delayed graft function.

Delayed graft function (DGF) is a major issue in kidney transplantation and is associated with reduced graft and patient survival. The condition results from the summative effects of multiple injurious processes associated with transplantation with many underlying factors being nonmodifiable. Reducing cold ischemic time and machine perfusion have decreased the DGF incidence but peri-/postoperative injury resulting from suboptimal perfusion may also be critical to the development of DGF. We investigated the effect of perfusion parameters and other key variables on the incidence of DGF in 149 consecutive renal transplants. The occurrence of any recorded subtarget (70 mm Hg) mean arterial pressure (MAP) was significantly associated with DGF (perioperative P = .005; postoperative P = .002) while the occurrence of a subtarget (8 cm H(2)O) central venous pressure (CVP) among other variables was not. Routine continuous blood pressure monitoring is rare postoperatively and is shown to be more accurate than CVP in assessing renal perfusion and guiding management in the postoperative period.

Low-emittance electron bunches from a laser-plasma accelerator measured using single-shot x-ray spectroscopy.

X-ray spectroscopy is used to obtain single-shot information on electron beam emittance in a low-energy-spread 0.5 GeV-class laser-plasma accelerator. Measurements of betatron radiation from 2 to 20 keV used a CCD and single-photon counting techniques. By matching x-ray spectra to betatron radiation models, the electron bunch radius inside the plasma is estimated to be ~0.1 µm. Combining this with simultaneous electron spectra, normalized transverse emittance is estimated to be as low as 0.1 mm mrad, consistent with three-dimensional particle-in-cell simulations. Correlations of the bunch radius with electron beam parameters are presented.

SYBR Green I: fluorescence properties and interaction with DNA.

In this study, we have investigated the fluorescence properties of SYBR Green I (SG) dye and its interaction with double-stranded DNA (dsDNA). SG/dsDNA complexes were studied using various spectroscopic techniques, including fluorescence resonance energy transfer and time-resolved fluorescence techniques. It is shown that SG quenching in the free state has an intrinsic intramolecular origin; thus, the observed >1,000-fold SG fluorescence enhancement in complex with DNA can be explained by a dampening of its intra-molecular motions. Analysis of the obtained SG/DNA binding isotherms in solutions of different ionic strength and of SG/DNA association in the presence of a DNA minor groove binder, Hoechst 33258, revealed multiple modes of interaction of SG inner groups with DNA. In addition to interaction within the DNA minor groove, both intercalation between base pairs and stabilization of the electrostatic SG/DNA complex contributed to increased SG affinity to double-stranded DNA. We show that both fluorescence and the excited state lifetime of SG dramatically increase in viscous solvents, demonstrating an approximate 200-fold enhancement in 100 % glycerol, compared to water, which also makes SG a prospective fluorescent viscosity probe. A proposed structural model of the SG/DNA complex is compared and discussed with results recently reported for the closely related PicoGreen chromophore.